JP2000018205A - Directional switching valve device with pressure compensation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a before-orifice type valve with pressure compensation small-sized and capable of serving as a high leakage preventing function by using a poppet valve constituting this valve with pressure compensation and providing a function as a load check valve therefor. SOLUTION: This control valve device with pressure compensation is provided with a main valve 20 consisting of a poppet valve body for communicating and cutting off communication with inflow and outflow ports 201, 202 of the valve with pressure compensation 7, a back pressure chamber 70, and first and second pilot valves 30, 40 for operating the main valve 20 by controlling pressure oil flowing from the inflow port 201, the back pressure chamber 70 to the outflow port 202 so as to change fluid pressure in the back pressure chamber 70. Upstream and downstream pressures of a meter-in variable restriction 63a are allowed to work on the pressure receiving parts 46, 48 of the second pilot valve 40. The main valve 20 is retained at a cut-off position by leading load pressure to the back pressure chamber 70 when discharge pressure of a pump is lower than load pressure of the actuator 6, and the pressure of the back pressure chamber 70 is decreased so as to open the main valve 20 when the discharge pressure of the pump is higher than the load pressure. Accordingly, differential pressure before/after the meter-in variable restriction 63a is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a directional control valve device provided in a hydraulic machine such as a hydraulic shovel or a hydraulic crane, and more particularly to a discharge of a hydraulic pump by detecting a maximum load pressure among load pressures of a plurality of actuators. A meter-in variable throttle and a pressure compensation valve located upstream of the variable throttle are provided in a hydraulic system that performs load sensing control that controls the displacement of the hydraulic pump so that the pressure becomes higher than the maximum load pressure by a predetermined value. The present invention relates to a direction switching valve device with pressure compensation for controlling the flow rate of pressure oil supplied from a hydraulic pump to an actuator.

[0002]

2. Description of the Related Art In order to supply hydraulic pressure discharged from a hydraulic pump to a hydraulic actuator, a plurality of directional control valves are connected in parallel to the discharge path of the hydraulic pump, and the directional control valves are connected to the hydraulic oil from the actuator. May be connected to the tank so as to be able to be discharged, and the plurality of direction switching valves may be switched. However, when a plurality of directional control valves are connected in parallel as described above, when a plurality of actuators are driven at the same time, the pump discharge flow rate is supplied to the low-load side actuator to the priority hydraulic pressure, and the high-load side actuator is Driving is no longer compensated.

To solve this problem, for example, a directional switching valve device using a poppet valve-type pressure compensating valve of a meter-in throttle downstream arrangement (after orifice type) as disclosed in Japanese Patent Application Laid-Open No. 8-135604 has been proposed. ,
With this pressure compensating valve, combined driving can be achieved. Further, in this known example, the pressure compensation valve of the poppet valve type is of a constant differential pressure type (a method of keeping the differential pressure across the meter-in throttle constant) and a variable differential pressure type (load sensing the differential pressure across the meter-in throttle). The parts are shared between the case where the pressure is changed in conjunction with the differential pressure (shunting function type) and the manufacturing cost is reduced.

Japanese Patent Application Laid-Open No. 4-244605 discloses that a load check valve is used also as a variable differential pressure type pressure compensating valve arranged upstream of a meter-in throttle (before orifice type), and a signal receiving pressure of the pressure compensating valve is received. There is disclosed an apparatus in which a pilot valve of a portion is brought into contact with a valve body of a pressure compensating valve, and the pilot valve has a function of reducing a discharge pressure of a hydraulic pump to generate a control pressure equivalent to a maximum load pressure.

[0005]

During operation of the directional control valve device, immediately after the opening of the meter-in throttle, the discharge pressure of the hydraulic pump is transiently lower than the load pressure. A load check valve is generally provided to prevent pressure oil from flowing back to the pump side. In a direction switching valve device provided with a pressure compensating valve, a load check valve is usually provided separately from the pressure compensating valve. The valve element of the load check valve is constituted by a poppet valve (seat valve) that sits on a seat portion of the casing body when the valve is closed to minimize leakage of pressure oil.

The same applies to the after-orifice type pressure compensating valve described in JP-A-8-135604, and a load check valve is provided separately from the pressure compensating valve.
In addition, since the pressure compensating valve is an after-orifice type, if the main spool of the direction switching valve is structured such that the meter-in throttle portion also functions as the direction switching portion, the pressure compensating valve and the load check valve are switched for each switching direction. If the main spool of the directional control valve has a structure in which the meter-in restrictor does not double as the direction switcher, the meter-in restrictor must be disposed on the main spool. It is necessary to separately provide a land for the direction switching section and a land for the direction switching section. Correspondingly, it is necessary to provide a meter-in throttle section and a port for the direction switching section in the casing body. For this reason, the structure of the directional switching valve device itself becomes large, and the production of a plurality of valve bodies causes a disadvantage that new production and production costs are increased.

The pressure compensating valve described in JP-A-4-244605 is of a before-orifice type, so that the spool structure of the directional control valve can be simplified. Further, since the load check valve is also used as the pressure compensating valve, it is not necessary to separately provide a load check valve. However, this prior art pressure compensating valve is a spool type in which the valve body slides in a hole provided in the valve body (casing body) to open and close the opening. A considerable amount of pressure oil leaks from the sliding gap between the outer peripheral surface of the valve body and the inner peripheral surface of the valve body hole, and the function as a load check valve is incomplete compared to a load check valve consisting of a normal poppet valve. It is.

An object of the present invention is to provide a valve element of a before orifice type pressure compensating valve by a poppet valve and to provide the pressure compensating valve with a load check valve function.
An object of the present invention is to provide a pressure-compensated directional control valve device which is small and can perform an excellent leak prevention function.

[0009]

(1) In order to achieve the above object, the present invention comprises a variable displacement hydraulic pump and a plurality of actuators driven by hydraulic oil of the hydraulic pump. A hydraulic system for performing load sensing control for detecting a maximum load pressure among load pressures of a plurality of actuators and controlling a discharge capacity of the hydraulic pump so that a discharge pressure of the hydraulic pump is higher than the maximum load pressure by a predetermined value. A directional control valve provided with a variable throttle of meter-in and a pressure compensating valve located upstream of the variable throttle to control a flow rate of pressure oil supplied from the hydraulic pump to a corresponding actuator. In the device, the pressure compensating valve has an inflow port connected to a discharge path of the hydraulic pump and an outflow port connected to the variable throttle. A casing main body, a main valve disposed in the casing main body, the main valve including a poppet valve body communicating with and shutting off the inflow port and the outflow port; and a back pressure chamber formed in the casing main body at a back of the main valve. And pilot valve means for controlling the flow of pressurized oil to the inflow port, the back pressure chamber, and the outflow port to change the fluid pressure in the back pressure chamber to operate the main valve. Directly or indirectly act on at least the upstream pressure and the downstream pressure of the variable throttle of the meter-in, and when the discharge pressure of the hydraulic pump is lower than the load pressure of the actuator, guide the load pressure to the pressure chamber to guide the main valve. When the discharge pressure of the hydraulic pump becomes higher than the load pressure of the actuator, the pressure of the back pressure chamber is reduced to open the main valve, and the meter-in And controls the differential pressure across the variable throttle.

As described above, the inflow port of the pressure compensating valve is connected to the discharge path of the hydraulic pump, and the outflow port is connected to the meter-in variable throttle to form a before-orifice-type pressure compensating valve. When the discharge pressure of the hydraulic pump becomes higher than the load pressure of the actuator, the pressure in the back pressure chamber is reduced to open the main valve, and the difference between the front and rear of the meter-in variable throttle is provided. By controlling the pressure, it is possible to function as a before-orifice-type pressure compensating valve. Further, the main valve of the pressure compensating valve is constituted by a poppet valve body, and when the discharge pressure of the hydraulic pump is lower than the load pressure of the actuator, the load pressure is guided to the back pressure chamber to hold the main valve in the shut-off position, A load check function with little leakage similar to a load check valve composed of a normal poppet valve element can be performed. As a result, the spool of the directional control valve can have a simple configuration in which the meter-in throttle portion also serves as the directional switch portion, and can perform a load check function with high sealability, and the directional valve device can perform a small and excellent leak prevention function. Can be.

(2) In the above (1), preferably,
The main valve is formed inside the main valve, a first flow path communicating the back pressure chamber and the inflow port through a throttle, and a first flow path formed inside the main valve, the back pressure chamber and the outflow port. A second flow path to be communicated with, and a valve hole formed inside the main valve and having both ends opened at the inflow port and the back pressure chamber; and the pilot valve means is provided in the valve hole of the main valve. A first pilot valve formed of a poppet valve body to be disposed, and a second pilot valve configured separately from the first pilot valve and disposed on the back pressure chamber side, wherein the first pilot valve includes: A first position in which the pressure of the inflow port and the pressure of the outflow port via the second flow path are opposed to each other in the axial direction to cut off the inflow port and the first flow path; Between a second position in contact with the valve and communicating the inflow port with the first flow path; The second pilot valve is configured to closely slide within the valve hole, and the second pilot valve restricts a flow path between the valve hole and an opening of the valve hole on the back pressure chamber side, and from the back pressure chamber to the second flow path. A throttle section for controlling the flow of pressure oil, a first and a second pressure receiving section for receiving pressure in a direction to open a flow path of the throttle section, and the throttle section opposing the first and second pressure receiving sections. And third and fourth pressure receiving portions that act to receive pressure in a direction that restricts the flow path of
The pressure of the outflow port via the second flow path is guided to the first pressure receiving portion, the downstream pressure of the meter-in variable throttle is guided to the second pressure receiving portion, and the maximum load pressure equivalent to the third pressure receiving portion is guided to the third pressure receiving portion. One of a pressure and a discharge pressure of the hydraulic pump is led, and an upstream pressure of the meter-in variable throttle is led to the fourth pressure receiving portion.

Accordingly, when the discharge pressure of the hydraulic pump has not reached the pressure at which the actuator can be driven, the load pressure of the actuator is led to the outflow port as the upstream pressure of the meter-in variable throttle, and this load pressure is applied to the first pilot valve. And the second pilot valve are separated from each other, and the first pilot valve composed of a poppet valve body is seated on the seat portion, and shuts off the first flow path in the main valve and the inflow port. For this reason, the pressure in the back pressure chamber also becomes the load pressure of the actuator, and the main valve is kept at the shut-off position, so that it can function as a load check valve.

When the discharge pressure of the hydraulic pump reaches a pressure sufficient for driving the actuator, the first pilot valve separates from the seat portion to communicate the inflow port with the first flow path, and to release the first pilot valve. Abuts on the second pilot valve and moves integrally, thereby giving a control force in the direction of opening the flow path of the throttle portion of the second pilot valve. Also, at this time, the first flow path and its restriction from the inflow port,
Pilot flow is generated through the back pressure chamber and the throttle section to the outlet port via the second flow path, and the pressure in the back pressure chamber is reduced by the pressure drop due to the throttle in the first flow path. The valve opens to communicate with the outflow port. When the main valve opens in this manner, the flow path of the throttle section of the second pilot valve is throttled, and the pressure of the back pressure chamber is controlled to be higher than the pressure of the second flow path (pressure of the outflow port). However, at this time, if the gap of the flow path of the throttle section becomes too small, the main valve is pushed back in the valve closing direction by the pressure of the back pressure chamber, so that the main valve is finally controlled to be balanced with a small gap with respect to the throttle section. Is done.

At this time, the downstream pressure of the meter-in variable throttle is guided to the second pressure receiving portion of the second pilot valve, and the upstream pressure of the meter-in variable throttle is guided to the fourth pressure receiving portion. Since the pressure of the inflow port (discharge pressure of the hydraulic pump) acts indirectly via the first pilot valve on the first pressure receiving portion of the second pilot valve that operates integrally with the valve, the third pressure receiving portion When a pressure equivalent to the maximum load pressure is introduced to the second pilot valve, the second pilot valve and the first pilot valve abutting on the second pilot valve are determined by the magnitude relationship between the differential pressure across the meter-in variable throttle, the discharge pressure of the hydraulic pump and the differential pressure between the maximum load pressure. The pilot valve moves, and the main valve moves following the action of the throttle section. Therefore, the upstream pressure of the meter-in variable throttle changes, and the differential pressure before and after the meter-in variable throttle is controlled to be equal to the differential pressure between the discharge pressure of the hydraulic pump and the maximum load pressure. That is, the pressure compensating valve functions as a variable differential pressure type pressure compensating valve, and performs a branch control function.

Further, when the discharge pressure of the hydraulic pump is led to the third pressure receiving portion, the control force of the third pressure receiving portion and the control force of the first pressure receiving portion on which the discharge pressure of the hydraulic pump acts indirectly. Since the compensating differential pressure setting spring is provided separately, the second pilot valve and the first pilot valve in contact with the second pilot valve move according to the magnitude relationship between the differential pressure across the meter-in variable throttle and the force of the spring. Then, the main valve also moves following the action of the above-described throttle portion. This movement of the main valve changes the upstream pressure of the meter-in variable throttle, and controls the differential pressure across the meter-in variable throttle to be equal to the set value of the spring. That is, the pressure compensating valve functions as a constant differential pressure type pressure compensating valve, and the pressure compensating function is performed.

(3) In the above (2), preferably, the second pilot valve is formed in the second pilot valve as an upstream pressure of a meter-in variable throttle guided to the fourth pressure receiving portion. The pressure in the back pressure chamber is led through an internal passage.

(4) In the above (2), the second pilot valve is provided with an internal passage formed in the second pilot valve as the upstream pressure of the meter-in variable throttle guided to the fourth pressure receiving portion and the second pilot valve. The pressure at the outlet port may be led through two flow paths.

(5) In the above (2), the second pilot valve is provided as a pressure upstream of a meter-in variable throttle guided to the fourth pressure receiving portion via a flow passage formed in the casing body. The pressure on the inlet side of the variable throttle may be derived.

(6) Further, in the above (2), preferably, the main valve and the first and second pilot valves are coaxially arranged.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

First, a first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a diagram showing a configuration of a directional control valve device with pressure compensation according to a first embodiment of the present invention, together with a hydraulic circuit.

In FIG. 1, reference numeral 250 denotes the entire directional switching valve device with pressure compensation according to the present embodiment. The directional switching valve device 250 is constituted as a multiple valve composed of a plurality of unit valves. Are indicated at 251.
Hereinafter, the unit valve 251 will be appropriately referred to as a direction switching valve device, and description thereof will be made.

The direction switching valve device 251 has a pressure compensating valve 7 and a direction switching valve 8 having meter-in throttles 63a and 63b, which are variable throttles. The parallel oil passage 4 from the discharge passage 3 of the hydraulic pump 1 is The directional control valve 8 is provided downstream of the outlet port 202 of the pressure compensating valve 7 and connected to the inflow port 201 of the pressure compensating valve 7. , The hydraulic cylinder 6). Further, the discharge path 3 of the hydraulic pump 1 is connected to a plurality of similar directional switching valve devices (not shown), and is similarly connected in parallel to a plurality of actuators.

The direction switching valve 8 is a signal path 8 connected to the downstream side of the meter-in throttles 63a and 63b during the switching operation.
a, 8b, and a signal path 8c connected to the tank 5 when the operation is neutral. When the directional control valve 8 is switched, the meter-in throttles 63a, 63b are switched by the signal path 8a or 8b.
The pressure on the downstream side (load pressure of the actuator 6) is guided to the signal path 12a as a signal pressure, and when the operation of the directional control valve 8 is neutral, the tank pressure is guided to the signal path 12a by the signal path 8c. The signal path 12a is connected to the shuttle valve 11 together with the signal path 12b on the left-hand side of the direction switching valve device side related to another actuator, and its output path 12c is further connected to the lower right-hand side direction related to another actuator in the figure. The highest load pressure detection path is formed by connecting the signal paths 12a and 12ba to the shuttle valve 11 for all the directional control valve apparatuses as described above, and the maximum load pressure detection path is formed. The output path 12c is the detection path 1
3 and the maximum load pressure is detected in the detection path 13.

The maximum load pressure detected by the detection path 13 is guided to the tilt control unit 2 of the hydraulic pump 1, and the tilt control unit 2
Controlling the discharge capacity of the hydraulic pump 1 so that the discharge pressure of the hydraulic pump 1 becomes constant pressure higher than the maximum load pressure.
Generally, variable capacity control called load sensing control is performed.

Reference numeral 200 denotes a casing body of the directional control valve device 251. The casing body 200 has the above-mentioned inflow port 201 and outflow port 202, a flow path 205 connecting these two ports, and a cylinder opening to the outflow port 202. A main valve 20 formed of a poppet valve body of the pressure compensating valve 7 is inserted into the cylinder chamber 200b, and a seat portion 25 at an end of the main valve 20 is provided on the outflow port 202 side of the flow path 205. The inflow port 201 and the outflow port 202 are shut off or communicate with each other by sitting on and separating from the opening.

An annular plate 51 and a tubular plug 52 are also fixed to the casing body 200, and a back pressure chamber 70 is formed between the back of the main valve 20 of the cylinder chamber 200b and the plate 51. In the back pressure chamber 70, a weak spring 50s for holding the main valve 20 at the illustrated shut-off position when the operation of the directional control valve 8 is neutral is arranged.

In the valve body of the main valve 20 of the pressure compensating valve 7, a first flow path 22 for communicating the inflow port 201 with the back pressure chamber 70 through the throttle 23, and the inflow port 201 and the back pressure chamber 70.
And the second flow path 24 that connects the back pressure chamber 70 and the outflow port 202 through the opening of the valve hole 21 on the back pressure chamber 70 side. ing.

Further, the first pilot valve 3 is used as pilot valve means for controlling the opening and closing of the back pressure chamber 70 and the second flow path 24 to change the fluid pressure in the back pressure chamber 70 and to operate the main valve 20.
0 and a second pilot valve 40 are provided.

The first pilot valve 30 is provided in the valve hole 1 of the main valve 20.
A plug 3 having a poppet valve body to be inserted into the inside 2, and having a seat portion 34 capable of seating the end 31 of the first pilot valve 30 in an opening on the inflow port 201 side in the valve hole 21.
3, the portion between the inflow port 201 and the first flow path 22 in the valve hole 21 is divided into a first pressure receiving chamber 71 and a second pressure receiving chamber 72. The first pilot valve 30 cuts off the first flow path 22 and the second flow path 24 in the valve hole 21 and forms a third pressure receiving chamber 73 in an opening portion of the second flow path 24 in the valve hole 21. are doing.

Here, the first pilot valve 30 is connected to the pressure of the inflow port 201 led to the first pressure receiving chamber 71 and the outlet port 20 led to the third pressure receiving chamber 73 via the second flow path 24.
The two pressures oppose each other in the axial direction, and slide in close contact in the valve hole 21 between the shut-off position and the open position depending on the magnitude of the two pressures.
That is, when the pressure at the inflow port 201 is smaller than the pressure at the outflow port 202, the first pilot valve 30
4 (blocking position), blocks the flow of fluid from the first flow path 22 to the inflow port 201, and separates from the seat portion 34 when the pressure of the inflow port 201 becomes greater than the pressure of the outflow port 202 (open position). ), The inflow port 201 and the first flow path 22 are communicated. In the latter open position, the other end 32 of the first pilot valve 30 is connected to the second pilot valve 4.
The first pilot valve 30 and the second pilot valve 40 operate integrally by applying a control force in the valve opening direction to the second pilot valve 40 by contacting one end of the first pilot valve 0.

The second pilot valve 40 has a plate 5 so that one end thereof is located on the back pressure chamber 70 side of the main valve 20.
1 and a plug 52, and a tapered throttle portion 42 and a stem portion 43 at the tip thereof are provided at one end portion located on the back pressure chamber 70 side, and the throttle portion 42 is a valve hole of the main valve 20. 2
The flow path between the back pressure chamber 70 and the second flow path 24 is controlled by restricting the flow path between the back pressure chamber 70 and the seat 26 formed in the opening on the back pressure chamber 70 side, and the stem section 43 Is inserted into the valve hole 21 so that the tip thereof faces the third pressure receiving chamber 73, and the pressure is applied to the tip of the stem portion 43 in the direction of opening the flow path of the throttle portion 42 (the valve opening direction of the main valve 20). 1 pressure receiving part 45
Is provided.

Further, the plug 5 in the casing body 200
Signal ports 203 and 204 are formed around 2, a signal path 12 a is connected to the signal port 203, and a detection path 13 is connected to the signal port 204.

A piston portion 44 is formed in a portion of the second pilot valve 40 which is inserted into the plug 52, and the fourth pressure receiving chamber 74 and the fifth pressure receiving portion 74 are formed by the piston portion 44 and the plug 52.
A fourth pressure receiving chamber 74 is formed with the plug 52.
Communicates with the signal port 203 through the hole 54, and acts on the annular end surface of the piston portion 44 in the fourth pressure receiving chamber 74 to open the flow path of the throttle portion 42 (the direction in which the main valve 20 opens). The second pressure receiving portion 46 is provided, and the fifth pressure receiving chamber 75 communicates with the signal port 204 through the hole 55 of the plug 52,
A throttle portion 42 is formed on the annular end surface of the piston portion 44 in the pressure receiving chamber 75.
A third pressure receiving portion 47 is provided which receives a pressure in a direction (a valve closing direction of the main valve 20) that restricts the flow path.

The open end of the plug 52 on the side opposite to the back pressure chamber 70 is closed by the plug 53, and the second
Piston shaft portion 44 of pilot valve 40 on the side opposite to back pressure chamber 70
A sixth pressure receiving chamber 76 is formed between a and the plug 53,
The sixth pressure receiving chamber 76 communicates with the back pressure chamber 70 via an oil hole 41 formed in the second pilot valve 40, and the end of the piston shaft portion 44 a of the second pilot valve 40 in the sixth pressure receiving chamber 76. The portion is provided with a fourth pressure receiving portion 48 that receives a pressure in a direction that restricts the flow path of the throttle portion 42 (the valve closing direction of the main valve 20). Further, the second pilot valve 40 is provided in the sixth pressure receiving chamber 76.
A weak spring 50p for holding the position is provided for urging the valve in the direction of opening the flow path of the throttle section 42 (the valve opening direction of the main valve 20).

As described above, the second pilot valve 40 is provided with the urging force in the direction of opening the flow path of the throttle portion 42 by the spring 50p and the throttle portion 4 by the first pressure receiving portion 45 and the second pressure receiving portion 46.
The control force in the direction of opening the second flow path and the control force of the third pressure receiving section 47 and the fourth pressure receiving section 48 in the direction of restricting the flow path of the throttle section 42 are opposed to each other. . Here, as shown in parentheses, the second pilot valve 40
Moves in a direction to open the flow path of the throttle section 42, the main valve 20
Operates in the valve opening direction, and the second pilot valve 40
When the main valve 20 moves in the direction to restrict the second flow path, the main valve 20 operates in the valve closing direction (described later).

The operation of the directional control valve device 251 including the pressure compensating valve 7 of the present embodiment configured as described above will be described.

When all of the plurality of directional control valves including the directional control valve 8 are in operation neutral, the signal path 12a and the detection path 13
Is the pressure of the tank 5, and the hydraulic pump 1 is unloaded by an unload valve (not shown).

At this time, the discharge pressure of the hydraulic pump 1 (hereinafter referred to as the pump pressure) is guided to the inflow port 201 and the first pressure receiving chamber 71, opening the first pilot valve 30 and causing the second pressure receiving chamber 7 to open.
2. The pump pressure is guided to the back pressure chamber 70 via the first flow path 22. Further, the pump pressure is also guided to the sixth pressure receiving chamber via the oil hole 41 in the second pilot valve 40. Therefore, the first
The pilot valve 30 is in an equilibrium state in which the pump pressure is received, and the control pressure in the opening direction of the first pressure receiving portion 45 of the second pilot valve 40 and the fourth pressure receiving portion 4 of the second pilot valve 40.
Each of the control pressures in the limiting direction 8 is a pump pressure. on the other hand,
The second pressure receiving portion 46 and the third pressure receiving portion 4 of the second pilot valve 40
The control pressure of 7 is the tank pressure. Therefore, the second pilot valve 40 is fully opened in the drawing in which the throttle portion 42 is separated from the seat portion 26 of the main valve 20 by the very small initial biasing force of the spring 50, and the main valve 20 is in the inflow port 201 and the outflow port 202. The pump pressure acts on both the pressure receiving surface of each of the above and the pressure receiving surface in the back pressure chamber 70, and the inflow port 201 and the outflow port 201 are caused by the very small initial biasing force of the spring 50 s inserted into the back pressure chamber 70. The state shown in FIG.

In this state, the inflow port 201 and the outflow port 202 are connected to each other by the pilot passage from the first flow path 22 to the second flow path 24 through the back pressure chamber 70, which is a problem. Not be. However, if it is necessary to shut off the pilot flow path even when the operation is in the middle of operation, a weak spring may be provided for the first pilot valve 30 to initially bias it in the valve closing direction.

When the directional control valve 8 is switched to connect the meter-in throttle 63a to the outflow port 202, the load pressure of the actuator 6 is changed to the signal path 1 via the signal path 8a.
2a, and the load pressure is further guided to the signal port 203 and the shuttle valve 11. Further, the load pressure guided to the shuttle valve 11 is detected as the maximum load pressure in the detection path 13, and the maximum load pressure is guided to the signal port 204, and also to the tilt control unit 2 of the hydraulic pump 1, and Sensing control is performed.

Therefore, at this time, the first pilot valve 3
At 0, the pump pressure, which is the pressure of the inflow port 201, and the upstream pressure of the meter-in throttle 63a, which is the pressure of the outflow port 202, are receiving pressure, and among the pressure receiving portions of the second pilot valve 40, the first pressure receiving portion. 45 has meter-in aperture 6
The 3a upstream pressure, the load pressure of the actuator 6 (the downstream pressure of the meter-in throttle 63a) is guided to the second pressure receiving portion 46, and the control force in the direction of opening the flow path of the throttle portion 42 of the second pilot valve 40 together with the spring 50p. And the third
The maximum load pressure is guided to the pressure receiving portion 47, and the pressure of the back pressure chamber 70 is guided to the fourth pressure receiving portion 47, and a control force in the direction of restricting the flow path of the throttle portion 42 is applied.

Therefore, when the pump pressure is
Is not reached, the load pressure of the actuator 6 is guided to the outflow port 202 as the upstream pressure of the meter-in throttle 63a, and the load pressure separates the first pilot valve 30 and the second pilot valve 40, The first pilot valve 30 is seated on the seat portion 34 and shuts off the first flow path 22 in the main valve 20 and the inflow port 201. For this reason, the pressure in the third pressure receiving chamber 73 and the back pressure chamber 70 also becomes the load pressure of the actuator 6, and the main valve 20 is maintained at the shut-off position shown in the drawing, so that it can function as a so-called load check valve, and the outflow port 202 Backflow of pressurized oil can be prevented.

At this time, the same actuator 6 is provided in the first pressure receiving portion 45 and the fourth pressure receiving portion 48 of the second pilot valve 40.
The second pressure receiving portion 46 and the third pressure receiving portion 47
Since the same load pressure of the actuator 6 is guided to the second pilot valve 40, the second pilot valve 40 is maintained in the fully opened state in the drawing.

When the pump pressure reaches a pressure sufficient for driving the actuator 6, the first pilot valve 30 separates from the seat portion 34 to connect the inflow port 201 with the first flow path 22 and to release the first pilot valve 30. The pilot valve 30 is
The abutment with the pilot valve 40 moves together and the second
A control force for opening the flow path of the throttle portion 42 of the pilot valve 40 is applied. At this time, the inflow port 2
A pilot flow from 01 through the first flow path 22, the throttle 23, the back pressure chamber 70, and the throttle section 42 to the outflow port 202 through the second flow path 24 occurs. When the pressure drops, the main valve 20
1 and an outflow port 202 are opened.

When the main valve 20 opens in this manner, the flow path between the throttle portion 42 of the second pilot valve 40 and the seat portion 26 of the main valve 20 is throttled, and the pressure in the back pressure chamber 70 becomes The pressure is controlled to be higher than the pressure in the two flow paths 24 (the pressure in the outflow port 202). At this time, if the gap between the throttle portion 42 and the seat portion 26 becomes too small, the main valve 20 is closed by the pressure of the back pressure chamber 70. Since the main valve 20 is pushed back in the valve direction, the position of the main valve 20 is controlled so as to be balanced with a small gap with respect to the throttle portion 42 (described later).

On the other hand, at this time, the pump pressure is led to the pressure receiving portion on the first pressure receiving chamber 71 side of the first pilot valve 30 which is in contact with the first pressure receiving portion 45 of the second pilot valve 40. The pressure of the back pressure chamber 70 is guided to the fourth pressure receiving part 48, the load pressure of the same actuator 6 is guided to the second pressure receiving part 46 and the third pressure receiving part 47, and the pump pressure is changed to the back pressure chamber 70.
And the pressure in the back pressure chamber 70 is
2, the second pilot valve 40 is kept in the fully opened state in the drawing, and the main valve 20 is also fully opened.

Accordingly, the pressure oil subjected to the load sensing control of the hydraulic pump 1 flows into the actuator 6 via the inflow port 201, the pressure compensating valve 7, the outflow port 202, the meter-in throttle 63a of the direction switching valve 8, and the passage 9. ,
The return oil from the actuator 6 flows to the tank 5 via the passage 10 and the pressure compensating valve 8, and the actuator 6 can be extended and driven in an intended manner.

The above is a case where the actuator 6 is driven alone. At the time of a combined operation in which a plurality of actuators including the actuator 6 are simultaneously driven and the load pressure of the actuator 6 is higher than the load pressures of the other actuators, the maximum load pressure detected in the detection path 13 is the load of the actuator 6 The operation of the pressure compensating valve 7 is the same as that in the case of the single operation of the actuator 6.

In a combined operation in which a plurality of actuators including the actuator 6 are simultaneously driven and the load pressure of the actuator 6 is lower than the load pressure of the other actuator, the load pressure of the other actuator is supplied to the detection path 13. This is detected as the maximum load pressure, and the maximum load pressure is guided to the third pressure receiving portion 47 of the second pilot valve 40. The displacement of the hydraulic pump 1 is controlled by the load sensing control of the tilt control unit 2 so that the pump pressure is higher than the maximum load pressure by a fixed pressure. This pump pressure is applied to the first pressure receiving unit 45 of the second pilot valve 40. The first pilot valve 30 in contact
It is guided to the pressure receiving section on the pressure receiving chamber 71 side. On the other hand, at this time, the second
The pressure of the back pressure chamber 70 is guided to the fourth pressure receiving portion 48 of the pilot valve 40, and the load pressure of the actuator 6 is guided to the second pressure receiving portion 46. For this reason, when the differential pressure between the maximum load pressure and the load pressure of the actuator 6 is larger than the differential pressure between the pump pressure and the pressure in the back pressure chamber 70, the second pilot valve 40 operates as the first pilot valve.
The main valve 20 moves together with the pilot valve 30 in the direction to restrict the flow path of the throttle section 42 on the right side in the figure from the fully open state shown in the figure. The main valve 20 moves to reduce the opening degree of the main valve 20. In addition, the main valve 20
As a result, the pressure in the back pressure chamber 70 also decreases correspondingly, and the differential pressure between the maximum load pressure and the load pressure of the actuator 6 becomes the pump pressure and the back pressure chamber. When the pressure difference becomes smaller than the pressure difference from the pressure 70, the second pilot valve 40 moves integrally with the first pilot valve 30 in a direction to open the flow path of the throttle portion 42 on the left side in the figure, and The action also causes the main valve 20 to move in the valve opening direction following this, increasing the opening of the main valve 20. As a result, the first pilot valve 30 and the second pilot valve 40 balance at a position where the differential pressure between the maximum load pressure and the load pressure of the actuator 6 becomes equal to the differential pressure between the pump pressure and the pressure of the back pressure chamber 70,
The pump pressure is reduced so that the pressure of the outlet port 202 becomes higher than the load pressure of the actuator 6 by a pressure corresponding to the pump differential pressure related to the load sensing control.

Here, the operation of the pressure compensating valve 7 is controlled by the main valve 2
This will be described in more detail with reference to the equation for the balance between the 0, first and second pilot valves 30, 40.

The main valve 20, the first pilot valve 30, and the second
The balance of the pilot valve 40 is as follows (1) to (3)
It can be expressed by an equation.

The balance of the main valve 20 PsAs + PzAz = PcAc + ks (z + z0) (1) The force in the valve opening direction acting on the first pilot valve 30 Fp1 = Ap1 (Ps−Pz) (2) The second pilot valve Fp2 = Ap2 (PLmax−PL) + Ap1 (Pc−Pz) −kp (y + y0) (3) where Ps: discharge pressure of the hydraulic pump 1 Pc: pressure of the back pressure chamber 70 Pz : Upstream pressure of meter-in restrictor 63a or 63b PL: downstream pressure of meter-in restrictor 63a or 63b As: pressure receiving area on Ps pressure side (inflow port 201 side) of main valve 20 Ac: Pc pressure side of main valve 20 (back pressure chamber 70 side) ) Pressure receiving area Az: receiving area on Pz pressure side (outflow port 202 side) of main valve 20 As + Az = Ac (4) κ = As / Ac (5) κ: Pressure receiving area ratio between As and Ac Ap1 : Pressure receiving area of first pilot valve 30 Ap2: Pressure receiving parts 45, 46, 4 of the second pilot valve 40
7, 48 pressure receiving area kp: spring constant of spring 50p ks: spring constant of spring 50s y: displacement of second pilot valve 40 z: displacement of main valve 20 y0: preset amount of spring 50p z0: preset amount of spring 50s From the above equations (1), (4) and (5), the differential pressure Ps-Pz across the main valve 20 is divided and balanced as follows.

Ps−Pc = (1−κ) (Ps−Pz) (6) Pc−Pz = κ (Ps−Pz) (7) (However, the spring force term ks (z + z0) is ignored) That the first and second pilot valves 30 and 40 are in contact with each other means that the force in the valve opening direction and the force in the valve closing direction are balanced (Fp1 = Fp2), and (2)
From equation (3), Ap1 {(Ps-Pz)-(Pc-Pz)} = Ap2 (PLmax-PL) -kp (y + y0) Substituting equation (7), AP1 (1-.kappa.) (Ps- Pz) = Ap2 (PLmax-PL) -kp (y + y0) (8) Then, the pressure receiving area Ap2 of the pressure receiving portions 45 to 48 of the second pilot valve 40 is set as: Ap2 = Ap1 (1-κ) (9) Then, Ps−Pz = PLmax−PL−kp (y + y0) / Ap2∴Pz−PL = Ps−PLmax + kp (y + y0) / Ap2 ≒ ΔPLS (10) Therefore, the first pilot valve 30 comes into contact and operates integrally. The second pilot valve 40 is provided with a meter-in throttle 6
The throttle section 42 functions so that the front-rear differential pressure Pz-PL of 3a becomes equivalent to the pump differential pressure ΔPLS (= Ps-PLmax) related to the load sensing control, and the opening of the main valve 20 that moves following the control is controlled. Is done. In addition, since the differential pressure is similarly controlled by the meter-in throttle of the direction switching valve related to any of the actuators, the flow dividing function can be achieved.

Assuming that the gap between the throttle section 42 of the second pilot valve 40 and the seat section 26 that operates as described above is yao, the gap yao is obtained as follows.

Assuming that the flow rate of the throttle 23 is Qi and the flow rate of the throttle section 42 is Qo, from the continuous equation (Qi = Qo), Qi = C · ai√ (Ps−Pc) Qo = C · Kao (y −z) √ (Pc−Pz) where ai: opening area of the diaphragm 23 ao: opening area of the gap yao between the diaphragm part 42 and the sheet part 26 ao = Kao (yz) Kao: constant ∴yao = y− z = (ai / Kao) √ (Ps−Pc) / (Pc−Pz) = (ai / Kao) √ (1 κ) / κ = constant Therefore, the position of the main valve 20 is controlled so as to follow the displacement of the second pilot valve 40 with a small gap (a fixed distance) from the second pilot valve 40. Next, an embodiment in which the overall configuration of the direction switching valve device 251 including the pressure compensating valve 7 shown in FIG. 1 is applied to the two-way operation of the actuator 6 will be described with reference to FIGS. explain. In the figure, the main parts of the pressure compensating valve 7 are denoted by the same reference numerals as in FIG. 1, and these parts will not be described in detail to avoid duplication.

In FIG. 2, the pressure compensating valve 7 for controlling the opening and closing of the inflow port 201 and the outflow port 202 is provided in the casing main body 200 of the direction switching valve device 8. Hole 2
The spool 60 of the direction switching valve 8 is fitted into 00a. A signal port 101 and a meter import 102 are provided around the spool hole 200a in the casing body 200.
a, 102b, actuator ports 103a, 103
b, tank ports 104a and 104b are provided, and the meter import 102a is connected to the outflow port 202 of the pressure compensating valve 7 through the flow path 206, and the signal port 10
Reference numeral 1 is connected to the signal port 203 of the pressure compensating valve 7 via a flow path 207.

A flow path 105 connected to the actuator port 103a and a flow path 106 connected to the actuator port 103b are connected to the actuator 6 via respective actuator lines 9 and 10.

At each land of the spool 60, meter-in stops 63a and 63b and meter-out stops 64a and
4b, the meter-in aperture 63a connects the meter import 102a and the actuator port 103b, the meter-in aperture 63b connects the meter import 102b and the actuator port 103b, and the meter-out aperture 64a in conjunction with the operation of the spool 60. Is the actuator port 103a and the tank port 104a
The meter-out throttle 64b shuts off the actuator port 103b and the tank port 104b, respectively.
It is configured to communicate.

The spool 60 has axial oil holes 61 and 62 formed therein.
1a, 61b, and 61c have radial holes 6 in the oil holes 62.
2a, 62b, and 62c are formed in communication with each other.
The holes 61b and 62b are connected to the tank ports 104a and 104b, and the holes 61c and 62c are connected to the signal port 101 so as to be connected and disconnected according to the operation state of the spool 60.

Here, FIG. 3 is a cross-sectional view taken along a line III-III taken along a plane perpendicular to the paper passing through the center axis of the spool 60.

FIG. 3 shows a casing body 200 of a plurality of direction switching valve devices 252 including a direction switching valve device 251.
FIG. 3 is a cross-sectional view showing a state in which
The meter import 102a that communicates with the outflow port 202 through the port 06 is further configured to be connected to the other meter import 102b through the passage bridge 102c. Pressure compensation valve 7 in 63a or 63b
Spilled pressure oil from the pump. Further, the casing body 200 is provided with a main body 2 of another laminated directional control valve device.
A passage pocket 107 connected to the passage bridge 102c is formed so that a sufficient passage area can be secured while suppressing the thickness of the casing body 200.

Returning to FIG. 2, input signal ports (signal paths) 12a and 12b and output signal ports (output paths) 12c are formed in the casing body 200, and a shuttle valve 11 containing a check ball is provided. The signal path 12a is connected to the signal port 101 described above.

Here, FIG. 4 is a cross-sectional view taken along a line IV-IV cut from a central axis of the shuttle valve 11 through the signal port 101 and the signal port 203 of the pressure compensating valve 7 along a plane perpendicular to the paper.

FIG. 4 shows a plurality of directional control valve devices 252, 253, including a directional control valve device 251 similarly to FIG.
.. Are sectional views of a state in which the casing main bodies 200 are stacked. Large diameter oil holes 15a and 15b are formed coaxially on both back surfaces of the casing main body 200, and are parallel to the axis thereof, and these large diameters are formed. The small-diameter oil holes 14a and 14b are provided at the positions inside the oil holes 15a and 15b, respectively.
b, 12c, whereby the adjacent large-diameter oil holes 15a, 15b of the laminated casing main body 200 are continuously connected, thereby forming the illustrated staggered signal circuit. A large-diameter oil hole 15 communicating with the output port 12c of the shuttle valve 11 of the direction switching valve device 253 in which the casing body 200 is located at the lowest stage.
b is connected to the detection path 13 of the highest load pressure. Further, since the small-diameter oil holes 14a and 14b are provided via the large-diameter oil holes 15a and 15b, the processing of the signal passage can be simplified and a sufficient passage area of the signal passages 14a and 14b can be secured.

The operation of the directional control valve device configured as described above will be described.

In FIG. 2, for example, when the spool 60 is switched to the left in the figure, the hydraulic oil of the hydraulic pump 1 passes through the inflow port 201, the meter-in throttle 63 a of the spool 60 via the pressure compensating valve 7, and the actuator line 9. It flows into the actuator 6 and returns from the actuator 6 to the tank port 104b via the actuator line 10 and the meter-out throttle 64b. At the same time, the downstream pressure of the meter-in throttle 63a is guided to the signal port 101 as a self-load pressure through the small hole 61a, the oil hole 61, and the small hole 61c in the spool 60, and this pressure is applied to the signal port of the pressure compensating valve 7. 203, further guided to the input port 12a of the shuttle valve 11, and
The maximum load pressure related to load sensing is detected in the detection path 13 by the signal circuit of the hydraulic pump 1, the hydraulic pump 1 has a discharge capacity controlled by load sensing, and the pressure compensating valve 7
, The actuator can be driven with the above-described pressure compensation (shunting) control.

For example, when the spool 60 is switched to the right in the figure, the pressure oil of the hydraulic pump 1 is supplied to the inflow port 2.
01, flows into the actuator 6 via the meter-in throttle 63b of the spool 60 via the pressure compensating valve 7 and the actuator line 10, and is returned from the actuator 6 to the tank port 104a via the actuator line 9 and the meter-out throttle 64a. At the same time, the downstream pressure of the meter-in throttle 63b is applied as a self-load pressure through the pores 62a, the oil holes 62, and the pores 62c in the spool 60.
1, and this pressure is applied to the signal port 203 of the pressure compensating valve 7 and the input port 12a of the shuttle valve 11.
The maximum load pressure related to load sensing is detected in the detection path 13 by the signal circuit of the series of shuttle valves 11 described above, and the discharge capacity of the hydraulic pump 1 is controlled by load sensing. Since it is guided to the port 204, the actuator can be driven with the above-described pressure compensation (shunting) control.

When the operation of the spool 60 is neutral,
The signal port 101 has a fine hole 61c, an oil hole 61, and a fine hole 61b.
To the tank port 104a, and to the tank port 104b through the fine holes 62c, the oil holes 62, and the fine holes 62b, so that the input port 12a of the shuttle valve 11 becomes the tank pressure and only the direction switching valve 8 An unload state is set, and therefore, the directional control valve 8 is not involved in load sensing control.

As described above, in the directional control valve device according to the first embodiment of the present invention shown in FIGS. 1 and 2, pressure is compensated (divided) by the before-orifice type pressure compensating valve 7.
The control function and the load check function can be performed, and the main valve 20 and the first pilot valve 30 of the pressure compensating valve 7 are constituted by poppet valves, so that the load check function with less leakage can be performed. Further, since the pressure compensating valve 7 is of a before orifice type, the spool 60 of the direction switching valve 8 has a simple structure in which the land portion having the meter-in throttles 63a and 63b also serves as the direction switching portion. By providing the passage pocket 107 on the road, the casing body 20
0 can be made thin, and the signal path is composed of a combination of the small-diameter oil holes 14a, 14b and the large-diameter oil holes 15a, 15b.
The signal path is also simplified, and the valve device can be small and have an excellent leakage prevention function.

FIG. 5 is a view showing the configuration of a directional control valve device with pressure compensation according to a second embodiment of the present invention, together with a hydraulic circuit. In the drawing, parts equivalent to those in FIG. And the description is omitted.

In FIG. 5, reference numeral 250B denotes the entire directional switching valve device with pressure compensation of the present embodiment, and a directional switching valve device having a pressure compensating valve 7B as one of a plurality of unit valves of the directional switching valve device 250B. 251B are provided. Here, the difference between the pressure compensating valve 7B and the pressure compensating valve 7 in FIG. 1 is that, of the pressures acting on the second pilot valve 40B, one of the pressures for applying the control force in the valve closing direction is changed to the back pressure. That is, the pressure on the upstream side of the meter-in throttle is set based on the pressure of the chamber 70.

That is, the second pilot valve 40 B of the pressure compensating valve 7 B is provided with an axial oil hole 41 opened at the end of the stem 43.
B, a sixth pilot valve formed between the plug 53 and the piston shaft portion 44 a on the side of the second pilot valve 40 opposite the back pressure chamber 70.
The pressure receiving chamber 76 communicates with the third pressure receiving chamber 73 through the oil hole 41B, and the fourth pressure receiving section 48 restricts the pressure of the third pressure receiving chamber 73 in the direction of restricting the flow path of the throttle section 42 (the direction of the main valve 20). (The direction of closing the valve).

The other parts, such as the main valve 20 for communicating and shutting off the inflow port 201 and the outflow port 202 and the first pilot valve 30 in the main valve 20, are the first pilot valve 30.
Pressure receiving area Ap1 and the piston 4 of the second pilot valve 40B
Except for the relationship of the pressure receiving area Ap2 of the pressure receiving portions 45, 46, 47, and 48 of 1B (described later), the arrangement and connection configuration is the same as that of FIG.

In the direction switching valve device 251B including the pressure compensating valve 7B configured as described above, when the discharge pressure of the hydraulic pump 1 does not reach a pressure at which the actuator 6 can be driven, as in the first embodiment, 1st pilot valve 3
The main valve 20 and the main valve 20 are kept at the illustrated shut-off position, a load check function is performed, and backflow of the pressure oil from the outflow port 202 can be prevented.

When the pump pressure reaches a pressure sufficient to drive the actuator 6, the first pilot valve 30 separates from the seat portion 34 to connect the inflow port 201 with the first flow path 22 and to release the first pilot valve 30. The pilot valve 30 is
The second pilot valve 40B contacts the pilot valve 40B and moves as a unit, thereby applying a control force in the direction of opening the flow path of the throttle section 42 of the second pilot valve 40B. At this time, the outflow port 202 from the inflow port 201 through the first flow path 22, the throttle 23, the back pressure chamber 70, and the throttle section 42 via the second flow path 24.
, The pressure in the back pressure chamber 70 decreases due to the pressure drop by the throttle 23, and the main valve 20 operates to open the communication between the inflow port 201 and the outflow port 202.

Here, similarly to the first embodiment, the operation of the pressure compensating valve 7B will be described using the equation of the balance between the main valve 20, the first and second pilot valves 30, 40B. The balance can be expressed by the above equation (1), the force in the valve opening direction acting on the first pilot valve 30 can be expressed by the above equation (2) (represented below), and the force in the valve closing direction acting on the second pilot valve 40B. Fp2B can be expressed by the following equation (3 ').

The force in the valve opening direction acting on the first pilot valve 30 Fp1 = Ap1 (Ps−Pz) (2) The force in the valve closing direction acting on the second pilot valve 40B Fp2B = Ap2 (PLmax−PL ) -Kp (y + y0) (3 ') Here, the fact that the first and second pilot valves 30, 40B are in contact with each other means that Fp1 = Fp2B, and (2), (3') From the equation, Ap1 (Ps-Pz) = Ap2 (PLmax-PL) -kp (y + y0) (8 ') Then, the pressure receiving area Ap2 of the pressure receiving portions 45 to 48 of the piston 44B of the second pilot valve 40B is given by Ap2 = Ap1. .. (11) Pz−PL = Ps−PLmax + kp (y + y0) / Ap2 ≒ ΔPLS (10 ′) Therefore, the second pilot valve 40B which the first pilot valve 30 abuts and operates integrally is Of meter-in aperture 63a or 63b The throttle section 42 of the second pilot valve 40B functions so that the front-rear pressure difference Pz-PL becomes equivalent to the pump pressure difference ΔPLS (= Ps-PLmax) related to the load sensing control, and the main valve 20 that moves following the pressure difference. The opening is controlled. Further, since the differential pressure is similarly controlled by the meter-in throttle of the direction switching valve relating to any of the actuators, FIG.
The flow dividing function can be achieved similarly to the embodiment.

FIG. 6 shows an embodiment similar to FIG. 2 showing the entire configuration of a direction switching valve device 251B provided with the pressure compensating valve 7B shown in FIG.
Instead of using the pressure compensating valve 7B of FIG. 5, the configurations of the main body casing 200, the spool 60, and the like are the same as those of the embodiments of FIGS. 2, 3, and 4, and these portions are denoted by the same reference numerals. It is attached.

In the direction switching valve device of this embodiment,
The before-orifice-type pressure compensating valve 7B can perform the same pressure compensation (shunting) control function and load check function with little leakage as in the first embodiment,
The configuration of the valve 00 and the spool 60 is the same as that of the first embodiment, so that the valve device can be downsized.

FIG. 7 is a view similar to FIG. 6, showing a directional control valve device with pressure compensation according to a third embodiment of the present invention in which the pressure compensation valve shown in FIG. 5 is modified. 1 to
Parts that are the same as those shown in FIG. 6 are given the same reference numerals, and descriptions thereof will be omitted.

In FIG. 7, reference numeral 251C denotes a directional switching valve device with pressure compensation as a unit valve of this embodiment, and the directional switching valve device 251C is provided with a pressure compensating valve 7C. The difference between the pressure compensating valve 7C and the pressure compensating valve 7B of FIG. 5 is that the pressure receiving area relationship (Ap2 = Ap1) of the above-described equation (11) is focused on, and among the pressures acting on the second pilot valve 40C, That is, the respective pressures for applying the control force in the valve closing direction are exchanged.

That is, the signal port 204 of the pressure compensating valve 7C of the present embodiment is connected to the meter import 1 through the flow path 208.
02b of the control pressure in the valve closing direction of the second pilot valve 40C of the pressure compensating valve 7C.
The pressure at the outflow port 202 of the main valve 20, which is the upstream pressure of 3a or 63b, does not come from the oil hole 41B in the second pilot valve 40B of FIG. , The meter import 102a, the passage bridge 102c having a cross section taken along the line III-III shown in FIG. 3, the meter import 102b, the flow passage 208, and the signal port 204, and the second pilot valve 40C through the hole 55 of the plug 52. The third pressure receiving portion 47 receives a pressure. Around the plug 52 in the casing body 200, in addition to the signal ports 203 and 204, the signal port 2
09 is formed, and the sixth pressure receiving chamber 76 communicates with the signal port 209 through the hole 56 of the plug 52. The maximum load pressure by the detection path 13 is guided to the signal port 209, and the plug 5
Pressure is applied to the fourth pressure receiving portion 48 of the second pilot valve 40C via the second hole 56.

Here, since the signal path 208 is provided in the casing body 200 as described above, the second pilot valve 40C has an oil hole 41 or 41 in the second pilot valve 40C.
B becomes unnecessary, and the pressure receiving areas of the pressure receiving portions 45 to 48 of the second pilot valve 40C are determined by the relationship Ap2 =
Designed with Ap1.

As in the above embodiment, the operation of the pressure compensating valve 7C is controlled by the main valve 20, the first and second pilot valves 30, 40.
The balance of the main valve 20 can be expressed by the above equation (1). The force Fp1 in the valve opening direction acting on the first pilot valve 30 and the valve closing acting on the second pilot valve 40C will be described. The directional force Fp2B can be expressed by the following equations (2 ') and (3').

The force in the valve opening direction acting on the first pilot valve 30 Fp1 = Ap1 (Ps−Pz) = Ap2 (Ps−Pz) (2 ′) In the valve closing direction acting on the second pilot valve 40C Force Fp2C = Ap2 (PZ-PL) + Ap1 (PLmax-Pz) -kp (y + y0) = Ap2 (PLmax-PL) -kp (y + y0) (3 ') The first and second pilot valves 30, 40C are in contact. That is, it means that Fp1 = Fp2C. From the equations (2 ') and (3'), Pz-PL = Ps-PLmax + kp (y + y0) /Ap22.DELTA.PLS (10 ') The second pilot valve 40C, which the pilot valve 30 abuts and integrally operates, converts the differential pressure Pz-PL between the meter-in throttle 63a and 63b into a pump differential pressure ΔPLS (= Ps-PLmax) corresponding to the load sensing control. So that the second pilot valve 4 C of the aperture portion 402
Functions, and the opening of the main valve 20 that moves following this is controlled. Further, since the differential pressure is similarly controlled by the meter-in throttle of the direction switching valve relating to any of the actuators, the flow dividing function can be achieved similarly to the above-described embodiment.

As described above, in the present embodiment in which the signal path 208 and the signal port 209 are provided in the casing main body 200, the pressure compensation (diversion) control function and the load check function with little leakage similar to the first embodiment are provided. The structure of the main body casing 200 and the spool 60 is the same as that of the first embodiment, so that the valve device can be downsized.

FIG. 8 is a view similar to FIG. 7 showing the structure of a directional control valve apparatus with pressure compensation according to a fourth embodiment of the present invention, in which parts equivalent to those shown in FIG. Are denoted by the same reference numerals and description thereof is omitted.

In FIG. 8, the pressure compensating valve 7D of the direction switching valve device 251D of the present embodiment has a constant differential pressure type pressure compensating function (no diversion function) and a load check function. The difference from the illustrated pressure compensating valve 7C is that the discharge pressure of the hydraulic pump 1 is guided to the signal port 209 via the signal path 16 and the pump pressure is guided to the sixth pressure receiving chamber 76 via the hole 56 of the plug 52. 4th of pilot valve 40C
The pressure receiving section 48 is caused to receive a pressure as a control force in the valve closing direction, and the initial urging force of the spring 50Dp is closed according to a predetermined differential pressure equivalent to the differential pressure across the meter-in throttles 63a and 63b (target differential pressure). This is a configuration in which the control force is applied as a direction control force. Main valve 20 and first pilot valve 3
The connection configuration of the signal pressure in other parts such as 0, and the configuration of the casing body 20, the spool 60, and the like are the same as those in FIG.

As in the above embodiment, the operation of the pressure compensating valve 7D is controlled by the main valve 20, the first and second pilot valves 30, 40.
Explaining using the balance formula of C, the balance of the main valve 20 can be expressed by the above formula (1), and the force in the valve opening direction acting on the first pilot valve 30 is expressed by the above formula (2) (represented below). The force F acting on the second pilot valve 40C in the valve closing direction
p2D can be expressed by the following equation (3 ″).

The force in the valve opening direction acting on the first pilot valve 30 Fp1 = Ap1 (Ps−Pz) (2) The force in the valve closing direction acting on the second pilot valve 40C Fp2D = Ap2 (Pz−PL) ) + Ap1 (Ps-P2) -kp (y + y0) (3 ″) The fact that the first and second pilot valves 30, 40C are in contact with each other means that Fp1 = Fp2D, and (2), ( From equation 3 ″), Pz−PL = kp · y0 (1 + y / y0) / Ap2 ≒ ΔPo (12) (The pressure receiving areas Ap1 and Ap2 of the first and second pilot valves 30 and 40C of the pressure compensating valve 7D) In FIG.
The relationship Ap2 = Ap1 in the equation (11) in (or FIG. 6) may not be satisfied. Therefore, the load check function can be performed by the first pilot valve 30 and the main valve 20, and the second pilot valve 40C, which the first pilot valve 30 comes into contact with and operates integrally, is a differential pressure across the meter-in throttle 63a or 63b. The second pilot valve 40C is set so that Pz-PL is equivalent to the set constant differential pressure ΔPo which is initially biased by the spring 50Dp.
Of the main valve 20 that moves to follow this function is controlled, whereby the function of the constant differential pressure type pressure compensating valve is changed to the variable differential pressure type pressure compensating valve in the embodiment of FIG. It can be provided with a common component configuration.

Therefore, according to the present embodiment, the before-orifice-type pressure compensating valve 7D can perform a constant differential pressure type pressure compensating control function and a load checking function with less leakage. This is the same as the first embodiment, and the valve device can be downsized. Further, since the pressure compensating valve of the variable differential pressure type in the embodiment of FIG. 7 can be provided with a common component configuration, the manufacturing cost can be reduced.

FIG. 9 is a diagram showing a configuration of a directional control valve device with pressure compensation according to a fifth embodiment of the present invention, together with a hydraulic circuit. In the drawing, the same parts as those in FIG. And the description is omitted.

In FIG. 9, reference numeral 250E denotes the entire directional switching valve device with pressure compensation according to the present embodiment, and a directional switching valve device having a pressure compensating valve 7E as one of a plurality of unit valves of the directional switching valve device 250E. 251E are provided. Here, the difference between the pressure compensating valve 7E and the pressure compensating valve 7 in FIG. 1 is that the positional relationship between the inflow port and the outflow port is reversed.
That is, the form of the outflow flow from the main valve of the pressure compensating valve that communicates and shuts off these ports is changed from a wide flow to a narrow flow.

That is, the main valve 20E of the pressure compensating valve 7E is fitted into the cylinder chamber 200b in the casing body 200, and the back pressure chamber 7 between the rear surface of the main valve 20E and the plate 51 is inserted.
On the side close to 0, an inflow port 201E connected to the parallel pipeline 4 of the hydraulic pump 1 is provided. On the side far from the back pressure chamber 70, an outflow port 202E connected to the meter-in throttles 63a, 63b of the direction switching valve 8 is provided. The inflow port 201E and the outflow port 202E are shut off or communicated with each other by a seat portion 85 at the end of the main valve 20E. In this case, when the inflow port 201E and the outflow port 202E are in communication with each other, an outflow flow form generally referred to as a narrow flow occurs along the seat portion 85 of the main valve 20E.

The radial passage 8 is provided in the valve body of the main valve 20E.
7, an axial valve hole 81 having one end communicating with the inflow port 201E and the other end communicating with the back pressure chamber 70;
01E and the first pressure passages 82 a and 82 b for communicating the back pressure chamber 70 with the back pressure chamber 70 via the throttle 83, the back pressure chamber 70 and the outflow port 20.
A second flow path 84 is formed, which communicates 2E with the valve hole 81 via an opening on the back pressure chamber 70 side.

Further, the first pilot valve 3 is provided in the valve hole 81.
No. 0 poppet valve element is inserted, and the end portion 31 of the first pilot valve 30 is inserted into the hole portion of the valve hole 21 on the flow path 87 side in the radial direction.
A stepped portion having a seat portion 34 capable of seating is formed, and a portion between the flow 87 in the radial direction of the inflow port and the first flow passage 82a in the valve hole 81 is formed into a first pressure receiving chamber 71 and a second pressure receiving chamber 72. Divided. Further, the first pilot valve 30 disconnects the first flow path 82 a and the second flow path 84 in the valve hole 81 and
A third pressure receiving chamber 73 is formed in an opening portion of the second flow path 84 in the inside.

The pressure of the inflow port 201E is changed to the outflow port 2
When the pressure is lower than the pressure of 02E, the first pilot valve 30 is seated on the seat portion 34 (blocking position), and the first flow path 82a,
When the pressure of the inflow port 201E becomes larger than the pressure of the outflow port 202E, the fluid is separated from the sheet portion 34 (open position), and the inflow port 201E and the first flow paths 82a and 82b are blocked.
And communicate with. In the latter open position, the other end 32 of the first pilot valve 30 abuts against one end of the second pilot valve 40 to apply a control force in the valve opening direction to the second pilot valve 40, and 30 and the second pilot valve 40
Work together.

Therefore, even in the combination of the main valve 20E of the pressure compensating valve 7E and the first pilot valve 30 in this embodiment, the main valve 20 and the first valve of the pressure compensating valve 7 in the first embodiment shown in FIG. A function equivalent to the combination of the pilot valve 30 can be performed.

The construction relating to the second pilot valve 40 is the first
This is the same as the embodiment.

In the direction switching valve device 251E including the pressure compensating valve 7E configured as described above, when the discharge pressure of the hydraulic pump 1 does not reach the pressure at which the actuator 6 can be driven, as in the first embodiment, 1st pilot valve 3
The main valve 20E and the main valve 20E are maintained at the illustrated shut-off position, a load check function is performed, and backflow of the pressure oil from the outflow port 202E can be prevented.

When the pump pressure reaches a pressure sufficient for driving the actuator 6, the first pilot valve 30 separates from the seat portion 34, and connects the inflow port 201E with the first flow paths 82a and 82b. The first pilot valve 30 abuts on the second pilot valve 40 and moves integrally therewith, thereby giving a control force in the direction of opening the flow path of the throttle portion 42 of the second pilot valve 40. At this time,
From the inflow port 201E, the throttle 83, the first flow paths 82a, 82
2b, a backflow chamber 70, a pilot flow reaching the outflow port 202E via the second flow path 84 via the throttle section 42,
The pressure in the back pressure chamber 70 decreases due to the pressure drop by the throttle 83,
The main valve 20E has an inflow port 201E and an outflow port 202.
A valve opening operation is performed so as to communicate with E.

Here, similarly to the first embodiment, the operation of the pressure compensating valve 7E will be described using the equation of the balance between the main valve 20E and the first and second pilot valves 30, 40. The balance can be expressed by the above equation (1), the force in the valve opening direction acting on the first pilot valve 30 can be expressed by the above equation (2) (represented below), and the force in the valve closing direction acting on the second pilot valve 40. Fp2E can be expressed by the following equation (3 ^* ).

The force in the valve opening direction acting on the first pilot valve 30 Fp1 = Ap1 (Ps−Pz) (2) The force in the valve closing direction acting on the second pilot valve 40 Fp2E = Ap2 (PLmax−PL ) + Ap1 (Pc-Pz) -kp (y + y0) (3 ^* ) And, as in the first embodiment, the pressure receiving area Ap2 of the pressure receiving portions 45 to 48 of the second pilot valve 40 is Ap2 = Ap1 (1-κ). (9) Pz−PL = Ps−PLmax + kp (y + y0) / Ap2 ≒ ΔPLS (10) Therefore, the second pilot valve 40 that the first pilot valve 30 contacts and operates integrally is Meter-in aperture 6
The throttle section 42 of the second pilot valve 40 functions so that the pressure difference Pz-PL between the front and rear 3a or 63b becomes equivalent to the pump pressure difference ΔPLS (= Ps-PLmax) related to the load sensing control, and moves following the pressure difference. The opening of the main valve 20E is controlled. Further, since the differential pressure is similarly controlled by the meter-in throttle of the direction switching valve relating to any of the actuators, FIG.
The flow dividing function similar to that of the embodiment can be achieved by the narrow flow pressure compensating valve 7E of the present embodiment.

FIG. 10 shows the overall configuration of a direction switching valve device 251E provided with the pressure compensating valve 7E shown in FIG.
9 shows an embodiment similar to that shown in FIG. 9 except that a pressure compensating valve 7E shown in FIG. 9 is used instead of the pressure compensating valve 7 shown in FIG.
The configuration of the main body casing 200, the spool 60, etc. is shown in FIG.
This is the same as the embodiment of FIGS. 3 and 4, and these portions are denoted by the same reference numerals.

In the direction switching valve device of the present embodiment,
The before-orifice-type pressure compensating valve 7E can perform the same pressure compensating (shunting) control function and load checking function with little leakage as in the first embodiment,
The configuration of the valve 00 and the spool 60 is the same as that of the first embodiment, so that the valve device can be downsized.

Further, as is clear from the above description, even if the form of the outflow from the main valve of the pressure compensating valve is a narrow flow, the operation, function and effect are the same as those of the wide flow. Therefore, in the same manner as in the change of the main valve of the pressure compensating valve from the expanding flow in FIGS. 1 and 2 to the narrowing flow in FIGS. 9 and 10, FIGS. 5 and 6, and also FIGS. It will also be apparent that a change to a constricted flow configuration using the main valve 20E is possible.

[0109]

According to the present invention, the pressure compensation valve of the before orifice type can perform the pressure compensation control function and the load check function with less leakage, and the valve device can be downsized by taking advantage of the before orifice type.

[Brief description of the drawings]

FIG. 1 is a diagram showing the structure of a pressure compensating valve of a directional control valve device with pressure compensation according to a first embodiment of the present invention, together with a hydraulic circuit.

FIG. 2 is a diagram showing an embodiment of the entire structure of a directional switching valve device including the pressure compensating valve shown in FIG.

FIG. 3 is a sectional view taken along line III-III of FIG. 2;

FIG. 4 is a sectional view taken along line IV-IV of FIG. 2;

FIG. 5 is a diagram showing a structure of a pressure compensating valve of a directional switching valve device with pressure compensation according to a second embodiment of the present invention, together with a hydraulic circuit.

6 is a diagram showing an embodiment of the entire structure of the directional switching valve device provided with the pressure compensating valve shown in FIG.

FIG. 7 is a view showing the entire structure of a directional control valve device with pressure compensation according to a third embodiment of the present invention.

FIG. 8 is a diagram showing an entire structure of a directional control valve device with pressure compensation according to a fourth embodiment of the present invention.

FIG. 9 is a diagram showing a structure of a pressure compensating valve of a directional control valve device with pressure compensation according to a fifth embodiment of the present invention, together with a hydraulic circuit.

10 is a diagram showing an embodiment of the entire structure of the directional control valve device provided with the pressure compensating valve shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Variable displacement hydraulic pump 2 Tilt control part 3 Discharge pipeline 4 Parallel oil path 5 Tank 6 Actuator 7 Pressure compensating valve 8 Direction switching valve 8a, 8b, 8c Signal path 9, 10 Actuator line 11 Shuttle valve 12a, 12b Road (input port) 12c Output path (output port) 13 Detection path 14a, 14b Small diameter oil hole 15a, 15b Large diameter oil hole 20 Main valve 21 Valve hole 22 First flow path 23 Restrictor 24 Second flow path 25 Seat 26 Seat part 30 First pilot valve 31 Seat part 32 End part 33 Plug 34 Seat part 40 Second pilot valve 41 Oil hole 42 Throttle part 43 Stem part 44 Piston 44a Piston shaft part 45 First pressure receiving part 46 Second pressure receiving part 47 First 3 pressure receiving portion 48 4th pressure receiving portion 50p spring 50s spring 51 plate 52 plug 52 plug 53 plug 54 hole 55 hole 60 spool 61 first oil hole 61a, 61b, 61c fine hole 62 second oil hole 62a, 62b, 62c fine hole 63a, 63b meter-in throttle 64a, 64b meter-out throttle 70 back pressure chamber 71 first pressure receiving chamber 72 first 2 pressure receiving chamber 73 third pressure receiving chamber 74 fourth pressure receiving chamber 75 fifth pressure receiving chamber 76 sixth pressure receiving chamber 101 signal port 102a, 102b meter import 102c passage (bridge) 103a, 103b meter out port 104a, 104b tank port 105 flow path 106 flow path 107 flow path (pocket) 200 casing body 200a spool hole 200b cylinder chamber 201 inflow port 202 outflow port 203 signal port 204 signal port 205 flow path 206 flow path 207 flow path 250 direction switching valve device 251 direction switching valve device ( 7B ... pressure compensating valve 7D ... pressure compensating valve 7E ... pressure compensating valve 16 ... signal path 56 ... hole 208 ... flow path 209 ... signal port 40B ... second pilot valve 40C ... second pilot valve 41B ... oil hole 44B ... piston 50Dp 250B directional switching valve device 251B directional switching valve device (unit valve) 251C directional switching valve device (unit valve) 251D directional switching valve device (unit valve) 250E directional switching valve device 251E directional switching valve device (Unit valve)

Claims (6)

[Claims] A variable displacement hydraulic pump, and a plurality of actuators driven by hydraulic oil of the hydraulic pump. A maximum load pressure among the load pressures of the plurality of actuators is detected to detect the maximum load pressure of the hydraulic pump. It is provided for each actuator of the hydraulic system that performs load sensing control that controls the discharge capacity of the hydraulic pump so that the discharge pressure is higher than its maximum load pressure by a predetermined value. In a directional switching valve device with pressure compensation for controlling a flow rate of pressure oil supplied from a hydraulic pump to a corresponding actuator with a pressure compensating valve located, the pressure compensating valve is connected to a discharge path of the hydraulic pump. A casing body having an inflow port and an outflow port connected to the variable throttle; A main valve consisting of a poppet valve body that communicates and shuts off the inlet port and the outlet port; a back pressure chamber formed in the casing body at the back of the main valve; and the inlet port, the back pressure chamber, and the outlet port. Pilot valve means for controlling the flow of the pressure oil to reach and change the fluid pressure in the back pressure chamber to operate the main valve, wherein the pilot valve means controls at least the upstream pressure and the downstream pressure of the meter-in variable throttle. Directly or indirectly, when the discharge pressure of the hydraulic pump is lower than the load pressure of the actuator, the load pressure is led to the back pressure chamber to hold the main valve in the shut-off position, and the discharge pressure of the hydraulic pump When the pressure becomes higher than the load pressure of the actuator, the pressure in the back pressure chamber is reduced to open the main valve, and the pressure difference before and after the variable throttle of the meter-in is controlled. Direction switching valve apparatus. 2. The directional control valve device with pressure compensation according to claim 1, wherein the main valve is formed inside the main valve, and communicates with the back pressure chamber and the inflow port via a throttle. A second flow path formed inside the main valve and communicating the back pressure chamber and the outflow port; and a valve hole formed inside the main valve and open at both ends of the inflow port and the back pressure chamber. The pilot valve means comprises: a first pilot valve comprising a poppet valve body disposed in a valve hole of the main valve;
A second pilot valve configured separately from the pilot valve and arranged on the back pressure chamber side, wherein the first pilot valve has a pressure of the inflow port and a pressure of the outflow port through the second flow path. A pressure acts in opposition in the axial direction to connect the inflow port to the first flow path by contacting the second pilot valve with a first position for shutting off the inflow port and the first flow path. The second pilot valve restricts a flow path between the valve hole and an opening of the valve hole on the back pressure chamber side, and controls the back pressure. A throttle section for controlling the flow of pressure oil from the chamber to the second flow path; first and second pressure receiving sections for receiving pressure in a direction to open the flow path of the throttle section;
And third and fourth pressure receiving portions opposing the second pressure receiving portion and receiving pressure in a direction of restricting the flow path of the throttle portion, and flowing out to the first pressure receiving portion via the second flow path. Guide the pressure of the port, guide the downstream pressure of the meter-in variable throttle to the second pressure receiving portion, guide the pressure corresponding to the maximum load pressure and the discharge pressure of the hydraulic pump to the third pressure receiving portion, The directional control valve device with pressure compensation, wherein an upstream pressure of the meter-in variable throttle is guided to the fourth pressure receiving portion. 3. The directional control valve device with pressure compensation according to claim 2, wherein the second pilot valve is formed in the second pilot valve as an upstream pressure of a meter-in variable throttle guided to the fourth pressure receiving portion. A pressure-compensating directional switching valve device for guiding the pressure of the back pressure chamber through a defined internal passage. 4. The directional control valve device with pressure compensation according to claim 2, wherein the second pilot valve is formed in the second pilot valve as an upstream pressure of a meter-in variable throttle guided to the fourth pressure receiving portion. A pressure-compensated directional switching valve device for guiding the pressure of the outflow port through the internal passage and the second flow path. 5. The directional control valve device with pressure compensation according to claim 2, wherein the second pilot valve is formed in the casing main body as an upstream pressure of a meter-in variable throttle guided to the fourth pressure receiving portion. A directional switching valve device with pressure compensation, wherein the pressure on the inlet side of the variable throttle is guided through a flow path. 6. The directional control valve device with pressure compensation according to claim 2, wherein the main valve and the first and second pilot valves are arranged coaxially. apparatus.