JP2005300340A - Magnetic encoder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic encoder applicable over a range from low-speed rotation up to high-speed rotation. <P>SOLUTION: This magnetic encoder 1 relatively rotated with respect to detecting means 2, 3 for detecting the strength of a magnetic field has the first row of magnetic poles 4 for generating the magnetic field varied repeatedly at a first interval L1 along its circumferential direction, and a second row of magnetic poles 5 for generating the magnetic field, varied repeatedly at a second interval L2 wider than the first interval L1 along its circumferential direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a magnetic encoder used in a detection device that detects the rotation of a rotating member provided in, for example, an automobile, a home appliance, or the like.

  2. Description of the Related Art Conventionally, as this type of magnetic encoder, one used for a detection device that detects a rotational speed, such as a vehicle speed sensor that detects the vehicle speed of an automobile, is known. Patent Document 1 discloses a sealing device in which the surface of a metal having multiple magnetic poles in the circumferential direction is coated with an elastic body. Detected.

The rotation detection sensor can calculate the vehicle speed from the number of magnetic poles of the magnetic encoder and the circumference of the rotating body including the magnetic encoder. The rotation speed detection range is determined by the peripheral speed of the shaft rotation and the number of magnetized magnetic poles. When the high-speed rotation area is used regularly, the number of magnetic poles is reduced. There is a need.
Japanese Utility Model Publication No. 5-69464

  However, in the prior art, when it is necessary to detect the rotational speed in a wide range from low speed rotation to high speed rotation, it is necessary to provide a magnetic encoder and a magnetic sensor for low speed and high speed respectively. For this reason, it has been impossible to avoid an increase in installation space, an increase in the number of components, and an increase in the number of installation steps.

  The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide a magnetic encoder applicable from low speed rotation to high speed rotation.

  Another object of the present invention is to provide a magnetic encoder capable of obtaining a plurality of magnetic force waveforms.

  Another object of the present invention is to provide a magnetic encoder capable of obtaining two types of magnetic force waveforms with suppressed waveform loss due to interference.

In order to achieve the above object, the present invention provides:
A magnetic encoder that rotates relative to a detection means for detecting the strength of a magnetic field,
A first magnetic pole array that generates a magnetic field that repeatedly fluctuates at a first interval (wavelength) in the circumferential direction;
And a second magnetic pole array for generating a magnetic field that repeatedly fluctuates at a second interval wider (longer) than the first interval (wavelength) in the circumferential direction.

  In this way, a plurality of magnetic force waveforms having different intervals of repeated fluctuations can be obtained, so that a wide range from a low speed to a high speed rotation range can be detected using a single magnetic encoder.

  The first magnetic pole row and the second magnetic pole row are preferably arranged concentrically.

Further, it is preferable that the first magnetic pole array and the second magnetic pole array have S poles or N poles alternately arranged.

  In this way, it is possible to easily and stably generate a magnetic field that repeatedly varies at predetermined intervals in the circumferential direction.

The magnetic encoder is an annular member,
The first magnetic pole row is located on an inner peripheral portion of the annular member, and the second magnetic pole row is located on an outer peripheral portion of the annular member;
The direction of the magnetic pole is preferably substantially parallel to the rotation axis of the magnetic encoder.

  In this way, the two magnetic force waveforms can be detected with high accuracy with high accuracy by providing the detection means at respective positions facing one plane of the annular member in a direction substantially parallel to the rotation axis.

Alternatively, the magnetic encoder is an annular member,
The first magnetic pole row is located on an outer peripheral portion of the annular member, and the second magnetic pole row is located on an inner peripheral portion of the annular member;
The direction of the magnetic pole is preferably substantially parallel to the rotation axis of the magnetic encoder.

  In this way, the two magnetic force waveforms can be detected with high accuracy with high accuracy by providing the detection means at respective positions facing one plane of the annular member in a direction substantially parallel to the rotation axis. In addition, since the first magnetic pole row that generates a magnetic field that repeatedly fluctuates at a first interval narrower than the second interval in the circumferential direction is disposed on the outer peripheral portion, the first magnetic pole row having a large number of magnetic poles This increases the volume of the magnetic encoder and facilitates magnetization during the production of the magnetic encoder.

Alternatively, the magnetic encoder is an annular member,
The first magnetic pole row is located on one plane side of the annular member; the second magnetic pole row is located on the other plane side of the annular member;
The direction of the magnetic pole is preferably substantially perpendicular to the rotation axis of the magnetic encoder.

  In this way, by providing the detection means on the outer peripheral side or inner peripheral side of the annular member in a direction substantially perpendicular to the rotating shaft, two magnetic force waveforms can be detected with high accuracy.

  Further, it is preferable that the magnetic field generated by the first magnetic pole row is substantially zero in a phase corresponding to the surface of the magnetic encoder where the magnetic field generated by the second magnetic pole row is substantially zero. is there.

  Here, the phase corresponding to the surface of the magnetic encoder is the angle formed by the position where the magnetic encoder detects the magnetic field around the rotation axis and the predetermined point when the predetermined point on the surface of the magnetic encoder is used as a reference. (0 to 2π).

  In this way, the magnetic force waveform formed by each of the two magnetic pole rows can be obtained while suppressing the loss of the waveform due to interference, so that the detection means can accurately detect the rotational speed.

  Further, the first magnetic pole constituting the first magnetic pole row adjacent to the surface of the magnetic encoder corresponding to the phase at which the magnetic field generated by the first magnetic pole row and the second magnetic pole row becomes substantially zero It is preferable that the second magnetic pole constituting the second magnetic pole array facing the first magnetic pole is the same pole.

In this way, the magnetic force waveform formed by each of the two magnetic pole rows can be obtained while suppressing the loss of the waveform due to interference, so that the detection means can accurately detect the rotational speed.

  In addition, it is preferable that the number of magnetic poles of the first magnetic pole row is an odd multiple of the number of magnetic poles of the second magnetic pole row.

  In this way, the first magnetic pole row constituting the first magnetic pole row adjacent to the surface of the magnetic encoder corresponding to the phase at which the magnetic field generated by the first magnetic pole row and the second magnetic pole row becomes substantially zero. And the second magnetic pole constituting the second magnetic pole array opposite to the first magnetic pole can be made the same pole over the entire circumference of the magnetic encoder, and formed by two magnetic pole arrays, respectively. A magnetic force waveform can be obtained while suppressing waveform loss due to interference. Therefore, accurate detection of the rotational speed by the detection means is possible over the entire circumference.

  According to the present invention, it is possible to provide a magnetic encoder applicable from low speed rotation to high speed rotation.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the embodiments and the drawings. However, the functions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. . Further, the materials, shapes, etc. of the members once described in the following description are the same as those in the first description unless otherwise described.

  FIG. 1A is a top view of the magnetic encoder according to the first embodiment, and FIG. 1B is a cross-sectional view taken along the line AA in FIG.

  A magnetic encoder 1 according to the first embodiment is an annular member that rotates relative to detection means 2 and 3 that detect the strength of a magnetic field. The size of the annular member may be appropriately selected depending on the rotating member to be attached. In the first embodiment, a magnetic encoder having an outer diameter of 85 mm and an inner diameter of 68 mm will be described.

  Magnetic sensors are used as the detection means 2 and 3. A magnetic sensor is a sensor that detects magnetic energy. Specifically, a magnetic head using an electromagnetic induction action, a differential transformer, a Hall element using an action that converts magnetic force into electricity, an MR element ( A magnetoresistive effect element) or the like is preferable.

  The magnetic encoder 1 includes a first magnetic pole array 4 that generates a magnetic field that repeatedly fluctuates at a first interval L1 in the circumferential direction, and a second interval that is wider (longer) than the first interval (wavelength) L1 in the circumferential direction. And a second magnetic pole row 5 that generates a magnetic field that repeatedly fluctuates at (wavelength) L2. Therefore, two types of waveforms (magnetic force waveforms) having different magnetic field fluctuation periods can be generated by one magnetic encoder 1, and the number of components and the mounting space can be reduced. In addition, a single magnetic encoder applicable from low speed rotation to high speed rotation can be provided.

  The first magnetic pole row 4 and the second magnetic pole row 5 are arranged concentrically around the rotating shaft 6 of the magnetic encoder. Further, both the first magnetic pole row 4 and the second magnetic pole row 5 are alternately arranged with magnetic poles that are S poles or N poles. Therefore, when a magnetic field is detected by the detection means 2 and 3 from the rotation axis direction of the magnetic encoder, a magnetic field that fluctuates repeatedly at equal intervals in the circumferential direction can be easily detected.

  In the first embodiment, the first magnetic pole row 4 has 80 poles and the second magnetic pole row 5 has 16 poles. The number of magnetic poles of the first magnetic pole row 14 is 5 which is the number of magnetic poles of the second magnetic pole row 5. Double (odd multiple).

  The magnetization method was performed with an electromagnet having 80-pole and 16-pole metal yokes corresponding to the shape of the outer diameter and inner diameter. However, the production of the magnetic encoder according to the present invention is not limited to this method, and any method can be used as long as it can produce magnetic pole arrays having different numbers of poles.

  FIG. 3 shows the phase of the magnetic encoder and the strength of the magnetic field at that position when the magnetic means on the outer diameter side and inner diameter side of the magnetic encoder 1 are detected by the detection means 2 and 3 from the rotation axis direction of the magnetic encoder 1. It is the graph which showed magnetic force, magnetic flux density. Here, the strength of the magnetic field is indicated by its absolute value without distinguishing between the S pole and the N pole. The detected waveform is shown up to the phase θ3 shown in FIG.

  The first magnetic pole row 4 may be inside or outside the second magnetic pole row 5, but more preferably, the first magnetic pole row 4 is located on the outer peripheral portion of the annular member, and the second magnetic pole row 4 5 is good to be located in the inner peripheral part of an annular member. This is because the number of magnetic poles of the first magnetic pole row 4 is large, so that the volume per one magnetic pole is increased by arranging the first magnetic pole row 4 on the outer diameter side with a long circumference, and magnetization at the time of manufacturing the magnetic encoder becomes easy. . Here, the direction of the magnetic pole is the direction of the lines of magnetic force on the surface of the magnetic pole. Moreover, in Example 1, the direction of the magnetic pole is substantially parallel to the rotating shaft 6 of the magnetic encoder.

  Furthermore, in the first embodiment, the phases corresponding to the outer peripheral position 7 and the inner peripheral position 8 on the surface of the magnetic encoder where the magnetic field generated in the second magnetic pole row 5 is substantially zero (for example, the phase θ1 shown in FIG. In θ2, θ3), the magnetic field generated by the first magnetic pole row 4 is arranged to be substantially zero. By arranging in this way, the magnetic force waveforms respectively formed by the two magnetic pole rows can be obtained while suppressing the loss of the waveform due to interference, so that the detection means 2 and 3 can accurately detect the rotational speed.

  In addition to the above-described configuration, the magnetic field corresponding to the phase where the magnetic fields generated by the first magnetic pole row 4 and the second magnetic pole row 5 are substantially zero (for example, the phases θ1, θ2, and θ3 shown in FIG. 1). A magnetic pole 4a (magnetic pole 4b), which is a first magnetic pole constituting the first magnetic pole row 4, and a second magnetic pole row 5 opposed to the magnetic pole 4a (magnetic pole 4b) are adjacent to the encoder surfaces 7 and 8. The magnetic pole 5a (magnetic pole 5b) which is the second magnetic pole to be made is preferably the same pole.

  Specifically, in the first embodiment, the magnetic pole 4a and the magnetic pole 5a are S poles, and the magnetic pole 4b and the magnetic pole 5b are N poles. Therefore, the detection means 2 and 3 can accurately detect the rotational speed.

  In Example 2, the first magnetic pole row has 112 poles and the second magnetic pole row has 16 poles, and the number of magnetic poles of the first magnetic pole row is 7 times (odd multiple) the number of magnetic poles of the second magnetic pole row. There is a big difference in certain points. A description of the same configuration as that of the first embodiment is omitted.

  FIG. 4 shows the phase of the magnetic encoder and the strength of the magnetic field at the position when the magnetic means on the outer diameter side and the inner diameter side of the magnetic encoder 1 are detected by the detection means 2 and 3 from the rotation axis direction of the magnetic encoder 1. It is the shown graph. Here, the strength of the magnetic field is indicated by its absolute value without distinguishing between the S pole and the N pole. The detected waveform is shown up to the phase θ3 shown in FIG.

As shown in FIG. 4, also in the second embodiment, the magnetic force waveforms respectively formed by the two magnetic pole rows can be obtained without loss of the waveform due to interference, and the detection means 2 and 3 can accurately detect the rotational speed. Become.

  As in the configurations of the first and second embodiments, in the present invention, the number of magnetic poles of the first magnetic pole row 4 may be an odd multiple of the number of magnetic poles of the second magnetic pole row 5. . With such a configuration, the first magnetic pole row adjacent to the surface of the magnetic encoder corresponding to the phase at which the magnetic field generated by the first magnetic pole row 4 and the second magnetic pole row 5 is substantially zero is obtained. It is possible to make the first magnetic pole constituting and the second magnetic pole constituting the second magnetic pole row 5 facing the first magnetic pole the same pole over the entire circumference of the magnetic encoder.

(Comparative Example 1)
In the magnetic encoder 11 used in Comparative Example 1, the first magnetic pole row 14 has 80 poles and the second magnetic pole row 15 has 16 poles as in the first embodiment (see FIG. 7). However, the surfaces 17 and 18 of the magnetic encoder corresponding to phases (for example, θ1, θ2, and θ3 shown in FIG. 7) in which the magnetic fields generated by the first magnetic pole row 14 and the second magnetic pole row 15 are substantially zero. Adjacent to the magnetic pole 14a (magnetic pole 14b), which is the first magnetic pole constituting the first magnetic pole row 14, and the second magnetic pole constituting the second magnetic pole row 15 facing the magnetic pole 14a (magnetic pole 14b). This is a pole different from the magnetic pole 15a (magnetic pole 15b).

  When the magnetic encoder 11 was rotated and detected by the detection means 12 and 13, 16 poles were detected on the inner diameter side where the second magnetic pole row 15 was arranged, as in the first embodiment. However, unlike the first embodiment, only 48 poles were detected on the outer diameter side where the first magnetic pole row 14 was disposed. This is because the first magnetic pole and the second magnetic pole are different from each other, the first magnetic pole and the second magnetic pole both weaken their strengths, and the magnetic field generated by the magnetic poles 14a and 14b having a particularly small volume. This is considered to be because the strength of the steel was lowered (see FIG. 5). Therefore, in the configuration shown in Comparative Example 1, a magnetic pole that cannot be detected by the detection unit 12 is generated, and the rotational speed cannot be accurately detected.

(Comparative Example 2)
The magnetic encoder used in Comparative Example 2 has 112 poles for the first magnetic pole row and 16 poles for the second magnetic pole row, as in the second embodiment. However, the first magnetic pole constituting the first magnetic pole row adjacent to the surface of the magnetic encoder corresponding to the phase where the magnetic field generated by the first magnetic pole row and the second magnetic pole row is substantially zero, and The second magnetic pole is different from the second magnetic pole constituting the second magnetic pole row and facing the first magnetic pole.

  When the magnetic encoder described above was rotated and detected by the detection means, 16 poles were detected on the inner diameter side where the second magnetic pole row was arranged, as in Example 2. However, unlike the second example, only 80 poles were detected on the outer diameter side where the first magnetic pole row 14 was disposed. This is because the first magnetic pole and the second magnetic pole are different poles, so the first magnetic pole and the second magnetic pole both weaken their strength. This is thought to be due to the decrease (see FIG. 6). Therefore, in the configuration shown in Comparative Example 2, a magnetic pole that cannot be detected by the detection unit is generated, and the rotational speed cannot be accurately detected.

  FIG. 2A is a side view of the magnetic encoder according to the third embodiment. 2B is a top view of the magnetic encoder of FIG. 2A viewed from the B direction, and FIG. 2C is a top view of the magnetic encoder of FIG. 2A viewed from the C direction.

The magnetic encoder 21 used in the third embodiment is characterized in that the first magnetic pole row 24 is located on the one plane 29 side of the annular member, and the second magnetic pole row 25 is located on the other plane 30 side of the annular member. It is. In the third embodiment, the direction of the magnetic pole is substantially perpendicular to the rotating shaft 26 of the magnetic encoder. Here, the direction of the magnetic pole is the direction of the lines of magnetic force on the surface of the magnetic pole, and is the direction shown in FIGS.

  The magnetic encoder 21 is an annular member that rotates relative to the detection means 22 and 23 that detect the strength of the magnetic field.

  The magnetic encoder 21 includes a first magnetic pole row 24 that generates a magnetic field that repeatedly fluctuates at a first interval L3 in the circumferential direction, and a magnetic field that fluctuates repeatedly at a second interval L4 that is wider than the first interval L3 in the circumferential direction. And a second magnetic pole row 25 for generating Therefore, two types of waveforms (magnetic force waveforms) having different magnetic field fluctuation periods can be generated by one magnetic encoder 21, and the number of parts and the mounting space can be reduced. In addition, a single magnetic encoder applicable from low speed rotation to high speed rotation can be provided.

  The first magnetic pole row 24 and the second magnetic pole row 25 are arranged concentrically around the rotating shaft 26 of the magnetic encoder. Further, both the first magnetic pole array 24 and the second magnetic pole array 25 are alternately arranged with magnetic poles that are S poles or N poles. Therefore, when a magnetic field is detected by the detection means 22 and 23 from the outer peripheral side of the magnetic encoder, it is possible to easily detect a magnetic field that fluctuates repeatedly at equal intervals in the circumferential direction.

  In Example 3, the first magnetic pole row 24 has 80 poles and the second magnetic pole row 25 has 16 poles. The number of magnetic poles of the first magnetic pole row 24 is 5 that is the number of magnetic poles of the second magnetic pole row 25. Double (odd multiple).

  In the third embodiment, the phases corresponding to the positions 27 and 28 on the surface of the magnetic encoder where the magnetic field generated in the second magnetic pole row 25 is substantially zero (for example, the phases θ11, θ12, and θ13 shown in FIG. 2). ), The magnetic field generated by the first magnetic pole row 24 is arranged to be substantially zero. By arranging in this way, the magnetic force waveforms respectively formed by the two magnetic pole rows can be obtained while suppressing the loss of the waveform due to interference, so that the detection means 22 and 23 can accurately detect the rotational speed.

  In addition to the above-described configuration, the magnetic encoder corresponding to the phase (for example, θ11, θ12, θ13 shown in FIG. 2) in which the magnetic fields generated by the first magnetic pole row 24 and the second magnetic pole row 25 are substantially zero. A magnetic pole 24a (magnetic pole 24b) constituting the first magnetic pole row 24 adjacent to the surfaces 27 and 28, and a magnetic pole 25a (magnetic pole 25b) constituting the second magnetic pole row 25 facing the magnetic pole 24a (magnetic pole 24b). Should be the same pole.

  Specifically, in the third embodiment, the magnetic pole 24a and the magnetic pole 25a are S poles, and the magnetic pole 24b and the magnetic pole 25b are N poles. Therefore, the detection means 22 and 23 can accurately detect the rotational speed.

1A is a top view of a magnetic encoder according to Embodiment 1. FIG. (B) It is AA sectional drawing of (a). (A) It is a side view of the magnetic encoder which concerns on Example 3. FIG. (B) It is the top view which looked at the magnetic encoder of (a) from the B direction. (C) It is the top view which looked at the magnetic encoder of (a) from the C direction. 3 is a graph showing a part of a detected waveform according to Example 1. 6 is a graph showing a part of a detected waveform according to Example 2. 10 is a graph showing a part of a detected waveform according to Comparative Example 1. 10 is a graph showing a part of a detected waveform according to Comparative Example 2. 6 is a top view of a magnetic encoder according to Comparative Example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Magnetic encoder 2, 3 Detection means 4 1st magnetic pole row 4a, 4b Magnetic pole (1st magnetic pole)
5 Second magnetic pole array 5a, 5b Magnetic pole (second magnetic pole)
6 Rotating shaft 7 Surface

Claims (9)

A magnetic encoder that rotates relative to a detection means for detecting the strength of a magnetic field,
A first magnetic pole array that generates a magnetic field that repeatedly fluctuates at a first interval in the circumferential direction;
And a second magnetic pole row for generating a magnetic field that repeatedly fluctuates at a second interval wider than the first interval in the circumferential direction.   The magnetic encoder according to claim 1, wherein the first magnetic pole row and the second magnetic pole row are arranged concentrically.   3. The magnetic encoder according to claim 1, wherein the first magnetic pole row and the second magnetic pole row have magnetic poles that are S poles or N poles arranged alternately. The magnetic encoder is an annular member;
The first magnetic pole row is located on an inner peripheral portion of the annular member, and the second magnetic pole row is located on an outer peripheral portion of the annular member;
4. The magnetic encoder according to claim 1, wherein the direction of the magnetic pole is substantially parallel to a rotation axis of the magnetic encoder. The magnetic encoder is an annular member;
The first magnetic pole row is located on an outer peripheral portion of the annular member, and the second magnetic pole row is located on an inner peripheral portion of the annular member;
4. The magnetic encoder according to claim 1, wherein the direction of the magnetic pole is substantially parallel to a rotation axis of the magnetic encoder. The magnetic encoder is an annular member;
The first magnetic pole row is located on one plane side of the annular member; the second magnetic pole row is located on the other plane side of the annular member;
4. The magnetic encoder according to claim 1, wherein the direction of the magnetic pole is substantially perpendicular to a rotation axis of the magnetic encoder.   The magnetic field generated by the first magnetic pole row is substantially zero in a phase corresponding to the surface of the magnetic encoder where the magnetic field generated by the second magnetic pole row is substantially zero. Item 7. The magnetic encoder according to any one of Items 4 to 6.   A first magnetic pole constituting the first magnetic pole row adjacent to the surface of the magnetic encoder corresponding to the phase at which the magnetic field generated by the first magnetic pole row and the second magnetic pole row is substantially zero; The magnetic encoder according to claim 7, wherein the second magnetic pole constituting the second magnetic pole array facing the first magnetic pole is the same pole.   The magnetic encoder according to claim 1, wherein the number of magnetic poles of the first magnetic pole row is an odd multiple of the number of magnetic poles of the second magnetic pole row.

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