JPH0550601B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field 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. This invention relates to a hydraulic circuit that reduces pipe resistance.

Conventional technology Conventionally, in variable regeneration circuit valves that regenerate and merge return oil from the rod-side oil chamber of a hydraulic cylinder into the head-side oil chamber, the return oil is blocked with a small-diameter spool to form a regeneration circuit. It was released when the pressure exceeded a certain value, and the regeneration release pressure was made variable based on signal pressure from the outside.

For example, FIG. 6 is a sectional view showing an example of a variable regeneration circuit valve. In this figure, the hydraulic cylinder 2 at the spool 55 of the variable regeneration circuit valve 53
A hollow hole is provided on the side that opens and closes the oil passage leading to the rod side oil chamber D, and a small diameter spool 62 having a center hole is fitted into the spool 62, which is biased by a spring 63 and has a center hole so as to be movable in the axial direction, and communicates with the hollow hole from the outer periphery. Notched holes 70, 68, and 71 are provided, and when the spool 55 is in neutral, the notched hole 70 communicates with the bridge passage 67 in the valve body 54, and the notched hole 68 is located between the bridge passage 67 and the high pressure passage 15'. Open,
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 communicate with the bridge passage 67, and at the same time, the piston oil is supplied through the oil passage 65. The notch hole 68 communicates with the chamber 59 and the high pressure passage 1.
5', and the notched hole 71 is located at a position that continues to communicate with the tank communication passage 16'. Further, a piston oil chamber 59 in which a piston 61 is inserted into the end and a small diameter spool oil chamber 69 are provided adjacent to the center hole of the small diameter spool 62 via a check valve 60, and the small diameter spool oil is inserted from the outer periphery. Notched holes 56 and 57 communicating with the chamber 69 are provided, and when the small diameter spool 62 is on the left side due to the urging force of the spring 63, the notched hole 56 communicates with the notched hole 68, and the notched hole 57
are closed by the inner wall of the spool 55, and when the small diameter spool 62 moves to the right against the biasing force of the spring 63, the notched holes 72 and 56 remain in communication with the notched holes 70 and 68, respectively. The notched hole 57 is provided at a position communicating with the notched hole 71 which communicates with the tank communication passage 16'.
Furthermore, a spring 63 is provided in the hollow hole of the spool 55 and biases the small diameter spool 62 between it and the spool 55, and this spring chamber forms an oil chamber 58 with the end face of the small diameter spool 62 and the plug 66. The oil chamber 58 is provided with a notched hole 25 through which an external pressure signal is introduced from the pilot oil port 52 when the spool 55 moves to the right.

In the variable regeneration circuit valve 53 having the above configuration, the spool 55 is switched to the right to extend the hydraulic cylinder 2, and when the load pressure is small, the return oil from the rod side oil chamber D is routed through the high pressure passage 15'.
A regeneration circuit is formed that passes through the notched holes 68 and 56, the small diameter spool oil chamber 69, the check valve 60, and the notched holes 72 and 70 and joins the bridge passage 67. Next, when the load pressure of the hydraulic cylinder 2 increases and the pressure of the head side oil chamber C and therefore the pressure of the bridge passage 67 rises, the pressure oil simultaneously flows into the piston oil chamber 59 through the oil passage 65. , the piston 61 tries to escape outward, and the reaction force is generated by the spring 63.
When the biasing force becomes larger than the biasing force of Therefore, the regeneration of the return oil in the rod side oil chamber D is canceled. Furthermore, when the signal pressure from the pilot oil port 52 passes through the notch hole 25 and reaches the oil chamber 58, a force proportional to that pressure acts on the small diameter spool 62 in addition to the biasing force of the spring 63. Since the rightward movement conditions are adjusted, the regeneration cancellation timing can be freely commanded depending on the magnitude of the signal pressure from the outside.

In addition, 6 and 6' in FIG. 6 are the spools 55.
7 and 7' are relief valves that regulate the maximum pressure in the high pressure passages 15 and 15', 16 and 16' are tank communication passages, and 39 is a pressure control valve during the switching transition period of the variable regeneration circuit valve 53. A load check valve that prevents oil from flowing backwards.
The structure is similar to that of a commonly used pilot-operated hydraulic switching valve. Also, 22 is the spool 55
It is an oil passage provided inside the small diameter spool 6.
The high pressure oil leaking from the outer circumference of 2 or from the piston oil chamber 59 is transferred to the tank communication passage 16 via the notch hole 23.
This prevents malfunctions caused by trapped pressure oil.

In addition, as another technique, a regenerative hydraulic system has been proposed as part of the conventional technique disclosed in Japanese Patent Application Laid-Open No. 59-23104, but in this technique,
For example, when a counter load occurs in that direction during the extension operation of a hydraulic cylinder, in order to prevent the pressure in the bottom side oil chamber, which is the operating side, from dropping abnormally and causing problems, the pressure is removed from the rod side oil chamber. The pressure difference between the throttle pressure while the return oil passes through the throttle oil passage provided in the hollow hole of the spool of the directional control valve and the pressure in the bottom side oil chamber is used to regenerate the oil inside the hollow hole of the spool. The structure is such that the spool forcibly moves, and when this squeezing pressure increases and the differential pressure increases, the port toward the spool's outer periphery, which is the path for return oil to return to the tank, is closed to achieve a regeneration effect. Therefore, all the regeneration functions of the regeneration hydraulic system of the disclosed technology are performed inside the spool of the hydraulic switching valve.

Problems to be Solved by the Invention Incidentally, in such conventional variable or normal regeneration circuit valves, all the devices that provide the regeneration function are housed within the spool of the valve, so the structure of the spool is Not only is it complicated, but if you try to minimize the passage resistance in the regeneration circuit, the regeneration circuit valve itself will have to be large, or the spool will have to be thin, which is not desirable from a strength standpoint. , the effective area of the passage cannot be secured, resulting in a limit to the amount of recycled oil.

Here, roughly dividing the functional configuration that should be provided in the variable regeneration circuit valve of FIG. Notched holes 68, 56 that serve as passageways for pressure oil to flow into the chamber C;
It has a small diameter spool oil chamber 69, a check valve 60, a notch hole 70, etc., and when the pressure in the head side oil chamber C is within a predetermined value, the return oil from the rod side oil chamber D is transferred to the head side oil chamber C. The second requirement for the regeneration function is to install a check valve 60 in the internal hollow hole of the small diameter spool 62 to prevent pressure oil from flowing from the head side oil chamber C circuit to the rod side oil chamber D circuit under any circumstances. The third requirement is that when the hydraulic cylinder 2 should exert its maximum capacity due to the load pressure of the head side oil chamber C, the rod side oil chamber D
The fourth requirement is to communicate the return oil from the pilot oil port 52 to the tank communication passage 51 through the notch hole 57 provided in the small diameter spool 62 and the notch hole 71 provided in the spool 55, and as a fourth requirement, to communicate the external pressure signal from the pilot oil port 52. , the spool 55, the small-diameter spool 62, and the plug 66 into the oil chamber 58, and adjusts the conditions under which the notch holes 57 and 71 communicate with each other depending on the magnitude of the pressure signal.

As mentioned above, the conventional variable regeneration circuit valve has a very complicated shape in order to provide the spool 55 with all of the above four functions, and also has a large cross-sectional area of the opening and closing part that serves as the pressure oil passage. The walls become thinner, the strength decreases, and the related parts built in become more complex. Here, the present invention includes:
Of the four functions mentioned above, the structure of the variable regeneration circuit valve is simplified by performing the first and second functions in an operating circuit other than the spool, and performing the third and fourth functions as they are in the regeneration circuit valve. An object of the present invention is to realize a regeneration hydraulic circuit that strengthens the spool strength and minimizes passage resistance of the regeneration pressure oil passage during regeneration.

Means for Solving the Problems This invention solves the above problems, and includes:
The contents will be explained below using FIG. 1 and FIG. 2 corresponding to the embodiment.

As shown in the hydraulic circuit diagram of FIG. 2, the hydraulic switching valve 3 is switched by the pressure signal of the pilot valve 29.
A switching valve 24 that normally closes the internal passage and opens the internal passage when a pressure signal is applied, and a check valve 10 built in the oil passage connected to the outlet port of the switching valve 24 in the direction of preventing backflow. The outlet side is connected to the head side oil chamber C of the hydraulic cylinder 2 by the oil passage 33.
A regeneration function valve 27 is provided with a joint port that communicates with the regeneration function valve 27, and a joint port that communicates the inflow side of the regeneration function valve 27 with the rod side oil chamber D of the hydraulic cylinder 2 through an oil passage 34 is provided. An oil passage 35 leading to one outlet port A of the switching valve 3 is located at an intermediate point of the oil passage 33, and an oil passage 36 leading to the other outlet port B is located at the intermediate point of the oil passage 33.
Although the oil passages 35 and 34 merge at the intermediate point of the oil passage 34, as shown in the figure, a joining port for the oil passages 35 and 34 may be provided so that the oil passages 35 and 34 merge inside the regeneration function valve 27. The spool switching pilot oil chamber of the switching valve 24 built into the regeneration circuit valve 27 includes a 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. Pilot oil path 3 branched from pilot oil path 30 to
Lead to 2.

As shown in FIG. 1, the hydraulic switching valve 3 has a hollow hole on the side of the spool 5 that opens and closes the oil passage leading to the rod-side oil chamber D of the hydraulic cylinder 2, and is biased by a spring 13 to move in the axial direction. A freely adjustable small diameter spool 12, which has a small diameter in the middle and forms a small diameter spool oil chamber 19 between the inner surface of the center hole of the spool 5, is inserted, and notched holes 18 and 21 are provided that communicate with the center hole from the outer periphery. 5 is neutral, the notched hole 18 opens between the bridge passage 17 and the high pressure passage 15' and is closed by the valve body 4, and the notched hole 21 communicates with the tank communication passage 16', and the spool 5 to the right, the notched hole 18 is in communication with the high pressure passage 15', and the notched hole 21 is in a position where it communicates with the tank communication passage 16'. Also, the small diameter spool 12 is connected to the spring 13.
As long as it is to the left due to the urging force of Then, the notched hole 21 is opened. Furthermore, the spool 5 incorporates a piston 11 that acts on the small diameter spool 12 in a direction against the biasing force of the spring 13, and a piston oil chamber 9, and the piston oil chamber 9 has a high pressure passage communicating with the A port. 15 to oil line 28
is understood.

The spring 13 is loosely inserted into the hollow hole of the spool 5 and biases the small diameter spool 12 against the spool 5, and this spring chamber forms an oil chamber 8 with the end face of the small diameter spool 12 and the plug 40. The oil chamber 8 is provided with a notched hole 25 that introduces an external pressure signal from the pilot oil port 14 when the spool 5 moves to the right. When in neutral or moving to the right, it is always connected to the tank communication passage 16, and the small diameter spool 12 and piston 11
It plays the role of returning drain leaking from the outer periphery to the tank.

Operation In Figures 1 and 2, pilot valve 2
Pull the operation lever 9 in the J direction to open the pilot oil passage 3.
When a signal pressure is generated at 0, the hydraulic switching valve 3 is switched to the G position, and at the same time, the switching valve 24 of the regeneration function valve 27 is also switched from the E position to the F position via the pilot oil passage 32. Therefore, the pressure oil supplied to the hydraulic 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, but when the load is small when the hydraulic cylinder 2 is extended, Its operating pressure is also 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 but closes the notch hole 21, so the return from the rod side oil chamber D The pressure of the oil increases, and the oil passes through the oil passage 34 and the F position passage of the switching valve 24, pushes open the check valve 10, and joins the oil passage 33, forming a regeneration circuit. Since the regeneration function valve can be provided independently of the valve 3, there are no restrictions on the cross-sectional area of the passage, the outer circumferential size, etc., and therefore the circuit resistance is minimized.

Next, the load on the hydraulic cylinder 2 increases, the pressure in the high pressure passage 15 rises, and the pressure oil flows into the piston oil chamber 9 through the oil passage 28, so that the acting force on the piston 11 becomes greater than the biasing force of the spring 13. Then, the small diameter spool 12 moves to the right inside the spool 5, opening the notched hole 21 which had been blocked, and as a result, the high pressure passage 15' opens the notched hole 18,
The small-diameter spool oil chamber 19 communicates with the tank communication passage 16' through the notch hole 21, so the return oil from the rod side oil chamber D flows through the oil passages 34, 36 and B of the hydraulic switching valve 3.
It is guided to the tank communication path through the port and regeneration is canceled.

Furthermore, when signal pressure is sent to the oil chamber 8 from the pilot oil port 14, a force proportional to that pressure is added to the biasing force of the spring 13, and the small diameter spool 12
Therefore, by making the release condition of the reproduction circuit variable, it is possible to obtain functions at exactly the same level as the conventional technology.

Example An embodiment of the present invention will be described below.

Fig. 1 is a longitudinal sectional view when the spool 5 of the hydraulic switching valve 3 used in the hydraulic circuit of the present invention is in the neutral position, Fig. 2 is a hydraulic circuit diagram showing the variable regeneration circuit of the present invention, and Fig. 3 is a hydraulic circuit diagram of the hydraulic switching valve 3 of the present invention. Fig. 4 shows the case when the spool 5 of the switching valve 3 is switched to the right and the load pressure of the A port is relatively low, and Fig. 4 shows the case when the load pressure of the A port increases from the same state as Fig. 3. 3 shows a vertical cross-sectional view of the hydraulic switching valve 3. In Fig. 2, 1 is a hydraulic pump that generates high-pressure oil for the operating circuit, and supplies the high-pressure oil to the hydraulic switching valve 3, and 2 is a hydraulic cylinder that has a head side oil chamber C and a rod side oil chamber D. The hydraulic pressure generated by the load applied to the rotor is mainly in the head side oil chamber C, and when the main purpose is to return after the operation is completed, the hydraulic pressure is generated in the rotor side oil chamber D.
Supply pressure oil to. 3 is a pilot pressure switching type hydraulic switching valve, and the A port of the hydraulic switching valve 3 is connected to the oil path 3.
5. Regeneration function valve 27, oil passage 33 to head side oil chamber C, and B port goes through oil passage 36, regeneration function valve 2.
7. It communicates with the rod side oil chamber D via an oil passage 34.

The regeneration function valve 27 has a switching valve 24 that opens an internal passage in response to a pressure signal from a pilot oil passage 32 and closes the internal passage when the pressure signal disappears, and oil passages 33 and 35 on the downstream side of the switching valve 24. It includes a check valve 10 that forms a free passage from the switching valve 24 toward the merging port, and the upstream oil passage is connected to the oil passage 36 leading to the B port of the hydraulic switching valve 3 and the hydraulic cylinder. It is provided with a joining port that joins the oil passage 34 leading to the rod side oil chamber D of No. 2. Reference numeral 29 denotes a pilot valve that generates a pressure signal to switch the hydraulic switching valve 3, and pilot oil passages 30 and 31 communicate with the pilot oil chambers 6 and 6' of the hydraulic switching valve 3, respectively, and simultaneously switch the hydraulic cylinder 2. The pilot oil passage 30 on the side to be expanded branches to become a pilot oil passage 32, which communicates with the pilot oil chamber of the switching valve 24. In addition, 4
Reference numeral 1 denotes a pilot pump that serves as a hydraulic pressure source for the pilot valve 29 and the like, and its discharge oil is connected to the pilot valve 29 and the like through an oil path 37. Also,
In FIG. 1 showing a longitudinal section of the hydraulic switching valve 3, reference numeral 4 is the valve main body, which is equipped with a spool 5 that moves left and right in response to a pressure signal acting on the pilot oil chamber 6 or 6'. A high pressure passage 15 communicating with the port B, a high pressure passage 15' communicating with the port B,
Tank communication passages 16, 1 which collect return oil from port A or B, relief oil from relief valves 7, 7', other drain oil, etc., and lead them to the tank.
6', the high pressure oil flowing from the hydraulic pump 1 through the load check valve 39 is passed through the high pressure passage 15 or 15'.
There is a bridge passage 17 for selectively supplying water to either one of the valves, and a spring center device attached to the valve body 4 that holds the spool 5 in a neutral position with a constant force. Although it is exactly the same as the known hydraulic switching valve, the hydraulic switching valve used in this variable regeneration circuit has a different built-in spool 5, and the valve body 4 has a pilot pressure introduced from the outside for commands to change the regeneration conditions. An additional mouth 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 contains therein a small diameter spool 12 and a piston 11 that are biased by a spring 13. When switched to , the bridge passage 17 and the high pressure passage 15 communicate with each other, but while the pressure in the high pressure passage 15 is low, that is, when the load when the hydraulic cylinder 2 is extended is relatively small, the high pressure passage 15' communicates with the low pressure passage. 16', on the other hand, 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 pushing force generated by the piston 11 is applied to the spring 13. When the biasing force 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' passes through the notch hole 18, the small diameter spool oil chamber 19, and the small diameter spool oil chamber 19.
It communicates with the tank communication passage 16' through the notched hole 21. The spring chamber housing the spring 13 also includes a small diameter spool 12,
The end face of the plug 40 and the inner circumferential surface of the hollow hole of the spool 5 form a closed oil chamber 8, and the freely setable command pressure sent from the oil passage 20 is sent to the pilot oil port 14 provided in the valve body 4. When the spool 5 moves to the right, it is guided to the oil chamber 8 through a notched hole 25 provided on the outer periphery of the spool 5. In addition, an oil passage 22 is provided in the solid shaft portion of the spool 5 opposite to the side where the hollow hole is provided, and the drain leaking from the outer periphery of the small diameter spool 12 and the piston 11 is routed through the notch hole 23 to the tank communication passage 16. It is designed to lead to Other than the above-mentioned shape, the oil passage formed by the narrow diameter portion of the spool 5 corresponding to the high pressure passage 15 and the tank communication passage 16, for example, is the same as that of a known hydraulic switching valve.

The operation of the variable regeneration circuit having the above hydraulic circuit configuration will be explained.

When the operating lever of the pilot valve 29 in FIG. 2 is tilted in the J direction, the pressure oil in the pilot pump 41 is regulated to the pilot pressure, passes through the pilot oil passage 30, and enters the pilot oil chamber of the hydraulic switching valve 3. The spool is switched to the G position, and at the same time the pilot pressure in the pilot oil passage 32 is changed to the regeneration function valve 27.
enters the pilot oil chamber of the switching valve 24 and switches the spool from the E position to the F position. In this state, the pressure oil of the hydraulic pump 1 flows through the G position passage of the hydraulic switching valve 3.
The oil flows into the head side oil chamber C of the hydraulic cylinder 2 through the oil passages 35 and 33, causing the cylinder 2 to extend, and the return oil in the rod side oil chamber D flows out into the oil passage 34, but when the hydraulic switching valve 3 position, and when the load resistance during extension of the hydraulic cylinder 2 is small, the pressure in the head side oil chamber C has not increased significantly, so the third
As shown in the figure, the notch hole 21 is connected to the small diameter spool 12.
Since it is closed at the outer periphery of the B port, there is a high pressure passage 15', a notch hole 18, and a small diameter spool oil chamber 1.
9, the oil passage leading to the 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 switching valve 24
Push open the check valve 10 through the F position passage,
The oil regenerates into the oil passage 33, flows into the head side oil chamber C, and accelerates the expansion speed of the hydraulic cylinder 2.

In the above state, when the load when the hydraulic cylinder 2 is extended increases, the operating pressure in the head side oil chamber C increases, and accordingly, the pressure in the high pressure passage 15 naturally increases, and as shown in Fig. 4, the high pressure oil , flows into the piston oil chamber 9 through the high pressure passage 15 and the oil passage 28, pushes the piston 11 and the small diameter spool 12 in contact with it to the right, and the operating force is applied to the spring 1.
If it becomes larger than the biasing force of 3, the small diameter spool 12
moves until the top touches the stopper 26,
As a result, the notched hole 21, which had been closed at the outer circumference of the small diameter spool 12, is opened, and the return oil from the oil passage 34 flows through the oil passage 36, the B port, the high pressure passage 15', the notched hole 18, the small diameter spool oil chamber 19, and the small diameter spool oil chamber 19. Notch hole 21
is opened to the tank via the tank communication passage 16', and the pressure in the oil passage 34 drops, so even if the switching valve 24 is switched to the F position, the confluence side of the oil passages 33 and 35 remains at high pressure. Therefore, the check valve 10 is not pushed open, and therefore the high pressure oil on the oil passage 33 side does not flow back through the check valve 10.
In addition, the conditions for canceling the playback function are as described above.
Piston 1 generated by pressure oil in head side oil chamber C
When the pushing force of the spring 13 becomes larger than the urging force of the spring 13, the external adjustable pilot pressure oil is applied to the pilot oil passage 20 and the pilot oil port 1.
4. When introduced into the oil chamber 8 through the notched hole 25, a force proportional to the pilot pressure is applied in the direction of the biasing force of the spring 13, counteracting the pushing force of the piston 11, so that the pilot pressure from the outside is The fact that it is possible to form a variable regeneration circuit that can freely select and determine the release timing of the regeneration function by adjusting and decreasing the pressure of pressurized oil is based on the structure and function of the variable regeneration circuit in the prior art. They are based on exactly the same idea.

Furthermore, 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 increases, 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 in the H position, and the hydraulic cylinder 2 performs a normal contraction operation.

FIG. 5 is a hydraulic/electrical circuit diagram showing a second embodiment of the present invention. In the first embodiment, the hydraulic switching valve 3 is switched by pilot pressure, whereas in the second embodiment, it is operated manually. That is, in FIG. 5, 3' is a manually operated hydraulic switching valve, 42 is its operating lever, and in conjunction with the operating lever 42, the hydraulic cylinder 2 is operated.
A limit switch 43 is provided that closes only when the operating lever 42 is operated in the direction of extending the regeneration function valve 27', and a solenoid switching valve 24' is built into the regeneration function valve 27'.
When the limit switch 43 is closed and an electric signal is sent through the electric wire 44, the electromagnetic switching valve 24' is energized and the internal passage is made to circuit. The same is true.

Effects of the Invention As explained above, in the circuit of the present invention, only the regeneration function part in the hydraulic regeneration circuit valve for hydraulic cylinder operation is provided independently from the hydraulic switching valve, so that it is compared to the spool of the conventional variable regeneration circuit valve. However, it is possible to use a hydraulic switching valve with a simple-shaped spool with few internal components, and a large cross-sectional area of the internal passage through which recycled oil passes, reducing fluid passage resistance. It is possible to maintain sufficient strength of the spool without increasing the shape of the spool. In addition, since an independent single regeneration function valve can be installed regardless of the installation position of the hydraulic switching valve, it is not only advantageous in terms of equipment and piping configuration, but also the regeneration function valve can be installed at a position immediately adjacent to the hydraulic cylinder. This makes the pressure oil path during regeneration the shortest, further reducing pressure loss in the piping.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view of the hydraulic switching valve used in the circuit of the present invention in a neutral state, Fig. 2 is a hydraulic circuit diagram of the invention, and Fig. 3 shows the spool of the hydraulic switching valve shown in Fig. 1 on the right side. Figure 4 is a vertical cross-sectional view when switching to
A longitudinal cross-sectional view when the small diameter spool moves to the right from the state shown in the figure, Fig. 5 is a hydraulic/electrical circuit diagram showing the second embodiment of the present invention, and Fig. 6 is a longitudinal cross-section of a conventional variable regeneration circuit valve. It is a diagram. 3...Hydraulic switching valve, 8...Oil chamber, 9...Piston oil chamber, 10...Check valve, 11...Piston, 12...Small diameter spool, 19...Small diameter spool oil chamber, 24...Switching valve , 27...Regeneration function valve.

Claims (1)

[Claims] 1 An operating system that expands and contracts the hydraulic cylinder by switching the hydraulic switching valve, and normally returns oil from the rod side oil chamber of the hydraulic cylinder to the tank communication path by the setting force of a spring built into the spool of the hydraulic switching valve. The oil passage is closed, but it is opened when the extension pressure of the hydraulic cylinder exceeds a predetermined value, and the setting force of the built-in spring is varied depending on the magnitude of signal pressure from the outside. In a hydraulic circuit configured with a switching valve, an internal oil passage is normally closed by the biasing force of a spring, but the switching valve opens in conjunction with an operating element in a direction to extend and operate a hydraulic cylinder;
There is a connection port for an oil path that leads from the downstream side to the head side oil chamber of the hydraulic cylinder, a check valve that forms a free oil path toward the connection port in the middle of the oil path, and a hydraulic A regeneration function valve consisting of a connection port of an oil passage leading to the rod side oil chamber of the cylinder is provided in the middle of the pipe line connecting the hydraulic switching valve and the head side oil chamber and the rod side oil chamber of the hydraulic cylinder. A variable regeneration circuit featuring: