JP2003257738A - Permanent magnet, its manufacturing method, and position sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a permanent magnet that can be improved in detection sensitivity when the magnet is used as a position sensor. <P>SOLUTION: This permanent magnet 11 is magnetized so that its magnetic flux density may gradually increase from one end section to the other end section at a fixed gradient. In a method of manufacturing the permanent magnet 11, a magnetic material 11' is magnetized in a parallel magnetic field after the material 11' is disposed in the parallel magnetic field so that, for example, a magnetic flux passing through the magnetic material 11' in the magnetic field may gradually increase from one end section to the other end section of the material 11'. <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 permanent magnet, a method for manufacturing a permanent magnet, and a position sensor.

[0002]

2. Description of the Related Art FIG. 9 conceptually shows a conventional position sensor using a permanent magnet, and particularly shows a position sensor for detecting a rotation angle of a rotary shaft. That is, in this position sensor, the ring-shaped permanent magnet 1 magnetized so that the N poles and the S poles are alternately arranged is provided on the rotating shaft 2 that is the detected body, while the magnetic flux detecting means is provided in the portion that becomes the fixed body. 3 is provided. When the permanent magnet 1 is configured, the configuration shown in FIG.
As shown in FIG. 5, a magnetizing yoke 4 in which N poles and S poles are alternately arranged is applied, and a magnetic body 1 ′ is inserted into the magnetizing yoke 4 and magnetized.

According to the position sensor constructed as described above, the detection result of the magnetic flux detecting means 3 becomes a pulse-like waveform as shown in FIG. 11 as the rotary shaft 2 rotates. Therefore, if the number of pulses is counted by the controller 5,
The rotation angle of the rotary shaft 2 can be detected.

[0004]

In the position sensor to which the above-mentioned permanent magnet 1 is applied, the detection sensitivity is defined by the mutual distance between the N pole and the S pole. That is, if the mutual distance between the N pole and the S pole is set to be narrow, the magnetic flux detecting means 3 can detect the change in the magnetic flux even when the rotation angle of the rotary shaft 2 is small, and the detection sensitivity thereof is It becomes possible to raise.

However, in the permanent magnet 1 in which the N poles and the S poles are alternately arranged, there is a limit in narrowing the mutual distance between them, and accordingly, the detection sensitivity of the position sensor is naturally limited. Become so.

Further, the magnetizing yoke 4 applied when magnetizing the magnetic body 1'is dedicated for each size and shape of the permanent magnet 1 and for each mutual gap between the N pole and the S pole. Need to prepare. As a result, this is a factor that significantly increases the manufacturing cost of the permanent magnet 1.

Further, as shown in FIG. 12, in the position sensor having a magnetic circuit in which the uniformly magnetized permanent magnets 6 are arranged so that the poles are reversed, the magnetic flux detecting means is provided in the slit portion of the fixed portion magnetic material 7. There is a method of arranging 8. The magnetic flux detected in this magnetic circuit has the characteristics shown in FIG. A position sensor having a magnetic circuit having the characteristics shown in FIG. 13 has a problem in that when the permanent magnet 6 falls off, the intermediate position is output, and it is not determined that the sensor has failed.

In view of the above situation, it is an object of the present invention to provide a permanent magnet capable of enhancing its detection sensitivity when applied as a position sensor.

In addition, a method capable of reducing the cost when magnetizing the permanent magnet and enhancing the detection sensitivity,
Furthermore, it aims at providing the position sensor which can respond to the fail-safe of a sensor.

[0010]

In order to achieve the above object, a permanent magnet according to claim 1 is attached so that the magnetic flux density is not uniform from one end to the other end. Characterized by being magnetized. That is, it is characterized in that the magnetic flux density is magnetized so as to gradually increase or decrease from one end to the other end.

According to the present invention, the magnetic flux density varies depending on the detection position. Therefore, even if the amount of change in position is small, the position can be accurately detected based on the detected magnetic flux, and the detection sensitivity can be increased.

A second aspect of the present invention is the permanent magnet according to the first aspect, wherein the magnetic flux density changes with a constant gradient.

According to the present invention, the amount of change in the magnetic flux is always constant from one end to the other end.

In the method for manufacturing a permanent magnet according to a third aspect, the magnetic flux transmitted in the parallel magnetic field is magnetized so as to gradually change from one end to the other end with the same tendency. Characterize.

According to the present invention, the magnetizing of a permanent magnet whose magnetic flux density gradually changes from one end to the other end in a parallel magnetic field without using a dedicated magnetizing yoke. Is possible.

According to a fourth aspect of the present invention, there is provided a permanent magnet manufacturing method, wherein the magnetic body according to the third aspect has flexibility.
In addition, a flat plate is applied, and the magnetic body is arranged in the parallel magnetic field in a deformed state.

According to the present invention, by appropriately changing the shape of the flexible magnetic body, the magnetic flux transmitted in the parallel magnetic field gradually has a similar tendency from one end to the other end. It is possible to arrange the magnetic body so as to change.

Further, a manufacturing method of a permanent magnet according to a fifth aspect is characterized in that, in the fourth aspect, the magnetic body is deformed so as to be curved from one end portion to the other end portion.

According to the present invention, by deforming the magnetic body so as to curve from one end to the other end, the magnetic flux transmitted in the parallel magnetic field is transferred from one end to the other end. It is possible to arrange the magnetic body so as to gradually change with the same tendency. Moreover, the shape of the permanent magnet can be arbitrarily changed after the magnetization.

A method for manufacturing a permanent magnet according to claim 6 is characterized in that, in claim 4, the magnetic body is twisted and deformed in such a manner that one end and the other end rotate relative to each other. To do.

According to the present invention, by twisting and deforming the magnetic body in such a manner that one end and the other end are inclined with respect to each other, the magnetic flux transmitted in the parallel magnetic field changes from one end to the other. It is possible to arrange the magnetic body so as to gradually change toward the end portion with the same tendency. Moreover, the shape of the permanent magnet can be arbitrarily changed after the magnetization.

Further, according to a seventh aspect of the present invention, in the method of manufacturing a permanent magnet according to the third aspect, the magnetizer and the magnetic body are relatively gradually moved in one direction, and the magnetizer and the magnetic body are relatively moved. By gradually changing the magnetizing current of the magnetizer according to the amount of movement, the magnetic flux density of the magnetic body is magnetized so as to gradually change from one end to the other end with the same tendency. It is characterized by

According to the present invention, the magnetizing of the permanent magnet whose magnetic flux density gradually changes from one end to the other end in the parallel magnetic field without using a dedicated magnetizing yoke. Is possible.

According to the eighth aspect of the present invention, in the position sensor, the permanent magnet magnetized so that the magnetic flux density gradually changes from one end to the other end with the same tendency, and the displacement of the object to be detected. According to, the relative magnet is relatively moved from one end to the other end of the permanent magnet, and the magnetic flux detection means for detecting the magnetic flux of the facing portion in the permanent magnet,
It is characterized in that the detection result of the magnetic flux detecting means is output as position information of the detected object.

According to the present invention, the magnetic flux detected by the magnetic flux detecting means varies depending on the detection position. Therefore, even if the amount of change in position is small, the position can be accurately detected based on the detected magnetic flux, and the detection sensitivity can be increased.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of a permanent magnet, a method for manufacturing a permanent magnet and a position sensor according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a position sensor according to an embodiment of the present invention. The position sensor illustrated here is for detecting the rotation angle of the rotary shaft 10 that is the object to be detected. The permanent magnet 11 is provided on the peripheral surface of the rotary shaft 10 while the magnetic flux is detected at the portion that becomes the fixed body. The means 12 is provided and configured.

The permanent magnet 11 is a so-called flexible magnet, and has a flexible flat plate shape. The permanent magnet 11 is magnetized so that the magnetic flux density gradually increases from one end to the other end. Specifically, as shown in FIG. 2, after the magnetic body 11 ′ is attached to the curved surface 21 of the jig 20 so as to follow the magnetic body 11 ′, the magnetic body 11 ′ is arranged in a parallel magnetic field of a general-purpose magnetizer such as an air-core coil. I am trying to magnetize by doing. In the curved surface 21 of the jig 20, the magnetic flux (arrow in FIG. 2) passing through the magnetic body 11 ′ attached in the parallel magnetic field gradually increases from one end to the other end with a constant gradient. It is formed as follows. In the present embodiment, one end of the magnetic body 11 'is parallel to the magnetic flux of the parallel magnetic field,
The curved surface 21 of the jig 20 is configured such that the other end of the magnetic body 11 'is orthogonal to the magnetic flux of the parallel magnetic field. The magnetized permanent magnet 11 is attached to the peripheral surface of the rotary shaft 10 after being curved and deformed following the peripheral surface of the rotary shaft 10.

The magnetic flux detecting means 12 is for detecting the magnetic flux of the permanent magnet 11 and giving the detection result to the control section 13, and is provided at a portion facing the surface of the permanent magnet 11.

According to the position sensor constructed as described above, as described above, the permanent magnet 11 is magnetized so that the magnetic flux density gradually increases from one end to the other end. Therefore, the magnetic flux density becomes different according to the detection position of the magnetic flux detecting means 12, that is, according to the rotation angle of the rotating shaft 10. Therefore, the rotating shaft 10
Even if the rotation angle of the
The rotation angle can be accurately detected based on the magnetic flux detected by, and the detection sensitivity can be improved. Moreover, as shown in FIG.
Since the magnetic flux detected by 2 and the rotation angle of the rotary shaft 10 have a proportional relationship, the amount of change in the magnetic flux is always constant,
The detection sensitivity can be enhanced over a wide range regardless of the rotation angle of the rotating shaft 10. Further, as the control unit 13,
The function for counting the number of pulses is unnecessary as compared with the conventional one. Further, as described above, when magnetizing, it is not necessary to use a dedicated magnetizing yoke. As a result, it is possible to reduce the manufacturing cost.

In the embodiment described above, while the magnetized permanent magnet 11 is attached to the peripheral surface of the rotary shaft 10,
Although the magnetic flux detecting means 12 is provided in the portion which becomes the fixed body, the permanent magnet 11 and the magnetic flux detecting means 12 are provided.
The arrangement mode may be reversed. That is, while the magnetic flux detecting means is provided on the rotating shaft, the permanent magnet may be provided on the portion that becomes the fixed body.

Further, in the above-described embodiment, the position sensor which detects the rotation angle of the rotary shaft 10 by attaching the magnetized permanent magnet 11 to the peripheral surface of the rotary shaft 10 is provided. Although illustrated, the present invention is not necessarily limited to the rotary shaft 1.
It is not limited to the detection of the rotation angle of 0.

For example, as in the first modification shown in FIG.
If the permanent magnet 11 after being magnetized is formed into a flat plate shape and attached to the slide member 14, the position when the slide member 14 slides can be detected.

Also in this modified example 1, since the permanent magnet 11 is magnetized so that the magnetic flux density gradually increases from one end to the other end, the magnetic flux detecting means 12 is used. The magnetic flux density varies depending on the detection position, that is, the amount of sliding of the slide member 14. Therefore, even when the slide amount of the slide member 14 is small, the slide amount can be accurately detected based on the magnetic flux detected by the magnetic flux detecting means 12, and the detection sensitivity can be improved. Become. Moreover, since the magnetic flux detected by the magnetic flux detecting means 12 and the slide amount of the slide member 14 are in a proportional relationship, the amount of change in the magnetic flux is always constant, and the detection sensitivity is wide over a wide range regardless of the slide position of the slide member 14. Can be increased. Further, the controller 13 does not need a function for counting the number of pulses, and when magnetizing, it is not necessary to use a dedicated magnetizing yoke, so that the manufacturing cost can be reduced. It is the same.

In the above-described embodiment, the jig 20 is used.
After the magnetic body 11 'is attached to the curved surface 21 of the above so as to follow the magnetic body 11', the magnetic body 11 'is magnetized.
The present invention is not necessarily limited to this.

For example, as in the second modification shown in FIG.
The magnetic body 11 'and the magnetic core 31 of the magnetizer 30 are relatively moved in one direction, and the magnetizing current of the magnetizer 30 is gradually increased according to the relative movement amount of the magnetic body 11' and the magnetic core 31. You may make it increase.

As the magnetic body 11 ', as in the embodiment, a flexible flat plate may be applied. However, when magnetized, it is not necessary to deform the magnetic body 11 ′, and the magnetic body 11 ′ may remain flat. As the magnetizer 30, one provided with a magnetic core 31 having a substantially C-shape wound with a magnetizing coil 32 is applied. When the magnetic body 11 'and the magnetic core 31 are moved relative to each other, either one may be moved, or both may be moved.

Even when the magnetic body 11 'is magnetized as described above, it is possible to obtain the permanent magnet 11 in which the magnetic flux density gradually increases from one end to the other end. Therefore, even when this permanent magnet 11 is applied instead of the permanent magnet 11 of the embodiment, it is possible to achieve the same effect as that of the embodiment. In this case, since it is not necessary to use a dedicated magnetizing yoke, the manufacturing cost can be reduced as in the case of the embodiment.

Further, in the above-described embodiment, one end of the magnetic body 11 'is parallel to the magnetic flux of the parallel magnetic field, while the other end of the magnetic body 11' is parallel to the magnetic flux of the parallel magnetic field. Since the permanent magnets 11 are magnetized, they are magnetized on both sides. Further, in the modified example 2 as well, the permanent magnet 11 after being magnetized is magnetized on both sides. However, the magnetization pattern of the permanent magnet 11 is not limited to double-sided magnetization.

For example, as in the third modification shown in FIG.
Both ends of the magnetic body 11 'are magnetic fluxes of parallel magnetic fields (Fig. 6).
If the magnetic body 11 'is arranged so that the central part thereof is parallel to the magnetic flux of the parallel magnetic field, the permanent magnet 11 after magnetized becomes one-sided two-pole magnetized. .

Further, as in Modification 4 shown in FIG. 7, the magnetic body 11 'is twisted and deformed in such a manner that one end and the other end rotate 180 ° with respect to each other, and both ends are parallel to each other. If the permanent magnet 11 is magnetized so as to be orthogonal to the magnetic flux (arrow in FIG. 7) of the magnetic field, the magnetized permanent magnet 11 becomes one-sided two-pole magnetized.

Even when the manufacturing methods of the modified examples 3 and 4 are applied, as shown in FIG. 8, the permanent magnet 11 whose magnetic flux density gradually increases from one end to the other end is provided. You will be able to get it. Therefore, even when the permanent magnets 11 of the modified examples 3 and 4 are applied in place of the permanent magnet 11 of the embodiment, it is possible to obtain the same effect as that of the embodiment. In this case, since it is not necessary to use a dedicated magnetizing yoke, the manufacturing cost can be reduced as in the case of the embodiment.

Further, in the conventional magnetic position sensor, the measurement range is set around the output value zero or including the zero point. The reason is that the linearity is the highest in the vicinity of the zero point, but when the magnet according to the present embodiment in which the single magnetic field changes, the measurement range can be set without including the zero point. By doing so, if the output becomes zero, it can be determined that the sensor has failed (fail safe). In the conventional sensor, zero output is also a normal value, and therefore another failure determination means is required to determine a failure. Further, since the conventional sensor is configured so that the facing area of the magnet with respect to the magnetic member changes, a magnetic member is required, but the permanent magnet according to the present embodiment changes the magnetic flux density only by moving. Therefore, no magnetic member is required.

Therefore, in the sensor using the permanent magnet according to the present embodiment, when the permanent magnet comes off, the non-set range signal is output and it is determined that the sensor has failed. Therefore, it is possible to deal with the fail-safe of the sensor.

[0045]

As described above, according to the present invention, a permanent magnet capable of increasing its detection sensitivity when applied as a position sensor and a cost for magnetizing this permanent magnet are reduced. It is possible to obtain a position sensor capable of improving the method and the detection sensitivity, and capable of dealing with the fail-safe of the sensor.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a configuration of a position sensor according to an embodiment of the present invention.

FIG. 2 is a perspective view conceptually showing a method of manufacturing a permanent magnet.

FIG. 3 is an explanatory diagram showing a relationship between a change in the position of an object to be detected and a detection result of a magnetic flux detecting means in the position sensor shown in FIG.

FIG. 4 is a conceptual diagram showing a modified example 1 of the position sensor shown in FIG.

5 is a conceptual diagram showing a second modification of the method for manufacturing the permanent magnet shown in FIG.

FIG. 6 is a conceptual diagram showing a modified example 3 of the method for manufacturing the permanent magnet shown in FIG.

FIG. 7 is a conceptual diagram showing a modified example 4 of the method for manufacturing the permanent magnet shown in FIG.

8 is an explanatory diagram showing the relationship between the change in the position of the object to be detected and the detection result of the magnetic flux detecting means in the position sensor to which the permanent magnets manufactured by the methods of FIGS. 6 and 7 are applied.

FIG. 9 is a conceptual diagram showing a configuration of a conventional position sensor.

FIG. 10 is a conceptual diagram showing a conventional permanent magnet manufacturing method.

11 is a graph showing the relationship between the change in the position of the object to be detected and the detection result of the magnetic flux detecting means in the position sensor shown in FIG.

FIG. 12 is a conceptual diagram showing the configuration of another conventional position sensor.

13 is an explanatory diagram showing magnetic flux characteristics in the position sensor shown in FIG.

[Explanation of symbols]

10 rotation axis 11 permanent magnets 11 'magnetic material 12 Magnetic flux detection means 13 Control unit 14 Slide member 20 jigs 21 curved surface 30 magnetizer 31 magnetic core 32 magnetizing coil

Claims (8)

[Claims] 1. A permanent magnet characterized in that it is magnetized from one end toward the other end so that the magnetic flux density is not uniform. 2. The permanent magnet according to claim 1, wherein the magnetic flux density changes with a constant gradient. 3. A method for producing a permanent magnet, wherein the magnetic flux transmitted in a parallel magnetic field is magnetized so that it gradually changes from one end to the other end with the same tendency. 4. A magnetic material having flexibility and having a flat plate shape is applied as the magnetic material, and the magnetic material is arranged in the parallel magnetic field in a deformed state. A method for producing the permanent magnet described. 5. The method for manufacturing a permanent magnet according to claim 4, wherein the magnetic body is deformed so as to be curved from one end to the other end. 6. The method for manufacturing a permanent magnet according to claim 4, wherein the magnetic body is twisted and deformed in such a manner that one end and the other end rotate relative to each other. 7. The magnetizer and the magnetic body are relatively gradually moved in one direction, and the magnetizing current of the magnetizer is gradually changed according to the relative movement amount of the magnetizer and the magnetic body. 4. The method for manufacturing a permanent magnet according to claim 3, wherein the magnetic flux is magnetized so that the magnetic flux density of the magnetic body gradually changes from one end to the other end with the same tendency. 8. A permanent magnet magnetized so that the magnetic flux density gradually changes from one end to the other end with the same tendency, and one of the permanent magnets is arranged according to the displacement of the object to be detected. And a magnetic flux detecting unit that relatively moves from one end to the other end and detects the magnetic flux of the facing portion of the permanent magnet, and the detection result of the magnetic flux detecting unit is the position information of the detected object. The position sensor is characterized by outputting as.