JPS623323B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cylinder device, and more particularly to a single-acting cylinder device driven by working fluid that is compressed in the head side direction and flows in and out of the head side cylinder chamber.

For example, when controlling the friction between the plates of suspension stacked leaf springs in order to improve the riding comfort and handling stability of a vehicle, it is desirable that the piston stroke be short and that it be small and lightweight. Type cylinder devices are preferred. As shown in FIG. 1, this type of cylinder device includes a cylinder body 1 and a piston 2 slidably fitted into the cylinder body 1, and the working fluid flows into and out of the head side cylinder chamber 4 through the flow port 3. A disc spring 6 is provided in the rod side cylinder chamber 5 to press the piston 2 toward the head side. In order to reduce the size, the piston head 2a is formed to have a short axial length, and the cylindrical guide portion 7 for the piston rod 2b is also formed to be short. Therefore, the piston 2 is likely to be tilted or eccentric due to lateral loads, which may cause twisting of each sliding part or damage to the O-ring 8, hindering smooth operation and resulting in poor durability. There are some difficulties.

The present invention was made under the above circumstances, and its purpose is to prevent the piston from tilting or eccentricity despite being short and small, thereby ensuring smooth operation over a long period of time. An object of the present invention is to provide a cylinder device.

Hereinafter, the present invention will be described with reference to illustrated embodiments. In the first embodiment shown in FIG. 2, the cylinder body 10 has a cylinder chamber 11 formed therein, and has a working fluid communication port 13 formed in the head side end cover 12 and communicating with the cylinder chamber 11. , has an annular guide member 15 provided on the rod side end cover 14. The piston 16, which is slidably fitted into the main body 10, integrally includes a piston head 16a which is fitted fluid-tightly into the cylinder chamber 11, and a piston rod 16b which passes freely through the guide member 15. A piston ring 1 is inserted into a circumferential groove 17 formed on the outer periphery of the piston head 16a.
8 and a backup spring 19 are fitted. The cylinder chamber 11 is a piston head 16a.
It is divided into a head side cylinder chamber 11a and a rod side cylinder chamber 11b. A return spring member 20 such as a disc spring, which is located between the rod end cover 14 and the piston head 16a and presses the piston 16 toward the head side, is interposed in the rod side cylinder chamber 11b. The above general configuration is the first
It may be similar to the normal cylinder device shown in the figure.

A piston 16 is disposed between the head side end cover 12 of the main body 10 and the piston head 16a.
A positioning spring member 21 is interposed to hold the positioning member substantially concentrically. That is, the head end cover 12 is provided with a protrusion 22 whose outer periphery is concentric with the peripheral wall of the cylinder chamber 11. Further, the piston head 16a is formed with a recess 23 having an inner circumferential wall concentric with the outer circumference of the piston head 16a. The spring member 21 is, for example, a disc spring, and has an inner circumference fitted into the protrusion 22 and an outer circumference fitted into the recess 23. This spring member 21 has a spring constant smaller than that of the above-mentioned return spring member 20 installed in the rod side cylinder chamber 11b, and if necessary, a third
It may also be star-shaped as illustrated in the figure.

According to the above configuration, when the working fluid is pressurized into the head side cylinder chamber 11a through the flow port 13,
The piston 16 is driven toward the rod side against the elastic force of the return spring member 20, and when the pressure of the working fluid decreases, it is moved toward the head side by the elastic force of the return spring member 20. A positioning spring member 21 is interposed between the outer peripheral wall of the recess 23 of the piston head 16a and the protrusion 22 of the head side end cover 12, so that the piston head 16
Eccentricity of a is effectively prevented. Furthermore, since both the piston head 16a and the piston rod 16b are formed short, eccentricity of the piston rod 16b is also suppressed. Therefore, there is no galling at the mutual sliding contact portions or damage to the O-ring 18, so stable and smooth operation can be achieved over a long period of time.

In the second embodiment shown in FIG. 4, the protrusions 22 are extended in the axial direction, are located at the same position in the axial direction, are arranged at equal pitches in the circumferential direction, and communicate with the communication port 13. A plurality of radial openings 30 are provided. Further, a recess 31 is formed in the piston 16, which is concentric with the piston 16 and into which the protrusion 22 can be loosely fitted. Since the other parts are substantially the same as those in the first embodiment, corresponding parts are denoted by the same symbols as in FIG. 1 and the explanation thereof will be omitted.

In this second embodiment, the same effects as in the above-mentioned first embodiment are achieved, and
Suppose that the piston 16 is eccentric as shown in FIG. 5 due to a lateral load, the opening 30
The flow rate of the working fluid flowing in and out of the piston 16 increases and the pressure decreases in the region A, which is widened due to eccentricity, while the flow rate decreases and the pressure increases in the narrowed region B, causing the piston 16 to It acts to hold it in the normal position. Therefore, eccentricity of the piston can be more effectively prevented.

It should be noted that the present invention is not limited to the above-mentioned embodiments. For example, spring members having various other configurations may be used instead of the dish-shaped spring as the return spring member 20 that presses the piston 16 toward the head side. Moreover, the position where it is provided is not limited to the rod side cylinder chamber, but can be installed at any other desired position, and various changes and applications are possible within the scope of the gist of the present invention.

As described above, the present invention has a main body through which working fluid flows in and out only into the head side cylinder chamber, and a piston fitted into this main body so as to be able to reciprocate in the axial direction. The piston is characterized in that a spring member is interposed between the piston and the top of the piston to hold the piston substantially concentrically with the main body. Therefore, the above-mentioned piston does not become eccentric even when subjected to a lateral load, and it is possible to effectively prevent the occurrence of twisting or damage in the mutual sliding contact area, and it can be maintained stably and smoothly for a long period of time. can perform actions.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a normal single-acting cylinder device, FIG. 2 is a sectional view showing an embodiment of the present invention, and FIG. 3 is an explanatory diagram showing a modification of the main parts of the same example.
FIG. 4 is a sectional view showing another embodiment of the present invention, and FIG. 5 is an explanatory diagram of the operation of the same embodiment. 10...Cylinder body, 11...Cylinder chamber, 11
a... Head side cylinder chamber, 12... Head side end cover,
DESCRIPTION OF SYMBOLS 11... Flow port, 16... Piston, 20... Spring member for return, 21... Spring member for positioning, 22... Protrusion, 23... Recessed part, 30... Opening part, 31... Recessed part.

Claims (1)

[Claims] 1. In a device having a main body through which working fluid flows in and out only into the head-side cylinder chamber, and a piston fitted into the main body so as to be able to reciprocate in the axial direction, the head-side end of the main body and the top of the piston A cylinder device characterized in that a spring member is interposed between the piston and the main body to hold the piston substantially concentrically with the main body.