JP3413596B2 - Rotation sensor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called two-pole type rotation sensor for detecting the rotation speed of a rotating body.

[0002]

2. Description of the Related Art Conventionally, a two-pole type rotation sensor for detecting the rotation speed of a rotating body has been disclosed in Japanese Utility Model Laid-Open No. 61-14982.
It is known from Japanese Patent No. 2 publication.

The rotation sensor (gear sensor) disclosed in the above publication has a U-shaped configuration in which an iron core around which a coil is wound is arranged at one end of two magnetic poles facing each other. The permanent magnet is sandwiched between the intermediate portions, and the voltage induced in the coil can be detected based on the magnetic substance passing through the other end of the magnetic yoke.

[0004]

However, since the two-pole type rotation sensor has directivity, the two-pole type rotation sensor has two directions with respect to the rotating direction of the magnetic body, that is, the moving direction of the peripheral portion of the magnetic body (rotating body portion). It is necessary to match the facing directions of the two magnetic poles. Therefore, when the sensor main body is installed, it is necessary to perform accurate positioning, and if the positioning is not performed accurately, problems such as a decrease in voltage induced in the coil and disturbance of the detected waveform occur.

Therefore, the conventional rotation sensor using the two-pole type requires assembly accuracy (positioning accuracy),
In addition to the deterioration of the assemblability, when the positional deviation occurs due to vibration, impact, etc., the above-mentioned problems occur, and eventually there is a problem that it is difficult to maintain high detection accuracy, stability and reliability.

The present invention solves the problems existing in the prior art as described above, and provides a rotation sensor capable of improving the assembling property and always maintaining high detection accuracy, stability and reliability. To aim.

[0007]

Means for Solving the Problems and Embodiments The present invention is directed to a gear-shaped rotating body 2 formed of a magnetic material having irregularities on a peripheral portion 2s, and a sensor main body arranged close to the rotating body 2. When constructing the rotation sensor 1 including the inner pole 4, the inner pole 4 having a circular cross section and made of a magnetic material, and the cylindrical magnet 5 covering the outer peripheral surface of the inner pole 4.
And a sensor body 3 having a cylindrical outer pole 6 formed of a magnetic material that covers the outer peripheral surface of the magnet 5, and a detection coil 7 that detects a change in magnetic flux generated by the magnet 5. .

As a result, the inner pole 4 and the outer pole 6 are coaxially arranged, so that there is no phase restriction (directivity) in the circumferential direction. Therefore, even if the sensor body 3 is rotationally displaced in the circumferential direction, that is, the position shift occurs, the detection coil 7
There is no decrease in voltage or disturbance in the detected waveform that is induced in the.

In this case, according to a preferred embodiment, the sensor body 3 is provided with a coil bobbin 11 around which the detection coil 7 is wound. The coil bobbin 11 can be attached to the outer peripheral surface of the outer pole 6, and at this time, the outer pole 6
A plurality of small convex portions 11ms on the inner peripheral surface facing the outer peripheral surface of the ...
Can be provided. In addition, the coil bobbin 11 has
Wire ends 7s and 7e of the detection coil 7 and lead wires 12 and 13
Terminal mounting portion 1 having lead terminals 14 and 15 for connecting
6 can be integrally formed. On the other hand, Inner Paul 4
Can be cylindrical or cylindrical. In the case of a cylindrical shape, the detection coil 7 can be housed inside, and an axial notch 4c can be formed by an elastic material. On the other hand, the outer pole 6
Can be formed of an elastic material and can be provided with a notch 6c in the axial direction. Further, the magnet 5 can be configured by a combination of a plurality of divided magnet portions 5p ... Divided in the circumferential direction, and one or both of the inner pole 4 and the outer pole 6 can be sintered with ferromagnetic powder. A mixture of ferromagnetic powder and binder can also be compression molded. It should be noted that the sensor main body 3 is integrally provided with an external mounting portion 18 and is provided with an overmolded portion 17 that covers the entire sensor main body 3.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

First, the parts used in the rotation sensor 1 according to this embodiment will be described with reference to FIGS.

As shown in FIG. 1, the rotation sensor 1 is composed of a gear-shaped rotating body portion 2 and a sensor main body portion 3 which is arranged so as to face and be close to a peripheral portion 2s of the rotating body portion 2. The rotating body portion 2 is made of a magnetic material, and has peripheral portions 2s having concave portions 2sa ... And convex portions 2sb which are alternately formed. The rotating body 2 is attached to the rotating shaft 2x that is the detection destination.

On the other hand, in the sensor main body 3, 11 is a coil bobbin integrally molded of synthetic resin, and as shown in FIG. 4, a cylindrical bobbin main body 11m and one provided on one end of the bobbin main body 11m. Barrier part 11b
And a cylindrical terminal mounting portion 16 which also serves as the other barrier portion provided at the other end of the bobbin main body portion 11m. in this case,
The terminal mounting portion 16 has two lead terminals 14 and 15 integrally provided by insert molding. Each lead terminal 1
4, 15 are formed in an L shape, one end of which projects from the end surface of the terminal mounting portion 16, and the other end of which is located inside the housing recesses 21 and 22 provided on the peripheral surface of the terminal mounting portion 16 and extends outward from the peripheral surface. Make it protrude.

Reference numeral 4 denotes an inner pole having a columnar shape (circular cross section), which is integrally formed of a magnetic material. Reference numeral 5 denotes a cylindrical magnet that covers the outer peripheral surface of the inner pole 4, and is composed of a combination of four (generally a plurality of) divided magnet portions 5p ... Which are equally divided in the circumferential direction. As a result, the inner peripheral surface of the magnet 5 can be brought into close contact with the outer peripheral surface of the inner pole 4, and the magnetic characteristics can be improved and stabilized. The inner peripheral surface of the magnet 5 is one pole (for example, N pole), and the outer peripheral surface is the other pole (for example, N pole).
S pole). Further, 6 is a cylindrical outer pole that covers the outer peripheral surface of the magnet 5, and is integrally formed of a magnetic material. In this case, the outer pole 6 is made of an elastic material, and is provided with a notch 6c in the axial direction. As the elastic material, for example, a magnetic stainless steel material (JIS
(SUS430, etc.) and a galvanized steel sheet which is advantageous in terms of cost can be used. As a result, the inner peripheral surface of the outer pole 6 can be brought into close contact with the outer peripheral surface of the magnet 5, and the magnetic characteristics can be improved and stabilized. In addition, the inner pole 4, the magnet 5 and the outer pole 6
The axial lengths of are substantially the same.

Next, a method of manufacturing the rotation sensor 1 (sensor main body 3) according to this embodiment will be described with reference to FIGS.

First, the detection coil 7 is wound around the coil bobbin 11, and the wire ends 7s and 7e led out from the detection coil 7 are connected to the lead terminals 14 and 15 protruding from the peripheral surface of the terminal mounting portion 16 (FIG. 4). The lead terminals 14 and 15 connecting the wire ends 7s and 7e are
As shown by the phantom line in FIG. 4, it is housed in the housing recesses 21 and 22 by being bent at a substantially right angle.

The outer pole 6 and the magnet 5 are provided inside the bobbin body 11m of the coil bobbin 11.
And insert the inner pole 4. This state is shown in FIG. In this case, the outer pole 6 and the magnet 5,
The magnet 5 and the inner pole 4 need to be in close contact with each other, but the outer pole 6, the coil bobbin 11, the divided magnet portions 5p, ... Are not necessarily in close contact with each other. On the other hand, lead wires 12 and 13 are connected to the lead terminals 14 and 15 protruding from the end surface of the terminal mounting portion 16, respectively.

Next, the assembly unit manufactured through the above steps is secondarily molded. That is, by covering the entire assembly unit with synthetic resin, the overmolded portion 17
To provide. As a result, the whole becomes cylindrical. At this time, the external mounting portion 18 shown in FIG. 2 is integrally formed with the overmolded portion 17. The external mounting portion 18 allows the rotation sensor 1 to be mounted on a target portion, and
Positioning with respect to the rotating body part 2 can be performed. Therefore, the sensor main body 3 shown in FIG. 1 can be obtained.

According to the rotation sensor 1 according to this embodiment, the magnetic flux generated from the inner peripheral surface of the magnet 5 passes from the inner pole 4 to the outer pole 6 and then to the magnet 5.
To the outer peripheral surface of. On the other hand, when the rotating body portion 2 rotates, the concave portions 2sa ... And the convex portions 2sb provided on the peripheral portion 2s alternately approach the tip end surface of the sensor body portion 3, so that the rotating body portion 2
The magnetic flux changes according to the rotation of. Then, this change in magnetic flux is detected as an induced voltage in the detection coil 7.

Further, since the inner pole 4 and the outer pole 6 are arranged coaxially, phase restriction (directivity) in the circumferential direction is eliminated. Therefore, even if the sensor body 3 is rotationally displaced in the circumferential direction, that is, the position of the sensor main body 3 is displaced, the voltage drop in the detection coil 7 and the detection waveform are not disturbed. Therefore, the assemblability can be improved, and at the same time,
It is possible to maintain high detection accuracy, stability, and reliability, and it is suitable for use as, for example, a vehicle speed sensor provided in an ABS (anti-lock braking system) of an automobile.

The embodiment has been described in detail above.
The present invention is not limited to such an embodiment,
The detailed configuration, shape, material, quantity, etc. can be arbitrarily changed, added, or deleted without departing from the scope of the present invention.

For example, the magnet 5 has been shown to be composed of a combination of a plurality of divided magnet portions 5p ... Divided in the circumferential direction. However, as shown in FIG. 6, the magnet 5 may be integrally formed into a cylindrical shape. Good. At this time, if the inner pole 4 is made of an elastic material and the axial cut portion 4c is provided,
The outer peripheral surface of the inner pole 4 can be brought into close contact with the inner peripheral surface of the magnet 5, and the magnetic characteristics can be improved and stabilized. Further, if the inner pole 4 is formed in a cylindrical shape, a hollow portion is formed inside, so that the detection coil 7 is formed in this hollow portion.
Can also be accommodated. Further, the magnet 5 sinters one or both of the inner pole 4 and the outer pole 6 with a ferromagnetic powder (ferrite particles or the like) or compression-molds a mixed material of the ferromagnetic powder and a binder (synthetic resin or the like). You can also The material of the inner pole 4 can be the same as the material of the outer pole 6 described above.

On the other hand, in the embodiment, the split magnet portions 5p ...
Although the end face shape of was formed in an arc shape, as shown in FIG.
The end surface shape of the divided magnet portions 5p ... May be formed into a trapezoid. Note that FIG. 7 shows a case where the magnet 5 is divided into eight in the circumferential direction. Therefore, the circle (cylinder or cylinder) in the present invention does not mean a perfect circle, but is a concept including polygons, ellipses, and the like that can achieve the effects of the present invention to some extent.

Further, FIG. 8 shows that a plurality of small convex portions 1 are formed on the inner peripheral surface of the coil bobbin 11 facing the outer peripheral surface of the outer pole 6.
1 ms ... is provided. If formed in this way,
The small convex portions 11ms press the outer peripheral surface of the outer pole 6 toward the center by its own elasticity, so that the adhesion between the inner pole 4, the magnet 5 and the outer pole 6 can be further enhanced, and mechanical backlash can be prevented. You can
6 to 8, the same parts as those in FIG. 5 are designated by the same reference numerals to clarify the configuration thereof, and detailed description thereof will be omitted.

Further, FIG. 9 shows a so-called cross type layout configuration. In the embodiment of FIG. 1, the axis line of the inner pole 4 and the axis line of the rotating body portion 2 have a right angle relationship (different directions), but in the layout configuration of FIG. 9, the axis line of the inner pole 4 and the axis line of the rotating body portion 2 are Parallel relationship (same direction). That is, the modified embodiment shown in FIG.
Only the protrusion from the tip of the sensor main body 3
The peripheral portion 2s is opposed to the peripheral surface of the inner pole 4 protruding from the tip of the sensor body 3. Also in this case, the same effect as the embodiment of FIG. 1 can be obtained.
In FIG. 9, the same parts as those in FIG. 1 are designated by the same reference numerals to clarify the configuration thereof, and detailed description thereof will be omitted.

[0026]

As described above, the rotation sensor according to the present invention includes an inner pole having a circular cross section formed of a magnetic material,
A sensor body having a cylindrical magnet that covers the outer peripheral surface of the inner pole, a cylindrical outer pole formed of a magnetic material that covers the outer peripheral surface of the magnet, and a detection coil that detects a change in magnetic flux generated by the magnet. As a result, the following remarkable effects are achieved.

(1) By avoiding the influence of the assembly precision (positioning precision), the assemblability can be improved, and high detection precision, stability and reliability can always be maintained.

(2) According to a preferred embodiment, the coil bobbin is mounted on the outer peripheral surface of the outer pole, and
If a plurality of small convex portions are provided on the inner peripheral surface facing the outer peripheral surface of the outer pole, the outer peripheral surface of the outer pole can be pressed toward the center by its own elasticity, and the adhesion can be further improved.

(3) According to the preferred embodiment, if the magnet is composed of a combination of a plurality of divided magnet portions divided in the circumferential direction, the inner peripheral surface of the magnet can be brought into close contact with the outer peripheral surface of the inner pole. Therefore, the magnetic characteristics can be improved and stabilized.

(4) According to the preferred embodiment, if the outer pole is made of an elastic material and the notch in the axial direction is provided, the inner peripheral surface of the outer pole can be brought into close contact with the outer peripheral surface of the magnet. In addition, the magnetic characteristics can be improved and stabilized.

(5) According to a preferred embodiment, if the inner pole is made of an elastic material and provided with a notch in the axial direction, even if the magnet is integrally formed into a cylindrical shape, The outer peripheral surface of the magnet can be brought into close contact with the inner peripheral surface of the magnet, and the magnetic characteristics can be improved and stabilized.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a rotation sensor according to a preferred embodiment of the present invention,

FIG. 2 is a sectional view taken along line AA in FIG.

FIG. 3 is an exploded perspective view showing a part of an inner pole, a magnet and an outer pole of the rotation sensor,

FIG. 4 is a longitudinal sectional view showing a state before molding an overmolded portion of the rotation sensor,

5 is a sectional view taken along line BB in FIG. 4,

FIG. 6 is a cross-sectional view taken along the line AA in FIG. 1 showing a part of a rotation sensor according to a modified embodiment of the invention.

FIG. 7 is a sectional view taken along the line AA in FIG. 1, showing a part of a rotation sensor according to another modified embodiment of the present invention;

FIG. 8 is a cross-sectional view taken along the line AA in FIG. 1, showing a part of a rotation sensor according to another modified embodiment of the invention.

FIG. 9 is a longitudinal sectional view showing a part of a rotation sensor according to another modified embodiment of the present invention,

[Explanation of symbols]

1 rotation sensor 2 Rotating body 2s Rotor part circumference 3 Sensor body 4 Inner Paul 4c Inner pole notch 5 magnets 5p ... Split magnet part 6 Outer pole 6c Outer pole notch 7 Detection coil 7s Detection coil wire end 7e Detection coil wire end 11 coil bobbins 11ms ... Small convex part 12 Leader 13 Leader 14 Lead terminal 15 lead terminals 16 terminal mounting part 17 Overmolded part 18 External mounting part

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01D 5/00-5/62 G01B ⁷ /00-7/30 G01P 1/00-3/80

Claims (12)

(57) [Claims] 1. A rotation sensor comprising a gear-shaped rotating body portion formed of a magnetic material having irregularities on a peripheral portion thereof, and a sensor main body portion arranged close to the rotating body portion. A pole, a cylindrical magnet that covers the outer peripheral surface of the inner pole, a cylindrical outer pole formed of a magnetic material that covers the outer peripheral surface of the magnet, and a detection coil that detects a change in the magnetic flux generated by the magnet. A rotation sensor, comprising: a sensor main body having the sensor. 2. The rotation sensor according to claim 1, wherein the sensor body includes a coil bobbin around which the detection coil is wound. 3. The rotation sensor according to claim 2, wherein the coil bobbin is mounted on an outer peripheral surface of the outer pole. 4. The rotation sensor according to claim 3, wherein the coil bobbin has a plurality of small convex portions on an inner peripheral surface facing the outer peripheral surface of the outer pole. 5. The rotation sensor according to claim 2, wherein the coil bobbin is integrally formed with a terminal mounting portion having a lead terminal for connecting a wire end of the detection coil and a lead wire. 6. The rotation sensor according to claim 1, wherein the inner pole is formed in a cylindrical shape or a cylindrical shape. 7. The rotation sensor according to claim 6, wherein the detection coil is housed inside the cylindrical inner pole. 8. The inner pole formed in a cylindrical shape,
The rotation sensor according to claim 6 or 7, wherein the rotation sensor is formed of an elastic material and is provided with a notch in the axial direction. 9. The rotation sensor according to claim 1, wherein the outer pole is formed of an elastic material and is provided with an axial notch. 10. The rotation sensor according to claim 1, wherein the magnet is configured by a combination of a plurality of divided magnet portions divided in the circumferential direction. 11. The magnet according to claim 1, wherein one or both of the inner pole and the outer pole is made by sintering ferromagnetic powder or by compression molding a mixture of ferromagnetic powder and a binder. The rotation sensor according to 1. 12. The rotation sensor according to claim 1, wherein the sensor main body portion integrally has an external mounting portion and an overmolded portion that covers the entire sensor main body portion.