JPH1114301A - Detection device and cylinder device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detection device which can use a cylinder tube made of a magnetic material and increase a range of a shape and a size of an available magnetic sensor, and in which a size of the gap can be optimally designed. SOLUTION: A detection device 15 is installed on a surface of a cylinder tube 11 made of a magnetic material and detects a magnetic field of a permanent magnet which moves along an inner periphery of the cylinder tube 11. Two magnetic bypass members 31 and 32 made of a material of high magnetic permeability are disposed along the direction of the both magnetic poles of the permanent magnet in such a way that each one end parts thereof are in proximity to or abuts on the cylinder tube 11 and each other end parts thereof are put opposite each other so as to have a clearance between them. A magnetic sensor 34 which detects the magnetic field is disposed at a position in proximity to the opposite part of the other end parts of the magnetic bypass members 31 and 32 in such a way that the position of the magnetic sensor 34 is overlapped with that of the magnetic bypass members 31 and 32 in the extending direction of the magnetic bypass members 31 and 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a detection device and a cylinder device using the same.

[0002]

2. Description of the Related Art Conventionally, a detecting device for detecting a magnetic field of a permanent magnet attached to a piston is used to detect a piston position of a cylinder device.

[0003] In the conventional detection device, it is necessary to use a non-magnetic material for the cylinder tube because the magnetic field of the permanent magnet provided on the piston needs to pass through the cylinder tube to the outside. For this reason, a steel material, which is a magnetic material, cannot be used for the cylinder tube, and the thickness and outer diameter of the cylinder tube are increased, resulting in a problem that the size of the cylinder device is increased.

[0004] Further, when the thickness of the cylinder tube is increased, the magnetic field emitted to the outside is weakened, so that there is a problem that the detection by the detection device becomes difficult. In order to solve these problems, a magnetic material is used for the cylinder tube, and two magnetic conductors made of a high magnetic permeability material are placed so that one end is close to the cylinder tube and between the other ends. A detection device has been proposed in which a magnetic sensor is mounted in a space between two magnetic conductors so as to form a space (Japanese Patent Publication No. 7-76682).

[0005]

However, according to the conventional sensing device described above, since the magnetic sensor is mounted in the gap between the two magnetic conductors, the size of the gap depends on the size of the magnetic sensor. .

[0006] Therefore, when the magnetic sensor is large, the gap becomes large, so that the shape and dimensions of the magnetic sensor that can be used are limited, and it is difficult to design the size of the gap to an optimum value. Also, the types of magnetic sensors that can be used are limited.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is possible to use a cylinder tube made of a magnetic material. It is an object of the present invention to provide a detection device capable of designing the size of an air gap to an optimum value and a cylinder device using the same.

[0008]

According to a first aspect of the present invention, there is provided an apparatus which is mounted on one surface of a wall member made of a magnetic material, and which controls a magnetic field of a magnet which moves along the other surface of the wall member. A sensing device for sensing, wherein two magnetic bypass members made of a high magnetic permeability material have one end close to or in contact with the wall member and the other end facing each other with a clearance. The magnetic bypass member is disposed along the direction of both magnetic poles of the magnet as a whole, at a position close to the periphery of the opposing portion at the other end of the magnetic bypass member, and at a position close to the magnetic bypass member in the direction in which the magnetic bypass member extends. The magnetic sensors for detecting the magnetic field are arranged so that they overlap.

According to a second aspect of the present invention, there is provided the magnetic bypass member, wherein one magnetic bypass member made of a material having a high magnetic permeability is arranged so that both ends thereof face the wall member, and the magnetic bypass member is located near the magnetic bypass member. A magnetic sensor for detecting a magnetic field is provided.

According to a third aspect of the present invention, there is provided a cylinder tube made of a magnetic material, a piston sliding in the cylinder tube, a permanent magnet provided on the piston,
And a detecting device attached to the outer surface of the cylinder tube for detecting the magnetic field of the permanent magnet, wherein the detecting device includes two magnetic bypass members made of a high magnetic permeability material, The other end of each of the magnetic bypass members is disposed as a whole along the direction of both magnetic poles of the permanent magnet so that one end is close to the cylinder tube and the other end is opposed to each other with a clearance. A magnetic sensor for detecting a magnetic field is disposed at a position near the opposing portion so as to overlap the magnetic bypass member in a direction in which the magnetic bypass member extends.

As the material of the magnetic bypass member, permalloy, silicon steel, iron cobalt alloy, iron nickel alloy, permalloy clad stainless steel, or the like is used. As the magnetic sensor, a Hall element, a Hall IC, a magnetoresistive element (MR element), a magnetic transistor, a reed switch, a proximity sensor, a coil, and the like are used.

[0012]

1 is a sectional view showing a main part of a cylinder device 1 according to the present invention, FIG. 2 is a sectional front view of a detecting device 15, FIG. 3 is a sectional plan view of the detecting device 15, and FIG. FIG. 3 is a sectional side view of the detection device 15.

In FIG. 1, a cylinder device 1 includes a cylinder tube 11, a piston 12, a piston rod 13,
It comprises a permanent magnet 14, a detection device 15, a cylinder cover (not shown), and the like.

The cylinder tube 11 is made of a magnetic material such as carbon steel pipe. The piston 12 is made of a non-magnetic material such as an aluminum alloy or stainless steel, and has a permanent magnet 14 mounted in an annular groove provided on the outer periphery.
The piston 12 is provided with a packing (not shown) for sealing between the piston 12 and the cylinder tube 11. The piston rod 13 is made of a steel material or the like, and is integrally connected to the piston 12 by a screw or the like provided at a distal end thereof.

The permanent magnet 14 is annular and has an N pole and an S pole in a direction along the axial direction of the piston rod 13. The detection device 15 detects the magnetic field of the permanent magnet 14 and thereby detects the position of the piston 12.

Referring also to FIG. 2 and FIG.
A casing 30, magnetic bypass members 31, 32, a coupling member 33, a magnetic sensor 34, a support plate 35, a substrate 36,
And a cable 37.

The casing 30 is made of a synthetic resin or the like, and accommodates components such as the magnetic bypass members 31 and 32 therein. The magnetic bypass members 31 and 32 are made of a material having high magnetic permeability, and are formed in a substantially L-shape. Each of the magnetic bypass members 31 and 32 is formed such that one end portions 311 and 321 are formed to be wide and the outer end surfaces thereof are arranged close to the cylinder tube 11, preferably in a state of being in contact with the cylinder tube 11. It is exposed on the same surface as the outer surface of the casing 30. Therefore, the shape of the outer end surfaces of the end portions 311 and 321 may be a flat surface, but is preferably a curved surface along the peripheral surface of the cylinder tube 11.
The other end portions 312 and 322 of the magnetic bypass members 31 and 32
Are provided facing each other with a clearance GP, and a coupling member 33 made of an adhesive or the like applied therebetween is provided. The size of the clearance GP is, for example, 0.1 to
It is about 0.5 mm. The coupling member 33 is, of course, a non-magnetic material. The magnetic bypass members 31 and 32 are arranged along the directions of both magnetic poles of the permanent magnet 14 as a whole.

As the material of the magnetic bypass members 31 and 32, for example, permalloy, silicon steel, iron-cobalt alloy,
Iron-nickel alloy, permalloy clad stainless steel or the like is used. These materials are used for magnetic shields and magnetic head cores, and have a maximum relative permeability of 1
0000 or more. It also has a low coercive force and is therefore a soft magnetic material. Also, the magnetic bypass member 31,
The material used for 32 has a smaller saturation magnetic flux density than the material of the cylinder tube 11.

As the magnetic sensor 34, a Hall element, a Hall IC, a magnetoresistive element (MR element), a magnetic transistor, a reed switch, a proximity sensor, and the like are used.
The position where the magnetic sensor 34 is disposed is a position near the coupling member 33 and a position where the position overlaps with the magnetic bypass members 31 and 32 in the direction in which the magnetic bypass members 31 and 32 extend. In the example shown in the figure, the magnetic sensor 34 is disposed above the magnetic bypass members 31 and 32 and the center of the magnetic sensor 34 is located directly above the coupling member 33. It is preferable that the portion of the magnetic sensor 34 that senses magnetism be located between the other end portions 312 and 322.

As described above, since the magnetic sensor 34 is disposed around the magnetic bypass members 31 and 32, the size of the clearance GP of the facing portion of the magnetic bypass members 31 and 32 depends on the size of the magnetic sensor 34. Without having to
The size of the clearance GP can be designed to an optimum value. In addition, since the degree of freedom in the position of the magnetic sensor 34 is high, the magnetic sensors 34 having various shapes and dimensions can be arranged at appropriate positions, and the optimum design of the detection device 15 can be performed.

A substrate 36 is mounted on one surface of the support plate 35, and magnetic bypass members 31, 32 are mounted on the other surface. A circuit pattern for performing the function of the detection device 15 is provided on the substrate 36, and a power supply circuit, an amplification circuit, an output circuit,
A display circuit and a magnetic sensor 34 are mounted. The magnetic sensor 34 is held by a substrate 36.

The cable 37 is for supplying power to the substrate 36, extracting an output signal based on the operation of the magnetic sensor 34, and the like. Usually, when power supply and output are commonly performed, If two wires are used separately, three wires are used.

Next, the operation of the above-described cylinder device 1 will be described. In FIG. 1, most of the magnetic lines of force coming out of the N pole of the permanent magnet 14
Return to the pole. Part of the lines of magnetic force that have entered the cylinder tube 11 enter the magnetic bypass member 31 from one end 311, pass through the magnetic bypass member 31 and the magnetic bypass member 32, and return to the cylinder tube 11 from the one end 321. In the opposing portions of the magnetic bypass members 31 and 32, a part of the magnetic force lines pass through the coupling member 33 and the other part passes through the magnetic sensor 34.

The relative magnetic permeability of the magnetic bypass members 31 and 32 is 10,000 or more, and the relative magnetic permeability of the cylinder tube 11 is about several hundreds.
The magnetic permeability is several orders of magnitude or more, which is several orders of magnitude higher than that of the cylinder tube 11, and most of the lines of magnetic force near the one end 311 flow into the magnetic bypass member 31. That is, the magnetic bypass members 31 and 32 have a function of bypassing the lines of magnetic force flowing through the cylinder tube 11.

The lines of magnetic force flowing into the magnetic bypass member 31 are supplied to the magnetic bypass member 3 near the coupling member 33.
Since the light passes through the outside of the first and the second 32, it is detected by the magnetic sensor 34 arranged around the outside.

When the number of lines of magnetic force passing through the magnetic sensor 34, that is, the strength of the magnetic field, exceeds a certain value, the detecting device 15
Outputs a detection signal and turns on the display element of the display circuit. The detection signal is a switching signal for turning on an external load. However, the detection signal may be a signal corresponding to the strength of the detected magnetic field.

According to the cylinder device 1, a carbon steel tube can be used as the material of the cylinder tube 11, so that the thickness of the cylinder tube 11 can be reduced, the outer diameter can be reduced, and the entire cylinder device 1 can be reduced. Can be reduced in size. Further, since the thickness of the cylinder tube 11 is reduced, the material cost can be reduced and the weight can be reduced.

Moreover, magnetic sensors 34 of various shapes and sizes
Can be arranged at an appropriate position, and the clearance GP can be set to an optimal value.

In the above embodiment, the magnetic bypass members 31, 32 have a rectangular cross section, but may have a square shape. Further, the shape may be a circle, an ellipse, a triangle, a pentagon, or the like.

Next, another example of the shape of the other end portions 312 and 322 of the magnetic bypass members 31 and 32 will be described. FIG. 5 is a diagram showing another example of the shape of the other end of the magnetic bypass member.

The magnetic bypass member 31 shown in FIG.
At A and 32A, the other end portions 312A and 322A are tapered, so that the lines of magnetic force gather toward the magnetic sensor 34A.

The magnetic bypass member 31 shown in FIG.
B and 32B, the other end portions 312B and 322B are thinner than the other portions, and the magnetic force lines are also
They come to B.

Next, another example of the detection device will be described. FIG. 6 is a diagram illustrating another example of the detection device 15C. In the detecting device 15 of FIG. 1, two magnetic bypass members 31 and 3 are provided.
2 is provided, whereas the detection device 15C of FIG.
In the example, one magnetic bypass member 41 is provided.
The magnetic sensor 34 </ b> C is a coil wound around the magnetic bypass member 41 to detect a change in the line of magnetic force passing through the magnetic bypass member 41. That is, the number of lines of magnetic force passing through the magnetic bypass member 41 changes with the movement of the piston 12, so that the magnetic sensor 34C
, An induced current is induced.

In the detection device 15C, the magnetic sensor 34
, And outputs a detection signal when the induced current exceeds a predetermined value. FIG. 7 is a diagram illustrating a detection device 15D of still another example.

In this detection device 15D, one magnetic bypass member 42 is provided. Magnetic sensor 34
D reads and outputs lines of magnetic force flowing through the magnetic bypass member 42. The detection device 15D includes a magnetic sensor 34D
, And outputs a detection signal when the output exceeds a predetermined value. The relative permeability and dimensions of the cylinder tube 11 and the magnetic bypass member 42 are determined by the magnetic sensor 34.
D is selected so that the detection output by D is as large as possible.

In the above embodiment, the shape, material, size and number of the permanent magnets 14 can be various. It is also possible to use electromagnets instead of permanent magnets. One cylinder device 1 has a plurality of detection devices 15, 1
5C and 15D can be attached. Detection device 1
5, 15C, 15D and the structure and shape of the cylinder device 1,
The dimensions and the like can be appropriately changed according to the gist of the present invention.

The detection device of the present invention can be applied to various devices other than the cylinder device 1, for example, detection of a floating position in a tank made of a magnetic material.

[0038]

According to the present invention, it is possible to use a cylinder tube made of a magnetic material, furthermore, it is possible to widen the range of the shape and dimensions of a usable magnetic sensor, and to optimize the size of the air gap. Can be designed.

According to the third aspect of the present invention, a small and lightweight cylinder device capable of detecting the position of the piston can be obtained.

[Brief description of the drawings]

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

FIG. 2 is a sectional front view of the detection device.

FIG. 3 is a cross-sectional plan view of the detection device.

FIG. 4 is a cross-sectional side view of the detection device.

FIG. 5 is a view showing another example of the shape of the other end of the magnetic bypass member.

FIG. 6 is a diagram illustrating another example of a detection device.

FIG. 7 is a diagram illustrating another example of a detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder apparatus 11 Cylinder tube (wall member) 12 Piston 14 Permanent magnet (magnet) 15 Detector 15C, 15D Detector 31, 32 Magnetic bypass member 31A, 32A Magnetic bypass member 31B, 32B Magnetic bypass member 311, 321 One end ( One end) 312, 322 The other end (the other end) 34 Magnetic sensor 34A, 34B, 34C, 34D Magnetic sensor

Claims (3)

[Claims] 1. A detecting device for detecting a magnetic field of a magnet attached to one surface of a wall member made of a magnetic material and moving along the other surface of the wall member, comprising: a material having a high magnetic permeability; Two magnetic bypass members, each having one end close to or in contact with the wall member and the other end facing each other with a clearance,
As a whole, the magnetic bypass member is disposed along the directions of both magnetic poles of the magnet, and the position overlaps with the magnetic bypass member in a direction in which the magnetic bypass member extends in a proximity position around the opposing portion at the other end of the magnetic bypass member. And a magnetic sensor for detecting a magnetic field. 2. A detecting device for detecting a magnetic field of a magnet attached to one surface of a wall member made of a magnetic material and moving along the other surface of the wall member, the device comprising a high-permeability material. And a magnetic sensor for detecting a magnetic field is arranged at a position near the magnetic bypass member, the magnetic sensor being located near the wall member. Detection device. 3. A cylinder tube made of a magnetic material, a piston sliding in the cylinder tube, a permanent magnet provided on the piston, and a magnetic field of the permanent magnet attached to an outer surface of the cylinder tube. A detecting device for detecting, wherein the detecting device comprises two magnetic bypass members made of a high magnetic permeability material, one end of each of which is close to the cylinder tube and the other end of which has a clearance. The magnetic bypass member is disposed along the direction of both magnetic poles of the permanent magnet as a whole so as to face each other, and at a position close to a periphery of a facing portion at each other end of the magnetic bypass member, in a direction in which the magnetic bypass member extends. A magnetic sensor for detecting a magnetic field is disposed so as to overlap the position of the magnetic bypass member. Apparatus.