JPH0738721Y2 - Cylinder control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a control device for controlling the lowering operation of, for example, a forklift.

(Prior Art) The conventional device shown in FIGS. 2 and 3 controls the lift cylinder S of a forklift, and connects the actuator passage 2 of the valve body 1 of the spool valve to the bottom side chamber 3 of the lift cylinder S. And the actuator passage 2
The operation check valve 8 is installed inside. By providing the operating check valve 8 in the actuator passage 2 as described above, the actuator passage 2 is provided with the operating check valve 8.
It is divided into 2a and cylinder side 2b.

Then, the pilot chamber 9 of the above-mentioned operation check valve 8
Communicate with a pilot port 14 via a pilot passage 13. A first flow passage 15 and a second flow passage 17 are formed in the spool 1a of the valve body 1, and the first flow passage 15 overlaps the pilot port 14 and the second flow passage is formed.
Reference numeral 17 has a relationship in which it overlaps with the return passage 7.

Further, the overlap amount is such that the overlap amount B of the second flow passage 17 is larger than the overlap amount A of the first flow passage 15 so that the second flow passage 17 is sufficiently larger than the first flow passage 15. It is formed so as to open in the return passage 7 after the delay.

The second flow path 17 is connected to the spool through the outflow hole 16.
It is configured such that it is always in communication with the annular groove 5 formed in 1a.

When the spool 1a is moved rightward from the neutral position in the figure, the supply passage 4 and the spool side 2a of the actuator passage 2 communicate with each other, so that the pressure fluid pushes open the poppet 8a of the operating check valve 8 to open the lift cylinder. The fork W is raised by communicating with the bottom side chamber 3 of S.

After that, if the spool 1a is returned to the neutral position shown in the drawing, the supply passage 4 is cut, so that the bottom side chamber 3 is closed by the poppet 8a of the operation check valve 8, and the pressure fluid is not supplied to the bottom side chamber 3 and the operation is performed. The check valve 8 remains closed. Therefore, the fork W is held at the desired position.

When the spool 1a is moved to the left in the drawing from the above state, the first flow path 15 is opened, and the fluid on the cylinder side 2b of the cylinder port 2 is orifice 12 → pilot chamber 9 → pilot passage 13 → pilot port 14 → First channel 15 → second
It flows into the return passage 7 via the annular groove 6.

Therefore, a differential pressure is generated before and after the orifice 12, and the pressure on the upstream side of the orifice 12 causes the poppet 8a to spring.
Move against 10 and open seat 11.

When the seat portion 11 is opened in this way, the fluid in the bottom side chamber 3 moves to the cylinder side 2b of the actuator passage 2 → the spool side.
2a → outlet hole 16 → outflow to the return passage 7 through the second flow path 17, and the fork W descends by its own weight.

(Problems to be Solved by the Present Invention) In the conventional device as described above, the first flow path of the spool 1a is used.
15. A and B overlap amounts are formed in the 15th and second flow paths 17, respectively, and there is a relation of A <B. However, if the overlap amount is excessive when the spool 1a is in the neutral position, The responsiveness of the cylinder control device deteriorates. Also,
When the overlap amount B is reduced, the overlap amount A is further reduced, the gap leakage of A is increased, the fluid pressure in the bottom side chamber 3 of the lift cylinder S is decreased, and the fork W cannot be held at a desired position. Is a problem.

The purpose of this idea is to have the spool in the neutral position,
Even if the overlap amount A is small, it is possible to prevent the gap A from leaking and hold the fork at a desired position.

(Means for Solving Problems) The present invention provides an actuator passage communicating with a cylinder and a supply passage to which a pressure fluid is supplied, in a valve main body provided with a slidable spool, and the actuator passage An operating check valve that allows only flow to the cylinder is provided in the passage process to divide the actuator passage into the spool side and the cylinder side, and the pilot chamber of this operating check valve is connected to the pilot port, while the spool has that An annular groove that allows the supply passage and the spool side of the actuator passage to communicate with each other or to block the communication depending on the moving position of the first flow path that overlaps with the pilot port when is in the neutral position. The one end side is always in communication with this annular groove, and the other end side has the spool in the neutral position. When the supply passage and the spool side of the actuator port are made to communicate with each other by forming the return passage and the second passage for keeping the overlap state, the overlap amount between the first passage and the pilot port and the second It is premised on a cylinder control device configured to increase the amount of overlap between the flow passage and the return passage.

This invention is based on the above-mentioned control device, and is provided with a first flow path, a communication hole, and an auxiliary outflow hole in the spool.
The flow passage communicates with the auxiliary outflow hole through the communication hole, and the opening end of the auxiliary outflow hole is configured to overlap the return passage when the spool is in the neutral position. The overlap amount between the flow passage and the pilot port and the overlap amount between the auxiliary outflow hole and the return passage are made substantially equal to each other, and the overlap amount between the second flow passage and the return passage is set between the first flow passage and the pilot port. It is characterized in that it is larger than the overlap and the amount of overlap between the auxiliary outflow hole and the return passage.

(Operation of the Invention) Since the invention is configured as described above, when the spool is in the neutral position, the effective wrap amount of the flow path formed in the spool communicating from the pilot chamber to the return passage is the first.
It is the sum of the amount of overlap between the flow passage and the pilot port and the amount of overlap between the auxiliary outflow hole and the return passage.
Therefore, the effective overlap amount becomes larger than the conventional amount by the overlap amount between the auxiliary outflow hole and the return passage.

(Effect of the present invention) According to the control device of the present invention, since the effective wrap amount when the spool is in the neutral position is large, the amount of fluid leakage in the pilot chamber is small, and the fork can be held at that position.

(Embodiment of the Present Invention) In the embodiment of the present invention shown in FIG. 1, an actuator check valve 8 is installed in the actuator passage 2, but the poppet 8a of the operator check valve 8 is attached to the pilot chamber 9
In addition, the poppet 8a is pressed against the seat portion 11 by the action of the spring 10 provided in the pilot chamber 9.

When the poppet 8a is in pressure contact with the seat portion 11 as described above, the inside of the actuator passage 2 is divided into the spool side 2a and the cylinder side 2b with the seat portion 11 as a boundary. An orifice 12 is formed in the poppet 8a, and the cylinder side 2b and the pilot chamber 9 are connected to each other.
It communicates via this orifice 12.

The pilot chamber 9 configured as described above has a pilot passage 13
The pilot port 14 is communicated with the pilot port 14, and the pilot port 14 is closed by the spool 1a when the spool 1a is held in the neutral position shown in the drawing.

The spool 1a has a first flow path 15, a communication hole 19 and an auxiliary outflow hole 18. Then, the first flow path 15
Is communicated with the auxiliary outflow hole 18 through the communication hole 19, and the opening end of the auxiliary outflow hole 18 overlaps the return passage 7 when the spool 1a is in the neutral position. . Then, the auxiliary outflow hole 18 and the return passage 7
The overlap amount a of the first flow path 15 and the pilot port 14 is the same as or almost the same as the overlap amount A.

Therefore, the effective overlap amount of the flow path formed in the spool communicating from the pilot chamber to the return passage is A + a, which is larger than the conventional amount by the overlap amount a.

The first flow path 15 thus configured opens to the pilot port 14 side when the spool 1a is moved leftward in the drawing.

An outflow hole 16 is formed in the first annular groove 5 of the spool 1a. Then, one end of the outflow hole 16 is always opened to the first annular groove 5, while the second flow passage 17 at the other end communicates with the return passage 7 when the spool 1a is moved to the left side as described above. I am doing it. The overlap amount B of the second flow path 17 is the overlap amount A of the first flow path 15.
It is formed to be larger, and the first flow path 17 opens in the return passage 7 sufficiently later than the first flow path 15.

Then, when the spool 1a is moved to the right in the drawing, the supply passage 4 and the spool side 2a of the actuator passage 2 communicate with each other, so that the pressure fluid pushes open the poppet 8a of the operation check valve 8 to open the bottom side chamber of the lift cylinder S. Communicate with 3 and raise the fork.

From this state, if the spool 1a is returned to the neutral position shown in the figure, the pressure check of the bottom side chamber 3 causes the operation check valve 8 to operate.
Since the poppet 8a is closed and the first flow path 15 on the right end of the spool is closed, the fork W can be held.

In the above state, however, the inlet of the first flow path 15 and the outlet of the auxiliary outflow hole 18 are closed in the flow path of the first flow path 15 → the communication hole 19 → the auxiliary outflow hole 18 formed in the spool 1a. Therefore, the amount of overlap between the spool 1a and its mounting hole in the above flow path system is the amount of overlap A between the first flow path and the pilot port, and the amount of overlap a between the auxiliary outflow hole and the return passage. Therefore, the above-mentioned overlap amount a is increased with respect to the overlap amount A of the first flow path 15 of the conventional device. Therefore, the amount of leakage from the gap on the outer circumference of the spool is reduced, and the load can be reliably maintained.

When the spool 1a is moved to the left in the drawing, the first flow path 15 is opened and the actuator passage 2 on the cylinder side.
The fluid of 2b is the orifice 12 → the pilot chamber 9 → the pilot passage 13 → the pilot port 14 → the first passage 15 → the communication hole 19
→ Flows to the return passage 7 via the auxiliary outflow hole 18.

Therefore, a pressure difference is generated before and after the orifice 12, and the pressure on the upstream side of the orifice 12 causes the poppet 8a to move against the spring 10 to open the seat portion 11.

When the seat portion 11 is opened in this way, the fluid in the bottom side chamber 3 moves to the cylinder side 2b of the actuator passage 2 → the spool side.
2a → outlet hole 16 → outflow to the return passage 7 through the second flow path 17, and the fork W descends by its own weight.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG.
FIG. 2 shows a conventional device, FIG. 2 is a sectional view, and FIG. 3 is a circuit diagram. S ... Lift cylinder, 1 ... Valve body, 1a ... Spool, 2 ...
Actuator passage, 4 ... Supply passage, 5 ... Annular groove, 7 ...
Return passage, 8 ... Operate check valve, 8a ... Poppet,
9 ... Pilot chamber, 14 ... Pilot port, 15 ... 1st flow path, 18 ... Auxiliary outflow hole, 19 ... Communication hole.

Claims (1)

[Scope of utility model registration request] Claim: What is claimed is: 1. A valve main body having a spool slidably provided with an actuator passage communicating with the cylinder and a supply passage to which a pressure fluid is supplied. An operating check valve that permits only the operation check valve is provided to divide the actuator passage into the spool side and the cylinder side, and the pilot chamber of this operating check valve communicates with the pilot port.On the other hand, the spool has a pilot chamber when it is in the neutral position. A first flow path in an overlapping state with the port,
An annular groove that connects or cuts off the communication between the supply passage and the spool side of the actuator passage according to the movement position, and one end that is always in communication with this annular groove, and the other end has a spool that is neutral. When in the position, forms a return passage and a second flow path that maintains an overlapping state,
A cylinder control device configured such that, when the supply passage and the spool side of the actuator port are communicated with each other, the overlap amount between the first flow passage and the pilot port and the overlap amount between the second flow passage and the return passage are increased. At
A first flow path, a communication hole, and an auxiliary outflow hole are formed in the spool, and the first flow path communicates with the auxiliary outflow hole through the communication hole, and the opening end of the auxiliary outflow hole has a spool. When it is in the neutral position, the return passage and the return passage are overlapped, while the overlap amount between the first flow passage and the pilot port and the overlap amount between the auxiliary outflow hole and the return passage are made substantially equal to each other. A cylinder control device in which the amount of overlap between the second flow passage and the return passage is larger than the amount of overlap between the first flow passage and the pilot port and the amount of overlap between the auxiliary outflow hole and the return passage.