Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
  • F04C18/00—Rotary-piston pumps specially adapted for elastic fluids
  • F04C18/02—Rotary-piston pumps specially adapted for elastic fluids of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents
  • F04C18/0207—Rotary-piston pumps specially adapted for elastic fluids of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents both members having co-operating elements in spiral form
  • F04C18/0215—Rotary-piston pumps specially adapted for elastic fluids of arcuate-engagement type, i.e. with circular translatory movement of co-operating members, each member having the same number of teeth or tooth-equivalents both members having co-operating elements in spiral form where only one member is moving
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01C—ROTARY-PISTON OR OSCILLATING-PISTON MACHINES OR ENGINES
  • F01C19/00—Sealing arrangements in rotary-piston machines or engines
  • F01C19/005—Structure and composition of sealing elements such as sealing strips, sealing rings and the like; Coating of these elements
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
  • F04C25/00—Adaptations of pumps for special use of pumps for elastic fluids
  • F04C25/02—Adaptations of pumps for special use of pumps for elastic fluids for producing high vacuum
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
  • F04C27/00—Sealing arrangements in rotary-piston pumps specially adapted for elastic fluids
  • F04C27/005—Axial sealings for working fluid
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
  • F04C29/00—Component parts, details or accessories of pumps or pumping installations, not provided for in groups F04C18/00 - F04C28/00
  • F04C29/0021—Systems for the equilibration of forces acting on the pump
  • F04C29/0028—Internal leakage control
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
  • F04C2230/00—Manufacture
  • F04C2230/60—Assembly methods
  • F04C2230/602—Gap; Clearance
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
  • F04C2240/00—Components
  • F04C2240/50—Bearings
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
  • F04C2240/00—Components
  • F04C2240/80—Other components
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
  • F04C2240/00—Components
  • F04C2240/80—Other components
  • F04C2240/81—Sensor, e.g. electronic sensor for control or monitoring
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
  • F04C2240/00—Components
  • F04C2240/80—Other components
  • F04C2240/811—Actuator for control, e.g. pneumatic, hydraulic, electric

Definitions

• the present disclosure relates to the improvement of scroll vacuum pumps and methods for operating scroll vacuum pumps.
• the scroll vacuum pumps each comprise a pumping system comprising a fixed spiral component and a movable spiral component cooperating with the latter for pumping purposes, and a drive shaft rotating about a rotational axis during operation and having an eccentric section for driving the movable spiral component.
• Scroll vacuum pumps are generally known, e.g. from EP 3 153 708 A2 , EP 3 617 511 A2 , EP 3 647 599 A2 , EP 4 174 285 A1 , EP 4 253 720 A2 and EP 4 407 183 A1 .
• a scroll pump is a positive displacement pump that compresses against atmospheric pressure and can be used, among other things, as a compressor.
• a scroll vacuum pump can be used to create a vacuum in a chamber connected to a gas inlet of the scroll vacuum pump.
• Scroll vacuum pumps are also known as spiral vacuum pumps or spiral conveying devices.
• the pumping principle underlying a scroll vacuum pump is generally known from the state of the art and will therefore only be briefly explained below.
• the pumping system of a scroll vacuum pump comprises two nested or interlocked, for example Archimedean, spiral cylinders, which are also referred to simply as spirals.
• Each spiral cylinder comprises at least one spiral wall with a A support, in particular a plate-shaped support, provided on a spiral wall, wherein the outer turns of the spiral cylinder, for example the two or three outermost turns of the spiral cylinder, can be formed by wall sections that are each at a constant distance from the center of the spirals in the circumferential direction. Even if these wall sections do not strictly speaking form spiral sections but circular sections, in the context of the present disclosure they are attributed to the spiral and referred to as turns of the spiral.
• the spiral cylinders are nested in such a way that the two spiral cylinders enclose crescent- or sickle-shaped volumes (discharge chambers) in sections.
• One of the two spirals is immobile or fixed in the pump housing, whereas the other spiral, together with its support, can be moved along a circular path via the eccentric section of the drive shaft, which is why this spiral, together with its support, is also referred to as an orbiter.
• This movable spiral component thus performs a so-called centrally symmetric oscillation, which is also referred to as "orbiting" or "wobbling.”
• a crescent-shaped volume (discharge chamber) enclosed between the spiral cylinders migrates increasingly inward within the spirals as the movable spiral component orbits.
• This moving volume conveys the process gas to be pumped from a radially outer gas inlet of the pump system radially inward to a gas outlet of the pump system, located primarily in the center of the spiral.
• the eccentric drive i.e. the drive shaft with the eccentric section
• the eccentric drive is located inside the housing of the scroll vacuum pump on the side of the carrier facing away from the spiral of the orbiter and is in practice usually surrounded by a deformable sleeve, for example a bellows, which on the one hand serves to seal the drive against the intake area and on the other hand as It serves as an anti-rotation device for the orbiter, as it could otherwise rotate around itself without a rotation device.
• the deformable sleeve can, for example, be connected to the support at a first end, while the second end of the deformable sleeve, opposite the first end, can be screwed to a housing base inside the housing using several fastening elements.
• the deformable sleeve e.g., corrugated bellows
• the deformable sleeve is permanently sealed and thus sealed against a pump housing and the movable scroll component.
• the assembly comprising the orbiter and the deformable sleeve (e.g., bellows) can be pre-assembled during pump assembly, allowing this assembly to be inserted into the pump housing as a single unit.
• the second end of the deformable sleeve can then be screwed to the housing base using the fasteners.
• the spiral walls of the movable scroll component and the spiral walls of the stationary scroll component are each provided with a separate sealing element on their end faces facing away from the support, which is also known as a tip seal in the field of scroll vacuum pumps.
• the tip seals which are typically made of plastic, seal the aforementioned volumes enclosed by the spiral walls and are therefore of particular importance for the vacuum performance of a scroll vacuum pump.
• tip seals also have disadvantages. Tip seals have a limited service life and must be replaced regularly, increasing the maintenance effort for scroll vacuum pumps. Tip seals also generate abrasion. Furthermore, tip seals are sensitive to certain external influences, such as radioactive radiation, to which scroll vacuum pumps can be exposed in certain applications.
• Scroll vacuum pumps without tip seals on the scroll walls are known, but they require extremely precise relative positioning between the stationary scroll component and the movable scroll component in order to achieve a precisely defined axial gap—relative to the rotational axis—between the end faces of the scroll walls of one scroll component and the so-called groove base or scroll base (hereinafter referred to simply as the scroll base), i.e., the facing side of the carrier of the other scroll component.
• the scroll base i.e., the facing side of the carrier of the other scroll component.
• the two axial gap dimensions can be the same or different, i.e. the axial gap dimension between the spiral wall end faces of the orbiter and the groove base of the spiral casing on the one hand and the axial gap dimension between the spiral wall end faces of the spiral casing and the groove base of the orbiter on the other hand can either be the same or different from each other.
• the axial gap dimension is understood in the context of the present disclosure to be the gap dimension between the end face of a respective spiral wall of one spiral component and the groove base of the other spiral component, even if the spiral wall is provided with a sealing element (TipSeal), ie in this case the axial gap dimension does not mean the gap dimension with respect to the end face of the sealing element, but also understood with respect to the front side of the spiral wall provided with the sealing element.
• Scroll vacuum pumps without TipSeals could therefore also be used in applications of practical interest where the focus is less on particularly high vacuum performance and more on maintaining a vacuum performance that is as constant as possible over time.
• the fixed scroll component is also called the spiral casing and the movable scroll component is also called the orbiter.
• the "adjustment" of the axial gap can also serve the purpose of adjusting or compensating for misalignments of one of the two spiral components relative to the pump casing and/or misalignments of the two spiral components relative to each other.
• a respectively adjusted or to be adjusted Axial gap dimension also means an adjusted or adjustable misalignment.
• Adjusting the axial gap also includes “maintaining" the axial gap at a setpoint, which can be specified by the scroll vacuum pump manufacturer for a specific application, or which can be specified by the scroll vacuum pump user, i.e., can be individually selected. Such "maintaining" of the axial gap may involve changing the axial gap if deviations from a setpoint occur during pump operation, for example, due to thermal influences or other reasons, and a change is therefore necessary.
• the “adjustment" of the axial gap also includes measures that enable one or both of the scroll components to self-adjust—and thus the relative position between the two scroll components—for example, in the sense of "alignment,” particularly after a run-in period of the scroll vacuum pump.
• running-in is mentioned in the context of this disclosure, e.g., in the sense of grinding, this refers to the running-in of sealing elements (tip seals) present on the end faces of the scroll walls, even if the presence of sealing elements is not explicitly mentioned in the respective context.
• adjusting agent is to be understood broadly and can also include a "passive” measure, for example a specific material pairing, a special thermal expansion coefficient or a special thermal emissivity on a component or on a section of a component of the scroll vacuum pump or a combination of different thermal expansion coefficients or special thermal emissivities.
• An “active" actuating means can, for example, comprise an arrangement comprising at least one component or assembly and an associated controller. By appropriately controlling the component or assembly, a desired actuating effect can be achieved.
• the adjusting means can be configured to adjust the axial gap dimension outside of pumping operation.
• the axial gap dimension can, for example, be adjusted once during assembly of the scroll vacuum pump. This is also referred to as initial axial gap adjustment.
• the adjusting means can be configured so that the axial gap dimension can be adjusted in specific situations, for example, during maintenance of the scroll vacuum pump or when preparing for a new application.
• the axial gap dimension can, for example, be adjusted manually.
• the adjusting means is designed to adjust the axial gap dimension during pumping operation.
• the setting can be done manually, for example.
• the adjustment can be carried out within the framework of a closed-loop control system.
• the axial gap dimension is the controlled variable, the value of which is continuously measured as the actual value and compared with a setpoint value, which may be dependent on one or more parameters.
• the manipulated variable for influencing the axial gap dimension can be different.
• the speed of a fan can serve as a control variable to influence heat transfer within the pump so that more or less heat reaches a specific component or a section of a component whose thermal expansion is to be influenced by the fan, in order to apply appropriate mechanical stress to the movable spiral component and thus adjust the axial gap accordingly.
• control example explained above is intended to illustrate only how the axial gap dimension can be adjusted within the framework of a control during pump operation.
• Manual adjustment can also be performed during pump operation.
• Manual includes operating or adjusting any type of actuator, both manually and with a tool.
• the actuating means can be designed to actuate one of the two spiral components, in particular the movable spiral component, or both spiral components.
• the actuation is effected mechanically, in particular.
• the mechanical actuation can be direct or indirect, whereby indirect mechanical actuation is understood to mean that the spiral component in question is acted upon via another component.
• the application of force is an active measure for adjusting the axial gap.
• a passive measure such as the selection of materials with different thermal expansion coefficients.
• a load to one of the two spiral components can take advantage of the fact that the bearing of the movable spiral component on the eccentric section of the drive shaft allows a certain slight axial mobility.
• the movable spiral component can be supported, for example, by a rolling bearing.
• a so-called flange bearing is used to support the movable spiral component on the eccentric section of the drive shaft.
• the bearing can be provided by separate ball bearings.
• the actuating means is designed to act on the spiral component or both spiral components at one point, in particular lying on the axis of rotation, and/or at several points, in particular distributed around the axis of rotation.
• the adjusting means can be designed to influence the axial relative position between the two spiral components with respect to the axis of rotation.
• the adjusting means can be designed to move one of the two spiral components, in particular the movable spiral component, or both spiral components in the axial direction or to tilt them with respect to the axis of rotation.
• a measuring device may be provided that is configured to measure the axial gap dimension at one or more locations.
• the axial gap dimension can be measured continuously during pump operation.
• the axial clearance can be measured directly by determining the size of the respective axial gap between an end face of a scroll wall of one scroll component and the base, i.e., the scroll root, of the other scroll component.
• the axial clearance can be measured indirectly by determining a value of another quantity that can serve as the axial clearance, e.g., a value for the axial distance between a pump casing and a section, e.g., the base, i.e., the scroll root, of the movable scroll component or the back of the movable scroll component support.
• Measuring the axial gap dimension does not only involve determining a single value; rather, multiple values can be determined at different locations, allowing a misalignment of one or both of the spiral components to be identified as such or even quantified.
• measuring the axial gap dimension also involves measuring a misalignment of one or both spiral components.
• a misalignment is understood in particular as a position of the respective spiral component in which a central axis of the respective spiral component, and thus its spiral walls, do not run exactly parallel to the rotational axis of the drive shaft.
• the measuring device can comprise at least one contactless distance sensor, for example, an eddy current sensor.
• a distance sensor can be a component of an actuating device, e.g., an active magnetic bearing.
• the spiral walls of the movable scroll component and the spiral walls of the stationary scroll component each have no separate sealing element, i.e., no tip seals, on their end faces facing away from the scroll base.
• the ability to adjust the axial gap between the two scroll components can generally be advantageous even when tip seals are present. Accordingly, in some embodiments, it can be provided that the spiral walls of the movable scroll component and the spiral walls of the stationary scroll component are each provided with a separate sealing element on their end face facing away from the scroll base.
• the adjustability of the axial gap in a scroll vacuum pump with tip seals can, for example, be advantageous in order to ensure less wear or more even wear of the tip seals. Adjusting the axial gap can also be or include an alignment of the scroll components, for example to correct tilting or axial runout. This is also advantageous with regard to less or more even wear of the tip seals.
• hybrid configurations are also possible, i.e., the spiral walls of one spiral component may not have a separate sealing element on their end facing away from the spiral base, while the spiral walls of the other spiral component may be provided with a separate sealing element on their end facing away from the spiral base.
• both configurations are conceivable, i.e., the stationary spiral component may be provided with TipSeals while the movable spiral component may not have TipSeals, or vice versa.
• the scroll vacuum pump comprises a pump housing and an adjusting means which is designed to adjust an axial gap dimension present between the two spiral components, in particular for compensating for misalignments, wherein the adjusting means comprises at least one annular wedge disk which is arranged between the fixed spiral component and the pump housing.
• wedge disks are available as standard components.
• the adjusting means may comprise two annular wedge disks. This allows the relative orientation between the stationary spiral component and the pump housing to be adjusted as desired.
• n with n > 2 wedge disks is provided, at least some of which differ from each other with regard to their profile.
• the set may comprise at least one pair of wedge disks with the same wedge angle. As already mentioned elsewhere, two such wedge disks, with appropriate relative orientation, allow for a purely axial offset between the volute casing and the pump housing.
• a pure axial offset can also be achieved by having the set comprise at least one wedge disk with a wedge angle of 0°.
• the set comprises several wedge disks with a wedge angle of 0°, at least some of which differ from one another in terms of their axial height.
• the set of wedge disks can therefore comprise one or more non-wedge-shaped rings.
• the stationary spiral component, the wedge disks, and the pump housing can be arranged directly against each other with their respective axial end faces. Additional intermediate elements are therefore not required.
• the scroll vacuum pump comprises an adjusting means which is designed to adjust an axial gap dimension present between the two spiral components, in particular to compensate for misalignments, wherein the adjusting means comprises at least one adjusting pin, wherein the adjusting pin mechanically loads the movable spiral component at its rear side in the axial direction.
• the movable spiral component can be moved in the axial direction or tilted with respect to the axis of rotation.
• adjustment pins are provided, distributed around the rotational axis, each of which mechanically loads the movable spiral component at its rear side in the axial direction. It is particularly provided that the adjustment pins can each be actuated independently of one another. The adjustment pins can be evenly distributed around the rotational axis.
• the or each adjusting pin mechanically loads the movable spiral component via at least one axial bearing.
• An axial bearing can be provided for the or each adjusting pin.
• a common axial bearing is provided for at least two adjusting pins, in particular for all adjusting pins.
• the or each thrust bearing may be a rolling bearing.
• a cage can be arranged at the free end of each adjusting pin facing the movable spiral component, in which cage a rolling element, in particular a ball, is held.
• a surface, in particular a flat one, is provided for this rolling element on the rear side of the movable spiral component, with which the rolling element interacts.
• the or each axial bearing is arranged within a corrugated bellows arranged between the movable spiral component and the pump housing.
• the thrust bearing(s) Due to their location within the bellows, the thrust bearing(s) are located in the atmospheric region and thus not in the vacuum zone of the scroll vacuum pump. This allows the use of a lubricated rolling bearing for the thrust bearing(s) without the risk of the lubricant contaminating the vacuum zone.
• the or each adjusting pin may extend within a bellows arranged between the movable scroll component and the pump housing. This prevents the adjusting pin(s) from interfering with the vacuum area of the scroll vacuum pump located outside the bellows.
• an axial bearing is provided for the or each adjusting pin, via which the movable spiral component is mechanically loaded in the axial direction on its rear side, then it can preferably be provided that both the or each adjusting pin and the at least one axial bearing are arranged within the corrugated bellows. This makes it possible for the adjusting means to operate completely separately from the vacuum area of the scroll vacuum pump.
• the or each adjusting pin is supported on the pump housing and can be changed in its effective length between the movable spiral component and the pump housing by actuation.
• the adjusting pin can, for example, be provided with an external thread, at least in the area of the pump housing, which interacts with an internal thread of a bore formed in the spiral casing for the adjusting pin.
• the or each adjustment pin can be actuated from outside the pump housing, in particular during operation of the scroll vacuum pump. This provides a particularly convenient adjustment option, which is also available during operation of the scroll vacuum pump.
• the fixed scroll member and/or the movable scroll member comprises an emergency running means which is designed to prevent direct contact between the fixed scroll member and the movable scroll member in the event of a disturbance of the normal operation, in particular in the event of a wobble of the movable scroll member.
• the emergency running agent may comprise a plurality of individual emergency running agents distributed in the circumferential direction, in particular uniformly.
• the or each emergency running means is designed to come into contact with one spiral component before the other spiral component can come into contact with the one spiral component.
• the or each emergency running means comprises an emergency running element which projects from a surface of one spiral component towards the other spiral component.
• the emergency running element can be at least partially spherical in shape and in particular designed as a ball.
• the emergency running element consists of a ceramic material.
• the or each emergency running means is designed such that a position of the emergency running element relative to the respective other spiral component can be adjusted.
• the or each emergency running means can thus be adapted to a respective axial gap dimension between the two spiral components.
• the emergency running element is mechanically prestressed in the direction of the other spiral component.
• the emergency running means may comprise a bore in the one spiral component, into which the emergency running element and a prestressing device, in particular a compression spring, are received, which mechanically prestresses the emergency running element in the direction of the other spiral component.
• a seat element for the emergency running element can be arranged, by which the position of the emergency running element in the bore is determined.
• the or each emergency running means is attached to the one spiral component and the other spiral component is provided with a, in particular radially outwardly, circumferential counter-section for the emergency running means, which is designed to be in contact with the emergency running means before the two spiral components can come into contact with each other.
• a radially outer circumferential collar can be formed on the other scroll component. Any existing installation space within the scroll vacuum pump can be used for such a circumferential collar.
• the or each emergency running medium can be arranged radially on the outside of one scroll component. This makes it possible to arrange the emergency running concept radially outside the components of the two scroll components that interact with each other for pumping. This eliminates the need for structural modifications to the interacting components.
• the or each emergency running means is attached to a holding section which projects radially outwards from the respective spiral component.
• a radially outwardly projecting section e.g., a tab-like section
• a radially outwardly projecting section may be sufficient.
• Completely circumferential structures on the respective spiral component are therefore not required for the emergency running device(s). Any existing installation space can be used for one or more such retaining sections.
• the drive shaft comprises a hollow shaft section or is designed as a hollow shaft, and at least one bearing point for the rotary mounting of the drive shaft is located in the interior of the drive shaft (first sub-aspect), and/or that the diameter of the eccentric section is more than 1/10, preferably more than 1/8, particularly preferably more than 1/5, of the diameter of the movable spiral component (second sub-aspect), and/or that the axial length of a flange bearing of the movable spiral component is greater than 0.8 times, preferably greater than 1.2 times, the axial height of the movable spiral component (third sub-aspect) or greater than 0.8 times, preferably greater than 1.2 times, the axial height of a spiral arrangement of the movable spiral component comprising at least one spiral wall (fourth sub-aspect), and/or that the axial length of a flange bearing of the movable spiral component is greater than a quarter of the diameter of the movable spiral component (fifth
• the diameter of the eccentric section is more than 1/10, preferably more than 1/8, particularly preferably more than 1/5, of the diameter of the movable spiral component, which increases the rigidity of the eccentric section.
• the third, fourth, and fifth sub-aspects result in a flange bearing with a comparatively large axial length. This, in turn, makes it possible to increase the axial guide length of the flange bearing at the eccentric section.
• the drive shaft is rotatably mounted on a bearing section located in the hollow shaft section or in the hollow shaft, which is a component of a pump housing or which is a pump housing.
• the bearing section can be an integral part of the pump housing.
• the bearing section can extend from an end of the drive shaft facing away from the movable spiral component into the hollow shaft section or into the hollow shaft.
• At least the eccentric section of the drive shaft is designed as a hollow shaft. It is also possible for the entire drive shaft, including the eccentric section, to be designed as a hollow shaft.
• the at least one bearing point located inside the drive shaft for the rotary mounting of the drive shaft is located inside the eccentric section of the drive shaft, wherein a flange bearing of the movable spiral component is rotatably mounted on the outside of the eccentric section.
• the flange bearing of the movable spiral component can pivot on the outside of the eccentric section without being interfered with by the drive shaft's pivot bearing.
• this makes it possible to achieve a comparatively large axial guide length for the flange bearing on the outside of the eccentric section.
• At least one bearing point for the rotary mounting of the flange bearing on the outside of the eccentric section can be axially further away from the movable spiral component than the at least one bearing point for the rotary mounting of the drive shaft located inside the drive shaft. This results in an axial overlap of the bearings of the drive shaft on the one hand and the flange bearing on the other hand on the eccentric section.
• the axial distance between two bearing points for the rotary mounting of a flange bearing of the movable spiral component on the outside of the eccentric section is greater than one fifth of the diameter of the movable spiral component.
• the scroll vacuum pump comprises an adjusting means which is designed to adjust an axial gap dimension present between the two spiral components, in particular to compensate for misalignments, wherein the adjusting means comprises a centrifugal force device by means of which a rotation of the drive shaft can be converted into an axial adjusting movement of the movable spiral component.
• This concept makes it possible to use the rotation of the drive shaft to adjust the axial gap.
• this concept makes it possible to change the axial gap by changing the speed.
• other operating parameters of a scroll vacuum pump can also be influenced by changing the speed, for example, the suction capacity of the scroll vacuum pump.
• this fifth aspect of the present disclosure can exploit the fact that not all operating parameters that change with speed are equally sensitive to speed changes.
• the suction capacity of the scroll vacuum pump changes at least substantially linearly with speed
• the axial gap dimension changes at least substantially quadratically with speed if a centrifugal force device according to the fifth aspect of the present disclosure is provided.
• a desired setting of the axial gap dimension can be achieved without this speed change adversely disrupting the operation of the scroll vacuum pump.
• an actuating force caused by the centrifugal force device acting on the movable spiral component to generate the axial actuating movement is dependent on the speed of the drive shaft.
• the centrifugal force device may comprise a return device whose return force is opposite to the actuating force.
• a control device may be provided that is designed to adjust the rotational speed of the drive shaft such that the forces acting on the movable scroll member in the axial direction cancel each other out. These forces also include the gas pressure acting on the movable scroll member in the axial direction.
• the centrifugal force device comprises a plurality of centrifugal force elements distributed, in particular evenly, around the axis of rotation and a cage for the centrifugal force elements which is connected in a rotationally fixed manner to the drive shaft, which cage enables a movement of the centrifugal force elements with a radial component and has a contact surface for the centrifugal force elements which is designed such that when the drive shaft rotates, the centrifugal force elements moving with the radial component are each additionally deflected in the axial direction.
• the deflection of the centrifugal force elements can be towards the movable spiral component or away from the movable spiral component.
• the contact surface for a respective centrifugal force element defines a path along which the centrifugal force element can be moved with a radial component.
• the path can be designed such that – in the reference system of the rotating components of the centrifugal force device, in particular a cage for the centrifugal force elements – the movement of the centrifugal force element has no circumferential component, i.e., the movement of the centrifugal force element occurs in a single plane containing the axis of rotation.
• the path can be rectilinear. All paths then lie on a cone having the axis of rotation as its central axis. Alternatively, the path can be curved.
• the centrifugal force device comprises a transmission device acting between the centrifugal force elements and the movable spiral component, which transmits the movement of the centrifugal force elements in the axial direction to the movable spiral component.
• the transmission device can be designed such that the deflection of the centrifugal force elements occurs in the same direction as the axial adjusting movement of the movable spiral component caused by the centrifugal force device.
• the transmission device can be movable in the axial direction relative to the cage. It can be provided that the transmission device is movable in the axial direction relative to the cage against a restoring force of a restoring device.
• the restoring device can comprise one or more restoring elements, in particular springs, arranged between the transmission device and the cage.
• the transmission device is carried by the cage.
• the transmission device can be attached to the cage by means of a restoring device, against the restoring force of which the transmission device can be moved in the axial direction relative to the cage.
• the transmission device can be arranged between the cage and the movable scroll member.
• the transmission device can extend in the axial direction from one side of the cage facing away from the movable scroll member to the other side of the cage facing the movable scroll member.
• the transmission device may comprise a plate through which the drive shaft is passed.
• An axial bearing may be provided between the transmission device and the movable spiral component.
• the axial bearing may comprise a plurality of bearing elements, in particular balls, arranged on the movable spiral component or on the transmission device.
• the bearing elements may be distributed, in particular evenly, around the axis of rotation.
• the centrifugal elements can be balls or rollers.
• the spiral components each comprise a spiral arrangement with spiral walls, spiral grooves delimited by these and a spiral base forming the base thereof, as well as a support for the spiral arrangement, wherein an elongated sealing element is arranged between the end face of at least one spiral wall of one spiral component and the spiral base of the other spiral component, and/or vice versa, wherein the Sealing element comprises a contact section for the end face of the spiral wall, a contact section for the spiral base and a web section connecting the two contact sections to one another, and wherein the contact sections bear sealingly against the end face and against the spiral base and the web section is deformable such that during operation the two contact sections are movable relative to one another in accordance with the relative movement between the two spiral components.
• This concept therefore provides a sealing element to seal a volume (conveying chamber) defined by two adjacent spiral walls from adjacent areas.
• this sealing element is not a TipSeal that is simply fixed to the end face of a spiral wall, but rather a sealing element that interacts with both spiral components simultaneously: firstly, with the end face of a spiral wall and secondly, with the spiral base opposite this end face.
• the sealing element which comprises, on the one hand, the two contact sections for the end face of the spiral wall and the spiral base, and, on the other hand, the deformable web section that connects the two contact sections.
• the deformability of the web section enables relative movement between the two spiral components, i.e., the orbiting of the movable spiral component relative to the stationary spiral component, without compromising the sealing contact of the contact sections against the end face of the spiral wall and the spiral base.
• the sealing element can extend over the entire length of a respective spiral wall, in particular over the entire pumping length of the respective spiral wall. Alternatively, the sealing element can extend only over part of the length of the respective spiral wall.
• the sealing element may be a profile element which has the same cross-sectional shape in a cutting plane perpendicular to the longitudinal extent over its entire longitudinal extent, optionally with the exception of the end sections.
• the contact sections can be fixed to the front side and to the spiral base.
• At least one, in particular each, of the contact sections is designed as a suction bar which is shaped in such a way that by pressing the suction bar against a holding surface of the end face or the spiral base, a negative pressure can be generated in a volume delimited by the suction bar and the holding surface and thereby the sealing element is fixed to the holding surface by means of the suction bar.
• This type of suction fixation can be provided either at the base of the spiral or at the front end. This can potentially take advantage of the fact that the base of the spiral is already a flat surface, making it suitable as a holding surface for the sealing element's suction bar.
• the front end of a spiral wall is comparatively narrow, it can serve as a holding surface for a suction bar or be designed as such a holding surface.
• the contact section of the sealing element intended for attachment to the spiral base can be designed as a suction bar.
• the other contact section can then be connected to the end face of the spiral wall in another way. cooperate to enable a sealing arrangement, particularly a fixation, at the front end. This will be discussed in more detail elsewhere.
• the suction bar has a profile formed by two sealing lips in a cross-section perpendicular to the longitudinal extent, which has a shape open towards the front side or the spiral base, in particular a concave shape, preferably a U- or V-shape.
• the retaining surface can be formed by the bottom of a recess formed in the end face or the spiral base.
• the recess can, in particular, be designed as a groove. This makes it possible for one or both contact sections to be arranged at least partially in a recess. This creates more space for the sealing element in the axial direction. At the same time, this allows for the positioning of the respective contact section.
• the holding surface is provided with a boundary on at least one side, in particular on both sides.
• At least one, in particular each, of the contact sections has a profile formed by two sealing lips in a cross-section perpendicular to the longitudinal extent, in particular wherein the profile has a shape open towards the end face or the spiral base, in particular a concave shape, preferably a U- or V-shape.
• This profile can, as already mentioned, form a suction strip. However, this is not mandatory.
• the profile formed by the two sealing lips can also serve for another sealing function of the installation section.
• the two sealing lips can form a clamping strip, so that the The contact section can be attached to the front side of the spiral wall in order to fix the sealing element.
• the shape of the profile formed by the two sealing lips can be selected such that a pressure difference between the two sides separated by the sealing element reinforces the sealing effect of the contact section. According to the concept of self-locking, it can thus be achieved that a force acting due to the pressure difference does not endanger the sealing effect, but rather strengthens it.
• the contact section can be secured to the front side by the sealing lips enclosing the front side.
• the contact section for the end face of the spiral wall is designed as a clamping strip which is shaped in such a way that by plugging the clamping strip onto the end face, the sealing element is fixed to the end face by means of the clamping strip.
• the contact section for the end face can have two sealing lips that can be moved from a neutral position into a clamping position by being pressed apart against a restoring force.
• the smallest distance between the sealing lips is smaller than the largest width of the spiral wall in the area of the end face.
• the web section connecting the two contact sections to one another can be strip-shaped, in particular as a flat strip, and in particular have a rectangular profile in a cross-section perpendicular to the longitudinal extent, the short side of which measured in the radial direction is substantially smaller than the long side of which measured in the axial direction.
• the two contact sections and the web section are formed integrally with one another.
• the contact sections and the web section can be made of the same material or of different materials.
• the sealing element consists of an elastomer material.
• the scroll vacuum pump comprises a pretensioning device for the stationary spiral component, which pretensions the stationary spiral component in the direction of the movable spiral component, and an adjusting means which is designed to adjust an axial gap dimension present between the two spiral components, in particular for compensating for misalignments, wherein the adjusting means comprises at least one actuator which is arranged between a pump housing and the stationary spiral component and is designed to mechanically act on the stationary spiral component relative to the pump housing in the axial direction against a restoring force of the pretensioning device.
• the stationary spiral component is therefore not firmly connected to the pump housing in the axial direction. Rather, a floating bearing of the stationary spiral component is realized in that the preloading device allows the stationary spiral component to be acted upon by at least one actuator relative to the pump housing, counteracting the restoring force of the preloading device.
• the stationary spiral component may be provided in addition to a separate base on which the preloading device is axially supported.
• this base may be formed by a cover of the pump housing.
• the fixed spiral component itself can be designed as a cover of the pump part, wherein the fixed spiral component is mounted on the pump housing both in a sealing manner and in an axially movable manner against the restoring force of the pretensioning device.
• the stationary spiral component is mounted in a floating manner on the separate base.
• the stationary spiral component is mounted in a floating manner on the pump housing.
• a sealing arrangement between the stationary spiral component and the pump housing can be designed to allow axial movement of the stationary spiral component against the restoring force of the preloading device.
• the preloading device can be formed by the sealing arrangement itself.
• the pretensioning device is supported axially on a base, then it can be provided in particular that the base is arranged fixed in the axial direction with respect to the pump housing.
• the base can be formed as a separate component and attached to the pump housing.
• the base can be a component, particularly an integral component, of the pump housing.
• the fixed spiral component is movable relative to the base in the axial direction by means of the actuator against the restoring force of the pretensioning device.
• the base is formed by a cover of the pump housing.
• the fixed spiral component can be guided axially on the base.
• it can be provided that the fixed spiral component is centered on the base.
• the pretensioning device can comprise a plurality of elastically deformable pretensioning elements, in particular compression springs, distributed in particular evenly around the axis of rotation.
• the adjusting means comprises a plurality of actuators, in particular evenly distributed around the axis of rotation, which actuators are each arranged between the pump housing and the stationary spiral component and are designed to mechanically act on the stationary spiral component relative to the pump housing in the axial direction against the restoring force of the pretensioning device, wherein the actuators can be controlled by means of a control device of the adjusting means either jointly or independently of one another in such a way that the axial gap dimension between the two spiral components is adjusted.
• a position of the fixed spiral component brought about by the adjusting means can be fixed in the axial direction.
• the adjusting means can comprise an additional adjusting device which comprises at least one actuator between a base axially supporting the pretensioning device and the fixed spiral component, which actuator is designed to mechanically actuate the fixed spiral component relative to the base in the axial direction away from the base.
• the additional adjusting device enables the position of the fixed spiral component to be fixed without the position of the fixed spiral component being determined during operation by an equilibrium of forces, namely an equilibrium between the gas pressure acting on the fixed spiral component in one direction and the restoring force of the pretensioning device acting in the opposite direction.
• a control device may be provided which is designed to determine an actuator reference position, starting from which a respective desired axial gap adjustment is carried out.
• control device can be designed to control the actuating means in such a way that, starting from an initial position of the fixed spiral component, when the fixed spiral component is acted upon by the pretensioning device but not by the actuator or actuators and is in contact with the movable spiral component, the fixed spiral component is first acted upon by the actuator or actuators to determine an actuator reference position and then, starting from this actuator reference position, is acted upon by means of the actuator or actuators against the restoring force of the Preloading device is moved away from the movable spiral component in order to set a respective desired axial gap.
• control device can be designed to maintain or change the axial gap at a respective desired value during pumping operation by means of the actuator(s) as a function of a force equilibrium which is also influenced by the gas pressure in the pumping system.
• control device can be designed to maintain or change the axial gap at a respective desired value during pumping operation without being influenced by the gas pressure in the pumping system by fixing a respective position of the stationary spiral component in the axial direction by means of an additional adjusting device.
• the or each actuator may comprise a piezo actuator, a servo motor or an active magnetic bearing.
• the scroll vacuum pump comprises an adjusting means which is designed to adjust an axial gap dimension present between the two spiral components, in particular for compensating for misalignments, wherein the adjusting means for acting on a component in the axial direction comprises at least one active axial magnetic bearing, wherein a measuring device is provided which is designed to measure the axial gap dimension at one or more points, in particular continuously during pumping operation, and wherein a control device is provided which is designed to control the magnetic bearing in dependence on the measured axial gap dimension in order to set a target value for the axial gap dimension, in particular within the framework of a control system.
• An active magnetic bearing is a magnetic bearing in which a variable bearing force can be generated using controlled electromagnets.
• Active axial magnetic bearings are used, for example, as axial bearings for the rotors of turbomolecular vacuum pumps. Controlling such magnetic bearings is comparatively simple and can be implemented within a closed-loop control system in which the current axial gap dimension is measured as the actual value.
• the control device can be designed to maintain a constant axial gap dimension during operation by means of a control which serves to compensate for changing operating parameters of the scroll vacuum pump.
• control device is designed to change one or more operating parameters of the scroll vacuum pump by changing the axial gap. This approach is therefore not about compensating for changing operating parameters with the aim of maintaining a constant axial gap, but rather, conversely, about specifically influencing one or more operating parameters of the scroll vacuum pump by changing the axial gap.
• control device can be designed to carry out a calibration in which an axial reference position, in particular an end position, is approached and measured by controlling the magnetic bearing, with respect to which the axial gap dimension is regulated to the desired value during operation.
• the component that is acted upon by the active axial magnetic bearing can, in principle, be chosen arbitrarily.
• the magnetic bearing can be arranged between the two scroll components, between the stationary scroll component and the pump housing, between the movable scroll component and the pump housing, or between an abutment and the drive shaft or a component connected to the drive shaft.
• a preloading device can be provided for the component, against whose restoring force the magnetic bearing acts on the component.
• the fixed spiral component, the movable spiral component and the drive shaft are arranged successively in the axial direction.
• an electric drive motor for the drive shaft is arranged on the side of the movable spiral component facing away from the fixed spiral component.
• the movable spiral component has a flange bearing, via which the movable spiral component is rotatably mounted on the eccentric section of the drive shaft, and wherein the flange bearing is arranged on the side of the movable spiral component facing away from the fixed spiral component.
• the fixed spiral component is designed as a cover of a pump housing.
• the spiral components each comprise a spiral arrangement with spiral walls and spiral grooves delimited by these, wherein in each case one or more, preferably exactly two, radially outer spiral walls lie on concentric circles and are interrupted in the circumferential direction, whereby a parallel pumping structure of parallel channels is formed, which merge into at least one, preferably exactly one, radially inner pumping channel, which is formed by a spirally extending spiral groove and delimited by a spirally extending spiral wall.
• a measuring device is provided which is designed to measure the axial gap dimension at one or more locations, in particular continuously during pump operation.
• the spiral walls of the movable spiral component and the spiral walls of the fixed spiral component do not have a separate sealing element on their end face facing away from the spiral base.
• the present disclosure also relates to a method for operating a scroll vacuum pump with a pumping system comprising a stationary spiral component and a movable spiral component cooperating with the latter in a pumping-effective manner, a drive shaft rotating about a rotational axis during operation and having an eccentric section for driving the movable spiral component, a pump housing, a pretensioning device for the stationary spiral component, which pretensions the stationary spiral component in the direction of the movable spiral component, and an adjusting means configured to adjust an axial gap dimension present between the two spiral components, in particular to compensate for misalignments, wherein the adjusting means comprises at least one actuator, which is arranged between the pump housing and the stationary spiral component and is designed to mechanically load the stationary spiral component relative to the pump housing in the axial direction against a restoring force of the pretensioning device, and wherein the method comprises first determining an actuator reference position, starting from which a respectively desired axial gap setting is then carried out.
• the actuating means is controlled in such a way that, starting from an initial position of the fixed spiral component when the fixed spiral component is acted upon by the pretensioning device but not by the actuator or actuators and is in contact with the movable spiral component, said fixed spiral component is first acted upon by the actuator or actuators to determine the actuator reference position and then, starting from this actuator reference position, is moved away from the movable spiral component by means of the actuator or actuators against the restoring force of the pretensioning device in order to set a respective desired axial gap.
• the axial gap is maintained or changed at a respective desired value by means of the actuator(s) depending on a force balance which is also influenced by the gas pressure in the pumping system.
• the axial gap is maintained or changed at a respective desired value without being influenced by the gas pressure in the pumping system by fixing a respective position of the stationary spiral component in the axial direction by means of an additional adjusting device.
• the method described above can be carried out in particular with a scroll vacuum pump according to the seventh aspect of the present disclosure.
• Fig. 1 shows a conventional scroll vacuum pump with a basic structure, which is described below.
• the structure and operation of such a scroll vacuum pump are known to those skilled in the art.
• This conventional scroll vacuum pump can be further developed in various ways according to the present disclosure. Various aspects of the present disclosure are then explained with reference to the Fig. 2 to 8 explained.
• the scroll vacuum pump according to Fig. 1 comprises a pumping system with a stationary spiral component 11 and a movable spiral component 13, which cooperate in a pumping manner during operation. Furthermore, the scroll vacuum pump comprises a drive shaft 17, which rotates about a rotational axis 15 during operation and has an eccentric section 19 for driving the movable spiral component 13. Furthermore, the scroll vacuum pump is provided with an electric drive motor 21, 23, which serves to set the drive shaft 17 in rotation about the rotational axis 15.
• the electric drive motor comprises a radially inner Motor rotor 21, also called runner, and a radially outer motor stator 23.
• the drive shaft 17 is rotatably mounted on the pump housing 41 at two axially spaced bearing points 25, 27.
• the front bearing point 25 is formed by a front roller bearing designed as a fixed bearing, while the rear bearing point 27 is formed by a rear roller bearing designed as a floating bearing.
• the pump housing 41 is provided with a sleeve-shaped section, which is also referred to below as bearing sleeve 115.
• the two roller bearings 25, 27 are thus located radially between the drive shaft 17 and the bearing sleeve 115.
• Both bearing points 25, 27 are located on the side of the drive motor 21, 23 facing the eccentric section 19 of the drive shaft 17. Thus, all bearing points 25, 27 are located within the pump housing 41 in front of the drive motor 21, 23. The bearing points 25, 27 are located in the atmospheric region of the pump, i.e., not in the region in which a vacuum prevails during pumping operation.
• the eccentric section 19 is integrally connected to the front end of the drive shaft 17, and the drive motor 21, 23 sits on the rear end of the drive shaft 17. This design allows the drive motor 21, 23 to be pushed onto the rear end of the drive shaft 17. This simplifies the assembly and replacement of the drive motor 21, 23 or parts of the drive motor 21, 23.
• the balancing concept for balancing the rotating system which includes, among other things, the drive shaft 17 and the movable spiral component 13, comprises a front balancing weight 29 and a rear balancing weight 31, which are attached to the drive shaft 17.
• the front balancing weight 29 is arranged in the region of the front end of the drive shaft 17 and the eccentric section 19.
• the rear balancing weight 31 is located in front of the rear bearing point 27 and thus in front of the drive motor.
• the rear balancing weight or an additional balancing weight can be located at the rear end of the drive shaft near the drive motor.
• a pressure element 87 is provided which is placed on the front side of the rear end of the drive shaft 17 and which is rotationally symmetrical and does not serve as a balancing weight.
• the pressure element 87 is connected to the drive shaft 17 by means of a central screw 83.
• the rear section of the drive shaft 17 is provided with a sleeve element 33.
• the sleeve element 33 is clamped to the motor rotor 21 by means of the pressure element 87 and the central screw 83.
• the sleeve element 33 is fastened to the drive shaft 17 by means of a positioning pin 33a.
• an annular intermediate element 34 is arranged axially between a shoulder 17a formed on the drive shaft 17 and the motor rotor 21.
• the motor rotor 21 is clamped via the intermediate element 34 between the pressure element 87 and the shoulder 17a of the drive shaft 17, which serves as an abutment for the intermediate element 34.
• a wave spring 99 is arranged between the loose bearing 27 forming the rear bearing point 27 and the intermediate element 34.
• the drive motor 21, 23 is arranged completely within the pump housing 41, ie the drive motor 21, 23 is surrounded by the pump housing 41 in the circumferential direction over its entire axial length, is not At its rear end, the pump housing 41 is closed by a separate motor cover 103.
• the fixed spiral component 11 also referred to as the spiral housing, is screwed onto the front end of the pump housing 41 and is surrounded by a hood 105, which is also attached to the pump housing 41 and in which a fan 95 is also housed.
• the movable spiral component 13 is mounted on the eccentric section 19 via a flange bearing 91 designed as a rolling bearing.
• a thrust washer 93 is located axially between the movable spiral component 13 and the eccentric section 19.
• a shim 94 is located between a circumferential shoulder of the drive shaft 17 at the transition to the eccentric section 19 and the flange bearing 91.
• the correct alignment in the circumferential direction between the stationary spiral component 11 and the pump housing 41 is ensured by a positioning pin 97.
• multiple positioning pins 79 can also be provided.
• the stationary spiral component 11 comprises a spiral arrangement with spiral walls 49 and spiral base 51, as well as a support 53 for the spiral arrangement, the side of which facing the movable spiral component 13 forms the spiral base 51.
• two radially outer spiral walls 49 can be provided, which lie on concentric circles and are interrupted in the circumferential direction. This creates a parallel pumping structure consisting of parallel pumping channels formed by the respective spiral grooves between the spiral walls 49, which merge into a spiral-shaped, radially inwardly extending pumping channel formed by a spiral spiral groove and delimited by a spiral spiral wall 49.
• the movable spiral component 13 also comprises a spiral arrangement with spiral walls 69 and a spiral base 71, as well as a plate-shaped support 73 for the spiral arrangement, the side of which facing the stationary spiral component 11 forms the spiral base 71.
• two radially outer spiral walls 69 can be provided, which lie on concentric circles and are interrupted in the circumferential direction in the region of a gas inlet (not shown).
• a radially inner spiral wall 69 extends spirally.
• Both the spiral walls 49 of the fixed spiral component 11 and the spiral walls 69 of the movable spiral component 13 are provided with an elongated sealing element 75 (TipSeal) at their ends facing away from the respective spiral base 51 or 71.
• spiral arrangements of the two spiral components 11, 13 described above can also be designed differently.
• the gas to be pumped enters the pumping system comprising the two spiral components 11, 13 via an inlet flange 77 and is expelled via an outlet flange (not shown).
• the pump housing 41 is supported on a base formed by an electronics housing 43.
• the pump housing 41 is screwed to the electronics housing 43.
• the electronics housing 43 which is not shown in full, is provided with feet (not shown) on its underside.
• the electronics housing 43 houses electronic equipment comprising electronic, electrical, and electromechanical components that serve, among other things, to supply power to and control the scroll vacuum pump.
• the scroll vacuum pump also includes a gas ballast valve (not shown).
• a gas ballast valve (not shown).
• a multi-stage gas ballast system can be provided instead of a gas ballast valve.
• the eccentric drive formed by the drive shaft 17 with the eccentric section 19 is located within the pump housing 41 and is surrounded by a deformable sleeve in the form of a bellows 89.
• the bellows 89 serves, on the one hand, to seal the eccentric drive from the suction area of the scroll vacuum pump and, on the other hand, to prevent rotation of the movable spiral component 13.
• the bellows 89 is attached to the side of the movable spiral component 13 facing the drive.
• the rear end of the bellows 89 is attached to a housing base within the pump housing 41 by means of screws.
• an axial gap exists between the end faces of the spiral walls 49 and 69 of one spiral component 11 and 13, respectively, and the spiral base 71 and 51 of the other spiral component 13 and 11, respectively, which is generally referred to as the axial gap dimension in the context of this disclosure.
• the axial gap dimension influences the vacuum performance of the scroll vacuum pump and thus, in particular, its suction capacity and the minimum ultimate pressure that can be achieved with the scroll vacuum pump.
• Some aspects of the present disclosure each provide a possibility for adjusting the axial gap dimension, depending on the embodiment, either during pumping operation or outside of pumping operation. Some embodiments allow the axial gap dimension to be adjusted optionally during pumping operation or outside of pumping operation. Different possibilities for adjusting the axial gap dimension, as well as further aspects of the present disclosure, are explained below in conjunction with the figures, wherein these individual aspects are illustrated using the example of a conventional scroll vacuum pump. which has a basic structure as described above with reference to Fig. 1 In the figures described below, these aspects are largely presented purely schematically in order to explain the respective concept.
• an adjusting means comprises two identical wedge disks 111, 113.
• the pump housing 41 and the spiral housing 11 serving as a cover for the pump housing 41 are shown in the scroll vacuum pump.
• Fig. 2a shows the scroll vacuum pump in a perspective view.
• Fig. 2b shows a side view.
• the two wedge disks 111 and 113 are identical in design, i.e., they have the same profile. Accordingly, both wedge disks 111 and 113 have a cylindrical base of height h and a wedge angle ⁇ .
• a corresponding relative position between the two wedge disks 111, 113 can produce a pure axial offset between the spiral casing 11 and the pump casing 41, which corresponds to the sum of the base height h, i.e. the minimum height, and the maximum height H.
• This situation is in Fig. 2b shown.
• this relative position according to Fig. 2b is referred to as a neutral position, then starting from this neutral position, by rotating the two wedge disks 111, 113 relative to each other, an inclination of the spiral casing 11 relative to the pump casing 41 can be brought about or an inclination caused, for example, by manufacturing can be corrected.
• the adjusting means comprises a plurality of adjusting pins 131 distributed around the rotation axis 15.
• Fig. 3 are two Adjustment pins 131 are shown.
• three adjustment pins 131 are provided, evenly distributed around the rotation axis 15.
• Each adjusting pin 131 extends with its rear end through a bore 135 formed in the pump housing 41.
• this hole is not in the shown section plane and is therefore in Fig. 3 not shown.
• the bores 135 are each provided with an internal thread, to which the respective adjusting pin 131, which has a corresponding external thread, is screwed.
• Each adjusting pin 131 interacts with the rear side of the movable spiral component 13 (orbiter) facing away from the spiral casing (not shown), namely radially outside the flange bearing 91 of the orbiter 13, which is rotatably mounted on the eccentric section 19 of the drive shaft 17 in accordance with the basic structure of the scroll vacuum pump already explained.
• a roller bearing 133 designed as an axial bearing is provided, with which the adjustment pin 131 mechanically loads the rear side of the orbiter 13 with its free end facing the orbiter 13.
• the axial bearings 133 are in Fig. 3 only symbolically represented and in practice designed in such a way that the curved arrows in Fig. 3 indicated orbiting movement of the orbiter 13 around the axis of rotation 15 can be absorbed while maintaining the axial mechanical loading by the adjusting pins 131.
• a pure axial offset of the orbiter 13 along the rotation axis 15 can be set or an inclination of the orbiter 13 can be specifically adjusted or compensated.
• the adjusting pins 131 and the axial bearings 133 are within the Fig. 3
• the bellows 89 which is only schematically illustrated, is arranged.
• the bellows 89 separates the vacuum region of the scroll vacuum pump from the atmospheric region within the bellows 89. This is particularly advantageous since, in particular, the axial bearings 133 are located in the atmospheric region and a lubricant used for these rolling bearings 133 cannot therefore impair the vacuum region of the scroll vacuum pump.
• the Fig. 4a and 4b The embodiment shown does not relate to an adjusting means for adjusting an axial gap between the two spiral components 11, 13, but rather to a measure which prevents contact between the orbiter 13 and the spiral casing 11 in the event of excessive wobble of the orbiter 13 during operation.
• Fig. 4a and 4b an emergency running means comprising a plurality of individual emergency running means 151 distributed around the axis of rotation.
• Fig. 4a shows schematically a possible concrete design of such an emergency running means 151.
• Fig. 4b illustrates a possible installation situation for the individual emergency running agents 151.
• Each emergency running means 151 comprises an axial bore 159 formed in the spiral casing 11, which is open towards the orbiter 13.
• a sleeve 163 is screwed into the bore 159.
• a compression spring 155 extends within the sleeve 163 and is supported on the bottom 165 of the sleeve 163.
• the compression spring carries an emergency running element 153 in the form of a ceramic ball.
• the arrangement of the ball 153 on the compression spring 155 is shown in Fig. 4a merely schematic
• the ball 153 interacts with the compression spring 155 in such a way that the ball 153 can rotate freely.
• a Fig. 4a A holding or bearing element not shown may be provided, for example in the form of a cage for the ball 153.
• the compression spring 155 acts as a preloading device for the ball 153, which is thereby preloaded toward the open end of the bore 159 and pressed against a seat element 157 arranged in the region of the opening of the bore 159.
• the design of the seat element 157 determines, depending on the size of the ball 153, the extent by which the ball 153 protrudes from the bore 159 toward the orbiter 13.
• the preload force acting on the ball 153 via the compression spring 155 can be adjusted by turning the sleeve 163 screwed into the bore 159.
• a circumferential collar 161 is formed radially outwardly on the carrier 73 of the orbiter 13, which serves as a counter-section for the balls 153 of the individual emergency running means 151.
• the embodiment according to Fig. 5 does not concern an adjusting means for adjusting an axial gap between the two spiral components 11, 13. Rather, the embodiment of the Fig. 5 an improvement in the guidance of the Orbiter 13.
• the axial length of the flange bearing 91 of the orbiter 13 is comparatively short.
• the axial length of the flange bearing 91 corresponds to the axial length of the eccentric section 19 of the drive shaft 17, on which the orbiter 13 is rotatably mounted by means of the flange bearing 91.
• the diameter of the eccentric section 19 is comparatively small.
• the guide length and guide diameter for the orbiter 13 on the eccentric section 19 of the drive shaft 17 are thus relatively small.
• the drive shaft 17 has a hollow shaft section or - as in Fig. 5 shown - is designed as a whole as a hollow shaft.
• the drive shaft 17 can accommodate a bearing section 175, which is shown here as a cylindrical shaft whose central axis coincides with the rotational axis 15 of the drive shaft 17.
• the bearing portion 175 is shown here as an integral part of the pump housing 41, but may also be a separate component carried by the pump housing 41.
• driven drive shaft 17 takes place at two axially spaced bearing points 173, 183, each of which is formed by a rolling bearing.
• One bearing point 183 is located in the rear region of the drive shaft 17, specifically between the drive shaft 17 and the pump housing 41 and thus outside the drive shaft 17.
• the other bearing point 173, however, is located inside the drive shaft 17, specifically between the inside of the drive shaft 17 and a front section 176 of the bearing section 175 with a reduced diameter.
• Fig. 5 shows only one bearing point 173 within the drive shaft 17.
• several, for example two or three, bearing points arranged spaced apart from one another in the axial direction can also be provided within the drive shaft 17 between the bearing section 175 and the inside of the drive shaft 17.
• Fig. 5 shows - as mentioned - the bearing point 183 provided in the rear area of the drive shaft 17 on the outside thereof, which interacts with the pump housing 41. On the one hand, this bearing point 183 is arranged in the - as mentioned - rear area of the drive shaft 17. On the other hand, such a bearing point provided on the outside of the drive shaft 17 can be omitted.
• the drive shaft 17 is rotatably mounted exclusively on the bearing section 175 extending within the drive shaft 17, in particular via at least two bearing points spaced apart from one another in the axial direction.
• the pivotal mounting of the drive shaft 17 on a bearing section 175 extending within the drive shaft 17 makes it possible, in particular, to design the eccentric section 19 of the drive shaft 17, on which a flange section 177 of the orbiter 13 is mounted by means of the flange bearing 91, to be comparatively long in the axial direction. This results in a huge increase in the guide length of the orbiter 13 on the eccentric section 19 and thus on the drive shaft 17. This, in turn, means a significantly more stable guidance of the orbiter 13, which significantly reduces the tendency of the orbiter 13 to wobble.
• the design of the drive shaft 17 as a hollow shaft saves axial installation space, since the flange bearing 91 for the rotary mounting of the orbiter 13 on the eccentric section 19, on the one hand, and the bearing points 173, 183 for the rotary mounting of the drive shaft 17 on the pump housing 41, on the other hand, do not have to be arranged axially consecutively, but can overlap each other axially.
• the bearing point 173 is located axially closer to the carrier 73 of the orbiter 13 than the rear bearing point 179 of the flange bearing 91.
• FIG. 5 The design example of the scroll vacuum pump is not to scale, but can be Fig. 5
• the size relationships leading to the aforementioned advantageous, relatively large guide length of the orbiter 13 at the eccentric section 19 are explained with respect to the diameter of the orbiter 13.
• the outer diameter of the carrier 73 of the orbiter 13 can be considered as the diameter of the orbiter 13.
• a large axial guide length leading to an avoidance or at least reduction of the wobble of the orbiter 13 can be achieved if the axial length B of the flange section 177 of the orbiter 13 is greater than a quarter of the diameter A of the orbiter 13, and/or if the axial distance C between two bearing points 181, 179 of the flange bearing 91, i.e. between two bearing points 181, 179 for the rotary mounting of the flange section 177 of the orbiter 13 on the outside of the eccentric section 19 of the drive shaft 17, is greater than one fifth of the diameter A of the orbiter 13.
• stable guidance of the orbiter 13 on the eccentric section 19 and thus the avoidance or at least reduction of wobble of the orbiter 13 during operation of the scroll vacuum pump can be achieved by making the diameter of the eccentric section 19 relatively large.
• stable guidance is achieved when the diameter of the eccentric section 19 is more than one-tenth, more than one-eighth, or more than one-fifth of the diameter A of the movable spiral component 13.
• This further sub-aspect for improving the guidance of the orbiter 13 on the eccentric section 19 is also independent of whether the drive shaft 17 is designed entirely or partially as a hollow shaft.
• the adjusting means serves to adjust the axial gap between the orbiter 13 and the spiral casing 11 by applying a force acting in the axial direction to the orbiter 13.
• the adjusting means comprises a centrifugal force device 191 which utilizes the rotation of the drive shaft 15 during operation of the scroll vacuum pump.
• the centrifugal force device 191 is designed such that the force applied axially to the orbiter 13 is The magnitude of the rotational speed of the drive shaft 15 is dependent. This concept makes it possible, in particular, to change the axial gap dimension by changing the rotational speed.
• the actuating means does not specify an absolute axial adjustment path for the orbiter 13; rather, the axial position of the orbiter 13 results from a balance of the forces acting on the orbiter 13 in the axial direction, of which the actuating force of the centrifugal force device 191 is one of the forces involved.
• the forces acting on the orbiter 13 are the aforementioned axial actuating force Fs due to the centrifugal force device 191, described in more detail below, a restoring force Fr of a restoring device 193, which is also described in more detail below, and a force Fd acting in the opposite direction due to the gas pressure in the pump system.
• the centrifugal force device 191 comprises a cage 199 for centrifugal force elements 197 designed as balls.
• the inside of the cage 199 forms a contact surface 201 on which the balls 197 can roll.
• the contact surface 201 lies on a cone whose central axis coincides with the rotation axis 15 and which has a cone angle different from 0°.
• Fig. 6b shows a top view of the ball cage 199 from the right in Fig. 6a . Consequently, several balls 197 are provided, evenly distributed in the circumferential direction, with the cage 199 defining a path for each ball 197—in the reference system of the cage 199—that runs exclusively in a single plane containing the rotational axis 15. Since the centrifugal force elements 197 must each be able to move only along such a path, cylindrical bodies can also be provided as centrifugal force elements 197 instead of the balls 197.
• the tracks 200 each run straight at the cone angle obliquely to the axis of rotation 15.
• a spring 193 is effective in each of the fields between two circumferentially successive tracks 200.
• the springs together form a return device 193.
• the springs 193 are connected at one end to the cage 199 and at the other end to a transmission device 203, which is designed here as a plate with a central opening having a flange portion 204 through which the drive shaft 17 extends.
• the cage 199 is fixedly connected to the drive shaft 17.
• the transmission device 203 is carried by the cage 199, but is movable in the axial direction relative to the cage 199.
• the attachment of the transmission device 203 to the cage 199 can be achieved, for example, via the aforementioned return device 193.
• the rotational drive of the transmission device 203 by the cage 199, ensuring the aforementioned axial relative movement between the cage 199 and the transmission device 203 can be achieved by an engagement between the cage 199 and the transmission device 203 that is effective in the circumferential direction.
• a guide device can be provided, by which the transmission device 203 is guided on the cage 199 in the axial direction.
• the transmission device 203 is thus arranged in the axial direction between the cage 199 and the orbiter 13 and transmits the axial actuating force of the centrifugal force elements 197 to the orbiter 13 during operation of the scroll vacuum pump with the rotating drive shaft 15. Since the transmission device 203 rotates together with the drive shaft 17 and the cage 199 about the rotational axis 15, but the orbiter 13 only orbits, a An axial bearing 205 is provided, which in the embodiment shown here is integrated into the orbiter 13.
• the axial bearing 205 is formed by a ball cage provided radially on the outside of the flange portion 209 of the orbiter 13, in which a plurality of bearing elements 207 designed as balls are held, which have a radial range of motion corresponding to the orbital movement of the orbiter 13 about the rotation axis 15.
• the axial actuating force Fs is determined by the centrifugal force and the cone angle, i.e., the inclination of the rectilinear tracks 200 relative to the rotational axis 15.
• the actuating force Fs can be changed by changing the course of the paths 200. This can be achieved, for example, by a different inclination of the still straight paths 200 or by making the paths 200 curved, as is the case, for example, Fig. 6d shows, ie the contact surface 201 is not as in Fig. 6c on a cone, but on a differently shaped rotational body.
• centrifugal force elements 197 of different masses, since the axial actuating force Fs also depends on the mass of the centrifugal force elements 197.
• the centrifugal force device 199 provided according to this aspect of the present disclosure offers a variety of possibilities for adjusting the axial gap dimension by utilizing the rotation of the drive shaft 17.
• the reset device 193 offers a further adjustment option by changing the reset force acting on the transmission device 203.
• the reset force can be achieved, for example, by using springs 193 with a different spring constant.
• the axial gap dimension is adjusted by the orbiter 13 being moved by means of the centrifugal force elements 197 against the restoring force of the restoring device 193 and against the force Fd acting due to the gas pressure in the direction of the Fig. 6 not shown spiral casing 11, in Fig. 6a i.e. to the left.
• a mirrored arrangement of a centrifugal force device 191 is also possible, with which the orbiter 13 is moved away from the spiral casing 11, into Fig. 6e i.e. to the right.
• the transmission device 203 is designed in such a way, for example in the shape of a pot or cup, that it extends axially past the cage 199 radially outward to the orbiter 13 and is connected to it in a suitable, Fig. 6e can intervene in a manner shown only as an example in order to be able to transmit the actuating force Fs to the orbiter 13.
• the embodiment of the Fig. 7 This does not concern an adjusting device for adjusting the axial gap between the two spiral components 11, 13, but rather a concept for sealing volumes enclosed between the spiral walls 49, 69.
• TipSeals are known for this purpose, which are attached to the end faces of the spiral walls.
• the embodiment of the Fig. 7 relates to an alternative to TipSeals, which ensures a complete seal between the end face 219 of a respective spiral wall 69 and the spiral base 51 opposite this end face 219.
• an elongated sealing element 211 extending over the entire respective end face 219 is used for this purpose.
• the sealing element 211 comprises two contact sections 213, 215, which are connected to one another by a strip-shaped web section 217.
• the sealing element 211 is formed in one piece, ie both the two contact sections 213, 215 and the web section 217 are made of the same material, which—as mentioned—can in particular be an elastomer material.
• the contact sections 213, 215 serve to form a sealing contact with the two spiral components 11, 13.
• One contact section 213 serves to form a sealing contact with the end face 219 of a respective spiral wall 69.
• the other contact section 215 serves to form a sealing contact with the opposite spiral base 51.
• the sealing element 211 is a profile element in that it has the same cross-sectional shape over its entire longitudinal extent in a sectional plane perpendicular to the longitudinal extent. At least one such contact section 213, 215, which serves as a suction strip explained in more detail below, is preferably closed at both ends in order to be able to maintain the negative pressure required for suction fixation.
• the two contact sections 213, 215 can have a different profile.
• the contact section 215 for the spiral base 51 is designed as a suction bar and has one of two sealing lips 221 (cf. Fig. 7a ) formed profile which is open outwards, i.e. in the direction pointing away from the web section 217.
• This sealing section 215 is therefore open towards the spiral base 51 when oriented as intended.
• the sealing lips 221 are shaped such that they form a suction bar which can be pressed against the spiral base 51, so that a negative pressure is generated in the volume delimited by the two sealing lips 221 and the spiral base 51.
• the sealing element 211 is fixed to the spiral base 51 via this contact section 215.
• the spiral base 51 thus forms a holding surface for the contact section 215 designed as a suction bar.
• the profile formed by the two sealing lips 221 can be shaped such that a pressure difference
• the contact section 213 of the sealing element 211 which interacts with the end face 219 of the respective spiral wall 69, is not designed as a suction bar, but as a clamping bar.
• the two sealing lips 221 forming this contact section 213 can be pushed apart against a restoring force by being placed onto the end face 219 of the spiral wall 69, so that the sealing element 211 is clamped to the end face 219 of the spiral wall 69 by means of this contact section 213.
• the contact section 213, with its two sealing lips 221, rests sealingly against the end face 219 of the spiral wall 69.
• the sealing element 211 with its two correspondingly shaped contact sections 213, 215, can be fixed in a sealing manner to the spiral base 51 and to the opposite end face 219, ensuring complete sealing between the two adjacent volumes delimited by the spiral walls.
• the relative movement between the two spiral components 11, 13 due to the orbital movement of the movable spiral component 13 relative to the stationary spiral component 13 is absorbed by the flexible web section 217 of the sealing element.
• the flexibility of the web section 217 required for this purpose can be ensured by the choice of material and the thickness of the web section 217.
• Fig. 7c and 7d show two modifications in which the contact section 213 of the sealing element 211, which interacts with the end face 219 of the spiral wall 69, is also designed as a suction strip.
• the end face is provided with a groove-shaped recess 223, the bottom of which forms a holding surface to which the contact section 213 can be suctioned by pressing it.
• the recess 223 also provides more space for the sealing element 211 in the axial direction. Furthermore, the lateral boundaries 225 of the recess 223 provide additional lateral support for the contact section 213.
• a groove-shaped recess 223 is also provided in the spiral base 51 and thus for the other contact section 215. This provides even more space in the axial direction for the sealing element 211 and also provides additional lateral support for the contact section 215 at the spiral base 51.
• Fig. 8a and 8b show two variants of an embodiment in which the axial gap between the two spiral components 11, 13 can be adjusted by mechanically loading the spiral casing 11.
• the spiral casing 11 is movable in the axial direction relative to the pump casing 41 and is axially supported via a pretensioning device 233 on a base 237 which forms a cover of the pump casing 41 and is firmly connected to the pump casing 41.
• the spiral casing 11 is neither axially fixed relative to the pump housing 41, nor does the spiral casing 11 form a cover for the pump housing 41.
• the spiral casing 11 and base 237 together can be regarded as a fixed spiral casing forming a cover for the pump housing 41, comprising a fixed and a movable component. Nevertheless, the previous terminology will be retained here, i.e., the component 11 provided with the spiral arrangement and thus interacting with the orbiter 13 for pumping purposes will continue to be referred to either as the spiral casing or the fixed spiral component.
• these two components are provided with cylindrical guide sections 239, 241 of different diameters, so that the spiral casing 11 is mounted on the base 237 in an axially displaceable manner.
• Actuators 235 which are only symbolically shown, are each supported on the pump housing 41 and are designed to mechanically load the spiral casing 11 in the axial direction against the restoring force of the restoring device 233.
• the spiral casing 11 is provided radially on the outside with a circumferential collar 245.
• a circumferential collar 245 instead of a circumferential collar 245, several circumferentially distributed, e.g., tab-like Projections may be provided which are circumferentially aligned with the actuators 235 and the springs forming the pretensioning device 233.
• a control device 243 of the scroll vacuum pump is provided for the actuators 235.
• the control device 243 can be provided separately and communicate with a central control device of the scroll vacuum pump.
• the control device 243 can be integrated into such a central control device or be formed by it.
• the spiral casing 11 can be adjusted to a predeterminable axial position relative to the orbiter 13 by means of the actuators 235.
• the actuators 235 then prevent a backward movement of the spiral casing 11 in the direction of the orbiter 13.
• an axial movement of the spiral casing 11 away from the orbiter 13 can occur due to the gas pressure in the pump system, i.e. Fig. 8a to the left.
• the variant according to Fig. 8b ensures independence from the forces acting on the spiral casing 11 during operation.
• An additional actuating device is provided here to fix the desired axial position of the spiral casing 11, which in turn comprises actuators 249, shown only symbolically here, which are effective in a circumferential direction between the base 237 and the spiral casing 11.
• the additional actuators 249 supported on the base 237 can be actuated by means of the control device 243. be activated to pressurize the spiral casing 11 in such a way that the previously set axial position of the spiral casing 11 is maintained.
• the spiral casing 11 is then axially held between the actuators 235 on the one hand and the actuators 249 on the other hand, at the desired axial distance from the orbiter 13.
• the setting of a respective desired axial position of the spiral component 11 can be carried out according to a method according to a further aspect of the present disclosure, which has already been explained in the introductory part.
• a possible embodiment of this method provides that first a reference position of the actuators 235 is determined and then, starting from this reference position, the spiral casing 11 is brought into the respectively desired axial position relative to the orbiter 13 by means of the actuators 235.
• the preliminary assembly of the scroll vacuum pump is carried out in such a way that after the assembly of the Orbiter 13 and bellows 89 assembly in the conventional manner (in Fig. 8a and 8b (only indicated schematically) the individual actuators 235 are mounted on the pump housing 41 in a circumferentially distributed manner.
• the spiral housing 11 is then placed in the rotational position that matches the rotational position of the orbiter 13 and the circumferential positions of the actuators 235.
• the compression springs 233 forming the pretensioning device 233 are then attached in a circumferentially distributed manner to the rear side of the circumferential collar 245 of the spiral housing 11 facing away from the orbiter 13.
• the cover formed by the base 237 is then mounted on the pump housing 41, the centering of the spiral housing 11 being ensured by the two interacting cylindrical guide sections 239, 241.
• the sealing of the pump housing 41 is ensured by a circumferential seal 247, e.g. in the form of an O-ring between the pump housing 41 and the base 237.
• the base 237 is placed on top with the actuators 249 mounted on the inside of the base 237 distributed in the circumferential direction.
• the preloading device 233 ensures that the spiral casing 11 rests axially against the orbiter 13. This situation defines an initial position of the spiral casing 11.
• the spiral casing 11 is therefore acted upon by the preloading device 233, but not by the actuators 235.
• the actuators 235 are activated until they apply axial pressure to the spiral casing 211.
• This situation is detected by the mechanical resistance experienced by the actuators 235.
• This resistance is detected by the control device 243 through an increase in current and thus an increased power consumption of the actuators 235.
• This situation defines a reference position of the actuators 235, which can also be referred to as the axial zero position.
• an absolute dimension for the axial gap between the spiral casing 11 and the orbiter 13 can then be set by controlling the actuators 235 in such a way that they cover a predetermined axial travel distance and in doing so move the spiral casing 11 at the respective circumferential position by this axial travel distance against the restoring force of the pretensioning device 233 away from the orbiter 13.
• the axial position of the spiral casing 11 thus set can be changed, for example, depending on the respective operating conditions by applying either a greater or lesser load to the spiral casing 11 by means of the actuators 235.
• Fig. 8a shows purely by way of example a measuring device 251 which is designed to measure the axial gap dimension between the spiral casing 11 and the orbiter 13, either at one point in the circumferential direction or at several points distributed in the circumferential direction, as in Fig. 8a
• a measuring device 251 can also be used according to the other aspects of the present disclosure in which the axial gap dimension is adjusted.
• the measuring device may comprise a distance sensor or a plurality of distance sensors 251 distributed in the circumferential direction.
• the or each distance sensor 251 may, for example, be designed as an eddy current sensor or comprise a Hall sensor.

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• 2025
  • 2025-09-09 EP EP25201241.4A patent/EP4636251A2/fr active Pending

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