JPH11132204A - Cylinder device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide strong magnetic force, and cope with bores of cylinder tubes even variously different in bore size by permanent magnets of the same shape. SOLUTION: The cylinder device 1 is constituted so that a piston 12 slides in the inner circumferential face of a cylinder tube, and the piston 12 is composed of at least three members of an intermediate piston member 31, a first piston member 32 and a second piston member 33 that are arranged on both sides of the intermediate piston member 31, then the intermediate piston member 31 has a holding member 311 which is made of a nonmagnetic material and in which plural holes 311b are formed in the axial direction, and plural permanent magnets 312 which are fitted into the respective holes 311b so that the poles are arranged along the axial direction and the same poles are positioned on the same sides.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder device equipped with a permanent magnet for detecting a piston position.

[0002]

2. Description of the Related Art Conventionally, in order to detect a piston position of a hydraulic cylinder device, a permanent magnet is mounted on the piston,
2. Description of the Related Art A detection switch having a built-in magnetic sensor is arranged on an outer peripheral surface of a cylinder tube.

[0003] Various structures have been proposed for a piston on which a permanent magnet is mounted, but there are roughly the following two structures. One is a structure in which an annular groove is provided on the outer peripheral surface of a piston, and a ring-shaped permanent magnet is fitted into the groove.

[0004] The other is to move the piston along the axial direction.
In this structure, the piston is divided into two piston members, and a disk-shaped permanent magnet is sandwiched between them.

[0005]

According to the former, a relatively small permanent magnet can be easily manufactured, but it is difficult to obtain a strong magnetic force. Further, it is necessary to manufacture a permanent magnet having an outer diameter corresponding to the diameter (inner diameter) of the cylinder tube, and therefore, a large number of dies are required.

According to the latter, a strong magnetic force can be obtained, but it is necessary to manufacture a permanent magnet having an outer diameter corresponding to the diameter of the cylinder tube, which requires a large number of dies. In particular, if the outer diameter is larger than a certain dimension, it becomes impossible to integrally mold the permanent magnet. Therefore, the permanent magnet must be manufactured by cutting a disk-shaped member, which is expensive and unsuitable for mass production. It is.

[0007] The present invention has been made in view of the above-mentioned problems, and it is possible to obtain a strong magnetic force, and it is possible to use a permanent magnet having the same shape even when the cylinder tube has various diameters. It is an object of the present invention to provide a low-cost cylinder device.

[0008]

The device according to the present invention is a cylinder device 1 in which a piston 12 slides on an inner peripheral surface of a cylinder tube 11, wherein the piston 12 comprises: At least three of the intermediate piston member 31, and the first piston member 32 and the second piston member 33 arranged on both sides of the intermediate piston member 31.
The intermediate piston member 31 is made of a non-magnetic material, and the holding member 311 provided with a plurality of holes 311 b in the axial direction is provided with magnetic poles along the axial direction and is the same on the same side as each other. A plurality of permanent magnets 312 provided to fit into the holes 311b so as to have magnetic poles
And

In the device according to the second aspect of the present invention, the piston 12 includes at least two members: an intermediate piston member 31 and a first piston member 32 disposed on one side of the intermediate piston member 31. The intermediate piston member 31 includes a holding member provided with a plurality of axial holes formed of a non-magnetic material and not penetrating, and magnetic poles arranged along the axial direction and having the same magnetic pole on the same side as each other. And a plurality of permanent magnets 312 provided to be fitted into the respective holes, and the first piston member 32 is provided on the side where the end face of the permanent magnet 312 fitted to the holes is exposed, It is arranged so as to cover the end face.

[0010] In the device according to the third aspect of the present invention, the plurality of permanent magnets 312 are cylindrical and have the same size as each other. In the apparatus according to a fourth aspect of the present invention, the first piston member 32 and the second piston member 33 are provided with packings 321 and 331 for sealing between the first piston member 32 and the inner peripheral surface of the cylinder tube 11, respectively. Become.

The permanent magnet 312 is formed in a columnar shape, a prismatic shape, or another shape. The hole 311b has substantially the same shape as the permanent magnet 312.
Is inserted. The hole 311b may pass through the intermediate piston member 31 in the axial direction. When the hole 311b is penetrating, the first piston member 32 and the second piston member 33 are arranged on both sides of the intermediate piston member 31 in many cases. If the hole 311b does not penetrate, the hole 311b
The first piston member 32 is disposed on the side provided with 11b.

The intermediate piston member 31 is provided with holes 311b arranged substantially evenly along the circumferential direction. It is also possible to fix the permanent magnet 312 in the hole 311b with an adhesive.

The intermediate piston member 31, the first piston member 32, and the second piston member 33 are assembled by, for example, passing the piston rod 13 through a hole provided at the center thereof and tightening a nut or the like.

[0014]

1 is a sectional view of a hydraulic cylinder device 1 according to the present invention, and FIG. 2 is an exploded perspective view showing the structure of a piston 12 of the hydraulic cylinder device 1. FIG.

In these figures, the hydraulic cylinder device 1 comprises a cylinder tube 11, a piston 12, a piston rod 13, covers 14, 15, a bush 16, and detection switches 17, 18, and the like.

The cylinder tube 11 has a cylindrical shape made of a nonmagnetic material such as an aluminum alloy, a copper alloy, a zinc alloy, stainless steel, or a synthetic resin. The piston 12 slides on the inner peripheral surface of the cylinder tube 11. The piston 12 includes an intermediate piston member 31, a first piston member 32, and a second piston member 33.

The intermediate piston member 31 includes a disk-shaped holding member 311 made of a non-magnetic material, and a plurality of columnar permanent magnets 312, 312. A hole 311a through which the piston rod 13 penetrates is provided at the center of the holding member 311 and a plurality of holes 311b and 31 which penetrate in the axial direction are provided at the periphery thereof.
1b are provided respectively.

The permanent magnet 312 is made of carbon steel, cobalt steel,
It is formed in a cylindrical shape using alnico, synthetic rubber, or another material, and is magnetized along the axial direction. The permanent magnets 312 are provided by being fitted in the holes 311b of the holding member 311 such that the magnetic poles are arranged along the axial direction and have the same magnetic poles on the same side. Thereby, an N pole and an S pole are formed along the axial direction of the intermediate piston member 31.

It is desirable that the permanent magnet 312 does not move in the hole 311b when assembled as the piston 12. Therefore, the outer dimensions of the permanent magnet 312 and the inner diameter of the hole 311b or the width (thickness) of the holding member 311 have a relationship such that the permanent magnet 312 does not rattle in the hole 311b. However, for example, hole 311
The inner diameter of b may be slightly larger than the outer diameter of the permanent magnet 312, and an adhesive may be used to fix or temporarily fix the permanent magnet 312 in the hole 311b.

Since the plurality of permanent magnets 312 are simple and small in shape, and are all the same, a magnet having a strong magnetic force can be easily manufactured and the cost is low. First
The piston member 32 is a disk-shaped member made of a non-magnetic material. The center portion has a hole through which the piston rod 13 penetrates, the outer peripheral surface has a concave groove, and the packing 3 for sealing between the cylinder tube 13 and the inner peripheral surface.
21 are mounted.

The second piston member 33 is a disk-shaped member made of a non-magnetic material. A hole through which the piston rod 13 penetrates is provided at the center, a concave groove is provided on the outer peripheral surface, and a packing 331 for sealing between the cylinder tube 13 and the inner peripheral surface is mounted. The first piston member 32 and the second piston member 33 can have the same shape. In that case, the cost can be reduced by mass production.

The intermediate piston member 31, the first piston member 32, and the second piston member 33 have the intermediate piston member 31 disposed at the center, and the first piston member 32 and the second piston member 33 disposed on both sides thereof. The small diameter portion of the piston rod 13 penetrates the hole at the center, and is assembled by tightening with a nut 13a. As a result, N
A magnetic field is formed from the pole to the south pole.

The piston rod 13 protrudes outside through a bush 16 provided on the cover 14. Cover 1
Ports 21 and 22 are provided in 4 and 15, respectively. The detection switches 17 and 18 arranged on the outer peripheral surface of the cylinder tube 11 operate in response to the magnetic field generated by the permanent magnet 312 according to the stroke position of the piston 12.

According to the fluid pressure cylinder device 1 of the above-described embodiment, each of the permanent magnets 312 can be made strong, and a large number of permanent magnets 312 are mounted on one intermediate piston member 31. Magnetic force can be obtained. In addition, even when the diameter of the cylinder tube 11 is variously different, the permanent magnets 312 having the same shape can be used, so that one type of the permanent magnet 312 can be used for the fluid pressure cylinder device 1 having all the diameters. Therefore, only one type of mold is required for manufacturing the permanent magnet 312, and mass production can be performed, so that significant cost reduction can be achieved. In particular, even a large-diameter hydraulic cylinder device does not become particularly expensive. Note that the number of permanent magnets 312 may be increased or decreased according to the aperture.

FIG. 3 is a front view showing a modification of the intermediate piston member. The intermediate piston member 31B shown in FIG.
Here, the permanent magnets 312 are arranged on each circumference of the double circle. The intermediate piston member 31 shown in FIG.
C, a hole 311Cb provided in the holding member 311C.
However, therefore, the permanent magnet 312 is exposed on the outer peripheral surface of the holding member 311C. According to these structures, the magnetic field to the detection switches 17 and 18 becomes stronger.

FIG. 4 is a diagram showing a cross section of a main part of a piston 12D according to another embodiment. In FIG. 4, the piston 12
D includes an intermediate piston member 31D and a first piston member 32D made of a non-magnetic material. The intermediate piston member 31D has a plurality of axial holes 311D that do not penetrate.
and a permanent magnet 312 fitted in each hole 311Db. The first piston member 32D is disposed so as to cover the end surface of the permanent magnet 312 on the side where the end surface is exposed.

In the piston 12D of this embodiment, the structure of the piston 12D is simpler. Since there is the first piston member 32D, the permanent magnet 3 fitted in the hole 311Db
12 does not come out during use.

In the above embodiment, a non-magnetic material is used for the first piston member 32 and the second piston member 33. However, a magnetic material is used, and the N and S poles of the permanent magnet 312 are changed to the first piston member 32. Outer peripheral surface of the second piston member 33
May appear on the outer peripheral surface. In this case, the small diameter portion of the piston rod 13 is preferably made of a non-magnetic material. Further, the first piston member 32 and the second piston member 33 are made of a non-magnetic material, and a disk made of a magnetic material is sandwiched between the intermediate piston member 31 and the first piston member 32 and the second piston member 33, respectively. Good. In this case, it is preferable that the inner diameter of the disc is larger than the outer diameter of the small diameter portion of the piston rod 13 so as not to short-circuit magnetically. Although a non-magnetic material is used for the cylinder tube 11, it is also possible to use a magnetic material.

In the above embodiment, the holding member 311
Are penetrated in the axial direction, but may be holes that do not penetrate. For example, one side surface of the holding member 311 may be a flat surface, and the permanent magnet 312 may be inserted into the hole from the other side surface. The permanent magnet 312 has a columnar shape, but may have a prismatic shape. In addition, the structure, shape, size, number, material, and the like of the whole or each part of the fluid pressure cylinder device 1 can be appropriately changed other than those described above in accordance with the gist of the invention.

The present invention can be applied to accumulators, spool valves, and various other cylinder devices in addition to the hydraulic cylinder device.

[0031]

According to the present invention, a strong magnetic force can be obtained, and even if the diameter of the cylinder tube is variously varied, it is possible to cope with a permanent magnet having the same shape. Can be planned.

According to the third aspect of the present invention, only one type of mold is required for manufacturing the permanent magnet, and mass production can be performed, so that a significant cost reduction can be achieved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a hydraulic cylinder device according to the present invention.

FIG. 2 is an exploded perspective view showing a structure of a piston of the fluid pressure cylinder device.

FIG. 3 is a front view showing a modification of the intermediate piston member.

FIG. 4 is a view showing a cross section of a main part of a piston according to another embodiment.

[Explanation of symbols]

 Reference Signs List 1 fluid pressure cylinder device (cylinder device) 11 cylinder tube 12 piston 31, 31B, 31C, 31D intermediate piston member 32, 32D first piston member 33 second piston member 311, 311B, 311C, 311D holding member 311b, 311Bb, 311Cb , 311Db hole 312 permanent magnet 321 331 packing

Claims (4)

[Claims] 1. A cylinder device in which a piston slides on an inner peripheral surface of a cylinder tube, wherein the piston has an intermediate piston member and first pistons arranged on both sides of the intermediate piston member. A piston member and a second piston member, at least three members, wherein the intermediate piston member is made of a non-magnetic material and provided with a plurality of axial holes, and a magnetic pole along the axial direction. And a plurality of permanent magnets arranged and fitted in the holes so as to have the same magnetic pole on the same side as each other. 2. A cylinder device, wherein a piston is configured to slide on an inner peripheral surface of a cylinder tube, wherein the piston is an intermediate piston member and a second piston member disposed on one side of the intermediate piston member. Of one piston member,
The intermediate piston member is made of a non-magnetic material and has a plurality of axially provided holes that are not penetrated, and a magnetic pole is arranged along the axial direction and on the same side with each other. A plurality of permanent magnets provided in the respective holes so as to have the same magnetic pole, and wherein the first piston member is provided on the side where an end face of the permanent magnet fitted in the holes is exposed. A cylinder device arranged so as to cover an end surface of the cylinder device. 3. The cylinder device according to claim 1, wherein the plurality of permanent magnets are cylindrical and have the same size as each other. 4. The cylinder device according to claim 1, wherein the first piston member and the second piston member are each provided with a packing for sealing between the first piston member and the inner peripheral surface of the cylinder tube.