JPH10205502A - Hydraulic control valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a pressure control valve compact in a hydraulic control valve by making compact a part that has a function as a pressure compensation valve and functions as a pressure selecting valve for selecting the maximum pressure of the inlet pressure of each pressure compensation valve and as a pressure selecting valve for making each pressure compensation valve prevent the backflow and achieves these functions. SOLUTION: A compensation valve 20 has a movable piston 40 at the center and a movable sleeve 30 at the periphery. One end of the movable piston 40 faces a small room 24 communicating with the inlet port 14 of the compensation valve 20 and the other end thereof faces a LS pressure room 54 and is biased by a spring 43 to the direction of the inlet port 14 and has passages 41, 42 opened from the inlet port to the LS room only when moving to the LS pressure room 54. One end of the movable sleeve 30 faces the outlet port 15 of the compensation valve 20 and the other end thereof faces a LS pressure room 55 and is moved to a low pressure side when the outlet port or the LS pressure room becomes high pressure and has a passage 33 making the high pressure side communicate with a back pressure room 26.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control valve and, more particularly, to a pressure compensating valve used for a load sensing system for operating a plurality of actuators in a construction machine such as a hydraulic shovel, and for securing a flow dividing characteristic in a combined operation. The present invention relates to a hydraulic control valve provided.

[0002]

2. Description of the Related Art It is generally known that a load sensing system is used as a hydraulic drive for operating a plurality of actuators. Further, in this load sensing system, a hydraulic control valve provided with a pressure compensating valve is arranged in order to secure the flow dividing characteristic during the combined operation. FIG. 3 shows an example.

In FIG. 3, outlets of meter-in throttles 4 and 4a in a hydraulic control valve and actuators 10 and 10 are shown.
a pressure compensating valves 7 and 7a are respectively arranged between the passages
The outlet side pressures (inlet pressures of the pressure compensating valves) of the meter-in throttles 4 and 4a act on the pilot chambers 7-1 and 7-2 for operating the pressure compensating valves 7 and 7a in the opening direction. Chambers 7-3 and 7 for operating the airbags in the closing direction
-4, the LS pressure obtained from the maximum pressure selected by the pressure selection valves 8, 8a among the inlet pressures of the pressure compensating valves 7, 7a is applied, and the outlet side pressures of the meter-in throttles 4, 4a are always set to the same maximum pressure. The pressure is adjusted to near the LS pressure.

Here, the pressure selection valves 8 and 8a select the high pressure side (maximum pressure) of the inlet pressure of the pressure compensating valves 7 and 7a as the LS pressure.
Because it is connected to the tank 5 via 3b and the throttle 6,
When the pressure selection valve 8 or 8a opens, the pressure compensating valve 7 or 7a
A small amount of pressure oil flows from the inlet side to the tank 5 through the LS passages 13a and 13b and the throttle 6, and the LS passage 1 is caused by the throttle action by the passage resistance of the pressure selection valve 8 or 8a.
The pressure transmitted to 3a is a pressure slightly lower than the inlet pressure of the pressure compensating valve 7 or 7a. The degree of the pressure drop is set to be larger than the force (pressure conversion value) of the springs 8-1 and 8-2 of the pressure selection valve 8 or 8a, whereby the pressure selection valve 8 or 82a is kept open. The pressure slightly lower than the inlet pressure acts on the pilot chambers 7-3 and 7-4 of the pressure compensating valves 7, 7a as the LS pressure. For this reason, the pressure compensating valves 7, 7a are connected to the actuators 10, 1
0a is not operated, the pilot chambers 701, 7-
2 becomes higher than the LS pressure, and the pressure can be opened by this inlet pressure.

The LS pressure in the LS passage 13a is LS
The flow is also guided to the flow control valve 2 of the hydraulic pump 1 by the passage 13b, and the discharge pressure of the hydraulic pump 1 is obtained by always adding a set differential pressure to the LS pressure. Thereby, at the time of combined operation, regardless of the magnitude of the load pressure, the meter-in throttles 4, 4
Each actuator 1 has a branching ratio corresponding to the opening area of a.
0,10a can be activated.

In this embodiment, load check valves 11, 11a are further provided between the pressure compensating valves 7, 7a and the actuators 10, 10a. This is to prevent backflow when the actuators 10 and 10a are started in a state where a load holding pressure higher than the maximum pressure is applied. 3, 3a are pilot valves for operating the meter-in throttles 4, 4a, and 12 is a pump port line.

FIG. 4 shows another example. In this example,
The high pressure side of the LS pressure obtained by selecting the pressure selecting valves 8, 8a and the outlet pressure (load holding pressure) of the pressure compensating valves 7, 7a is further selected by the pressure selecting valves 9, 9a. 7a is acted on pilot chambers 7-3 and 7-4 which operate in the closing direction. As a result, the pressure compensating valves 7, 7a also perform the function of a load check valve (backflow preventing function), so that the pressure compensating valves 7, 7a and the actuators 10, 1 as in the example of FIG.
There is no need to provide the load check valves 11, 11a between 0a.

A known example of the valve device shown in FIG. 3 is, for example, DE38444405A1, and a known example of the valve device shown in FIG. 4 is, for example, DE38444.
00A1.

[0009]

As described above, in the hydraulic control valve shown in FIG. 3, the pressure compensating valves 7, 7a and the actuator 1
While the load check valves 11 and 11a are provided between 0 and 10a, in the conventional example of FIG. 4, there is no need to provide a load check valve in such a main passage.
Since it is sufficient to dispose the pressure selection valves 9 and 9a in the signal line, it can be seen that the size can be reduced as compared with that shown in FIG. However, in the hydraulic control valve of FIG. 4, the pressure compensating valves 7, 7a, the pressure selecting valves 8, 8a for selecting the maximum pressure of the inlet pressure of each of the pressure compensating valves 7, 7a, and the respective pressure selecting valves 8, 8a.
The LS passage 13a which guides the maximum pressure selected in the above as the LS pressure to the flow control valve 2 of the hydraulic pump 1, selects the maximum pressure of the LS passage 13a and the high pressure side of the outlet pressure of the pressure compensating valves 7, 7a and selects the pressure compensating valve. Many components such as the pressure selection valves 9 and 9a that act in the closing direction of the valves 7 and 7a and perform the backflow preventing function of the pressure compensating valves 7 and 7a are required. Needs to put these components together.

Here, when the hydraulic control valve shown in FIG. 4 is embodied, each component itself such as the pressure compensating valves 7, 7a, the pressure selecting valves 8, 8a, the pressure selecting valves 9, 9a is realized by a conventional technique. As it is possible, these three valves will generally be combined into a body. However, if the pressure compensating valves 7, 7a, the pressure selecting valves 8, 8a, and the pressure selecting valves 9, 9a are individually formed and combined as they are, the hydraulic control valve becomes large.

An object of the present invention is to provide a pressure selecting valve for selecting the maximum pressure of the inlet pressure of each pressure compensating valve and a pressure selecting valve for causing the pressure compensating valve to perform a backflow preventing function in addition to the function as a pressure compensating valve. It is an object of the present invention to provide a hydraulic control valve which has each of the functions described above and compactly integrates the parts which fulfill these functions.

[0012]

In order to achieve the above object, the present invention provides a meter-in throttle for controlling a flow rate of pressure oil supplied to an actuator, and a meter-in throttle disposed between an outlet side of the meter-in throttle and the actuator. And a pressure compensating valve provided in the vicinity of the LS pressure obtained from the highest pressure among the inlet pressures of the pressure compensating valves by each pressure compensating valve at the time of the combined operation of driving a plurality of actuators. (A) the pressure compensating valve has a spool, one end of the spool facing a compensating valve inlet port connected to the outlet side of the meter-in throttle, and the other end thereof. Is provided at the spool portion facing the back pressure chamber, and a seat portion and a throttle portion with the direction of the compensation valve inlet port closed in the spool portion on the one end side, and further, the spool portion in the axial direction of the spool is further provided. A movable piston is slidably inserted into the through hole, and a movable sleeve is slidably inserted into the outer peripheral portion on the other end side of the spool. (B) One end of the movable piston is connected to the compensation valve inlet port. The other end faces the LS pressure chamber into which the LS pressure is introduced, and the movable piston is provided with a passage allowing communication between the compensation valve inlet port and the LS pressure chamber when the movable piston moves toward the LS pressure chamber. (C) one end of the movable sleeve faces the compensation valve outlet port, the other end faces the LS pressure chamber, and When either the compensation valve outlet port or the LS pressure chamber becomes high in pressure and the movable sleeve moves to the low pressure side, the movable sleeve is provided with a passage for communicating the high pressure side to the back pressure chamber.

When a hydraulic circuit is formed by using a plurality of hydraulic control valves of the present invention configured as described above, the movable piston in the LS pressure chamber of each hydraulic control valve has the highest pressure among the pressures at the respective compensation valve inlet ports. The pressure is slightly reduced by the passage resistance of the movable piston, and is selectively introduced as the LS pressure. The pressure of the compensation valve inlet port acts on the spool of the pressure compensating valve in the opening direction, the pressure of the back pressure chamber acts on the closing direction, and the back pressure chamber has a movable sleeve connected to the compensation valve outlet port by the movable sleeve. The higher pressure of the chamber is selectively introduced. For this reason,
When the meter-in throttle is opened and the pressure at the compensation valve inlet port rises, the seat and throttle of the compensation valve spool open,
The pressure at the compensation valve inlet port is adjusted near the LS pressure.

When the actuator is started in a state in which a load holding pressure higher than the maximum pressure is applied, the load holding pressure (pressure at the compensating valve outlet port) is selectively introduced into the back pressure chamber by the movable sleeve. The seat of the valve spool is pressed in the closing direction to prevent backflow.

As described above, the compensating valve spool functions as a pressure compensating valve, the movable piston functions as a pressure selecting valve for selecting the maximum pressure of the inlet pressure of each pressure compensating valve, and the movable sleeve functions as a pressure compensating valve. Acts as a pressure selection valve that causes the valve spool to have a backflow prevention function.

Further, since the movable piston is inserted through the compensating valve spool and the movable sleeve is inserted into the outer peripheral portion of the compensating valve spool, the components compensating for the pressure compensating valve and the two kinds of pressure selecting valves are compactly assembled. The size of the pressure compensating valve is not increased, and the hydraulic control valve can be downsized.

[0017]

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

FIG. 1 is a sectional view showing a hydraulic control valve according to an embodiment of the present invention. In the figure, the same reference numerals are given to members equivalent to the members shown in FIG.

In FIG. 1, a spool 17 is inserted into a body 60, and the pressure oil discharged from the hydraulic pump 1 is direction-controlled with the movement of the spool 17. Then, the flow rate is controlled through the input port 14 and the actuator 10 is operated through the actuator port 10A. Actuator 10
Is discharged from the actuator port 10A to the tank 5 through the meter-out throttle 16.

This hydraulic control valve is equivalent to one actuator of the hydraulic control valve shown in FIG. 4. When a load sensing system for driving a plurality of actuators 10 and 10a as shown in FIG. One valve is used as a unit, and a plurality of flow control valves are superposed and arranged in a direction orthogonal to the paper surface. At this time, the pump port line 12 is connected to the meter-in throttle 4 of each hydraulic control valve, and the LS passage 13a is connected to the pressure compensating valve 7 of each flow control valve. In the following, the pressure compensating valve 7 of the flow control valve shown in FIG. 1 will be described assuming that there are a plurality of flow control valves.

The pressure compensating valve 7 has a spool (hereinafter referred to as a compensating valve spool) 20 disposed between the outlet side of the meter-in restrictor 4 and the actuator port 10A. 4 (pressure at the inlet port 14 of the pressure compensating valve 7) was applied to slightly reduce the maximum pressure of the inlet pressure (pressure at the inlet port 14) of each pressure compensating valve 7 in the LS passage 13a in the closing direction. The high pressure side of the pressure (described later) and the outlet pressure of the own pressure compensating valve 7 (the pressure of the outlet port 15) is applied, and the outlet side pressure of the meter-in throttle 4 is constantly adjusted to a plurality of actuators 1.
The pressure is adjusted near the maximum pressure of 0, 10a (see FIG. 4), and the pressure compensating valve 7 functions as a load check valve (backflow prevention function).

Further, the pressure of the LS passage 13a is further increased by LS
The LS pressure is also guided to the flow control valve 2 of the hydraulic pump 1 by the passage 13b, and the discharge pressure of the hydraulic pump 1 is controlled to always be a pressure obtained by adding a set differential pressure to the LS pressure.

As described above, during the combined operation, each actuator can be operated at a shunt ratio commensurate with the opening area of the meter-in throttle 4, regardless of the magnitude of the load pressure of the plurality of actuators 10 and 10a.

FIG. 2 shows the structure of the pressure compensating valve 7 in detail. The compensation valve spool 20 has a front end face facing the compensation valve inlet port 14, a rear end face facing the back pressure chamber 26, and a back pressure chamber 26.
Is constantly receiving a pressing force in the right direction in the figure (toward the entrance port 14).

The outer peripheral surface of the compensating valve spool 20 is slidably fitted on the front end surface side to the body 60 at the sliding portion 22.
The rear end face side is slidably fitted to the movable sleeve 30,
Further, the amount of movement of the spool 20 is regulated by the convex portion 52 of the flange 50 fixed to the body 60. The inlet port 14 and the outlet port 15 are communicated and blocked by a sheet part 23 provided on a spool 20, and the opening area thereof is adjusted by a throttle part 21 provided on a sliding part 22 on the front end face side.

An axial through hole 27 is formed at the center of the compensating valve spool 20, and a movable piston 40 is slidably inserted into the through hole 27.

The movable sleeve 30 is slidably fitted in a cylindrical gap between the body 60 and the outer peripheral surface of the spool 20 and a cylindrical gap between the body 60 and the outer peripheral surface of the flange projection 52. The front end face of the sleeve 30 is the outlet port 15
, The rear end face faces the LS pressure chamber 55, and the amount of movement of the movable sleeve 30 is regulated by the body 60 and the flange 50. A communication hole 33 that communicates the inner and outer circumferences of the sleeve is formed at the center of the movable sleeve 30, and always communicates the back pressure chamber 26 with the body partition chamber 56 located on the outer circumference of the movable sleeve 30. Grooves 32 are cut in the front and rear ends of the outer peripheral surface of the movable sleeve 30 in the axial direction within a range not communicating with the communication hole 33.
At the position where 0 has moved to the front end side, the body septum chamber 56 communicates with the rear end groove 32, and at the position where 0 has moved to the rear end side, the body septum room 56 communicates with the front end groove 32. ing.

The movable piston 40 is slidably inserted into the axial through hole 27 of the spool 20 and the axial hole 53 formed at the center of the flange convex portion 52, and one end thereof communicates with the compensation valve inlet port 14. The other end faces the LS pressure chamber 54 provided in the flange 50 so as to communicate with the LS pressure chamber 55. The movable piston 40 is moved rightward in the figure (in the direction of the inlet port 14) by the spring 43 located in the LS pressure chamber 54.
, The amount of movement is regulated by the inner wall of the flange projection 52 and the stopper 51 provided on the flange 50.

At the center of the movable piston 40, a hole 41 opened to the small chamber 24 in the spool 20 extends, and at the end, it opens to the outer peripheral surface of the movable piston 40 through the small hole 42. When the movable piston 40 abuts on the inner wall of the flange convex portion 52, the small hole 42
And is shut off from the LS pressure chamber 54, and is arranged so as to be located in the LS pressure chamber 54 when stroked from this position to the left in the drawing.

In the above description, the compensation valve spool 20
The effective pressure receiving area of the front end face and the rear end face of the movable piston 30 are substantially the same, the effective pressure receiving area of the front end face and the rear end face of the movable sleeve 30 are also substantially the same,
And the effective pressure receiving area in the LS pressure chamber 54 are substantially the same. The strength of the spring 25 is
Is set slightly lower than the strength.

Next, the operation of the hydraulic control valve configured as described above will be described.

(A) When all actuators are not operated First, all actuators 10 and 10a (see FIG. 4)
Is inactive, no pressure is generated because no pressure oil is supplied to the inlet port 14 of each pressure compensating valve 7. Movable piston 4
0 remains closed by the spring 43. Since the pressure oil in the LS pressure chamber 54 is discharged to the tank 5 through the small-diameter LS throttle 6, no pressure is generated in the LS pressure chamber 54. The back pressure chamber 26 is provided with its own outlet port 1 by the operation of the movable piston 30.
5 (load pressure of the actuator 10) is selected,
Working. Therefore, the compensation valve spool 20 is connected to the back pressure chamber 2
The function of the load check valve (backflow prevention function) is closed by the pressure of 6 and the force of the spring 25.

(B) When the actuator is not operated (other actuators are operated) When there is no output from the pilot valve 3 (see FIG. 4) related to the hydraulic control valve shown in FIG. No pressure builds up at port 14. At this time, assuming that the other actuator 10a (see FIG. 4) is operating, the pressure of the outlet port 15 (load pressure of the actuator 10) and the LS passage in the back pressure chamber 26 are actuated by the operation of the movable sleeve 30. 13 pressure (other actuators 10
LS obtained from the pressure at the inlet port of the pressure compensating valve related to a
The higher pressure side of pressure is selected and working. Therefore, the compensation valve spool 20 is closed by the pressure of the back pressure chamber 26 and the force of the spring 25, and fulfills the function of a load check valve (backflow prevention function). Further, since the movable piston 40 is also closed by the LS pressure and the force of the spring 43 and the LS pressure chamber 54 and the inlet port 14 are shut off, the load pressure of another actuator 10a escapes through the LS pressure chamber 54. There is no.

(C) When the actuator is operated alone The pressure oil supplied from the meter-in throttle 4 is output to the compensation valve inlet port 14 and the pressure starts to rise.
When the pressure of the spring 4 is higher than the sum of the LS pressure of the LS pressure chamber 54 and the force (pressure conversion value) of the spring 43 (in this case, the LS pressure is the tank pressure and the force of the spring 43), the movable piston 40 Moves against the force, the LS pressure chamber 54 and the inlet port 1
4 communicates through the hole 41 and the small hole 42, so that the pressure at the inlet port 14 is introduced into the LS pressure chamber 54. At this time,
Hole 41 and small hole 42, LS pressure chamber 5 from inlet port 14
4, 55, an extremely small amount of pressure oil flows to the tank 5 through the LS passage 13a and the throttle 6, and is introduced into the LS pressure chamber 54 by the throttle action due to the passage resistance of the holes 41 and the small holes 42. Is slightly lower than the pressure at the inlet port 14. LS pressure = pressure at inlet port−spring 43
The movable piston 40 is moved to a position where the force (pressure conversion value) is obtained. The pressure in the LS pressure chamber 54 is introduced to the flow control valve 2 of the hydraulic pump 1 through the LS passages 13a and 13b as the LS pressure. The hydraulic pump 1 adjusts the amount of tilt so as to discharge a pressure higher than the LS pressure by a set pressure, and the pressure at the compensation valve inlet port 14 further increases. This pressure is the pressure of the back pressure chamber 26 and the force of the spring 25 (pressure conversion value).
When it becomes larger, the compensating valve spool 20 moves to the left in the drawing, passes through the throttle 21 and the seat portion 23 and exits from the outlet port 15.
Pressure oil flows to operate the actuator 10.

Here, when the LS pressure introduced into the LS pressure chamber 54 becomes higher than the load pressure of the actuator 10, the LS pressure is selected and introduced into the back pressure chamber 26 by the movable sleeve 30. However, the LS pressure is slightly lower than the pressure at the inlet port 14 due to the restricting action due to the passage resistance of the holes 41 and the small holes 42 as described above. Further, as described above, the strength of the spring 25 is set slightly smaller than the strength of the spring 43. Therefore, the entrance port 1
4 moves the compensating valve spool 20 to the left in the drawing against the pressure of the back pressure chamber 26 and the force (pressure converted value) of the spring 25,
The compensation valve spool 20 can be opened. This is the same in the following composite operation.

Then, the pressure of the compensating valve inlet port 14 is continuously adjusted to the LS pressure as described above, and introduced from the LS pressure chamber 54 to the flow regulating valve 2 of the hydraulic pump 1 through the LS passages 13a and 13b. Further adjusts the amount of tilt so as to discharge a pressure higher than the LS pressure by a set pressure. Therefore, the pressure difference between the front and rear of the meter-in throttle 4 is kept substantially at the set pressure, so that a flow rate proportional to the opening of the throttle 4 is supplied to the actuator 10.

(D) At the time of combined operation (and when the load pressure of the other actuator is low) The movable piston 40 is closed by the pressure of the LS pressure chamber 54 and the force of the spring 43. Further, the LS pressure is set at the outlet port 15.
(Load pressure of the actuator 10)
The back pressure chamber 26 is provided with an outlet port 15 by a movable sleeve 30.
(Load pressure of the actuator 10) is selected and applied. Therefore, the compensation valve spool 20 remains closed until the pressure of the inlet port 14 becomes larger than the pressure of the back pressure chamber 26 (pressure of the outlet port 15) and the force of the spring 25 (pressure conversion value). Function (backflow prevention function).

When the pressure at the inlet port 14 rises and becomes larger than the pressure of the LS pressure chamber 54 and the force (pressure conversion value) of the spring 43, the movable piston 40 moves against the force of the spring 43, and the LS pressure chamber 54 And inlet port 14 are hole 41, small hole 42
The pressure at the inlet port 14 is
1. The pressure is slightly reduced by the passage resistance of the small hole 42 and introduced into the LS pressure chamber 54 as the LS pressure.
3b, it is introduced into the flow control valve 2 of the hydraulic pump 1.
The hydraulic pump 1 adjusts the tilt amount so as to discharge a pressure higher than the LS pressure by a set pressure. Accordingly, the pressure at the inlet port 14 further increases, and the compensation valve spool 20 is moved to the left in the drawing, and passes through the throttle 21 and the seat portion 23 to the outlet port 15 as in the case of the single operation (c). The pressurized oil flows and activates the actuator 10. Further, since the pressure difference before and after the meter-in throttle 4 is substantially maintained at the set pressure by adjusting the tilt amount by the LS pressure of the hydraulic pump 1, the throttle 4
Is supplied to the actuator 10.

At this time, as described in (e), the pressure compensating valve 7a related to the other actuator 10a
Is controlled to be slightly higher than the LS pressure by an amount corresponding to the force of the spring 25. As a result, the pressure at the inlet port 14 is close to the pressure at the inlet port 14 of the pressure compensating valve 7 (maximum). (Near load pressure). Therefore, regardless of the magnitude of the load pressure, the pressure at the inlet port of each pressure compensating valve is controlled to a pressure near the same maximum load pressure, so that each actuator is operated at a shunt ratio corresponding to the opening area of the meter-in throttle 4. be able to.

(E) During combined operation (and when the load pressure of the other actuator is high) In the LS pressure chamber 54, a pressure obtained by adjusting the pressure of the inlet port of the pressure compensating valve related to the other actuator 10a is introduced as the LS pressure. Have been. The movable piston 40 is closed by the pressure of the LS pressure chamber 54 and the force of the spring 43. Further, since the LS pressure is higher than the pressure of the outlet port 15 (the load pressure of the actuator 10), the LS pressure is selected and applied to the back pressure chamber 26 by the movable sleeve 30.
Therefore, the compensation valve spool 20 remains closed until the pressure at the inlet port 14 becomes larger than the pressure (LS pressure) of the back pressure chamber 26 and the force (pressure conversion value) of the spring 25, and the function of the load check valve ( Backflow prevention function).

The pressure at the inlet port 14 rises and the back pressure chamber 2
6 becomes larger than the pressure (LS pressure) of the spring 6 and the force of the spring 25 (converted pressure value), the seat portion 23 is opened, and the pressure of the inlet port 14, the pressure of the back pressure chamber 26, and the force of the spring 25 are balanced. The amount of movement of the spool 20 is controlled, and the aperture of the diaphragm 21 is adjusted. As a result, the pressure at the inlet port 14 is controlled to be slightly higher than the LS pressure by an amount corresponding to the force of the spring 25, and as a result, the pressure at the inlet port 14 is changed to the inlet port of the pressure compensating valve related to the other actuator 10a. (Near the maximum load pressure).
Therefore, the pressure difference between the front and rear of the meter-in throttle 4 is kept substantially at the set pressure, so that a flow rate proportional to the opening of the throttle 4 is supplied to the actuator 10. Further, since the pressure at the inlet port of each pressure compensating valve is controlled to a pressure near the same maximum load pressure regardless of the magnitude of the load pressure, each actuator is operated at a shunt ratio corresponding to the opening area of the meter-in throttle 4. be able to.

As described above, according to the present embodiment, the pressure compensating valve 7 ensures the flow dividing characteristic during the combined operation, and the movable piston 40 selects the maximum pressure of the inlet pressure of each pressure compensating valve 7. And the movable sleeve 30 functions as a pressure selection valve that causes the pressure compensating valve 7 to perform the function of a load check valve (backflow prevention function), so that it is not necessary to separately provide a load check valve. Further, since the movable piston 40 is provided at the center of the compensating valve spool 20 and the movable sleeve 30 is provided at the outer peripheral portion of the compensating valve spool 20, the component compensating the pressure compensating valve 7 and the two kinds of pressure selecting valve functions can be made compact. In summary, the pressure compensating valve portion does not increase in size, and the hydraulic control valve can be downsized.

The movable sleeve 30 and the movable piston 4
0 is arranged separately at the center and outer periphery of the compensating valve spool, so that their functions are independent without affecting each other, and the individual operating conditions can be freely changed according to the specifications. Flexibility can be secured.

[0044]

According to the present invention, the movable piston is inserted into the compensating valve spool, and the movable sleeve is provided on the outer peripheral portion of the compensating valve spool, so that each of them can function as a pressure selection valve. There is no need to separately provide a check valve, and the components that fulfill the functions of the pressure compensating valve and the two types of pressure selection valves are compactly arranged. The pressure compensating valve is not enlarged, and the hydraulic control valve can be downsized.

Further, since the movable sleeve and the movable piston are arranged separately at the center and the outer periphery of the compensation valve spool,
These functions are independent, and the individual operating conditions can be freely changed according to the specifications, and the degree of freedom of design can be secured.

[Brief description of the drawings]

FIG. 1 is a structural diagram of one actuator of a hydraulic control valve according to an embodiment of the present invention.

FIG. 2 is a detailed structural view of a pressure compensating valve portion of the hydraulic control valve shown in FIG.

FIG. 3 is a diagram illustrating an example of a hydraulic circuit of a conventional load sensing system.

FIG. 4 is a diagram showing an example of a hydraulic circuit of a conventional load sensing system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hydraulic pump 2 Pump adjustment valve 3 Pilot valve 4 Meter-in restrictor 5 Tank 6 LS restrictor 7 Pressure compensation valve 8 Pressure selection valve 9 Pressure selection valve 10 Actuator 10A Actuator port 11 Load check valve 12 Pump port line 13a, 13b LS passage 14 Compensation Valve inlet port 15 Compensation valve outlet port 16 Meter-out restrictor 17 Spool 20 Compensation valve spool 22 Front sliding part 21 Restrictor 23 Seat part 24 Small room in spool 25 Spring 26 Back pressure chamber 27 Axial hole 30 Movable sleeve 32 Groove 33 Communication Hole 40 Piston 41 Hole 42 Small hole 43 Spring 50 Flange 51 Stopper 52 Flange convexity 53 Sliding surface 54 LS pressure chamber 55 LS pressure chamber 56 Body septum 60 Body

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kinya Takahashi 650, Kunitachi-cho, Tsuchiura-shi, Ibaraki Prefecture Within Hitachi Construction Machinery Engineering Co., Ltd.

Claims (1)

[Claims] 1. A composite device comprising a meter-in throttle for controlling a flow rate of pressure oil supplied to an actuator, and a pressure compensating valve disposed between an outlet side of the meter-in throttle and the actuator, and driving a plurality of actuators. During operation,
LS obtained by obtaining the outlet side pressure of the meter-in throttle from each of the pressure compensating valves from the highest pressure among the inlet pressures of the pressure compensating valves.
(A) the pressure compensating valve has a spool, and one end of the spool faces a compensating valve inlet port connected to an outlet side of the meter-in throttle; The other end faces the back pressure chamber, and a seat portion and a throttle portion are provided on the spool portion on the one end side with the direction of the compensation valve inlet port being closed, and a movable piston is provided in an axial through hole of the spool. Is slidably inserted,
A movable sleeve is slidably fitted on the outer peripheral portion on the other end side of the spool. (B) One end of the movable piston faces the compensation valve inlet port, and the other end is an LS to which the LS pressure is led. Facing the pressure chamber,
The movable piston is provided with a passage that allows communication between the compensation valve inlet port and the LS pressure chamber when the movable piston moves toward the LS pressure chamber, and a spring that biases the movable piston toward the compensation valve inlet port is provided, (C) one end of the movable sleeve faces the compensation valve outlet port, the other end faces the LS pressure chamber, and either of the compensation valve outlet port or the LS pressure chamber becomes high pressure in the movable sleeve. A hydraulic control valve, characterized in that a passage is provided for communicating the high pressure side to the back pressure chamber when the movable sleeve moves to the low pressure side.