JPH0218801Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a hydraulic control circuit in which a hydraulic cylinder is driven by switching using a directional control valve to move a load up and down or reciprocate.

(Prior art) Conventionally, the hydraulic pressure control circuit for a hydraulic cylinder is
For example, the one shown in FIG. 7 is known.

In FIG. 7, 1 is a hydraulic cylinder that drives the load 2 up and down, 3 is a directional control valve, and 4 is a pilot check valve. When the directional control valve 3 is in the neutral position shown, the pump port P is connected to the load connection port A. , B are disconnected and communicated with the tank port T side, so the hydraulic cylinder 1 stops and locks the load 2. The drive to increase the load is performed by switching and moving the spool valve body 5 of the directional control valve 3 to the right.
With this switching, the pump port P communicates with the load connection port A, hydraulic pressure is supplied from port A to the pilot check valve 4, the poppet valve 6 is pushed up to open the valve, and the line fluid is supplied to the cylinder chamber 1a of the hydraulic cylinder 1. supply pressure. At the same time, since the load connection port B communicates with the tank port T, the liquid from the cylinder chamber 1b of the hydraulic cylinder 1 escapes to the tank, and the hydraulic cylinder 1 drives the load 2 upward.

On the other hand, for the downward drive of the load 2, when the spool valve body 5 of the directional control valve 3 is switched and moved to the left, the pump port P communicates with the load connection port B and flows into the cylinder chamber 1b, contrary to the upward drive. At the same time, the tank port T communicates with the load connection port A, and the line hydraulic pressure from the load connection port B is supplied as the pilot operating hydraulic pressure of the pilot check valve 4, so that the piston 7 is pushed up. The hydraulic cylinder 1 drives the load 2 downward by opening the poppet valve 6 and communicating the cylinder chamber 1a from the load connection port A to the tank port T via the pilot check valve 4.

(Problem to be solved by the invention) However, in such a conventional hydraulic control circuit, the load connection port A of the directional control valve 3 is in an open state communicating with the tank port T in the neutral position. , the pilot check valve 4 receives the pilot operating fluid pressure by downward switching to move the spool valve body 5 to the left side, and at the same time the pilot check valve 4 opens, and at the same time, the fluid in the cylinder chamber 1a flows to the tank side through between ports A and T. The problem was that the downward drive of the hydraulic cylinder 1 with the switching shock was initiated.

Therefore, as shown in FIG. 8, it is conceivable to use a directional control valve 3 having a structure in which the load connection port A and the tank port T are separated at the neutral position, but in this case, the spool valve body 5 When the pressure is switched downward to the left, ports P and B are first opened, line pressure is applied to the cylinder chamber 1b, and the hydraulic pressure in the cylinder chamber 1a increases by that amount. Then, while the line pressure is being applied to the cylinder chamber 1b, the pilot check valve 4 receives the pilot operation hydraulic pressure and opens, but at this time, the port A and T of the directional control valve 3 are not open. , cylinder chamber 1a
The hydraulic cylinder 1 is temporarily lowered due to the liquid compression caused by the increase in the hydraulic pressure. That is, in the case of Fig. 8, a shock-like downward start does not occur, but the hydraulic cylinder 1 causes a temporary downward movement immediately before the downward drive, and the amount of downward movement becomes more pronounced as the cylinder stroke becomes larger. However, there was a problem in that the start of the downward drive was intermittent, causing a shaky load movement.

In addition, since the port A and T of the directional control valve 3 are closed at the initial stage of switching when the pilot check valve 4 opens, there is a delay in the timing until the port A and T open, and there is a load on the line pressure at port A. There was an inconvenience that a large hydraulic pressure was added to the pressure due to the load of No. 2, and the pressure at port A became unnecessarily high.

(Means for Solving the Problems) The present invention has been made in view of the above-mentioned problems of the conventional technology, and is designed to provide a system that is linked to the switching of the main line by a directional control valve, and that also has an independent appropriate timing immediately before switching the main line. The object of the present invention is to provide a hydraulic pressure control circuit which reduces start shock when driving a load by supplying pilot operating hydraulic pressure to open a pilot check valve, and also ensures reliable stop locking of the load. , is configured as follows.

That is, as shown in FIG. 1A, the hydraulic cylinder 1 is reciprocated by switching the main line hydraulic pressure, and has three switching positions including a neutral position by switching the spool valve body 12, and the pump is turned off at the neutral position. Disconnect port P and tank port T from load connection port A, B and connect pump port P and tank port T to load connection port A with a straight or cross connection (see symbol in figure 2) in the remaining two switching positions. , B, and at least one hydraulic system that connects the load connection port A of the directional control valve 10 and the hydraulic cylinder 1 in a direction in which hydraulic pressure is supplied from the hydraulic cylinder 1 to close it. The directional control valve 10 also includes a pilot check valve 4, which is provided at A pilot operation port Pc is provided in communication with the pump port P for supplying pilot operation hydraulic pressure to the pilot check valve 4 to open it.

(Operation of the invention) The operation of the invention having such a configuration is, for example, when the spool valve element 12 of the directional control valve 10 is switched to the left.
2, the pump port P communicates with the pilot operation port Pc to supply pilot operation hydraulic pressure to the pilot check valve 4 and open it. At this time, the load connection ports A and B of the directional control valve 10 connect to the pump port P. and is in a state separated from tank port T. Further, as the spool valve body 12 moves, ports P-B and T-A communicate with each other, and as the throttle opening increases due to the movement of the spool valve body 12, liquid is gradually supplied to the hydraulic cylinder 1 and the hydraulic cylinder 1 The liquid is discharged from the tank and the load 2 starts to be smoothly lowered.

On the other hand, when the directional control valve 1 is returned to the neutral position in the middle of the downward drive, a braking action is obtained by restricting the opening between ports P-B and T-A due to the return of the spool valve body 12. When the gap between T and A is completely closed, the pilot operation port Pc is subsequently disconnected from the pump port P, the pilot check valve 4 is closed, and the cylinder chamber 1 of the hydraulic cylinder 1 is opened.
The a side has a pilot check valve 4 and a directional control valve 1.
Since it is double closed at 0 and kept in an airtight state,
Load stop locking is performed more reliably.

(Effects of the invention) The effects of the invention with such a configuration and operation are listed below.

First, a pilot operation port for opening and closing the pilot check valve is provided separately from switching the main line using the directional control valve, so the pilot check valve can be opened and closed independently of switching the main line. When driving a load, the pilot check valve is first opened, and then the throttle opening is increased by switching the main line, so that the load driving can be started smoothly, and the switching shock can be significantly reduced.

Also, when the load is stopped, the pilot check valve is kept open and the opening of the main line is reduced to brake the load, and finally the pilot check valve is closed to double close the main line on the tank side. However, the load can be more reliably locked.

(Embodiment) FIG. 1A is a hydraulic circuit diagram showing a cross-sectional structure of a pilot check valve and a directional control valve according to an embodiment of the present invention.

First, to explain the configuration, reference numeral 1 is a hydraulic cylinder for driving the load 2 up and down, and has cylinder chambers 1a and 1b partitioned by a piston.
drive up or down.

4 is a pilot check valve, which includes a hydraulic cylinder 1 and a directional control valve 10 which will be explained later.
It is provided on one side of the main line between the directional control valve 10 side, opens in response to line hydraulic pressure from the directional control valve 10 side, closes in response to line hydraulic pressure from the hydraulic cylinder 1 side, and regardless of the line hydraulic pressure. It has a check function that opens when supplied with pilot operating hydraulic pressure. The internal structure of the pilot check valve 4 includes a spring 13.
A poppet valve body 6 pressed by the main line is installed between ports C and D that connect the main line, a piston 7 is provided following the poppet valve body 6, and a liquid chamber 7a below the piston 7 is filled with pilot operating fluid. The other liquid chamber 7b communicates with a tank port F and is connected to the tank 14.

As is clear from the structure of the circuit check valve 4, when line hydraulic pressure is received from the port C side with no pilot operating hydraulic pressure applied, the check valve body 6 closes the internal passage, while the port D When line hydraulic pressure is applied from the side, the poppet valve body 6 is pushed up against the spring 13 to open the internal passage. Furthermore, even in the closed state when line hydraulic pressure is received from the port C side, the piston 7 pushes up the poppet valve body 6 by supplying pilot operating hydraulic pressure to the pilot port E, and forcibly closes the gap between ports C and D. open.

Next, the directional control valve 10 will be described. The directional control valve 10 includes a spool valve body 12 inside a valve body 11 that is switched and moved in the axial direction by a proportional electromagnetic solenoid or the like. , 16a, 16b, and 17, and an internal passage 18 is formed on the left side from the annular groove portion between the lands 16a and 16b, and is opened to the outer periphery of the land 15. Further, a groove 19 is formed in the axial direction of the outer periphery of the land 15 in which the internal passage 18 is opened. On the other hand, annular grooves 20, 21, 22, and 23 are formed from the left side on the inner circumferential surface of the shaft hole provided in the valve body 11 with which the spool valve element 12 slides.
A tank port T is provided in the annular groove 23 to connect the tank 14, and the tank port T is further communicated with the annular groove 21 on the left side via an internal passage 24. A pump port P that connects a hydraulic pressure source 25 is communicated with the annular groove 22, and a pilot operation port Pc that supplies pilot operation hydraulic pressure to the pilot check valve 4 is communicated with the annular groove 20 on the left side. At the neutral position, a groove 19 provided in the spool valve body 12 communicates the annular grooves 20 and 21, and communicates the pilot operation port Pc with the tank port T. Furthermore, load connection ports A, B are provided between the annular grooves 21 and 22 and between 22 and 23, respectively.

FIG. 1D shows the spool valve body 12 taken out, with a front view shown in a and a sectional view taken along line X-X in b.

The circuit connections of the hydraulic cylinder 1 and the pilot check valve 4 to the directional control valve 10 having such a structure include the load connection port A of the directional control valve 10.
is connected to the cylinder chamber 1a side of the hydraulic cylinder 1 via the pilot check valve, the load connection port B is connected to the cylinder chamber 1b side of the hydraulic cylinder 1, and the pilot operation port Pc is connected to the pilot check valve 4. Connected to pilot port E of

Next, the circuit operation of the embodiment shown in FIG. 1A will be explained.

First, when the directional control valve 10 is in the neutral position shown in FIG.
b and 17, and the pilot operation port Pc is in communication with the tank port T via the groove 19 and the internal passage 24. The received hydraulic pressure in the cylinder chamber 1a of the hydraulic cylinder 1 is sealed by closing the poppet valve body 6 of the pilot check valve 4.
By closing the load connection port A in the directional control valve 10, the load connection port A is sealed, and by doubly closing the line system on the cylinder chamber 1a side, the load 2 is reliably stopped and maintained.

Next, the hydraulic cylinder 1 drives the load 2 upward by switching the spool valve body 12 of the directional control valve 10 to the right as shown in FIG. 1B. When the spool valve body 12 starts moving to the right,
The spool valve body 12 is moved while the state in which the pilot operation port Pc is communicated with the tank port T by the groove 19 is maintained. When the land 16a enters the annular groove 22, line hydraulic pressure is supplied from the pilot port P to the load connection port A, and at the same time, the land 17 opens into the annular groove 23, so that the load connection port B is communicated with the tank port T. land 1
6a and the annular groove 22, and the land 17 and the annular groove 23
Line hydraulic pressure is supplied to the hydraulic cylinder 1 according to the throttle opening between, and the liquid discharged from the hydraulic cylinder 1 is returned to the tank 14.
At this time, since the pilot operating fluid pressure in the pilot operating port Pc is at the tank pressure, the spool valve body 6 in the pilot check valve 4 receives the line fluid pressure from the load connection port A and the spring 1
3, the hydraulic cylinder 1 gradually starts to drive the load 2 upward due to an increase in fluid volume according to the throttle opening at the upward switching position of the directional control valve 10, and the upward switching of the directional control valve 10 is performed. The load 2 shifts to an upward driving state at a speed corresponding to a predetermined flow rate determined by the position.

Next, the load 2 is driven downward by the hydraulic cylinder 1 by switching and moving the spool valve body 12 of the directional control valve 10, which is in the neutral position in FIG. 1A, to the left as shown in FIG. 1C. . When the spool valve body 12 is switched and moved to the left, the groove 19 first disengages from the annular groove 21 in the initial state of the switching movement, and the tank port T and the pilot operation port Pc
At the same time, the opening on the left side of the internal passage 18 opens into the annular groove 20, communicates the pump port P with the pilot operation port Pc, supplies pilot operation hydraulic pressure to the pilot check valve 4, and presses the piston 7 upward. Open the check valve body 6. At this time, load connection ports A and B are in a closed state.

Further, when the spool valve body 12 is moved to the left, the land 16b enters the annular groove 22, so that the pump port P communicates with the load connection port B, and line hydraulic pressure is supplied to the cylinder chamber 1b. enters the annular groove 21, the load connection port A communicates with the tank port T, and at this time, the pilot check valve 4 is open due to the supply of pilot operating hydraulic pressure, so the cylinder chamber 1a is connected via the pilot check valve 4. The tank port T of the directional control valve 10 is connected to the tank port T of the directional control valve 10, and the liquid can be discharged. Therefore, the hydraulic cylinder 1 includes the land 16b and the annular groove 22, and the land 15 and the annular groove 2 in the directional control valve 10.
The load 2 is gradually driven downward according to the supply of line liquid pressure according to each throttle opening of 1 and the discharge of liquid to the tank, and at a speed according to the throttle opening determined at the final switching position. Load 2 is now driven downward.

In this way, when the hydraulic cylinder 1 drives the load 2 upward, the pilot operation port of the directional control valve 10 is always communicated with the tank port, so the pilot check valve opens when line hydraulic pressure is supplied. Since the hydraulic cylinder is raised, supply of tank hydraulic pressure in the main line and communication with the tank port are performed at the same time, the hydraulic cylinder rises smoothly in response to an increase in the throttle opening of the main line in the directional control valve. Can be driven. In addition, when the directional control valve is returned to the neutral position, the load is stopped and maintained.
Since the pilot check valve is provided on the main line on the side where the hydraulic pressure increases due to the load, there is a double closure of the main line at the pilot check valve and the main line closure at the directional control valve. The load can be stopped and maintained reliably. Furthermore, when driving the load downward, at the initial stage of switching the directional control valve, pilot operation hydraulic pressure is first supplied to the pilot check valve to open it, and then line hydraulic pressure is supplied to one of the main lines and the other is opened. is communicated with the tank side to drive the load downward, and the start of the downward drive is carried out in response to an increase in the throttle opening of the main line in the directional control valve, making it possible to realize smooth downward drive of the load.

FIG. 2 is a hydraulic circuit diagram symbolizing the embodiment shown in FIG. 1. The hydraulic cylinder 1 and pilot check valve are the same as before, but the directional control valve 10 is in the neutral position where the main line is disconnected. In addition to the lowered position where the main line is cross-connected, a new pilot operation port Pc has been provided to connect the pilot operation port Pc to the tank port T at the neutral position.
At the initial stage of switching to the ascending switching position, the main line is disconnected and the pilot operation port is
It has a switching state in which Pc is communicated with the tank port T in the same way as in the neutral position, and also in a switching state in which the main line is stretched apart and the pump port P is communicated with the pilot operating port Pc in the switching stage of the downward switching position. There is.

FIG. 3A is a circuit diagram showing another embodiment of the present invention, in which a hydraulic cylinder 1 drives a load 2 in the horizontal direction, and pilot check valves are provided on both main lines. It is characterized in that the load is reliably stopped and locked.

That is, the direction control valve 10 is newly provided with an internal passage 18a that opens on the left side of the annular groove 20 following the internal passage 18 of the spool valve body 12 in the embodiment shown in FIG. In the initial stage when switching to either the left or right direction,
First, connect the pump port P to the pilot operation port Pc.
is connected to supply pilot operating hydraulic pressure. The main lines between the load connection ports A and B of the directional control valve 10 that connect the cylinder chambers 1a and 1b of the hydraulic cylinder 1 are provided with pilot check valves 4a and 4b, respectively. Pilot operation ports Pc of the directional control valve 10 are connected in parallel.

Note that the other configurations are the same as the embodiment shown in FIG. 1A.

Hydraulic cylinder 1 in this embodiment of FIG. 3A
When the spool valve body 12 of the directional control valve 10 is moved to the left as shown in Fig. 3C, the load 2 is driven to the left by supplying line hydraulic pressure to the cylinder chamber 1a of the hydraulic cylinder 1a. On the other hand, when the spool valve body 12 is switched to the right as shown in Fig. 3B, line hydraulic pressure is supplied to the cylinder chamber 1b of the hydraulic cylinder 1 to horizontally drive the load 2 to the right. Become. Directional control valve 10 for horizontally driving such a load 2 to the right or left
In the initial switching stage, the load connection brakes A and B are disconnected, and the internal passage 1 is first switched.
8 or 18a to the annular groove 19, the pilot operation port Pc is communicated with the pump port P, which is opened by supplying pilot operation hydraulic pressure to the pilot check valves 4a and 4b, and is opened by a subsequent cross connection or straight connection. By switching the line hydraulic pressure, the hydraulic cylinder 1 is horizontally driven in the left or right direction, and in this switching of the directional control valve, the drive of the hydraulic cylinder 1 is started by throttling and opening of the main line in the directional control valve 10. When the directional control valve 10 is returned to the neutral position, each of the main lines is doubly closed by the pilot check valves 4a, 4b and the directional control valve 10, so that the load The second stop lock can be performed more reliably.

FIG. 4 shows the embodiment of FIG. 3A in symbols, and the directional control valve 10 itself is the same as the symbol in FIG. ,4b
The difference is that .

FIG. 5A is a circuit explanatory diagram showing another embodiment for horizontally driving a load, and this embodiment is a pilot operation that independently supplies pilot operation hydraulic pressure to pilot check valves provided in each of the main lines. It is characterized by having separate ports.

That is, the directional control valve 10 basically has the same structure as the embodiment of FIG. Also internal passage 18
b, a groove 19b and an annular groove 20b are newly provided, and independent pilot operation ports Pc1 and Pc2 are provided for the annular grooves 20 and 20b, and pilot operation hydraulic pressure is supplied to the pilot check valves 4a and 4b, respectively. It is.

According to the embodiment of FIG. 5A, the sections 5B and 5C
At the left and right switching positions of the spool valve body 12 shown in the figure, when the directional control valve 10 is switched, pilot operating hydraulic pressure is supplied only to the pilot check valve installed in the main line communicating with the tank side to open it. Since the pilot check valve in the main line to which line hydraulic pressure is supplied opens even when pilot operating hydraulic pressure is not supplied, wasteful use of pilot operating hydraulic pressure can be avoided.

FIG. 6 is an explanatory circuit diagram showing another embodiment of the present invention. In this embodiment, when a load with high inertia is stopped by returning the directional control valve to the neutral position, the cylinder This feature prevents the pilot check valve from closing due to the hydraulic pressure on the side, and allows appropriate braking operation to be performed by restricting the opening of the directional control valve.

That is, the basic structure of the directional control valve 10 incorporates the structure of the embodiment shown in FIG. 3, and in the embodiment shown in FIG.
However, a new annular groove 26 is further provided on the left side of the annular groove 20, and the internal passage 18a is extended at the neutral position shown in the figure, and the annular groove 2 is opened as an internal passage 18d.
A check valve 30 that closes when the hydraulic pressure on the hydraulic cylinder 1 side becomes higher than the hydraulic pressure at the pump port P is provided in the internal passage 27 that opens at the annular groove 18d and connects the pump port P. It is characterized by what it did. The other configurations are the same as the embodiment shown in FIG.

The function of the check valve 30 in the directional control valve 10 shown in FIG. 6 is to return the directional control valve 10 to the neutral position while the hydraulic cylinder 1 is driving the load 2 by switching the spool valve body 12. If you try to stop the load, because it is a load with high inertia, for example, if you try to stop the load 2 while it is being driven in the left direction indicated by the arrow, the hydraulic cylinder 1
A considerably high hydraulic pressure is generated in the cylinder chamber 1a due to the inertia of the load 2, and is applied to the pilot check valve 4a which is opened due to the supply of pilot operating fluid. This high pressure from the cylinder side increases the pilot operating fluid pressure of the pilot check valve, causing the directional control valve 1
The hydraulic pressure at the pilot operation port Pc at 0 also increases, and the hydraulic pressure applied to the check valve 30 from the annular groove 26 becomes higher than the hydraulic pressure at the pump port P. In this case, if the check valve 30 is not provided, the liquid will be pushed back toward the pump port P side by the high pressure on the cylinder side, and the check valve 4a will be closed.
However, since the check valve 30 is provided in this embodiment, the check valve 30 closes in response to high pressure on the cylinder side, and even if high pressure is generated on the cylinder side due to the stoppage of a high inertia load, the pilot check valve will not close. Instead of closing, the main line can be stopped by a brake operation by narrowing the main line using the directional control valve 10.

[Brief explanation of the drawing]

Figures 1A, 1B, 1C, and 1D are circuit explanatory diagrams showing one embodiment of the present invention, Figure 2 is a circuit diagram showing the embodiment of Figure 1A with symbols, and Figures 3A, 3B, and 3
Figure C is a circuit explanatory diagram showing an embodiment for horizontal drive;
Fig. 4 is a circuit diagram showing Fig. 3A with symbols, Figs. 5A, 5B, 5C, and 6 are circuit explanatory diagrams showing other embodiments of horizontal drive, and Figs. 7 and 8 show conventional examples. It is a circuit explanatory diagram. 1: Hydraulic cylinder, 1a, 1b: cylinder chamber,
2: Load, 4, 4a, 4b: Pilot check valve, 6: Poppet valve element, 7: Piston, 10: Directional control, 11: Valve body, 12: Spool valve element, 13: Spring, 14: Tank, 15, 1
6a, 16b, 17: land, 18, 18a, 1
8b, 19d, 27: Internal passage, 20, 20b,
21, 22, 23: annular groove, 25: hydraulic pressure source, 3
0: Check valve, P: Pump port, T: Tank port, Pc: Pilot operation port, A, B:
Load connection port.

Claims (1)

[Claims for Utility Model Registration] (1) It has a hydraulic cylinder that is reciprocated by switching the hydraulic pressure of the main line, and has three switching positions including a neutral position by switching the spool valve body, and the pump port is in the neutral position. and a directional control valve that disconnects the tank port from the load connection port and alternately communicates the pump port and the tank port with the load connection port by straight connection or cross connection in the remaining two switching positions; and a load connection port of the directional control valve. and a pilot check valve, which is provided in at least one of the hydraulic systems connecting the hydraulic cylinders in a direction to be closed by the hydraulic pressure supplied from the hydraulic cylinder, and which opens in response to the supply of pilot operating hydraulic pressure, and further The directional control valve is a pilot check valve that, when the spool valve element is moved from a neutral position to at least one of the switching positions, supplies pilot operating hydraulic pressure to the pilot check valve to open it in the spool movement state immediately before the switching. A control circuit for a hydraulic cylinder characterized by having an operation port. (2) The directional control valve has a built-in check valve that closes in response to cylinder side hydraulic pressure in the middle of a passage communicating between the pump port and the pilot operation port. Hydraulic pressure control circuit as described in section.