JPH06117415A - Variable regeneration circuit - Google Patents

Abstract

PURPOSE:To simplify construction of a regeneration valve, which supplies pressure oil to the actuator of a hydraulic cylinder and the like and makes selective regeneration of the return oil, and to lessen passing resistance of a regeneration pressure oil passage while in process of regeneration and in operation. CONSTITUTION:A regeneration functional valve 27, which is provided with a directional control valve 24, which has its internal passage 34 usually closed and closes its internal oil passage by linking with a command signal operating an oil pressure switching valve 3 to the direction where pressure oil is supplied to a head side oil sac C of a hydraulic cylinder 2, in the midway of line pipes 35, 36 connecting the hydraulic directional control valve 3 and the hydraulic cylinder 2 together, a check valve 10, which forms a free passage only towards the line pipe 33 lead to a head side oil sac C of the hydraulic cylinder 2 from a delivery port of the directional control valve 24, and an inlet port lead to a line pipe 34 connecting a rod side oil sac D of the hydraulic cylinder 2 and the oil pressure switching valve 3 together, is provided independently of the oil pressure switching valve 3. Thus the construction of the valve itself can be simplified and the passing resistance of the regeneration oil pressure circuit in the course of regeneration can be kept to the least.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention simplifies the structure of a regeneration circuit valve that supplies pressure oil to an actuator such as a hydraulic cylinder, and selectively regenerates the return oil. The present invention relates to a hydraulic pressure regenerating circuit that reduces pipe resistance.

2. Description of the Related Art Conventionally, in the variable regenerative circuit valve that regenerates the return oil from the rod side oil chamber of the hydraulic cylinder into the head side oil chamber,
The return oil was blocked by a small-diameter spool to form a regeneration circuit, which was released when the operating pressure exceeded a certain value, and the regeneration release pressure was made variable by external signal pressure. For example, FIG. 6 is a sectional view showing an example of the variable regeneration circuit valve. In this figure, the rod side oil chamber D of the hydraulic cylinder 2 in the spool 55 of the variable regeneration circuit valve 53 is shown.
A hollow hole is provided on the side that opens and closes an oil passage that communicates with, and a small-diameter spool 62 that is urged by a spring 63 and has a central hole that is movable in the axial direction is inserted, and notch holes 70, 68 that communicate with the hollow hole from the outer periphery are provided. When the spool 55 is in the neutral position, the notch hole 70 communicates with the bridge passage 67 in the valve body 54, and the notch hole 68 forms the bridge passage 6.
7 and the high pressure passage 15 'are opened and closed by the valve body 54, the notch hole 71 communicates with the tank communication passage 16', and when the spool 55 is further moved to the right, the notch hole 70 continues to bridge. Communicating with the passage 67, and at the same time the oil passage 6
5, the notch hole 68 communicates with the piston oil chamber 59, the notch hole 68 communicates with the high pressure passage 15 ', and the notch hole 71 continues to communicate with the tank communication passage 16'. Also, the small spool 62
A piston oil chamber 59 having a piston 61 fitted at an end thereof and a small diameter spool oil chamber 69 are provided in the center hole of the small diameter spool oil chamber 6 adjacent to each other through a check valve 60.
9 are provided with notch holes 72, 56, 57, and when the small-diameter spool 62 is on the left side by the urging force of the spring 63, the notch hole 72 is formed by the notch hole 70 and the notch hole 56.
Communicates with the notch hole 68, and the notch hole 57 has the spool 55.
When the small-diameter spool 62 moves to the right against the biasing force of the spring 63, it is blocked by the inner wall of the notch hole 7.
Reference numerals 2 and 56 are provided in positions where they communicate with the notch holes 70 and 68, respectively, and the notch hole 57 communicates with the notch hole 71 that communicates with the tank communication passage 51. Further, the spring 63 is provided in the hollow hole of the spool 55,
The small-diameter spool 62 is biased between the spool 55 and the spring chamber. The spring chamber forms an oil chamber 58 by the end surface of the small-diameter spool 62 and the plug 66, and the spool 55 moves to the right in the oil chamber 58. Then, a notch hole 25 for introducing an external pressure signal from the pilot oil port 52 is provided. In the variable regeneration circuit valve 53 having the above-mentioned configuration, the spool 55 is switched to the right to extend the hydraulic cylinder 2, and when the load is small, the return oil from the rod side oil chamber D receives the high pressure passage 15 ′, the notch hole 68, 56, small diameter spool oil chamber 69,
A regeneration circuit is formed which joins the bridge passage 67 through the check valve 60 and the notch holes 72 and 70. Next, when the load on the hydraulic cylinder 2 increases and the pressure in the head-side oil chamber C, and thus the pressure in the bridge passage 67, rises, the pressure oil simultaneously flows into the piston oil chamber 59 through the oil passage 65.
When the piston 61 tries to slip out and its reaction force becomes larger than the biasing force of the spring 63, the small diameter spool 6
2 moves to the right inside the spool 55, the notched holes 71 and 57 that have been closed are opened, and the small diameter spool oil chamber 69 and the tank communication passage 16 ′ are in communication, so that the rod side oil chamber D The regeneration of return oil is canceled. Further, the signal pressure from the pilot oil port 52 passes through the notch hole 25 and the oil chamber 5
When reaching 8, the force proportional to the pressure is applied to the small diameter spool 6
In addition, since it acts in addition to the urging force of the spring 63 to adjust the rightward movement condition of the small diameter spool 62, the regeneration cancellation timing can be freely commanded according to the magnitude of the signal pressure from the outside. can do. 6, 6'is a pilot oil chamber for switching the spool 55, 7, 7'is a relief valve for regulating the maximum pressure of the high-pressure passages 15, 15 ', 16 and 16' are tank communication passages, 39
Is a load check valve for preventing pressure oil from flowing back during the transitional period of switching of the variable regeneration circuit valve 53, and has the same structure as a commonly used pilot operated hydraulic switching valve. Further, 22 is an oil passage provided inside the spool 55, and the high pressure oil leaked from the outer circumference of the small diameter spool 62 or the piston oil chamber 59 is caused to flow out to the tank communication passage 16 via the notch hole 23 and is closed. It is designed to prevent malfunction due to pressure oil.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in such a conventional variable regenerative circuit valve, the structure of the spool is complicated because all the devices for imparting the regenerating function are housed in the spool of the valve. Not only that, when trying to minimize the passage resistance in the regeneration circuit, the regeneration circuit valve itself becomes large, or the thickness of the spool is reduced, which is not preferable from the viewpoint of strength and the passage. The effective area cannot be secured, and the amount of reclaimed oil is limited. Here, roughly dividing the functional configuration to be provided in the variable regeneration circuit valve of FIG. 6 which is an embodiment according to the prior art, the first requirement is that during regeneration, from the rod side oil chamber D of the hydraulic cylinder 2 to the head side oil. It has notch holes 68, 56, which are passages through which pressure oil flows into the chamber C, a small-diameter spool oil chamber 69, a check valve 60, a notch hole 70, and the like. The function of regenerating the return oil from the side oil chamber D into the head side oil chamber C, and the second requirement is that the head side oil is generated when the pressure in the head side oil chamber C becomes higher than that in the rod side oil chamber D. Room C
The check valve 60 for preventing the pressure oil from flowing into the circuit of the rod side oil chamber from the circuit of No. 2 is provided in the inner hollow hole of the small diameter spool 62. The third requirement is that the pressure of the head side oil chamber C is further increased. When the hydraulic cylinder 2 is to be raised and exerts its maximum capacity, the return oil from the rod side oil chamber D is passed through the notch hole 57 provided in the small diameter spool 62 and the notch hole 71 provided in the spool 55 to the tank communication passage 16 ′, And the fourth requirement is that an external pressure signal is introduced from the pilot oil port 52 to the oil chamber 58 formed by the spool 55, the small-diameter spool 62, and the plug 66, and the notch hole depends on the magnitude of the pressure signal. This is a function of adjusting the conditions under which 57 and 71 communicate with each other. As described above, the conventional variable regeneration circuit valve has a very complicated shape because the spool 55 is provided with all of the above four functions, and the opening / closing cross section of the pressure oil passage is increased. It becomes thinner and the strength is reduced, and the related parts to be built in are complicated. Here, the present invention provides, among the four functions described above,
By performing the first and second functions in the operating circuit other than the spool and performing the third and fourth functions as they are in the regeneration circuit valve, the structure of the variable regeneration circuit valve is simplified and the spool strength is enhanced. At the same time, it is intended to realize a regeneration hydraulic circuit that minimizes the passage resistance of the regeneration pressure oil passage during regeneration.

Means for Solving the Problems This invention solves the above problems, and the contents thereof will be described below with reference to FIGS. 1 and 2 corresponding to the embodiments. As shown in the hydraulic circuit diagram of FIG. 2, the hydraulic switching valve 3 that is switched by the pressure signal of the pilot valve 24 and the switching valve 24 that normally closes the internal passage and opens the internal passage when a pressure signal is applied, and the switching valve. A check valve 10 is built in the oil passage connected to the outlet port of the valve 24 in a direction to prevent the inflow, and the outlet port is connected to the head side oil chamber C of the hydraulic cylinder 2 by the oil passage 33. 27, the inflow side port of the regeneration function valve 27 and the rod side oil chamber D of the hydraulic cylinder 2 are connected by an oil passage 34, and further connected to one outlet port A of the hydraulic pressure switching valve 3 with an oil passage 35. Is at the midpoint of the oil passage 33 and the other outlet port B
The oil passage 36 leading to the is joined to the intermediate point of the oil passage 34,
In the spool switching pilot oil chamber of the switching valve 24 built in the regeneration circuit valve 27, the pilot oil chamber for switching the spool of the hydraulic switching valve 3 to the side that supplies pressure oil to the head side oil chamber C of the hydraulic cylinder 2. A pilot oil passage 32 branched from the pilot oil passage 30 is introduced. Also, the hydraulic pressure switching valve 3
As shown in FIG. 1, a hollow hole is provided on the side of the spool 5 that opens and closes an oil passage communicating with the rod-side oil chamber D of the hydraulic cylinder 2 and is urged by a spring 13 to move in the axial direction. The small diameter spool 12 that forms a small diameter spool oil chamber 19 with the inner surface of the center hole of the spool 5.
Notch holes 18 and 21 that are inserted from the outer circumference to the center hole
When the spool 5 is in the neutral position, the notch hole 18 is opened in the middle of the bridge passage 17 and the high pressure passage 15 'and is closed by the valve body 4, and the notch hole 21 communicates with the tank communication passage 16'2. When the spool 5 is moved rightward, the notch hole 18 communicates with the high pressure passage 15 ', and the notch hole 21 continues to communicate with the tank communication passage 16'. As long as the small-diameter spool 12 is on the left side by the biasing force of the spring 13, the notch hole 21 is closed on the outer periphery of the large-diameter portion on the right end of the small-diameter spool shown in FIG.
The notch hole 21 is opened when it moves to the right until it contacts the stopper 26 against the biasing force of No. 3. Further, the spool 5 includes a small-diameter spool 12 and a spring 13
The piston 11 and the piston oil chamber 9 which act in the direction against the urging force of the piston 11 and the piston oil chamber 9 are built in, and an oil passage 28 is communicated from the high pressure passage 15 communicating with the A port to the piston oil chamber 9. The spring 13 is loosely inserted in the hollow hole of the spool 5 to bias the small-diameter spool 12 against the spool 5, and the spring chamber forms an oil chamber 8 by the end surface of the small-diameter spool 12 and the plug 40. The oil chamber 8
When the spool 5 moves to the right, the pilot oil port 14
Is provided with a notch hole 5 for introducing an external pressure signal from the tank, and the oil passage 22 is always provided with the notch hole 23 when the spool 5 is moving to the neutral and rightward.
6 and plays a role of returning drain leaking from the outer circumference of the small diameter spool 12 and the piston 11 to the tank.

Operation In FIGS. 1 and 2, when the operating lever of the pilot valve 29 is pulled in the J direction and a signal pressure is generated in the pilot oil passage 30, the hydraulic switching valve 3 is switched to the G position, and at the same time the pilot oil passage 32 Through the switching valve 24 of the regeneration function valve 27
Is also switched from the E position to the F position. Therefore, the pressure oil supplied to the hydraulic pressure switching valve 3 flows into the head side oil chamber C of the hydraulic cylinder 2 through the A port and the oil passages 35 and 33. The operating pressure is low, the force acting on the piston 11 is smaller than the biasing force of the spring 13, and the small diameter spool 12 does not move to the right and closes the notch hole 21, so that the return oil from the rod side oil chamber D The pressure rises, and the F of the oil passage 34 and the switching valve 24
Pass the position passage and push open the check valve 10 to open the oil passage 33.
Form a reproducing circuit that merges with. When the load of the hydraulic cylinder 2 increases and the pressure of the high pressure passage 15 rises, the pressure oil flows into the piston oil chamber 9 through the oil passage 28 and the acting force of the piston 11 becomes larger than the urging force of the spring 13. ,
The small-diameter spool 12 moves to the right inside the piston 5 to open the notch hole 21 that has been closed,
The high pressure passage 15 'has a notch hole 18 and a small diameter spool oil chamber 1
9. Since the notch hole 21 communicates with the tank communication passage 16 ', the return oil from the rod side oil chamber D is guided to the tank communication passage through the oil passages 34 and 36 and the B port of the hydraulic pressure switching valve 3, and the regeneration is canceled. It Further, when the signal pressure is sent from the pilot oil port 14 to the oil chamber 8, a force proportional to the pressure acts on the small-diameter spool 12 in addition to the urging force of the spring 13, so that the release condition of the regeneration circuit can be changed. can do.

Example An example of the present invention will be described below. FIG. 1 is a vertical cross-sectional view when a spool 5 of a hydraulic pressure switching valve 3 used in the hydraulic circuit of the present invention is in a neutral position, FIG. 2 is a hydraulic circuit diagram showing a variable regeneration circuit of the present invention, and FIG. Spool 5 of switching valve 3
Is switched to the right when the load pressure of the A port is relatively low, and in FIG. 4, when the load pressure of the A port increases from the state similar to that of FIG. 3, the longitudinal switching of the hydraulic switching valve 3 for each is performed. The side view is shown. In FIG. 2, 1 is a hydraulic pump for generating high-pressure oil in the operating circuit, which supplies the high-pressure oil to the hydraulic switching valve 3, and 2 is a hydraulic cylinder having a head-side oil chamber C and a rod-side oil chamber D. The hydraulic pressure generated by the load applied to the head-side oil chamber C is mainly supplied to the rod-side oil chamber D when the operation is completed mainly after returning from the operation. 3 is a pilot pressure switching type hydraulic switching valve,
The A port of the hydraulic pressure switching valve 3 has an oil passage 35 and a regeneration function valve 2
7 through the oil passage 33 to the head side oil chamber C, and the B port communicates with the rod side oil chamber D through the oil passage 36, the regeneration function valve 27 and the oil passage 34. The remain function valve 27 opens the internal passage by the pressure signal of the pilot oil passage 32 and closes the internal passage when the pressure signal disappears, and the oil passage 33 is connected to the downstream side of the switching valve 24. The check valve 10 that forms a free oil passage in the port direction is built in, and the upstream oil passage communicates with the joint port with the oil passage 36 that communicates with the B port of the hydraulic switching valve 3 and the rod side oil chamber D of the hydraulic cylinder 2. Oil passage 3
4, and the internal oil passage extending from the check valve 10 to the joint port with the oil passage 33 is branched and communicates with the joint port with the oil passage 35. Reference numeral 29 is a pilot valve for generating a pressure signal for switching the hydraulic pressure switching valve 3, and the pilot oil passages 30 and 31 are respectively in communication with the pilot oil chambers 6 and 6'of the hydraulic pressure switching valve 3, and at the same time, the hydraulic cylinder 2 is connected. The pilot oil passage 30 on the extending side is branched into a pilot oil passage 32, which communicates with the pilot oil chamber of the switching valve 24. 41 is a pilot valve 29
Is a pilot pump that serves as a hydraulic pressure source, and its discharge oil is connected to a pilot valve 29 and the like by an oil passage 37. Further, in the hydraulic switching valve 3 shown in FIG. 1 showing its longitudinal section, 4 is its valve body, which is internally provided with a spool 5 which moves left and right according to a pressure signal acting on a pilot oil chamber 6 or 6 ', The high-pressure passage 15 communicating with A, the high-pressure passage 15 'communicating with port B, the return oil from the port A or B, the relief oil of the relief valves 7 and 7', and other drain oil are also collected and guided to the tank. The high pressure oil flowing from the tank communication passages 16 and 16 'and the hydraulic pump 1 via the load check valve 39 is supplied to the high pressure passage 15 or 15
There is a bridge passage 17 for selectively supplying to any one of ‘′, and a spring center device attached to the valve body 4 for holding the spool 5 in a neutral position with a constant forcing force. Although it is exactly the same as the known hydraulic switching valve, the hydraulic switching valve used in the present hydraulic regeneration circuit has a different spool 5 installed therein, and the valve body 4 has a command pilot pressure for changing the regeneration condition from the outside. An additional inlet is provided. That is, as described in detail in the previous section, the switching spool 5 has a hollow hole on the B port side, and internally has a small diameter spool 12 and a piston 11 biased by a spring 13, and the spool 5 is located on the right side. When the pressure in the high pressure passage 15 is low, that is, when the load when the hydraulic cylinder 2 extends is relatively small, the high pressure passage 15 ′ is changed to the low pressure passage 16 ′. However, the pressure in the high-pressure passage 15 rises, a part of the pressure oil flows into the piston oil chamber 9 through the oil passage 28, and the pressing force generated by the piston 11 is the urging force of the spring 13. When the small-diameter spool 12 is overcome, the small-diameter spool 12 moves to the right in the hollow hole of the spool 5 until it comes into contact with the stopper 26, and the high-pressure passage 15 'is passed through the notch hole 18, the small-diameter spool oil chamber 19, and the notch hole 21. Click communication passage 16 'it is so as to communicate with the. Further, the spring chamber accommodating the spring 13 includes a small diameter spool 12 and a plug 40.
And the inner peripheral surface of the hollow hole of the spool 5 form an oil chamber 8 in a closed chamber, and the freely settable command pressure sent from the oil passage 20 is the pilot oil port 14 provided in the valve body 4 and the oil passage. Therefore, when the spool 5 moves to the right, the spool 5 is guided to the oil chamber 8 through the notch hole 25 provided in the outer periphery of the spool 5. An oil passage 22 is provided in the body shaft portion opposite to the side where the hollow hole of the spool 5 is provided, and drain leaking from the outer circumference of the small diameter spool 12 and the piston 11 is passed through the notch hole 23 to the tank communication passage 16 It is supposed to lead to. Other than the above shape, for example, the oil passage formed by the small diameter portion of the spool 5 corresponding to the high pressure passage 15 and the tank communication passage 16 is the same as a known hydraulic switching valve. The operation of the variable regeneration circuit having the above hydraulic circuit configuration will be described. When the operating lever of the pilot valve 29 in FIG. 2 is tilted in the J direction, the pressure oil of the pilot pump 41 is adjusted to the pilot pressure, and the pilot oil passage 30
Through the pilot oil chamber of the hydraulic switching valve 3 to switch the spool to the G position. At the same time, the pilot pressure in the pilot oil passage 32 enters the pilot oil chamber of the switching valve 24 of the regeneration function valve 27 to shift the spool from the E position to the F position. Switch to. In this state, the pressure oil of the hydraulic pump 1 flows into the head-side oil chamber C of the hydraulic cylinder 2 through the G position passage of the hydraulic switching valve 3 and the oil passages 35 and 33, and the cylinder 2 is extended to extend the rod-side oil. The return oil in the chamber D flows out to the oil passage 34, but the hydraulic pressure switching valve 3 is set to G
At the position, and when the load resistance when the hydraulic cylinder 2 is extended is small, the pressure in the head side oil chamber C does not rise so much either. Therefore, as shown in FIG. Since it is closed at the section, from the B port to the high pressure passage 15 ', the notch hole 18, the small diameter spool oil chamber 1
The oil passage leading to the 9 notch hole 21 and the tank communication passage 16 ′ is blocked, so that the return oil from the oil passage 34 does not flow into the oil passage 36, and the check valve passes through the F position passage of the switching valve 24. 10 is pushed open, regenerated and merged into the oil passage 33 and flows into the head side oil chamber C, and the extension speed of the hydraulic cylinder 2 is accelerated. From the above state, when the load at the time of extension of the hydraulic cylinder 2 increases, the operating pressure of the head side oil chamber C rises, the pressure of the high pressure passage 15 naturally increases accordingly, and as shown in FIG. , The high-pressure passage 15 and the oil passage 28 to flow into the piston oil chamber 9, push the piston 11 and the small-diameter spool 12 in contact with the piston to the right, and when the operating force becomes larger than the biasing force of the spring 13, the small-diameter spool. 12
Moves until the top comes into contact with the stopper 26, and as a result, the notch hole 21 that has been closed at the outer peripheral portion of the small diameter spool 12 opens, and the return oil from the oil passage 34 receives the oil passage 36, the B port, and the high pressure passage. 15 ', the notch hole 18, the small-diameter spool oil chamber 19, the notch hole 21, and the tank communication passage 16' to open to the tank, and the pressure in the oil passage 34 drops, so that the switching valve 24 is switched to the F position. Since the oil passage 33 side has a high pressure, the check valve 10 is not pushed open, and the high pressure oil on the oil passage 33 side does not flow back by the check valve 10. As described above, the condition for canceling the regeneration function is when the pressing force of the piston 11 generated by the pressure oil in the head side oil chamber C becomes larger than the biasing force of the spring 13 or an external adjustment is possible. Use pilot pressure oil as pilot oil passage 20, pilot oil port 14, notch hole 25
When the oil is introduced into the oil chamber 8 via, the force proportional to the pilot pressure is added in the direction of the urging force of the spring 13 and opposes the pushing force of the piston 11. It is possible to form a variable reproduction circuit which can freely select and determine the release time of the reproduction function by adjusting and supplying. When the operating lever of the pilot valve 29 is tilted in the I direction, only the pilot pressure in the pilot oil passage 31 rises, so the switching valve 24 returns to the E position, and the passage between the oil passage 34 and the check valve 10 is closed. On the other hand, the hydraulic switching valve 3 is switched to the H position, and the hydraulic cylinder 2 is normally reduced. FIG. 5 is a hydraulic / electrical circuit diagram showing a second embodiment of the present invention. In the first embodiment, the hydraulic pressure switching valve 3 is switched by pilot pressure, whereas in the second embodiment,
Regarding the manual case. That is, 3'in FIG.
Is a manually operated hydraulic switching valve, 42 is an operating lever thereof, and a limit switch 43 is provided which closes only when the operating lever 42 is operated in the direction of extending the hydraulic silling 2 in conjunction with the operating lever 42. An electromagnetic switching valve 24 'is built in the regeneration function valve 27' so that when the limit switch 43 is closed and an electric signal is sent through the electric wire 44, the electromagnetic switching valve 24 'is excited to open the internal passage. Other than that, the configuration is the same as that of the first embodiment, and the operation is also the same.

Effects of the Invention As described above, in the circuit of the present invention, since only the regeneration function section of the hydraulic regeneration circuit valve for operating the hydraulic cylinder is provided independently of the hydraulic switching valve, the spool of the conventional variable regeneration circuit valve is provided. In comparison with the above, it is possible to use a hydraulic switching valve equipped with a spool having a simple shape. Therefore, it is possible to increase the internal passage cross-sectional area, reduce fluid passage resistance, and maintain sufficient spool strength. it can. Further, since an independent single regeneration function valve can be provided regardless of the installation position of the hydraulic pressure switching valve, it is not only advantageous in the configuration of equipment and piping, but also the regeneration function valve is provided in a position near the hydraulic cylinder. As a result, the pressure oil path during regeneration will be the shortest and the pressure loss in the piping will be small.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a hydraulic switching valve used in the circuit of the present invention in a neutral state, and FIG. 2 is a hydraulic circuit diagram of the present invention.
FIG. 3 is a vertical sectional view when the hydraulic switching valve shown in FIG. 1 is switched to the right in the drawing, and FIG. 4 is a vertical sectional view when the small diameter spool is moved to the right from the state of FIG. 5 is a hydraulic / electrical circuit diagram showing a second embodiment of the present invention, and FIG. 6 is a longitudinal sectional view of a conventional variable regeneration circuit valve. 3. ． ． ． ． ． ． ． Hydraulic pressure switching valve 8. ． ． ． ． ． ． ． Oil chamber 9. ． ． ． ． ． ． ． Piston oil chamber 10. ． ． ． ． ． ． ． Check valve 11. ． ． ． ． ． ． ． Piston 12. ． ． ． ． ． ． ． Small diameter spool 19. ． ． ． ． ． ． ． Small spool oil chamber 24. ． ． ． ． ． ． ． Switching valve 27. ． ． ． ． ． ． ． Regeneration function valve

Claims (1)

[Claims] In an operating system for expanding and contracting a hydraulic cylinder by switching a hydraulic switching valve, the hydraulic switching is performed in a direction in which pressure oil is supplied to a head-side oil chamber of the hydraulic cylinder in the middle of a pipeline connecting the hydraulic switching valve and the hydraulic cylinder. A switching valve in which the internal oil passage is opened in synchronization with a command signal for operating the valve and the internal passage is normally closed, and a pipe communicating from the outlet port of the switching valve to the head-side oil chamber of the hydraulic cylinder. A regenerative function valve provided with a check valve forming a free passage only toward the passage and an inlet port communicating with a pipe connecting the rod-side oil chamber of the hydraulic cylinder and the hydraulic switching valve. Variable playback circuit.