JPH08135604A - Oil pressure valve device - Google Patents

Abstract

PURPOSE: To provide an oil pressure valve device capable of miniaturizing the device and reducing a manufacturing cost by realizing the commonness of the structure and arrangement of constant differential pressure type and variable differential pressure type pressure compensation valves. CONSTITUTION: When pressure, received by a first pressure receiving part 61b in an upward direction from an inflow port 10, is weaker than the sum of the highest load pressure received by a second pressure receiving part 61c in a downward direction and the spring force of a spring 32s, a pilot valve 61 is pressed downward to shut off a back pressure chamber 54 from a second passage 64. Pressure oil in the inflow port 10 is led in the back pressure chamber 54 via a first passage 62 to seat a main valve 60 to shut off the inflow port 10 from an outflow port 11. While when pressure, received by the first pressure receiving part 61b in an upward direction, is increased, the pilot valve 61 is moved upward to allow the second passage 65 to communicate with the back pressure chamber 54 to flow out pressure oil in the back pressure chamber 54 into the outflow port 11, but at that time, the inner pressure of the back pressure chamber 54 is lowered by pressure drop through an orifice 63 to move the main valve 60 upward to directly allow the inflow port 10 to communicate with the outflow port 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic valve device for controlling the drive of an actuator provided in a hydraulic machine such as a hydraulic excavator or a hydraulic crane.

[0002]

2. Description of the Related Art In the construction of a hydraulic circuit that guides pressure oil discharged from a pump to a plurality of actuators and controls the drive of these actuators, conventionally, the pump discharge pressure is set to be higher than the maximum load pressure of the actuator by a certain pressure. There is a so-called load sensing control for controlling the pump discharge capacity. In such a hydraulic circuit, a variable throttle portion and a pressure compensation valve for controlling the differential pressure across the variable throttle portion to a predetermined value are provided in each of the plurality of parallel pipelines into which the discharge pipeline of the variable displacement pump is branched. Is connected to the hydraulic valve device, and further to the downstream side of the hydraulic valve device, actuators that are driven and controlled by the hydraulic valve device are connected via a load conduit. Then, the load pressure of each actuator is guided to a load pressure signal line branched from the load line, and via a check valve provided in the load pressure signal line, one detection path for controlling the pump tilt angle. Be led to. In the above-mentioned configuration, the maximum load which is the maximum of the discharge pressure of the pump introduced through the signal line branched from the discharge line and the actuator load pressure of this hydraulic circuit detected in the detection line. The pressure and the pressure are respectively guided to the tilt control section of the pump, and the discharge capacity of the pump is controlled so that the discharge pressure is higher than the maximum load pressure by a constant pressure.

The following are examples of known techniques relating to such a hydraulic circuit. WO90 / 00683 In this known technique, a hydraulic pump, a plurality of actuators driven by pressure oil discharged from the hydraulic pump, and the actuators are provided corresponding to each of these actuators, and the hydraulic pump supplies the actuators. A plurality of directional control valves that control the flow of pressure oil and a plurality of pressures that are attached to these directional control valves and that control the differential pressure across the directional control valve, which is the differential pressure between the upstream pressure and the downstream pressure. The present invention provides a hydraulic circuit having a basic configuration that includes a compensating valve and is controlled such that the discharge pressure of the hydraulic pump is higher than the load pressure of the actuator by a constant pressure.

In this known technique, in the hydraulic circuit having the above-mentioned basic configuration, one of a plurality of pressure compensating valves constantly controls the differential pressure across the directional control valve to be a constant differential pressure type. A variable pressure control valve that controls the differential pressure across the directional control valve to match the differential pressure between the hydraulic pump discharge pressure and the actuator maximum load pressure. The pressure compensation valve is composed of a differential pressure type pressure compensating valve, which enables, for example, flow adjustment according to a combined operation of a hydraulic excavator.

[0005]

However, the above-mentioned known technique has the following problems. That is, when the basic configuration as exemplified in the above-mentioned known technique is applied to the combined drive of a plurality of actuators having different load pressures, the following two configurations are possible. (a) When a so-called constant differential pressure type pressure compensating valve that constantly controls the differential pressure across the directional control valve to be constant is provided as a pressure compensating valve in all of the directional control valves that control each actuator. When the total flow rate demanded by each actuator is greater than the flow rate discharged from the saturated state, the flow rate supplied to the low-voltage side actuator will remain constant, but the flow rate supplied to the high-voltage side actuator will decrease. To do. That is, the flow rate starts to become insufficient from the high load side of the plurality of actuators, and smooth actuator drive cannot be performed.

(B) As a pressure compensating valve, the differential pressure across the directional control valve is used as a pressure compensating valve for all the directional control valves for controlling the respective actuators. When a so-called variable differential pressure type pressure compensating valve that controls so as to match the pressure is provided In this case, when the sum of the required flow rate of each actuator increases and it is about to become saturated, the hydraulic pump Each variable differential pressure type pressure compensating valve controls the differential pressure across each directional control valve so as to be smaller than before depending on the degree of decrease in discharge pressure. As a result, the flow rate through each variable differential pressure type pressure compensating valve becomes smaller than before, and the occurrence of saturation is prevented, and the throttle opening area ratio of each variable throttle section is independent of the load pressure of each actuator. The flow rate can be distributed according to
That is, the flow rate discharged from the hydraulic pump is completely shunted to each of the high-pressure side actuator and the low-pressure side actuator, and the plurality of actuators can be smoothly driven. However, in this case, as a result of the flow distribution being prioritized for the high load, a new problem arises that the actuator speed on the low load side decreases. For example, in a hydraulic excavator, in the case of a work for loading earth and sand scooped into a bucket into a dump truck, a combined operation is performed in which a boom of a front working unit is raised and at the same time, an upper swing body provided in the front working unit is swung. At this time, in the hydraulic valve device using only the variable differential pressure type pressure compensating valve, the load sensing control of the pump and the pressure compensating control by the pressure compensating valve are performed on the basis of the swing load having a large inertia. Therefore, in the pipe line connected to the swing motor having a large inertia, the load pressure becomes high at the beginning of its activation, so that the flow rate diverted from the safety valve is discharged, and the hydraulic power for that amount is lost. In addition, this loss causes a decrease in boom raising speed. Also, in the pipeline connected to the boom cylinder that has a low load, pressure compensation control by the pressure compensation valve throttles the flow passage to generate heat, which causes energy loss. Invite. Further, at this time, generally, in order to protect the drive source of the pump, horsepower (=
Since the tilt control device for controlling the discharge pressure × the discharge flow rate to be less than or equal to a certain value is provided, the pump pressure rises to the relief pressure of the swing safety valve and the discharge flow rate of the pump decreases. Therefore, as the flow rate decreases, the boom raising speed further decreases. That is, due to the rapid acceleration of the revolving superstructure and the low speed of the boom, the operator cannot carry out smooth loading work.

Further, in the known technique, the actuator speed on the low load side does not decrease even during the complex operation as described above, and the above problem does not occur. That is, when performing a combined operation in which the boom of the front working unit is raised and the upper revolving structure provided in this front working unit is swung, a hydraulic valve device equipped with a constant pressure differential type pressure compensation valve on the boom cylinder side is used. By providing the hydraulic valve device having the variable differential pressure type pressure compensating valve on the swing motor side, it is possible to prevent the boom raising speed on the low load side from decreasing. However, in this known hydraulic valve device,
The constant differential pressure type pressure compensating valve and the variable differential pressure type pressure compensating valve are completely independent valves, and no consideration is given to the common use of these valves. Therefore, the structure of the entire hydraulic valve device provided with these cannot be made common, and the control signal pressure line related to the pressure compensating valve becomes complicated. Then, there is a problem that it becomes difficult to downsize the hydraulic valve device and reduce the manufacturing cost.

An object of the present invention is to provide a hydraulic valve device which can be downsized and reduced in manufacturing cost by making the structure and arrangement of the constant differential pressure type / variable differential pressure type pressure compensation valve common. Is.

[0009]

In order to achieve the above object, according to the present invention, the maximum load pressure of a variable displacement hydraulic pump and a plurality of actuators driven by pressure oil of this hydraulic pump is detected. Connected to the load pressure detection pipeline, the discharge pressure detection pipeline for detecting the discharge pressure of the hydraulic pump, the load pressure detection pipeline and the discharge pressure detection pipeline, the discharge pressure is a predetermined value from the maximum load pressure. A plurality of hydraulic circuits are provided in the hydraulic circuit including pump control means for controlling the discharge capacity of the hydraulic pump so that the displacement becomes higher, and each of the plurality of directional control valves includes a variable throttle and a front-back differential of the variable throttle. And a pressure compensator for controlling the pressure to a predetermined value.
In the hydraulic valve device for controlling the drive of two actuators, the pressure compensating unit includes a main valve that connects and disconnects an inflow port and an outflow port that are formed in a casing and connected to a downstream side of the variable throttle, and a main valve of the casing. A back pressure chamber formed by an inner wall and a back surface of the main valve; a first flow passage formed inside the main valve, the first flow passage communicating the back pressure chamber with the inflow port via a throttle; A second flow path formed inside and capable of communicating the back pressure chamber with the outflow port, and the maximum load pressure and the discharge connected to either one of the load pressure detection conduit and the discharge pressure detection conduit. A pressure receiving chamber into which either one of the pressures is guided, one end of which is inserted into a through hole formed in the main valve and the other end of which is disposed in the pressure receiving chamber, and which controls the fluid pressure of the back pressure chamber Pyro that operates the main valve Has a preparative member, said pilot member includes a diaphragm portion constituting a valve for communicating or blocking the said back pressure chamber through said second passage and said outlet port,
A first pressure receiving portion which is provided at one end of the pilot member, blocks the inflow port and the second flow path in the through hole, and receives the pressure of the inflow port in the valve opening direction of the throttle portion; A second pressure receiving portion which is provided at the other end of the member and which receives one of the maximum load pressure and the discharge pressure introduced into the pressure receiving chamber in the pressure receiving chamber in a valve closing direction of the throttle portion; A hydraulic valve device is provided in which the 2 pressure receiving portion is in contact with a spring that biases the pilot member in one of a valve closing direction and a valve opening direction of the throttle portion.

Preferably, in the hydraulic valve device, the pressure receiving chamber is connected to the load pressure detecting pipe line to guide the maximum load pressure, and the spring contacting the second pressure receiving portion is the pilot. There is provided a hydraulic valve device characterized in that a member is urged in a valve closing direction of the throttle portion.

Further preferably, in the hydraulic valve device, the pressure receiving chamber is connected to the discharge pressure detecting conduit to guide the discharge pressure, and the spring contacting the second pressure receiving portion is the pilot. There is provided a hydraulic valve device characterized in that a member is urged in a valve opening direction of the throttle portion.

More preferably, in the hydraulic valve device, the directional control valve is provided with the inflow port and the outflow port in communication with a tank port at a neutral position.

[0013]

In the present invention constructed as described above, the load pressure detecting pipe line is connected to the pressure receiving chamber of the pressure compensating portion to guide the maximum load pressure, and the spring which abuts the second pressure receiving portion causes the pilot member to narrow the pilot member. When the first pressure receiving portion of the pilot member in the through hole receives the pressure in the valve opening direction of the throttle portion from the inflow port, the second pressure receiving portion in the pressure receiving chamber receives the pressure. When it is smaller than the sum of the pressure received from the maximum load pressure introduced into the chamber in the valve closing direction of the throttle portion and the spring force that abuts the second pressure receiving portion and urges the throttle portion in the valve closing direction, The pilot member moves in the direction to close the throttle,
The back pressure chamber and the outflow port are shut off. Further, at this time, the pressure oil in the inflow port is guided to the back pressure chamber through the first flow path formed inside the main valve, and the main valve moves due to the fluid pressure in the back pressure chamber to cause inflow. The port is blocked from the outflow port. Further, the pressure of the inflow port rises, and the pressure that the first pressure receiving portion receives in the valve opening direction of the throttle portion is the same as the pressure that the second pressure receiving portion receives in the valve closing direction of the throttle portion and the valve closing direction of the throttle portion. When it becomes larger than the sum of the biasing spring force, the pilot member moves in the direction in which the throttle portion opens, and the back pressure chamber communicates with the outflow port via the second flow path formed inside the main valve. To do.
As a result, the pressure oil guided from the inflow port to the back pressure chamber via the first flow path flows out to the outflow port via the second flow path, but the back pressure is reduced by the throttle provided in the first flow path. Since the pressure in the pressure chamber decreases and the main valve moves toward the back pressure chamber, the inflow port and the outflow port are in direct communication. That is, by the above operation, the pressure in the inflow port connected to the downstream side of the variable throttle is controlled to be higher by the spring force than the maximum load pressure detected by the load pressure detection pipe line, A variable differential pressure type pressure compensator can be realized.

On the other hand, a discharge pressure detection conduit is connected to the pressure receiving chamber of the pressure compensating unit to guide the discharge pressure of the hydraulic pump, and a spring contacting the second pressure receiving unit urges the pilot member in the valve opening direction of the throttle unit. In this case, the first pressure receiving portion of the pilot member in the through hole receives pressure from the inflow port in the valve opening direction of the throttle portion, and the second pressure receiving portion contacts the second pressure receiving portion and urges in the valve opening direction of the throttle portion. When the sum of the spring force of the throttle valve and the second pressure receiving portion in the pressure receiving chamber is smaller than the pressure received by the second pressure receiving portion in the pressure receiving chamber in the valve closing direction of the throttle portion, the throttle valve closes in the valve closing direction. The pilot member moves, and the back pressure chamber and the outflow port are shut off. Further, at this time, the pressure oil in the inflow port is guided to the back pressure chamber through the first flow path formed inside the main valve, and the main valve moves due to the fluid pressure in the back pressure chamber to cause inflow. The port is blocked from the outflow port.

Further, the pressure of the inflow port rises, the pressure at which the first pressure receiving portion of the pilot member in the through hole receives from the inflow port in the valve opening direction of the throttle portion, and the second pressure receiving portion comes into contact with the throttle portion. When the sum of the spring force that biases the valve portion in the valve opening direction becomes larger than the pressure that the second pressure receiving portion in the pressure receiving chamber receives from the discharge pressure guided to the pressure receiving chamber in the valve closing direction of the throttle portion, The pilot member moves in the direction in which the valve opens, and the back pressure chamber communicates with the outflow port via the second flow path formed inside the main valve. As a result, the pressure oil guided from the inflow port to the back pressure chamber via the first flow path flows out to the outflow port via the second flow path, but the back pressure is reduced by the throttle provided in the first flow path. Since the pressure in the pressure chamber decreases and the main valve moves toward the back pressure chamber, the inflow port and the outflow port are in direct communication. That is, by the above operation, the discharge pressure of the hydraulic pump detected by the discharge pressure detection pipeline,
That is, it is possible to realize a constant pressure differential type pressure compensator that controls the pressure on the upstream side of the variable throttle so as to be higher than the pressure on the inflow port connected to the downstream side by the spring force.

In the configuration using the pressure compensator as a variable differential pressure type and the configuration using a constant differential pressure type as described above, a signal for connecting the pressure receiving chamber to the load pressure detecting circuit or the discharge pressure detecting circuit. Most of the structure other than the pipe and the spring in the pressure receiving chamber have the same structure, so that the pressure compensator can be shared. Further, at this time, a through hole which is a signal pipe line acting in the valve opening direction of the throttle part is provided in the pressure compensating part, and a signal pipe line acting in the valve closing direction of the throttle part is selectively connected to the pressure receiving chamber. Since the structure is such that a variable / constant differential pressure type pressure compensation function is selectively obtained by selectively energizing with a spring, it is possible to simplify the control signal pressure line related to the pressure compensation unit. Therefore, the structure of the entire hydraulic valve device can be made common.

Further, the directional control valve allows either the inflow port or the outflow port to communicate with the tank port at the neutral position, so that the pressure compensating unit is not involved in the load sensing control when the operation is in the neutral position and the energy more than necessary is supplied. Loss can be prevented.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. A circuit diagram of a hydraulic circuit provided with the hydraulic valve devices 100 and 200 according to the present embodiment is shown in FIG. The hydraulic valve device 100 is a hydraulic valve device having a variable differential pressure type pressure compensating unit, and the hydraulic valve device 200 is a hydraulic valve device having a constant differential pressure type pressure compensating unit. In the hydraulic valve devices 100 and 200, the same members are designated by the same reference numerals. In FIG. 2, the hydraulic circuit includes a variable displacement hydraulic pump 1, a discharge pipeline 3 connected to the hydraulic pump 1, and a parallel pipeline 5 branched from the discharge pipeline 3 via a branch pipeline 4. 5 and a hydraulic valve device 10 connected to the downstream sides of the parallel pipelines 5, 5, respectively.
0,200 and the hydraulic valve device 1 via the load pipes 6a, 6b
The actuators 7a and 7b, which are driven and controlled to 00 and 200, the detection path 13 for detecting the maximum load pressure of the actuators 7a and 7b, and the pipeline that branches from the detection path 13 and communicates with the tank The throttle 50 and the signal lines 12 and 14 for detecting the discharge pressure of the hydraulic pump 1.
And so-called load sensing control for controlling the discharge capacity of the hydraulic pump 1 so that the discharge pressure of the hydraulic pump 1 connected to the detection path 13 and the signal conduit 12 becomes higher than the maximum load pressure by a predetermined value (described later). The tilt control unit 2 is provided.

The hydraulic valve device 100 has a directional control valve 8 and a pressure compensator 30 which is provided on the downstream side of the directional control valve 8 and controls the differential pressure across the directional control valve 8 to a predetermined value (described later). The detailed structure of the pressure compensator 30 is shown in FIG. 1 and 2, in the casing body 50 of the pressure compensator 30,
An inflow port 10 and an outflow port 11 connected to the downstream side of the directional control valve 8, branch ports 11a and 11b connected to the outflow port 11, and a cylinder chamber 53 into which the main valve 60 is fitted are formed. , The plate 52 and the cover 51 are fixed, and the upper surface of the main valve 60 and the plate 52 are fixed.
A back pressure chamber 54 is formed between and, and a pressure receiving chamber 56 is formed between the plate 52 and the cover 51. Further, in the casing body 50, the actuator 7 described above is provided.
A detection path 13 for detecting the maximum load pressure of the load pressures a and 7b and a signal conduit 14 for detecting the discharge pressure of the hydraulic pump 1 are provided, and the outflow port 11 is a branch port. 11a, the signal conduit 21, the check valve 20, and the signal conduit 22 are connected to the detection conduit 13. The detection path 13 penetrates through the casing 50 and is communicatively connected to the inside of a casing body 50 of another hydraulic valve device 200, which will be described later, and is also connected to the pressure receiving chamber 56 via the signal conduit 32b. The signal line 14 also penetrates through the casing 50 and is communicatively connected within the casing body 50 of another hydraulic valve device 200 described later. In the valve body of the main valve 60,
A first flow path 62 that connects the inflow port 10 and the back pressure chamber 54 to each other through a throttle 63, a through hole 65 that penetrates the main valve 60 in a direction that connects the inflow port 10 and the back pressure chamber 54, A second flow path 64 is formed that allows the pressure chamber 54 and the outflow port 11 to communicate with each other through a part of the through hole 65. The main valve 60 constitutes a pressure compensating valve 31 together with a pilot valve 61 which will be described later, and a seat portion 55 provided at the end portion
The inflow port 10 and the outflow port 11 are communicated / blocked with each other.

The pressure compensator 30 has one end (lower end in the drawing).
Is inserted into the through hole 65 and the other end (upper end in the drawing) is arranged in the pressure receiving chamber 56, and has a pilot valve 61 that controls the pressure in the back pressure chamber 54 to operate the main valve 60. The pilot valve 61 is seatable with the upper end portion of the through hole 65 of the main valve 60, and the back pressure chamber 5 is provided via the second flow path 64.
No. 4 and the outflow port 11 are connected to each other, and the inflow port 10 and the second flow path 64 are cut off in the through hole 65 and the pressure of the inflow port 10 is cut through the signal pipe 32a. And a first pressure receiving portion 61b that receives pressure in the valve opening direction (upward direction in the drawing) of the throttle portion 61a, and the maximum load pressure introduced from the detection path 13 to the pressure receiving chamber 56 via the signal conduit 32b in the pressure receiving chamber 56. The second pressure receiving portion 61c receives pressure in the valve closing direction of the portion 61a (downward in the drawing), and the second pressure receiving portion 61c connects the pilot valve 61 to the closing direction of the throttle portion 61a (downward in the drawing). 32s for biasing to
Is in contact with However, the spring force of the spring 3s is so small that the throttle portion 61a of the pilot valve 61 can be seated on the upper end of the through hole 65 of the main valve 60 when there is no pressure difference between the pressure receiving chamber 56 and the signal conduit 32a. All you need is enough power.

Returning to FIG. 2, the directional control valve 8 has branch ports 11a, 1 connected to the parallel line 5, the tank port 15, the inflow port 10 to the pressure compensation valve 31, and the outflow port 11.
1b and the load pipe 6 connected to the actuator 7a
a, 6b are connected, and the inflow variable throttle unit 80 corresponding to the direction control of the actuator 7a is connected.
a, 80b, direction control units 81a, 81b, and outflow unit 82
a, 82b, a drain conduit 83c for communicating the inflow port 10 of the pressure compensation valve 31 with the tank port 15 in the neutral position, and the outflow port 11 with branch ports 11a, 11b.
Drain line 83 communicating with the tank port 15 via
a and 83b are provided.

On the other hand, the hydraulic valve device 200 includes the directional control valve 8
And a pressure compensator 40 provided on the downstream side thereof to control the differential pressure across the directional control valve 8 to a predetermined value (described later).

The detailed structure of the pressure compensation valve 40 is shown in FIG.
The same members as those of the pressure compensation unit 30 of FIG. 1 are designated by the same reference numerals. 2 and 3, the pressure compensator 40 differs from the pressure compensator 30 described above in that the main difference is that instead of the detection path 13 for detecting the maximum load pressure, the discharge pressure of the hydraulic pump 1 is detected. Is connected to the pressure receiving chamber 56 via the signal pipe 42b, the discharge pressure is guided to the pressure receiving chamber 56, and the second pressure receiving portion 6 disposed in the pressure receiving chamber 56.
1c is in contact with a spring 42s that biases the pilot valve 61 in the valve opening direction (upward direction in the drawing) of the throttle portion 61a, and this spring 42s sets the differential pressure across the direction control valve 8. Therefore, the spring force is relatively small and not minute. The other configuration is almost the same as that of the pressure compensation unit 30.

Further, the directional control valve 8 of the hydraulic valve device 200
Has almost the same structure as the directional control valve 8 of the hydraulic valve device 100, and therefore the description thereof will be omitted.

In the hydraulic circuit configured as described above, for example, when the directional control valve 8 is switched to the right side (to the left side position) in FIG. , The variable throttle portion 80 of the direction control valve 8
a through the inflow port 10, the pressure compensating valve 31, the outflow port 11 and the branch port 11a, the direction control section 81a of the direction control valve 8 and the load pipe 6a, and then the load pipe 6b and the direction control valve. It is returned to the tank via the tank port 15 via the outflow portion 82a of No. 8 of FIG. Further, regarding the hydraulic valve device 200, the variable throttle portion 80 of the directional control valve 8 is provided.
a from the inlet port 10, the pressure compensating valve 41, the outlet port 11 and the branch port 11a, the direction control portion 81a of the direction control valve 8 and the load pipe 6a to flow into the actuator 7b, and then the load pipe 6b and the direction control valve. It is returned to the tank via the tank port 15 via the outflow portion 82a of No. 8 of FIG.

At this time, the hydraulic valve devices 100, 20
0 The differential pressure across the directional control valve 8 is equal to the pressure compensation unit 30.
Alternatively, of the load pressures of the actuators 7a and 7b, which are controlled to a predetermined value by the pressure compensator 40 and are guided via the signal line 21, the check valve 20, and the signal line 22, respectively, the highest load related to the load sensing control. The pressure is guided to the tilt control unit 2 via the detection path 13, and the hydraulic pump 1
The so-called load sensing control is performed in which the discharge capacity of the hydraulic pump 1 is controlled such that the discharge pressure of the hydraulic pump 1 becomes higher than the maximum load pressure by a predetermined value set in advance in the tilt control unit 2.

The pressure compensating operation in the pressure compensating section 30 of the hydraulic valve device 100 at this time will be described in detail below. In the pressure compensating portion 30 shown in FIG. 1, the first pressure receiving portion 61 b of the pilot valve 61 located in the through hole 65 has the inflow port 10
From the maximum load pressure introduced by the second pressure receiving portion 61c in the pressure receiving chamber 56 to the pressure receiving chamber 56 from the maximum load pressure in the valve opening direction of the throttle portion 61a (upward in the drawing). (A downward pressure in the drawing) and a spring force (however, this is minute) of the spring 32s that abuts the second pressure receiving portion 61c and urges the throttle portion 61a in the valve closing direction (downward direction in the drawing). When it is smaller than the sum, the pilot valve 61 is pressed downward in the drawing, whereby the throttle portion 61a of the pilot valve 61 is pressed.
Seats on the upper surface of the main valve 60, and the back pressure chamber 54 and the second flow path 64 are shut off. At this time, the pressure oil in the inflow port 10 is introduced into the back pressure chamber 54 via the first flow passage 62 and the throttle 63 formed inside the main valve 60. The main valve 60 is pressed downward in the drawing by the fluid pressure of (1) to seat at the seat portion 55, and the inflow port 10 and the inflow port 11 are shut off.

The pressure in the inflow port 10 rises, and the pressure received by the first pressure receiving portion 61b of the pilot valve 61 in the valve opening direction (upward direction in the drawing) of the throttle portion 61a is the second pressure receiving portion 6.
When 1c becomes larger than the sum of the pressure received in the valve closing direction of the throttle portion 61a (downward in the drawing) and the spring force of the spring 32s urging in the valve closing direction of the throttle portion 61a (downward in the drawing), the pilot valve 61 Moves upward in the drawing to open the seats of the throttle portion 61a of the pilot valve 61 and the upper surface of the main valve 60,
The second flow path 64 and the back pressure chamber 54 formed inside the main valve 60.
And communicate with each other via the throttle portion 61a. As a result, the pressure oil guided from the inflow port 10 to the back pressure chamber 54 via the first flow path 62 flows out to the outflow port 11 via the second flow path 64. At this time, the pressure oil is provided in the first flow path 62. The pressure in the back pressure chamber 54 decreases due to the pressure drop caused by the throttle 63, and as a result, the main valve 60 is moved upward in the drawing, so that the seat portion 55 of the main valve 60 is also opened and the inflow port 10 and the outflow port 11 are opened. And communicate directly.

That is, when the pressure in the inflow port 10 increases or the maximum load pressure introduced from the detection path 13 decreases, the throttle portion 61a of the pilot valve 61 moves in the valve opening direction (upward direction in the drawing). , The main valve 60 also moves upward so as to follow this, which causes the inflow port 1
It operates to prevent pressure buildup within zero. Further, when the pressure in the inflow port 10 decreases or the maximum load pressure increases, the throttle portion 61a of the pilot valve 61 moves in the valve closing direction (downward in the drawing), and the main valve 60 also follows so as to follow this. It moves downwards and thereby acts to prevent a pressure drop in the inlet port 10. In this manner, the control force in the valve closing direction due to the pressure receiving force of the second pressure receiving portion 61c and the spring force of the spring 32s and the control force in the valve opening direction due to the pressure receiving force of the first pressure receiving portion 61b are balanced. By adjusting the pilot valve 60 and the main valve 60 that follows the pilot valve 60, the pressure in the inflow port 10 connected to the downstream side of the variable throttle portion 80a of the directional control valve 8 is guided to the maximum through the detection path 13. To be higher than the load pressure by the spring force of the spring 32s,
That is, it is possible to realize the pressure compensating unit of the variable differential pressure system, which controls the pressure in the inflow port 10 to be substantially equal to the maximum load pressure.

On the other hand, the pressure compensating operation in the pressure compensating section 40 of the hydraulic valve device 200 at this time will be described in detail below. In the pressure compensator 40 shown in FIG. 3, the pressure received by the first pressure receiver 61b of the pilot valve 61 in the through hole 65 from the inflow port 10 in the valve opening direction of the throttle 61a (upward in the drawing) and the second Abutting against the pressure receiving portion 61c, the throttle portion 61
The sum of the spring force of the spring 42s that urges the valve opening direction a in the valve opening direction (upward direction in the drawing) causes the second pressure receiving portion 61c in the pressure receiving chamber 56 to move from the pump discharge pressure introduced into the pressure receiving chamber 56 to the throttle portion 61a. When the pressure is smaller than the pressure received in the valve closing direction (downward in the drawing), the pilot valve 61 is pressed downward in the drawing, whereby the throttle portion 61a of the pilot valve 61 seats on the upper surface of the main valve 60, and The pressure chamber 54 and the second flow path 64 are shut off. At this time, the pressure oil in the inflow port 10 is the main valve 6
0 is guided into the back pressure chamber 54 via the first flow passage 62 and the throttle 63 formed inside the back pressure chamber 54, and the fluid pressure in the back pressure chamber 54 pushes the main valve 60 downward in the drawing. The seat is formed at the portion 55, and the inflow port 10 and the inflow port 11 are blocked.

Further, the pressure of the inflow port 10 rises, the pressure received by the first pressure receiving portion 61b of the pilot valve 61 in the valve opening direction (upward direction in the drawing) of the throttle portion 61a, and the throttle portion 61a.
When the sum of the spring force of the spring 42s biasing in the valve opening direction (upward in the drawing) of the above is larger than the pressure received by the second pressure receiving portion 61c in the valve closing direction (downward in the drawing) of the throttle portion 61a,
The pilot valve 61 moves upward in the drawing to move the pilot valve 6
The seat between the first throttle portion 61a and the upper surface of the main valve 60 is opened, and the second flow passage 64 formed inside the main valve 60 and the back pressure chamber 54 communicate with each other via the throttle portion 61a. As a result, the pressure oil guided from the inflow port 10 to the back pressure chamber 54 via the first flow path 62 flows out to the outflow port 11 via the second flow path 64. At this time, the pressure oil is provided in the first flow path 62. Aperture 63
The pressure in the back pressure chamber 54 is reduced by the pressure drop due to, and as a result, the main valve 60 is moved upward in the figure, so that the seat portion 55 of the main valve 60 is also opened and the inflow port 10 and the outflow port 1
Direct communication with 1.

That is, when the pressure in the inflow port 10 increases or the discharge pressure introduced from the signal line 14 decreases, the throttle portion 61a of the pilot valve 61 moves in the valve opening direction (upward direction in the drawing). , The main valve 60 also moves upward so as to follow this, whereby the inflow port 10
It works to prevent the rise of pressure inside. Further, when the pressure in the inflow port 10 decreases or the discharge pressure increases,
The throttle portion 61a of the pilot valve 61 moves in the valve closing direction (downward in the drawing), and the main valve 60 also moves downward so as to follow this, thereby preventing the pressure in the inflow port 10 from decreasing. Operate. Thus, the second pressure receiving portion 61c
Control force in the valve closing direction due to the pressure received by the first pressure receiving portion 61b
The pilot valve 61 and the main valve 60 following the pilot valve 61 adjust so that the control force in the valve opening direction caused by the spring force of the spring 42s and the received pressure of the valve 42s are balanced, whereby the variable throttle of the directional control valve 8 is adjusted. The pressure on the upstream side of the portion 80a, that is, the pump discharge pressure is controlled to be higher than the pressure in the inflow port 10 connected to the downstream side of the variable throttle portion 80a by an amount corresponding to the initial biasing force of the spring 42s, in other words. It is possible to realize a pressure compensation unit of a constant pressure difference type, which controls the pressure difference between the pump discharge pressure and the pressure in the inflow port 10 to be maintained at a constant value.

Returning to FIG. 2, on the other hand, the above hydraulic valve device 1
In the hydraulic circuit including 00 and 200, when the directional control valve 8 is switched to the left side (the right side position) in the drawing by the operator, the pressure oil of the hydraulic pump 1 is the variable throttle of the directional control valve 8 similarly to the above. From the portion 80b to the actuator 7a or 7b through the inflow port 10, the pressure compensation valve 31 or 41, the outflow port 11 and the branch port 11b, the direction control unit 81b of the directional control valve 8 and the load pipe line 6b,
It is returned to the tank via the load port 6a and the outflow portion 82b of the direction control valve 8 and the tank port 15. At this time, in the same operation as described above, the differential pressure across the directional control valve 8 is controlled to a predetermined value by the pressure compensating unit 30 or 40, and the maximum load pressure related to the load sensing control is set to the tilt control unit 2. The discharge capacity of the hydraulic pump 1 is subjected to load sensing control.

Further, when the directional control valve 8 is in the neutral position (the position shown in FIG. 2) in which the directional control valve 8 is not operated, the directional control valve 8 is formed with one of the drain conduits 83a, 83b, 83c, so that the outflow port is formed. 11 and the branch ports 11a and 11b are communicated with the tank port 15, so that the signal line 21 of the pressure compensating unit 30 and 40, the outflow port 11, and the withdrawal pressure in the branch ports 11a and 11b can flow through the drain line. Through the tank port 15 to the tank. Therefore, the pressure compensating units 30 and 40 are not involved in the load sensing control, and it is possible to prevent unnecessary energy loss. At this time, the detection path 1
The pressure in 3 is quickly drained to the tank via the throttle 50. As a result, the tilt control unit 2 sets the tilt angle of the hydraulic pump 1 to the minimum tilt angle. Here, for example, when the hydraulic valve devices 100 and 200 of the present embodiment are applied to a hydraulic excavator, the actuator 7a controlled by the variable differential pressure type pressure compensating unit 30 is a swing motor, and the constant differential pressure type pressure compensating unit is used. By using the boom cylinder as the actuator 7b controlled by 40, the boom of the front working unit is raised at the same time as the boom of the front working unit is lifted when loading the dump truck with the soil and sand scooped in the bucket. It is possible to prevent the boom raising speed on the low load side from decreasing even when performing a combined operation of swinging the swing structure.

The hydraulic valve device 1 having the above-mentioned structure and operation
00 and the operation of the hydraulic valve device 200 will be described below. As a comparative example of the present embodiment, a hydraulic valve device 600 having a constant differential pressure type pressure compensating valve in one parallel pipeline, and a hydraulic valve device having a variable differential pressure type pressure compensating valve in the other parallel pipeline. A basic circuit diagram of a hydraulic circuit provided with 500 is shown in FIG. The same members as those of the hydraulic circuit of this embodiment shown in FIG. 2 are designated by the same reference numerals. In addition, in this comparative example, for convenience of description, the hydraulic circuit including the hydraulic valve devices 500 and 600 for controlling the operation of the actuator in only one direction is taken as an example. Valve device 10
A simpler variable throttle 80 is provided to correspond to the directional control valve 8 in the 0, 200, and the load pipes 6a, 6b in the hydraulic valve device 100, 200 are provided.
Is one load pipe 6. In FIG. 4, the hydraulic circuit of this comparative example includes a variable displacement hydraulic pump 1, a discharge pipe line 3 connected to the hydraulic pump 1, and a parallel pipe branched from the discharge pipe line 3 via a branch pipe line 4. Pipe lines 5 and 5 and hydraulic valve devices 5 connected to the downstream sides of the parallel pipe lines 5 and 5, respectively.
00, 600 and the hydraulic valve device 50 via the load pipes 6, 6.
Actuator 7 whose drive is controlled to 0,600 respectively
a, 7b, a detection path 13 for detecting the maximum load pressure of the actuators 7a, 7b, a signal conduit 12 for detecting the discharge pressure of the hydraulic pump 1, and a connection to the detection conduit 13 and the signal conduit 12. The tilting control unit 2 performs so-called load sensing control for controlling the discharge capacity of the hydraulic pump 1 so that the discharge pressure of the hydraulic pump 1 becomes higher than the maximum load pressure by a predetermined value.

The hydraulic valve device 500 has a variable throttle 80 and a pressure compensating valve 31 provided on the downstream side thereof to control the differential pressure across the variable throttle 80 to a predetermined value. In the pressure compensating valve 31, a signal connected to the detection path 13 for detecting the maximum load pressure of the load pressures of the actuators 7a and 7b via the signal conduit 21, the check valve 20, and the signal conduit 22. The maximum load pressure is introduced in the valve closing direction of the pressure compensating valve 31 via the conduit 32b, so that the control force in the valve closing direction is applied together with the spring 32s, while the variable throttle 80 is connected to the inflow port 10 on the downstream side. The pressure on the downstream side of the variable throttle 80 is guided in the valve opening direction of the pressure compensating valve 31 via the signal line 32a and imparts a control force in this direction. As a result, the pressure compensating valve 31 makes the pressure in the inflow port 10 connected to the downstream side of the variable throttle 80 higher than the maximum load pressure introduced from the detection path 13 by the spring force of the spring 32s. That is, it is possible to perform pressure compensation by a variable differential pressure system, which is controlled so as to be approximately equal to the maximum load pressure.

On the other hand, the hydraulic valve device 600 includes a variable throttle 80.
And a pressure compensating valve 41 provided on the upstream side thereof to control the differential pressure across the variable throttle 80 to a predetermined value. In the pressure compensating valve 41, the upstream pressure of the variable throttle 80 is guided in the valve closing direction of the pressure compensating valve 41 via the signal conduit 42b connected to the conduit 9 on the upstream side of the variable throttle 80. Direction control force is applied, the load pressure of the actuator 7b, that is, the downstream pressure of the variable throttle portion 80 is opened by the pressure compensating valve 41 via the signal conduit 42a connected to the inflow port 10 on the downstream side of the variable throttle 80. By being guided in the direction,
A control force in the valve opening direction is applied together with the spring 42s.
As a result, the pressure compensating valve 41 controls the pressure of the pipe line 9 connected to the upstream side of the variable throttle 80 so as to be higher than the load pressure of the actuator 7b by the spring force of the spring 42s. It enables system pressure compensation.

The hydraulic circuit according to the present comparative example has the above-described structure. When it is applied to a hydraulic excavator, for example, the actuator 7a controlled by the variable differential pressure type pressure compensating valve 31 is swung like the present embodiment. Actuator 7b that is a motor and is controlled by a constant pressure difference type pressure compensation valve 41
By using the boom cylinder as a boom cylinder, for example, when carrying out the work of loading earth and sand scooped into a bucket into a dump truck, the boom of the front working unit is raised and at the same time the upper swing body equipped with this front working unit is swung. Even when the operation is performed, it is possible to prevent the boom raising speed on the low load side from decreasing.

However, the constant pressure differential type pressure compensation valve 3
The 1 and variable differential pressure type pressure compensating valves 41 are independent valves having completely different structures, and no consideration is given to the common use of these valves, and it is difficult to make them common. Also, the pressure compensation valve 41
Are arranged on the upstream side of the variable throttle 80, whereas the pressure compensating valve 31 is arranged on the downstream side of the variable throttle 80. Therefore, the structure of the entire hydraulic valve device 600, 500 including them is made common. However, the control signal pressure line related to the pressure compensating valve becomes complicated. These make it difficult to reduce the size and manufacturing cost of the hydraulic valve device.

On the other hand, the hydraulic valve device 200 of this embodiment
The variable differential pressure type pressure compensating valve 30 provided in the above and the constant differential pressure type pressure compensating valve 40 provided in the hydraulic valve device 100 of the present embodiment are apparent from a comparison between FIG. 1 and FIG. In addition, since most of the structure is the same except for the signal conduits 32b and 42b connecting the pressure receiving chamber 56 and the detection path 13 or the signal conduit 14 and the springs 32s and 42s in the pressure receiving chamber 56, the pressure compensator 30 , 40 can be shared. Further, at this time, the signal conduit 42a acting in the valve opening direction of the throttle portion 61a is provided in the pressure compensating parts 30, 40, and the signal conduits 32b, 42b are selectively connected to the pressure receiving chamber 56 so that the spring 32s, Since the pressure compensation function of the variable / constant differential pressure type is selectively obtained by selectively energizing at 42 s, the control signal pressure lines related to the pressure compensating units 30 and 40 can be simplified. Further, in either the case of the variable differential pressure type or the constant differential pressure type, the pressure compensating units 30 and 40 are arranged on the downstream side of the variable throttle unit 80 of the directional control valve 8, and the hydraulic valve devices 100 and 200 as a whole. The structure can be shared. Therefore, these can reduce the size of the hydraulic valve device and reduce the manufacturing cost.

In the above embodiment, the hydraulic circuit provided with two hydraulic valve devices, one hydraulic valve device 100 and one hydraulic valve device 200, has been described as an example, but the present invention is not limited to this. The above hydraulic valve device may be provided. That is, while extending the branch pipeline 4 to provide the parallel pipeline 5, the detection pipeline 13 and the signal pipeline 14 are extended and connected to the parallel pipeline 5, the detection pipeline 13, and the signal pipeline 14,
Further, the hydraulic valve device 100 or 200 may be provided, and in this case, the same effect is obtained.

[0042]

According to the present invention, the pressure receiving chamber is connected to the load pressure detection circuit or the discharge pressure detection circuit in the configuration using the pressure compensating unit as the variable differential pressure type and the configuration using the constant pressure differential type. Most of the components except the signal conduits that have the same structure have the same structure, so that the pressure compensator can be shared. Further, at this time, the control signal pressure line related to the pressure compensator can be simplified. Therefore, the structure of the entire hydraulic valve device can be made common. By these,
The hydraulic valve device can be downsized and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a detailed structure of a variable differential pressure type pressure compensator included in a hydraulic valve device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of a hydraulic circuit provided with a hydraulic valve device.

FIG. 3 is a cross-sectional view showing a detailed structure of a constant pressure difference type pressure compensator included in a hydraulic valve device according to an embodiment of the present invention.

FIG. 4 is a circuit diagram of a hydraulic circuit provided with a hydraulic valve device according to a comparative example of an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hydraulic pump 2 Tilt control part (pump control means) 7a Actuator 7b Actuator 8 Directional control valve 10 Inflow port 11 Outflow port 12 Signal line (discharge pressure detection line) 13 Detection line (load pressure detection line) 14 Signal Pipe line (discharge pressure detection pipe line) 15 Tank port 21 Signal pipe line 22 Signal pipe line 30 Pressure compensating part 31 Pressure compensating valve 32a Signal pipe line 32b Signal pipe line 32s Spring 40 Pressure compensating part 41 Pressure compensating valve 42a Signal pipe line 42b Signal pipe 42s Spring 50 Casing body 54 Back pressure chamber 56 Pressure receiving chamber 60 Main valve 61 Pilot valve (pilot member) 61a Throttling portion 61b First pressure receiving portion 61c Second pressure receiving portion 62 First flow passage 63 Throttling 64 Second flow Line 65 Through-hole 80a Variable throttle part 80b Variable throttle part 83a Drain pipe line 83b Drain pipe line 83c Drain pipe 100 Hydraulic valve device 200 Hydraulic valve device

Claims (4)

[Claims] 1. A variable displacement hydraulic pump, a load pressure detection conduit for detecting the maximum load pressure of a plurality of actuators driven by the pressure oil of the hydraulic pump, and a discharge pressure detection for detecting the discharge pressure of the hydraulic pump. A pump control means connected to the pipeline, the load pressure detection pipeline, and the discharge pressure detection pipeline to control the discharge capacity of the hydraulic pump so that the discharge pressure becomes higher than the maximum load pressure by a predetermined value. A plurality of hydraulic circuits are provided, each of which has a directional control valve having a variable throttle and a pressure compensator for controlling the differential pressure across the variable throttle to a predetermined value. In the hydraulic valve device for controlling the drive of one actuator, the pressure compensating portion is configured to connect and disconnect an inflow port and an outflow port, which are formed in a casing and connected to a downstream side of the variable throttle, from each other. And a back pressure chamber formed by the inner wall of the casing and the back surface of the main valve, and a first flow path formed inside the main valve and communicating the back pressure chamber with the inflow port via a throttle. A second flow path formed inside the main valve and capable of communicating the back pressure chamber with the outflow port; and the second flow path connected to one of the load pressure detection conduit and the discharge pressure detection conduit A pressure receiving chamber into which either one of the load pressure and the discharge pressure is guided, one end of which is inserted into a through hole formed in the main valve and the other end of which is arranged in the pressure receiving chamber, and the fluid pressure of the back pressure chamber. And a pilot member that operates the main valve by operating the pilot valve, and the pilot member constitutes a valve that connects and disconnects the back pressure chamber and the outflow port via the second flow path. The throttle portion and the penetrating portion provided at one end of the pilot member. A first pressure receiving portion for blocking the inflow port and the second flow path in the hole and receiving the pressure of the inflow port in the valve opening direction of the throttle portion; and the pressure receiving chamber provided at the other end of the pilot member. In the pressure receiving chamber, a second pressure receiving portion for receiving one of the maximum load pressure and the discharge pressure in the valve closing direction of the throttle portion, the second pressure receiving portion including the pilot member A hydraulic valve device, wherein the hydraulic valve device is in contact with a spring that urges the throttle portion in one of a valve closing direction and a valve opening direction. 2. The hydraulic valve device according to claim 1, wherein the pressure receiving chamber is connected to the load pressure detecting conduit to guide the maximum load pressure, and the spring abutting the second pressure receiving portion is A hydraulic valve device, wherein the pilot member is urged in a valve closing direction of the throttle portion. 3. The hydraulic valve device according to claim 1, wherein the pressure receiving chamber is connected to the discharge pressure detecting conduit to guide the discharge pressure, and the spring abutting on the second pressure receiving portion comprises:
A hydraulic valve device, wherein the pilot member is biased in a valve opening direction of the throttle portion. 4. The hydraulic valve device according to claim 1, wherein the directional control valve communicates either the inflow port or the outflow port with a tank port at a neutral position.