JP2014190255A - Pump control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pump control device for controlling a discharge capacity of a pump by using a regulator of a simple structure.SOLUTION: A spool 70 of a regulator 40 adjusts a control pressure Pc led to an actuator 16 while applying the highest discharge pressure P1, P2 among the discharge pressures of the working fluid discharged from the plurality of discharge ports as an original pressure, when moving by receiving an average discharge pressure Pave obtained by averaging discharge pressures P1, P2 of a working fluid discharged from the plurality of discharge ports of a pump by a driving pressure receiving surface 72A formed inside of the spool 70, and further adjusts the control pressure Pc when moving by receiving a horse power control signal pressure Pi by a signal pressure receiving surface 78A of an outer peripheral step portion 78.

Description

  The present invention relates to a pump control device that controls the discharge capacity of a pump.

  2. Description of the Related Art Conventionally, a swash plate type multiple piston pump that is driven to rotate by an engine is used as a driving pressure source of hydraulic equipment mounted on a working machine such as a hydraulic excavator. This piston pump has two sets of suction ports and discharge ports, and hydraulic oil is discharged from each discharge port.

  Patent Document 1 discloses a pump control device that controls the discharge capacity of a swash plate type multiple piston pump. This pump control device is equipped with a regulator that controls the tilt angle of the swash plate so as to make the work rate of the piston pump constant, and the discharge pressure introduced from each discharge port is averaged as the original pressure led to this regulator. An average discharge pressure is used.

  Patent Document 2 discloses a regulator that controls the discharge capacity of a pump in accordance with a signal pressure derived when a device such as an air conditioner operates in a piston pump driven by an engine.

JP 2008-291732 A JP 2008-240518 A

  However, in such a conventional pump control device, there is a problem that, as the number of signal pressures increases, the spool constituting the regulator increases in size and the structure of the regulator becomes complicated. It was.

  The present invention has been made in view of the above problems, and an object thereof is to provide a pump control device that controls the discharge capacity of a pump using a regulator having a simple structure even when the number of signal pressures increases. And

  The present invention is a pump control device that controls the discharge capacity of a pump that discharges working fluid from a plurality of discharge ports, and includes an actuator that changes the discharge capacity of the pump and a regulator that adjusts the control pressure guided to the actuator. The regulator includes a drive pressure port that leads to an average discharge pressure that is an average of the discharge pressures of the working fluid discharged from the plurality of discharge ports, and the highest high-pressure side discharge pressure of the working fluid discharged from the plurality of discharge ports. An original pressure port through which the signal pressure is guided, a signal pressure port through which the signal pressure is guided, and a spool that adjusts the control pressure using the high-pressure side discharge pressure as the original pressure by moving by receiving the average discharge pressure and the signal pressure, A drive pressure receiving surface for receiving an average discharge pressure is formed inside the spool, and a signal pressure receiving surface for receiving a signal pressure is formed on the outer peripheral step portion of the spool.

  According to the present invention, the spool of the regulator moves by receiving an average discharge pressure obtained by averaging the discharge pressures of the working fluid discharged from the plurality of discharge ports of the pump on the driving pressure receiving surface formed inside the spool, and moves the plurality of discharges. The control pressure guided to the actuator is adjusted with the highest discharge pressure of the working fluid discharged from the outlet as the original pressure. Further, the spool also adjusts the control pressure by moving the signal pressure received on the signal pressure receiving surface of the outer peripheral step portion. As a result, the pump control device can suppress an increase in the size of the spool even when the number of signal pressures increases, and can control the discharge capacity of the pump using a regulator having a simple structure.

1 is a hydraulic circuit diagram of a pump control device according to an embodiment of the present invention. It is sectional drawing of the regulator which concerns on embodiment of this invention. It is a characteristic view which shows the relationship between the signal pressure of the pump control apparatus which concerns on embodiment of this invention, and discharge capacity.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  A pump control device 1 shown in FIG. 1 is provided in a drive pressure source of a hydraulic device mounted on a hydraulic excavator, and controls a discharge capacity (pump displacement) of a variable capacity pump 11.

  As the variable displacement pump 11 (hereinafter simply referred to as “pump 11”), for example, a swash plate type multiple piston pump is used. The pump 11 includes one suction port and two discharge ports.

  The pump 11 is driven by the engine 10 and sucks hydraulic oil from each suction port through a suction passage 20 from a tank port 30 connected to a tank (not shown) and reciprocates following the swash plate 15 (not shown). And are discharged from each discharge port.

  The hydraulic oil discharged from each discharge port passes through the first discharge passage 21 and the second discharge passage 22, the pump ports 31, 32, and the control valve (not shown), respectively, to the boom, arm, and bucket of the hydraulic excavator. It is distributed to each hydraulic cylinder to be driven and left and right traveling motors.

  The hydraulic oil having the pressure P1 discharged from one discharge port is supplied to the left travel motor through the first discharge passage 21. The hydraulic oil having the pressure P2 discharged from the other discharge port is supplied to the right travel motor through the second discharge passage 22. The control valve adjusts the flow rate of the hydraulic oil supplied to the left and right traveling motors, thereby stopping the vehicle, traveling straight, and turning.

  The pump control device 1 is provided with a first constant displacement pump 12 and a second constant displacement pump 13 along with the pump 11. The first constant displacement pump 12 and the second constant displacement pump 13 are driven by an engine 10 that is a common drive source with the pump 11. As the first constant capacity pump 12 and the second constant capacity pump 13, for example, a gear pump is used, and the discharge capacity is made constant.

  The first constant capacity pump 12 sucks the working oil through the suction passage 25 branched from the suction passage 20 and sends the pressurized working oil to the pump port 39 through the third discharge passage 23. This hydraulic oil is supplied to a turning motor that turns a cab (driver's seat) of a hydraulic excavator by a control valve (not shown) connected to the pump port 39.

  The second constant capacity pump 13 sucks the working oil through the suction passage 26 branched from the suction passage 25 and sends the pressurized working oil to the signal pressure port 34 through the signal pressure passage 24. The hydraulic oil is supplied to a hydraulic drive unit that switches the control valve through a signal pressure passage (not shown) connected to the signal pressure port 34.

  As the working fluid supplied to and discharged from the pump 11, the first constant capacity pump 12, and the second constant capacity pump 13, working oil (oil) is used. In addition to the working oil, working fluid such as a water-soluble alternative liquid is used. May be used.

  Next, a configuration for controlling the discharge capacity of the pump 11 will be described.

  The swash plate type piston type pump 11 includes a cylinder block (not shown) that is rotationally driven by the engine 10, a piston that reciprocates in a cylinder of the cylinder block, and discharges the working oil sucked in, and this piston follows. The swash plate 15, the horsepower control springs 48 and 49 that urge the swash plate 15 in the direction of increasing the tilt angle, and the small diameter that drives the swash plate 15 in the same direction as the spring force of the horsepower control springs 48 and 49. An actuator 47 and a large-diameter actuator 16 (hereinafter simply referred to as “actuator 16”) that drives the swash plate 15 against the spring force of the horsepower control springs 48 and 49 and the driving force of the small-diameter actuator 47 are provided. . The multiple pump 11 includes one suction port and two discharge ports (not shown), a cylinder communicating with the first discharge passage 21 in the cylinder block, and a cylinder communicating with the second discharge passage 22. .

  When the tilt angle of the swash plate 15 is changed by the operation of the actuator 16, the pump 11 changes the discharge capacity by changing the stroke in which the piston reciprocates following the swash plate 15.

  The actuator 16 reduces the tilt angle of the swash plate 15 and decreases the discharge capacity of the pump 11 as the control pressure Pcg guided thereby increases.

  The pump control device 1 includes a load sensing regulator 60 (hereinafter simply referred to as “LS regulator 60”) that adjusts the control pressure Pcg guided to the actuator 16, and an operating hydraulic pressure (control pressure) guided to the LS regulator 60. A horsepower control regulator 40 (hereinafter simply referred to as “regulator 40”) for adjusting Pc is provided.

  A throttle 57 is interposed in the second control pressure passage 56 so that the pressure fluctuation of the control pressure Pcg guided to the actuator 16 is reduced. The control pressure Pcg generated in the second control pressure passage 56 is taken out from the control pressure port 35 and detected by a pressure sensor (not shown).

  The regulator 40 is a 3-port 2-position switching valve, and includes a spool 70 (see FIG. 2) that moves between positions a and b. The spool 70 is given the spring force of the horsepower control springs 48 and 49, and the discharge pressures P1 and P2 of the working fluid discharged to each discharge port are averaged as a signal pressure (drive pressure) against the spring force. The average discharge pressure Pave is guided through the discharge pressure signal passage 63. The spool 70 moves to a position where the average discharge pressure Pave and the spring force of the horsepower control springs 48 and 49 are balanced to adjust the opening degree of the positions a and b.

  The discharge pressure signal passage 63 includes a first discharge pressure signal passage 61 and a second discharge pressure signal passage 62 branched from the first discharge passage 21 and the second discharge passage 22, respectively. Restrictions 64 and 65 are interposed in the two discharge pressure signal passages 62. The discharge pressure P1 generated in the first discharge passage 21 is guided to the discharge pressure signal passage 63 through the restrictor 64, and the discharge pressure P2 generated in the second discharge passage 22 is guided through the restrictor 65 to thereby discharge the discharge pressure P1. An average discharge pressure Pave obtained by averaging the pressures P1 and P2 is generated. The average discharge pressure Pave is also taken out from the average discharge pressure port 32.

  One end of the horsepower control springs 48 and 49 is connected to the spool 70, and the other end is linked to the swash plate 15. The spring length of the horsepower control spring 49 is formed shorter than the spring length of the horsepower control spring 48 so that the spring force of the horsepower control springs 48 and 49 increases stepwise according to the tilt angle of the swash plate 15 and the stroke of the spool 70. It has become.

  The regulator 40 has an original pressure guided from the original pressure passage 53 to the first control pressure passage 55 and an operating oil pressure (control pressure) Pc guided to the LS regulator 60 by discharging from the first control pressure passage 55 to the low pressure passage 59. Adjust.

  The original pressure passage 53 includes a first original pressure passage 51 and a second original pressure passage 52 that branch from the first discharge passage 21 and the second discharge passage 22, respectively, and the first original pressure passage 51 and the second original pressure passage. And a high-pressure selection valve 50 that selectively opens the higher one of the hydraulic oil pressures P1 and P2.

  Accordingly, the higher one of the hydraulic pressure P1 guided from the first discharge passage 21 to the first primary pressure passage 51 and the hydraulic pressure P2 guided from the second discharge passage 22 to the second primary pressure passage 52 is the higher pressure selection valve 50. And is guided to the regulator 40 and the small diameter actuator 47 through the original pressure passage 53.

  The regulator 40 adjusts the operating oil pressure Pc so that the signal pressure based on the average discharge pressure Pave and the spring force of the horsepower control springs 48 and 49 are balanced.

  A signal pressure passage 29 branched from the third discharge passage 23 is connected to the regulator 40, and the discharge pressure (second signal pressure) P3 of the first constant capacity pump 12 guided to the spool 70 by the signal pressure passage 29 is a spring force. Acts in the opposite direction. The second signal pressure P3 is also taken out from the second signal pressure port 39.

  As a result, when the load of the first constant displacement pump 12 that drives the swing motor increases, the discharge pressure P3 rises, and the spool 70 of the regulator 40 moves in the direction of switching to the position a, and the operating oil pressure Pc. Can be enhanced.

  Further, an external signal pressure passage 28 is connected to the regulator 40, and a horsepower control signal pressure Pi guided by the external signal pressure passage 28 acts on the spool 70 in the same direction as the spring force. As a result, when the horsepower control signal pressure Pi increases, the spool 70 of the regulator 40 moves in the direction of switching to the position b, and the working hydraulic pressure Pc is lowered.

  The LS regulator 60 is a 3-port 2-position switching valve and includes a spool (not shown) that moves between positions c and d. A signal pressure Pps generated on the upstream side of the control valve is guided to one end of the spool from the signal port 36 through the signal passage 43. A signal pressure Pls generated on the downstream side of the control valve is guided from the signal pressure port 37 through the signal passage 44 to the other end of the spool. Furthermore, the spring force of the LS spring 14 is applied to the other end of the spool. The spool moves to a position where the LS differential pressure (Pps-Pls) generated before and after the control valve and the spring force of the LS spring 14 acting on the other end are balanced, and switched to positions c and d.

  For example, when the load of each hydraulic cylinder or the like that drives the boom, arm, and bucket is large, the signal pressure (load pressure) Pls led to the signal pressure port 37 from the downstream side (load side) of the control valve increases. As a result, when the LS differential pressure (Pps−Pls) decreases, the spool is held at the position c by the spring force of the LS spring 14 as shown in FIG. At this position c, the first control pressure passage 55 connected to the regulator 40 and the second control pressure passage 56 connected to the actuator 16 are communicated, and the control pressure Pcg guided from the LS regulator 60 to the actuator 16 is the regulator. It becomes a value based on the value Pc adjusted by 40.

  On the other hand, when the load of each hydraulic cylinder or the like that drives the boom, arm, and bucket is small, the signal pressure (load pressure) Pls is low. As a result, when the LS differential pressure (Pps−Pls) increases, the spool moves in a direction to switch to the position d against the spring force of the LS spring 14. In this position d, the main pressure passage 54 branched from the second discharge passage 22 and the discharge pressure P2 is guided to the second control pressure passage 56 connected to the actuator 16, and the control pressure Pcg increases.

  Thus, the LS regulator 60 adjusts the control pressure Pcg guided to the actuator 16 so that the LS differential pressure and the spring force of the LS spring 14 are balanced. Thus, the discharge capacity of the pump 11 is controlled so that the LS differential pressure (Pps−Pls) becomes substantially constant even when the load on the hydraulic cylinder increases or decreases.

  A throttle 66 is interposed in the first control pressure passage 55, and a throttle 67 is interposed in the main pressure passage 54, so that fluctuations in the main pressure introduced to the LS regulator 60 are alleviated.

  A control pressure communication passage 69 that communicates the first control pressure passage 55 and the second control pressure passage 56 is provided. A throttle 18 and a check valve 17 are interposed in the control pressure communication passage 69.

  In a normal state where the control pressure Pcg in the second control pressure passage 56 is higher than the operating oil pressure Pc in the first control pressure passage 55, the check valve 17 is closed. When the control pressure Pcg drops below the operating oil pressure Pc by a predetermined value, the check valve 17 opens and the operating oil pressure Pc in the first control pressure passage 55 bypasses the LS regulator 60 through the second control pressure passage 56. Guided to the actuator 16.

  The pump control device 1 is provided with an adjustment mechanism that increases the discharge flow rate of the pump 11 as the pump rotation speed increases. This adjusting mechanism drives the spool 27 of the LS regulator 60 according to the throttle 27 interposed in the signal pressure passage 24 for guiding the hydraulic oil discharged from the second constant capacity pump 13 and the differential pressure across the throttle 27. And a control pressure actuator 90.

  The upstream pressure P 4 of the throttle 27 in the signal pressure passage 24 is guided to the control pressure actuator 90 through the upstream control pressure communication passage 94, and the downstream pressure P 5 of the throttle 27 is guided through the downstream control pressure communication passage 95.

  When the front-rear differential pressure (P4-P5) of the restrictor 27 increases as the pump rotational speed increases, the piston of the control pressure actuator 90 that receives this front-rear differential pressure causes the spool of the LS regulator 60 to open at the position c. Move in the direction of increasing. As a result, the control pressure Pcg guided from the LS regulator 60 to the actuator 16 decreases, and the discharge capacity of the pump 11 increases due to the operation of the actuator 16.

  Next, a specific configuration of the regulator 40 will be described.

  As shown in FIG. 2, the regulator 40 includes a cylindrical housing 100 having a spool housing hole 110 and a columnar spool 70 that is slidably housed in the spool housing hole 110. The housing 100 is attached to a casing (not shown) of the variable displacement pump 11.

  The spool 70 has a tip portion protruding from the opening end of the spool accommodation hole 110, and a spring receiver (not shown) is attached to the tip portion. Horsepower control springs 48 and 49 (see FIG. 1) are interposed between the spring receiver and a feedback pin (not shown) linked to the swash plate 15 of the variable displacement pump 11.

  A plug 140 is screwed onto the base end portion of the housing 100. The spool 70 is urged in the direction toward the plug 140 (leftward in FIG. 2) by the horsepower control springs 48 and 49, and the stroke of the spool 70 is restricted when the proximal end abuts against the plug 140.

  A back pressure chamber 130 is defined between the housing 100 and the proximal end portion of the spool 70 and the plug 140. The back pressure chamber 130 communicates with the inside (tank side) of the variable displacement pump 11 through a through hole (not shown).

  The spool 70 is formed with a shaft hole 79 that opens at the base end thereof and extends in the axial direction. A pin 96 is slidably accommodated in the shaft hole 79. The pin 96 is restricted from moving leftward in FIG. 2 when its proximal end abuts against the plug 140.

  The stepped cylindrical pin 96 includes a large-diameter pin portion 98 that contacts the plug 140, a small-diameter pin portion 97 that is thinner than the large-diameter pin portion 98, and a pin outer peripheral step portion 99 formed in the middle thereof. Have.

  Five ports 101 to 105 are formed in the housing 100. These ports 101 to 105 extend in the radial direction of the spool 70 and pass through the spool accommodation hole 110. The ports 101 to 105 communicate with the passages 55, 53, 63, 23, and 28 (see FIG. 1) described above via respective annular grooves formed on the outer periphery of the spool 70.

  The control pressure port 101 constitutes a first control pressure passage 55. In the control pressure port 101, an operation hydraulic pressure (control pressure) Pc that is guided to the actuator 16 through the LS regulator 60 is generated by the operation of the spool 70.

  The original pressure port 102 constitutes an original pressure passage 53. The higher one of the discharge pressures P1 and P2 of the first discharge passage 21 and the second discharge passage 22 is guided to the original pressure port 102.

  The driving pressure port 103 constitutes a discharge pressure signal passage 63. An average discharge pressure Pave obtained by averaging the discharge pressures P1 and P2 of the working fluid discharged to each discharge port of the variable displacement pump 11 is guided to the drive pressure port 103.

  The second signal pressure port 104 constitutes a signal pressure passage 29. The second signal pressure port 104 is supplied with hydraulic oil pressure P3 supplied from the first constant displacement pump 12 to the swing motor.

  The first signal pressure port 105 constitutes the external signal pressure passage 28. The first signal pressure port 105 is supplied with a horsepower control signal pressure Pi for switching the operation mode.

  A tank pressure port communication hole 71, a drive pressure port communication hole 72, and a second signal pressure port communication hole 73 are formed in the middle of the spool 70. These port communication holes 71 to 73 extend in the radial direction of the spool 70, and both ends of the port communication holes 71 to 73 open in annular grooves formed on the outer periphery of the spool 70.

  A tank pressure port 74 is formed at the tip of the spool 70. The tank pressure port 74 extends in the axial direction of the spool 70, and one end thereof opens to the tank pressure port communication hole 71, and the other end opens to the tip of the spool 70. ). The tank pressure port 74 discharges the hydraulic pressure Pc into the case.

  Six land portions 81 to 86 projecting in an annular shape are formed on the outer periphery of the spool 70. The outer periphery of each of the land portions 81 to 86 is in sliding contact with the inner periphery of the spool accommodation hole 110.

  When the spool 70 moves in the axial direction and switches between the position a and the position b, the land portions 81 and 82 selectively open the tank pressure port communication hole 71 and the original pressure port 102 with respect to the spool accommodation hole 110. The hydraulic pressure (control pressure) Pc generated at the control pressure port 101 is adjusted.

  In a state where the spool 70 is between the position a and the position b, the land portion 81 blocks between the tank pressure port communication hole 71 and the control pressure port 101, and the land portion 82 includes the original pressure port 102 and the control pressure port 101. Between the two.

  In the state where the spool 70 is at the position b as shown in FIG. 2, the tank pressure port communication hole 71 and the control pressure port 101 communicate with each other, and the operating oil pressure Pc is discharged into the case and decreases. At this time, the land portion 82 blocks between the source pressure port 102 and the control pressure port 101.

  When the spool 70 moves rightward in FIG. 2 and switches to the position a, the main pressure port 102 and the control pressure port 101 communicate with each other, and the higher pressure of the discharge pressures P1 and P2 guided to the main pressure passage 53 is obtained. Is guided to the LS regulator 60 through the first control pressure passage 55, and the hydraulic pressure Pc increases. At this time, the land portion 81 blocks between the tank pressure port communication hole 71 and the control pressure port 101.

  The drive pressure port communication hole 72 and the drive pressure port 103 are always in communication regardless of the position of the spool 70. The land portion 83 blocks communication between the drive pressure port 103 and the original pressure port 102, and the land portion 84 blocks between the drive pressure port 103 and the second signal pressure port 104.

  In the middle of the drive pressure port communication hole 72, the tip 95A of the pin 96 protruding from the opening end of the shaft hole 79 faces. A portion of the inner wall surface of the driving pressure port communication hole 72 facing the tip 95A of the pin 96 constitutes the driving pressure receiving surface 72A. The driving pressure receiving surface 72 </ b> A has a receiving surface area corresponding to the cross-sectional area of the small diameter pin portion 97. The spool 70 is moved in the right direction in FIG. 2 by the average discharge pressure Pave received by the driving pressure receiving surface 72A, and the tip end portion of the spool 70 is pushed out of the housing 100.

  A recess 89 is formed in a portion of the inner wall surface of the drive pressure port communication hole 72 that faces the tip 95A of the pin 96. The recess 89 is formed coaxially with the shaft hole 79 so that the tip 95 </ b> A of the pin 96 does not interfere with the spool 70.

  A second signal pressure chamber 121 is defined between the shaft hole 79 and the pin 96. The second signal pressure chamber 121, the second signal pressure port communication hole 73, and the second signal pressure port 104 are always in communication regardless of the position of the spool 70. The land portion 85 blocks communication between the second signal pressure port 104 and the first signal pressure port 105.

  The pin outer peripheral step portion 99 of the pin 96 faces the second signal pressure chamber 121, and the portion of the inner surface of the second signal pressure port communication hole 73 that faces the pin outer peripheral step portion 99 of the pin 96 defines the driving pressure receiving surface 72 </ b> A. Configure. The second signal pressure receiving surface 73 </ b> A has a receiving surface area corresponding to a cross-sectional area difference between the small diameter pin portion 97 and the large diameter pin portion 98. The spool 70 moves to the right in FIG. 2 by the second signal pressure P3 received by the second signal pressure receiving surface 73A, and the tip of the spool 70 is pushed out of the housing 100.

  The spool 70 has a small-diameter spool portion 77, a large-diameter spool portion 76 that is thicker than the small-diameter spool portion 77, and an outer peripheral step portion 78 formed in the middle thereof.

  The spool housing hole 110 of the housing 100 includes a small diameter hole portion 111 into which the small diameter spool portion 77 is inserted, and a large diameter hole portion 112 into which the large diameter spool portion 76 is inserted.

  A first signal pressure chamber 120 is defined between the large-diameter hole 112 of the housing 100 and the spool 70. The first signal pressure chamber 120 and the first signal pressure port 105 are always in communication regardless of the position of the spool 70. The land portion 86 blocks communication between the first signal pressure chamber 120 and the back pressure chamber 130.

  The outer peripheral step 78 of the spool 70 faces the first signal pressure chamber 120, and a portion corresponding to the cross-sectional area difference between the small diameter spool portion 77 and the large diameter spool portion 76 constitutes the first signal pressure receiving surface 78A. The spool 70 moves leftward in FIG. 2 by the horsepower control signal pressure Pi received on the first signal pressure receiving surface 78A.

  Next, the operation of the regulator 40 will be described.

  When the force due to the average discharge pressure Pave received on the driving pressure receiving surface 72A of the spool 70 is smaller than the spring force of the horsepower control springs 48 and 49, the spool 70 is in the position b as shown in FIG. At the position b, the hydraulic pressure Pc is discharged from the control pressure port 101 to the tank pressure port 74 and decreases.

  On the other hand, when the force due to the average discharge pressure Pave applied to the driving pressure receiving surface 72A of the spool 70 becomes larger than the spring force of the horsepower control springs 48 and 49, the direction in which the spool 70 switches to the position a (rightward in FIG. 2). ) In the position a, the higher one of the operating oil pressures P1 and P2 is guided from the original pressure port 102 to the control pressure port 101, and the operating oil pressure Pc of the control pressure port 101 increases.

  Thus, the regulator 40 adjusts the operating oil pressure Pc so that the signal pressure based on the average discharge pressure Pave and the spring force of the horsepower control springs 48 and 49 are balanced. Even if the rotational speed of the pump 11 increases, when the average discharge pressure Pave increases, the control pressure Pcg guided through the LS regulator 60 is increased by the operation of the regulator 40, and the discharge capacity of the pump 11 decreases.

  The control system (not shown) of the hydraulic excavator includes a high load mode (normal operation mode) in which the engine 10 is operated at a predetermined rated rotational speed and a low load in which the engine 10 is operated at a rotational speed lower than the rated rotational speed. The mode (fuel saving operation mode) can be switched. The horsepower control signal pressure Pi is increased in the high load mode while being switched low in the low load mode. This mode switching is performed by a driver's switch operation or the like, but is not limited thereto, and may be configured to be performed automatically according to the operation or stop of an air conditioner (air conditioner) or the like.

  When the operation is switched from the high load mode to the low load mode, the regulator 40 reduces the force by the horsepower control signal pressure Pi received on the first signal pressure receiving surface 78A as the horsepower control signal pressure Pi is switched low. The spool 70 moves in the direction (right direction in FIG. 2) in which the spool 70 is switched to the position a. As a result, the hydraulic pressure Pc of the control pressure port 101 is increased, and the discharge capacity of the pump 11 is reduced.

  Further, when the swing motor rotates the cab, the hydraulic pressure P3 supplied from the first constant capacity pump 12 to the swing motor increases. At this time, in the regulator 40, when the second signal pressure P3 received on the second signal pressure receiving surface 73A is increased, the spool 70 moves in the direction of switching to the position a (rightward in FIG. 2). As a result, the operating pressure Pc of the control pressure port 101 is increased, and the discharge capacity of the pump 11 is reduced.

  FIG. 3 is a characteristic diagram showing the relationship between the signal pressures Pave, Pi, P3 and the discharge capacity of the pump 11. The discharge capacity of the pump 11 decreases as the average discharge pressure Pave increases due to the operation of the regulator 40. As a result, the work rate (horsepower) of the pump 11 is adjusted to be substantially constant, and the operation is smoothly performed even if the rotational speed of the engine 10 increases or decreases. In the low load mode, the discharge capacity of the pump 11 is reduced by the operation of the regulator 40 by the horsepower control signal pressure Pi compared to the high load mode. Thereby, the work rate of the pump 11 is lowered, and the load on the engine 10 that drives the pump 11 is reduced. When the swing motor is operated, the discharge capacity of the pump 11 is reduced by the operation of the regulator 40 by the second signal pressure P3 from the first constant capacity pump 12. Thereby, the work rate of the pump 11 is further reduced, and the load on the engine 10 that drives the pump 11 is reduced.

  According to the above embodiment, there exists an effect shown below.

  [1] The regulator 40 includes a driving pressure port 103 to which an average discharge pressure Pave obtained by averaging discharge pressures P1 and P2 of the working fluid discharged from the plurality of discharge ports is guided, and a working fluid discharged from the plurality of discharge ports. By moving by receiving the original pressure port 102 through which the highest high-pressure side discharge pressures P1 and P2 are guided, the signal pressure port 105 through which the horsepower control signal pressure Pi is guided, and the average discharge pressure Pave and the horsepower control signal pressure Pi. A spool 70 that adjusts the control pressure Pc using the high-pressure side discharge pressures P1 and P2 as original pressures, and a drive pressure receiving surface 72A that receives the average discharge pressure Pave is formed inside the spool 70. A signal pressure receiving surface 78A for receiving the horsepower control signal pressure Pi is formed.

  Thus, the spool 70 of the regulator 40 has an average discharge pressure Pave obtained by averaging the discharge pressures P1 and P2 of the working fluid discharged from the plurality of discharge ports of the pump 11 on the drive pressure receiving surface 72A formed inside the spool 70. The control pressure Pc guided to the actuator 16 is adjusted using the highest discharge pressures P1 and P2 among the discharge pressures of the working fluid discharged from the plurality of discharge ports as the original pressure. Further, the spool 70 also adjusts the control pressure Pc by receiving and moving the horsepower control signal pressure Pi on the signal pressure receiving surface 78A of the outer peripheral step 78. In this way, the pump control device 1 has the structure having the driving pressure receiving surface 72A inside the spool 70, and does not increase the size of the spool 70, so that the power of the pump 11 can be reduced by using the regulator 40 having a simple structure. The discharge pressures P1 and P2 and the horsepower control signal pressure Pi can be controlled.

  As a comparative example, it is conceivable to use a regulator in which a plurality of outer circumferential step portions are formed on the spool and a driving pressure receiving surface that receives the discharge pressures P1 and P2 is provided on each outer circumferential step portion. As another comparative example, it is conceivable to use a regulator in which a plurality of pin members interlocking with the spool are provided and each pin member is provided with a driving pressure receiving surface that receives the discharge pressures P1 and P2. In contrast to these comparative examples, the spool 70 is provided with a driving pressure receiving surface 72A that receives an average discharge pressure Pave obtained by averaging the discharge pressures P1 and P2, and thus has a plurality of outer peripheral step portions that receive the discharge pressures P1 and P2. It is not necessary to form the film, and the increase in size can be suppressed. Further, the regulator 40 does not need to be provided with a plurality of pin members interlocked with the spool 70, and can realize a simple structure.

  [2] The regulator 40 includes a drive pressure port communication hole 72 communicating with the drive pressure port 103 formed inside the spool 70, and a shaft hole 79 formed inside the spool 70 and connected to the drive pressure port communication hole 72. And a pin 96 that is slidably inserted into the shaft hole 79, and a portion of the inner wall surface of the drive pressure port communication hole 72 that faces the pin 96 constitutes the drive pressure receiving surface 72A.

  As a result, the pin 96 is accommodated inside the spool 70 and the driving pressure receiving surface 72A is provided so as to face the pin 96, so that the regulator 40 is large in the axial direction of the spool 70 by providing the driving pressure receiving surface 72A. Can be suppressed.

  [3] The regulator 40 communicates with the second signal pressure port 104 through which the second signal pressure P3 different from the horsepower control signal pressure Pi is guided, and the shaft hole 79 and the second signal pressure port 104 formed in the spool 70. A second signal pressure port communication hole 73. A pin outer peripheral step 99 is formed in the middle of the pin 96, and faces the pin outer peripheral step 99 on the inner wall surface of the second signal pressure port communication hole 73. The portion constitutes the second signal pressure receiving surface 73A that receives the second signal pressure P3.

  As a result, the second signal pressure receiving surface 73A that receives the second signal pressure P3 is provided to face the pin outer peripheral step portion 99 of the pin 96, so that the regulator 40 can be connected to the shaft of the spool 70 by providing the second signal pressure receiving surface 73A. Increase in size in the direction can be suppressed.

  [4] High load mode in which the horsepower control signal pressure Pi received at the outer peripheral step 78 of the spool 70 increases and the spool 70 moves in a direction to increase the discharge capacity of the pump 11, and the horsepower received by the outer peripheral step 78 of the spool 70 The control signal pressure Pi is decreased and the spool 70 is switched to the low load mode in which the spool 70 moves in the direction of decreasing the discharge capacity of the pump 11.

  As a result, the spool 70 is moved by the horsepower control signal pressure Pi that decreases as the high load mode is switched to the low load mode, and the discharge capacity of the pump 11 is reduced. Since the horsepower control signal pressure Pi decreases in the low load mode, the driving load of the second constant capacity pump 12 is reduced, and the energy consumption of the pump control device 1 is reduced.

  The embodiment of the present invention has been described above, but the above embodiment only shows a part of application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. is not.

  The pump control device of the present invention can be used not only for a working machine such as a hydraulic excavator but also for a fluid pressure supply source provided in another machine or facility.

DESCRIPTION OF SYMBOLS 1 Pump control apparatus 11 Pump 16 Actuator 40 Regulator 70 Spool 72 Drive pressure port communication hole 72A Drive pressure receiving surface 73 Second signal pressure port communication hole 73A Second signal pressure receiving surface 78 Outer peripheral step part 78A Signal pressure receiving surface 79 Shaft hole 95 Pin 99 Pin peripheral step 102 Source pressure port 103 Drive pressure port 104 Second signal pressure port 105 Signal pressure port

Claims (4)

A pump control device that controls the discharge capacity of a pump that discharges working fluid from a plurality of discharge ports,
An actuator that changes the discharge capacity of the pump;
A regulator for adjusting a control pressure guided to the actuator,
The regulator is
A driving pressure port to which an average discharge pressure is derived by averaging the discharge pressures of the working fluid discharged from the plurality of discharge ports;
An original pressure port through which the highest high-pressure side discharge pressure is guided among the working fluid discharged from the plurality of discharge ports;
A signal pressure port through which the signal pressure is guided;
A spool that adjusts the control pressure using the high-pressure side discharge pressure as a source pressure by moving in response to the average discharge pressure and the signal pressure;
A driving pressure receiving surface that receives the average discharge pressure is formed inside the spool,
2. A pump control device according to claim 1, wherein a signal pressure receiving surface for receiving the signal pressure is formed on an outer peripheral step portion of the spool. The regulator is
A driving pressure port communication hole formed inside the spool and communicating with the driving pressure port;
A shaft hole formed inside the spool and connected to the drive pressure port communication hole;
A pin that is slidably inserted into the shaft hole;
2. The pump control device according to claim 1, wherein a portion of the inner wall surface of the driving pressure port communication hole facing the pin constitutes the driving pressure receiving surface. The regulator is
A second signal pressure port through which a second signal pressure different from the signal pressure is guided;
A second signal pressure port communication hole formed inside the spool and communicating with the shaft hole and the second signal pressure port;
In the middle of the pin, a pin outer peripheral step is formed,
The portion of the inner wall surface of the second signal pressure port communication hole facing the pin outer peripheral step portion constitutes a second signal pressure receiving surface that receives the second signal pressure P. Pump control device. A high load mode in which the signal pressure received by the outer peripheral step of the spool rises and the spool moves in a direction to increase the discharge capacity of the pump;
4. The low load mode in which the signal pressure received at the outer peripheral step portion of the spool is lowered and the spool moves in a direction to reduce the discharge capacity of the pump, is switched to the low load mode. The pump control apparatus described in one.

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