WO1998049450A1

WO1998049450A1 - Drive system for hydraulic motors

Info

Publication number: WO1998049450A1
Application number: PCT/JP1998/001921
Authority: WO
Inventors: Sadao Nunotani; Naoki Ishizaki
Original assignee: Komatsu Ltd.
Priority date: 1997-04-25
Filing date: 1998-04-24
Publication date: 1998-11-05
Also published as: JP3736657B2; JPH10299706A

Abstract

A drive system for hydraulic motors is provided with an operating valve (13) for supplying pressure oil discharged by a hydraulic pump (10) to a hydraulic motor (17) and for passing the pressure oil returning from the hydraulic motor to a regenerating circuit (23), and with a counterbalancing valve (30), provided between the hydraulic motor and the operating valve and having a neutral position which prevents the pressure oil returning from the hydraulic motor from flowing to the operating valve and a flow position to pass the returning pressure oil to the operating valve, so designed as to be switched to the flow position when the discharge pressure of the hydraulic pump surpasses a prescribed level and switched to the neutral position when the discharge pressure of the hydraulic pump is at or below the prescribed level, and prohibited, when switched to the flow position by the discharge pressure of the hydraulic pump, from being switched to the neutral position by the returning hydraulic oil, wherein said regenerating circuit is connected to a discharge path (11) of the hydraulic pump via a check valve (26). This enables the returning pressure oil from the hydraulic motor to be regenerated and reused.

Description

Description Hydraulic motor drive system Technical field

The present invention relates to a hydraulic motor drive system such as a hydraulic motor for a winch that rotationally drives a winch of a hydraulic crane and a hydraulic motor for traveling that rotationally drives a crawler belt of a hydraulic excavator. is there. Background art

A drive system shown in Fig. 1 is known as a system for driving a traveling hydraulic motor that rotationally drives a crawler belt of a hydraulic shovel. This drive system basically includes a hydraulic pump 1, an operation valve 2, and a counterbalance valve 3. Then, by switching the operation valve 2 from the neutral position a to the first position b, pressure oil is supplied to one port 5 of the hydraulic motor 4, and the discharge pressure of the hydraulic pump 1 exceeds a predetermined pressure. Then, the counterbalance valve 3 moves from the neutral position c to the first position d, and the return pressure oil of the other port 6 of the hydraulic motor 4 is moved to the first position d of the counterbalance valve 3. Then, the hydraulic fluid flows into the tank 7 through the first position b of the operation valve 2, and the hydraulic motor 4 is driven to rotate in the negative direction. Also, as described above, when the hydraulic shovel travels down a hill with the operating valve 2 in the first position b, the hydraulic motor 4 is rotated by an external force to perform a pumping operation. Pressure drops. When the discharge pressure of the hydraulic pump 1 falls below a predetermined pressure, the counterbalance valve 3 moves toward the neutral position c, and the other side of the hydraulic motor 4 The flow of the pressure oil discharged from the port 6 is stopped or throttled, thereby restricting the flow of the return pressure oil from the hydraulic motor 4 and braking the hydraulic motor 4.

When the operation valve 2 is in the second position e, the counterbalance valve 3 is switched to the second position f, and operates as described above.

The drive system of the hydraulic motor for the winch that rotationally drives the winch of the hydraulic crank has the same configuration and operation as the drive system shown in FIG. 1 described above.

In this way, the hydraulic motor drive system for the hydraulic excavator traveling and the hydraulic motor for the winch of the hydraulic crane are mounted between the operation valve 2 and the hydraulic motor 4. A brake valve 3 is provided, and when the hydraulic motor 4 is rotated by an external force, the counterbalance valve 3 is moved toward the neutral position c so that a braking force is applied to the hydraulic motor 4. Configuration.

This prevents the hydraulic shovel from rolling over when traveling downhill and the load suddenly drops when the load is lowered by the hydraulic crane. You can prevent it from falling.

However, since the above-described drive system flows the return pressure oil from the hydraulic motor 4 to the tank 7, the return pressure oil is wasted. On the other hand, as a drive system that expands and contracts the boom cylinder of the hydraulic shovel, when the return pressure oil from the compression chamber of the boom cylinder is higher than the discharge pressure of the hydraulic pump, There is known a drive system having a regenerative function in which return pressure oil flows into a discharge side of a hydraulic pump and supplies the return pressure oil to an extension chamber of a boom cylinder.

Therefore, the drive system with the regenerative function described above is hydraulically operated. It can be applied to hydraulic motors for running vehicles and winches for hydraulic crane.

For example, as shown in Fig. 1, a throttle 9a is provided in the drain circuit 7a, and the upstream side of the throttle 9a is connected to the pump discharge path 1a via the check valve 9b, and the return oil is It is conceivable that pressure is generated to regenerate into the pump discharge path 1a.

As described above, in order to generate back pressure in the return oil and regenerate it to the pump discharge path 1a, the pressure of the return oil must be higher than the pump discharge pressure. When the valve 3 is in the neutral position c or the opposite position, the oil returns to the drain circuit 7a and the oil stops flowing.

For example, the operating valve 2 is set to the first position b to supply pressure oil to one port 5 of the hydraulic motor 4, and the counterbalance valve 3 is set to the first position d by the pressure of the first pressure receiving portion 3a. When the return oil pressure is higher than the pump discharge pressure while the hydraulic oil at the other port 6 of the hydraulic motor 4 is flowing to the tank 7 and the counterbalance valve is Since the pressure of the second pressure receiving portion 3b of FIG. 3 becomes higher than the pressure of the first pressure receiving portion 3a, the counter balance valve 3 becomes the neutral position c or the second position f. Return to a and oil stops flowing.

Therefore, an object of the present invention is to provide a hydraulic motor drive system that can solve the above-described problem. Disclosure of the invention

A first aspect of the hydraulic motor drive system according to the present invention for achieving the above object is as follows. An operation valve for supplying hydraulic pressure discharged from the hydraulic pump to the hydraulic motor, and for returning hydraulic oil from the hydraulic motor to the regenerative circuit;

A neutral position provided between the hydraulic motor and the operation valve, wherein a return pressure oil from the hydraulic motor does not flow through the operation valve, and a flow position through which the return pressure oil flows through the operation valve; The hydraulic pump is switched to a circulation position when the discharge pressure of the hydraulic pump exceeds a predetermined pressure, and is switched to a neutral position when the discharge pressure oil of the hydraulic pump is equal to or lower than a predetermined pressure. A counter balance valve that is prohibited from switching to the neutral position by return pressure oil when the circulation position is reached by the discharge pressure,

A hydraulic motor drive system, wherein the regenerative circuit is connected to a discharge path of the hydraulic pump via a check valve.

According to this configuration, the operating valve is switched to supply the discharge pressure oil of the hydraulic pump to one port of the hydraulic motor, and when the discharge pressure becomes high, the counterbalance valve is placed in the circulation position and the hydraulic motor is turned off. Return pressure oil flows to the tank via the counterbalance valve, operating valve, and regenerative circuit. At the same time, the counterbalance valve does not operate to the neutral position due to the pressure of the return pressure oil.

When the hydraulic motor is rotated by an external force in the state described above, the discharge pressure of the hydraulic pump decreases. When the discharge pressure of the hydraulic pump becomes lower than the pressure of the return pressure oil from the hydraulic motor, it flows into the discharge path of the hydraulic pump 10 from the check valve.

Therefore, the return pressure oil from the hydraulic motor can be regenerated and reused in the discharge path of the hydraulic pump.

In the first embodiment, It is preferable that the regenerative circuit be provided with a back pressure valve which is brought into the throttle communication position by a spring force and becomes the communication position when the discharge pressure of the hydraulic pump is higher than a set pressure.

According to this configuration,

When the discharge pressure of the hydraulic pump is higher than the set pressure by rotating the hydraulic motor with the discharge pressure oil of the hydraulic pump, the back pressure valve is in the communicating position. When the hydraulic motor is rotated by external force and the discharge pressure of the hydraulic pump is lower than the set pressure, the back pressure valve is in the throttle communication position.

Because of this, when the hydraulic motor is rotating with the hydraulic oil discharged from the hydraulic pump, the return hydraulic oil from the hydraulic motor flows smoothly to the tank and the pressure does not increase. In addition, the hydraulic motor can be rotated with a driving torque corresponding to the pressure of the discharge pressure oil of the hydraulic pump. Also, when the hydraulic motor is rotated by an external force, the pressure of the return pressure oil flowing in the regenerative circuit increases, and the return pressure oil flows into the discharge path of the hydraulic pump.

In the above configuration,

The counterbalance valve is held at a neutral position by a spring force, and when the discharge pressure of a hydraulic pump supplied to one of the pressure receiving parts exceeds a predetermined pressure, the counterbalance valve becomes one of the circulation positions and the other becomes the circulation position. If the discharge pressure of the hydraulic pump supplied to the pressure receiving section exceeds a predetermined pressure, it will be the other circulation position,

It is preferable to provide a pair of switching valves that are interlocked with the counterbalance valve and communicate the other or one pressure receiving portion to the tank by being at one or the other flow position.

A second aspect of the present invention provides The discharge pressure oil of the hydraulic pump is supplied and controlled to the left and right hydraulic motors via the left and right pressure compensation valves and the left and right operation valves, respectively.

A neutral position between the left and right operation valves and the left and right hydraulic motors, where the return pressure oil from the hydraulic motor does not flow to the operation valves, and a flow in which the return pressure oil flows to the operation valves. The hydraulic pump is switched to the circulation position when the discharge pressure of the hydraulic pump exceeds a predetermined pressure, and is switched to the neutral position when the discharge pressure oil of the hydraulic pump is equal to or lower than a predetermined pressure. Left and right counterbalance valves are provided, which are prevented from switching to the neutral position by return pressure oil by being returned to the circulation position by the discharge pressure of the hydraulic pump,

The return pressure oil from the left and right hydraulic motors respectively communicates with the left and right regenerative circuits flowing out of the left and right operation valves by the pressure of the first pressure receiving portion and the throttle communication position by the pressure of the second pressure receiving portion. Left and right back pressure valves

The first pressure receiving portions of the left and right back pressure valves are respectively connected to the output sides of the left and right pressure compensating valves,

The left and right pressure compensating valves are respectively formed with a first port and a second port which are shut off when the opening area is small and communicate with each other when the opening area is large,

The first ports of the left and right pressure compensating valves communicate with the second ports of the left and right back pressure valves, respectively, and the first ports of the left and right pressure compensating valves communicate with each other,

This is a hydraulic motor drive system in which second ports of the left and right pressure compensating valves are respectively connected to left and right load pressure introduction paths.

According to this configuration, The return oil of the driven hydraulic motor is regenerated during left-right turning, and excess hydraulic oil can be supplied to the driven hydraulic motor by that amount, so that a decrease in vehicle speed can be reduced.

Also, when descending, the opening area of each pressure compensating valve is small and the load pressure does not act on the second pressure receiving part of the back pressure valve, so that the back pressure valve is in the communicating position, and the return pressure oil of the left and right hydraulic motors is Not regenerated.

As a result, the hydraulic pressure discharged from the hydraulic pump is supplied to the left and right hydraulic motors when descending a slope, so that the heat balance is improved. BRIEF DESCRIPTION OF THE FIGURES

The invention will be better understood from the following detailed description and the accompanying drawings illustrating an embodiment of the invention. The embodiments shown in the accompanying drawings are not intended to specify the invention, but merely to facilitate explanation and understanding.

In the figure,

Fig. 1 is a circuit diagram of a conventional hydraulic motor drive system. FIG. 2 is a circuit diagram of a hydraulic motor drive system according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a specific structure of the operation valve, the back pressure valve, the check valve, and the pressure compensating valve according to the first embodiment.

FIG. 4 is a cross-sectional view showing a specific structure of the counterbalance valve according to the first embodiment.

FIG. 5 is a traveling hydraulic circuit diagram showing the second embodiment of the present invention.

FIG. 6 shows the operation valve, the back pressure valve, the check valve, and the pressure of the second embodiment. It is sectional drawing which shows the specific structure of a force compensating valve.

FIG. 7 is a traveling hydraulic circuit diagram showing the third embodiment of the present invention.

FIG. 8 is a cross-sectional view showing a specific structure of the operation valve, the back pressure valve, the check valve, and the pressure compensating valve according to the third embodiment. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a drive system of a hydraulic motor according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

First, a first embodiment will be described.

As shown in FIG. 2, the discharge path 11 of the hydraulic pump 10 is connected to the pump port 14 of the operation valve 13 via the pressure compensating valve 12. The first actuator port 15 of the operation valve 13 is connected to one port 18 of the hydraulic motor 17 via the first main circuit 16. The second port 19 of the operation valve 13 is connected to the other port 21 of the hydraulic motor 17 via the second main circuit 20.

The regenerative port 22 of the operation valve 13 communicates with the tank 24 in the regenerative circuit 23. The regenerative circuit 23 is provided with a back pressure valve 25. The upstream side of the back pressure valve 25 in the regenerative circuit 23 is connected to the output side of the pressure compensating valve 12 in the discharge path 11 of the hydraulic pump 10 by a check valve 26. The tank port 27 of the operation valve 13 is connected to the tank 24.

A counterbalance valve 30 provided between the first main circuit 16 and the second main circuit 20 is held at a neutral position A by a spring 31 and a first valve acting on the first pressure receiving portion 32 is actuated. The pressure of the main circuit 16 acts on the second pressure receiving section 3 3 When the pressure becomes higher than the switching pressure of the second circuit 20 by more than the switching pressure, the switching to the first position B is performed, and the pressure of the second main circuit 20 acting on the second pressure receiving part 33 is changed to the first pressure receiving part. When the pressure becomes higher than the switching pressure of the first main circuit 16 acting on 32 by more than the switching pressure, switching to the second position C is performed.

The first pressure receiving portion 32 of the counterbalance valve 30 is connected to the operation valve 13 closer to the operation valve 13 than the check valve 35 in the first main circuit 16 in the first circuit 34. The first circuit 34 has an aperture 36. An intermediate portion between the throttle 36 and the first pressure receiving portion 32 of the first circuit 34 is communicated with and blocked from the tank by the first switching valve 37.

The first switching valve 37 is pushed toward a shut-off position by a spring 38 and pushed toward a communication position by a counterbalance valve 30. When the power center balance valve 30 is in the neutral position A or the first position B, the first switching valve 37 is in the shut-off position. When the counterbalance valve 30 is at the second position C, the first switching valve 37 is at the communication position.

The second pressure receiving portion 33 of the counterbalance valve 30 is connected to the operation valve 13 closer to the operation valve 13 than the check valve 35 in the second main circuit 20 in the second circuit 39. The second circuit 39 has an aperture 40. An intermediate portion between the throttle 40 and the second pressure receiving portion 33 of the second circuit 39 is communicated with the tank by the second switching valve 41 and is shut off.

The second switching valve 41 is pushed toward the shut-off position by the spring 42 and pushed toward the communication position by the counterbalance valve 30. When the power counterbalance valve 30 is in the neutral position A or the second position C, the second switching valve 41 is in the shut-off position. When the counterbalance valve 30 is in the first position B, the second switching valve 41 is in the communicating position.

The back pressure valve 25 is pushed to the throttle communication position by a spring 43, It is pushed to the communicating position by the discharge pressure of the hydraulic pump 10 acting on 4 4. In the back pressure valve 25, the discharge pressure of the hydraulic pump 10 causes the pressure to rise due to the passing pressure loss of the operation valve 13 and switches the counter balance valve 30 to the first position B or the second position C. The communication position is established when the value becomes equal to or greater than the sum of the switching pressure.

The pressure compensating valve 12 is a conventionally known pressure compensating valve composed of a load tick valve 45 and a pressure reducing valve 46. The higher pressure of the first main circuit 16 and the second main circuit 20 is detected by the shuttle valve 47. The pressure detected by the shuttle valve 47 acts on the pressure compensating valve 12 (reducing valve 46) as its own load pressure. When driving a plurality of actuators, the output side of the pressure reducing valve 46 of all the pressure compensating valves 12 is connected to the load pressure detecting circuit 48 so that the highest load pressure is detected. is there.

The hydraulic pump 10 is of a variable displacement type, and its displacement is controlled by a displacement control valve 49 and a displacement control cylinder 50, as conventionally known, between the load pressure of the load pressure detection circuit 48 and the pump discharge pressure. The differential pressure is controlled to be constant. As a result, when the operation valve 13 is in the neutral position D, its opening area is zero, so that the capacity of the hydraulic pump 10 is minimized, and the operation valve 13 is moved to the first position E or the second position F. Then, the capacity of the hydraulic pump 10 increases according to the opening area.

Next, the operation of the first embodiment will be described. Since the pressure compensating valve 12 functions when a plurality of actuators are simultaneously operated, the operation thereof is omitted.

When the operation valve 13 is in the neutral position D, the pump port 14 is shut off, and the first and second operation ports 15 and 19 and the regenerative port are turned off. 22 communicates with tank 24 via tank port 27.

As a result, the tank pressure in the first and second main circuits 16 and 20 becomes the tank pressure, so that the counter balance valve 30 is in the neutral position A. Since the opening area of the operation valve 13 is zero, the capacity of the hydraulic pump 10 becomes the minimum and the discharge pressure thereof becomes the lowest. As a result, the back pressure valve 25 is at the throttle communication position.

When the operating valve 13 is in the first position E, the pump port 14 and the first actuator port 15 communicate with each other, and the second actuator port 19 is connected to the regenerative port 19. To 22. As a result, the discharge pressure oil of the hydraulic pump 10 flows from the first main circuit 16 to one port 18 of the hydraulic motor 17, and the pressure oil of the second main circuit 20. Flows out to the tank 24 via the operation valve 13 and the back pressure valve 25.

When the discharge pressure of the hydraulic pump 10 becomes equal to or higher than (switching pressure of the counterbalance valve 30 + pressure of the passing pressure loss of the operation valve 13), the back pressure valve 25 communicates. As well as the counterbalance valve

30 is the first position B, and the second switching valve 41 is the communicating position. As a result, the hydraulic oil at the other port 21 of the hydraulic motor 17 is supplied with the counterbalance valve 30 at the first position B, the operation valve 13 at the first position, and the communication valve at the communication position. Flows smoothly through a certain back pressure valve 25 to tank 24.

Thus, the hydraulic motor 17 is driven to rotate in one direction by the discharge pressure oil of the hydraulic pump 10 supplied to one port 18.

At this point, if the hydraulic motor 17 is rotated by an external force in the above-described state, the hydraulic motor 17 performs a pumping action, so that the pressure of one port 18 decreases and the other port 2 1 discharges pressure oil. At this time, the discharge pressure of the hydraulic pump 10 decreases, and the back pressure valve 25 is throttled to the communication position. The return pressure oil from the hydraulic motor 17 is throttled by the back pressure valve 25 and flows out to the tank 24, so that the back pressure of the regenerative circuit 23 becomes higher than the pump discharge pressure. The pressure oil in the regenerative circuit 23 flows from the check valve 26 to the discharge path 11.

In this way, the return pressure oil from the hydraulic motor 17 flows into the discharge path 11 of the hydraulic pump 10 so that the pressure oil corresponding to the flow rate can be reused.

At this time, since the second pressure receiving portion 33 of the counterbalance valve 30 communicates with the tank by the second switching valve 41, the counterbalance valve 30 is in the neutral position by the pressure of the regenerative circuit 23. It cannot be A or the second position C.

When the operation valve 13 is at the second position F, the counterbalance valve 30 is at the second position C, and the first switching valve 37 is at the communication position. Thus, the return pressure oil from the hydraulic motor 17 flows into the discharge path 11 of the hydraulic pump 10 and can be reused.

Next, a specific structure of the first embodiment will be described. In this specific structure, a description will be given of a case where a port for detection is provided in the operation valve, instead of detecting the load pressure by the check valve as described above. Note that the same parts as those shown in Fig. 2 are indicated by the reference numerals shown in Fig. 2 in parentheses. As shown in FIG. 3, the spool port 61 of the main body 60 is provided with a pump port 62 (14), first and second ports 63, 64, and first and second actuators. One port 65, 66 (15, 19), 1st. 2nd regenerative port 67, 68 (22), 1st. 2nd tank port 69, 70 ( 2 7) is formed. Insert the spool 7 1 into the spool hole 6 1 It is inserted to make operation valve 13.

When the spool 71 is in the neutral position shown in the figure, the pump port 62 is shut off from the first and second ports 63, 64. The first actuator port 65, the first regenerating port 67, and the first tank port 69 communicate with each other. The second actuator port 66, the second regenerating port 68, and the second tank port 70 communicate with each other. The first port 63 and the second port 64 communicate with each other through a communication path 72 indicated by a dotted line.

When the spool 71 is slid to the left to the first position, the pump port 62 and the second port 64 communicate with each other, and the first port 63 is connected to the first actuator port 6. Since it communicates with 5, the pressurized oil that has flowed into the pump port 62 flows to the first actuator overnight port 65. The connection between the first work port 65, the first regenerating port 67 and the first tank port 69 is cut off. The second actuating port 66 and the second regenerating port 68 continue to communicate, and the connection between the second regenerating port 68 and the second tank port 70 is cut off. 2nd Actuator Port

The return pressure oil flowing into 66 flows into the second regenerating port 68.

When the spool 71 is slid rightward to the second position, the pump port 62 and the first port 63 communicate with each other, and the second port 64 is connected to the second actuator port. Since it communicates with 66, the pressure oil that has flowed into the pump port 62 flows into the second actuating port 66. Second work port 66, second regenerated port 68, and second tank port

It is shut off between 70. The first actuating port 65 and the first regenerating port 67 continue to communicate, and the first regenerating port 67 and the first tank port 69 are cut off. The return pressure oil that has flowed into the cut-out port 65 flows into the first regeneration port 67. The first and second regeneration ports 67 and 68 communicate with the first and second regeneration ports 73 and 74, respectively, so that the first regeneration port 73 and the second regeneration port 73 are connected to each other. G 74 communicates with a communication hole 75 shown by a dotted line. The first regeneration port 73 communicates with the pump port 62 via a check valve 76. The second regenerating port 74 communicates with the tank port 78 through a notch 77a of the back pressure valve spool 77 fitted in a spool hole 60a of the valve body 60. .

The back pressure valve spool 77 is held at a position shown in the drawing by a spring 79 and cuts off the second regenerating port 74 to communicate with a tank port 78 by a 77a. That is, it is the same as when the back pressure valve 25 in FIG. 2 is in the throttle communication position.

When the pressure of the pump port 62 becomes equal to or higher than the set pressure, the back pressure valve spool 77 is pressed by the pressure to move the second regenerating port 74 and the tank port 78 to the small diameter portion. It is the position where communication is performed at 7 7 b. In other words, this is the same as when the back pressure valve 25 in FIG. 2 is in the communicating position. The set pressure has a value not less than (switching pressure of the counterbalance valve 30 + pressure loss of the operation valve 13).

The check valve 76 is formed by inserting a port 81 into a sleeve 80 screwed into a hole 60b coaxial with the spool hole 60a, and The port 81 is pressed in the shut-off direction by the pressure of the spring 82 and the pump port 62, and communicates with the pressure of the first regeneration port 73 acting on the step 81a of the port 81. It is configured to be pushed in the direction. Thus, when the pressure of the second regeneration port 73 is higher than the pressure of the pump port 62, the second regeneration port 73 is communicated with the pump port 62. A spool 92 is inserted and inserted into a spool hole 60 c of the valve body 60 to communicate and shut off an inlet port 90 and an outlet port 91, thereby constituting a one-way valve 45. are doing . The pressure reducing valve 46 is formed by a screw 93 that is fitted in a hole 60 d coaxial with the spool hole 60 c and pushes the spool 92 in the communicating direction. The discharge pressure oil of the hydraulic pump 10 is supplied to the inlet port 90, and the outlet port 91 communicates with the pump port 62.

The piston 93 moves in a direction away from the spool 92 by the pressure of the first pressure receiving chamber 94, and moves in a direction to push the spool 92 by the pressure of the second pressure receiving chamber 95. Further, the first pressure receiving chamber 94 communicates with the second port 63, and the piston 93 receives its own load pressure.

Since the pressure compensating valve composed of the spool 92 and the piston 93 is conventionally known, a detailed description thereof will be omitted.

Therefore, when the spool 71 is set to the first position, the return pressure oil flowing into the second actuator port 66 is supplied from the second regeneration port 68 to the first and second regeneration ports. It flows into ports 73 and 74. When the discharge pressure of the hydraulic pump 10 is high, the back pressure valve spool 77 stakes in the spring 79 and moves to the left, and the return pressure oil of the second regeneration port 74 is applied to the tank port. Flow to 7-8. As a result, the back pressure of the first and second regeneration ports 73 and 74 is low.

When the hydraulic motor 17 is rotated by an external force and the discharge pressure of the hydraulic pump 10 is reduced, the back pressure valve spool 77 is brought to the position shown by the spring 79. The return pressure oil at the second regeneration port 74 flows to the tank port 78 at the notch 77a, so the back pressure increases. 1st grade port When the return pressure oil at 73 becomes higher than the pump discharge pressure, the return pressure oil flows into the pump port 62 from the check valve 76.

The same applies to the case where the spool 71 is at the second position.

Next, the specific structure of the counterbalance valve 30 will be described.

As shown in FIG. 4, the first * second main ports 102, 103 and the first and second return ports 100, 104 are provided in the spool holes 101 of the valve body 100, respectively. Form 105. The spool 106 is inserted into the spool hole 101, and the spool 106 is set to the neutral position by the left and right springs 107. When pressure oil flows into one pressure chamber 108 (first pressure receiving part 32), the spool 106 moves to the left and the second main port 103 and the second return port 1 0 5 communicates. When the pressure oil flows into the other pressure chamber 109 (second pressure receiving part 33), the spool 106 moves to the right and the first main port 102 and the first return port 110 4 communicates.

The first pressure chamber 108 communicates with the first main port 102 via a first oil hole 110 (34) and a fine hole 111 (36) drilled in the spool 106. ing. The second pressure chamber 109 communicates with the second main port 103 via a second oil hole 112 (39) and a hole 113 (40) drilled in the spool 106. I have.

Sleeves 114 are attached to both left and right sides of the valve body 100, respectively. A tank port 115 is formed around the outer periphery of the sleeve 114, and the tank port 115 is formed by a hole 114 through the sleeve 114. It communicates with port 1 17 on the inner circumference of. A piston 119 is fitted in the sleeve 114, and the piston 119 is pushed by the spring 120 toward the spool 106. Between the first pressure chamber 108 and port 117 or between the second pressure chamber 109 and port The connection between the two is blocked.

When the spool 106 moves to the left due to the pressure in the first pressure chamber 108, the piston 119 provided on the left side is pushed by the spool 106 to move the second pressure chamber 109. It communicates with tank port 1 15 at port 1 17 and hole 1 16. As a result, the second pressure chamber 109 communicates with the dunk from the tank port 115. In this way, the second switching valve 41 in FIG. 2 is constituted by the piston 119 and the like provided on the left side.

When the spool 106 moves to the right due to the pressure in the second pressure chamber 109, the piston 110 provided on the right side is pushed by the spool 106 to cause the first pressure chamber 108 to move. It communicates with tank port 1 15 at port 1 17 and hole 1 16. As a result, the first pressure chamber 108 communicates with the tank from the tank port 115. In this way, the first switching valve 37 in FIG. 2 is constituted by the pistons 119 and the like provided on the right side.

The hydraulic motor drive system shown in Fig. 2 is applied to a drive system that drives the left and right traveling hydraulic motors of a hydraulic shovel with a single hydraulic pump, as in the second embodiment shown in Fig. 5. By doing so, it is possible to prevent the traveling speed from decreasing when turning left and right.

The details are described below.

The left and right control valves 13 are set to the first position E, the left control valve 13 has a large metering opening area, and the right control valve 13 has a small mating opening area. When the left hydraulic motor 17 is the driving side and the right hydraulic motor 17 is the driven side and turns in the direction of arrow a, the right hydraulic motor 17 is in the braking state and is driven. Pressure PL 2 is counterbalun And the driving pressure PL 1 of the left hydraulic motor 17 becomes high corresponding to the running resistance and the turning resistance. Therefore, the inlet pressure P 1 of the left operating valve 13 Is higher than the inlet pressure P 2 of the right control valve 13. That is, the load pressure of the left hydraulic motor 17 becomes higher than the load pressure of the right hydraulic motor 17.

As a result, the pressure reducing valve 46 of the pressure compensating valve 12 on the driving side (left side) is pushed rightward by the load pressure PL 1, and the opening degree of the opening check valve 45 increases, and the driven The pressure compensating valve 12 on the right side (right side) is depressed to the left by the load pressure PL 1 on the driving side (right side) to push the check valve 45 to the closing side, and the load check is performed. The opening of the valve 45 becomes small. In general, since the turning resistance of a crawler type vehicle is large, the discharge pressure of the variable displacement hydraulic pump 10 increases, the constant horsepower control works, the displacement decreases, and the flow rate flowing into the hydraulic motor 17 on the drive side decreases. It decreases and the vehicle speed decreases.

On the other hand, in the present invention, the return oil of the right hydraulic motor 17 is boosted by the back pressure valve 25 and is regenerated to the discharge path 11. For this reason, only the flow rate regenerated in the discharge passage 11 is supplied to the left hydraulic motor 17, so that the decrease in vehicle speed is reduced.

Next, a specific structure of the second embodiment will be described.

As shown in FIG. 6, the operation valve 13 is the same as that of the first embodiment, and the first 'second regenerative ports 67, 68 are connected to one regenerative port through an oil passage 130. Connect to port 1 3 1. The regenerating port 13 1 communicates with and is shut off from the tank port 78 by the back pressure valve spool 77, and communicates with the tank port 78 via the notch 77 a.

Port on the shaft hole 13 of the back pressure valve spool 77 of the back pressure valve 25 13 3 is inserted, and this port 13 3 is pushed by the spring 13 4 to close the regeneration side port 13 5 and the pump side port 13 36. The port 133 is pushed in the closing direction by the pump pressure acting on the proximal end surface 133a on the spring chamber 133 side, and is communicated with the return pressure oil acting on the distal end surface 133b. Pushed in the direction. This constitutes the check valve 26.

The operations of the check valve 26 and the back pressure valve 25 are the same as those in the first embodiment.

The valve body 60 is provided with a suction valve 140 for communicating the first port 63 and the first tank port 69. The suction valve 140 pushes the valve 141 to the shut-off position with the port pressure (return oil) acting on the spring 144 and the spring chamber 144, and the port pressure becomes the tank pressure. When the pressure becomes lower, the valve 14 1 stakes in the spring 14 2 and moves in the opening direction.

Thus, when the pressure of the port of the hydraulic motor 17 becomes negative, oil is sucked by the suction valve 140, so that the cavitation can be prevented. Next, another example of the traveling hydraulic system will be described as a third embodiment.

As shown in FIG. 7, the back pressure valve 25 is pushed toward the communicating position by the spring 43 and the pressure of the first pressure receiving portion 150, and is moved to the throttle communication position by the pressure of the second pressure receiving portion 151. It is pushed toward.

The first pressure receiving section 150 is connected to the output side of the pressure compensating valve 12 so that the output pressure of the pressure compensating valve 12 acts. The second pressure receiving section 15 1 is connected to a first port 15 2 formed on a pressure reducing valve 46 of the pressure compensating valve 12. The second port 15 3 formed in the pressure reducing valve 46 is a load pressure introduction path. Connected to 1 5 4. This load pressure introduction path 154 is connected to the load pressure port 155 of the operation valve 13. The first port 152 formed in the pressure reducing valve 46 of the left and right pressure compensating valves 12 is in communication with the circuit 1556.

Between the first port 152 and the second port 153, when the opening area of the load check valve 45 is small (when the load pressure is low), the port is shut off. When the opening area of one click X-valve 45 is large (when the load pressure is high), it communicates.

Next, the operation of this embodiment will be described.

The left and right control valves 13 are in the first position E, the left control valve 13 has a large METAINE opening area, and the right control valve 13 has a small METAN opening area. When the left hydraulic motor 17 is driven and the right hydraulic motor 17 is driven, and the vehicle turns in the direction of arrow a, the right hydraulic motor 17 is in a braking state. The driving pressure PL 2 is the set pressure of the counterbalance valve 30, and the driving pressure PL 1 of the left hydraulic motor 17 is a high pressure corresponding to the running resistance and the turning resistance. The inlet pressure P 1 of the control valve 13 is higher than the inlet pressure P 2 of the right control valve 13. That is, the load pressure of the left hydraulic motor 17 becomes higher than the load pressure of the right hydraulic motor 17.

As a result, the pressure reducing valve 46 of the pressure compensating valve 12 on the driving side (left side) is pushed rightward by the load pressure PL i, so that the opening of the check valve 45 becomes large, and the driven side ( The pressure compensating valve 12 of the right side) and the pressure reducing valve 4 6 of the second side are pushed to the left by the load pressure PL 1 on the driving side (the right side), and the mouth check valve 45 is pushed to the closing side. The opening of 5 becomes smaller. The opening area of the load check valve 45 of the left pressure compensating valve 12 is large. Therefore, the first port 152 and the second port 153 of the pressure reducing valve 46 communicate with each other, and a high load pressure flows through the first port 152. As a result, a high load pressure acts on the second pressure receiving portion 15 1 of the left back pressure valve 25, but pressure compensation is applied to the first pressure receiving portion 150 of the back pressure valve 25. Since the output pressure of the valve 12 is acting, the back pressure valve 25 is in the communicating position.

At this time, the opening area of the load check valve 45 of the pressure compensating valve 12 on the right is small and the connection between the first port 152 and the second port 153 is shut off. ing. The left load pressure acts on the second pressure receiving portion 15 1 of the right back pressure valve 25, and the pressure is higher than the output pressure of the right pressure compensating valve 12 acting on the first pressure receiving portion 150. High, so the back pressure valve 24 is in the throttle communication position>

Therefore, similarly to the traveling hydraulic system shown in FIG. 5, the return oil of the right hydraulic motor 17 is boosted by the back pressure valve 25 and is regenerated to the output side of the right pressure compensating valve 12. As a result, the flow supplied from the right pressure compensating valve 12 to the right hydraulic motor 17 for the hydraulic oil discharged from the hydraulic pump 10 is reduced by the regenerated flow, so that the left Is supplied to the hydraulic motor 17, and as a result, the decrease in vehicle speed is reduced.

When the left and right control valves 13 are in the first position E and the vehicle is traveling straight with the left and right control valves 13 having the same mating opening area, the load pressure of the left and right hydraulic motors 17 becomes high. The opening area of the load check valves 45 of the left and right pressure compensating valves 12 becomes large, and the first ports 15 2 formed on the pressure reducing valves 46 of the left and right pressure compensating valves 12 become larger. The second ports 15 3 communicate with each other. Therefore, the vehicle travels straight with the load pressure of the left and right hydraulic motors 17 being the same.

In addition, when the vehicle descends on a straight road as described above, the load pressure of the left and right hydraulic motors 17 becomes low, and the opening area of the load check valves 45 of the left and right pressure compensating valves 12 is small. The connection between the first port 15 2 of 46 and the second port 15 3 is shut off.

As a result, the load pressure does not act on the second pressure receiving portions 15 1 of the left and right back pressure valves 25, so that the respective back pressure valves 25 are connected to each other by the springs 43.

Therefore, the return oil of the left and right hydraulic motors 17 flows out to the tank without being regenerated, and only the discharge pressure oil of the hydraulic pump 10 is supplied to the left and right hydraulic motors 17, so that the heat balance is maintained. Is improved.

In other words, since the return oil of the hydraulic motor 17 is high in temperature, if the return oil of the hydraulic motor 17 is regenerated when going down a hill in a straight traveling state, high-pressure oil is supplied to the hydraulic motor 17 and furthermore. The return oil has a high temperature, and since high-temperature pressurized oil is supplied to the hydraulic motor 17 to repeat this, the heat balance is deteriorated, but this embodiment does not have this.

The specific structure of the aforementioned operating valve 13, pressure compensating valve 12, back pressure valve 25, and check valve 26 will be described with reference to FIG.

The back pressure valve spool 77 is set to the communication position by the spring 79, and the regenerative port 13 1 is connected to the tank port 78. The back pressure valve spool 77 has an oil hole 160 communicating the pump port 62 with the spring chamber 79a (first pressure receiving portion 150). A pressure chamber 16 1 (second pressure receiving section 15 1) is formed between the pressure chamber 16 and the valve body 60.

As a result, the back pressure valve spool 77 is pushed rightward by the pressure of the spring 79 and the spring chamber 79a to the communication position shown in the figure, and is moved leftward by the pressure of the pressure receiving chamber 161. To close the regenerative port 131, and cut off the regenerative port 131 to set the throttle communication position to communicate with 77a. Therefore, the back pressure valve 25 is the same as the back pressure valve 25 shown in FIG.

An auxiliary port 162 is formed in the pressure reducing valve 46, and a slit 163 that connects the first pressure receiving chamber 94 and the auxiliary port 162 is formed in the piston 93. The auxiliary port 16 2 communicates with the pressure receiving chamber 16 1 to become the first port 15 2 shown in FIG. 7, and the first pressure receiving chamber 94 becomes the second port 15 shown in FIG. It becomes 3.

When the opening area of the one-way check valve 45 is small, the screw 93 is shut off between the first pressure receiving portion 94 and the auxiliary port 162 at the position shown in FIG. This is the same as the state where the first port 152 and the second port 153 are shut off.

When the opening area of the load check valve 45 is large, the screw 93 moves to the right, and the first pressure receiving portion 94 and the auxiliary port 16 2 communicate with each other through the slit 16 3. In FIG. 7, the first port 152 and the second port 1553 are in communication.

The present invention has been described with reference to exemplary embodiments, or various changes, omissions, and additions may be made without departing from the spirit and scope of the present invention in connection with the disclosed embodiments. It is obvious to those skilled in the art. Therefore, the present invention is limited to the above embodiment. Rather, it is to be understood as covering the scope defined by the elements recited in the claims and their equivalents.

Claims

The scope of the claims

1. An operating valve that supplies the hydraulic oil discharged from the hydraulic pump to the hydraulic motor, and also allows the return hydraulic oil from the hydraulic motor to flow out to the regenerative circuit.

A neutral position that is provided between the hydraulic motor and the operating valve and has a neutral position in which return pressure oil from the hydraulic motor does not flow through the operation valve and a flow position in which the return pressure oil flows through the operation valve; When the discharge pressure of the hydraulic pump exceeds a predetermined pressure, the hydraulic pump is switched to the circulation position, and when the discharge pressure oil of the hydraulic pump is lower than the predetermined pressure, the switch is switched to the neutral position. A counterbalance valve that is prevented from switching to a neutral position by return pressure oil by being returned to the circulation position by the discharge pressure of the hydraulic pump,

A drive system for a hydraulic motor, wherein the regenerative circuit is connected to a discharge path of the hydraulic pump via a check valve.

2. The hydraulic motor according to claim 1, wherein the regenerative circuit is provided with a back pressure valve that is brought into a throttle communication position by a spring force and becomes a communication position when the discharge pressure of the hydraulic pump is equal to or higher than a set pressure. Drive system.

3. The counterbalance valve is held at the neutral position by a spring force, and when the discharge pressure of the hydraulic pump supplied to one of the pressure receiving portions exceeds a predetermined pressure, the counterbalance valve becomes one of the circulation positions. When the discharge pressure of the hydraulic pump supplied to the other pressure receiving section exceeds a predetermined pressure, the hydraulic pump is moved to the other flow position,

In conjunction with the counterbalance valve, the other or one pressure receiving portion communicates with the tank by being in the one or the other circulation position. The drive system for a hydraulic motor according to claim 1, further comprising a pair of switching valves that perform the switching.

4. Supply and control the discharge pressure oil of the hydraulic pump to the left and right hydraulic motors via the left and right pressure compensating valves and the left and right operating valves, respectively.

A neutral position between the left and right operation valves and the left and right hydraulic motors, in which return pressure oil from the hydraulic motor does not flow through the operation valves, and a distribution position in which the return pressure oil flows through the operation valves. The hydraulic pump is switched to a circulation position when the discharge pressure of the hydraulic pump exceeds a predetermined pressure, and is switched to a neutral position when the discharge pressure oil of the hydraulic pump is equal to or lower than a predetermined pressure. The return pressure oil is prohibited from switching to the neutral position by returning to the circulation position by the discharge pressure of the hydraulic pump.

The left and right regenerative circuits from the left and right hydraulic motors flow out of the left and right operation valves, respectively, into the left and right regenerative circuits. Provide left and right back pressure valves respectively,

The left and right pressure compensating valves are respectively formed with a first port and a second port that are shut off when the opening area is small and communicate with each other when the opening area is large,

The first ports of the left and right pressure compensating valves communicate with the second ports of the left and right back pressure valves, respectively, and the first ports of the left and right pressure compensating valves communicate with each other, A drive system for a hydraulic motor, wherein second ports of the left and right pressure compensating valves are respectively connected to left and right load pressure introduction paths.