JPH10141319A - Hydraulic cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To design a hydraulic cylinder compact in size in terms of structure by installing a guide rod and a guide member, regulating any shafting rotation, in a piston and a piton rod core part. SOLUTION: An end 25a of a guide rod 25 is fitted in a through hole 20c installed in a core part of a fixture 20, and thereby it is secured by a diametral pin 26. The guide rod 25 is made up as a spline rod having a section with a projecting bar. When pressure fluid, for example, pressure oil is supplied from a suction-discharge port 14 at the rear side, a piston 3 is pushed and advanced forward, and thereby a piston rod 4 is extended. In contrast with this, when the pressure oil is supplied from another suction-discharge port 11 at the front side, this piston rod 4 is contracted to some extent. A guide member 30 with a spline flute is attached tight to the piston 3 to which the piston rod 4 is attached tight likewise, and this guide member 30 is fitted in the guide rod 25 or a spline shaft by means of a spline. Accordingly, and shafting rotation of the piston 3 and the piston rod 4 is thus regulable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid cylinder such as a hydraulic cylinder or an air cylinder which expands and contracts by a fluid pressure.

[0002]

2. Description of the Related Art Fluid cylinders such as hydraulic cylinders and air cylinders are used as driving sources for various mechanical devices.
In this type of cylinder, a piston with a circular cross section is provided so as to be movable back and forth inside a cylinder tube having a space with a circular cross section, and a piston rod integral with this piston projects from the end of the cylinder tube and expands and contracts. The piston rod is used to pressurize or drive another object.

Incidentally, in the above-mentioned conventional general fluid cylinder, the piston has a circular cross section and is housed in a hollow portion having a circular cross section of the cylinder tube, so that the piston can only reciprocate in the axial direction of the cylinder tube. However, when an external force was applied, the cylinder rotated around the axis in the cylinder tube.

On the other hand, depending on the application of these fluid cylinders, it is often necessary to restrict the piston rod from rotating around its axis when, for example, a mold is used in a hydraulic press. The method conventionally used as a method for restricting the rotation of the piston rod is to provide a pair of left and right guide rods along the axial direction outside the cylinder tube, and slidably fit a guide member provided on the piston rod into this. And a method in which the cross-sectional shape of the piston rod is square.

[0005]

However, if the guide rod is provided outside the cylinder tube, there is a problem that the volume is increased by that amount, which often hinders the design. Further, in the method of making the cross-sectional shape of the piston rod square, it is difficult to seal the sliding portion with the cylinder tube, and this seal material is not only expensive, but also it is difficult to obtain a perfect seal. there were.
Therefore, an object of the present invention is to provide a structure capable of restricting rotation of a piston rod in a fluid cylinder without increasing its volume or reducing a sealing effect.

[0006]

In order to solve the above problems, the present invention employs the following configuration. That is, the fluid cylinder according to the present invention is a fluid cylinder in which a piston is provided in a cylinder tube and a piston rod attached to the piston projects from the cylinder tube.
The piston and the piston rod are formed hollow, and a polygonal or spline-shaped guide rod fixed to the end of the cylinder tube is inserted through the hollow portion of the piston and the piston rod, and the hollow portion of the piston or the piston rod is inserted. The portion is provided with a hollow guide member which is non-rotatably and slidably fitted to the guide rod.

In this fluid cylinder, a piston rod and a piston are formed as hollow bodies, and a guide rod fixed to a cylinder tube is fitted into these hollow parts so as to be non-rotatable and slidable. Rotation can be prevented without affecting the extension and contraction of the rod.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to specific examples. The figure shows a specific example of the fluid cylinder 1. The fluid cylinder 1 has a piston 3 slidably fitted inside a cylindrical cylinder tube 2. A piston rod 4 is attached to the piston 3.

Ring-shaped flanges 5 and 5 are fixed to the front and rear ends of the cylinder tube 2 by welding, and front and rear lid members 6 and 7 are fixed to the cylinder tubes 2 by bolts 8.
The front lid member 6 includes a flange portion 6a and a cylindrical portion 6b fitted inside the cylinder tube 2, and a circular hole 10 for inserting a piston rod is provided in a core portion. Further, a suction / discharge port 11 provided on an outer peripheral portion of the flange portion 6a.
A through hole 12 communicating with the inside 6c of the cylindrical portion 6b is provided.

The rear lid member 7 also includes a flange portion 7a and a cylindrical portion 7b in the same manner as described above, and communicates with an end surface of the cylindrical portion 7b through a suction / discharge port 14 provided on an outer peripheral portion of the flange portion 7a. A through hole 15 is provided.

A counterbore 17 is provided at the bottom of the inside 7c of the cylindrical portion 7b.
It is fixed at 1, ... The fixing device 20 includes a cylindrical portion 20a and a flange portion 20b, and a through hole 20
c is provided. The end 25a of the guide rod 25 is fitted into the through hole 20c, and is fixed by a diametric pin 26. The guide rod 25 is formed as a spline rod having a cross section with ridges 25b as shown in FIG. Such a cross-sectional shape is used in order to provide a detent function by fitting with a later-described guide member, but it may be a polygonal shape as shown in FIG. 3, for example. In this case, a guide member described later has a fitting hole having a polygonal cross section to be fitted to the polygonal rod.

The piston 3 provided inside the cylinder tube 2 has a substantially cylindrical shape, and a guide member 30 that fits non-rotatably and slidably on the guide rod 25 is fitted therein. Installed. The guide member 30 is formed as a cylindrical body having a spline grooved through hole 31 for fitting the guide rod 25, and a flange portion 32 is integrally provided at a rear end thereof. .. Are fixed to the piston by bolts 33,. Numerals 35 and 35 in the figure are sealing materials. The guide rod 25 and the guide member 3
The combination of 0 is a commercially available ball spline.
Units can be used. Further, in some cases, the piston or the piston rod itself may be processed as a guide member that is fitted to the guide rod so as not to rotate.

The piston rod 4 fixed to the front end of the piston 3 is cylindrical, and the inner diameter of the hollow portion of the piston rod 4 is large enough to fit the guide rod 25 slidably. The front end of the piston rod 4 is closed by a plug 37 having a fitting boss 37a and a mounting boss 37b. This piston rod 4
Are slidably fitted in the core hole 10 of the front lid member 6. 38 in the figure are seal materials.

In this fluid cylinder, generally, a rear end portion (a lid member 7 and the like) of the cylinder tube 2 is fixed to a machine frame or the like, and an object to be driven is mounted on a mounting boss portion 37b at a front end portion of the piston rod 4. Used to be attached. When a pressure fluid, for example, pressure oil is supplied from the suction / discharge port 14 on the rear side in the state of FIG. 1, the piston 3 is pushed to move forward, and the piston rod 4 is extended. Conversely, when pressure oil is supplied from the suction / discharge port 11 on the front side, the piston rod 4 contracts. A guide member 30 having a spline groove 30a is fixed to the piston 3 to which the piston rod 4 is fixed, and the guide member 30 is spline-fitted to the guide rod 25 which is a spline shaft. The rotation of the rod 4 around the axis is also restricted.

[0015]

As is apparent from the above description, the fluid cylinder according to the present invention is provided with the guide rod and the guide member for regulating the rotation around the axis at the core of the piston and the piston rod. No rotation around the rod axis occurs. This fluid cylinder does not have a guide rod outside the cylinder tube as in a conventional cylinder, so that the guide rod or the like does not interfere with the use of the fluid cylinder and can be designed compact. In addition, since the piston rod has a cylindrical shape, sealing with the cylinder tube outlet can be easily and completely performed, and leakage of the pressurized fluid during use does not occur. Although the fluid cylinder in the illustrated example is a hydraulic cylinder, it goes without saying that the present invention can be applied to other hydraulic cylinders, air cylinders, and the like.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along line XX in FIG.

FIG. 3 is a cross section of a different embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fluid cylinder 2 Cylinder tube 3 Piston 4 Piston rod 25 Guide rod 30 Guide member

Claims (1)

[Claims] 1. A piston is provided in a cylinder tube,
In a fluid cylinder having a piston rod attached to the piston protruding from a cylinder tube, the piston and the piston rod are formed to be hollow, and a polygonal or spline-shaped guide rod fixed to an end of the cylinder tube is used as the piston. And a hollow guide member which is inserted into the hollow portion of the piston rod and is provided in the hollow portion of the piston or piston rod so as to be non-rotatably and slidably fitted to the guide rod. .