JP2002235701A - Hydraulic control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a hydraulic control device compactly at a low cost. SOLUTION: A first selector part 17a for opening a hydraulic fluid passage 32 allowing a cylinder port 4 to communicate with a suction port 5 and a second selector part 17b for opening a hydraulic fluid passage 31 to allow the cylinder port 4 to communicate with a discharge port 6 are provided on the left and right sides of a spool fitted into a sleeve 18 of a directional control valve 1 movably in forward and backward directions, and a flow control valve 3 is installed in the fluid passage 31 to allow the cylinder port 4 to communicate with the discharge port 6. Thus a hydraulic fluid can be led into the cylinder port 4 without passing the resistive flow control valve 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control device used for an industrial vehicle, a lift device, and the like.

[0002]

2. Description of the Related Art For example, a conventional hydraulic pressure control device for controlling a cylinder or the like of a lift device, as shown in FIG.
The directional control valve 20 includes a flow control unit 25 provided outside the directional control valve 20.

[0003] A sleeve 29 is provided in a valve housing 28 of the directional control valve 20.
9 is provided with a suction port 22 connected to a high pressure source, a discharge port 23 communicating with a low pressure source, and a cylinder port 21.

The spool 3 sliding in the sleeve 29
One switching unit 33a for opening the flow path 34 that connects the cylinder port 21 and the suction port 22 and the opening of the flow path 35 that connects the cylinder port 21 and the discharge port 23 are reciprocal. Is provided.

The flow control unit 25 is provided at a position where the cylinder port 21 of the direction control valve 20 communicates with the cylinder 24, and as shown in FIG. 4, a check valve for preventing backflow of the hydraulic fluid in the cylinder 24. 26 and cylinder 2
A flow control valve 27 is provided for restricting the amount of hydraulic fluid flowing out of the cylinder 24 when the cylinder 4 is contracted, thereby restricting the operating speed of the cylinder 24.

FIG. 3 shows a state where the spool 33 is at the neutral position.

When the spool 33 is in the right-hand position, the switching section 33a of the spool 33 opens the flow path 34 that connects the suction port 22 and the cylinder port 21, and the high-pressure hydraulic fluid flowing from the suction port 22 is discharged. Flow control unit 2
The cylinder 24 extends by flowing into the cylinder 24 through the check valve 26 of No. 5.

On the other hand, when the spool 33 is at the left-hand position, the switching unit 33a of the spool 33 causes the discharge port 2 to move.
The flow path 35 communicating the cylinder port 3 with the cylinder port 21 is opened, and the hydraulic fluid in the cylinder 24 flows out through the flow control valve 27 of the flow control unit 25, so that the cylinder 24 contracts.

When the spool 33 is in the neutral position, the cylinder port 21 is connected to the suction port 22 and the discharge port 23.
Blocked from.

[0010]

However, the flow control unit 2
In the illustrated example of the hydraulic pressure control device in which the valve 5 is provided outside the direction control valve 20, the connection space for connecting the flow rate control unit 25 and the connection process of the piping for the connection are required, thereby increasing the cost. Occurs.

Further, since the hydraulic fluid must flow into the cylinder 24 through the check valve 26 provided in the flow control unit 25, energy loss due to the pressure loss of the hydraulic fluid occurs, and unnecessary hydraulic fluid is generated. Problems such as a rise in temperature and an inability to increase the extension speed of the cylinder 24 also occur.

The hydraulic pressure control device for solving the above-mentioned problems has basically the same configuration as the above-mentioned hydraulic pressure control device, except that the flow control unit is directly connected to the cylinder port of the valve housing of the directional control valve. Some have been attached.

Certainly, in such a fluid pressure control device, it is possible to solve the problems such as the necessity of a space for connecting the flow rate control unit and the step of connecting the piping.

However, there is no difference in that the working fluid must flow through the check valve of the flow control unit when flowing into the cylinder, and the problem of energy loss of the working fluid cannot be solved.

[0015]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a sleeve, a suction port, a discharge port, and a cylinder port connected to the sleeve, and is fitted to the sleeve so as to be able to advance and retreat. A first switching unit for opening a flow path of hydraulic fluid that communicates the cylinder port and the suction port, and a second switching unit for opening a flow path of hydraulic fluid that communicates the cylinder port and the discharge port. And a flow control valve for controlling the flow rate of the hydraulic fluid in the flow path of the hydraulic fluid communicating the cylinder port and the discharge port are integrally provided in the valve housing. The hydraulic pressure control device is characterized in that:

As described above, in the present hydraulic pressure control device, a flow path which is opened by the second switching section and communicates with the cylinder port and the discharge port is separately formed, and a flow control valve is provided in the flow path. ing.

[0017] Therefore, a piping space or the like required when the flow control valve is connected to the outside of the directional control valve can be omitted, and further, a flow path in which the suction port and the cylinder port are communicated by the first switching unit. If you open
The hydraulic fluid can flow into the cylinder without passing through the flow control valve.

As a result, it is possible to prevent pressure loss of the working fluid and unnecessary rise in the temperature of the working fluid, thereby making it possible to increase the extension speed of the cylinder.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

In this embodiment, a case where the hydraulic pressure control device of the present invention is mounted on a forklift will be described.

As shown in FIG. 1, the present hydraulic pressure control device comprises a direction control valve 1 and a flow control valve (down control valve) 3.

A sleeve 18 is provided in the valve housing 16 of the directional control valve 1.
Is provided with a suction port 5 connected to a high pressure source, a discharge port 6 communicating with a low pressure source, and a cylinder port 4. The spool 1 sliding in the sleeve 18
A first switching unit 1 for opening the flow path 32 of the hydraulic fluid that connects the cylinder port 4 and the suction port 5 is provided on the left and right sides of the first switching unit 1.
7a and a second switching unit 17b for opening the flow path 31 of the hydraulic fluid that communicates the cylinder port 4 and the discharge port 6.
Are provided separately, and their switching units operate reciprocally.

A flow control valve 3 for limiting the amount of hydraulic fluid flowing out of the cylinder 7 is provided in a flow path 31 connecting the cylinder port 4 and the discharge port 6, specifically, a second switching section. It is provided in the flow path upstream of 17b.

Consider a case in which the lift is moved up and down by controlling the cylinder 7 by the hydraulic pressure control device having the above-described configuration.

First, the case of raising the lift.

In this case, the spool 17 of the direction control valve 1 is moved rightward in FIG.

Then, contrary to the closing of the flow path 31, the flow path 32 is opened by the first switching section 17a, and the high-pressure hydraulic fluid flowing in from the suction port 5 passes through the flow path 32 to the cylinder port 4 From the cylinder 7, the cylinder 7 expands, and the lift rises.

That is, in this case, the hydraulic fluid passes through the suction port 5 and the cylinder port 4 in order, flows into the cylinder 7, and the lift rises.

The case where the lift is lowered.

In this case, the spool 17 of the direction control valve 1 is moved to the left in FIG.

Then, contrary to the closing of the flow passage 31, the flow passage 31 is opened by the second switching portion 17b, and the hydraulic fluid from the cylinder port 4 flows out to the discharge port 6 through the flow control valve 3. Then, the cylinder 7 contracts and the lift descends.

That is, in this case, the hydraulic fluid passes through the cylinder 7, the cylinder port 4, and the flow control valve 3 in order, and is discharged from the discharge port 6.

As described above, the hydraulic control device of the present invention
The flow control valve 3 is replaced with the valve housing 1 of the directional control valve 1.
Since the structure integrated with the flow control valve 6 is adopted, it is possible to eliminate a connection space and a pipe connection step required when the flow control valve 3 is provided outside.

The spool 17 is provided with a first switching portion 17a and a second switching portion 17b, and the flow control valve 3 is provided in a flow path 31 that connects the cylinder port 4 and the discharge port 6. Therefore, when the lift is lifted, the hydraulic fluid flows into the cylinder 7 from the flow path 32 that connects the cylinder port 4 and the suction port 5 without passing through the flow control valve 3.

As a result, it is possible to prevent pressure loss of the working fluid and unnecessary rise in the temperature of the working fluid, and it is possible to increase the extension speed of the cylinder 7.

In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

For example, in the above-described embodiment, the lift lock is performed by the land of the spool 17. However, if an electromagnetically driven lift lock valve is provided in the flow path 32 connecting the cylinder port 4 and the suction port 5, the cylinder 7 can be locked. It is possible to completely prevent the backflow of the working fluid in the inside, and it is possible to reduce the amount of the cylinder 7 naturally descending.

In this embodiment, a sectional type valve including only one directional control valve is shown. However, the present invention is also applied to a monoblock type valve in which a plurality of directional control valves are integrated. It is possible.

[0039]

The present invention is embodied in the form described above, and has the following effects.

That is, in the present invention, the second
A fluid pressure control device is provided that forms a flow path that connects the cylinder port and the discharge port so as to be opened by the switching unit, and that is provided with a flow control valve in the flow path.

Accordingly, it is possible to omit the piping space and the connection process required for the hydraulic pressure control device in which the flow control valve is provided outside the direction control valve, and to reduce the size and cost of the device. Will be possible.

Further, by opening the flow path connecting the suction port and the cylinder port by the first switching section, it becomes possible to make the hydraulic fluid flow into the cylinder without passing through the flow control valve, and to reduce the pressure loss of the hydraulic fluid and the hydraulic fluid. In addition, it is possible to prevent unnecessary temperature rise of the hydraulic fluid, and at the same time, increase the operating speed of the cylinder, thereby dramatically increasing the function related to the hydraulic pressure control.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a directional control valve showing an embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram of the embodiment.

FIG. 3 is a schematic sectional view of a conventional directional control valve.

FIG. 4 is a conventional hydraulic circuit diagram.

[Explanation of symbols]

 3 ... Flow control valve 4 ... Cylinder port 5 ... Suction port 6 ... Discharge port 16 ... Valve housing 17 ... Spool 17a, 17b ... Switching unit (first switching unit, second switching unit) 18 ... Sleeve

Claims (1)

[Claims] A sleeve, a suction port, a discharge port, and a cylinder port connected to the sleeve, and an open / close passage of a hydraulic fluid that is fitted to the sleeve so as to be able to move forward and backward and communicates the cylinder port and the suction port. A spool for separately operating and reciprocally operating a switching unit for performing the operation and a switching unit for opening the flow path of the hydraulic fluid that communicates the cylinder port and the discharge port; and connecting the cylinder port and the discharge port. A fluid pressure control device, wherein a flow control valve for controlling the flow rate of the working fluid in a flow path of the working fluid is provided integrally with the valve housing.