JP2003215146A - Rotational speed sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance detection precision for rotational speed in a rotational speed sensor. <P>SOLUTION: A magnet aggregate 30 contains a plurality of magnet parts 30a, 30b,..., and is brought into the condition where N poles and S poles are positioned alternately in one-end parts thereof. Each detecting part 32 includes a yoke 37 containing a projected part 42 opposed to the N pole, a yoke 38 containing a projected part 44 opposed to the S pole, and a Hall element 35 therebetween. A magnetic circuit is formed to constitute a route through the magnet part 30a, the yoke 37, the Hall element 35, the yoke 38 and the magnet part 30a, and a direction of a magnetic field applied to the Hall element 35 is varied in accompaniment to rotation of the magnet aggregate 30 to change a direction of a voltage. Since the rotational speed is found based on the change of the voltage caused by a change of the opposed condition of the magnetic poles in the plurality of positions between the magnet aggregate 30 and the detecting parts 32, an influence of eccentricity on the rotational speed is reduced even when the magnet aggregate 30 and the detecting parts 32 are eccentrically provided to the rotation center line L. <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 rotation speed sensor, and more particularly to a rotation speed sensor, which includes a detection portion and a detection portion which are arranged close to each other and are rotatable relative to each other around a rotation center line. The section includes an electric signal generating section that generates an electric signal corresponding to a change in the physical state of itself due to relative rotation between itself and the detected section, and based on the change in the electric signal from the electric signal generating section. The present invention relates to a rotation speed sensor of a type that detects the speed of the relative rotation.

[0002]

2. Description of the Related Art An example of a rotational speed sensor of the above type is described in Japanese Patent Application Laid-Open No. 11-166840. In this rotation speed sensor, the detected portion includes a magnetic body having slits formed at predetermined intervals in the circumferential direction, and the detection portion includes a paramagnetic body and a Hall element. The object to be detected is attached to the rotating body, and the detecting unit is attached to the non-rotating body in a state where a magnetic circuit including a magnetic body, a Hall element, and a paramagnetic body is formed. When the rotating body is rotated around the rotation center line, the magnetic body is rotated and the magnetic field applied to the Hall element changes periodically. The electric signal generated in the hall element periodically changes, and the rotation speed of the rotating body is detected based on the periodic change of the electric signal.

[0003]

In the above rotation speed sensor, the rotation speed can be accurately detected when the detected portion is attached eccentrically to the rotation center line. There was a problem that I could not. Then, the subject of this invention is improving the detection precision of the relative speed of a to-be-detected part and a detection part in a rotation speed sensor. In particular, it is to reduce the influence of eccentricity on the rotation speed. This problem is solved by using a rotation speed sensor having the configuration of each of the following aspects. Similar to the claims, each mode is divided into paragraphs, each paragraph is given a number, and the numbers of other paragraphs are referred to as necessary. This is merely for facilitating the understanding of the technology described in the present specification, and it should not be construed that the technical features described in the present specification and a combination thereof are limited to the following items. Absent. Further, when a plurality of items are described in one section, it is not always necessary to adopt all the items together, and it is possible to take out only some of the items and adopt them.

Of the following items, (2) corresponds to claim 1, (9) corresponds to claim 2, (13) corresponds to claim 3, and (16). Corresponds to claim 4. Also, (18),
Items (19) and (22) correspond to claims 5, 6 and 7, respectively.

(1) A detection unit and a detection unit which are arranged close to each other and are rotatable relative to each other about a rotation center line, and the detection unit includes at least the detection unit and the detection unit. A rotation speed that includes an electric signal generation unit that generates an electric signal corresponding to a change in the physical state of the detection unit due to the relative rotation, and that detects the speed of the relative rotation based on the change in the electric signal from the electric signal generation unit. Sensor. In the rotation speed sensor described in this section, the electrical signal from the electrical signal generator changes with the relative rotation of the detected part and the detection part that are provided close to each other. The rotation speed is detected. The rotation speed sensor may have any structure as long as the electric signal from the electric signal generating portion is changed in accordance with the relative rotation between the detected portion and the detecting portion. The principle of the displacement sensor can be widely applied. For example, the electric signal generator may generate an electric signal according to a magnetic change of the detector accompanying relative rotation, generate an electric signal according to an optical change, or generate an electric signal. For example, an electric signal corresponding to the change can be generated. Specifically, a state in which a magnetic circuit including the detected portion and the detected portion is formed, and the direction and strength of the magnetic field in the magnetic circuit change due to relative rotation between the detected portion and the detected portion. Set up in. The electric signal generator generates an electric signal according to the change in the magnetic field of the magnetic circuit. The electric signal generator can be a Hall element, a magnetoresistive element, or a coil. In addition, the detected portion can be in a light-shielded state and a light-transmitted state (for example, has a slit or unevenness), and the detection portion is
A light receiving state detecting unit (for example, one including a light emitting unit and a light receiving unit) is included. The light receiving state of the detection part changes according to the relative rotation between the detected part and the detection part,
An electric signal corresponding thereto is generated by the light receiving state detector. Further, the area of a portion of the detection unit and a predetermined portion of the detected portion, which face each other in close proximity to each other, changes with the relative rotation of the detected portion and the detection unit,
It is possible to form an electric circuit including the portions facing each other in close proximity to each other so that the portions facing in close proximity to each other function as a capacitor. Along with the relative rotation of the detected part and the detected part, the facing area changes, whereby the capacitance of the capacitor changes and the voltage in the electric circuit changes. In this case, it is considered that the electric signal generator is composed of the part of the capacitor of the detection part that constitutes one electrode plate and the part that generates the electric signal according to the change of the electric charge stored in the capacitor. be able to. A signal processing unit mainly composed of a detector for detecting voltage, current, etc. as an electric signal generated by the electric signal generating unit, and a computer for acquiring a rotation speed based on a change in the electric signal detected by the detector It can be considered that the rotation speed calculation device is configured by the above, and this rotation speed calculation device can also be considered as a component of the rotation speed sensor. Further, the detection body and the detection target may be provided in a state of being rotatable relative to each other, and the detection body may be rotated, the detection target may be rotated, or both may be rotated. Since the detection body has the electric signal generator, it is desirable that the detection body is attached to the non-rotating body for the convenience of transmission of the electric signal, but the detection body may be attached to the rotating body. In the latter case, the electric signal can be transmitted to the non-rotating body by communication, or can be transmitted by the slip ring. (2) The electrical signal generation unit outputs an electrical signal corresponding to a change in the physical state of the detection unit caused by a change in the correspondence relationship between the detected unit and the detection unit in at least two locations separated from each other. The rotation speed sensor according to the item (1), which detects a change. In the rotation speed sensor described in this section,
A change in the electrical signal caused by a change in the correspondence between the detected part and the detection part at at least two locations is detected.
In the conventional rotation speed sensor, the change in the electrical signal caused by the change in the correspondence relationship at one location is detected, but in the rotation speed sensor described in this section, the correspondence at at least two locations is dealt with. Changes in the electrical signal that occur with changes in the relationship are detected. Therefore, even if at least one of the detected portion and the detection portion is eccentrically attached to the rotation center line, the influence of the eccentricity on the rotation speed can be reduced, and the relative rotation speed detection accuracy is improved. Can be made. It should be noted that a change in the electrical signal due to a change in the correspondence relationship between the detected part and the detection part at at least two locations separated from each other is detected, and a change in the electrical signal due to the change in the correspondence relationship at three or more locations is detected. Changes can also be detected. When the number of correspondences is large, the change in the electric signal due to the relative rotation can be detected more uniformly than when the number of correspondences is small, and the influence of eccentricity can be easily reduced. Further, these two positions or three or more positions may or may not be separated from each other by equal intervals.
As the rotation speed sensor of this section, for example, the one of the modes of (A) to (H) of FIG. 10 is applicable. (3) The rotation speed sensor according to item (2), wherein the at least two locations are separated from each other in the relative rotation direction of the detected portion and the detection portion. When the rotation speed is acquired based on the change in the correspondence relationship of at least two locations separated in the relative rotation direction, the rotation speed is more than that based on the change in two locations in the direction parallel to the rotation center line. The influence of eccentricity on the can be easily reduced.

(4) The rotation speed sensor according to any one of (1) to (3), wherein a plurality of the detection units are provided. (5) Each of the detection parts includes a detection member having one facing part facing the detected part, and the electric signal generating part is provided corresponding to each of the detection parts (4) The rotation speed sensor according to the item. As the rotation speed sensor described in this section, for example, (A) to (C), (E),
The form (F) is applicable. For example, the facing portion can be a protrusion formed on the body of the detection member. The protrusion may be provided so as to protrude in a direction parallel to the rotation center line of the detection member main body, or may be provided so as to protrude in a direction intersecting the rotation center line. . In some cases, the detection unit does not include the detection member having the facing portion. For example, if the detected part has unevenness on the outer peripheral surface, and if a coil is provided close to it, the inductance of the coil will be changed by the unevenness, and the current or voltage of the electric circuit will be changed accordingly. However, in this case, the detection unit includes the coil as the electric signal generation unit and does not include the detection member. (6) One or more detection sections are provided, each of the detection sections includes a detection member having at least two facing sections facing the detected section, and the electrical signal generating section includes the detection section. (1) which is provided corresponding to each of the above-mentioned ones and generates an electric signal according to a change in the physical state of the detection part according to a change in the relative relationship between the detected part and the at least two facing parts. A rotation speed sensor according to any one of items (4) to (4). For example, (D), (G),
The form (H) is applicable.

The conventional rotation speed sensor is provided with only one detecting portion, and the detecting portion includes one detecting member having one facing portion and an electric signal generating portion. Therefore, the change in the correspondence between the detected portion and the detection portion at one location due to the relative rotation is detected. On the other hand, in the rotational speed sensor described in the paragraphs (5) and (6), either one of a plurality of detecting portions is provided, or a plurality of facing portions is provided in the case of one detecting portion. is there. In any case, the detection unit is configured to be capable of detecting a change in the correspondence relationship at two or more locations due to the relative rotation between the detection target unit and the detection unit. The detection unit may include one detection member or may include two or more detection members. For example, as shown in [Embodiment of the Invention], there may be a case where one electric signal generator is provided between a pair (two) of detection members. The electrical signal generator is provided corresponding to the detector, and one detector is provided for each detector. One detection member may be provided with one facing part (A, B, C, E, F) or may be provided with two or more facing parts (D, G, H). There are two facing parts for one detection member.
When one or more are provided, two or more correspondence changes are combined, whereby the physical state of one detection unit is changed, and an electric signal corresponding thereto is generated by one electric signal generation unit. . In addition, even when only one facing portion is provided for one detection member,
If a plurality of detectors (electrical signal generators) are provided, it is possible to detect changes in the correspondence relationship at two or more locations. When a plurality of detecting units (electrical signal generating units) are provided, a change in each electric signal of the plurality of electric signal generating units is detected separately (A to D), and a combined detection is performed. In some cases (E, F, H). Further, as shown in (G), when the main body of the detection member has a generally disk shape and the outer peripheral portion includes a plurality of facing portions, the facing portions have a center angle of 180 degrees around the rotation center line. ° intervals, 120 ° intervals,
They may be provided at relatively large intervals such as 90 ° intervals or at small intervals such as 1 ° intervals and 5 ° intervals. The smaller the central angle between adjacent facing portions, the greater the number of facing portions formed. Further, the facing portion can be formed collectively (biased) in a partial region of the detection member main body (for example, a region defined by a certain center angle with reference to a straight line), but the entire circumference (center angle) It is desirable to form it over 360 °. If it is formed over the entire circumference, it is convenient to eliminate the influence of eccentricity on the rotation speed.

(7) In the paragraphs (2) to (4), including an electric signal individual detecting section for simultaneously and separately detecting the periodic change of the electric signal caused by the change of the correspondence relationship of the at least two locations. The rotation speed sensor described in any one of the above. A change in the electric signal caused by a change in the correspondence relationship between at least two locations of the detected portion and the detection portion is simultaneously and separately detected. In the rotation speed sensor described in this section,
At least two electric signal generators are provided, and they are provided in a state where they can individually generate electric signals according to changes in the physical state of the detector according to changes in the correspondence relationship at at least two locations. The electric signal individual detection unit simultaneously and separately detects changes in the electric signals generated by these electric signal generation units. If the at least two electric signal generators are provided in such a manner that the phases of the changes in the electric signals generated in the respective parts are different from each other, based on the changes in the at least two electric signals, the detected part and the detected part are detected. It is also possible to detect the direction of relative rotation with respect to the unit. In this case, the electric signal individual detection unit can be referred to as a rotation direction detection unit. For example, the rotation speed sensor in the modes of (A) to (D) of FIG. 10 is applicable. (8) In any one of the items (2) to (4), including an electric signal synthesis detection unit that also detects a periodic change in an electric signal caused by a change in the correspondence relationship of the at least two locations. The rotation speed sensor described. The combined detection unit also detects a change in the electrical signal that occurs due to a change in the correspondence relationship between at least two locations of the detected portion and the detection portion. In the rotation speed sensor described in this section, the electric signal generator is
The change of the physical state of the detection unit caused by each change of the correspondence relationship at least at two positions is combined, and the electric signal is generated in the state of generating the electric signal according to the change of the combined physical state. According to a case where a change in the electric signal generated by the electric signal generating section is detected, and the electric signal generating section responds to a change in the physical state of the detecting section associated with each change in the correspondence relationship of at least two locations. It may be provided in a state of generating an electric signal, and the electric signals may be combined and detected by the electric signal combination detection unit. For example, (D) and (E) of FIG.
The form (H) is applicable. The mode (D) can be considered to include both the electric signal synthesis detection unit and the electric signal individual detection unit. The electric signals detected by the electric signal synthesis detection unit are individually detected. According to this aspect, the influence of eccentricity can be reduced, and the relative rotation direction can be detected.

(9) In any one of the items (1) to (8), wherein the detected part and the detection part are provided symmetrically with respect to a straight line orthogonal to the rotation center line. The rotation speed sensor described. If the detection part and the detection part are provided symmetrically with respect to a straight line orthogonal to the rotation center line, at least one of the detection part and the detection part is eccentrically attached to the rotation center line, Since the influence of eccentricity on the rotation speed can be reduced, the rotation speed can be accurately detected. In this case, it means that the detected part and the detection part are symmetrical with respect to a straight line orthogonal to the rotation center line when viewed from a direction parallel to the rotation center line.
For example, the cases of the modes of (A) to (H) of FIG. 10 are applicable. (10) The shape of the detected part and the shape of the detected part are respectively symmetrical with respect to the straight line, and one of the detected part and the detected part has an annular shape, and the other is The rotation speed sensor according to any one of (1) to (9), which has a disk shape. If the shape of the detected portion and the shape of the detection portion are symmetrical with respect to a straight line, it is possible to detect the change in the correspondence relationship due to the relative rotation evenly. For example, (C), (D), (G), (H) in FIG.
The above-mentioned embodiment is applicable. (11) The rotation speed sensor according to any one of (1) to (10), wherein the detected part and the detection part are provided in axial symmetry with the rotation center line as a symmetry axis. In the rotation speed sensor described in this section, the facing portions are provided at intervals spaced from each other by the same center angle about the rotation center line. For example, (B) to (D) and (F) of FIG.
The form (H) is applicable. (12) The detected part and the detection part are concentrically provided (1)
The rotational speed sensor according to any one of items (11) to (11). In the rotation speed sensor described in this section, both the detected part and the detection part are provided concentrically. The detected part and the detection part are
There are a case where they are mounted in a direction parallel to the rotation center line, and a case where they are mounted in a direction orthogonal to the rotation center line, that is, in a radial direction. For example, the mode of (G) of FIG. 10 corresponds.

(13) The electric signal generating section cyclically changes an electric signal based on a change of a magnetic field associated with the relative rotation in a magnetic circuit including the detected section and the detecting section. (1) or (1
The rotation speed sensor according to any one of items 2). In the rotation speed sensor described in this section, the magnetic field in the magnetic circuit is periodically changed with the relative rotation between the detected portion and the detection portion. At least one of the strength and the direction of the magnetic field in the magnetic circuit is periodically changed, and the electric signal of the electric signal generator is changed accordingly. For example, the magnetic resistance is changed by changing the size of the gap between the detected part and the detection part, and the strength of the magnetic field is changed accordingly, or the magnetic resistance is opposed to each other as described later. The direction of the magnetic field can be changed by changing the magnetic poles. In this case, a magnetic circuit including the detected part and the detected part is formed in the detected part and the detected part, and the magnetic field of the magnetic circuit is periodically changed in accordance with the relative rotation thereof. It is provided in the state. The materials and shapes of the detected part and the detection part, their relative positions, and the like are designed so as to satisfy the above-mentioned conditions. Specifically, in the state where the detected part has a magnetomotive force part, the detecting part has a magnetic path forming part, and a magnetic circuit is formed including the magnetomotive force part and the magnetic path forming part,
The detected part and the detection part may be provided. The magnetomotive force part may have a permanent magnet or the like, or may have an electromagnet such as a coil. The magnetic path forming portion may be made of a magnetic material.

(14) The rotational speed sensor according to item (13), wherein the detected portion has a plurality of magnet portions provided along the relative rotation direction around the rotation center line. In the rotation speed sensor described in this section, the detected portion can be referred to as a magnet assembly. (15) The rotation speed according to the item (14), wherein the plurality of magnet portions are provided in a state where the same magnetic poles appear at predetermined intervals along the relative rotation direction at one end of the detected portion. Sensor. The plurality of magnet portions can be provided, for example, in a predetermined phase (positions separated by equal center angles) in the same direction (a state in which one end has the same pole). If it is detected that the facing portion of the detecting portion faces at least the same magnetic pole of the magnet portion of the detected portion, the relative rotation speeds of these can be detected. The plurality of magnets can be provided in a state where the magnetic poles periodically change in the relative rotation direction at one end, but the present invention is not limited to this. Further, a non-magnetic part may be provided between the two magnet parts. It is also possible to provide the magnet portions and the non-magnetic portions in a state where they are alternately positioned. In any case, in the detected part, when the number of magnet parts in the relative rotation direction is large, the change period of the electric signal can be shortened and the rotational speed detection accuracy can be improved as compared with the case where the number is small. For example, the modes (I) to (K) of FIG. 11 are applicable. (16) The detection unit is provided so as to face the same magnetic pole of the plurality of magnet units of the detected unit at a predetermined relative rotational position between the detected unit and the detected unit. The rotational speed sensor according to item (14) or (15), which includes a plurality of magnetic pole facing portions provided. The detection part includes a plurality of magnetic pole facing parts. The magnetic pole facing portion may be, for example, a protrusion provided so as to protrude from the detecting portion toward the detected portion. The protrusion may be provided so as to project in a direction parallel to the rotation center line, or may be provided so as to project in a direction orthogonal to the rotation center line. Further, even if the magnetic pole facing portions are provided so as to face all of the same magnetic poles of the magnet portion of the detected portion, every other magnetic pole facing portion, or every two magnetic pole facing portions having the same magnetic pole, is provided. It may be provided. For example,
The ones of the modes (O) and (P) of FIG. 11 correspond to this. (17) The detection unit includes a detection member having the plurality of magnetic pole facing portions, and a magnetic force line collecting unit provided in the detecting member, and the electric signal generating unit faces the magnetic force line collecting unit. The rotation speed sensor according to item (16), which is provided and whose electric state is changed according to a change in a magnetic field in the magnetic circuit. If the magnetic force line collecting portion is provided, the magnetic force lines in the magnetic circuit formed through each of the plurality of magnetic pole facing portions can be collected. If the electric signal generating section is provided so as to face the magnetic force line collecting section, even if the magnetic flux of the magnetic circuit provided corresponding to one magnetic pole facing section is small, the magnetic field applied to the electric signal generating section can be reduced. Can be large. Further, even if the magnitude of the magnetic charge of the magnet portion corresponding to the magnetic pole facing portion varies, the rotation speed can be accurately detected. The magnetic force line collecting portion is preferably provided at a position equidistant from the plurality of magnetic pole facing portions of the main body of the detection member, for example.

(18) The magnet portion has N and S magnetic poles at both ends in either a direction parallel to the rotation center line or a direction orthogonal to the rotation center line (14). The rotational speed sensor according to any one of (1) to (17). For example, the mode of (L) of FIG. 11 is a state having N pole and S pole at both ends in the direction parallel to the rotation center line, and the mode of (M) is at both ends in the direction orthogonal to the rotation center line. It has a magnetic pole. Further, the mode (M) is a state in which magnetic poles are provided at both ends in the radial direction (radiation direction about the rotation center line), and although not shown, magnetic poles are provided at both ends in the tangential direction (rotation direction). It can also be in a state. It should be noted that an example of the detected body and the detected body in the case where the detected portion is in the form of (L) is shown in FIG.
(S), (U), and (V), and an example thereof is shown in (T) in the case where the object to be detected has the form of (M). (19) The detection unit includes a first magnetic path forming member having a first magnetic pole facing portion facing one magnetic pole of the detected portion, and a second magnetic pole facing portion facing the other magnetic pole. A magnetic field change including two magnetic path forming members, wherein the electric signal generating section is provided between the first and second magnetic path forming members and generates an electric signal due to a change in the magnetic field in the magnetic circuit. The rotation speed sensor according to any one of (13) to (18), which includes a detection body. In the rotational speed sensor according to the present aspect, a pair of first and second magnetic path forming members are provided so as to face each other, and an electric signal generator is provided between the first and second magnetic path forming members. . The electric signal is changed due to the change in the magnetic field applied to the electric signal generator. The two first and second magnetic path forming members are often provided in a state of facing each other in the direction parallel to the rotation center line, but the present invention is not limited thereto. The first and second magnetic path forming members are one mode of the detecting member.

(20) The rotation speed according to any one of items (1) to (19), which includes an eccentricity influence reducing portion for reducing the influence of eccentricity in relative rotation between the detected portion and the detection portion. Sensor. (21) The rotation speed sensor according to any one of (1) to (20), which includes a rotation direction unit that acquires the direction of relative rotation between the detected part and the detection part. (22) A plurality of the detection units are provided, and the electric signal generation unit is provided in a state in which the phases of changes in the electric signals are different corresponding to the plurality of detection units, respectively.
The rotation speed sensor according to any one of items (1) to (21). According to the rotation speed sensor described in this section, it is possible to detect not only the relative rotation between the detected portion and the detection portion but also the direction of the relative rotation.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a case where a rotation speed sensor according to an embodiment of the present invention is applied as a wheel speed sensor for detecting a rotation speed of a vehicle wheel will be described in detail with reference to the drawings. In this embodiment, the wheel speed sensor is attached to the non-driving wheels. In FIG. 4, a hub wheel 8 is fixed to a wheel (wheel) 10 holding a tire by a hub bolt 12. The hub wheel 8 is attached to the wheel 10 so as not to rotate relative to the wheel 10, and the hub wheel 8 and the wheel 10 are integrally rotated about the rotation center line L. The hub wheel 8 is mounted on the axle housing 16 fixed thereto by a bearing 18 so as to be relatively rotatable. The axle housing 16 is a vehicle body side member and is a non-rotating member. A wheel speed sensor 20 is attached between the wheel shaft 14 and the axle housing 16 to detect the relative rotation speed of the wheel 10 with respect to the vehicle body member 16.

The wheel speed sensor 20 includes a detected part 30 which is a rotating body, a detecting part 32 which is a non-rotating body, and an electric circuit which detects a change in an electric signal due to rotation of the detected part 32 of the detected part 30. And a signal detection device 34. Detection unit 3
2 has an electric signal generator 35 (see FIG. 1) whose physical state is changed in accordance with these relative rotations and generates an electric signal corresponding to the physical state. Electricity generated by the electric signal generator 35 is shown in FIG. The change in the signal is detected by the electric signal detecting device 34. The electric signal detected by the electric signal detection device 34 is supplied to the calculation unit 36, and the rotation speed is calculated by the calculation based on the change of the detected electric signal. The detected part 30 is attached to the wheel shaft 14 so as not to be relatively rotatable, and the detection part 32 is attached to the axle housing 16 so as not to be relatively rotatable. The detected part 30 and the detected part 32 are provided in a state in which the detected part 30 is located on the outer peripheral side and the detected part 32 is located on the inner peripheral side in the radial direction at the same position in the direction parallel to the rotation center line L. To be

In the present embodiment, the detected part 30 is
The magnet assembly 30 can be referred to as a magnet rotor. The magnet assembly 30, as shown in FIGS.
A plurality of magnets 30a, b, 31a, 31b, which are generally annular and extend in a direction parallel to the rotation center line L.
···including. The magnet portions 30a, 31a, ... Have an N pole at one end in the direction parallel to the rotation center line L and an S pole at the other end, and the magnet portions 30b, 3a.
1b has an S pole at one end and an N pole at the other end. In the magnet assembly 30, at one end portion in the direction parallel to the rotation center line L, the N pole, S and S are arranged along the relative rotation direction around the rotation center line L.
The poles, the N poles, etc. are alternately located, and the other end has a S pole (corresponding to the N pole at one end) along the relative rotation direction.
The N poles, the S poles, etc. are alternately located (corresponding to the S poles at one end). At both ends in the direction parallel to the rotation center line L, the same magnetic poles (which become opposite poles at both ends) are located at the same intervals. The magnet assembly 30 can be formed, for example, by mixing resin with magnetic powder and magnetizing the magnetic powder in a state where the magnetic poles are reversed along the relative rotation direction.
A plurality of bar magnets extending in a direction parallel to the rotation center line L has a form similar to that arranged along the relative rotation direction.

The detector 32 detects the rotational speed of the magnet assembly 30, and is located between the yokes 37 and 38 as a pair of detection members facing the magnet assembly 30 and between the pair of yokes 37 and 38. And a Hall element 35 as an electric signal generator provided. The yokes 37 and 38 are made of a magnetic material,
That is, it is formed of a magnetic path forming member, and generally has a disc shape. A pair of yokes 3
7, 38 are provided in a state of facing each other with a direction parallel to the rotation center line L separated. A plurality of protrusions 42 and 44 as magnetic pole facing portions are provided on the outer peripheral portions of the main bodies of the yokes 37 and 38, respectively. The protrusions 42 and 44 are evenly provided over the entire circumference of the yoke main body at regular intervals, that is, in a state in which they are located in a predetermined phase. As shown in FIG. Protrusion 42 on the yoke 37
Is the same as the spacing of the protrusions 44 in the yoke 38, and they are mounted in the state of being in the same phase.

The yoke 37 is provided close to the inner peripheral surface of one end of the magnet assembly 30 at the projection 42, and the yoke 38 is provided at the projection 44 at the other end of the magnet assembly 30. It is provided close to the peripheral surface. The magnetic poles facing the plurality of protrusions 42 are all the same, and the magnetic poles facing the plurality of protrusions 44 are also the same. Further, as described above, in the magnet assembly 30, the rotation center line L
Since the magnetic poles are opposite at one end and the other end in the direction parallel to, the magnetic pole facing the protrusion 42 and the magnetic pole facing the protrusion 44 are opposite.

FIG. 2 shows a state in which one of the protrusions 42, 44 of the yokes 37, 38 faces the magnet portion 30b of the magnet assembly 30. In this state, all the protrusions 42 face the south pole and all the protrusions 44 face the north pole. In the vicinity of the rotation center line L at the central portions of the yokes 37 and 38, protrusions 46 and 48 as magnetic force line collecting portions that protrude in parallel with the rotation center line L and that face each other are provided. The hall element 35 is provided between 46 and 48. The magnetic force line collecting portions 46 and 48 are provided at positions substantially equidistant from the plurality of magnetic pole facing portions 42 and 44 of the yokes 37 and 38. In the state shown in FIG. 2, the magnet assembly 30,
A magnetic circuit R reaching the yoke 37, the hall element 35, the yoke 38, and the magnet assembly 30 is formed. In the magnetic circuit R, the magnet assembly 30 serves as a magnetomotive force portion, and the yokes 37, 3
8 is a magnetic path forming portion. As described above, in this embodiment, the magnet assembly 30 and the pair of yokes 37 and 38 are
An annular magnet assembly 30 is located concentrically with respect to the rotation center line L on the outer peripheral side, and has a generally disk-shaped yoke 3
7, 38 are provided in a state of being located on the inner peripheral side. Also,
The shapes of the magnet assembly 30 and the pair of yokes 37, 38 are symmetrical with respect to the straight line M orthogonal to the rotation center line L, and are also symmetrical when the rotation center line L is an axis of symmetry.

The Hall element 35 is made of a semiconductor and generates an electric signal according to the change of the magnetic field in the magnetic circuit to be formed. As shown in FIG. 3, the Hall element 35 is supplied with a constant current in a constant direction. In this state, when a magnetic field is applied in a direction perpendicular to the direction in which the current flows, the direction in which the current flows is bent by this, and a voltage is generated in a direction orthogonal to both the direction of the current and the direction of the magnetic field. The magnitude of the voltage depends on the product of the strength of the magnetic field and the magnitude of the current. The vector of voltage depends on the vector product of the current and the magnetic field. The magnetic field is the yoke 3
The direction is opposite between the case where 7 faces the N pole and the yoke 38 faces the S pole, and the case where the yoke 37 faces the S pole and the yoke 38 faces the N pole. The direction of the magnetic field applied to the Hall element 35 is changed, and the direction of the voltage is changed. As described above, the Hall element 35 has its electrical state changed due to the change of the magnetic field, and the voltage is changed accordingly, and this voltage is detected by the voltmeter 34 as an electric signal detection device. To be done. It is desirable that the voltmeter 34 be capable of detecting the direction of the voltage. The wheel speed sensor 20 in the present embodiment corresponds to the mode (S) in FIG.

The wheel speed sensor 2 constructed as described above
0, the magnet assembly 3 is rotated as the wheel 12 rotates.
0 is rotated. As the magnet assembly 30 rotates, the magnetic poles of the magnet assembly 30 where the protrusions 42 and 44 face each other change, and the direction of the magnetic field applied to the Hall element 35 changes. Thereby, the direction of the voltage changes periodically, but the voltage is detected by the voltmeter 34. Voltmeter 34
The rotation speed of the wheel 12 is detected by the calculation unit 36 based on the change in the voltage detected by the. It can be considered that the rotation speed is higher when the voltage change cycle is shorter than when the voltage change cycle is long.

As described above, in this embodiment, since the protrusions 42 and 44 are provided in the entire direction of rotation of the yokes 37 and 38, in the Hall element 35, an average magnetic field of these is applied. Become. Therefore, at least one of the magnet assembly 30 and the detection unit 32 has a rotation center line L.
Even if it is eccentrically provided, the influence of the eccentricity on the rotation speed can be reduced, and the wheel speed can be accurately detected. In addition, the magnet parts 30a, b, 31
a, b ... Even if the strength (magnetic charge) of each magnetomotive force varies, the influence thereof can be reduced. Further, since the magnetic force line collecting portions 46 and 48 are provided in substantially the central portions of the yokes 37 and 38, even if the magnetic field strength in the magnetic circuit formed corresponding to one protrusion 42, 44 is small, these The magnetic field collected and applied to the Hall element 35 can be strengthened. The change in the electrical state of the hall element 35 can be increased, and the change in the electric signal can be increased.

In the above embodiment, in the magnet assembly 30, the magnet parts 30a, b, 31a, b ...
At both ends in the direction parallel to the rotation center line L, respectively.
Although the pole and the S pole were provided in the position,
As shown in FIG.
0a, b ... Can be provided in a direction orthogonal to the rotation center line L, and in a state where the N pole and the S pole are respectively located at both ends in the radial direction. Magnet assembly 100
Is in a direction orthogonal to the rotation center line L and has a form similar to that in which a plurality of bar magnets extending in the radial direction are arranged. The magnet portion 100a has an N pole at the end on the inner peripheral side and an S pole at the end on the outer peripheral side, and the magnet portion 100b has an S pole at the end on the inner peripheral side.
It has a pole and has an N pole at the end on the outer peripheral side.

Similar to the case of the above embodiment, the pair of yokes 102 and 104 are provided in a state of being separated from each other in a direction parallel to the rotation center line L and facing each other.
The yoke 102 is generally in the shape of a disk, and the protrusion 106 protruding toward the outer circumference is provided in a state of facing the end surface on the inner circumference side of the magnet assembly 100, and the yoke 104 is generally in the shape of a bottomed cylinder. The protrusion 108, which protrudes from the cylindrical portion of the magnet assembly 100 toward the inner peripheral side, is provided so as to face the outer peripheral end surface of the magnet assembly 100. A protrusion 110 as a magnetic force line gathering portion is provided so as to project from the central portion of the body of the yoke 102 (a flat plate portion of the circular plate), and a protrusion 112 as a magnetic force line gathering portion is provided so as to project from the bottom portion of the body of the yoke 104. Is provided. These magnetic force line collecting portions 110, 11
The Hall element 35 is attached between the two. In Figure 6,
The protrusion 106 of the yoke 102 faces the south pole,
4 shows a state in which the protrusion 108 of No. 4 faces the north pole. The wheel speed sensor in this embodiment corresponds to the mode (T) in FIG. Also in the present embodiment, as in the case of the above-described embodiment, the rotation speed is detected based on the change state of the voltage generated in the Hall element 35.

As shown in the mode (U) of FIG.
In the yokes 130 and 132, the magnetic pole facing portions 134 and 1
The magnet assembly 36 may be formed on the same circumference as the magnet assembly 30. In this case, the plurality of magnetic pole facing portions 134 and 136 are connected to the yokes 130 and 132.
It is provided in a state of protruding substantially perpendicularly (in a direction parallel to the rotation center line) to the disc portion which is the main body of the. Further, as shown in the mode (V) of FIG. 12, the yokes 140 and 142 are
At the magnetic pole facing portions 144 and 146,
It can be formed so as to face the outer peripheral surface of 0. The yokes 140 and 142 are annular and are provided on the outer peripheral side of the magnet assembly 30, and the magnetic pole facing portions 144 and 146 are provided so as to project toward the inner peripheral side. In this case, the magnet assembly 30 may be attached to the non-rotating body and the yokes 140 and 142 may be attached to the rotating body. It should be noted that although the protrusions 147 and 148 as magnetic force line collecting portions are not provided at positions equidistant from the plurality of magnetic pole facing portions 144 and 146, the magnetic field applied to the Hall element 35 is made stronger than in the case where they are not provided. be able to.

Further, as shown in the mode (X) of FIG.
In the yokes 150 and 152, the magnetic pole facing portions 154 and 1
56 may be formed so that every other one of the plurality of magnet parts of the magnet assembly 30 having the same magnetic pole faces each other. In this case, the gap between the magnetic pole facing portions becomes larger than that in each of the above embodiments. In this case, the yokes 150 and 152 may be attached such that the magnetic pole facing portions 154 and 156 have different phases. The magnetic pole facing portions may be formed in the case where a plurality of magnet portions having the same magnetic pole of the magnet assembly 30 face each other.

Further, the rotation speed sensor may be provided with two or more detecting portions. For example, if the two detection units are provided in a state in which the phases of changes in voltage in the Hall elements are different, not only the rotation speed of the wheel 12 but also the rotation direction can be detected. 7 and 8
In the rotation speed sensor shown in FIG.
2, a detection unit (yoke pair) 203, a yoke 204,
A detection unit (yoke pair) 207 including 206 is provided. The detection unit 203 and the detection unit 207 are provided in a symmetrical state with respect to a straight line M orthogonal to the rotation center line L. In the relative positional relationship shown in FIG.
2, the protrusion 210 of the yoke 200 faces the N pole at one end in the direction parallel to the rotation center line L of the magnet assembly 30, and the protrusion 212 of the yoke 202 becomes the S pole at the other end. opposite. These yokes 200, 2
02, each of the projections 21 as a magnetic force line assembly is located at a position substantially equal to the projections 210 and 212.
4, 216 are provided, and these magnetic force line collecting portions 214, 2 are provided.
A Hall element 218 is provided between the sixteen. Detector 20
7, the protrusion 224 provided on the yoke 204 faces the N pole and the S pole at one end in the direction parallel to the rotation center line L of the magnet assembly 30, and the protrusion 226 provided on the yoke 206 is , The other end faces between the S pole and the N pole. Also in the detection unit 207, the yokes 204, 20
The Hall element 232 is provided between the magnetic force line collecting portions 228 and 230 provided in FIG.

The voltage of the Hall element 218 is detected by the voltmeter 234, and the voltage of the Hall element 232 is detected by the voltmeter 23.
Detected by 6. These output signals are calculated by the calculation unit 36.
Is supplied to. FIG. 9 shows the state of changes in voltage detected by the voltmeters 234 and 236, respectively. In the state shown in FIG. 8, the magnetic circuit R is formed in the detection unit 203. The Hall element 218 is applied with a magnetic field in the direction from the yoke 200 to the yoke 202 (here, in the positive direction. In FIG. 9, the magnetic field of the yoke 200 is described as N). No magnetic circuit is formed in the detection unit 207. When the magnet assembly 30 is rotated from this state, the Hall elements 218, 23
Although the voltage applied to 2 changes, the detection unit 20
3, the direction of the magnetic field applied to the Hall element 218 is reversed regardless of whether the magnet assembly 30 rotates in the direction of arrow P or the direction of arrow Q, and the yoke 200 is moved from the yoke 202 side.
It becomes the direction toward the side (here, the negative direction).
On the other hand, in the detecting unit 207, when rotating in the direction of arrow P, the magnetic field in the positive direction is applied, but when rotating in the direction of arrow Q, the magnetic field in the negative direction is applied. Therefore, based on both of these changed states, not only the rotation speed of the magnet assembly 30 but also the rotation direction can be detected.

Further, the electric signal generating section is not limited to the Hall element, but may be a magnetoresistive element or a coil. The electrical state may be changed due to the change of the magnetic field due to the relative rotation of the magnet assembly and the yoke. Also, the electric signal generator may change its electrical state due to a change in capacitance, or may change its electrical state due to a change in light receiving state. You can also

Furthermore, the present invention relates to the embodiment (A) of FIG.
It can be applied to the rotation speed sensor shown in (B), (E), and (F). It can be applied to a so-called electromagnetic pickup type rotation speed sensor, a rotation speed sensor having a light receiving element, and the like. For example, the mode (A) of FIG.
In the rotational speed sensor shown in FIG. 3, a rotor 300 as a detected portion having an outer peripheral surface formed with irregularities is rotatably held integrally with the wheel 12, and detection portions 306 and 308 each including a coil are provided in the axle housing 16. It is mounted so that it cannot rotate relative to it. Two detectors 306 and 308
Are attached at positions separated in the rotation direction of the rotor 300. The current flowing through the coils of the detectors 306 and 308 is
The rotation speeds are detected by the ammeters 310 and 312, respectively, and the rotation speed is detected based on the change in each current.
The detection units 306 and 308 may be configured by coils or may be configured by coils and iron cores. If the rotor 300 is provided eccentrically with respect to the rotation center line L, the ammeter 31
The change state of the current detected by 0 and 312 differs, but the change state of these currents and the detection units 306 and 308 are different.
, The influence of eccentricity on the rotation speed can be reduced. In addition, the detection unit 30
If 6 and 308 are provided in a state where the phases of changes in these electric signals are different, it is possible to detect the rotation direction of the rotor 300. As shown in the mode (B),
It is also possible to provide three or more detectors. Although the plurality of detectors can be provided at equal intervals,
Not limited to that. If the relative phases of the plurality of detectors are known, it is possible to detect the changes in the respective electric signals in a superimposed manner, as shown in modes (E) and (F).

Besides, the present invention can be implemented in various modes shown in FIGS. Further, the invention is not limited to the rotation speed of the wheels of the vehicle, and can be widely applied to a sensor that detects the rotation speed of the rotating body with respect to the non-rotating body. Since the present invention can be carried out in the modes described in [Problems to be solved by the invention, means for solving the problems and effects], various modifications and improvements based on the knowledge of those skilled in the art is there.

[Brief description of drawings]

FIG. 1 is a diagram (perspective view) conceptually showing a rotation speed sensor that is an embodiment of the present invention.

FIG. 2 is a sectional view of the rotation speed sensor.

FIG. 3 is a diagram illustrating a principle of an electric signal generating unit of the rotation speed sensor.

FIG. 4 is a diagram showing a state in which the rotation speed sensor is attached.

FIG. 5 is a diagram conceptually showing a magnet assembly of a rotation speed sensor which is another embodiment of the present invention.

FIG. 6 is a cross-sectional view of the rotation speed sensor.

FIG. 7 is a view (front view) conceptually showing a rotation speed sensor that is another embodiment of the present invention.

FIG. 8 is a cross-sectional view of the rotation speed sensor.

FIG. 9 is a diagram showing a change state of an output signal of a voltmeter in the rotation speed sensor.

FIG. 10 is a diagram showing various aspects of a rotation speed sensor that is an embodiment of the present invention.

FIG. 11 is a diagram showing various aspects of a rotation speed sensor that is an embodiment of the present invention.

FIG. 12 is a diagram showing various aspects of a rotation speed sensor that is an embodiment of the present invention.

[Explanation of symbols]

20 wheel speed sensor 30, 100 magnet assembly 32, 203, 207, 306, 308 detector 34, 234, 236 voltmeter 37, 38, 102, 104, 130, 132, 14
0,142,150,152,200,202,20
4,206 Yoke 35,218,232 Hall element 42,44,106,108,134,136,14
4,146,154,156,210,224 Protrusions 46,48,110,112,214,216,22
8,230 Magnetic force collecting unit 300 Rotor 310, 312 Ammeter

Claims (7)

[Claims] 1. A detection unit and a detection unit, which are arranged close to each other and are rotatable relative to each other around a rotation center line,
And, the detection unit, at least, an electric signal generating unit for generating an electric signal corresponding to the change in the physical state of the detection unit due to relative rotation of the detection unit and the detected portion, from the electric signal generation unit A rotation speed sensor for detecting the speed of the relative rotation based on a change in an electric signal, wherein the electric signal generating section has a correspondence relationship between at least two locations where the detected section and the detection section are separated from each other. A rotation speed sensor, which generates an electric signal corresponding to a change in a physical state of the detection unit caused by a change. 2. The rotation speed sensor according to claim 1, wherein the rotation speed sensor is provided symmetrically with respect to a straight line orthogonal to the rotation center line. 3. The electric signal generating section outputs an electric signal which periodically changes due to a change in a magnetic field associated with the relative rotation in a magnetic circuit formed including the detected section and the detecting section. The rotation speed sensor according to claim 1 or 2, which is generated. 4. The detected part has a plurality of magnet parts provided along the relative rotation direction around the rotation center line, and the detected part preliminarily includes itself and the detected part. 4. The magnetic pole facing section according to claim 1, further comprising a plurality of magnetic pole facing sections that respectively face ones of the plurality of magnet sections of the detected section having the same magnetic pole at a determined relative rotation position. Rotation speed sensor. 5. The magnet part has N and S magnetic poles at both ends in one of a direction parallel to the rotation center line and a direction orthogonal to the rotation center line. The rotation speed sensor described in. 6. A first magnetic path forming portion, wherein the detecting portion has a first magnetic pole facing portion facing one magnetic pole of the detected portion,
A second magnetic path forming portion having a second magnetic pole facing portion facing the other magnetic pole, wherein the electric signal generating portion includes the first and second magnetic path forming portions.
The rotation speed sensor according to claim 4, further comprising a magnetic field change detection unit that is provided between the second magnetic path formation units and that generates an electric signal due to a change in an acting magnetic field. 7. A plurality of the detection units are provided, and the electric signal generation unit is provided in a state in which the phases of changes in the electric signals are different corresponding to the plurality of detection units, respectively. 7. The rotation speed sensor according to any one of items 1 to 6.