JP2003247861A - Linear sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a resolver type linear sensor by fitting magnetic boards to the plane portions of a rod made of a nonmagnetic material, and using these magnetic boards and coils. <P>SOLUTION: In this linear sensor, the magnetic boards (31) are fitted to the plane portions (30) of the rod (1) made of a nonmagnetic material, and a linear displacement is detected by detecting a change in the degree of magnetic coupling caused by relative movement between the magnetic boards (31) and the coils (14, 15). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear sensor, and in particular, a magnetic portion provided on a rod is attached to a flat portion as a preformed magnetic plate to improve the level of an output signal and facilitate mass production. Regarding new improvements in.

[0002]

2. Description of the Related Art As a linear sensor of this type which has been conventionally used, for example, there is a structure disclosed in Japanese Patent Publication No. 5-38247, and the structure of the rod is as shown in FIG. is there. That is, the reference numeral 1 in FIG. 13 is a rod made of an iron-based magnetic material in the shape of a round bar, and the peripheral surface 1 a of the rod 1 has a thickness of about 50 mm.
A magnetic portion 2 made of copper plating of about μm is provided in the groove 3, and a hard chrome plating 3 is formed on the surface of the magnetic portion 2. The manufacturing process of the rod 1 described above is as shown in FIG. 14, and the plating process was indispensable for manufacturing the rod 1.

[0003]

Since the conventional linear sensor is constructed as described above, the following problems exist. In other words, the outer circumference of the rod of magnetic material is plated with copper, and it must be removed except to leave this copper plating as the magnetic part that requires it. In addition, it is necessary to plate the entire rod with hard chrome, and since the number of times of plating is plural, the manufacturing process becomes complicated and it is difficult to reduce the cost. Further, in the case of the above-mentioned conventional example, since the change in the amount of current due to the eddy current using the exposed conductive portion of the rod is output by the output coil, the signal level of the output signal is low and a highly sensitive linear sensor Was difficult to obtain.

The present invention has been made to solve the above problems, and in particular, the magnetic portion provided on the rod is attached to the flat portion as a preformed magnetic plate to improve the level of the output signal. An object is to provide a linear sensor that facilitates mass production.

[0005]

According to the linear sensor of the present invention, a rod having a plurality of magnetic portions at a predetermined interval is provided in a cylindrical case having an exciting coil and an output coil relative to each coil. In a linear sensor arranged so as to be linearly displaceable so that the linear displacement of the rod is output from the output coil, the rod is made of a non-magnetic material and has a plurality of plane portions on its peripheral surface, The part is provided with a preformed magnetic plate for forming the magnetic part, and the planar part is at least two or more on the circumferential surface at the same position in the axial direction of the rod. The magnetic plates are provided on the same plane, and the magnetic plates are attached to each other with an anaerobic adhesive. And In addition, the magnetic plate is a structure that is covered with a resin provided in a cutout portion that forms the flat surface portion, and the magnetic plate is a structure that is fixed to the flat surface portion by welding, The excitation coil has one phase and the output coil has two phases, which is a one-phase excitation two-phase output type.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of a linear sensor according to the present invention will be described below with reference to the drawings. still,
The same or equivalent portions as those of the conventional example will be described using the same reference numerals. A reference numeral 1 in FIG. 1 denotes a tubular case (or it may be an incorporated portion in the apparatus), and a tubular magnetic shield member 12 having an end plate 11 is provided in the tubular case 10. It is provided.

An exciting coil 14 and an output coil 15 held by a resin bobbin 13 are provided in the magnetic shield member 12, and as shown in FIG.
A linear sensor composed of a linear resolver with one-phase excitation and two-phase output is formed. The magnetic shield member 12 is provided so that magnetic flux leakage from the coils 14 and 15 to the outside does not occur.

Each coil 14, 15 of the cylindrical case 10
Inside, the non-magnetic material such as stainless steel (weak magnetic is also acceptable)
Each coil 1 is a rod 1 formed of a long rod member formed by
It is inserted and arranged so as to be linearly displaceable relative to Nos. 4 and 15. On the peripheral surface 1a of the rod 1, a flat plane portion 3 having a notch formed along the tangential direction is formed.
0 is formed, and a flat plate-shaped magnetic plate 2 made of a magnetic material prepared in advance and prepared as a magnetic part is formed on the flat surface 30.
Are fixed by adhesion or the like.

The electromagnetic relationship between the exciting coil 14, the rod 1 and the output coil 15 is as shown in FIG. 2, and the magnetic plate 2 of the rod 1 is the same as in the well-known rotary resolver.
By changing the degree of magnetic coupling via, the two-phase output signal 31 of the sin phase and the cos phase shown in FIG. 3 is obtained according to the linear displacement of the rod 1.
The two-phase output signal 31 is a well-known signal conversion unit R /
The digital position signal 33 is converted and output via the D section 32.

The structure of the rod 1 is not limited to the structure shown in FIG. 1. For example, as shown in FIGS. 4 and 5, not only one rod but two rods (two or more rods are possible) on the flat portion 30. The magnetic plates 2 are laminated, and the dimensions of the magnetic plates 2 are such that the first width W ₁ in the axial direction matches the axial length of the flat portion 30, and the second width W ₂ in the cross-sectional direction is the rod. It is provided to be smaller than the diameter of 1. The plate thickness of the magnetic plate 30 is, as an example, as shown in FIG.
5 mm is preferred. Further, by increasing the number of the magnetic plates 30, the magnetic path is widened, the degree of magnetic coupling is improved, and the voltage level of the two-phase output signal 31 can be improved. Further, in FIGS. 4 and 5, the rod 1
The outer peripheral surface 1a of the magnetic plate 31 is formed on the outer peripheral surface 1a of the magnetic disk 31 at the same position in the axial direction so as to face each other by 180 °.
Although it is provided in two locations, it is not limited to these two locations, and it is also possible to have four locations, six locations, eight locations, etc.
An improvement in the voltage level of the phase output signal 31 can be obtained.

Further, when two magnetic plates 31 are laminated, if the joint portion with the rod 1 is adhered with a well-known anaerobic adhesive 40 as shown in FIG. 7, it is iron-based. Therefore, it is effective.

Further, the method of fixing the magnetic plate 31 to the rod 1 is not limited to the above-mentioned method. For example, as shown in FIGS. 8 and 9, a resin 50 made of epoxy resin or the like is dropped by a potting process. The magnetic plates 31 that have been subjected to the adhesion treatment can be fixed to the rod 1 while preventing the peeling due to the double adhesion of the adhesive and the resin. Also,
The outer diameter can be made the same as that of the rod 1, and the magnetic properties do not deteriorate. When the rod 1 is hollow, the wall thickness is thin, which is more effective.

Further, as shown in FIGS. 10 and 11, the magnetic plate 31 is directly welded to the rod 1 by welding 60, whereby the magnetic plate 31 can be mechanically most firmly fixed.

[0014]

Since the linear sensor according to the present invention is constructed as described above, the following effects can be obtained. That is, since the magnetic plate is provided on the flat plane part of the peripheral surface of the rod made of non-magnetic material, the output change due to the change in the degree of magnetic coupling between the magnetic plate and the coil (conventional) compared to the conventional eddy current change configuration. Since the linear position change is detected by the same principle as the resolver of (1), the voltage level of the output signal is higher than before and the rod can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing a linear sensor according to the present invention.

FIG. 2 is a principle diagram of the linear sensor of FIG.

FIG. 3 is an output waveform diagram of the output coil of FIG.

FIG. 4 is an overall configuration diagram of the linear sensor of FIG.

5 is a cross-sectional view of the rod of FIG.

6 is a cross-sectional view taken along the line AA of FIG.

FIG. 7 is an explanatory view of the magnetic plate of FIG.

FIG. 8 is an enlarged view of a main part of FIG.

9 is a cross-sectional view showing another form of FIG.

10 is a vertical cross-sectional view of FIG.

11 is a cross-sectional view showing another form of FIG.

12 is a vertical cross-sectional view of FIG.

FIG. 13 is a structural view with a partial cross section showing a conventional rod.

FIG. 14 is a manufacturing process diagram of the rod of FIG. 13;

[Explanation of symbols]

1 rod 10 cases 14 Excitation coil 15 Output coil 30 Plane 31 Magnetic plate (magnetic part) 50 Flat part (notch part)

Claims (7)

[Claims] 1. A rod (1) having a plurality of magnetic parts at predetermined intervals is provided in a cylindrical case (10) having an exciting coil (14) and an output coil (15), and each coil (14, 15) is provided with the rod (1). In the linear sensor which is arranged so as to be linearly displaceable relative to each other, and the linear displacement of the rod (1) is output from the output coil (15), the rod (1) is made of a non-magnetic material. In addition, it has a plurality of flat portions (30) on its peripheral surface, and the flat portion (30) is provided with a preformed magnetic plate (31) for constituting the magnetic portion. And a linear sensor. 2. The linear sensor according to claim 1, wherein at least two flat portions (30) are provided on the circumferential surface at the same position in the axial direction of the rod (1). 3. The magnetic plate (31) is provided in a plurality of layers on the same flat surface portion (30).
Alternatively, the linear sensor described in 2. 4. The linear sensor according to claim 3, wherein each of the magnetic plates (31) is adhered with an anaerobic adhesive. 5. The magnetic plate (31) is covered with a resin (50) provided in a cutout portion forming the flat surface portion (30), according to any one of claims 1 to 4. Linear sensor described in. 6. The linear sensor according to claim 1, wherein the magnetic plate (31) is fixed to the flat portion (30) by welding. 7. The excitation coil (14) is of one phase and the output coil (15) is of two phases to form a one-phase excitation two-phase output type. The linear sensor according to any of the above.