Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B13/00—Details of servomotor systems ; Valves for servomotor systems
  • F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
  • F15B13/04—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor
  • F15B13/0416—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor with means or adapted for load sensing
  • F15B13/0417—Load sensing elements; Internal fluid connections therefor; Anti-saturation or pressure-compensation valves
  • F15B13/0418—Load sensing elements sliding within a hollow main valve spool
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B13/00—Details of servomotor systems ; Valves for servomotor systems
  • F15B2013/002—Modular valves, i.e. consisting of an assembly of interchangeable components
  • F15B2013/006—Modular components with multiple uses, e.g. kits for either normally-open or normally-closed valves, interchangeable or reprogrammable manifolds

Definitions

• Hydraulic control arrangement for controlling a single-acting hydraulic consumer with regard to direction and speed and directional valve therefor
• the invention is based on a hydraulic control arrangement which is provided for controlling a single-acting hydraulic consumer, in particular a single-acting hydraulic cylinder, with regard to direction and speed and which has the features from the preamble of patent claim 1.
• Such a hydraulic control arrangement is known, for example, from DE 196 31 803 and comprises a directional valve which has a piston bore in a valve housing with a central inlet chamber to which pressure medium can be fed from a pressure medium source, two adjacent consumer chambers and an outlet chamber via which Has pressure medium can be discharged to a tank. There are usually two drainage chambers.
• the directional control valve also has a control piston which can be shifted axially from a central position into a first and an opposite second direction by means of an arbitrarily specified control force and which has first fine control grooves for opening a connection between the inlet chamber and a first of the two consumer chambers in one Shift from the central position in a first direction and with second fine control grooves for opening the connection between the first consumer chamber and the drain chamber is provided in the event of a shift from the central position in the second direction.
• Measuring pistons which can be acted upon by the load pressure cooperate with the control piston in such a way that when the control piston is displaced from the central position, a compensating force which is opposite to the control force and increases with increasing load pressure can be exerted on the control piston.
• the known hydraulic control arrangement is used to control a double-acting hydraulic consumer, for example a differential cylinder, and is a so-called load-sensing control.
• a variable displacement pump or the pressure compensator connected in the bypass to a constant pump is controlled in such a way that a pump pressure is set in a pump line into which the pump is pumping, which is a certain pressure difference, the so-called pump ⁇ p, above the highest load pressure of all hydraulic consumers operated at the same time.
• the pressure medium flows through proportionally adjustable metering orifices formed by control grooves on the control piston to one or the other connection of the hydraulic consumer.
• the two metering orifices of a hydraulic consumer are preceded by a so-called individual pressure compensator, the control piston of which in the closing direction depends on the pressure in front of the metering orifices and in the opening direction is acted upon by the load pressure of the respective hydraulic consumer and by a control spring.
• the pressure compensator maintains a pressure difference across the currently active metering orifice that corresponds to the pressure equivalent of the control spring.
• the invention is based on the object of further developing a hydraulic control arrangement with the features from the preamble of patent claim 1 such that even with a single-acting hydraulic consumer, in particular with a single-acting hydraulic cylinder, with a predetermined control force acting on the control piston with simple A strong increase in the lowering speed of the hydraulic consumer with increasing load pressure is avoided.
• the measuring piston in the hydraulic control arrangement with the features from the preamble of claim 1, can be acted upon by the pressure prevailing in the first consumer chamber when the control piston is displaced in the second direction.
• the measuring piston which is acted upon by the load pressure in the second consumer chamber when the directional valve is used for the actuation of a double-acting hydraulic consumer, is connected to the first consumer chamber when it is lowered and is thus acted upon by the load pressure when it is lowered.
• the compensation force generated thereby increases with increasing load pressure and displaces the control piston in the sense of a reduction in the flow cross section from the first consumer chamber to the outlet chamber.
• control piston has an axial bore which serves to report the load pressure of the hydraulic consumer, which bores when the control piston is displaced in the first direction via a first transverse bore to the first consumer chamber and when the control piston is displaced in the second direction is opened to the second consumer chamber via a second transverse bore.
• the control piston is displaced in the first direction, the pressure from the axial bore is fed into a load reporting chamber via a third transverse bore.
• the measuring piston is guided in the control piston and exposed to the pressure in the axial bore in the interior of the control piston and can be supported on the outside against a stop of the valve housing.
• the invention is also embodied in a directional valve according to claim 9, which has the directional valve-specific features from claims 1 to 3 and which can be advantageously configured according to claims 4 to 8.
• FIG. 1 shows the hydraulic control arrangement including the directional control valve as a circuit diagram
• Figure 2 shows a longitudinal section through the directional control valve with the control piston in the
• Middle position and Figure 3 shows a longitudinal section through the directional control valve with the control piston after a shift in the sense of a discharge of pressure medium from the hydraulic consumer.
• FIG. 1 several hydraulic consumers can be supplied with pressure medium, usually mineral oil, from a variable displacement pump 10 via a directional valve block 11.
• the circuit diagram explicitly shows only a single-acting hydraulic cylinder 12 and a directional valve disk 13 with which the pressure medium paths between the hydraulic cylinder, the variable displacement pump and a tank 14 can be controlled.
• the variable displacement pump is controlled by current demand and has a load-sensing controller 15, to which the highest load pressure of all simultaneously actuated hydraulic consumers is reported via a connection LS of an input element 16 of the directional valve blocks 11.
• the variable pump sucks pressure medium from the tank 14 and emits it into a pressure line 17 leading to a pump connection P of the input element. It promotes so much pressure medium in each case that a pump pressure above the highest load pressure is generated in the pressure line 17 by the pump ⁇ p, which is usually set to a value between ten and twenty bar.
• the directional control valve disk 13 comprises a proportionally adjustable directional control valve 20 and a pressure compensator 22 connected upstream of a metering orifice 21 of the directional control valve and connected to the pump connection P at its input.
• the hydraulic cylinder for extending the piston rod can be actuated independently of the load pressure.
• a piston bore 31 passes through a valve housing 30, in which a control piston 32 is axially movable.
• the length of the control piston 32 corresponds to the length of the piston bore 31 from one end face 33 to the other end face 34 of the valve housing 30.
• the piston bore 31 is surrounded by five axially spaced control chambers.
• the fluidic connections under the three control chambers are controlled by the control piston 32.
• the central control chamber 35 of the five control chambers is the inlet chamber.
• the pressure medium flows in via a channel 36 from the pressure compensator 22, which is also shown only schematically in FIG.
• the two consumer channels 40 and 41 run essentially parallel to one another and perpendicular to the piston bore 31.
• Each consumer chamber 38 and 39 is followed by an outlet chamber 44 and 45, which is open to one of two tank channels 46 passing through the valve housing 30.
• the control piston 32 assumes a central position due to two centering springs 47, which are accommodated in covers 48 fastened to the end faces 33 and 34 of the valve housing 30 and closing the piston bore 31 to the outside, from which it moves in a first direction and one to it opposite second direction can be adjusted continuously. At maximum stroke, it strikes an adjustable stroke limiter 49.
• the control piston 32 has a piston neck 57 which is centered in the central position to the inlet chamber 35.
• the two piston collars 58 and 59 on both sides of the piston neck 57 are so long that in the central position of the control piston there is one end face at a distance from the inlet chamber 35 and the other end face in the outlet chamber 44 and 45, respectively.
• the piston collar 58 has control grooves 60 which are axially open on the end face facing the inlet chamber 35 and control grooves 61 which are axially open on the end face facing the outlet chamber 44.
• the control grooves 60 and 61 are covered by the housing web located between the control chambers 35 and 44, so that there is no open fluidic connection between the individual control chambers via the control grooves.
• the piston collar 59 has no control grooves and separates the consumer chamber 39 from the inlet chamber 35 and the outlet chamber 45 in every position of the control piston. After a short further neck, the piston collar 59 is followed by a further piston collar which defines the spring chamber in the one cover 48 seals against the drain chamber 45.
• the distance between the drain chamber 44 and the end face 33 of the valve housing 30 is greater than the distance between the drain chamber 45 and the end face 34.
• the chamber 65 is without any function in the present case.
• a piston section 67 extends from the end face 33 of the valve housing 30 into the area of the housing between the chamber 63 and the drain chamber 44.
• a flat annular groove 69 is screwed into this piston section, via which the load-sensing chamber 64 is connected to the chamber 63 in the central position of the control piston 32 shown.
• the piston section 67 has an indentation 70 on an outer edge of a piston collar 71 facing the discharge chamber 44, which is located between the annular groove 69 and a piston neck in the region of the discharge chamber 44, and the effective width of the piston collar 71 is smaller than the width of the chamber 63 makes and through which the chamber 63 and the drain chamber 44 are open to each other with a small opening cross-section when the control piston 32 is in its central position. Only after a certain path of the control piston from its central position in the second direction is this fluidic connection between the drain chamber 44 and the chamber 63 and thus the chamber 64 closed.
• control piston 32 extends through an axial bore 74, which is crossed by two transverse bores 75 and 76, of which the transverse bore 75 in the piston collar 58 and the transverse bore 76 in the piston collar 59 of the control piston 32 are each in such a position that they in the center position of the control piston is covered by the wall of the piston bore 31.
• the transverse bore 75 becomes the consumer chamber 38 and when the movement of the control piston in the second direction, the transverse bore 76 to the consumer chamber 39 out.
• the axial bore to the annular groove 69 is open via a further transverse bore 77, which is introduced into the control piston 32 in the region of the annular groove 69 up to the axial bore 75.
• the pressure compensator 22 has a control piston 23, which is inserted in a manner not shown in a blind bore which runs parallel to the piston bore 31 and is introduced into the valve housing 30 from the end face 34.
• the outlet of the pressure compensator is connected to the inlet chamber 35 of the piston bore 31 via the channel 36.
• the control piston 23 is acted upon in the sense of an increase in the flow cross section of the pressure compensator by the pressure prevailing in the load reporting chamber 64, which is equal to the load pressure of the hydraulic cylinder 12 when the control piston is displaced in the first direction, and by a compression spring 78, the pressure equivalent of which is in the range is between 10 and 20 bar.
• the pressure in the inlet chamber 35 of the piston bore 31 is applied to the control piston.
• the axial bore 74 is widened in one step toward both ends of the control piston 32.
• a bushing 79 or 80 is screwed into the respective extension, in which a measuring piston 81 or 82 is movably guided in the axis of the control piston.
• the guide diameter of the volumetric pistons is approximately one seventh of the diameter of the control piston, which determines the area on which a control pressure acts on the control piston. With its outer end, the volumetric pistons can be supported on the stroke limiters 49.
• each measuring piston 80 has a head through which it is held captively in the screwed-in bushing and which holds the measuring piston in the central position of the control piston and when it moves in one direction at a distance from the respective stroke limiter holds.
• control grooves 60 and 61 on the piston collar 58 are covered in the central position of the control piston 32, so that no fluidic about them There is a connection between the control chambers. If the control piston 32 is displaced far enough from its central position in the first direction by acting on the spring chamber in a cover 48 with a control pressure, the transverse bore 75 to the consumer chamber 38 is first opened after a short initial stroke and then a flow cross-section via the control grooves 60 on the piston collar 58 opened between the inlet chamber 35 and the consumer chamber 38, the flow cross section increasing with increasing stroke of the control piston. Pressure medium flows to the hydraulic cylinder 12 via the consumer channel 40 and the connection 42 of the valve housing 30.
• the load pressure of the hydraulic cylinder 12 is applied via the transverse bore 75, via the axial bore 74 and via the transverse bore 77 in the load-reporting chamber 64 and thus on one side of the pressure compensator 22 and, if it is the highest load pressure, is also via a from FIG apparent shuttle valve 83 reported to the pump controller 15. Due to the flow cross section at the control grooves 60 of the piston collar 58, the metering orifice 21 from FIG. 1 is realized, via which a pressure difference drops, which is kept constant by the pressure compensator 22 and which corresponds to the pressure equivalent of the compression spring 78. The amount of pressure medium flowing to the hydraulic consumer is thus only determined by the flow cross section of the metering orifice.
• this flow cross-section for the pressure medium flowing to the hydraulic consumer is also influenced by the load pressure of the hydraulic consumer.
• the load pressure acts on the two measuring pistons 81 and 82, of which the measuring piston 81 is supported on the corresponding stroke limiter 49 after a displacement of the control piston 32 in the first direction over an initial stroke, while the measuring piston 82 has its head on the bushing 79 is applied.
• the load pressure therefore generates on the control piston 32 a force directed in the second direction and thus against the control force generated by the control pressure.
• the area on which the control pressure acts is about forty times as large as the area on which the load pressure acts.
• a spring chamber in one of the two covers 48 is acted upon by a control pressure.
• two electromagnetically actuated pilot valves 84 and 85 are used, which are seated on the valve disk 13 in a manner not shown in detail and which are designed as proportionally adjustable pressure reducing valves.
• the two pilot valves 84 and 85 are supplied with control oil via a channel 86 in the valve disk 13, while control oil can flow out via a channel 87.
• the control piston 32 is adjusted in the second direction by pressurization on its other end face, thereby opening a flow cross-section between the consumer chamber 38 and the discharge chamber 44 via the control grooves 61 on the piston collar 58. If a specific control pressure is applied to the control piston, the lowering speed of the hydraulic consumer should increase less with increasing load pressure than would be the case with a constant flow cross section due to the increase in pressure difference across the flow cross section.
• the two consumer channels 40 and 41 and thus the two consumer chambers 38 and 39 are fluidly connected to one another via a bore 90 which runs parallel to the valve bore 31 and which can be introduced into the valve housing 30 through a stepped bore 91, which serves to receive a secondary pressure limiting and replenishment valve 92 arranged between the consumer channel 40 and a tank channel 46 or, because the hydraulic consumer is single-acting, is closed by a plug 93. Since only control oil flows through the connection hole 90, its diameter can be small. As such, the fluid path for connecting the consumer chamber 39 to the pressure medium can be telweg between the consumer chamber 38 and the hydraulic consumer are also outside the valve housing 30 and lead via the connection 43. However, the connection within the valve housing appears much easier. The connection 43 is then closed by a plug 94.
• the transverse bore 76 to the consumer chamber 39 is opened after a short initial stroke, in which the load pressure of the hydraulic cylinder 12 is present because of the connecting bore 91.
• the load pressure then also acts in the axial bore 74 and acts on the two measuring pistons 81 and 82, of which the measuring piston 82 is supported on the stroke limiter 49 and the measuring piston 81 with its head on the control piston 32.
• the load pressure thus generates a compensation force on the control piston which is opposite to the control force. Only when the control force exceeds the sum of the compensation force and the spring force does the control piston move beyond the initial stroke. Only now, i.e.
• the control grooves 61 open a flow cross-section between the two control chambers 38 and 44.
• the control piston assumes a position in which between the control force on the one hand and the sum of the compensation force and the force of the one Centering spring 47 there is a balance.
• the control piston is displaced less far from the central position than in the case of a valve without compensating force, in which the control piston assumes a position at a predetermined control pressure in which the control force is equal to the spring force. Accordingly, the flow cross-section between the consumer chamber 38 and the outlet chamber 44 via the control grooves 61 is smaller.
• control grooves By appropriate shaping of the control grooves, it can be achieved that, with a given control pressure and increasing load pressure, the increase in the pressure difference across the flow cross section is largely compensated for by a reduction in the flow cross section.
• the provision of one or more measuring pistons is in principle also possible with direct actuation by means of proportional magnets.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Fluid-Pressure Circuits (AREA)
• Multiple-Way Valves (AREA)
• Mechanically-Actuated Valves (AREA)
• Non-Deflectable Wheels, Steering Of Trailers, Or Other Steering (AREA)
• Servomotors (AREA)

Applications Claiming Priority (3)

Publications (2)

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• 2001
  • 2001-05-05 DE DE10121924A patent/DE10121924A1/de not_active Withdrawn
• 2002
  • 2002-04-11 DK DK02742885T patent/DK1386084T3/da active
  • 2002-04-11 EP EP02742885A patent/EP1386084B1/fr not_active Expired - Lifetime
  • 2002-04-11 WO PCT/EP2002/004022 patent/WO2002090778A2/fr not_active Ceased
  • 2002-04-11 DE DE50205586T patent/DE50205586D1/de not_active Expired - Lifetime
  • 2002-04-11 AT AT02742885T patent/ATE315728T1/de active

Non-Patent Citations (1)

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