JPH08304433A - Revolution sensor - Google Patents

Abstract

PURPOSE: To largely detect an output voltage by using a torus-shaped sensor part as the sensor part for a revolution sensor and to prevent the phase shift at end-part recessed and protruding parts of two ferromegnetic rings at the sensor part by installing a positioning member. CONSTITUTION: A sensor part 12 for a revolution sensor 10 is formed in such a way that a coil 15 is wound on a bobbin 14 concentrically with a sensor rotor 11 and that the inner circumference and the outer circumference of a magnet 16 are sandwiched between two ferromegnetic rings 17a, 17b so as to be brought into contact with, and juxtaposed with, the bobbin. At least one each of protrusions 19a, 19b are formed on the inside and the outside of the bobbin 14 so that the phase shift of iregularities 18 at ends of the two ferromagnetic rings 17a, 17b is prevented so as to assemble the rings. Cutouts 20a, 20b are formed at the two ferromagnetic rings 17a, 17b. When both are fitted, the phase shift is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation sensor for detecting the number of rotations and the rotation speed of an automobile wheel or the like.

[0002]

2. Description of the Related Art As a typical one of conventional rotation sensors, a sensor rotor and a sensor unit are provided so as to face each other, and when the sensor rotor rotates, a change in magnetic flux coupling occurs due to the influence of the uneven shape, and an output signal changes. An electromagnetic power generation system that detects a rotation speed is known.

An example of the electromagnetic sensor type rotation sensor is disclosed in Japanese Patent Laid-Open No. 26456/1993. In the rotation sensor of this publication, a bobbin around which a coil is wound concentrically with the sensor rotor is attached to a ferromagnetic transducer having a U-shaped cross section, and the sensor rotor is provided at two ends of the transducer facing the sensor rotor. Concavities and convexities that change the strength of magnetic flux coupling are alternately formed in the circumferential direction at a predetermined cycle.

[0004]

By the way, the conventional rotation sensor according to the above-mentioned publication is composed of a transducer having a U-shaped cross section, and this transducer is difficult to process and requires high cost.

Therefore, instead of such a difficult-to-machine transducer, a coil wound concentrically with the sensor rotor in an annular shape and an annular permanent magnet are provided between two flat plate-like or cylindrical ferromagnetic material rings. It is envisioned that a concavo-convex pattern which is sandwiched between the two ferromagnetic rings and is formed alternately on at least one of the two ferromagnetic rings at predetermined intervals in the circumferential direction to cause a change in the strength of magnetic flux coupling. In particular, it is considered preferable to form unevenness on both of the ferromagnetic rings.

However, in the rotation sensor of this type, if the phases of the concave and convex portions of the two ferromagnetic rings are deviated from each other, the sensor output is lowered. It is necessary to completely assemble with the use of, and at the time of assembly, it is necessary to temporarily fix the outer circumference with an adhesive or the like so as not to cause a phase shift until it is fixed by resin molding. Therefore, there is a problem that workability is deteriorated and extra man-hours are required.

In the present invention, attention is paid to various problems in improving the conventional rotation sensor having an annular shape, so that the phase shift of the concavities and convexities of the two ferromagnetic rings is set to a predetermined value or less in advance. By providing a positioning member and a member that engages with this in one ferromagnetic ring, and combining them together, it is possible to easily save unnecessary assembly man-hours without using any special assembly jig. An object is to provide a configuration of a rotation sensor that can improve work efficiency.

[0008]

As a means for solving the above-mentioned problems, the present invention includes a sensor rotor, a concentric magnet, and a bobbin around which a coil is wound, sandwiched between two ferromagnetic rings. Concavity and convexity are alternately formed on the ends of the ferromagnetic ring at a predetermined cycle, and at least one positioning member is provided on each surface of the bobbin that is in contact with the two ferromagnetic rings, and the positioning is performed on each of the two ferromagnetic rings. The shape of the member,
The rotation sensor is provided with an engaging member corresponding to the position.

In the rotation sensor having such a structure, it is preferable that the positioning member is a protrusion and the engaging member is a hole or a notch. Alternatively, the positioning member may be a recess or a groove, and the engaging member may be a protrusion adapted to the recess or the groove.

In any of the above rotation sensors, the relative positions of the positioning member and the engaging member are such that the phase deviations of the irregularities at the ends of the two ferromagnetic rings are within ± 13% of the angular pitch of the irregularities. It is preferable that the position is set.

[0011]

In the rotation sensor of the present invention having the above-mentioned structure, the magnet and the bobbin around which the coil is wound are sandwiched between the two ferromagnetic rings to be integrated with each other. It is desirable that the phases of the unevenness provided at the ends of the body ring are completely the same between both rings.

If there are no structural restrictions on the concavo-convex phase in order to match the phases with each other during assembly, for example, both rings are completely integrated until they are finally integrated with the resin material. It is necessary to temporarily fix the concave and convex phases so that they match each other. However, in the present invention, a positioning member is provided on the joining surface of the bobbin sandwiched between the two rings, and a positioning member is provided on each surface of the two ferromagnetic rings. Since the mating member is provided, when the two ferromagnetic rings are assembled, by simply aligning the engaging member of the ring with the positioning member of the bobbin, the concavities and convexities of both rings completely match, and it is easy to prevent the phase shift. can do.

The rotation speed detected by this rotation sensor is
Similar to the general one, the state of electromagnetic coupling with the sensor rotor used in combination changes due to the rotation of the sensor rotor, and this change is detected by the change in the output voltage of the sensor coil, and the rotation speed is detected. .

In the second and third aspects of the invention, as an embodiment, the positioning member and the engaging member are respectively provided with a projection and a hole or a notch, or a dent or a groove and a projection so that the phases can be reliably matched.

In the fourth aspect of the invention, the bobbin and the two ferromagnetic rings are provided so that the displacement of the relative positions of the positioning member and the engaging member is within 13% of the angular pitch. As a result, even if a slight phase of the unevenness occurs, the output voltage will not drop practically for accurate detection of the rotation speed.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a main sectional view of a bearing unit having a rotation sensor according to the first embodiment. This bearing unit 1
Is an inner ring 4 attached to the shaft end of a rotating shaft 3 inserted in the inner diameter of a cylindrical outer ring 2, and the rolling elements 6 and 7 are inserted between the rotating shaft 3, the inner ring 4 and the outer ring 2 to form the rotating shaft. 3 is rotatably supported. 5 is a nut, 8 is a retainer, and 9 is an inner diameter of the outer ring 2.

The rotation sensor 10 comprises a sensor rotor 11 attached to the shaft end 3a of the rotary shaft 3 and a sensor portion 12 used in combination therewith, and is fixed to a cap 13 attached to the outer ring 2 as shown in the figure. To be done.

FIG. 2 is an external perspective view of the rotation sensor 10 of the first embodiment. Although the sensor unit 12 is finally integrally surrounded by a resin material, it is omitted for simplicity of illustration.

In the sensor section 12, a coil 15 is wound concentrically with the sensor rotor 11 around an annular bobbin 14, an annular magnet 16 is provided adjacent to the bobbin 14, and these are provided with two annular ferromagnets. It is integrated by being surrounded by body rings 17a and 17b.

The bobbin 14, the coil 15 and the magnet 16 have substantially the same center radius, the coil 15 and the magnet 16 are juxtaposed in the axial direction of the rotating shaft, and two ferromagnetic material rings 17 are provided.
The a and 17b are provided with the magnet 16 and the bobbin 14 sandwiched so that 17a is on the inner diameter side and 17b is on the outer diameter side.

A large number of irregularities 18 are formed on the ends of the two ferromagnetic rings 17a and 17b on the side facing the sensor rotor 11.
Are alternately formed in a predetermined cycle. Further, at least one (two in the illustrated example) protrusions 1 are provided on the respective surfaces of the bobbin 14 that contact the two ferromagnetic rings 17a and 17b.
9a and 19b are provided.

Notches 2 are formed on the edges of the inner and outer ferromagnetic rings 17a and 17b opposite to the side surfaces of the projections and depressions 18 corresponding to the number, shape and position of the protrusions 19a and 19b.
0a and 20b are provided. The protrusions 19a, 19
The shape of b can be various shapes such as a cylinder and a prism.

The rotation sensor 10 of this embodiment having the above-described structure is used by assembling the sensor portion 12 and provided so as to face the sensor rotor 11.

When the sensor portion 12 is assembled, the inner and outer ferromagnetic rings 17a and 17b have a large number of irregularities 18, and it is necessary to make the phases of these irregularities completely match inside and outside. , In this example,
Without paying attention to the phase shift of the outer irregularities, just insert the protrusions 19a and 19b of the bobbin 14 into the notches 20a and 20b of the outer ferromagnetic rings 17a and 17b, and the phases of the irregularities are perfectly matched. Can be made.

As described above, the bobbin 14 around which the coil 15 is wound is inserted between the two ferromagnetic rings 17a and 17b, and then the magnet 16 is inserted, and the outer periphery of the magnet 16 is integrally fixed with a necessary resin material. .

Although not shown, terminals and cords connected to the coil 15 are provided at appropriate positions of the ferromagnetic material. When the sensor rotor 11 rotates, the state of magnetic flux coupling with the sensor rotor changes according to the rotation, and the rotational speed is detected by detecting the output fluctuation of the current generated in the coil.

FIG. 3 shows a main sectional view of the sensor portion of the rotation sensor of the second embodiment. This embodiment differs from the first embodiment only in that the bobbin 14 is provided with a groove and the ferromagnetic ring is provided with a projection instead of the projection provided in the bobbin 14 and the notch provided in the ferromagnetic ring. ing.

As shown in the drawing, the bobbin 14 is made to receive an inward projection provided on the ferromagnetic ring when the bobbin 14 is axially inserted and fitted between the two ferromagnetic rings. A groove is provided in the insertion direction.

The basic structure and operation are the same as those of the rotation sensor of the first embodiment.

FIG. 4 is an external perspective view of the rotation sensor of the third embodiment. In this embodiment, the sensor unit 12 has an annular bobbin 14 and a coil 15 which are concentrically provided with magnets 16 on the inner diameter side, and two ferromagnetic rings 17a provided on both sides of the rotary shaft in the axial direction. It is formed so as to be sandwiched by 17b. Note that the sensor rotor 1 is
1 is provided outside the sensor portion 12 in the radial direction so as to surround the sensor portion 12.

The two ferromagnetic rings 17a and 17b are provided with a large number of concavities and convexities 18 alternately formed on the outer periphery thereof at a predetermined cycle. Two ferromagnetic rings 17a, 1 of the bobbin 14
7b is provided at a suitable position on the surface in contact with 7b, and a projection 19 perpendicular to the surface is provided.
At least one a and 19b (two in the illustrated example) are provided. The holes 20a, 2 having the corresponding shapes and sizes are provided at the corresponding positions of the ferromagnetic rings 17a, 17b.
0b is provided.

In the rotation sensor of this embodiment constructed as described above, a detection signal is obtained in the sensor section 12 by the rotation of the sensor rotor 11 provided on the outer circumference.

When the sensor unit 12 is assembled, the coil 15
When the magnet 16 is wound around the bobbin 14, the magnet 16 is fitted to the inner diameter of the bobbin, and the projections 19a and 1a projecting to the side surface of the bobbin.
The holes 20 of the two ferromagnetic rings 17a and 17b are provided in 9b.
Align and fit a and 20b, and attach the ring to bobbin 14
To join. In this way, by simply aligning and fitting the holes of the ring with the protrusions of the bobbin 14, the protrusions and holes are provided in advance so that the positions of the irregularities 18 on the outer circumferences of the ferromagnetic rings 17a and 17b exactly match in advance. It is being done.

Also in this embodiment, it goes without saying that the necessary outer peripheral portion is then surrounded by a resin material to be integrated.

FIG. 5 shows a main sectional view of the rotation sensor of the fourth embodiment. In this embodiment, the projection and the insertion hole of the third embodiment are reversed, and the bobbin 14 is provided with a recessed portion and two inwardly projecting portions are provided inside the two ferromagnetic rings so that they are engaged with each other. The ferromagnetic rings 17a and 17b are fitted and integrated.

The other basic structure and operation are the same as those of the third embodiment, and the explanations thereof are omitted.

FIG. 6 shows the relationship between the phase shift of the uneven portion of the ferromagnetic ring of the rotation sensor and the output voltage. When there is a slight phase shift in the concavo-convex portions of the two ferromagnetic rings when the rotation sensor of any of the above embodiments is assembled, the output voltage changes depending on the magnitude of the phase shift. The result of measurement in FIG.

Number of teeth: 48 Angular pitch: 7.50 GAP: 0.45 mm Rotational speed: 20 rpm From the above measurement results, it is possible to find a phase shift of ± 1 ° or less, that is, a phase shift of 13% or less of the angular pitch of the irregularities. For example, it indicates that the output voltage decrease is less than 5%. This is well within the practical range. Therefore, in each of the above-mentioned embodiments, the ferromagnetic ring is provided so that the phase shift is ± 1 ° or less.
Sufficient assembly accuracy can be secured by attaching the engaging member and the positioning member to the bobbin.

[0039]

As described in detail above, according to the present invention, a positioning member and an engaging member are provided respectively for two ferromagnetic rings and a bobbin sandwiched between them so as to match the phases of the unevenness of the ring ends. Therefore, it is possible to eliminate wasteful work such as temporary fixing at the time of assembling work, and to exactly match the phase of the unevenness of both rings by simply engaging with the positioning member, while securing a large output voltage, The advantage is that the work efficiency can be improved.

As in the second and third inventions, the positioning member and the engaging member are respectively formed as a projection and a hole or a notch, or a depression or a groove and a projection, respectively, so that there is an advantage that the phase shift can be surely prevented. To be

In the fourth aspect of the invention, since the relative positions of the positioning member and the engaging member are set so that the phase shift is within ± 13% of the angular pitch of the concavities and convexities, both members are set with respect to the ferromagnetic ring and the bobbin. If it is manufactured in advance so as to ensure the above-mentioned accuracy, there is an advantage that the accuracy can be easily ensured by simply engaging and assembling both members with each other at the time of assembly.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a bearing unit including a rotation sensor according to a first embodiment.

FIG. 2 is an external perspective view and a partial cross-sectional view including a partial cross-section of the rotation sensor of the first embodiment.

FIG. 3 is a sectional view of a main portion of a rotation sensor according to a second embodiment.

FIG. 4 is an external perspective view and a partial cross-sectional view including a partial cross-section of a rotation sensor according to a third embodiment.

FIG. 5 is a sectional view of a main part of a rotation sensor according to a fourth embodiment.

FIG. 6 is a graph showing the relationship between the output voltage and the phase shift of the uneven portion of the ferromagnetic ring of the rotation sensor.

[Explanation of symbols]

 10 rotation sensor 11 sensor rotor 12 sensor part 13 cap 14 bobbin 15 coil 16 magnets 17a, 17b ferromagnetic material ring 18 unevenness 19a, 19b protrusions 20a, 20b hole

Claims (4)

[Claims] 1. A bobbin wound with a magnet and a coil which are concentric with the sensor rotor is sandwiched between two ferromagnetic rings, and irregularities are alternately formed at predetermined intervals at the ends of the two ferromagnetic rings. A rotation sensor in which at least one positioning member is provided on each surface of the bobbin that is in contact with the two ferromagnetic rings, and an engaging member corresponding to the shape and position of the positioning member is provided on each of the two ferromagnetic rings. . 2. The rotation sensor according to claim 1, wherein the positioning member is a protrusion and the engaging member is a hole or a notch. 3. The rotation sensor according to claim 1, wherein the positioning member is a recess or a groove, and the engaging member is a protrusion adapted to the recess or the groove. 4. The relative positions of the positioning member and the engaging member are set so that the phase deviations of the irregularities at the ends of the two ferromagnetic rings are within ± 13% of the angular pitch of the irregularities. The rotation sensor according to claim 1, wherein the rotation sensor is a rotation sensor.