EP0610940A1 - Regulator for a variable displacement pump - Google Patents
Regulator for a variable displacement pump Download PDFInfo
- Publication number
- EP0610940A1 EP0610940A1 EP94102088A EP94102088A EP0610940A1 EP 0610940 A1 EP0610940 A1 EP 0610940A1 EP 94102088 A EP94102088 A EP 94102088A EP 94102088 A EP94102088 A EP 94102088A EP 0610940 A1 EP0610940 A1 EP 0610940A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- piston
- servo
- pump
- variable displacement
- working pressure
- 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
Links
Images
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
- F04B49/002—Hydraulic systems to change the pump delivery
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
- F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
- F04B1/14—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis having stationary cylinders
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
- F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
- F04B1/26—Control
- F04B1/30—Control of machines or pumps with rotary cylinder blocks
- F04B1/32—Control of machines or pumps with rotary cylinder blocks by varying the relative positions of a swash plate and a cylinder block
- F04B1/324—Control of machines or pumps with rotary cylinder blocks by varying the relative positions of a swash plate and a cylinder block by changing the inclination of the swash plate
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
- F04B49/08—Regulating by delivery pressure
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B2201/00—Pump parameters
- F04B2201/12—Parameters of driving or driven means
- F04B2201/1204—Position of a rotating inclined plate
Definitions
- the present invention relates to a regulator for a variable displacement pump; and, more particularly, to a regulator provided with a hydraulic servo controller capable of controlling the displacement volume of the pump and accomplishing a feedback function depending upon the working pressure from the pump, an effective spring force and a pilot pressure to achieve a stable flow rate and reduce energy losses.
- a conventional variable displacement pump comprises a regulator which employs a device for controlling the angle of a swash plate therein.
- a regulator comprising: a valve body; means for controlling the angle of a swash plate; a directional changeover valve defining a position for supplying a working pressure to a first chamber, a position for sealing the first chamber and a position for discharging the load pressure from the first chamber; a feedback lever for connecting an end of the changeover valve with a servo-piston of the control means; a first pilot spool movable by the working pressure from the pump for controlling the horsepower thereof; a second pilot spool movable by the pilot pressure, wherein a reservoir pressure is included, for controlling the flow rate of the pump; and a linkage mechanism for selectively applying one of the first and the second pilot spools to the feedback lever to reduce the discharge flow rate thereof.
- the linkage mechanism of the regulator complicates the overall structure and construction thereof. Further, since the flow rate of the pump is likely to be affected by a variation in the reservoir pressure of the hydraulic system during the flow rate control, it is difficult to achieve and maintain a predetermined target flow rate. In addition, the regulator is handicapped by the absence of a flow rate cutoff control and a flow rate cutoff release control, thereby causing an energy loss due to its inability to prevent an unnecessary discharge flow.
- variable displacement pump incorporating therein a regulator for controlling the flow rate of a fluid therein by means of varying the angle of a swash plate
- a pump for producing a flow of the fluid a valve body in fluid-communication with the pump; a servo-piston pivotally mounted to the swash plate and provided with two portions, each having a different diameter, which are movable along a first and a second chambers formed within the valve body; a multi-stage piston movable along a first and a second piston compartments in the valve body by a working pressure from the pump; a control rod movable along an axis of the servo-piston and having a servo-spool for changing the direction of the flow; a servo-sleeve in fluid-communication with the servo spool for defining a neutral position, a position for supplying the working pressure of the second chamber and a position for discharging the
- a regulator 10 in accordance with the present invention.
- a pair of variable displacement pumps Pd1 and Pd2 driven by an engine 12 produce a flow rate for the hydraulic pumps Pd1, Pd 2, which is controlled by means of varying the angle of a swash plate 14.
- a gear pump Pg is also driven by the engine 12 to deliver a pilot pressure to the regulator 10.
- a valve body 11 is installed to be fluid communicable with the pumps Pd1,Pd2 and Pg.
- the swash plate 14 is pivotally mounted to a servo-piston 16 at its one portion of the periphery thereof by a connecting rod 18 fixed to the servo-piston 16.
- the servo-piston 16 has two portions: i.e., portion a having a relatively small diameter and portion b having a relatively large diameter, each of which is slidably movable along a first chamber 20 and a second chamber 22 formed within the valve body 11.
- the first chamber 20 is fluid communicable with the pump Pd1 while the second chamber 22 is fluid communicable with a reservoir 24 through a cutoff spool 26 and a servo-spool 28 having a changeover recess 30.
- a servo-sleeve 34 has three holes 31, 32, 33 for defining a neutral position as shown in Fig.
- a control rod 36 is connected to the servo-piston 16 by a first and a second springs 38, 40 capable of transmitting to the servo spool 28 the difference between the forces acted on the control rod 36 and the servo-piston 16, thereby changing or adjusting the hole position of the servo-sleeve 34.
- a multi-stage piston 42 in contact with the control rod 36 is slidably located in a first and a second piston compartments 44, 46, having a plurality of stages, each of which has a different diameter. As shown in Fig. 2, the control rod 36, the servo-piston 16, the multi-stage piston 42, and the springs 38,40 and 66 have a coaxial relationship with one another.
- the working pressure from the pumps Pd1, Pd2 is supplied to the first and the second piston compartments 44, 46 through pressure lines 48, 50, and a pilot pressure is applied to a pilot chamber 52, a drain chamber 54 and a third piston chamber 56 through pilot lines 58, 60 from a control valve 64 and a line 62 through a reducing valve 76 from the gear pump Pg.
- the gear pump Pg is installed to maintain a constant initial pressure of the hydraulic circuitry to thereby prevent a delayed response time of the regulator 10 at a low working pressure.
- the working pressure initially supplied to the first chamber 20 is the higher one of the working pressure of the pump Pd1 and the gear pump Pg.
- the hydraulically pressurized area of the servo-piston 16 located in the second chamber 22 is broader than that located in the first chamber 20, the movement to the left side of the servo-piston 16 decreases the angle of the swash plate 14 to thereby reduce the dicharge flow rate from the pumps and tends to urge the outer spring 38 against the control rod 36. Consequently, the control rod 36 is moved to the left to reduce the area, through which the flow is passed, formed by the relative position of the holes 31,32 and 33 of the servo-sleeve 34 and the recess 30 of the servo-spool 28, thereby decreasing the working pressure supplied to the second chamber 22.
- the working pressure supplied to a first cutoff piston compartment 70 overcomes the resilient force of a fourth spring 72 so that the cutoff spool 26 is moved to directly supply the working pressure into the second chamber 22.
- the servo-piston 16 is moved to reduce the angle of the swash plate 14, thereby reducing the discharge flow rate of the pumps up to its minimum value, i.e., point D shown in Fig. 3.
- the flow rate cutoff control therefore minimizes the energy loss by reducing the discharge flow rate up to the minimum value.
- variable displacement pump requires the flow rate more than that of the section C-D
- a pilot pressure Pcf from the exterior(shown in dotted lines) is supplied into a second cutoff piston compartments 74.
- the recovering force of the fourth spring 72 added to the pilot pressure Pcf in the second cutoff piston compartment 74 defeats the working pressure in the first cutoff piston compartment 70 to ensure that the second chamber 22 is communicated with the reservoir 24 through the hole 31 of the servo spool 28 via the cut off spool 26, although the working pressure higher than the point C is supplied therein.
- the servo-piston 16 is moved to increase the discharge flow rate of the pumps Pd1 and Pd2 more than their minimum flow rate, thereby releasing the flow rate cutoff control.
- Fig. 4 illustrates a graph showing the relationship between the pilot pressure and the flow rate.
- the pilot pressure Pc from the control valve 64 is directly supplied to the pilot chamber 52 through the line 58 and the pilot pressure Pcf is supplied to the drain chamber 54 via an orifice 65 through a line 60.
- the pilot pressure Pc has a higher value than that of the pilot pressure Pcf.
- the flow rate control is accomplished by the pressure difference ⁇ P between the pressure Pc in the pilot chamber 52 and the pressure Pcd of the drain chamber 54 as shown in Fig. 4, wherein its operational process is similar that of Fig. 3.
- FIG. 3 there is shown another horsepower control diagram, i.e., line A''-B''-C'', accomplished by a pilot pressure Pps from the gear pump Pg.
- the pilot pressure Pps from is supplied into the third piston compartment 56 to increase the working pressure applied to the multi-stage piston 42.
- the resultant force acted on the multistage piston 42 urges the control rod 36 so that the discharge flow rate begins to be reduced to control the horsepower constantly along the line A''-B''-C'' shown in Fig. 3, when the working pressure is lower than the point A'', wherein its operational process is similar to that of the line A-B-C shown in Fig. 3.
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Control Of Positive-Displacement Pumps (AREA)
- Reciprocating Pumps (AREA)
- Rotary Pumps (AREA)
Abstract
Description
- The present invention relates to a regulator for a variable displacement pump; and, more particularly, to a regulator provided with a hydraulic servo controller capable of controlling the displacement volume of the pump and accomplishing a feedback function depending upon the working pressure from the pump, an effective spring force and a pilot pressure to achieve a stable flow rate and reduce energy losses.
- A conventional variable displacement pump comprises a regulator which employs a device for controlling the angle of a swash plate therein. For example, Japanese Laid-Open Publication No. 89-116294 discloses a regulator comprising: a valve body; means for controlling the angle of a swash plate; a directional changeover valve defining a position for supplying a working pressure to a first chamber, a position for sealing the first chamber and a position for discharging the load pressure from the first chamber; a feedback lever for connecting an end of the changeover valve with a servo-piston of the control means; a first pilot spool movable by the working pressure from the pump for controlling the horsepower thereof; a second pilot spool movable by the pilot pressure, wherein a reservoir pressure is included, for controlling the flow rate of the pump; and a linkage mechanism for selectively applying one of the first and the second pilot spools to the feedback lever to reduce the discharge flow rate thereof.
- However, the linkage mechanism of the regulator complicates the overall structure and construction thereof. Further, since the flow rate of the pump is likely to be affected by a variation in the reservoir pressure of the hydraulic system during the flow rate control, it is difficult to achieve and maintain a predetermined target flow rate. In addition, the regulator is handicapped by the absence of a flow rate cutoff control and a flow rate cutoff release control, thereby causing an energy loss due to its inability to prevent an unnecessary discharge flow.
- Accordingly, it is an object of the present invention to provide a regulator for a variable displacement pump having a simplified structure by eliminating the linkage mechanism.
- It is another object of the present invention to provide a regulator for a variable displacement pump capable of accomplishing a stable flow rate control by eliminating the effect of the reservoir pressure of the hydraulic system.
- It is still another object of the present invention to provide a regulator for a variable displacement pump capable of reducing an energy loss by providing a flow rate cutoff control when the working pressure is greater than a predetermined value.
- The above and other objects of the present invention are accomplished by means of a variable displacement pump incorporating therein a regulator for controlling the flow rate of a fluid therein by means of varying the angle of a swash plate, which comprises: a pump for producing a flow of the fluid; a valve body in fluid-communication with the pump; a servo-piston pivotally mounted to the swash plate and provided with two portions, each having a different diameter, which are movable along a first and a second chambers formed within the valve body; a multi-stage piston movable along a first and a second piston compartments in the valve body by a working pressure from the pump; a control rod movable along an axis of the servo-piston and having a servo-spool for changing the direction of the flow; a servo-sleeve in fluid-communication with the servo spool for defining a neutral position, a position for supplying the working pressure of the second chamber and a position for discharging the working pressure to a reservoir; a cut-off spool in fluid-communication with the servo sleeve for defining a position for supplying the working pressure from the pump to the second chamber and a position for discharging the working pressure from the second chamber to the servo sleeve; and means for biasing the control rod and the servo-piston to be spaced apart from each other.
- The above and other objects, advantages and features of the present invention will be apparent from the following description of preferred embodiments taken in conjunction with the accompanying drawings, wherein:
- Fig. 1 is a circuit diagram of a regulator for a variable displacement pump in accordance with the present invention;
- Fig. 2 is a cross-sectional view of one embodiment of the regulator in accordance with the present invention;
- Fig. 3 is a graph showing the relationship between the flow rate and the working pressure; and
- Fig. 4 is a graph illustrating the relationship between the flow rate and the pilot pressure.
- Referring to Figs. 1 and 2, there is shown a
regulator 10 in accordance with the present invention. A pair of variable displacement pumps Pd₁ and Pd₂ driven by anengine 12 produce a flow rate for the hydraulic pumps Pd₁, Pd2, which is controlled by means of varying the angle of aswash plate 14. A gear pump Pg is also driven by theengine 12 to deliver a pilot pressure to theregulator 10. Avalve body 11 is installed to be fluid communicable with the pumps Pd₁,Pd₂ and Pg. Theswash plate 14 is pivotally mounted to a servo-piston 16 at its one portion of the periphery thereof by a connectingrod 18 fixed to the servo-piston 16. The servo-piston 16 has two portions: i.e., portion a having a relatively small diameter and portion b having a relatively large diameter, each of which is slidably movable along afirst chamber 20 and asecond chamber 22 formed within thevalve body 11. Thefirst chamber 20 is fluid communicable with the pump Pd₁ while thesecond chamber 22 is fluid communicable with areservoir 24 through acutoff spool 26 and a servo-spool 28 having a changeover recess 30. A servo-sleeve 34 has threeholes second chamber 22 via the cut offspool 26 and a position for discharging the working pressure to thereservoir 24. Acontrol rod 36 is connected to the servo-piston 16 by a first and asecond springs servo spool 28 the difference between the forces acted on thecontrol rod 36 and the servo-piston 16, thereby changing or adjusting the hole position of the servo-sleeve 34. Amulti-stage piston 42 in contact with thecontrol rod 36 is slidably located in a first and asecond piston compartments control rod 36, the servo-piston 16, themulti-stage piston 42, and thesprings - The working pressure from the pumps Pd₁, Pd₂ is supplied to the first and the
second piston compartments pressure lines pilot chamber 52, adrain chamber 54 and athird piston chamber 56 throughpilot lines control valve 64 and aline 62 through a reducing valve 76 from the gear pump Pg. The gear pump Pg is installed to maintain a constant initial pressure of the hydraulic circuitry to thereby prevent a delayed response time of theregulator 10 at a low working pressure. Thus, the working pressure initially supplied to thefirst chamber 20 is the higher one of the working pressure of the pump Pd₁ and the gear pump Pg. - Hereinafter, how the regulator operates, depending upon the working pressure applied to each of the circuit elements, will be described with reference to the accompanying drawings. First, when the working pressure from the pumps is lower than the recovering force of the
third spring 66, the movement toward the left side of the servo-spool 28 causes thesecond chamber 22 to be fluid communicated with thereservoir 24. Therefore, since the working pressure applied in thefirst chamber 20 is greater than that in thesecond chamber 22, the movement to the right side of the servo-piston 16 increases the angle of theswash plate 14 so that the discharge flow rate from the pumps may reach up to its maximum level. - On the other hand, when the summation of the working pressures from the pumps Pd₁, Pd₂ is higher than point A shown in Fig. 3, the working pressures supplied to the first and the
second piston compartments springs control rod 36 to the right. At the same time, the cut offspool 26 also moves to the right by the action of the working pressure from aline 68 to have theholes second chambers piston 16 located in thesecond chamber 22 is broader than that located in thefirst chamber 20, the movement to the left side of the servo-piston 16 decreases the angle of theswash plate 14 to thereby reduce the dicharge flow rate from the pumps and tends to urge theouter spring 38 against thecontrol rod 36. Consequently, thecontrol rod 36 is moved to the left to reduce the area, through which the flow is passed, formed by the relative position of theholes sleeve 34 and therecess 30 of the servo-spool 28, thereby decreasing the working pressure supplied to thesecond chamber 22. When the working pressure in thesecond chamber 22 becomes lower than that in thefirst chamber 20 again, the servo-piston 16 is moved to the right and thecontrol rod 36 is also moved to the right due to a relaxation of thespring 38. Accordingly, the reciprocating movement of thecontrol rod 36 does not stop until the resultant pressure balance among the working pressures in thechambers springs - Further, when the summation of the working pressures from the pumps Pd1 and Pd2 is greater than the point B shown in Fig. 3, the
control rod 36 becomes urged against thesprings springs - Furthermore, when the working pressure becomes greater than point C shown in Fig. 3, the working pressure supplied to a first
cutoff piston compartment 70 overcomes the resilient force of afourth spring 72 so that thecutoff spool 26 is moved to directly supply the working pressure into thesecond chamber 22. Thus, the servo-piston 16 is moved to reduce the angle of theswash plate 14, thereby reducing the discharge flow rate of the pumps up to its minimum value, i.e., point D shown in Fig. 3. The flow rate cutoff control, therefore minimizes the energy loss by reducing the discharge flow rate up to the minimum value. - In contrast, when the variable displacement pump requires the flow rate more than that of the section C-D, a pilot pressure Pcf from the exterior(shown in dotted lines) is supplied into a second
cutoff piston compartments 74. Thus, the recovering force of thefourth spring 72 added to the pilot pressure Pcf in the secondcutoff piston compartment 74 defeats the working pressure in the firstcutoff piston compartment 70 to ensure that thesecond chamber 22 is communicated with thereservoir 24 through thehole 31 of theservo spool 28 via the cut offspool 26, although the working pressure higher than the point C is supplied therein. Accordingly, the servo-piston 16 is moved to increase the discharge flow rate of the pumps Pd1 and Pd2 more than their minimum flow rate, thereby releasing the flow rate cutoff control. - Fig. 4 illustrates a graph showing the relationship between the pilot pressure and the flow rate. First, referring to Fig. 1, the pilot pressure Pc from the
control valve 64 is directly supplied to thepilot chamber 52 through theline 58 and the pilot pressure Pcf is supplied to thedrain chamber 54 via anorifice 65 through aline 60. Thus, the pilot pressure Pc has a higher value than that of the pilot pressure Pcf. Accordingly, the flow rate control is accomplished by the pressure difference \P between the pressure Pc in thepilot chamber 52 and the pressure Pcd of thedrain chamber 54 as shown in Fig. 4, wherein its operational process is similar that of Fig. 3. - Turning now to Fig. 3, there is shown another horsepower control diagram, i.e., line A''-B''-C'', accomplished by a pilot pressure Pps from the gear pump Pg. The pilot pressure Pps from is supplied into the
third piston compartment 56 to increase the working pressure applied to themulti-stage piston 42. The resultant force acted on themultistage piston 42 urges thecontrol rod 36 so that the discharge flow rate begins to be reduced to control the horsepower constantly along the line A''-B''-C'' shown in Fig. 3, when the working pressure is lower than the point A'', wherein its operational process is similar to that of the line A-B-C shown in Fig. 3. - Although the invention has been shown and described with respect to the exemplary embodiments, it should be understood by those skilled in the art that various changes, modifications and additions may be made, without departing from the spirit and scope of the invention.
Claims (6)
- A variable displacement pump incorporating therein a regulator for controlling the flow rate of a fluid therein by means of varying the angle of a swash plate, which comprises:
a pump for producing a flow of the fluid;
a valve body in fluid-communication with the pump;
a servo-piston pivotally mounted to the swash plate and provided with two portions, each having a different diameter, which are movable along a first and a second chambers formed within the valve body;
a multi-stage piston movable along a first and a second piston compartments in the valve body by a working pressure from the pump;
a control rod movable along an axis of the servo-piston and having a servo-spool for changing the direction of the flow;
a servo-sleeve in fluid-communication with the servo spool for defining a neutral position, a position for supplying the working pressure of the second chamber and a position for discharging the working pressure to a reservoir;
a cut-off spool in fluid-communication with the servo sleeve for defining a position for supplying the working pressure from the pump to the second chamber and a position for discharging the working pressure from the second chamber to the servo sleeve; and
means for biasing the control rod and the servo-piston to be spaced apart from each other. - The variable displacement pump as recited in claim 1, wherein said variable displacement pump further comprises a control valve for supplying a pilot pressure to a pilot chamber in which the control rod is located, and a drain chamber.
- The variable displacement pump as recited in claim 1, wherein said cutoff spool has a cutoff piston, movable along a first and a second cutoff piston compartments communicating with the pump and a pilot line.
- The variable displacement pump recited in claim 1, wherein said biasing means has an outer spring located between the control rod and the servo-piston and an inner spring, having a smaller diameter and a shorter length than those of the outer spring, which is located within the outer spring.
- The variable displacement pump as recited in claim 1, wherein said pilot pressure from the gear pump is supplied via a reducing valve to a third piston compartment formed with in the valve body to increase the working pressure applied to the multi-stage piston.
- The variable displacement pump as recited in claim 1, wherein said control rod, said servo-piston, said multi-stage piston and said springs have a coaxial relatoinship with one another.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR931848 | 1993-02-11 | ||
KR1019930001848A KR950013009B1 (en) | 1993-02-11 | 1993-02-11 | Wobble plate pump |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0610940A1 true EP0610940A1 (en) | 1994-08-17 |
EP0610940B1 EP0610940B1 (en) | 1996-09-25 |
Family
ID=19350668
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP94102088A Expired - Lifetime EP0610940B1 (en) | 1993-02-11 | 1994-02-10 | Regulator for a variable displacement pump |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0610940B1 (en) |
KR (1) | KR950013009B1 (en) |
CN (1) | CN1033052C (en) |
DE (1) | DE69400583T2 (en) |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0761966A2 (en) * | 1995-09-12 | 1997-03-12 | Caterpillar Inc. | Pump displacement control for a variable displacement pump |
EP0897062A2 (en) * | 1997-08-13 | 1999-02-17 | Brueninghaus Hydromatik Gmbh | Pressure control circuit for more than one hydraulic pump with a pressure averager |
US6623247B2 (en) * | 2001-05-16 | 2003-09-23 | Caterpillar Inc | Method and apparatus for controlling a variable displacement hydraulic pump |
US6848254B2 (en) | 2003-06-30 | 2005-02-01 | Caterpillar Inc. | Method and apparatus for controlling a hydraulic motor |
CN108591151A (en) * | 2018-02-05 | 2018-09-28 | 江苏恒立液压科技有限公司 | Hydraulic axial plunger pump power control and positive flow control mechanism |
CH714321A1 (en) * | 2017-11-11 | 2019-05-15 | Liebherr Machines Bulle Sa | Adjusting device for an axial piston machine. |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102010020004A1 (en) * | 2010-03-05 | 2011-09-08 | Robert Bosch Gmbh | Control device and method for controlling a torque of a drive shaft of a hydrostatic machine |
DE102011120082A1 (en) * | 2011-12-05 | 2013-06-06 | Man Truck & Bus Ag | Adjusting device, in particular for motor vehicles |
CN103511369A (en) * | 2013-09-11 | 2014-01-15 | 中航力源液压股份有限公司 | Multi-gear power control variable piston pump |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3834836A (en) * | 1973-03-01 | 1974-09-10 | Caterpillar Tractor Co | Override control for a variable displacement pump |
US4381646A (en) * | 1980-09-12 | 1983-05-03 | Caterpillar Tractor Co. | Torque and high pressure limiting control for variable displacement pumps |
EP0549883A1 (en) * | 1991-11-30 | 1993-07-07 | Samsung Heavy Industries Co., Ltd | Control system for hydraulic pumps of the variable displacement type |
EP0576727A1 (en) * | 1992-05-30 | 1994-01-05 | Samsung Heavy Industries Co., Ltd | Control systems for variable displacement hydraulic pumps |
-
1993
- 1993-02-11 KR KR1019930001848A patent/KR950013009B1/en not_active IP Right Cessation
-
1994
- 1994-02-10 EP EP94102088A patent/EP0610940B1/en not_active Expired - Lifetime
- 1994-02-10 DE DE69400583T patent/DE69400583T2/en not_active Expired - Fee Related
- 1994-02-10 CN CN94102775A patent/CN1033052C/en not_active Expired - Fee Related
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3834836A (en) * | 1973-03-01 | 1974-09-10 | Caterpillar Tractor Co | Override control for a variable displacement pump |
US4381646A (en) * | 1980-09-12 | 1983-05-03 | Caterpillar Tractor Co. | Torque and high pressure limiting control for variable displacement pumps |
EP0549883A1 (en) * | 1991-11-30 | 1993-07-07 | Samsung Heavy Industries Co., Ltd | Control system for hydraulic pumps of the variable displacement type |
EP0576727A1 (en) * | 1992-05-30 | 1994-01-05 | Samsung Heavy Industries Co., Ltd | Control systems for variable displacement hydraulic pumps |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0761966A2 (en) * | 1995-09-12 | 1997-03-12 | Caterpillar Inc. | Pump displacement control for a variable displacement pump |
EP0761966A3 (en) * | 1995-09-12 | 1997-04-02 | Caterpillar Inc. | Pump displacement control for a variable displacement pump |
EP0897062A2 (en) * | 1997-08-13 | 1999-02-17 | Brueninghaus Hydromatik Gmbh | Pressure control circuit for more than one hydraulic pump with a pressure averager |
EP0897062A3 (en) * | 1997-08-13 | 1999-12-01 | Brueninghaus Hydromatik Gmbh | Pressure control circuit for more than one hydraulic pump with a pressure averager |
US6623247B2 (en) * | 2001-05-16 | 2003-09-23 | Caterpillar Inc | Method and apparatus for controlling a variable displacement hydraulic pump |
US6848254B2 (en) | 2003-06-30 | 2005-02-01 | Caterpillar Inc. | Method and apparatus for controlling a hydraulic motor |
CH714321A1 (en) * | 2017-11-11 | 2019-05-15 | Liebherr Machines Bulle Sa | Adjusting device for an axial piston machine. |
CN108591151A (en) * | 2018-02-05 | 2018-09-28 | 江苏恒立液压科技有限公司 | Hydraulic axial plunger pump power control and positive flow control mechanism |
CN108591151B (en) * | 2018-02-05 | 2023-11-21 | 江苏恒立液压科技有限公司 | Hydraulic axial plunger pump power control and positive flow control mechanism |
Also Published As
Publication number | Publication date |
---|---|
DE69400583D1 (en) | 1996-10-31 |
KR940019991A (en) | 1994-09-15 |
CN1033052C (en) | 1996-10-16 |
EP0610940B1 (en) | 1996-09-25 |
KR950013009B1 (en) | 1995-10-24 |
DE69400583T2 (en) | 1997-02-06 |
CN1094794A (en) | 1994-11-09 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US4456434A (en) | Power transmission | |
EP0637692A1 (en) | Displacement controlled hydraulic proportional valve | |
US4293284A (en) | Power limiting control apparatus for pressure-flow compensated variable displacement pump assemblies | |
KR970074159A (en) | Hydraulic devices for operating car control elements | |
KR19990063096A (en) | Load Sensing Priority Hydraulic Control Valve System | |
EP0761966B1 (en) | Pump displacement control for a variable displacement pump | |
EP2933486B1 (en) | Pump volume control device | |
EP0610940B1 (en) | Regulator for a variable displacement pump | |
JPH0463244B2 (en) | ||
US5586869A (en) | Initial pressure governor for a variable displacement pump | |
EP0667452B1 (en) | Capacity control device in variable capacity hydraulic pump | |
EP1241356B1 (en) | Hydraulic circuit for a fluid motor | |
US5279122A (en) | Hydraulic circuit apparatus for supplying fluid under pressure into hydraulic cylinders for work implement | |
US5081905A (en) | Hydraulic pilot operation circuit and valve for quickly discharging oil | |
US4244678A (en) | Displacement control system for variable displacement pump | |
EP0015069B1 (en) | Fluid actuated constant output power control for variable delivery pump | |
GB2291986A (en) | Fluid pressure control system for hydraulic excavators | |
EP0153065B1 (en) | Variable displacement pump system | |
JP2929021B2 (en) | Variable displacement pump | |
US4366672A (en) | Pilot operated hydraulic device | |
US5735311A (en) | Pressure compensation valve | |
JPH0617761A (en) | Power controller for at least two variable discharge hydraulic pump | |
JP2634969B2 (en) | Hydraulic drive and unload valve for civil engineering and construction machinery | |
JP3685287B2 (en) | Capacity controller for variable displacement hydraulic pump | |
JPH0758081B2 (en) | Hydraulic drive system |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
17P | Request for examination filed |
Effective date: 19940210 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): BE DE FR GB |
|
17Q | First examination report despatched |
Effective date: 19951121 |
|
GRAH | Despatch of communication of intention to grant a patent |
Free format text: ORIGINAL CODE: EPIDOS IGRA |
|
GRAA | (expected) grant |
Free format text: ORIGINAL CODE: 0009210 |
|
GRAH | Despatch of communication of intention to grant a patent |
Free format text: ORIGINAL CODE: EPIDOS IGRA |
|
AK | Designated contracting states |
Kind code of ref document: B1 Designated state(s): BE DE FR GB |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: FR Effective date: 19960925 Ref country code: BE Effective date: 19960925 |
|
REF | Corresponds to: |
Ref document number: 69400583 Country of ref document: DE Date of ref document: 19961031 |
|
EN | Fr: translation not filed | ||
PLBE | No opposition filed within time limit |
Free format text: ORIGINAL CODE: 0009261 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT |
|
26N | No opposition filed | ||
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: GB Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 19980210 |
|
GBPC | Gb: european patent ceased through non-payment of renewal fee |
Effective date: 19980210 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: DE Payment date: 19990429 Year of fee payment: 6 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: DE Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20001201 |