EP0064332A1 - Hydraulikventil und hydraulischer Steuerkreis - Google Patents

Hydraulikventil und hydraulischer Steuerkreis Download PDF

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Publication number
EP0064332A1
EP0064332A1 EP82301800A EP82301800A EP0064332A1 EP 0064332 A1 EP0064332 A1 EP 0064332A1 EP 82301800 A EP82301800 A EP 82301800A EP 82301800 A EP82301800 A EP 82301800A EP 0064332 A1 EP0064332 A1 EP 0064332A1
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EP
European Patent Office
Prior art keywords
fluid
spool
valve
pressure
inlet
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP82301800A
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English (en)
French (fr)
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EP0064332B1 (de
Inventor
John Sidney Humphries
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
JC Bamford Excavators Ltd
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JC Bamford Excavators Ltd
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Filing date
Publication date
Application filed by JC Bamford Excavators Ltd filed Critical JC Bamford Excavators Ltd
Publication of EP0064332A1 publication Critical patent/EP0064332A1/de
Application granted granted Critical
Publication of EP0064332B1 publication Critical patent/EP0064332B1/de
Expired legal-status Critical Current

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    • 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

Definitions

  • This invention relates to a fluid control valve and a fluid control system for use in controlling a fluid operated apparatus such as a hydraulic prime mover such as a double acting hydraulic ram.
  • fluid is pumped to an inlet of a control valve which controls the flow of fluid to one or more load outlets which is or are connected with the fluid operated apparatus.
  • the control valve controls the speed and direction of movement of the fluid operated apparatus and it is usual to provide a control member such as a spool, which may be manually moved by a control lever, movement of the spool permitting the fluid to flow from the inlet either to the load outlet or to a drain outlet. Increased movement of the spool increases the flow rate through the valve to the load outlet.
  • An object of the present invention is to provide a new and improved fluid control valve and a new and improved fluid control system for use in controlling a fluid operated apparatus.
  • a fluid control valve having an inlet, at least one load outlet adapted to be operatively connected to a fluid operated apparatus, a fluid flow path through the valve from the inlet to the or each load outlet, at least one control member to control the flow of fluid through the valve, and the at least one control member being selectively movable from a neutral position, wherein fluid is prevented from flowing from the inlet to the or any load outlet, to an operative position, wherein fluid is permitted to flow from the inlet to a selected load outlet, and an operating member movable in response to the position of the or each control member to control the fluid flow from the inlet to the or each selected load outlet.
  • a control valve in accordance with the present invention has the following advantages.
  • an improved control characteristic is obtained compared with known valves, that is to say, a predetermined flow rate is achieved at the or each selected load outlet for a predetermined movement of the control member, irrespective of the magnitude of the load and hence of the pressure at the load outlet.
  • compensated valves Some known valves, referred to as compensated valves, have a compensating spool to direct the fluid to a drain outlet of the valve or to a selected load outlet or outlets, in a proportion depending upon the load pressure; whereby the compensating spool adopts an equilibrium position with the load pressure and the fluid pressure at the inlet, acting oppositely on the compensating spool, usually the fluid pressure at the inlet being maintained slightly higher than the load pressure.
  • load pressure we mean the total pressure at the or each of the load outlets of the valve, imposed by the load or loads on the fluid system.
  • a valve in accordance with the invention may have such a compensating spool.
  • the position of the main spool determines the difference between the inlet pressure and the load pressure which act in opposition on the compensating spool, hence movement of the main spool which increases the flow to the selected load outlet causes a reduction in said pressure difference so the compensating spool moves in the direction to reduce flow of fluid to the drain outlet thus providing more fluid for feeding to the load outlet.
  • the flow rate of fluid to a load outlet is controlled independently of the load pressure.
  • a spring means may be provided to urge the compensating spool with the load pressure in a direction so that that inlet pressure is maintained slightly higher than the load outlet pressure.
  • the means to direct fluid at the load pressure to act on the compensating spool has comprised a separate sensing passage extending from the or each load outlet and communicating via a series of shuttle valves with the compensating spool.
  • the operating member When the invention is applied to a compensated valve, instead of requiring the provision of the plurality of sensing passages and shuttle valves, the operating member provides a restriction in the flow path between the inlet and a gallery common to all load outlets to permit of a pressure difference between the gallery and the inlet so that the pressure in the gallery can equal the load pressure, the fluid pressure in said gallery acting on the compensating spool.
  • the invention may be applied to a valve wherein fluid is supplied to the valve by a variable displacement pump, the pump rate of the variable displacement pump being automatically adjustable in response to a signal, derived from the position of the operating member, which is dependent on the selected position of the control member.
  • the position of the operating member determines the signal sent to a means, to change the output of the pump. In this way the flow rate of fluid to a load outlet is controlled independently of the load pressure.
  • a compensating spool such as that described above may be also provided.
  • fluid directed to the drain outlet of the valve is returned to a reservoir from where it is recirculated.
  • fluid directed to the drain outlet of the valve is returned to a reservoir from where it is recirculated.
  • the operating member may comprise a main spool, a main spool chamber receiving one end of the main spool therein, the position of the main spool, being controlled by the pressure of fluid within the main spool chamber which acts on the main spool, fluid being fed to said main spool chamber from the fluid flow path of the valve, the pressure of fluid in the main spool chamber being dependent upon the selected position of the control member.
  • Resilient means may be provided to bias the main spool into a neutral position wherein fluid is prevented from flowing through the valve to a load outlet when the pressure of fluid in the main spool chamber is insufficient to move the main spool into an open position.
  • a regulating spool may be provided to regulate the flow of fluid from the fluid flow path to said first chamber, the regulating spool having a portion in sealing sliding engagement with a regulating spool chamber of the valve into which it is urged by a spring means, means being provided to direct fluid from the flow path of the valve into the regulating spool chamber which communicates with said main spool chamber, to urge the regulating spool against the force of the spring means outwardly of the regulating spool chamber, said fluid directing means including a duct which, as the regulating spool moves outwardly of the regulating spool chamber in response to a sudden increase in load pressure, becomes increasingly blocked thereby reducing the flow of fluid to said main spool chamber and thereby preventing the sudden increase in pressure acting on the operating member.
  • the pressure of fluid in the main spool chamber is maintained constant or substantially constant depending on the selected position of the control member, irrespective of any fluctuation in the pressure of fluid in the fluid flow path.
  • the regulating spool chamber may comprise a bore in the main spool, the main spool having a duct which, as the regulating spool is urged outwardly of the regulating spool chamber, becomes increasingly misaligned with the duct of the fluid directing means.
  • the control member may comprise a further spool, the fluid in the main spool chamber which acts on the main spool being in communication with the further spool so that when the control member is placed in said neutral position, the fluid in the main spool chamber is not pressurised to urge the main spool from said neutral position, and when the control member is placed in a selected operative position, the fluid in the main spool chamber is pressurised to urge the main spool to an open position depending on the selected position of the control member wherein fluid is permitted to pass through the valve from the inlet to a selected load outlet.
  • the control member may be received within a passageway within the control valve and be movable from the neutral position into one of a range of operative positions whereby the fluid may be directed to a selected one or a selected plurality of load outlets.
  • the fluid flow to the load outlet or outlets may be also controlled by the control member although it will be understood that the amount of fluid which flows through the valve is primarily dependent on the position of the operating member.
  • the fluid operated apparatus comprises a double acting hydraulic ram
  • one load outlet may be operatively connected to the apparatus to extend the ram
  • another load outlet may be operatively connected to the apparatus to retract the ram.
  • control member may be provided within the valve, each control member having an associated load outlet or outlets operatively connected to a fluid operated apparatus, whereby the control valve may be utilised to operate more than one fluid operated apparatus.
  • control valve may be utilised to operate more than one fluid operated apparatus.
  • only one operating member need be provided.
  • the signal from the control valve may be derived from within the main spool chamber of the control valve in which the pressure of fluid is dependent upon the position of the control member.
  • a fluid control system comprising a fluid operated apparatus, variable output pump means to pump fluid to the apparatus via a control valve having a fluid inlet and a fluid outlet, the fluid outlet being operatively connected to the fluid operated apparatus, the output of the variable output pump being adjustable in response to a signal provided from the control valve which indicates the fluid requirements of the fluid operated apparatus.
  • the control valve may comprise a valve according to the first aspect of the invention and, in this case, the signal provided from the control valve may be derived from the main spool chamber of the valve.
  • a third aspect of the invention we provide a method of operating a fluid operated apparatus comprising the steps of pumping fluid with a variable output pump to a fluid inlet of a control valve, the control valve comprising a fluid outlet operatively connected to the fluid operated apparatus, and varying the pump rate in response to a signal from the control valve which indicates the fluid requirements of the fluid operated apparatus.
  • a fluid control valve 10 for use in a hydraulic system.
  • the valve 10 has a fluid inlet 11 to which fluid is supplied from a fluid reservoir under pressure, by a fixed output pump, two load outlets 12 and 13 either of which may have fluid directed thereto, through the valve 10, from the inlet 11, and a drain outlet 14 which communicates with the fluid reservoir to which fluid may be returned.
  • the control valve 10 may control a fluid operated apparatus comprising a double acting hydraulic ram or a group of such rams, wherein fluid is supplied to the ram or rams from an outlet 12 for example of the control valve 10, to extend the ram or rams, and from the other outlet 13 to retract the rams.
  • fluid from the ram passes back to outlet 13, which acts as a return inlet, from where the fluid is directed to the drain outlet 14 and hence returned to the fluid reservoir, as hereinafter described.
  • outlet 13 acts as a return inlet
  • the fluid passes back to outlet 12 which acts as a return inlet, and from where the fluid is directed to the drain outlet 14 and hence returned to the fluid reservoir.
  • the control valve 10 further comprises a common feed gallery 15 into which fluid is permitted to pass from the inlet 11 through a throat T formed between a shoulder 19a of a land 19 of an operating member comprising a main spool 18, when the main spool 18, which is slidable in a passage l8a in the valve 10, is urged into an operating position as shown in Figure 1 against the force of a coil compression spring 17, which urges the spool 18 to the right as seen in Figure 1.
  • the throat T provides a restriction in the flow path from the inlet to the feed gallery 15 so that there can exist a pressure difference between the inlet 11 and the feed gallery 15.
  • the shoulder 19a and throat T are of such configuration that the magnitude of the restriction varies smoothly with the position of the spool 18, reducing as the spool 18 moves to the left.
  • fluid may pass from the inlet 11 to the feed gallery 15 and hence into a chamber 15a ( Figure 2) which communicates via a non-return valve 20, with a distribution passageway 22 from where the fluid may pass to a selected one of the outlets 12, 13, depending upon the position of a control member comprising a control spool 24 which is slidable in a control spool chamber 24a ( Figures 2 and 3) of the valve 10.
  • the non-return valve 20 has a shoulder 20a on which the pressure of fluid in chamber 15a acts, the shoulder 20a being of greater area than the sealing area 20b thereof and thus as the pressure in the distribution passageway 22 increases as the pressure at a selected load outlet 12, 13, increases, the valve 20 is opened so that fluid flows from the chamber 15a via the valve 20 into passageway 22 and hence to outlet 12 or 13. The load pressure at the selected outlet 12 or 13 is thus transmitted, when the valve 20 is open, to the feed gallery 15.
  • Figure 3 shows the control spool 24 in a right operative position, in which position fluid is allowed to pass from the distribution passageway 22 to the outlet 12 via a main land 26 provided on the control spool 24 to extend the ram or rams. Fluid which is passed back from the ram or rams to outlet 13, which acts as a return inlet, passes via a further land 27 into a tank galley 59. When the control spool 24 is in an opposite left operative position, fluid is allowed to pass from the distribution passageway 22 to the outlet 13 via the further main land 27 in the control spool 24, to retract the ram or rams. Fluid which is passed back from the ram or rams to outlet 12, which acts as a return inlet, passes via land 26 into a second tank galley 63.
  • Figure 2 shows the control spool 24 in a neutral position wherein fluid is prevented from passing from the distribution passageway 22 to either of the outlets 12 and 13.
  • the position of the control spool 24 is manually controlled in the valve 10 shown, by a manually operable control mechanism 28 which comprises an operator controlled lever 30 pivotable about pivot axis 31, the lower end 32 of the lever being pivotally received in a recess 33 of the control spool 24 so that as the lever 30 is rotated clockwise as seen in the drawings about pivot axis 31, the control spool 24 is moved to the left, and conversely as the control lever 30 is moved anticlockwise, the control spool 24 is moved to the right.
  • a manually operable control mechanism 28 which comprises an operator controlled lever 30 pivotable about pivot axis 31, the lower end 32 of the lever being pivotally received in a recess 33 of the control spool 24 so that as the lever 30 is rotated clockwise as seen in the drawings about pivot axis 31, the control spool 24 is moved to the left, and conversely as the control lever 30 is moved anticlockwise, the control spool 24 is moved to the right.
  • control lever 30 When the control lever 30 is upright, the control spool 24 is in the neutral position, as shown.
  • a spring biased compensating spool 35 is provided whereby the proportion of fluid from the inlet 11 directed to a selected load outlet 12, 13, and/or to main drain outlet 14 is metered thereby ensuring a controlled flow of fluid at the load outlet 12 or 13 as required, thereby improving the control characteristic of the valve 10.
  • the spool 35 is slidable in a compensating spool chamber 47a.
  • the spool 35 has a land 35a and, depending on the position of the spool 35 in the chamber 47a, fluid may pass from the inlet 11 via lower part llb thereof, through a passage 60 past land 35a, to the tank gallery 59 and hence to the main drain outlet 14 via a communicating ducts, which cannot be seen in the drawings.
  • the right-hand end 38 of the spool 35 is slidably received in an end chamber 47 of chamber 47a.
  • the spool 35 has an aperture 36 therein through which a proportion of the fluid from the lower part 11b of the inlet 11 passes and hence passes into a central passage 37 within the spool 35. This fluid acts on the end 38 of spool 35 to urge the spool 35 to the left, outwardly of the chamber 47.
  • a proportion of fluid from feed gallery 15 (the pressure of which is dependent upon the pressure at a selected load outlet 12 or 13 passes through an aperture 60a smaller than aperture 36, in the lefthand end 39 of the spool 35 and, along with a coil spring 40, provided at the end 39 of the spool 35, counteracts the fluid pressure at the right end 38 of the spool 35.
  • the land 35a of the spool 35 will permit an increasing amount of fluid to pass from the lower end 11JD of the inlet 11, via the duct 60 into tank gallery 59 and hence to the main drain outlet 14, and thus the pressure of fluid at the inlet 11 will be caused to decrease as the resistance to the flow of fluid to the drain outlet is low.
  • the inlet pressure will be maintained slightly greater than the load pressure, due to the action of spring 40.
  • the spool 35 will achieve an equilibrium position balanced between the pressure of fluid at the inlet 11 which acts on the end 38 of the spool 35 and the load pressure which is transmitted via gallery 15 to the end 39, along with the force of the spring 40.
  • the quantity of fluid which escapes to the tank gallery 59 is therefore metered by the spool 35 depending on the load pressure, and the inlet pressure is always maintained slightly greater than the load pressure in the gallery 15.
  • the throat T described hereinbefore permits of the existence of a pressure difference between the inlet 11 and the feed gallery 15, which pressure difference is maintained by the above described variation in the proportion of fluid which passes from the inlet 11 to the tank gallery 59.
  • this can be achieved by altering the strength of the spring 40 and the relative areas of the spool 35 acted upon by the inlet and outlet pressures accordingly.
  • the throat T would again permit of the existence of a pressure difference, this would be prevented.
  • a pressure release valve 62 is provided to limit the fluid pressure in the region 61 of the chamber 47a at the end 39 of the spool 35.
  • Fluid which escapes via the pressure release valve 62 passes into the second tank gallery 63 which also communicates with the main drain outlet 14 by a communication duct which cannot be seen in the drawings.
  • the size of the duct 60a is very small compared with the size of the aperture 62a of the release valve 62, so that if the pressure in the region 61 of the chamber 47a increases above a predetermined value, due for example to an increase in the load pressure when the valve is actuated, the release valve 62 will be opened and the pressure of fluid in the region 61 will thus be maintained below the predetermined value. The maximum load exerted on the fluid controlled apparatus will thus be restricted.
  • the outlets 12, 13 are also each provided with pressure release valves 64, 65 so that over pressurisation at the outlets 12, 13 cannot take place.
  • a regulating spool 41 having radial apertures 42 and a central passage 43 is slidable in a passage 41a in an axial bore of the main spool 18 to maintain the pressure in a main spool chamber 52 in which the right hand end of main spool 18 is received, substantially constant irrespective of the load pressure which is transmitted to the inlet 11 by throat T.
  • a proportion of the fluid from the inlet 11 passes into apertures 48 in the main spool 18 and through the aligned radial apertures 42 of the regulating spool 41 into the central passage 43 within the spool 41, from where some fluid escapes by a narrow jet 75 to the main spool chamber 52.
  • the chamber 52 communicates with a metering orifice 53 ( Figure 3) adjacent the control spool 24 to which fluid is directed from the chamber 52.
  • control spool 24 When the control spool 24 is in the neutral position (i.e. Figure 2 position), the orifice 53 is aligned with graduated lands 54 of the control spool 24 which allows fluid to pass from chamber 52 through orifice 52, and escape via a communicating duct (not shown) to the main drain outlet 14.
  • the main spool 18 When the metering orifice 53 is open, i.e. aligned with the associated lands 54, the main spool 18 is held in the above mentioned right position by the coil spring 17 which acts on the rear end thereof, because the pressure in the chamber 52 is insufficient to lift the main spool 18 from the chamber 52 against the force of the spring 17. Thus, the entry of fluid from the inlet into the feed gallery 15 and hence to a load outlet 12, 13 is blocked and no fluid can enter the gallery 15 from the inlet 11 as throat T is closed. Thus the compensating spool 35 will be urged by the inlet pressure, to its fully left hand position as the pressure in region 61 of chamber 47a will be overcome, so that all the fluid fed to the inlet 11 will be directed to the main drain outlet 14.
  • control spool 24 When the control spool 24 is moved into either to the right or left operative positions, for example the right operative position shown in Figure 3, escape of fluid via the associated land 54 is restricted which results in a pressure build-up in chamber 52.
  • the main spool 18 will be moved against the force of the spring 17 to the operative position hereinbefore described, to permit fluid to pass from the inlet 11 into feed gallery 15 and hence to the associated outlet 12 or 13 depending on the control spool 24 position.
  • the restriction provided by the throat T will be reduced so that the pressure difference between the feed gallery 15 and the inlet 11 will tend to fall, and as a result, the compensating spool 35 will move to the right, allowing a greater proportion of fluid to become available to flow into the gallery 15 and hence be directed to the selected load outlet 12 or 13. In this way, the flow rate of fluid from the inlet to a selected load outlet is controlled.
  • a drain outlet P is provided in the rear left end of spool 18, to allow any fluid trapped at the rear end 46 of the regulating spool 18 to escape, as the spool 18 moves to the left. This outlet P is blocked when the spool 18 is in a right position where the throat T is closed, so that the fluid cannot pass from the rear end 46 of spool 18, to the drain outlet 14.
  • the lands 54 of the control spool 24 are graduated so that escape of fluid and pressure build-up in the chamber 52, and hence the extent of movement of the main spool 18 are directly dependent upon the extent to which the control lever 30 is moved.
  • the main spool 18 may move to the left to such an extent that the tank gallery 59 will communicate with the chamber 52 and thus the pressure build-up in chamber 52 will be limited and further movement of the main spool 18 prevented.
  • the spool 41 is arranged to be urged to the left as load pressure increases, by fluid acting on the right end 44 thereof in a regulating spool chamber 49, against the resilient force of a spring 45 which acts at the other end 46 of the spool 41.
  • the spool 41 will be moved to the left to such a degree that the apertures 42, 48 will become increasingly misaligned, and thus provide an increasingly blocked duct so that the fluid supply to the central passage 43 of the spool 41 will, at a threshold be completely cut off, until the pressure of fluid in the chamber 49 decreases below the threshold, as fluid escapes via jet 75.
  • spool 18 does not respond to sudden fluctuations and hence an easily controlled substantially constant pressure and flow rate fluctuation-free fluid supply will thus be obtained at a selected load outlet 12, 13, the flow rate depending on the position of the control lever 30, more fluid being provided at the outlet 12, 13 and the fluid permitted to escape via passageway 60 to the tank gallery 59 being reduced as the control lever 30 is moved from its neutral position.
  • control valve 10 In the control valve 10 described, only a small manual effort is necessary to operate the control lever 30 compared with known valves as the high fluid pressures do not act on the control spool 24 but are transmitted to the main spool 18.
  • the control characteristic of the valve 10 is considerably improved compared to known valves, and as the effort needed to operate the control lever 30 is small, an operator has a fine control of the fluid operated apparatus, increased movement of the lever 30 resulting in a steady increase in speed of the fluid operated apparatus regardless of fluctuations in load pressure.
  • a further advantage of the valve described is that there are few pressure losses within the valve, and little wasted effort on the pump due to fluid friction and other parasitic losses which normally occur in fluid control valves.
  • each pair of load outlets having an associated control spool, so that more than one hydraulic ram or set of hydraulic rams can be controlled using only the one control valve.
  • the spools 24 may be controllable each independently by separate control levers 28 or a group of the spools may be controlled by a common lever 28. In this case fluid is supplied to each control spool from the common feed gallery 15. Hence the load pressure obtained in the feed gallery 15 will be the resultant of all the individual load pressures.
  • the further control spools 24 will each have further metering orifices 53 with lands 54 and will extend parallel to the control spool 24 shown.
  • valve 10 may be modified and utilised with a variable displacement pump.
  • the pump rate is decreased to a minimum resulting in a saving of the fuel necessary to operate the pump.
  • Such a fluid control system is shown diagrammatically in Figure 4.
  • the control valve 10 is provided at the inlet 11 with fluid from a reservoir 101 via a variable displacement pump 102, the pump rate of which is controlled by the fluid pressure in a servo pipe 104 which is connected to the connecting passage C of the chamber 52 of the valve 10 which is indicated in chain dotted lines on Figure 1.
  • An outlet such as outlet 12 from the valve 10 feeds hydraulic fluid to a fluid operated apparatus such as a hydraulic ram 110 so as to extend the ram 10, fluid from the ram 110 passing back through to outlet 13 of the valve 10 which acts as a return inlet, to drain outlet 14 to the reservoir 101 via a filter 112.
  • a fluid operated apparatus such as a hydraulic ram 110
  • the pump rate of the variable displacement pump 102 increases and vice versa.
  • the compensating spool 35 may be retained when the valve is utilised with a variable displacement pump.

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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)
  • Sliding Valves (AREA)
EP19820301800 1981-04-03 1982-04-05 Hydraulikventil und hydraulischer Steuerkreis Expired EP0064332B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8110465 1981-04-03
GB8110465 1981-04-03

Publications (2)

Publication Number Publication Date
EP0064332A1 true EP0064332A1 (de) 1982-11-10
EP0064332B1 EP0064332B1 (de) 1985-07-24

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ID=10520889

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19820301800 Expired EP0064332B1 (de) 1981-04-03 1982-04-05 Hydraulikventil und hydraulischer Steuerkreis

Country Status (4)

Country Link
EP (1) EP0064332B1 (de)
JP (1) JPS57184707A (de)
CA (1) CA1179916A (de)
DE (1) DE3264859D1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0170815A1 (de) * 1984-07-10 1986-02-12 Robert Bosch Gmbh Hydraulische Steuereinrichtung

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA2450994C (en) 2003-11-27 2010-08-10 Precision Drilling Technology Services Group Inc. Method and apparatus to control the rate of flow of a fluid through a conduit

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2503870A (en) * 1946-05-03 1950-04-11 Vickers Inc Flow regulating device
DE908541C (de) * 1940-06-15 1954-04-08 Askania Werke Ag Selbsttaetiger Regler mit Kraftschalter
GB944167A (en) * 1959-03-03 1963-12-11 Heinz Teves Improvements in or relating to hydraulic circuits
DE1911131A1 (de) * 1969-03-05 1970-09-17 Buchholz Helmut Hydraulische Steuereinrichtung
DE2038813A1 (de) * 1970-08-05 1972-02-10 Koehring Company Inc Steuerventil
GB1406469A (en) * 1971-12-27 1975-09-17 Caterpillar Tractor Co Hydraulic flow control system
DE2751613A1 (de) * 1977-11-18 1979-05-23 Tadeusz Budzich Lastabhaengiges stromregelsystem

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE908541C (de) * 1940-06-15 1954-04-08 Askania Werke Ag Selbsttaetiger Regler mit Kraftschalter
US2503870A (en) * 1946-05-03 1950-04-11 Vickers Inc Flow regulating device
GB944167A (en) * 1959-03-03 1963-12-11 Heinz Teves Improvements in or relating to hydraulic circuits
DE1911131A1 (de) * 1969-03-05 1970-09-17 Buchholz Helmut Hydraulische Steuereinrichtung
DE2038813A1 (de) * 1970-08-05 1972-02-10 Koehring Company Inc Steuerventil
GB1406469A (en) * 1971-12-27 1975-09-17 Caterpillar Tractor Co Hydraulic flow control system
DE2751613A1 (de) * 1977-11-18 1979-05-23 Tadeusz Budzich Lastabhaengiges stromregelsystem

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0170815A1 (de) * 1984-07-10 1986-02-12 Robert Bosch Gmbh Hydraulische Steuereinrichtung

Also Published As

Publication number Publication date
CA1179916A (en) 1984-12-27
EP0064332B1 (de) 1985-07-24
DE3264859D1 (en) 1985-08-29
JPS57184707A (en) 1982-11-13

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