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
  • F04C18/30—Rotary-piston pumps specially adapted for elastic fluids having the characteristics covered by two or more of groups F04C18/02, F04C18/08, F04C18/22, F04C18/24, F04C18/48, or having the characteristics covered by one of these groups together with some other type of movement between co-operating members
  • F04C18/34—Rotary-piston pumps specially adapted for elastic fluids having the characteristics covered by two or more of groups F04C18/02, F04C18/08, F04C18/22, F04C18/24, F04C18/48, or having the characteristics covered by one of these groups together with some other type of movement between co-operating members having the movement defined in group F04C18/08 or F04C18/22 and relative reciprocation between the co-operating members
  • F04C18/344—Rotary-piston pumps specially adapted for elastic fluids having the characteristics covered by two or more of groups F04C18/02, F04C18/08, F04C18/22, F04C18/24, F04C18/48, or having the characteristics covered by one of these groups together with some other type of movement between co-operating members having the movement defined in group F04C18/08 or F04C18/22 and relative reciprocation between the co-operating members with vanes reciprocating with respect to the inner member
  • F04C18/3441—Rotary-piston pumps specially adapted for elastic fluids having the characteristics covered by two or more of groups F04C18/02, F04C18/08, F04C18/22, F04C18/24, F04C18/48, or having the characteristics covered by one of these groups together with some other type of movement between co-operating members having the movement defined in group F04C18/08 or F04C18/22 and relative reciprocation between the co-operating members with vanes reciprocating with respect to the inner member the inner and outer member being in contact along one line or continuous surface substantially parallel to the axis of rotation
• • 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
  • F04C27/008—Sealing arrangements in rotary-piston pumps specially adapted for elastic fluids for other than working fluid, i.e. the sealing arrangements are not between working chambers of the machine
  • F04C27/009—Shaft sealings specially adapted for pumps

Definitions

• the subject of this invention is a displacement pump equipped with a barrier against the fluid leakage, intended to prevent or reduce the fluid exchanges between the inner space of the pump and the outside.
• the fluid leakage between the inner space of the pump and the outside affects negatively in direct manner the pump performance mainly because, with reference to a vacuum pump, it involves a re-entry of air or fluids from the outside towards the inner pump space, thus impairing the depression level attained and the time needed for obtaining the same.
• the fluid leak- age affects negatively the performance even in an indirect manner, because it causes a removal of the oil lubricating the mutually displacing component parts, and in this manner involves an increase of the oil quantity needed for lubricating the pump and therefore an increase of the energy consumed by the device that supplies the lubricating oil, as well as an increases of the strain of the component parts.
• the main object of this invention is to noticeably improve the performance of a displacement pump, particularly but not exclusively a vacuum pump, by reducing the performance loss directly and indirectly caused by the fluid leakages between the pump inner space and the outside.
• Another object of the invention is to attain said object by technically simple means which do not introduce any difficulty in the pump manufacture.
• Still another object of the invention is to attain the desired objects without noticeably increasing the costs of the pump. Therefore, in a motor driven displacement pump, the objects of the invention are attained because a barrier, suitable for preventing or reducing the fluid leakage, is inserted in at least one of the pump areas which are subjected to a fluid leakage between the inner space of the pump and the outside. Said characteristic of the invention can be carried out in different embodiments.
• one of two component parts subjected to relative movement is formed at least one step which determines a limited region of mutual contact between the two component parts subjected to relative movement, thus forming a sort of labyrinth which favores the seal against the fluid leakage.
• said step is provided on the component part that has the higher hardness, whereby during the first periods of operation said step hollows a seat in the component part having the lower hardness, thus providing a particularly effective labyrinth. It is of advantage that to said step is done such a size that, also keeping into account the different thermal expansion coefficients of the component parts, the better operation conditions are attained in the conditions of use in which it is more important that the better seal against the fluid leakage is obtained, said step being in any event sized in such a way that in no operation condition any seize up is generated.
• the radial extension of said step may advantageously be sized by taking into account the lubrication conditions.
• At least one annular seat in one of the two component parts subjected to relative movement is provided at least one annular seat, and in this seat is housed an annular sealing element having a low friction coefficient, kept in sealing contact with both the component parts, also due to the different fluid pressure present in the inner space of the pump and outside.
• annular sealing element on one of the two component parts subjected to relative movement is provided an annular inclined area facing said seat for an annular sealing element, whereby, due to the pressure difference between the inner fluid and the outer fluid, the annular sealing element is biased to contact against the annular inclined area.
• the sealing barrier is provided in the region wherein there is a coupling joint driving the rotor, by forming on the fixed pump portion a step which acts as a closure for the rotor and keeps in position the driving coupling joint, the coupling clearance being an- nulled by the oil penetrating between the parts.
• Figure 1 represents an axial view of a displacement vane pump, deprived of the cover.
• Figure 2 shows on a larger scale a partial section of the pump, taken along a plane which passes through the rotation axis of the rotor and through the contact line between the rotor and the pump body.
• Figure 3 shows a region of the pump which is subjected to a fluid leakage, and to this region are referred the following Figures 4 to 7.
• FIGS 4 to 7 show different embodiments of the sealing against the fluid leakage provided in the pump region of Figure 3.
• Figure 8 shows another embodiment of the sealing against the fluid leakage.
• a displacement vane pump such as a vacuum pump for automotive application, comprises a body 1 delimiting a chamber 3 wherein is housed a rotor 4, which is rotatably mounted in support members 2 of body 1 , and is driven by a motor (not shown) by means of a driving coupling joint 5.
• the rotor is tangent along a line 6 to the pump body 1 , and it carries a vane 7 which, when rotated by the rotor within chamber 3 with its own end portions contacting the wall of body 1 , operates the pumping action in a manner which is well known to those skilled in the art.
• a first embodiment according to the invention involves the provision of at least one step 4.1 protruding in diameter in the guide region.
• the step 4.1 is provided on the less yielding element, that in this case is the rotor 4, but in general it may be the rotor 4 or the support member 2, in accordance with the materials used in the manufac- ture of the component parts.
• the size of the step is chosen in such a way that, in the operating conditions, the coupling is of uncertain type. According to the choice of the materials present in this coupling, different coefficients of thermal expansion may be observed, and therefore, when the coefficient of thermal expansion of the materials is different, the field of the functional clearance varies depending on the operation conditions. For this reason the step should be sized by keeping into account the operation conditions wherein it is more important that the better condition is attained.
• the step should be sized in such a way that in no operation condition any seize up is generated.
• the less yielding component part on which the step is provided hollows a seat in the more yielding component part, thus providing a sort of labyrinth which favors the seal against the fluid leakage.
• the height of the step zone will be sized by taking into account the height of the guide component part and the lubrication conditions. In order to prevent seize up phenomena, it is suitable to provide some holes arranged for directing the lubricant to the region of relative gliding of the component parts.
• a second embodiment of the invention is represented in Figure 5.
• the support member 2 at the motor side there is formed a seat 2.1 , wherein is housed an annular sealing element 8 having a low friction coefficient.
• the diameter of the corresponding region is chosen in such a way as to favor the accommodation of the sealing element 8.
• this solution to a vacuum pump, one should keep into account the fact that the pressure value inside the pump is lower than the outer pres- sure, whereby the annular sealing element 8 is pushed to contact the seat 2.1 at a side of the support member 2 and to contact the rotor 4.
• the third embodiment represented in Figure 6 is a modification of the embodiment of Figure 5.
• a region of light interference is provided between the annular sealing element 8 and rotor 4.
• the fourth embodiment represented in Figure 7 is a modification of the embodiment of Figure 5.
• the annular sealing element 8, which is housed in its seat 2.1 formed in the support member 2 rests at the rotor side against an inclined annular region, which is represented in the section by the inclined line 4.2.
• the component parts remain in mutual contact and, due to the pressure difference between the inner and outer spaces, the annular sealing element 8 is biased to adapt itself to the annular surface represented by the inclined line 4.2.
• the seal against the fluid leakage is obtained by forming a step or flange 2.2 on the support mem- ber 2 of the pump.
• the step 2.2 formed on the support member 2 acts as a closure for rotor 4 and keeps in position the driving joint 5.
• the clearance is annulled by the oil entering between the joint seat at the motor side and the joint itself.
• this invention concerns the provision of a barrier in a displacement pump (and specifically in a vacuum pump) as well as the geometry of this barrier, which can be fixed (if formed by machining or molding) or movable (in the case of the insertion of an annular sealing element) and, when provided in correspondence of the region of possible communication between the inner space of the pump and the outside within the rolling region of rotor, contributes to improve the performances of the pump both in the temperature field in which the pump should operate and outside this temperature field.
• the quantity of oil required for lubricating the pump is reduced, and this allows to dispose of more oil for other motor components or to use a lubri- cation pump of reduced volume.
• the energy absorbed by the lubrication pump is reduced because of its better efficiency and of the reduced oil quantity to be treated by the pump.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Applications Or Details Of Rotary Compressors (AREA)
• Sealing Using Fluids, Sealing Without Contact, And Removal Of Oil (AREA)
• Details And Applications Of Rotary Liquid Pumps (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (2)

Family

ID=40290389

Family Applications (1)

Country Status (4)

Cited By (3)

Family Cites Families (5)

• 2008
  • 2008-01-16 IT ITTO20080033 patent/ITTO20080033A1/it unknown
• 2009
  • 2009-01-12 CN CN200980102475.9A patent/CN101910638B/zh not_active Expired - Fee Related
  • 2009-01-12 EP EP09702342.8A patent/EP2242927B1/en not_active Not-in-force
  • 2009-01-12 WO PCT/EP2009/000244 patent/WO2009090079A2/en not_active Ceased

Non-Patent Citations (1)

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