JPH05332308A - Pressure oil supply device - Google Patents

Abstract

PURPOSE:To improve the statically determining ability of an actuator port by forming a communicating hole between the first load pressure detecting port and the first actuator port and the second load pressure detecting port in an opening to communicate with the second load pressure detecting port, and providing the communicating hole with a load check valve. CONSTITUTION:A communicating hole 123 between an actuator port 34 and a load pressure detecting port 45 is provided with a load check valve 124. Within a certain stroke range from the neutral position of a main spool 49, a pressure oil which flows into the first load pressure detecting port 45 and is discharged from a hydraulic pump 20 is checked in flowing out toward the actuator port 34 by the load check valve 124 until its pressure rises to the load pressure of an actuator 88. The pressure oil partially flows out from an opening 129 to a tank port 48 through an actuator port 35, and its flow out rate is proportional to the load pressure of the actuator 88. Since the early movement of the actuator 88 is slow in response with a load, and damping action is enlarged by the flow rate of the pressure oil flowing out to the tank port 48, the statically determining ability of the actuator 88 can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure oil supply device for supplying pressure oil discharged from one or a plurality of hydraulic pumps to a plurality of actuators.

[0002]

2. Description of the Related Art A pressure oil supply device disclosed in Japanese Patent Laid-Open No. 60-11706 is known. That is, as shown in FIG. 1, a plurality of pressure compensating valves 3, 1 are provided in the discharge conduit 2 of the hydraulic pump 1.
3 are connected in parallel, and directional control valves 5 and 15 are provided on the outlet conduits 4 and 14 of the pressure compensating valves 3 and 13, respectively, and the output sides of the directional control valves 5 and 15 are connected to actuators 6 and 16, respectively. A pressure oil supply device having a structure in which the pressure compensating valves 3 and 13 are pushed in the opening direction by the pump discharge pressure and the directional control valve outlet pressure, and pushed in the closing direction by the directional control valve inlet pressure and the highest load pressure. .. With this pressure oil supply device, the pump discharge pressure oil can be supplied to each actuator at a predetermined distribution ratio when a plurality of directional control valves 3 and 13 are simultaneously operated.

In such a pressure oil supply device, the shuttle valve 7 is indispensable for comparing the load pressure of the actuator and supplying the higher load pressure to the pressure compensating valve. Only one less than the number is needed, and the cost is higher. Further, in the above-described pressure oil supply device shown in FIG. 1, it is assumed that the two actuators 6 and 12 are both actuated, and the load pressure on the actuator 6 side is large among those load pressures. At this time, the pressure in the conduit 8 is guided to the conduit 9 by the shuttle valve 7 as the maximum load pressure. Next, it is assumed that the load pressure fluctuates and the load pressure on the actuator 16 side becomes larger than the load pressure on the actuator 6 side. At that time, that is, when the shuttle valve 7 is switched, the pressure in the conduit 18 is eliminated by the blow-through in the shuttle valve 7, and the pressure in the other conduit 8 is pushed in. Therefore, when the shuttle valve 7 is switched, the actuator 6 transiently descends naturally and the actuator 6 is accelerated. Therefore, the present applicant previously applied for a pressure oil supply device capable of solving the above-mentioned problems.

As shown in FIG. 2, such a pressure oil supply device is
A plurality of directional control valves 22 are provided in the discharge passage 21 of the hydraulic pump 20, and the check valve unit 2 is provided on the inlet side of each directional control valve 22.
3 and a pressure reducing valve portion 24 are provided respectively, and the directional control valve 22 and the pressure compensating valve 25 are provided.
Is configured as shown in FIG.

That is, as shown in FIG. 3, the valve block 30 has a substantially rectangular parallelepiped shape, and a spool hole 31 is formed in the left and right side surfaces 32 and 33 near the upper portion of the valve block 30, and the spool 31 is opened. The first and second actuator ports 34 and 35 are formed to open on the upper surface 36, and a check valve hole 37 opened to the left side surface 32 and a depressurization opening to the right side surface 33 are formed near the lower part of the valve block 30. The valve hole 38 is formed concentrically, the first port 39 opened to the check valve hole 37 is opened to the front and rear surfaces, and the second and third ports 42 opened to the pressure reducing valve hole 38. , 43 are formed with openings in the front and rear surfaces, and when the front and rear surfaces of the plurality of valve blocks 30 are butted and connected to each other,
The second and third ports 39, 42, 43 communicate with each other.

The valve block 30 has a pump port 44 opened in the spool hole 31, first and second load pressure detection ports 45 and 46, and first and second actuator ports 3
4, 35, first and second tank ports 47, 48 are formed, and first and second small diameter portions 50, 51 and a communication groove 52 are formed in the main spool 49 fitted in the spool hole 31. Yes, the main spool 49 has a first oil passage 53 that constantly connects the first and second load pressure detection ports 45 and 46, and a second oil that connects and disconnects the second load pressure detection port 46 and the second tank port 48. A passage 54 is formed, the spool 49 blocks each port with a spring, and the second oil passage 54 holds the spool 49 in a neutral position where the second load pressure detection port 46 and the second tank port 48 communicate with each other. Sliding on the second small diameter portion 51 communicates the second actuator port 35 with the second tank port 48, the communication groove 52 allows the pump port 44 to communicate with the second load pressure detection port 46, and the first small diameter portion 50. With the first actuator Over door 34 is the first load pressure detection port 4
5 and the first pressure oil supply position where the second load pressure detection port 46 and the second tank port 48 are shut off and the spool 49 is slid to the left, the first small diameter portion 50 causes the first actuator port 34 to move. To the first tank port 47, the communication groove 52 connects the pump port 44 to the first load pressure detection port 45, and the second small diameter portion 51 connects the second actuator port 35 to the second load pressure detection port 46. Communication,
And the second load pressure detection port 46 and the second tank port 48
The directional control valve 22 is constituted by the second pressure oil supply position where the valve is shut off.

The check valve hole 37 is opened to the pump port 44 through the oil passage 56, and the check valve hole 37 is fitted with a valve 60 for shutting off the communication between the first port 39 and the pump port 44. The valve 60 is restricted by a stopper rod 62 provided on the plug 61 so as not to slide leftward from the position shown in the figure, and is held at the shutoff position to form the check valve portion 23. The pressure reducing valve hole 38 is provided with the fourth port 57 and the oil passage 5.
8 communicates with the second load pressure detection port 46, the spool 64 is fitted into the pressure reducing valve hole 38 to form a first pressure chamber 65 and a second pressure chamber 66, and the first pressure chamber 65 is the first pressure chamber 65. The second pressure chamber 66 communicates with the third port 43, and the spring 69 is provided between the free piston 68 inserted into the blind hole 67 of the spool 64 and the bottom portion of the blind hole 67. The piston 68 abuts on the plug 70, and the push rod 71 integrally provided on the spool 64 projects from the through hole 72 to abut the valve 60 on the stopper rod 62. The spool 64 has a second port 42. The pressure reducing valve portion 24 and the check valve portion 23 form a pressure compensating valve 25 by forming a fine hole 73 communicating with the blind hole 67.

Then, as shown in FIG. 2, the hydraulic pump 20
The discharge path 21 of the first port 39 and the second port 42 are communicated with each other, and the load pressure detection path 82 is connected to the third port 43.
-The actuator 88 is connected to the second actuator ports 34 and 35. In FIG. 2, 83 is a swash plate that controls the discharge flow rate of the hydraulic pump 80, 84 is a servo cylinder, and 85 is a directional control valve for pump adjustment.

Next, the operation will be described with reference to FIG. When the directional control valve 22 is in the neutral position A. Hydraulic pump 20
The oil sucked up from the tank 86 by the discharge passage 21
And is guided to the pressure chamber a in the opening direction of the check valve portion 23. At this time, the pressure chambers 65 and 66 of the pressure reducing valve unit 24 are
Since both communicate with the tank 86, the pressure chamber 65,
The pressures of both 66 are zero, so that the pressure reducing valve portion 24 is pushed by the weak spring 69 and the rod 71 is pushed.
It just abuts. On the other hand, the pump discharge pressure is kept constant by the spring 87 of the pump adjusting directional control valve 85, which is a differential pressure from the pressure of the load pressure detection path 82. Now
If this differential pressure is 20 kg / cm ² , the load pressure detection path 82
Since the pressure in the pump is zero, the pump discharge pressure is 20 kg / cm ²
And at the same time, the pump discharge pressure flows into the pressure chamber a of the check valve section 23, and strokes until the inlet pressure of the directional control valve 22 (the outlet pressure of the check valve section 63) becomes equal to the pump discharge pressure. For example, the receipt is made by the weak spring 69. The pressure reducing valve section 24 is
While the pump discharge passage 81 and the pressure chamber 66 are communicated with each other, the check valve portion 23 communicates the pump discharge passage 81 and the outlet side before reaching the stroke end.
When 2 is in the neutral position A, the pump discharge passage 21 and the pressure chamber 6
6 does not communicate with each other, and the pressure in the pressure chamber 65 remains zero.

Only one of the directional control valves 22 is first
When making a stroke to the pressure oil supply position B. Now, the left directional control valve 22 is stroked to the first pressure oil supply position B, and the right directional control valve 22 is set to the neutral position A. The directional control valve 22 is stroked to connect the pump port 44 and the first actuator port 34, and at the same time, connect the second actuator 35 and the second tank port 48.
At this time, when the pressure (load pressure) in the conduit 89 connecting the first actuator port 34 and the actuator 88 is higher than the pump discharge pressure (20 kg / cm ² ), the check valve portion 23 receives the pressure in the pressure chamber b. It is possible to prevent the actuator 88 from naturally descending. The pressure of the conduit 89 of the actuator 88, that is, the load pressure is the first
One of the pressure chambers 6 of the pressure reducing valve section 24 from the oil passage 53 and the passage 58.
Guided to 5. Since the pressure in the other pressure chamber 66 is zero, the pressure reducing valve unit 24 strokes in the direction of disengagement from the check valve unit 23 to the stroke end, and the pressure reducing valve unit 24
Pump discharge passage 21 and load pressure detection passage 82
Communicate with each other. When the pressure (load pressure) inside the conduit 89 is higher than the pump discharge pressure (= 20 kg / cm ² ), the pressure is closed by the pressure in the pressure chamber b of the check valve portion 23, and the pressure is reduced by one of the pressure reducing valve portions 24. Since it is guided to the pressure chamber 65, even if the other pressure chamber 66 and the pump discharge passage 21 communicate with each other, the pressure reducing valve portion 24 remains stroked. On the other hand, the pressure (load pressure) in the conduit 41 is the pump discharge pressure (= 20 kg / cm ² ).
When the pressure is smaller, the load pressure is guided to one pressure chamber 65 of the pressure reducing valve portion 24, and the pressure reducing valve portion 24 has one pressure chamber 65.
Although the stroke is caused by the pressure of, the pressure of the other pressure chamber 66 rises to the pressure of the one pressure chamber 65 (that is, the load pressure), and the weak spring 69 makes contact with the check valve portion 23. In any case, the pressure reducing valve section 24 connects the pump discharge passage 21 and the pressure chamber 66 until the pressure in the one pressure chamber 65 and the pressure in the other pressure chamber 66 become equal to each other,
If the pressures in both pressure chambers 65 and 66 become equal, the weak spring 6
9 and abuts against the check valve portion 23. As a result, the pressure in the load pressure detection path 82 becomes equal to the load pressure,
The pump discharge pressure is controlled by the pump adjusting directional control valve 85 to a pressure higher than the pressure in the load pressure detection passage 82 by a certain differential pressure (here, 20 kg / cm ² ). This pump discharge pressure is guided to the pump port 44 via the check valve portion 23, that is, between the inlet pressure and the outlet pressure (= load pressure) of the directional control valve 22.
20 kg / cm ² ) will be maintained. Therefore, the flow rate supplied to the actuator 88 is controlled only by the change in the opening area of the throttle between the inlet side and the outlet side due to the stroke of the directional control valve 22. When the directional control valve 22 is stroked, the conduit 89 or 90 of the actuator 88 and the second oil passage 53 for introducing load pressure are connected,
On the other hand, the second oil passage 53 is connected to one pressure chamber 6 of the pressure reducing valve portion 24.
5, the load pressure in the pressure reducing valve portion 24 is used only as pilot pressure (set pressure of the pressure reducing valve portion), so the pressure is not lost, that is, the directional control valve 22 is stroked. In this case, the actuator 88 does not naturally descend due to the load pressure being removed.

The load pressure detecting path 82 is provided with the pressure reducing valve section 2 of the pressure compensating valve 25 disposed in the other directional control valve 22.
4 is also connected to the other pressure chamber 66, but one pressure chamber 65 of the pressure reducing valve portion 24 is connected to the tank 86 by the neutral position A of the directional control valve 22, and therefore is used for introducing load pressure. The pressure in the first oil passage 53 is zero, so that the pressure chamber 66
The pressure reducing valve portion 24 urges the pressure reducing valve portion 24 in a direction to close the check valve portion 23. On the other hand, since the pump discharge pressure is introduced from the pump discharge path 81 to the pressure chamber a in the direction of opening the check valve portion 24, the difference between the pump discharge pressure and the pressure in the load pressure detection path 82 (= 20 kg / cm ² ), the check valve portion 23 and the pressure reducing valve portion 24 are stroked in the opening direction of the check valve portion 23.
g / cm ² ), the weak spring 69 causes a receipt, and as a result, the pressure reducing valve section 24 does not stroke to the stroke end, and there is no effect on the hydraulic control of the directional control valve 22 side. ..

When any of the directional control valves 22 is stroked to the first pressure oil supply position B. -When the total flow rate required for each actuator 88 is at the maximum discharge flow rate position of the hydraulic pump 20. Now, it is assumed that the directional control valve 22 is both stroked to the first pressure oil supply position B, and the pump ports 44, the conduits 89, and the first oil passages 53 for introducing the load pressure are connected to each other. In the pressure reducing valve portion 24, the pressure in the pressure chamber 66 is one pressure chamber 65.
Until it becomes equal to the internal pressure, and the other pressure reducing valve section 24
Respectively continue to stroke to the stroke end until the pressure in the pressure chamber 66 becomes equal to the pressure in one pressure chamber 65. Now two actuators 8
It is assumed that the load pressure of the left actuator 88 is larger than the load pressure of 8,88. It is assumed that the load pressure of the left actuator 26 is 100 (kg / cm ² ) and the load pressure of the right actuator 27 is 10 (kg / cm ² ).
Since the load pressure detection path 82 is connected to the tank 86 via the throttle 91, the pressure in the load pressure detection path 82 is zero before the stroke of the directional control valve. Therefore, each pressure reducing valve unit 2
4 also makes a stroke by the pressure in the first oil passage 53 for load pressure detection, so that the pump discharge pressure communicates with the pressure in the pressure detection conduit 34. The pressure in the conduit 90 of the actuator 88 on the right side where the pressure in the load pressure detection path 82 is the low pressure side (10
When the pressure is increased to (kg / cm ² ), first, the pressure reducing valve portion 24 of the pressure compensating valve 25 on the right side is closed. Left pressure compensation valve 25
The pressure reducing valve section 24 of the No. 2 is still stroked, and the pressure in the load pressure detecting path 82 is the pump discharge pressure (20 kg / cm ² ).
Rises up to. At this time, the pressure of the pump port 44 of the directional control valve 55 of the left side actuator 88 on the high pressure side is 100 (kg / cm ² ), the check valve portion 23 of the pressure compensation valve 25 is closed, and the pressure reducing valve portion 24 is closed.
Is dissociated from. On the other hand, the pressure reducing valve section 24 of the pressure compensating valve 25
Is the pressure difference between the two pressure chambers 65 and 66 (20-10
= 10 kg / cm ² ), the check valve portion 23 is urged in the closing direction. On the other hand, the pressure in the pressure chamber a in the opening direction of the check valve portion 23 (pump discharge pressure) is 20 (kg / cm ² ).
Therefore, as a result, the check valve portion 23 is opened until the pressure of the pump port 44 of the directional control valve 22 becomes 10 (kg / cm ² ), and then the receipt is made by the weak spring 69. By a pump adjusting direction control valve 85, there differential pressure (20kg / cm ²⁾ amount corresponding, pump discharge pressure from the high pressure pressure (20kg / cm ²⁾ of the load pressure Detchi 82 is controlled (40 kg / cm ² ). Also at this time, the pressure in the load pressure detection path 82 becomes 40 (kg / cm ² ) with the check valve portion 23 of the pressure compensation valve 25 on the high pressure side kept closed and the pressure reducing valve portion 24 still on the stroke, while the low pressure side The pressure reducing valve portion 24 of the pressure compensating valve 25 of No. 2 has a pressure difference (= 30 kg / c) between the load pressure detection path 82 and the first oil path 53 for introducing load pressure.
m ² ), the check valve portion 23 is biased in the closing direction, and as a result, the pressure of the pump port 44 of the directional control valve 22 becomes 10
It remains kg / cm ² . In this way, the pressure in the load pressure detection path 82 and the pump discharge pressure continue to rise, and when the pump discharge pressure eventually becomes equal to the load pressure (100 kg / cm ² ) of the high-pressure side actuator 88, the high-pressure side pressure compensation is performed. The pressures in the two pressure chambers 65 and 66 of the pressure reducing valve portion 23 of the valve 25 are both 100 kg / cm ² , and the weak spring 6
9, the closing check valve portion 23 is abutted. At this time, the pressure reducing valve portion 24 of the pressure compensating valve 25 on the low pressure side has the pressure difference (10) between the load pressure detecting passage 82 and the first oil passage 53 for introducing the load pressure.
0-10 = 90 kg / cm ² ), the check valve portion 23 is biased in the closing direction, and as a result, the low-pressure side directional control valve 22
The pump port 44 pressure remains at 10 kg / cm ² . Again, the pump adjusting directional control valve 85 controls the pump discharge pressure to 120 (kg / cm ² ). At this time, the pressure reducing valve portion 23 of the pressure compensating valve 25 on the high pressure side is only in contact with the check valve portion 23 by the weak spring 69, and due to the pressure difference between the two pressure chambers a and b of the check valve portion 23, For the first time, the check valve portion 23 opens and the pump discharge pressure (120 kg / cm ² ) is introduced to the pump port 44 of the directional control valve 22. On the other hand, the pressure reducing valve portion 24 of the pressure compensating valve 25 on the low pressure side closes the check valve portion 23 by the pressure difference (= 90 kg / cm ² ) in the load pressure detecting passage 82 and the first oil passage 53 for introducing the load pressure. However, the pressure in the pressure chamber a in the opening direction of the check valve portion 23 is 120
(Kg / cm ² ), the pressure of the inlet port 44 of the directional control valve 22 is 30 (kg / cm ² ) (120-9
0), the check valve portion 23 and the pressure reducing valve portion 24
Balances pressure. That is, the check valve portion 23 and the pressure reducing valve portion 24 make a slight stroke, and the check valve portion 2
3 to 120 kg / cm ² to 30 kg / cm ²
It will be in a state where it is squeezed to become. For the first time, this hydraulic control system is balanced so that the pressure at the pump port 44 of the directional control valve 22 on the high pressure side is 120 kg / cm ² , and the pressure at the pump port 44 of the directional control valve 22 on the low pressure side is 30 kg / cm ² .
cm ² , that is, the two directional control valves 22, 22
The difference between the inlet pressure and the outlet pressure (load pressure) is 20 kg /
By being kept at cm ² , the two directional control valves 22,
22 is the actuator 8
It becomes possible to control the flow rate supplied to 8,88.

The total flow rate required for each actuator 88, 88 is greater than or equal to the maximum discharge flow rate of the hydraulic pump 80. Now, the load pressure and required flow rate of the actuators 88, 88 are set to 100 kg for the actuator 88 on the left side.
/ Cm ² , 501 / min, right actuator 88
Is 10 kg / cm ² and 501 / min. When the maximum discharge flow rate of the hydraulic pump 80 is 1001 / min or more, as described above, the difference between the inlet pressure and the outlet pressure of the directional control valves 22, 22 is kept constant (= 20 kg / cm ² ),
The flow rate can be controlled by the stroke, and the flow rate can be distributed by 501 / min. Next, assume that the stay discharge amount of the hydraulic pump 80 becomes 701 / min. The inlet pressure of the two directional control valves 22, 22 is 120 kg /
Since it is cm ² and 30 kg / cm ² , the flow rate to the directional control valve 22 on the high pressure side is 501 / min to 201 / min.
Decrease to. The flow rate to the directional control valve 22 on the low pressure side is 501 /
It remains at min. If the strokes (opening areas) of the two directional control valves 22 and 22 are not changed, the differential pressure between the inlet pressure and the outlet pressure of the directional control valve 22 on the high pressure side is reduced from 20 kg / cm ² by the amount of the reduced flow rate. Now the differential pressure is 14k
g / cm ² , that is, the inlet pressure is 120 kg / cm ^2.
To 114 (100 + 14) kg / cm ² . At this time, the pressures of the two pressure chambers 65 and 66 of the pressure reducing valve portion 24 of the pressure compensating valve 25 both remain at 100 kg / cm ² , so the pressure reducing valve portion 24 abuts against the check valve portion 23 by the weak spring 69. The pressure inside the pressure chamber b in the closing direction of the check valve portion 23 is 120 kg.
/ Cm ² to 114 kg / cm ² , the pressure in the pressure chamber a in the opening direction of the check valve portion 23, that is, the pump discharge pressure is 120 kg /, while the check valve portion 23 remains open (stroke end). cm ² to 114 kg
Reduced to / cm ^2. At this time (when pump discharge flow rate is insufficient)
Therefore, the pump discharge pressure does not depend on the control of the pump adjusting directional control valve 85. On the other hand, the two pressure chambers 65 and 66 of the pressure reducing valve portion 24 of the pressure compensating valve 25 on the low pressure side are 100 kg / c.
m ² , 10 kg / cm ² , the differential pressure is 90 kg /
Continue to urge the check valve portion 63 to close in cm ² . On the other hand, since the pressure in the pressure chamber a in the opening direction of the check valve portion 23, that is, the pump discharge pressure is reduced to 114 kg / cm ² , the pressure chamber b in the closing direction of the check valve portion 23 is reduced.
When the internal pressure is reduced from 30 kg / cm ² to 24 kg / cm ² , the check valve portion 23 and the pressure reducing valve portion 24 balance the pressure. Therefore, the differential pressure between the inlet pressure and the outlet pressure of the directional control valve 22 on the low pressure side is 20 kg / cm ² to 14 kg / c.
m ² (24-10). Due to the decrease in the differential pressure of the directional control valve 22, the supply flow rate to the low-pressure side actuator 88 decreases from 501 / min, and the supply flow rate to the high-pressure side actuator 88 increases from 201 / min. That is, the differential pressure between the inlet pressure and the outlet pressure of the directional control valves 22 and 22 is equal, and the two actuators 8 are
This hydraulic control system is balanced in a state where the supply amounts to 8 and 88 are both divided into 351 / min.

When the number of actuators loaded by one hydraulic pump 80 is three or more. Even when there are three or more actuators, the pressure compensating valve 25 having the same check valve portion 23 and pressure reducing valve portion 24 is disposed between the directional control valve and the hydraulic pump, and the pressure in the closing direction of each pressure reducing valve portion is arranged. Even if the number of actuators is three or more, the operation according to the above-described operation principle can be realized only by communicating all the differences by the load pressure detection path 82.

[0015]

With such a pressure oil supply device, the stroke of the main spool 49, that is, the first stroke, does not depend on the magnitude of the load even at the fine control position where the main spool 49 of the directional control valve 22 is slightly stroked. The flow rate proportional to the opening area of the second actuators 34, 35 and the first and second load pressure detection ports 47, 48 is supplied to the actuator 88, and the acceleration of the actuator 88 that starts to move becomes rapid. The actuator 88 will suddenly start moving. Further, when the main spool 49 of the directional control valve 22 is stopped at a position midway from the neutral position to the pressure oil supply position, even if the load on the actuator 88 is large, a flow rate proportional to the opening area can be obtained.
Since it is supplied to the actuator 8, the static determinability of the actuator 88 is deteriorated.

Therefore, an object of the present invention is to provide a pressure oil supply device capable of solving the above-mentioned problems.

[0017]

A communication hole for connecting a first load pressure detection port 45 and a first actuator port 34 to a main spool 49 within a range in which the main spool 49 is slid from a neutral position by a stroke. 123 and the second load pressure detection port 46 are formed with an opening 129 for communicating with the second load pressure detection port 35, and pressure oil from the first actuator port 34 to the first load pressure detection port 45 is formed in the communication hole 123. A pressure oil supply device provided with a load check valve 124 for blocking the flow.

[0018]

[Operation] Within the range in which the main spool 49 is slid from the neutral position by a certain stroke, the pressure oil discharged from the hydraulic pump 20 that has flowed into the first load pressure detection port 45 is the actuator 88.
Until it reaches a pressure commensurate with the load pressure of the load check valve 124, it is prevented from flowing out to the first actuator port 34, and a part of the pressure oil passes through the second actuator port 35 from the opening 129 to reach the first actuator port 34. 2 tank port 4
8 and the amount of the outflow is proportional to the load of the actuator 88. Therefore, the start of movement of the actuator becomes slower according to the load, and the damping due to the flow rate flowing out to the tank port becomes large, so that the actuator becomes quiet. Qualitativeness is improved.

[0019]

EXAMPLE An example of the present invention will be described with reference to FIG. It should be noted that the same members as those in the conventional art have the same reference numerals. On the left side of the main spool 49, a communication hole 123, which is composed of a radial first hole 120, a shaft hole 121, and a radial second hole 122 and which connects and disconnects the first actuator port 34 and the first load pressure detection port 45. The communication hole 123 is provided with a load check valve 124 for preventing pressure oil from flowing from the first actuator port 34 to the first load pressure detection port 45. This load check valve 124 is provided with a valve 126 in a blind hole 125 formed in the axial center of the main spool 49.
A spring 128 is provided between the valve 26 and the plug 127.
6 is pressed against the shaft hole 121. On the right side of the main spool 49, there is formed a slit-shaped opening 129 for connecting / disconnecting the second load pressure detection port 46 and the second actuator port 35. 130 is the first and second load pressure detection port 4
It is a communication passage that always connects 5, 46.

Next, the operation will be described. When the main spool 49 is in the neutral position, the first load pressure detection port 45 and the first actuator port 34 are not communicated with each other through the communication hole 123, and the second load pressure detection port 46 and the second actuator port 35 are opened at the opening 129. Does not communicate. Main spool 49
A stroke from the neutral position (70
%) Within the range slid to the right, the pump port 44 is located at the intermediate small-diameter portion 131 of the main spool 49 and the notch 132 on the right side.
Opens to the second load pressure detection port 46. At approximately the same timing as this, the first hole 120 is connected to the first load pressure detection port 4
Open to 5. As a result, the pressure oil discharged from the hydraulic pump 20 is transferred to the first port 39, the pump port 44, and the intermediate small diameter portion 13.
1, right side notch 132, second load pressure detection port 46,
Communication passage 130, first load pressure detection port 47, first hole 12
At 0, it flows in just before the load check valve 124. If the actuator 88 is, for example, an arm cylinder of a power shovel, the holding pressure acts on the first actuator port 34, but the load check valve 124 prevents the holding pressure from flowing to the first load pressure detection port 45.

As a result, the pressure oil discharged from the hydraulic pump 20 becomes a dead end.
The discharge pressure of 0 rises, and the discharge pressure is
When the holding pressure acting on 24 is raised, the load check valve 124 opens, and the discharge pressure oil of the hydraulic pump 20 is supplied to the actuator 88 from the first actuator port 34 through the second hole 122 by the load check valve 124. .. On the other hand, in the range where the main spool 49 slides by the right stroke as described above, the second load pressure detection port 46 opens to the second actuator port 35 at the opening 129 and at the same time the second load pressure detection port opens. 46 opens to the second tank port 48 at the second small diameter portion 51 and the notch 133. As a result, a part of the pressure oil discharged from the hydraulic pump 20 will flow out to the second tank port 48, and the flow rate of the outflow will be the load pressure acting on the first actuator port 34 (holding pressure of the actuator 88). The load (holding pressure) of the actuator 88 increases as it increases in proportion to the size of
When the load is large, the flow rate flowing out to the second tank port 48 increases, and when the load is small, the second tank port 4
Since the flow rate outflowing to 8 decreases, the acceleration at the beginning of movement of the actuator 88 becomes gentle according to the load, and the feeling of popping out disappears, and the flowout to the second tank port 48 causes a large attenuation, resulting in a large attenuation of the actuator. Qualitativeness is improved. Since the opening area of the striation-shaped opening 129 is much smaller than that of the cutout 132 and the first hole 120 on the right side, the speed of the actuator 88 does not become too slow due to the flow rate flowing out to the second tank port 48.

When the main spool 49 is slid rightward over a certain stroke (for example, over 70% of the total stroke), the second load pressure detection port 46 and the second actuator port 35 are communicated with each other through the opening 129 having a striation shape. The pressure oil discharged from the hydraulic pump 20 disappears from the first spool 49 of the main spool 49.
The small-diameter portion 50 supplies the first load pressure detection port 45 and the first actuator port 34 by an amount proportional to the opening area of the first actuator pressure port 34, and the speed of the actuator 88 increases. At this time, since the actuator 88 has already begun to move, even if a part of the pressure oil discharged from the hydraulic pump 20 does not flow out to the second tank port 48, there is no problem in the start of movement, and the absolute speed of the actuator 88 is to some extent. Since it is large, there is no problem with static stability, and the actuator 88
Since the discharge pressure of the hydraulic pump 20 is higher than the holding pressure of
From the actuator port 34 to the first load pressure detection port 4
5 does not flow back, and there is no problem even if the first actuator port 34 and the first load pressure detection port 45 are communicated with each other through the first small diameter portion 50 as described above. The opening area of the eta port 34 and the first load pressure detection port 45 can be secured to a value commensurate with the sliding amount (stroke) of the main spool 49. The stroke when the communication hole 123 ends the communication and the stroke when the communication hole 123 ends the communication may be the same or different.

In the above embodiment, the load check valve 124
Although the communication hole 123 provided with is formed on the left side of the main spool 49, it may be provided on both the left and right sides of the main spool 49. In this way, the actuator 88 can be used as a turning motor for a power shovel. 2 actuator port 3
It is possible to deal with the case where the holding pressure acts on 4, 35. ．

Referring to FIG. 4, the spool 64 is used to block the third port 43 and the second pressure chamber 66 of the pressure reducing valve section 24, and the spool 100 is provided with a strip-shaped opening 100 for connecting and blocking the third port 43 and the second port 42. 64 and the second port 4
The second pressure oil is directly supplied from the third port 43 to the load pressure detection path 82. The second pressure chamber 66 communicates with the third port 43 via the damper throttle 101, and the pressure chamber 102 of the free piston 68 communicates with the opening 100 with the damper throttle 103. As a result, when the spool 64 slides to the right, the pressure oil in the second pressure chamber 60 flows through the damper throttle 101 to the third port 43, and the pressure oil in the pressure chamber 102 passes through the damper throttle 103. Since the spool 64 flows to the second port 42, the spool 64 can be prevented from abruptly sliding to the right, and when the spool 64 slides to the left, pressure oil flows contrary to the above, so that it suddenly slides to the left. It can be prevented from moving.

Regarding the check valve portion 23, a small diameter portion 104 for communicating / blocking the first port 39 and the pump port 44 is formed in the spool 60 of the check valve portion 23, and the pressure chamber 105 for pushing the spool 60 to the right is formed in the first portion. It is partitioned from the first port 39, and communicates with the first port 39 through a communication hole 108 and a damper aperture 106 formed on the spool 60. As a result, when the spool 66 slides to the right and left, the first port 39
Since the pressure oil flows between the pressure chamber 105 and the pressure chamber 105 through the damper throttle 106, it is possible to prevent the spool 66 from abruptly sliding leftward and rightward.

[0026]

The hydraulic pump 20 is provided within a range in which the main spool 49 slides a stroke from the neutral position due to the communication hole 123 provided with the load check valve 124 and the opening 129.
Part of the discharge amount flows out to the tank port until the discharge pressure matches the load pressure, and the outflow amount is proportional to the load, so when the main spool 49 is slid a short stroke, the actuator moves slowly. Then, even when the main spool 49 is stopped at that position, the damping is large and the static determinability of the actuator is improved. Also, the main spool 4
When 9 slides for more than the stroke, the flow rate proportional to the opening area of the first load pressure detection port 45 and the first actuator port 34 can be supplied to the actuator.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a conventional pressure oil supply device.

FIG. 2 is a circuit diagram of a pressure oil supply device previously applied.

FIG. 3 is a cross-sectional view showing a specific example of a pressure compensation valve and a direction control valve.

FIG. 4 is a sectional view showing an embodiment of the present invention.

[Explanation of symbols]

20 ... Hydraulic pump, 21 ... Discharge passage, 22 ... Direction control valve,
23 ... Check valve part, 24 ... Pressure reducing valve part, 25 ... Pressure compensation valve, 30 ... Valve block, 31 ... Spool hole, 34 ... First
Actuator port, 35 ... Second actuator port, 37 ... Check valve hole, 38 ... Pressure reducing valve hole, 39 ...
1st port, 42 ... 2nd port, 43 ... 3rd port, 4
4 ... Pump port, 45 ... First load pressure detection port, 46
… Second load pressure detection port, 47… First tank port, 4
8 ... Second tank port, 49 ... Main spool, 53 ... First
Oil passage, 54 ... Second oil passage, 56 ... Oil hole, 58 ... Oil hole, 60
... Spool, 64 ... Spool, 65 ... First pressure chamber, 66
... second pressure chamber, 69 ... spring, 82 ... load pressure detection path, 88
... Actuator, 123 ... communication hole, 124 load check valve, 129 ... opening.

Claims (1)

[Claims] 1. A spool hole 31, a check valve hole 37 and a pressure reducing valve hole 38 are formed in a valve block 30, and a pump port 4 opened in the spool hole 31 in the valve block 30.
4, first and second load pressure detection ports 45 and 46, first and second actuator ports 34 and 35, and first and second tank ports 47 and 48, respectively.
The main spool 49 that connects and disconnects each port is fitted into the directional control valve 22 to form a directional control valve 22, and the valve block 30 includes a first port 39 opened in the check valve hole 37 and a check valve hole 37. Forming an oil passage 56 communicating with the first valve 39 and the oil passage 56 in the check valve hole 37, and inserting the spool 60 that is stopped at the cutoff position into the check valve portion 23, The valve block 30 is provided with a second opening 38 for reducing the pressure reducing valve.
-The third port 42, 43 is formed, and the pressure reducing valve hole 38 is formed.
The first pressure chamber 65 and the second pressure chamber 66 are formed by inserting the spool 64 into the first pressure chamber 65, the first pressure chamber 65 is communicated with the second load pressure detection port 46, and the second pressure chamber 66 is connected to the third port 43. And the spool 64 of the check valve portion 23 is pressed and held in the shut-off position to form the pressure reducing valve portion 24, and the pressure reducing valve portion 24 and the check valve portion are connected to each other. 23 as a pressure compensation valve 25, and the first
-The discharge port 21 of the hydraulic pump 20 is attached to the second ports 39 and 42.
And a load pressure detection path 82 is connected to the third port 43, and the first spool is connected to the main spool 49 in a range in which the main spool 49 is slid by a stroke from the neutral position toward the pressure oil supply device. A communication hole 123 that communicates the actuator port 34 and the first load pressure detection port 45 and an opening 129 that communicates the second load pressure detection port 46 and the second actuator port 35 are formed, and in the main spool 49, A communication portion that communicates with the first actuator port 34 and the first load pressure detection port 45 with an opening area proportional to the stroke when sliding for a certain stroke or more is formed.
3 is a load check valve 1 that blocks the flow of pressure oil from the first actuator port 34 to the first load pressure detection port 45.
24 is a pressure oil supply device.