JP3474493B2 - Cylinder device - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to relates a stroke position of the piston arrangement the cylinder equipment to detect the magnetic sensor.

[0002]

2. Description of the Related Art Conventionally, in order to detect the stroke position of a piston of a fluid pressure cylinder, a ring-shaped permanent magnet made of synthetic resin is attached to the piston, and a magnetic sensor is attached to the outer peripheral surface of the cylinder tube. A device is used in which the magnetic sensor is operated by the magnetic field of the permanent magnet when the position of the magnetic sensor is reached.

In such a device, in order to mount the ring-shaped permanent magnet on the piston, it is necessary to divide the piston into two parts in the axial direction. Therefore, the structure of the piston becomes complicated, and the structure of the seal for preventing fluid leakage becomes complicated.

To solve this problem, it is possible to divide the ring-shaped permanent magnet in the circumferential direction without dividing the piston. However, in this case, after mounting the permanent magnet on the piston, it is necessary to fix the permanent magnet with an adhesive or a synthetic resin ring so that the permanent magnet does not fall off the piston.

[0005]

Since any of the above-mentioned devices uses a ring-shaped permanent magnet, it is necessary to manufacture permanent magnets of various sizes suitable for different diameters of the cylinder tube. Therefore, the die cost of the permanent magnet is high, which increases the manufacturing cost of the fluid pressure cylinder.

On the other hand, it has been proposed to prepare a plurality of small columnar permanent magnets and insert the permanent magnets into a lateral hole provided at a position close to the outer peripheral surface of the piston. However, in this case, since the permanent magnets are arranged at intervals and the magnetic force changes depending on the position in the circumferential direction, the magnetic sensor may not detect depending on the rotational angle position of the piston. There is a problem in.

The present invention has been made in view of the above-mentioned problems, and the permanent magnet can be used in common regardless of the diameter of the cylinder tube, whereby the manufacturing cost of the permanent magnet can be suppressed and the magnetic sensor can be used. It is an object of the present invention to provide a cylinder device and a magnetic field generator that can be reliably detected.

[0008]

According to a first aspect of the present invention, there is provided a magnetic sensor which responds to a magnetic field from a magnetic field generator mounted on the piston to determine the stroke position of the piston sliding in the cylinder tube. A cylinder device configured to detect, wherein the magnetic generation device comprises:
A permanent magnet member group consisting of a plurality of columnar permanent magnet members arranged along the circumference of the piston such that both magnetic poles are arranged along the axial direction of the piston and the magnetic poles face the same direction as each other; A generally annular magnetic ring arranged along the magnetic poles on both sides of the permanent magnet member group, and a resin ring arranged on the outer peripheral surface of the permanent magnet member group to fix the permanent magnet member group. Have and before
The magnetic ring is composed of a plurality of magnetic rings divided in the circumferential direction.
Each magnetic ring member is composed of
A protruding piece protruding toward the inner peripheral surface of the permanent magnet member group
And the magnetic generator is made of a non-magnetic material.
It is mounted in an annular groove on the outer peripheral surface of the piston.
Become.

[0009]

In the apparatus according to the second aspect of the present invention, the resin ring is made of a heat-shrinkable synthetic resin material, and the permanent magnet member group is fixed by heating and shrinking the resin ring. Become.

[0011]

[0012]

1 is a cross-sectional view showing a part of a fluid pressure cylinder 1 according to the present invention, and FIG. 2 is a view showing a part of the magnetic generator 3 taken along a plane including an axis. 3 is a cross-sectional view showing the piston of the fluid pressure cylinder 1 in a plane perpendicular to the axis, and FIG. 4 is a perspective view showing a schematic configuration of the magnetic field generator 3.

As shown in these drawings, the fluid pressure cylinder 1 is composed of a cylinder tube 11 made of a non-magnetic material, a piston 12 made of a non-magnetic material, a piston rod 13, and the like. The piston 12 is provided with a circular-cylindrical groove 21 substantially at the center of its outer peripheral surface.
A magnetic field generator 3 is mounted inside.

Packings 16 and 17 and a wear ring 18 are mounted on the piston 12, and are fixed to the piston rod 13 by a nut 19. A magnetic sensor 31 is attached to the outer peripheral surface of the cylinder tube 11 for magnetically responding to the magnetic field generated by the magnetic field generator 3 and for detecting the stroke position of the piston 12.

As shown in FIGS. 2 to 4, the magnetic generator 3 includes a plurality of permanent magnet members 41a, 41a ...
The permanent magnet member group 41 is composed of two magnetic rings 42, 43 and a resin ring 44, which are annular as a whole.

Each of the permanent magnet members 41a is formed of ferrite, other permanent magnet material, synthetic resin or the like in a cylindrical shape, and has both N and S poles arranged along the axial direction of the piston 12. Moreover, the magnetic poles are arranged so as to face the same direction. These permanent magnet members 41a
However, the permanent magnet member group 41 is configured by being arranged in a tubular shape as a whole.

Each of the magnetic rings 42 and 43 is made of a metal plate made of a magnetic material, and is formed in an annular shape as a whole. Each magnetic ring 42, 43 consists of two semi-circular magnetic ring members 42A, 42B, 43A, 43B.
That is, if the entire shape of each magnetic ring 42, 43 is divided into two in the circumferential direction, the magnetic ring members 42A, 42B, 43 are divided.
A and 43B.

Each magnetic ring member 42A, 42B, 43
A and 43B have a plurality of protruding pieces 42a and 43a, which project toward the inner peripheral surface of the permanent magnet member group 41 at their inner peripheral edges.
a is provided. These protruding pieces 42a and 43a are
The magnetic ring members 42A, 42B, 43A, and 43B are engaged with the inner peripheral surface of the permanent magnet member group 41 to prevent the magnetic ring members 42A, 42B, 43A, and 43B from popping out.

The protruding pieces 42a and 43a are preferably made of a non-magnetic material. The reason is that the protruding pieces 42a, 42
When 3a is a magnetic material, this weakens the magnetic poles generated between the magnetic rings 42 and 43. However, the lengths and widths of the projecting pieces 42a and 43a are reduced, and the projecting pieces 42a and 43a are arranged so as not to come close to each other, so that even a magnetic material is not affected so much. You can

These magnetic ring members 42A, 42B, 4
3A and 43B are arranged along the magnetic poles on both sides of the permanent magnet member group 41. Therefore, one magnetic ring member 4
One magnetic pole, for example, N pole is formed on the second magnetic pole 2, and the other magnetic pole, for example, S pole is formed on the other magnetic ring member 43.

The resin ring 44 is arranged on the outer periphery of the permanent magnet member group 41, and then heated and contracted to tightly adhere to the outer peripheral surface of the permanent magnet member group 41 so that each of the permanent magnet members 41a is attached. Fix it so that it does not fall off.

The resin ring 44 is a thin-walled tube (for example, GF tube RC manufactured by Gunze Co., Ltd.) having a heat-shrinking property made of a fluorine resin or the like, and a width of the outer peripheral surface of the permanent magnet member group 41 (in the axial direction). The outer diameter of the permanent magnet member group 41 is slightly larger than that of the permanent magnet member group 41 before contraction. But,
By being heated to about 80 to 200 degrees C, it contracts smaller than the outer diameter of the permanent magnet member group 41. For heating the resin ring 44, for example, a hair dryer or other hot air gun is used.

The outer diameter of the resin ring 44 after contraction is smaller than the inner diameter of the cylinder tube 11, so that sliding with the inner peripheral surface of the cylinder tube 11 does not occur.
However, even if sliding occurs between them, the resin ring 44 is made of fluorine resin having good slidability,
There is no problem with the operation of the piston 12.

According to the magnetic generator 3 described above, both magnetic poles of the permanent magnet member group 41 mainly appear on the outer peripheral edge and the inner peripheral edge of the magnetic rings 42 and 43. Then, the non-uniformity of the magnetic poles due to the permanent magnet member group 41 consisting of a plurality of permanent magnet members 41a discretely arranged is leveled by the presence of the magnetic rings 42 and 43, and the magnetic rings 42 and 43 are substantially uniform. A magnetic pole is created. As a result, on the outer peripheral surface of the cylinder tube 11, the magnetic field generated by the permanent magnet member group 41 becomes substantially uniform along the circumferential direction, and even when the piston 12 is at any rotation angle position, the magnetic sensor 31 is at any rotation angle position. Even when attached, the magnetic sensor 31 normally operates by detecting the magnetism of the magnetic generator 3. Therefore, the stroke position of the piston 12 is reliably detected.

According to the above-described magnetic generator 3, the common permanent magnet member 41a is used to form the permanent magnet member group 41, and the permanent magnet member group 41 having any diameter can be formed. In addition, the cylinder tube 11 having various diameters can be accommodated, and the manufacturing cost thereof is low. Since the magnetic rings 42 and 43 are present, the magnetic force in the circumferential direction is uniform, so that the detection by the magnetic sensor 31 is surely performed.

Further, since it is not necessary to divide the piston 12, the conventional problems due to the division are solved, the structure of the fluid pressure cylinder device 1 is simplified, the degree of freedom in design and reliability are increased, and the cost is reduced. Can be achieved.

In the above embodiment, the permanent magnet member 4
1a or permanent magnet member 41a and magnetic ring member 4
An adhesive may be applied to the joint surface between 2A, 42B, 43A and 43B or the contact surface between the magnetic rings 42 and 43 and the groove 21. Even in this case, since the minimum necessary amount of adhesive that does not stick out from the groove 21 may be used, an excessive adhesive removal work as in the case of using only the adhesive as in the conventional case is performed. No need.

Further, the magnetic rings 42 and 43 are each provided with 2
Although it is divided, it may be divided into three or more. Further, it may be an integral one that is not divided. The entire magnetic rings 42 and 43 may be integrally manufactured. The number of permanent magnet members 41a, the number and shape of the divided portions of the magnetic rings 42 and 43, the structure of the piston 12, and the like can be variously changed other than those described above.

The present invention is applicable to various fluid pressure cylinders other than the fluid pressure cylinder 1, a cylinder device which operates at other than fluid pressure,
It can be applied to other devices.

[0030]

According to the present invention, the permanent magnet can be used in common regardless of the bore of the cylinder tube, and the cost for manufacturing the permanent magnet can be suppressed. Moreover, the detection by the magnetic sensor can be reliably performed.

[Brief description of drawings]

FIG. 1 is a sectional view showing a part of a fluid pressure cylinder according to the present invention.

FIG. 2 is a view showing a part of the magnetic field generator, which is sectioned in a plane including an axis.

FIG. 3 is a cross-sectional view showing a piston of a fluid pressure cylinder in a plane perpendicular to the axis.

FIG. 4 is a perspective view showing a schematic configuration of a magnetic field generator.

[Explanation of symbols]

1 Fluid pressure cylinder (cylinder device) 3 Magnetic generator 11 cylinder tube 12 pistons 21 groove 41 Permanent magnet member group 41a Permanent magnet member 42,43 Magnetic ring 42A, 42B, 43A, 43B Magnetic ring member 42a, 43a protruding piece 44 resin ring 31 Magnetic sensor

Claims (2)

(57) [Claims] 1. A cylinder device configured to detect a stroke position of a piston sliding in a cylinder tube by a magnetic sensor which is mounted on the piston and which responds to a magnetic field from a magnetic generator. The generator is composed of a plurality of columnar permanent magnet members arranged along the circumference of the piston such that both magnetic poles are arranged along the axial direction of the piston and the magnetic poles face the same direction. A magnet member group, a generally annular magnetic ring arranged along the magnetic poles on both sides of the permanent magnet member group, and a resin which is arranged on the outer peripheral surface of the permanent magnet member group and fixes the permanent magnet member group. Ri Na a a ring, the magnetic ring is circumferentially divided the plurality of magnetic Li
Consist ring member, each magnetic ring member has at its inner periphery, said permanent magnet member
The piston having a projecting piece projecting toward the inner peripheral surface of the group, wherein the magnetic generator is made of a non-magnetic material.
A cylinder device, which is mounted in an annular groove provided on the outer peripheral surface of the cylinder device. Wherein said resin ring is made of synthetic resin material having a heat-shrinkable, by deflating by heating the resin ring, the formed by the permanent magnet member groups are fixed, No placement claim 1 Symbol Cylinder device.