JP3119317B2 - Pressure oil supply device - Google Patents

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 discharge oil from one or more hydraulic pumps to a plurality of actuators, in particular, a left-right traveling hydraulic motor.

[0002]

2. Description of the Related Art A pressure oil supply device disclosed in Japanese Patent Application Laid-Open No. Sho 60-11706 is known. That is, as shown in FIG. 1, a plurality of pressure compensating valves 3 and 1 are connected to the discharge conduit 2 of the hydraulic pump 1.
3 are connected in parallel, and directional control valves 5 and 15 are provided at outlet pipes 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. The pressure oil supply device has a structure in which the pressure compensating valves 3 and 13 are pushed in the opening direction by the pump discharge pressure and the direction control valve outlet pressure, and are pushed in the closing direction by the direction 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 pressurized oil supply device, a shuttle valve 7 is required to supply a higher load pressure to the pressure compensating valve by comparing the load pressure of the actuator. One less than the number is needed, which increases the cost. Further, in the case of the pressure oil supply device shown in FIG. 1 described above, it is assumed that the two actuators 6 and 12 are operated together, and the load pressure on the actuator 6 side is larger than the load pressure. 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 released by the blowout in the shuttle valve 7 and the pressure in the other conduit 8 is suppressed. Therefore, when the shuttle valve 7 is switched, the actuator 6 transiently descends spontaneously and the actuator 6 is accelerated. Therefore, the present applicant has previously filed an application for a pressure oil supply device capable of solving the above-mentioned problem.

[0004] Such a pressure oil supply device is, as shown in FIG.
A plurality of directional control valves 22 are provided in a discharge path 21 of the hydraulic pump 20, and a check valve unit 2 is provided at an inlet side of each of the directional control valves 22.
3 and a pressure compensating valve 25 comprising a pressure reducing valve section 24. The directional control valve 22 and the pressure compensating valve 25
Are 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 near the upper portion of the valve block 30 so as to open on the left and right side surfaces 32 and 33. First and second actuator ports 34 and 35 are formed in the upper surface 36 so as to be opened. Near the lower portion of the valve block 30, a check valve hole 37 opened in the left side 32 and a decompression opening opened in the right side 33. A valve hole 38 is formed concentrically, a first port 39 opened in the check valve hole 37 is formed in the front and rear surfaces, and a second and third port 42 opened in the pressure reducing valve hole 38. , 43 are formed to be open at the front and rear surfaces.
The second and third ports 39, 42, 43 communicate with each other.

The valve block 30 has a pump port 44 opened to the spool hole 31, first and second load pressure detection ports 45 and 46, and the first and second actuator ports 3.
4 and 35, first and second tank ports 47 and 48 are formed, and first and second small diameter portions 50 and 51 and a communication groove 52 are formed in a main spool 49 inserted into the spool hole 31. The main spool 49 has a first oil passage 53 which always connects the first and second load pressure detection ports 45 and 46 and a second oil which connects and shuts off 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 is held at a neutral position where the second load pressure detection port 46 and the second tank port 48 communicate with each other by the second oil passage 54, and the spool 49 is moved rightward. , The second actuator port 35 communicates with the second tank port 48 at the second small diameter portion 51, the pump port 44 communicates with the second load pressure detection port 46 at the communication groove 52, and the first small diameter portion 50. And the first actuator Over door 34 is the first load pressure detection port 4
5 and the second load pressure detection port 46 and the second tank port 48 are shut off to the first pressure oil supply position. When the spool 49 is slid to the left, the first actuator port 34 is formed by the first small diameter portion 50. To the first tank port 47, the communication port 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
Is a second pressure oil supply position at which the directional control valve 22 is shut off.

The check valve hole 37 opens to the pump port 44 through an oil passage 56, and a valve 60 for shutting off the communication between the first port 39 and the pump port 44 is inserted into the check valve hole 37. The valve 60 is regulated by a stopper rod 62 provided on the plug 61 so as not to slide to the left from the illustrated position, and is held at the shut-off position to constitute the check valve portion 23. The pressure reducing valve hole 38 is provided between the fourth port 57 and the oil passage 5.
At 8, it communicates with the second load pressure detection port 46, and a spool 64 is inserted into the pressure reducing valve hole 38 to form a first pressure chamber 65 and a second pressure chamber 66. The second pressure chamber 66 communicates with the fourth port 57, the second pressure chamber 66 communicates with the third port 43, and a spring 69 is provided between the free piston 68 inserted into the blind hole 67 of the spool 64 and the bottom of the blind hole 67. The piston 68 contacts the plug 70, and the push rod 71 integrally provided on the spool 64 projects from the through hole 72 to contact the valve 60 with the stopper rod 62. The pressure reducing valve portion 24 is formed by forming a fine hole 73 communicating with the blind hole 67, and the pressure compensating valve 25 is formed by the pressure reducing valve portion 24 and the check valve portion 23.

[0008] Then, as shown in FIG.
Is connected to the first port 39 and the second port 42, 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 hydraulic pump.
A swash plate for controlling the discharge flow rate of the pump 20, a servo cylinder 84, and a pump adjusting direction control valve 85.

Next, the operation will be described with reference to FIG. When the direction control valve 22 is in the neutral position A. The oil sucked from the tank 86 by the hydraulic pump 20 is guided to the pressure chamber a in the opening direction of the check valve portion 23 through the discharge path 21. At this time, since the pressure chambers 65 and 66 of the pressure reducing valve section 24 both communicate with the tank 86, the pressure chambers 65 and 66
Are zero, so that the pressure reducing valve portion 24 is only pushed by the weak spring 69 and the rod 71 is in contact with the check valve portion 23. On the other hand, the pump discharge pressure is maintained at a constant pressure difference from the pressure in the load pressure detection path 82 by the spring 87 of the pump adjustment direction control valve 85. Now, assuming that the differential pressure is 20 kg / cm ² , the pressure in the load pressure detecting path 82 is zero, so the pump discharge pressure rises to 20 kg / cm ^2, and at the same time, the pump discharge pressure flows into the pressure chamber a of the check valve portion 23. Then, the stroke is performed until the inlet pressure of the directional control valve 22 (the outlet pressure of the check valve portion 63) becomes equal to the pump discharge pressure. Pressure reducing valve 24, when the stroke end only, Pong
While the discharge passage 21 communicates with the pressure chamber 66, the check valve section 23 stops the pump discharge before reaching the stroke end.
Since the outlet 21 communicates with the outlet side, when the direction control valve 22 is at the neutral position A, the pump discharge passage 21 does not communicate with the pressure chamber 66, and the pressure in the pressure chamber 65 remains zero.

Only one of the directional control valves 22 is the 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 direction control valve 22 is moved to connect the pump port 44 and the first actuator port 34, and at the same time, the second
The tutor port 35 and the second tank port 48 are connected. 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. , The natural descent of the actuator 88 can be prevented.
The pressure of the conduit 89 of the actuator 88, that is, the load pressure, is guided from the first oil passage 53 and the passage 58 to one pressure chamber 65 of the pressure reducing valve section 24. Since the pressure in the other pressure chamber 66 is zero, the pressure reducing valve portion 24 strokes to the stroke end in a direction in which the pressure reducing valve portion 24 is dissociated from the check valve portion 23, and communicates with the pump discharge passage 21 through the throttle of the pressure reducing valve portion 24. The pressure detection path 82 communicates. When the pressure (load pressure) in 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 section 23, and the pressure is reduced to one of the pressure reducing valve sections 24. Since the pressure chamber 65 is guided to the pressure chamber 65, even if the other pressure chamber 66 and the pump discharge path 21 communicate with each other, the pressure reducing valve section 24 remains in a stroke. on the other hand,
The pressure (load pressure) in the conduit 89 is the pump discharge pressure (= 20k)
g / cm ² ), the load pressure is guided to one pressure chamber 65 of the pressure reducing valve section 24, and the pressure reducing valve section 24 strokes with the pressure of the one pressure chamber 65, but the other pressure chamber 66. When the pressure rises to the pressure in one pressure chamber 65 (that is, the load pressure), it is closed by a weak spring 69 and abuts against the check valve portion 23. In any case, the pressure reducing valve section 2
4 until the pressure in one pressure chamber 65 and the pressure in the other pressure chamber 66 are equal.
When the pressures in the two pressure chambers 65 and 66 become equal, the spring 6 is closed by a weak spring 69 and abuts on the check valve portion 23. As a result, the pressure in the load pressure detection path 82 becomes equal to the load pressure, and the pump discharge pressure is adjusted by the pump adjustment direction control valve 85 to a certain differential pressure (here, 20 kg / c).
The pressure is controlled to be higher than the pressure in the load pressure detecting path 82 by m ² ). The pump discharge pressure is controlled by the check valve unit 23.
, The differential pressure (= 20 kg / cm ² ) is maintained between the inlet pressure and the outlet pressure (= load pressure) of the directional control valve 22. become. Therefore, the flow rate supplied to the actuator 88 is controlled only by a change in the opening area of the throttle between the inlet side and the outlet side according to the stroke of the direction control valve 22. When the directional control valve 22 is to be stroked, the conduit 89 or 90 of the actuator 88 and the second
The oil passage 53 is connected, while the second oil passage 53 is connected to one pressure chamber 65 of the pressure reducing valve portion 24. In the pressure reducing valve portion 24, the load pressure is equal to the pilot pressure (set of the pressure reducing valve portion). Pressure), so that the pressure is not released. That is, when the directional control valve 22 is stroked, the load 88 is released.
There is no natural descent.

The load pressure detecting path 82 is connected to the pressure reducing valve section 2 of the pressure compensating valve 25 disposed on the other directional control valve 22.
4 is connected to the other pressure chamber 66, but one pressure chamber 65 of the pressure reducing valve section 24 is connected to the tank 86 by the neutral position A of the directional control valve 22, so that it is used for introducing load pressure. The pressure in the first oil passage 53 is zero, and
The pressure reducing valve 24 urges the check valve 23 in the closing direction by the internal pressure. On the other hand, since the pump discharge pressure is guided from the pump discharge passage 21 to the pressure chamber a in the opening direction of the check valve portion 23, the differential pressure (== the pressure difference between the pump discharge pressure and the pressure in the load pressure detection passage 82) as a whole. 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, but the stroke is slightly increased and the pressure of the pump port 44 becomes the differential pressure (= 20 k).
g / cm ² ), the receipt is performed by the weak spring 69, and as a result, the pressure reducing valve section 24 does not stroke until the stroke end, and does not affect the hydraulic control of the direction control valve 22 at all. .

When any of the direction control valves 22 is to be 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 both the directional control valves 22 are stroked to the first pressure oil supply position B, and the respective pump ports 44, the respective conduits 89, and the respective first hydraulic passages 53 for guiding the load pressure are connected. One of the pressure reducing valves 24 operates until the pressure in the pressure chamber 66 becomes equal to the pressure in the one pressure chamber 65, and the other pressure reducing valve 24 operates to reduce the pressure in the pressure chamber 66 to one of the pressure chambers 65. , Respectively, until they equal the internal pressure.
Now, it is assumed that the load pressure of the left actuator 88 among the load pressures of the two actuators 88, 88 is larger. Assuming that the load pressure of the left actuator 88 is 100
(Kg / cm ² ), and the load pressure of the right actuator 88 is 10 (kg / cm ² ). The load pressure detection path 82
Since it is connected to the tank 86 via the throttle 91, the pressure in the load pressure detection path 82 is zero before the directional control valve stroke. Therefore, each pressure reducing valve section 24 also strokes by the pressure in the first oil passage 53 for load pressure detection, and the pump discharge pressure communicates with the pressure in the pressure detection conduit 34. When the pressure in the load pressure detection path 82 rises to the pressure (10 kg / cm ² ) in the conduit 90 of the right actuator 88 on the low pressure side, first, the pressure reducing valve section 24 of the right pressure compensating valve 25.
Closes. The pressure reducing valve portion 24 of the pressure compensating valve 25 on the left side remains in the stroke, and the pressure in the load pressure detecting path 82 increases until it becomes equal to the pump discharge pressure (20 kg / cm ² ). At this time, the left actuator 88 on the high pressure side
Pressure of the pump port 44 of the directional control valve 22 is 100
(Kg / cm ² ), and the check valve portion 23 of the pressure compensating valve 25 is closed and dissociated from the pressure reducing valve portion 24.
On the other hand, the pressure reducing valve portion 24 of the pressure compensating valve 25 is provided with two pressure chambers 6.
Pressure difference between 5 and 66 (20-10 = 10kg / c
At m ² ), the check valve 23 is urged in the closing direction. On the other hand, since the pressure (pump discharge pressure) in the pressure chamber a in the opening direction of the check valve portion 23 is 20 (kg / cm ² ),
As a result, the check valve 23 is opened until the pressure of the pump port 44 of the direction control valve 22 becomes 10 (kg / cm ² ), and then the receipt is performed by the weak spring 69. By the pump control directional control valve 85, a certain differential pressure (20 kg / c
m ² ), the pressure in the load pressure detection path 82 (20 kg /
cm ² ), the pump discharge pressure is controlled to a pressure higher than
0 kg / cm ² ). Also at this time, the high pressure side pressure compensating valve 25
The pressure in the load pressure detection path 82 is 40 (k) while the check valve section 23 is closed and the pressure reducing valve section 24 is stroked.
g / cm ² ). On the other hand, the pressure reducing valve portion 24 of the pressure compensating valve 25 on the low pressure side has a pressure difference (= 30 kg / cm ² ) between the load pressure detecting path 82 and the first oil path 53 for introducing the load pressure. Urges the check valve portion 23 in the closing direction, and as a result, the pressure of the pump port 44 of the directional control valve 22 remains at 10 kg / cm ² . In this manner, the pressure in the load pressure detection path 82 and the pump discharge pressure continue to increase, and eventually the pump discharge pressure becomes the load pressure (100 kg / c) of the high-pressure side actuator 88.
m ² ), the pressure of the high-pressure side pressure compensating valve 25 is reduced.
The pressure in the two pressure chambers 65 and 66 of the valve portion 24 is 1
It becomes 00 kg / cm ^{2 and} comes into contact with the close check valve portion 23 by the weak spring 69. At this time, the pressure reducing valve portion 24 of the pressure compensating valve 25 on the low pressure side has a pressure difference (100−10 = 90 k) between the load pressure detecting path 82 and the first oil path 53 for introducing the load pressure.
g / cm ² ) to urge the check valve portion 23 in the closing direction. As a result, the pressure at the pump port 44 of the directional control valve 22 on the low pressure side remains at 10 kg / cm ² . Again, the pump discharge pressure becomes 1 by the pump adjustment direction control valve 85.
It is controlled at 20 (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 the pressure difference between the two pressure chambers a and b of the check valve portion 23 causes For the first time, the check valve section 23 opens and the pump discharge pressure (1
20 kg / cm ² ) is the pump port 4 of the directional control valve 22.
It is led to 4. On the other hand, the pressure reducing valve section 24 of the pressure compensating valve 25 on the low pressure side is connected to the load pressure detecting path 82 and the first oil path 5 for introducing the load pressure.
3, the check valve portion 23 is continuously urged in the closing direction by the pressure difference (= 90 kg / cm ² ).
The pressure in the pressure chamber a in the opening direction is 120 (kg / c).
m ² ), the check valve section 23 and the pressure reducing valve section 24 are pressure-balanced with the pressure at the inlet port 44 of the directional control valve 22 being 30 (kg / cm ² ) (120-90). That is, the check valve section 23 and the pressure reducing valve section 24
Strokes slightly, and at the check valve portion 23,
It is in a state of being squeezed so as to be 120 kg / cm ² to 30 kg / cm ² . For the first time, the hydraulic control system is balanced and the pump port 4 of the directional control valve 22 on the high pressure side is
4 is 120 kg / cm ² , low pressure side directional control valve 2
2 is 30 kg / cm ² , that is, the difference between the inlet pressure and the outlet pressure (load pressure) of the two directional control valves 22 is maintained at 20 kg / cm ² . The two directional control valves 22 can control the flow rate supplied to the actuators 88 only by the stroke.

When the total flow rate required for each of the actuators 88, 88 is equal to or greater than the maximum discharge flow rate of the hydraulic pump 20 . Now, the load pressure and the required flow rate of the actuators 88, 88 are set to 100 kg by the left actuator 88.
/ Cm ² , 501 / min, right actuator 88
Is 10 kg / cm ² and 501 / min. Hydraulic pon
When the maximum discharge flow rate of the pump 20 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 every 501 / min. Next, the hydraulic pump 20
It is assumed that the maximum discharge amount has reached 701 / min. As described above, the inlet pressure of the two directional control valves 22, 22 is 120 kg /
cm ² and 30 kg / cm ² , the flow rate to the high-pressure side directional control valve 22 is from 501 / min to 201 / min.
Reduced to The flow rate to the low pressure side directional control valve 22 is 501 /
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 high-pressure side directional control valve 22 drops from 20 kg / cm ² by the reduced flow rate. Now the differential pressure is 14k
g / cm ² , ie, the inlet pressure is 120 kg / cm ²
To 114 (100 + 14) kg / cm ² . At this time, since the pressures in the two pressure chambers 65 and 66 of the pressure reducing valve portion 24 of the pressure compensating valve 25 remain at 100 kg / cm ² , the pressure reducing valve portion 24 comes into contact with the check valve portion 23 by the weak spring 69. And the pressure in 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 direction in which the check valve 23 opens, that is, the pump discharge pressure is 120 kg / cm ² while the check valve 23 remains open (stroke end). 114kg from cm ²
/ Cm ² . At this time (when the pump discharge flow rate is insufficient)
Therefore, the pump discharge pressure is no longer controlled by the pump adjusting direction control valve 85. On the other hand, the two pressure chambers 65 and 66 of the pressure reducing valve section 24 of the pressure compensating valve 25 on the low pressure side have a pressure of 100 kg / c.
m ² , 10 kg / cm ² and the differential pressure 90 kg / cm ²
In cm ² , the check valve portion 23 is continuously urged in the closing direction . On the other hand, since the pressure in the pressure chamber a in the direction in which the check valve portion 23 opens, that is, the pump discharge pressure has been reduced to 114 kg / cm ² , the pressure chamber b in the direction in which the check valve portion 23 closes.
The check valve section 23 and the pressure reducing valve section 24 are pressure-balanced in a state where the internal pressure is reduced from 30 kg / cm ² to 24 kg / cm ² . Therefore, the differential pressure between the inlet pressure and the outlet pressure of the low pressure side directional control valve 22 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 accordingly 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
The hydraulic control system is balanced in a state where the supply amounts to 8, 88 are both distributed at 351 / min.

When there are three or more actuators loaded by one hydraulic pump 20 . Even when there are three or more actuators, a 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. The operation based on the above-described operation principle can be realized even when the number of actuators is three or more, by merely communicating all the differences by the load pressure detection path 82.

[0015]

With such a pressure oil supply device, the first and second load pressure detection ports 45 and 46 and the first and second load pressure detection ports 45 and 46 based on the stroke of the main spool 49 of the direction switching valve 22 are provided.
The flow rate proportional to the opening area of the second actuator ports 34 and 35 is the first flow rate regardless of the load pressure of the actuator 88.
-It is supplied to the second actuator ports 34, 35.
For this reason, when supplying the pressure oil to the left and right traveling hydraulic motors of the hydraulically driven vehicle, if the opening areas of the left and right directional control valves 22 are different due to processing errors, the flow rate supplied to the left and right traveling hydraulic motors is reduced. The driver turns around instead of straight ahead.

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

[0017]

When the spool 64 of the pressure reducing valve section 24 slides against the spring 69 with the pressure in the first pressure chamber 65, the first pressure chamber 65 and the second port 42 are communicated. And the first port 39 of the pair of valve blocks 30, 30.
Is connected to the discharge path 21 of the hydraulic pump 20 and the second port 4
2. A pressure oil supply device that communicates with each other and connects the third port 43 to the load pressure detection path 82, respectively.

[0018]

The main pump 49 of the directional control valve 22, 22 of the pair of valve blocks 30, 30 is simultaneously slid in the same direction so that the discharge pressure of the hydraulic pump 20 is applied to each of the first or second actuator ports 34, 35. When oil is supplied, each pressure reducing valve section 2
The spool 64 of the fourth device is moved by the pressure in the first pressure chamber 65 to the spring 69.
The first pressure chamber 65 and the second port 4
2 communicate with each other, the second of the left and right valve blocks 30
The pressure of the port 42 becomes the same, and the left and right valve blocks 3
Even if the opening areas of the directional control valves 22 and 22 of 0 and 30 are different due to processing errors and the like, the same flow is applied to the left and right actuators 88.
Can supply a quantity of pressurized oil .

[0019]

Embodiment An embodiment of the present invention will be described with reference to FIG. The same members as those in the related art have the same reference numerals. The main spool 49 has an intermediate small-diameter portion 12 that communicates and shuts off the pump port 44 and the first and second load pressure detection ports 45 and 46.
0 is formed. The third port 43 of the pressure reducing valve section 24 and the second pressure chamber 66 are shut off by the spool 64 and the third port 43
Slit-shaped opening 1 for communicating and blocking between the first port 42 and the second port 42
00 is formed on the outer peripheral surface of the spool 64 and the third port 43
Is connected to the load pressure detecting path 82. Blind hole 6 of spool 64
7 has a stepped shape, the sheet 68 has a shape having a blind hole 68a and an annular concave portion 68b, and the sheet 68 abuts on the outward stepped portion 67a of the blind hole 67 and is fixed. A check valve 101 is pressed against the periphery of the opening of the blind hole 68a of the seat 68 by a spring 102 to form a pressure chamber 103 between the blind hole 68a and the check valve 101. The throttle 104 communicates with the second pressure chamber 66, and the second throttle 105 communicates with the annular recess 68b.
Of the check valve 1
The spring chamber 107 of No. 01 is opened to the second port 42 by the throttle 108. The first pressure chamber 65 is inserted into the notch 1 of the spool 64.
09 and free piston 68 and check valve 1 with small hole 110
01.

As shown in FIG. 5, the left and right valve blocks 30,
The second ports 42 of the pressure-reducing valve portions 24, 24 are connected to each other by a passage 111.
The actuator 88 communicating with the first and second actuator ports 34 and 35 is a left and right traveling hydraulic motor, and the discharge path 21 of the hydraulic pump 20 is connected to the first port 39 of the left and right valve blocks 30 respectively. Connected.

Next, the operation will be described. When traveling straight. As shown in FIG. 4, when the main spool 49 of the directional control valve 22 of the left and right valve blocks 30 is moved to the left, the discharge pressure oil of the hydraulic pump 20 is discharged from the first port 39, the pump port 44 , the intermediate small diameter section 120, One port 88a of the actuator 88 from the left notch 121, the first load pressure detection port 45, the communication passage 122, the second load pressure detection port 46, the left notch 123, the second small diameter portion 51, and the second actuator port 35.
Return oil from the other port 88b
The fluid flows out from the actuator port 34, the first small diameter portion 50 , and the left notch 124 to the first tank port 47. The load pressure of the actuator 88 is the second actuator port 3
5. Act on the first pressure chamber 65 from the second load pressure detection port 46 and the passage 58 to push the spool 64 rightward to cause a stroke. At this time, the pressure of the second port 42 is introduced into the spring chamber 107 of the check valve 101 by the throttle 108 of the spool 64 and acts on the left side surface of the check valve 101. On the other hand, the pressure in the third port 43 flows into the pressure chamber 103 between the check valve 101 and the blind hole 68a of the seat 68 from the throttle 106 of the spool 64, the annular recess 68b, and the second throttle 105 of the seat 68. Acts on the right side of valve 101. Since the pressure of the second port 42 and the pressure of the third port 43 are substantially the same, the check valve 101 is pressed against the seat 68 by the spring 102 and held.

As a result, the notch groove 109 of the spool 64 opens to the second port 42 and communicates with the passage 111 as shown in FIG. 5, so that the load pressure of the left and right actuators 88, 88 connected to the left and right valve blocks 30, 30 is increased. Is the second port 42
Since the second port 42 communicates with the third port 43 through the opening 100, the load pressure is supplied to the load pressure detecting circuit 82. When the pressure supplied to 88a, that is, the load pressure becomes the same, the vehicle can travel straight.

At the time of right and left turning traveling. When the main spool 49 of the direction control valve 22 of the right valve block 30 is slid rightward toward the neutral position from the above-described state, the opening area between the second load pressure detection port 46 and the second actuator port 35 decreases. Therefore, the flow rate flowing to one port 88a of the right actuator 88 decreases. As a result, the load pressure of the right actuator 88 decreases and the right valve block 3
0, the pressure in the first pressure chamber 65 of the pressure reducing valve section 24 decreases, and the spool 64 of the second pressure chamber 66 is supplied to the second pressure chamber 66 by the load pressure detection path 82 in the second pressure chamber 66 of the left valve block 30.
Pressed to the left by the load pressure (that is, the control pressure) inside
Since the port 42 and the first pressure chamber 65 are not communicated with each other by the cutout groove 109, the load pressure on the right actuator 88 is low and the load pressure on the left actuator 88 is high without the left and right load pressures being equal. Turn right.
At this time, the load pressure of the passage 88, the second port 42, and the load of the actuator 88 on the left side of the throttle 108 is introduced into the spring chamber 102 of the check valve 101 of the pressure reducing valve section 24 of the right valve block 30, so that the left side of the check valve 101 Act on the surface.
On the other hand, on the right side of the check valve 101, a load pressure detecting path 8 is provided.
2, third port 43, throttle 106 of spool 64, second
The control pressure acts from the throttle 105, but this control pressure is almost equal to the load pressure of the left actuator 88, so that the check valve 101 is pressed against the free piston 68.

FIG. 6 is a cross-sectional view of a state in which a plurality of valve blocks 30 are combined and connected by joining their left and right side surfaces 32 and 33 to each other. For convenience of explanation, the valve blocks 30 are first, second, and third.・ Fourth, fifth and sixth valve blocks 30a, 30
b, 30c, 30d, 30e, and 30f. The second and third valve blocks 30b and 30c are valve blocks of the hydraulic motor for right and left traveling shown in FIG. 5, and a first block 130 is joined and connected to the first valve block 30a. Main oil hole 131 communicating with 1 port 39
The main oil hole 131 communicates with the oil hole 133 via the check valve 132, and the oil hole 133 communicates with the second port 42 of the first valve block 30a at the port 134,
The third port 43 of each valve block 30 communicates with a port 135, the second port 42 of the second and third valve blocks 30b and 30c communicates with a port 136, and the fourth, fifth, and sixth valve blocks. The second ports 42 of 30d, 30e, and 30f communicate with each other at a port 137, and the first ports 39 of each valve block 30 communicate with each other. The other block 139 is joined and connected to the sixth valve block 30f, and the other block 139 is connected to the first passage 140 and the second passage 139.
A passage 141 is formed, and the first passage 140 is the sixth passage.
The port 142 communicating with the first port 39 and the second port 42 of the valve block 30f communicates, and the second communication passage 141 connects the load pressure detection path 82 with the port 143 communicating with the third port 43 of the sixth valve block 30f. Communicating.

In FIG. 4, a small-diameter portion 150 is formed in the spool 60 of the check valve portion 23 for connecting and disconnecting the first port 39 and the pump port 44, and the pressure chamber 151 for pushing the spool 60 rightward and the first port 39 are formed. Partition and spool 6
0 through the damper throttle 152 and the communication hole 153.
It communicates with port 39. Thus, when the spool 60 slides rightward and leftward, the first port 39 and the pressure chamber 151 slide.
Therefore, the pressure oil flows through the damper throttle 152 between the two positions, so that the spool 60 can be prevented from suddenly sliding left and right.

[0026]

When the main spools 49 of the directional control valves 22, 22 of the left and right valve blocks 30, 30 are slid in the same direction by the same stroke, the first pressure of the pressure reducing valve portions 24 of the left and right valve blocks 30, 30 is increased. The chamber 65 communicates with the second port 42,
Moreover, since the second ports 42 of the left and right valve blocks 30, 30 are in communication with each other, the left and right valve blocks 30, 3,
0, the pressures of the second ports 42 become equal, and even if the opening areas of the directional control valves 22, 22 of the left and right valve blocks 30, 30 are different due to processing errors and the like, the first and second valve blocks 30, 30 are left and right. Discharge pressure oil of the hydraulic pump 20 can be supplied to the actuator ports 34 and 35 at the same flow rate. Therefore, by connecting the first and second actuator ports 34 and 35 of the left and right valve blocks 30 and 30 to the left and right traveling hydraulic motors, it is possible to supply the same flow rate to the left and right traveling motors and travel straight.

[Brief description of the 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 filed earlier.

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

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

FIG. 5 is an explanatory diagram showing a connection state of left and right valve blocks.

FIG. 6 is a cross-sectional view of a state where a plurality of valve blocks are joined and combined.

[Explanation of symbols]

Reference numeral 20: hydraulic pump, 21: discharge path, 22: directional 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, 109 ... notched groove.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-53-41681 (JP, A) JP-A-5-332308 (JP, A) JP-A-5-332309 (JP, A) JP-A-4- 351384 (JP, A) Japanese Utility Model 5-30503 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) F15B 11/00-11/22

Claims (1)

(57) [Claims] 1. A spool port 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 is formed 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.
A main spool 49 for connecting and disconnecting each port is inserted into the directional control valve 22 by inserting the first port 39 and the check valve hole 37 opened in the check valve hole 37 into the valve block 30. An oil passage 56 communicating with the first port 39 is formed in the check valve hole 37. The first port 39 communicates and shuts off the oil passage 56, and a spool 60 stopped at the shut-off position is inserted into the check valve portion 23 to form the check valve portion 23. The valve block 30 has a second opening that opens to the pressure reducing hole 38.
The third ports 42 and 43 are formed, and the pressure reducing valve holes 38 are formed.
A first pressure chamber 65 and a second pressure chamber 66 are formed by inserting a spool 64 into the first pressure chamber 65, the first pressure chamber 65 communicates with the second load pressure detection port 46, and the second pressure chamber 66 is connected to the third port 43. , The spool 64 is urged in one direction by a spring 69 to press and hold the spool 60 of the check valve portion 23 at the shut-off position to form the pressure reducing valve portion 24. The pressure reducing valve portion 24 and the check valve portion A pressure compensating valve 25 is provided at 23, and the first pressure chamber 65 communicates with the second port 42 when the spool 64 of the pressure reducing valve section 24 is pressed in a direction against the spring 69 by the pressure in the first pressure chamber 65. The hydraulic pump 2 is connected to the first port 39 of the pair of valve blocks 30.
0 discharge path 21, and the second
The ports 42 communicate with each other, and the third
A hydraulic supply device characterized in that the port (43) communicates with a load pressure detector (82).