JPH0645682Y2 - 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 FIG. 2 controls a cylinder S of a forklift, and connects a cylinder port 2 of a spool valve 1 to a bottom side chamber 3 of the cylinder S and connects them between them. Is provided with a check valve 4 and a flow regulator valve 7 in parallel. The check valve 4 allows only the flow from the cylinder port 2 to the bottom side chamber 3 of the cylinder S.

Then, when the spool 1a of the spool valve 1 is moved rightward from the neutral position in the drawing, the supply passage 8 and the cylinder port 2 communicate with each other via the first annular groove 9 formed in the spool 1a.

Therefore, the pressure fluid supplied from the pump port 10 flows through the flow passage 11 → the supply passage 8 → the annular groove 9 → the cylinder port 2
→ Supplied to the bottom chamber 3 of the cylinder S via the check valve 4 and the fork W is raised.

After that, when the spool 1a is returned to the neutral position shown in the drawing, the supply passage 8 is cut off, so that the pressure fluid is discharged from the bottom side chamber 3
And the check valve 4 remains closed. Therefore, the fork W is held at the desired position.

When the spool 1a is moved leftward in the drawing from the above state, the return passage 13 communicates with the cylinder port 2 via the first annular groove 9, so that the bottom side chamber 3 of the cylinder S moves from the flow regulator valve 7 to the cylinder port. 2 → Communicating with the return passage 13 through the first annular groove 9, the fork W descends by its own weight.

The lowering speed of the fork W by this cylinder control device is
It is controlled by the outflow amount of fluid in the cylinder. And
This outflow amount is controlled by the opening degree of the flow regulator valve 7 and the flow path opening degree formed when the first annular groove 9 faces the return passage 13. However, since the opening degree of the flow regulator valve 7 is constant, the lowering speed of the fork W is substantially controlled by the stroke setting by the manual operation of the spool 1a.

(Problems to be Solved by the Present Invention) In the conventional control device as described above, even if the switching stroke of the spool 1a is constant, the descending speed of the fork W changes depending on the load of the fork W. For example,
Even if the switching stroke of the spool 1a is constant, the lower the load, the faster the lowering speed. On the contrary, the lower the load, the slower the descending speed. For this reason, the operator must control the switching stroke of the spool 1a while sensuously determining the actual load lowering speed, but this operation requires considerable skill.

Further, when the stroke of the spool 1a is suddenly operated beyond a predetermined stroke, the fork W suddenly descends to cause a jumping phenomenon.

Further, there is a problem that a space for providing the flow regulator valve 7 and the check valve 4 is required in the middle of the external pipe of the spool valve 1.

The purpose of this invention is to reduce the load on the fork W and the spool.
It is an object of the present invention to provide a control device capable of lowering a fork W at a stable speed regardless of a sudden operation of 1a.

(Means for Solving Problems) The present invention is based on the following configuration and is improved.

That is, a cylinder port and a pilot port are formed in the spool valve, the cylinder port is connected to the cylinder, and the cylinder port is connected to the supply passage and the return passage according to the switching direction of the spool provided in the spool valve. The opening degree of the communication passage is controlled according to the movement amount of the spool, and the flow from the cylinder port to the cylinder is a free flow.

Further, the present invention is based on the above-mentioned configuration, and an operating check valve that allows only the flow to the cylinder is provided in the cylinder port, and the poppet of the operating check valve is connected to the pilot chamber of the operating check valve. The pilot chamber is connected to the pilot passage, and the pilot passage and the return passage are connected to each other in accordance with the movement of the spool. Moreover, the pressure on the cylinder port side is detected and the flow passage of the pilot passage is formed. It is characterized in that a regulator valve for controlling the resistance to control the opening degree of the operate check valve is provided.

(Operation of the present invention) Since the present invention is configured as described above, when the spool is opened, the pilot chamber of the operate check valve communicates with the return passage, and the fluid on the cylinder side is formed in the poppet of the operate check valve. A flow path from the pilot chamber to the return passage is formed through the orifice and the regulator valve. Then, due to the pressure difference across the orifice, the operate check valve opens, forming a flow path from the cylinder port to the return passage, and the fluid in the cylinder flows out. When the fluid in the cylinder flows out, the regulator valve operates due to the fluid pressure difference between the cylinder port and the return passage, which occurs according to the amount of spool movement, and throttles the fluid outflow in the pilot chamber to control the lift of the operating check valve. To do.

(Effect of the present invention) According to the control device of the present invention, the fluid outflow amount of the cylinder is controlled according to the outflow amount as described above, even if the lowering speed of the fork changes depending on the load of the fork. Therefore, the descending speed of the fork is controlled. Therefore, if the switching stroke of the spool is kept constant, the fork can be lowered at the lowering speed according to the switching stroke.

Therefore, the operator does not need to control the switching stroke of the spool 1a while sensibly determining the change in the descending speed depending on the magnitude of the load, and this operation does not require skill.

Further, even if the stroke of the spool is suddenly operated beyond the desired stroke, the fork does not drastically descend, and the jumping descent phenomenon of the fork can be prevented.

(Embodiment of the Present Invention) The embodiment of the present invention shown in FIG.
The operation check valve 14 is installed inside, and the poppet 14a of the operation check valve 14 is made to face the pilot chamber 15, and the spring 16 provided in the pilot chamber 15 causes the poppet 14a to be pressed against the seat portion 17. I have to.

When the poppet 14a is in pressure contact with the seat portion 17 as described above, the inside of the cylinder port 2 is divided into the spool valve side 2a and the cylinder side 2b with the seat portion 17 as a boundary. An orifice 18 is formed in the poppet 14a, and the cylinder side 2b and the pilot chamber 15 are communicated with each other via the orifice 18.

Reference numeral 28 in the figure is a ball-shaped stopper.

The pilot room 15 as described above has a pilot passage 19
The pilot port 20 is communicated with the pilot port 20, and the pilot port 20 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 drill hole 21, a communication hole 24, and a regulator chamber 5. This regulator room 5
The piston 6 and spring s are installed inside,
A regulator passage 23 is provided on one side of the regulator chamber 5,
A communication hole 25 is formed on the other side. The tip of the regulator passage 23 is communicated with the spool side 2a of the cylinder port 2 through the first annular groove 9 of the spool 1a, and the communication hole
25 is the second annular groove 12 regardless of the switching position of the spool 1a.
It is configured such that the return passage 13 is always communicated with via.

Further, the piston 6 configured as described above forms the control portion 6a and the land portion 6b on the other side, and forms the annular recess 6c between the control portion 6a and the land portion 6b. There is. Moreover, the side surface of the control portion 6a on the side of the annular recess 6c is formed with a taper portion that gradually decreases in diameter toward the land portion 6b.

The outside of the control unit 6a of the piston 6 is connected to the first
Face the regulator passage 23 side communicated with the annular groove 9,
The outside of the land 6b faces the spring chamber 27 communicating with the communication hole 25.

A spring s is provided in the spring chamber 27, and normally the action of the spring s holds the piston 6 in the normal position shown. As described above, when the piston 6 is in the normal position, the drill hole 21 and the communication hole 24 maintain the fully opened state with respect to the annular recess 6c. However, when the piston 6 moves in the right direction in the drawing against the spring s, the opening of the drill hole 21 is gradually narrowed by the taper portion of the control portion 6a, and finally, the drill hole of the control portion 6a. I'm trying to close 21.

Further, an outflow hole 22 is formed in the first annular groove 9 on one side of the spool 1a. One end of the outflow hole 22 is always open to the first annular groove 9, while the other end communicates with the return passage 13 when the spool 1a is moved to the left.

The regulator chamber 5, the piston 6 and the spring s of this embodiment constitute the regulator valve of the present invention.

Then, when the spool 1a is moved to the right in the drawing, the supply passage 8 and the spool valve side 2a of the cylinder port 2 communicate with each other, so that the pressure fluid flows in the poppet of the operating check valve 14.
14a is pushed open to communicate with the bottom side chamber 3 of the cylinder S, and the fork W is raised.

If the spool 1a is returned to the neutral position shown in this state, the bottom side chamber 3 is closed by the poppet 14a of the operate check valve 14, so that the fork W can be held.

When the spool 1a is moved to the left in the drawing, the drill hole 21 opens in the pilot passage 20 and the fluid on the cylinder side 2b of the cylinder port 2 moves from the orifice 18 to the pilot chamber 15 to
Pilot passage 19 → Pilot port 20 flow path, that is, the pilot flow path, then drill hole 21 → annular recess 6c
→ communication hole 24 → flows to the return passage 13 through the second annular groove 12.

Therefore, a pressure difference is generated across the orifice 18, and the pressure on the upstream side of the orifice 18 causes the poppet 14a to move against the spring 16 to open the seat portion 17.

When the seat portion 17 is opened in this way, the fluid in the bottom side chamber 3 flows out to the return passage 13 via the spool side 2a of the cylinder port 2 → the outflow hole 22.

At this time, the fluid pressure on the spool side 2a acts on the control portion 6a of the piston 6 via the regulator passage 23 formed in the spool 1a, and the fluid pressure on the return passage 13 faces the spring chamber 27. Acts on 6b.

Now, when the load of the fork W is large and the descending speed of the load is about to increase with respect to the switching stroke of the spool 1a, the outflow amount of the fluid from the cylinder S increases, and the differential pressure before and after the outflow hole 22 is accordingly increased. growing. When this differential pressure becomes equal to or higher than the set pressure of the spring s that acts on the piston 6, the piston 6 moves to a position that balances the spring force while bending the spring s. When the piston 6 moves in this way, the controller 6a controls the opening of the drill hole 21 at the moving position.

When the poppet 14a moves and the flow path is narrowed together with the seat portion 17, the fluid flow rate on the spool valve side 2a of the cylinder port 2 decreases, and the fluid pressure difference between the spool valve side 2a and the return passage 13 decreases. Therefore, in the piston 6, the drill hole 21 of the spool 1a is opened by the spring force of the spring s.

Then, as described above, the flow path that flows out to the return path 13 via the pilot flow path is formed again, and the poppet 14a opens to allow the fluid in the bottom side chamber 3 of the cylinder S to flow out.

As described above, when the poppet 14a is opened and the fluid in the cylinder S flows out to the return passage 13 through the spool valve side 2a of the cylinder port 2 → the outflow hole 22, the spool valve side 2a and the return passage 13 are formed.
The piston 6 moves in accordance with the pressure difference between and, and the pilot flow passage is throttled. Therefore, the opening of the operate check valve is controlled in accordance with the throttling action, and the amount of fluid outflow from the cylinder is automatically controlled.

Therefore, the lowering speed of the fork is controlled even if the lowering speed is about to change depending on the magnitude of the load on the fork. Therefore, if the switching stroke of the spool is kept constant, the fork can be lowered at the lowering speed according to the switching stroke.

Therefore, the operator does not need to control the switching stroke of the spool 1a while sensibly determining the change in the descending speed depending on the magnitude of the load, and this operation does not require skill.

Further, when the stroke of the spool 1a is suddenly operated beyond the desired stroke, the fork W does not suddenly descend and the jumping phenomenon does not occur.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional device. 1 ... Spool valve, 1a ... Spool, 2 ... Cylinder port, S ... Cylinder, 5 ... Regulator chamber, 8 ...
Supply passage, 13 ... Return passage, 14 ... Operate check valve, 14a ... Poppet, 15 ... Pilot chamber, 18 ... Orifice, 19 ... Pilot passage, 20 ... Pilot port The s ...... spring that composes the regulator valve.

Claims (1)

[Scope of utility model registration request] A cylinder port and a pilot port are formed in a spool valve, the cylinder port is connected to a cylinder, and the cylinder port is used as a supply passage or a return passage according to a switching direction of a spool provided in the spool valve. In a cylinder control device configured to communicate with each other, the opening degree of the communication passage is controlled according to the movement amount of the spool, and the flow from the cylinder port to the cylinder is a free flow, only the flow to the cylinder is allowed. An operating check valve is installed in the cylinder port, an orifice is formed in the poppet of the operating check valve to communicate with the pilot chamber of the operating check valve, and the pilot chamber is communicated with the pilot passage, and the pilot is moved according to the movement of the spool. The passage and the return passage are communicated with each other. Cylinder control apparatus characterized in that a regulator valve which detects the pressure of the cylinder port side controls the opening of the operate check valve to control the flow resistance of the pilot passage.