JPH0434312A - Position detector - Google Patents

Abstract

PURPOSE:To enable highly accurate and stable detection of a position by moving a moving object with a magnetic detector on to a rail with a magnetic flux density varying in a direction of moving to determine the position of the moving object with increase or decrease in the magnetic flux density detected by the magnetic detector. CONSTITUTION:A position detector is made up of a rail constituted of an upper magnet section 1 and a lower magnet section 2 and a moving member 3 having a Hall element 30 for magnetic detection inside being sandwiched therebetween. The magnet section 2 is so arranged that the top surface of a permanent magnet part 22 thereof has a magnetic pole opposite to the magnetic pole of the undersurface 10 of the magnet section 1. It is desired that a thickness of a resin part 21 in a direction Y orthogonal to the direction X of the moving member 3 moves is a function of e<x> with respect to a moving distance of the moving member 3. With such an arrangement, an output of the element 30 within the member 3 varies linearly against the movement of the member 3. This enables the reading of the output of the element 30 directly as moving distance without any correction.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a position detection device.

[Conventional technology]

Conventionally, various types of position detection devices have been considered.One example is one that uses the inductance of a coil to determine the rotational position of a rotating body, etc.
It is shown in Japanese Patent No. 27266.

In the method disclosed in this publication, a long triangular metal band is wound around a rotating body, and a coil is provided opposite the metal band. Changes in the inductance of the coil based on changes in the area of the metal strip were detected to determine the rotational position of the rotating body.

[Invention or problem to be solved]

However, in a device that employs the detection method disclosed in the above publication, an oscillation circuit or the like must be connected to the coil, resulting in a complicated configuration.

Furthermore, since position detection is based on changes in inductance, the accuracy is insufficient and the detection range is narrow.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a small-sized position detection device that can perform highly accurate position detection over a long distance with a simple configuration.

[Means to solve the problem]

The position detection device of the present invention is a position detection device for detecting the position of a moving body moving on a rail, wherein the rail is configured with a magnetic force generating means whose magnetic flux density increases or decreases along the moving direction, and the moving body is The present invention is characterized in that it includes magnetic detection means for detecting changes in the magnetic flux density.

Further, it is preferable that the magnetic force generating body sandwich the magnetic detecting means in a direction perpendicular to the moving direction of the magnetic detecting means.

Furthermore, it is preferable that the magnetic flux density passing through the magnetic detection means increases or decreases linearly with respect to the direction of movement thereof.

[Effect]

Since the position detection device of the present invention is configured as described above, the magnetic flux density on the rail changes in an increasing or decreasing direction and interlinks the moving body. Magnetic field lines differ depending on location. Further, the output value of a magnetic detection element fixed to a moving body changes depending on the amount of interlinked lines of magnetic force. Therefore, the position of the moving body moving on the rail is detected as the output value of the magnetic detection element.

〔Example〕

Embodiments according to the present invention will be described below with reference to the drawings.

Elements with the same reference numerals have the same functions, so duplicate explanations will be omitted.

FIG. 1 shows a perspective view of an embodiment of the position detection device according to the present invention, FIG. 2(a) shows the front side of the position detection device, FIG. (c) shows the AA cross section of FIG. 2(a).

First, as shown in FIG. 1, the position detection device includes a rail composed of an upper magnet part 1 and a lower magnet part 2, and a Hall element 30 for magnetic detection sandwiched between them. It is composed of a moving member 3.

The upper magnet part 1 is an integrated permanent magnet, and its lower surface 10 is coated with resin.

Various resins can be used as this resin, but polyacetal resin is preferred in terms of corrosion resistance and abrasion resistance.

The lower magnet part 2 is composed of a resin part 21 and a permanent magnet part 22. The lower magnet section 2 is configured such that the upper surface 22a of the permanent magnet section 22 has a magnetic pole opposite to the magnetic pole of the lower surface 10 of the upper magnet section 1.

The thickness t of the resin portion 21 in the direction Y perpendicular to the moving direction X of the moving member 3 is preferably set as a function of ex with respect to the moving distance of the moving member 3. With this configuration, the Hall element 30 in the moving member 3
The output changes linearly with the movement of the moving member 3, and the output of the Hall element 30 can be directly read as the moving distance without any correction. This is because the properties of the Hall element change linearly with the magnetic flux density passing through it.
Further, the magnetic flux density decreases in inverse proportion to the square of the distance.

The upper magnet part 1 and the lower magnet part 2 are housed and fixed in a holder 4 made of a magnetic material, as shown in FIG. In FIG. 1, this holder 4 is shown by a chain double-dashed line. When each member is arranged in this way, magnetic lines of force W as shown in FIG. 2(C) are formed between the upper and lower magnet parts 1.2 and the holder 4.

These magnetic lines of force W pass through the holder 4, which is a magnetic material, and the upper magnet part 1 and the lower magnet part 2, and a magnetic circuit is formed. Therefore, the magnetic flux density passing through the Hall element 30 in the moving member 3 is stabilized. This enables stable position detection.

The moving member 3 includes a retainer 3 integrally molded from resin. Various resins can be used as this resin, and polyacetal resin is preferred in terms of corrosion resistance and abrasion resistance. As shown in FIG. 3, this retainer 31 includes a main body portion 32 shaped like a rectangular parallelepiped, a first pressing portion 34, and a second suppressing portion 35.
The main body portion 32 is provided with a cavity 33 for accommodating the Hall element 30. The first pressing portion 34 has a pantograph shape, as shown in FIG.
The top part contacts the lower surface 10 of the upper magnet part 1,
The Hall element 30 housed in the cavity 33 is pressed against the upper surface of the resin part 21 of the lower magnet part 2, and the movable member 3 is prevented from wobbling in the Z direction. On the other hand, the second suppressing part 35 also has a pantograph shape, as shown in FIG.
The main body part 32 is urged in a direction Y perpendicular to the pressing direction Z of the pressing part 34 and the moving direction X of the moving member 3, and the main body part 3
A part of the side surface 33 of the holder 2 is pressed against the inner surface 41 of the holder 4 to prevent the movable member 3 from wobbling in the Y direction.

With this configuration, the movable member 3 can smoothly move between the upper and lower magnet parts 1.2, and stable position detection is possible.

The present invention is not limited to the above embodiments, and various modifications may be made.

Specifically, in the above embodiment, the upper and lower magnet parts are configured using permanent magnets, but the structure is not limited to this, and electromagnets or the like may be used to change the magnetic flux density in the direction of movement. It can also be configured as Further, although the thickness t of the resin portion of the lower magnet portion is made to be a function of e, the thickness t is not limited to this, and may be made to change linearly, for example. In this case, in order to maintain linearity between the moving distance and the output value of the position detection device, it is necessary to correct the output value of the Hall element. Furthermore, in the above embodiment, the upper magnet part is an integral permanent magnet, and the lower magnet part is made up of two members, but the reverse may be used, or both may be made of two members. good.

Further, in the above embodiment, a pole element is used as the magnetic detection element, but the present invention is not limited to this, and other magnetic detection elements such as an MR element may be used.

Furthermore, in the above embodiment, a pantograph-shaped pressing portion that presses the moving member in two directions and in the Y direction is provided;
Position pressure detection can be performed with high precision even if a suppressing portion that presses only in the Z direction is provided. Such an example is shown in FIG. Alternatively, the Hall element may be built into a substantially rectangular resin member without providing such a pressing portion, and the Hall element may be slid on the side surface of the resin member or the upper and lower surfaces of the first and second magnet parts. . Further, in the above embodiment, the suppressing portion is formed into a pantograph shape by integral molding of resin, but it may be combined with a separate member, or
Such a pressing portion may be constructed of a leaf spring or the like.

Furthermore, in the above embodiments, the first and second magnet parts are fixed and the movable member is moved, or conversely, the movable member is fixed and the first and second magnet parts are moved. You may also do so.

〔Effect of the invention〕

As described above, in the position detection device of the present invention, a moving body equipped with a magnetic detection element is moved on a rail whose magnetic flux density changes in the moving direction, and the magnetic flux density detected by the magnetic detection element increases or decreases. Since the position of the moving body is determined by the following, highly accurate and stable position detection is possible.

Furthermore, by sandwiching the magnetic detecting element between magnetic force generators in a direction perpendicular to the direction of movement thereof, it is possible to stabilize the magnetic flux and enable stable position detection.

[Brief explanation of drawings]

FIG. 1 is a perspective external view of an embodiment of a position detection device according to the present invention, and FIG. 2 is a front view of the position detection device shown in FIG.
FIG. 3 is a diagram showing a side cross section, FIG. 3 is a diagram showing a holder for a magnetic detection element used in the position detection device shown in FIG. 1, and FIG. 4 is a diagram showing another example of a holder for a magnetic detection element. ] ・First magnet part, 2... second magnet part,
3. Moving parts. Representative Patent Attorney Yoshiki Hase
Fumiaki Terashima Figure 2 (b) Example of the samurai container (c) Figure 3

Claims (1)

[Claims] 1. A position detection device for detecting the position of a moving body moving on a rail, wherein the rail is configured with a magnetic force generating means whose magnetic flux density increases or decreases along the moving direction, A position detection device whose body includes magnetic detection means for detecting changes in the magnetic flux density. 2. The position detection device according to claim 1, wherein the magnetic force generating means inserts the moving body in a direction perpendicular to the moving direction. 3. The position detection device according to claim 1 or 2, wherein the magnetic flux density passing through the magnetic detection means of the magnetic force generation means changes as a linear function with respect to the direction of movement thereof.