JPH064404U - Pressure oil supply device - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] To enable a part of the return oil from the actuator to be supplied to the actuator. A main spool 49 is inserted into a spool hole 31 of a valve block 30 to form a directional control valve 22, and a spool 60 is inserted into a check valve hole 37 to form a check valve portion 23.
The spool 64 is fitted into the pressure reducing valve hole 38, and the first pressure chamber 6
5 and the second pressure chamber 66. The first pressure chamber communicates with the load pressure detection port of the directional control valve, the second pressure chamber communicates with the second port 43, and the spool 64 is pushed toward the spool 60 side by the spring 69 to form the pressure reducing valve portion 24. The pump discharge passage 21 of the hydraulic pump 20 is connected to the pump port 39 and the first port 42, and the second port load pressure detection circuit 82 is connected to form the pressure compensating valve 25 by the check valve portion and the pressure reducing valve portion.
A second oil passage 54 is formed in the main spool and communicates with the second actuator port 35 to supply a part of the return oil to the first actuator port 34.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a hydraulic oil supply device that supplies the hydraulic oil discharged from one hydraulic pump to a plurality of actuators.

[0002]

[Prior 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 and 13 are connected in parallel to a discharge conduit 2 of a hydraulic pump 1, and directional control valves 5 and 15 are connected to outlet conduits 4 and 14 of each pressure compensating valve 3 and 13. The output sides of the directional control valves 5 and 15 are connected to the actuators 6 and 16, respectively, and 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 to control the direction. It is a pressure oil supply device that is structured to be pushed in the closing direction by the 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, and moreover, the shuttle valve 7 is the actuator. Only one less than 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 released by the blowout in the shuttle valve 7, and the pressure in the other conduit 8 is pushed. Therefore, when the shuttle valve 7 is switched, the actuator 6 is transiently lowered 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 provided with a plurality of directional control valves 22 in a discharge passage 21 of a hydraulic pump 20, and a check valve portion 23 and a pressure reducing valve are provided on the inlet side of each directional control valve 22. A pressure compensating valve 25 composed of a portion 24 is provided respectively, and the directional control valve 22 and the pressure compensating valve 25 are constructed 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. The first and second actuator ports 34 and 35 are formed so as to open on the upper surface 36, and the check valve hole 37 opened on the left side surface 32 and the depressurization opening on the right side surface 33 are formed near the lower part of the valve block 30. The valve hole 38 is concentrically formed, and the pump port 39 opening to the check valve hole 37 is formed to open on the front and rear surfaces, and the first and second ports 42 opening to the pressure reducing valve hole 38 are formed. , 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 respective pumps, the first and second ports 39, 42, 43 are made to communicate with each other. Ru .

In the valve block 30, an input port 44 opened in a spool hole 31, first and second load pressure detection ports 45 and 46, first and second actuator ports 34 and 35, first and second The tank ports 47, 48 are formed, the first and second small diameter portions 50, 51 and the communication groove 52 are formed in the main spool 49 fitted in the spool hole 31, and the first spool 49 is formed in the first spool 49. A first oil passage 53 that constantly connects the second load pressure detection ports 45 and 46 and a second oil passage 54 that connects and disconnects the second load pressure detection port 46 and the second tank port 48 are formed. Is held in the neutral position where the second load pressure detection port 46 and the second tank port 48 communicate with each other by shutting off each port with a spring and sliding the spool 49 to the right to the second small diameter. Part 51 The actuator port 35 communicates with the second tank port 48, the communication groove 52 allows the input port 44 to communicate with the second load pressure detection port 46, and the first small diameter portion 50 allows the first actuator port 34 to communicate with the first load. It is in the first pressure oil supply position that communicates with the pressure detection port 45 and the second load pressure detection port 46 and the second tank port 48 are shut off. Communicates the first actuator port 34 with the first tank port 47, the communication groove 52 communicates the input port 44 with the first load pressure detection port 45, and the second small diameter portion 51 communicates with the second actuator port 35. The directional control valve 22 is located at a second pressure oil supply position that communicates with the second load pressure detection port 46 and that shuts off the second load pressure detection port 46 and the second tank port 48.

The check valve hole 37 is opened to the input port 44 by the oil passage 56, and the check valve hole 37 is fitted with a valve 60 that cuts off the communication between the pump port 39 and the input port 44. Numeral 60 is a stopper rod 62 provided on the plug 61, which is regulated so as not to slide to the left from the illustrated position and is held at the cutoff position to form the check valve portion 23. The pressure reducing valve hole 38 communicates with the second load pressure detecting port 46 through the third port 57 and the oil passage 58, and the spool 64 is fitted into the pressure reducing valve hole 38 to connect the first pressure chamber 65 and the second pressure chamber 65. A pressure chamber 66 is formed, the first pressure chamber 65 communicates with the third port 57, the second pressure chamber 66 communicates with the second port 43, and a blind piston 68 inserted in the blind hole 67 of the spool 64 and a blind piston 68. A spring 69 is provided between the free piston 68 and the bottom of the hole 67 so that the free piston 68 abuts on the plug 70, and a push rod 71 integrally provided on the spool 64 projects from the through hole 72 so that the valve 60 is stopped by the stopper rod. 62, and the spool 64 is formed with a fine hole 73 for communicating the first port 42 with the blind hole 67 to form the pressure reducing valve portion 24. The pressure reducing valve portion 24 and the check valve portion 23 are connected to each other. Pressure compensating valve 25.

As shown in FIG. 2, the discharge passage 21 of the hydraulic pump 20 is communicated with the pump port 39 and the first port 42, and the load pressure detection passage 82 is connected to the second port 43. An actuator 88 is connected to the 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. The oil sucked up from the tank 86 by the hydraulic pump 20 is guided through the discharge passage 21 to the pressure chamber a in the opening direction of the check valve portion 23. At this time, since the pressure chambers 65 and 66 of the pressure reducing valve portion 24 both communicate with the tank 86, the pressures of the pressure chambers 65 and 66 are both zero, so the pressure reducing valve portion 24 is pressed by the weak spring 69. The rod 71 is only in contact with the check valve portion 23. 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 detecting path 82. Now, assuming that this differential pressure is 20 kg / cm ² , the pressure in the load pressure detection path 82 is zero, so the pump discharge pressure rises to 20 kg / cm ^2, and at the same time, the pump discharge pressure enters the pressure chamber a of the check valve section 23. After flowing in, the stroke is made 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, and when they become equal, the weak spring 69 makes a receipt. The pressure reducing valve portion 24 communicates the pump discharge passage 81 and the pressure chamber 66 only at the stroke end, while the check valve portion 23 communicates the pump discharge passage 81 and the outlet side before reaching the stroke end. When the control valve 22 is in the neutral position A, the pump discharge passage 21 and the pressure chamber 66 do not communicate with each other, and the pressure in the pressure chamber 65 remains zero.

When only one of the directional control valves 22 is stroked to the first 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 input 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 larger than the pump discharge pressure (20 kg / cm ² ), the check valve portion 23 receives the pressure in the pressure chamber b. Therefore, 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 introduced into the pressure chamber 65 of the pressure reducing valve portion 24 from the first oil passage 53 and the passage 58. 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 through the throttle of the pressure reducing valve unit 24, the pump discharge passage 21 And the load pressure detection path 82 communicate with each other. 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 portion 23, and the pressure is reduced to one of the pressure reducing valve portions 24. Since the pressure reducing valve portion 24 is guided to the pressure chamber 65, the pressure reducing valve portion 24 remains in a stroke even when the other pressure chamber 66 communicates with the pump discharge passage 21. On the other hand, when the pressure (load pressure) in the conduit 41 is lower than the pump discharge pressure (= 20 kg / cm ² ), the load pressure is guided to one pressure chamber 65 of the pressure reducing valve portion 24, and the pressure reducing valve portion 24 is Although the stroke is made by the pressure of one pressure chamber 65, when the pressure of the other pressure chamber 66 rises to the pressure of one pressure chamber 65 (that is, the load pressure), the weak spring 69 closes and abuts against the check valve portion 23. In any case, the pressure reducing valve section 24 makes the pump discharge passage 21 and the pressure chamber 66 communicate with each other until the pressure inside the one pressure chamber 65 and the pressure inside the other pressure chamber 66 become equal to each other. If the pressures in 66 become equal, a weak spring 69 makes contact with the closing 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 directional control valve 85 by a certain differential pressure (here, 20 kg / cm ² ). The pressure is controlled to be higher than the pressure in 82. This pump discharge pressure is guided to the input 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 the load pressure are connected, while the second oil passage 53 is connected to the pressure of one of the pressure reducing valve portions 24. Although it is connected to the chamber 65, the load pressure in the pressure reducing valve section 24 is used only as pilot pressure (set pressure of the pressure reducing valve section), so the pressure is not lost, that is, the directional control valve 22 is When the stroke is made, there is no spontaneous lowering of the actuator 88 due to the release of the load pressure.

The load pressure detection path 82 is also connected to the other pressure chamber 66 of the pressure reducing valve portion 24 of the pressure compensating valve 25 arranged in the other directional control valve 22, but the pressure reducing valve portion 24 Since one of the pressure chambers 65 is connected to the tank 86 by the neutral position A of the directional control valve 22, the pressure in the first oil passage 53 for introducing the load pressure is zero, and therefore the pressure chamber 66 is The pressure reducing valve 24 urges the check valve 23 in the closing direction. On the other hand, since the pump discharge pressure is introduced from the pump discharge passage 81 to the pressure chamber a in the direction of opening the check valve portion 24, as a whole, the pressure difference between the pump discharge pressure and the pressure in the load pressure detection passage 82 ( = 20 kg / cm ²⁾ by it is a stroke in the opening direction of the check valve 23 and the pressure reducing valve section 2 4 check valve unit 23, slightly stroke and the pressure input port 44 is the differential pressure (= 20kg / cm ²⁾ In this case, the weak spring 69 causes a receipt, and as a result, the pressure reducing valve portion 24 does not stroke to the stroke end, and there is no influence on the hydraulic control of the directional control valve 22 side.

When stroke of any of the directional control valves 22 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 respective input ports 44, the respective conduits 89, and the respective first oil passages 53 for introducing the load pressure are respectively connected. One of the pressure reducing valve portions 24 has the pressure in the pressure chamber 66 equal to the pressure in the one pressure chamber 65, and the other pressure reducing valve portion 24 has the pressure in the pressure chamber 66 equal to that of the one pressure chamber 65. It continues to stroke to the end of each stroke until it becomes equal to the pressure in 65. Now, assume that the load pressure of the left actuator 88 is larger than the load pressure of the two actuators 88, 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 section 24 also strokes due to the pressure in the first oil passage 53 for detecting the load pressure, 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 actuator 88 on the right side, which is the low pressure side, first, the pressure reducing valve portion 24 of the pressure compensating valve 25 on the right side closes. . The pressure reducing valve portion 24 of the pressure compensating valve 25 on the left side is still in a stroke, and the pressure in the load pressure detecting path 82 rises until it becomes equal to the pump discharge pressure (20 kg / cm ² ). At this time, the pressure at the input port 44 of the directional control valve 55 of the left-side actuator 88, which is 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 dissociated from. On the other hand, the pressure reducing valve portion 24 of the pressure compensating valve 25 urges the check valve portion 23 in the closing direction by the difference in pressure between the two pressure chambers 65 and 66 (20-10 = 10 kg / cm ² ). 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 ), and as a result, the pressure force of the input port 44 of the directional control valve 22 is 10 (kg / Cm ² ), the check valve portion 23 is opened, and then a receipt is made by the weak spring 69. The pump adjusting directional control valve 85 controls the pump discharge pressure to a pressure higher than the pressure (20 kg / cm ² ) in the load pressure detection path 82 by a certain pressure difference (20 kg / cm ² ) (40 kg / cm ² ). ² ). Also at this time, the pressure in the load pressure detection path 82 becomes 40 (kg / cm ² ) while the check valve portion 23 of the high-pressure side pressure compensating valve 25 remains closed and the pressure reducing valve portion 24 remains stroked. The pressure reducing valve portion 24 of the pressure compensating valve 25 on the low pressure side is closed in the direction in which the check valve portion 23 is closed due to the pressure difference (= 30 kg / cm ² ) in the load pressure detecting passage 82 and the first oil passage 53 for introducing the load pressure. It is energized so that the pressure at the input port 44 of the directional control valve 22 remains at 10 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 The pressures in the two pressure chambers 65 and 66 of the pressure reducing valve section 23 of the pressure compensating valve 25 are both 100 kg / cm ² , and the weak spring 69 makes contact with the closing check valve section 23. At this time, the pressure reducing valve portion 24 of the pressure compensating valve 25 on the low pressure side has a check valve portion due to a pressure difference (100-10 = 90 kg / cm ² ) in the load pressure detecting passage 82 and the first oil passage 53 for introducing the load pressure. 23 is urged in the closing direction, and as a result, the pressure of the input port 44 of the directional control valve 22 on the low pressure side remains 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 is opened, and the pump discharge pressure (120 kg / cm ² ) is guided to the input 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 ) between the load pressure detecting passage 82 and the first oil passage 53 for introducing the load pressure. However, since the pressure in the pressure chamber a in the opening direction of the check valve portion 23 became 120 (kg / cm ² ), the pressure at the inlet port 44 of the directional control valve 22 was 30 (kg / cm ² ). cm ² ) (120-90), the check valve portion 23 and the pressure reducing valve portion 24 are pressure balanced. That is, the check valve portion 23 and the pressure reducing valve portion 24 make a slight stroke, and the check valve portion 23 is in a state of being squeezed to be 120 kg / cm ² to 30 kg / cm ² . For the first time, this hydraulic control system is balanced so that the pressure of the input port 44 of the high-pressure side directional control valve 22 is 120 kg / cm ² and the pressure of the input port 44 of the low-pressure side directional control valve 22 is 30 kg / cm 2. ² , that is, the difference between the inlet pressure and the outlet pressure (load pressure) of the two directional control valves 22 and 22 is maintained at 20 kg / cm ² , so that the two directional control valves 22 and 22 are In both cases, the flow rate supplied to the actuators 88, 88 can be controlled only by the stroke amount.

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 the required flow rate of the actuator 88, 88 left actuator 88 is ^{100kg / cm 2, 501 / min} , the right actuator 88 and ^{10kg / cm 2, 501 / min} . When the maximum discharge flow rate of the hydraulic pump 80 is 1001 / min or more, the difference between the inlet pressure and the outlet pressure of the directional control valves 22, 22 is kept constant (= 20 kg / cm ² ) as described above. , 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. Since the inlet pressure of the two directional control valves 22 and 22 are described above ^{120kg / cm 2, 30kg / c} m 2, flow to the high pressure side of the directional control valve 22 is reduced to 201 / min from 501 / min. The flow rate to the low-pressure side directional control valve 22 remains at 501 / min. Assuming that 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 by 20 kg / cm ^{2 due} to the decrease in the flow rate. Go down. Now, assume that the differential pressure is 14 kg / cm ² , that is, the inlet pressure is reduced from 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 remain at 100 kg / cm ² , and therefore the pressure reducing valve portion 24 is checked by the weak spring 69. If the pressure inside the pressure chamber b in the closing direction of the check valve portion 23 decreases from 120 kg / cm ² to 114 kg / cm ² , the check valve portion 23 remains open (stroke end). ), the direction of the pressure in the pressure chamber a to open the check valve unit 23, i.e., the pump discharge pressure is reduced to 120 kg / cm ² or et 114 kg / cm ^2. At this time (when the pump discharge flow rate is insufficient), the pump discharge pressure is not controlled by the pump adjustment 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 remain 100 kg / cm ² and 10 kg / cm ² , and the differential pressure of 90 kg / cm ² causes the check valve portion 63 to be Continue to push in the closing direction. 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 in the pressure chamber b in the closing direction of the check valve portion 23 is 30 kg / cm 2. ^The check valve portion 23 and the pressure reducing valve portion 24 balance the pressure in the state where the pressure is reduced from ² to 24 kg / cm ² . Therefore, the differential pressure between the inlet pressure and the outlet pressure of the directional control valve 22 on the low pressure side is reduced from 20 kg / cm ² to 14 kg / cm 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, in the state where the differential pressure between the inlet pressure and the outlet pressure of the directional control valves 22 and 22 is equal, and the supply amounts to the two actuators 88, 88 are both divided into 351 / min, the hydraulic control system is controlled. Balance.

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

[0015]

[Problems to be solved by the device]

 With such a pressure oil supply device, the return oil from the actuator 88 flows out to the tank port, and only the discharge pressure oil of the hydraulic pump 20 is supplied to the actuator 88. Therefore, in the case of an actuator that requires a large flow rate, The amount of discharge must be increased, which results in power loss and cost disadvantage.

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

[0017]

[Means for Solving the Problems]

 The main spool 49 includes a first actuator port 34 (or a second actuator port 35), a first tank port 47 (or a second tank port 48), a first load pressure detection port 45 (or a second load pressure detection port 46). Oil supply device in which a check valve 105 is fitted in the oil passage.

[0018]

[Work]

 A part of the return oil flowing into one of the first and second actuator ports 34 and 35 is supplied to the other of the first and second actuator ports 34 and 35 from the check valve 105 and the oil passage 54. Part of the return oil can be supplied to the actuator.

[0019]

【Example】

 As shown in FIGS. 4 and 5, the second oil passage 54 that connects and disconnects the second load pressure detection port 46 formed on the main spool 49 and the second tank port 48 includes a small diameter shaft hole 100 and a large diameter shaft. The large-diameter shaft hole 101 is formed of a radial hole 102 that opens the hole 101 and the small-diameter shaft hole 100 on the outer peripheral surface of the main spool, and a radial hole 103 that opens the large-diameter shaft hole 101 on the outer peripheral surface of the main spool. A check valve 105 is provided to open to the second actuator port 35 at 104, and to block the flow of pressure oil from the large diameter shaft hole 101 to the small diameter shaft hole 100. An intermediate small-diameter portion 106 is formed on the main spool 49 so that the input port 44 communicates with one of the first or second load pressure detection ports 45 and 46. A communication hole 107 that connects the detection ports 45 and 46 is formed. The above configuration is schematically shown in FIG.

Next, the operation will be described. When the main spool 49 is slid to the right to the first pressure oil supply position B, the discharge pressure oil of the hydraulic pump 20 receives the input port 44, the intermediate small diameter portion 106, the second load pressure detection port 46, and the communication hole 107. , The first load pressure detection port 45, the first small diameter portion 50 and the first actuator port 34 are supplied to the actuator 88, and the return oil of the actuator 88 is the second actuator port 35, the radial hole 104, the large diameter axial hole 101, It flows out from the radial hole 103 to the second tank port 48. At this time, when the amount of return oil of the actuator 88 increases, a part of the return oil from the second actuator port 35 comes to the second side from the radial hole 104, the large diameter shaft hole 101, the check valve 105, the small diameter shaft hole 100, and the radial hole 102. It flows to the load pressure detection port 46 and is regenerated by the actuator 88.

[0021]

[Effect of device]

 Since a part of the return oil from the actuator 88 flows into the load pressure detection port side through the actuator port, the check valve 105 and the oil passage, a part of the return oil from the actuator 88 can be directly supplied to the actuator 88, and A large flow rate can be supplied to the actuator 88 without increasing the discharge flow rate of the pump 20.

[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 state where a main spool and a spool are incorporated in a valve block.

FIG. 4 is a cross-sectional view showing a state in which a main spool and a spool are incorporated in a valve block showing an embodiment of the present invention.

FIG. 5 is an enlarged view of an oil passage portion.

FIG. 6 is a hydraulic circuit diagram.

[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 ...
Pump port, 42 ... First port, 43 ... Second port,
44 ... Input 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, 105 ... check valve.

Claims (1)

[Scope of utility model registration request] 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 an input 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.
The main spool 49 for connecting / disconnecting the respective ports is fitted into 1 to form the directional control valve 22, and the first / second load pressure detecting ports 45, 46 are provided on the main spool 49 for the first / second tank ports 47, 48. First and second oil passages 53, 5 that connect and disconnect with
4, a pump port 39 opened in the check valve hole 37 and an oil passage 56 communicating the check valve hole 37 with the input port 44 are formed in the valve block 30, and the pump valve is provided in the check valve hole 37. The spool 60, which connects and shuts off the port 39 and the oil passage 56 and is stopped at the shut-off position, is used as the check valve portion 23, and the valve block 30 has a first opening for the pressure reducing valve hole 38.
The second 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 second port 43. And the spool 64 of the check valve portion 23 is pressed and held in the shut-off position to form a pressure reducing valve portion 24. The pressure reducing valve portion 24 and the check valve portion 24 are connected to each other. 23 as a pressure compensating valve 25, and the discharge path 2 of the hydraulic pump 20 is connected to the pump / first ports 39, 42.
1, the load pressure detection path 82 is connected to the second port 43, and the check valve 105 is connected to the first oil path 53 or the second oil path 54.
Via the first or second actuator port 34, 35
A pressure oil supply position that communicates with.