JPH10205570A - Cylinder device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact cylinder device with excellent machinability, assembly and profitability without restricting a mounting space. SOLUTION: For a cylinder device, a piston rod 3 is inserted in a cylinder tube 1 via a piston 2 to be freely moveable, the piston 2 has two oil chambers 4, 5 formed in the cylinder tube 1 to be mutually communicated via a bypass R and an open/closed valve is provided in the bypass R to be freely open/closed. The bypass R is formed in the piston rod 3 and the open/closed valve is provided in the piston rod 3 to open/close the bypass R so that the open/closed valve can be open/closed from the outside via a bush rod 10 passing through the piston rod 3 to be freely movable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder device suitable for use with, for example, a rear wheel suspension of a reach type forklift truck.

[0002]

2. Description of the Related Art As a cylinder device used for a rear wheel suspension of a reach type forklift truck, for example, a cylinder device disclosed in JP-A-6-191250 is known. In this cylinder device, piston rods on both sides of the piston are movably inserted into a cylinder tube via a piston, two oil chambers are defined in the cylinder tube, and the two oil chambers are connected via a bypass outside the cylinder tube. In the middle of the bypass, an electromagnetic on-off valve is provided to be openable and closable, the two piston rods are respectively connected to the body frame and the link mechanism, and the on-off valve is controlled by signals from a vehicle speed sensor and a tilt acceleration sensor. It is made to be done. In this case, the valve body having the bypass formed is assembled separately from the cylinder tube. Further, in this cylinder device, during normal running of the forklift truck, the on-off valve is opened so that the piston rod can be operated, so that the suspension spring provided in the link mechanism is operated to absorb vibrations and the like. On the other hand, at the time of cargo handling work at high elevation, at low speed, or when turning sharply, the on-off valve is closed by a signal from the vehicle speed sensor or the tilt acceleration sensor, and the movement of the piston rod is locked to prevent the suspension spring from operating. To stabilize the vehicle body.

[0003]

However, in the above-described cylinder device, the cylinder tube and the valve body are formed separately, and the valve body is attached to the outside of the body of the cylinder tube. And, for example, when installed on a reach-type forklift truck, the installation space is limited.

Further, since the valve body is formed separately from the cylinder tube, the processing cost is increased, and the processing of the valve body is difficult, so that the workability and the assembling property are inferior.

Therefore, an object of the present invention is to provide a compact
An object of the present invention is to provide a cylinder device which is not restricted in mounting space and is excellent in workability, assemblability, and economy.

[0006]

In order to achieve the above-mentioned object, the present invention provides a cylinder tube having a piston rod movably inserted through a piston, and the piston having two oil chambers in the cylinder tube. In a cylinder device in which two oil chambers communicate with each other via a bypass and an open / close valve is provided in the bypass so as to be openable and closable, a bypass is formed in the piston rod, and the bypass is opened and closed in the piston rod. The opening and closing valve is provided, and the opening and closing valve is operated to be opened and closed from the outside via a push rod movably penetrating through the piston rod.

In this case, the piston and the piston rod are integrally formed, a bypass is formed in the piston rod so as to bypass the piston, and a valve housing is provided in the piston rod. A communication port is formed, a poppet-type opening / closing valve for opening / closing the port is provided in the valve housing, and a push rod facing the opening / closing valve is movably inserted into the piston rod. It is preferable that when the solenoid provided at the outer end of the piston rod is excited, the open / close valve is biased in the opening direction.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

In the cylinder device of the present invention, a double rod type piston rod 3 is movably inserted into a cylinder tube 1 via a piston 2, and the piston 2 partitions two oil chambers 4, 5 in the cylinder tube 1. And two oil chambers 4,5
Is connected through a bypass R, and an opening / closing valve 6 is provided in the bypass R so as to be openable and closable.

In this case, the piston 2 and the piston rod 3
Are integrally formed, and the piston 2 is
Is formed, and a valve housing 7 is provided in the piston rod 3. Ports 8 and 9 communicating with the bypass R are formed in the valve housing 7. A poppet-type opening / closing valve 6 for opening and closing the ports 8 and 9 is provided. A push rod 10 facing the opening / closing valve 6 is inserted into the piston rod 3 so as to be movable in the axial direction. Solenoid 11 provided at outer end
Is energized in the direction in which the on-off valve 6 is opened at the time of excitation.

The details will be described below.

Caps 1 are provided on both sides of the cylinder tube 1.
The left and right rods 3a, 3b, which are both rod type piston rods 3, are movably penetrated through the inner circumference of the caps 12, 13 via an oil seal 14, a dust seal 15, and a bearing 30. I have.

The piston 2 and the piston rod 3 are integrally formed, and the piston 2 slides on the inner periphery of the cylinder tube 1 via a seal member 16 on the outer periphery.

A bypass R bypassing the piston 2 is composed of a passage 17 opening to one oil chamber 4 and a passage 18 opening to the other oil chamber 5, and a hollow valve housing 7 is connected midway between the passages 17 and 18. Is inserted.

A spring seat 19 is connected to an end of the valve housing 7 via a snap ring. Ports 8 and 9 are formed in the spring seat 19 and the body of the valve housing 7 to open to passages 17 and 18, respectively. ing. It is preferable that one port 9 also serves as a throttle.

A spring 20 is interposed between the spring seat 19 and the pocket type valve body 6a of the opening / closing valve 6, and this spring 20 is provided for the valve seat having the valve body 6a formed in the valve housing 7. To shut off the communication between the normal ports 8 and 9.

A port penetrates through the center of the opening / closing valve 6 so that a pressure difference does not occur on both sides of the opening / closing valve 6.

In the piston rod 3, a hollow guide rod 21 is inserted into one of the rods 3b along the axial direction.
And is locked to the outer end of the rod 3b via a flange 23. A cylindrical portion 21a is formed in the inner diameter of the guide rod 21, and the end of the valve housing 7 is press-fitted into the cylindrical portion 21a.

The push rod 10 is movably inserted into the guide rod 21 along the axial direction, and the inner end of the push rod 10 faces the end of the on-off valve 6.

A casing 25 constituting the solenoid 11 is connected to an outer end of the guide lot 21 via a screw 24, and a solenoid coil 26 is disposed in the casing 25. As a result, when the solenoid 11 is excited, the push rod 10 is pushed leftward in the drawing and moves, and the push rod 10 pushes the opening / closing valve 6 open against the spring 20 to communicate the ports 8 and 9. To open the bypass R. When the solenoid 11 is demagnetized, the opening / closing valve 6 is pushed by the spring 20 to shut off the communication between the ports 8 and 9 again and close the bypass R.

When the bypass R is closed as described above, there is no oil flow between the two oil chambers 4 and 5, the piston 2 and the piston rod 3 are locked, and when the bypass R is opened, the piston 2 and the piston rod 3 can move left and right in the figure. Note that, instead of the solenoid 11, another actuator such as a gear may be used.

Next, the operation when the above-described cylinder device is used as a rear wheel suspension of a reach type fork truck will be described.

The solenoid 11 is not energized when carrying out the cargo handling operation at low speed or when the vehicle is at a high elevation, whereby the opening / closing valve 6 is at the position shown in the figure and the valve body 6a closes the bypass R. Also in the case of a sharp turn, the excitation of the solenoid 11 is stopped by a signal from the tilt acceleration sensor, and the open / close valve 6 is closed. Therefore, no oil flows from the bypass R, the piston rod 3 does not operate, and the cylinder device is locked. Accordingly, the link mechanism is also locked because the suspension spring does not move, so that the vehicle body does not move up and down, thereby stabilizing the vehicle body.

On the other hand, when the vehicle normally travels, the solenoid 11 is excited by a signal from the vehicle speed sensor, and the valve body 6a
Is opened, the two oil chambers 4 and 5 communicate with each other via the bypass R, and the piston rod 3 becomes operable, whereby the suspension spring operates to absorb vibrations to the vehicle body and improve riding comfort. When the port 9 is configured as a throttled orifice, when oil flows through the bypass R when the piston rod 3 is operated, the oil is throttled by the orifice and abrupt impact on the vehicle body is attenuated.

[0025]

According to the present invention, the following effects can be obtained.

(1) According to the invention of each claim, since the bypass communicating the two oil chambers is formed in the piston rod, the bypass and the open / close valve in the bypass are connected to the outside of the cylinder tube as in the prior art. Need not be provided in the valve body, and the diametrical dimension of the entire cylinder device is reduced, whereby the whole is compact and the mounting space is not restricted.

(2) Similarly, since a bypass, an on-off valve and a push rod are provided in the piston rod,
A separate valve body is not required, the workability is improved, the processing cost is reduced, and since these members can be assembled together with the piston rod, the ease of assembly is improved.

(3) According to the second aspect of the present invention, since the piston and the piston rod are formed integrally, the workability and the assemblability of both are improved.

[Brief description of the drawings]

FIG. 1 is a vertical sectional front view of a cylinder device according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder tube 2 Piston 3 Piston rod 4,5 Oil chamber 6 On-off valve 7 Valve housing 8,9 Port 10 Push rod 11 Solenoid R Bypass

Claims (2)

[Claims] A piston rod is movably inserted into a cylinder tube through a piston, the piston partitions two oil chambers in the cylinder tube, and the two oil chambers communicate with each other through a bypass. In a cylinder device in which an open / close valve is provided so as to be openable and closable, a bypass is formed in a piston rod, and an open / close valve for opening and closing the bypass is provided in the piston rod, and the open / close valve movably penetrates the piston rod. A cylinder device which is opened and closed from the outside via a push rod. 2. A piston and a piston rod are integrally formed, a bypass is formed in the piston rod to bypass the piston, and a valve housing is provided in the piston rod, and the valve housing communicates with the bypass. A poppet-type opening / closing valve for opening / closing the port is provided in the valve housing, and a push rod facing the opening / closing valve is movably inserted into the piston rod. 2. The cylinder device according to claim 1, wherein the solenoid valve is biased in a direction to open the on-off valve when a solenoid provided at an outer end of the rod is excited.