JP2981679B2 - Electromagnetic induction type rotation detector - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic induction type rotation detector, and more particularly, to a magnetic body in which a coil is wound, and a rotating surface of the rotary body has an axial tip of the magnetic body. The present invention relates to an electromagnetic induction type rotation detector arranged so that surfaces are opposed to each other.

[Conventional technology]

As an electromagnetic induction type rotation detector, for example,
As disclosed in Japanese Patent No. 105847, a rotation detector in which a coil is wound around a magnetic body is known. In this publication, it is proposed that the shape of the magnetic material is formed in a truncated cone shape in order to optimize the magnetic flux density over the entire length of the magnetic material in view of the relationship between the magnetic material and the rotating body facing the magnetic material. . That is, it has a frustoconical magnetic body and a cylindrical bobbin that houses the magnetic body, and the coil winding is wound around the bobbin.

[Problems to be solved by the invention]

In the above prior art, the shape of the magnetic body is improved in view of the relationship between the rotating body and the magnetic body, but the specific structure of the coil and the like is not clarified. If the magnetic body is formed in a truncated cone shape in accordance with the above-mentioned conventional technology, it is desirable that the shaft of the bobbin accommodating the magnetic body has a shape following the shape of the magnetic body and has a tapered surface. When the outer surface of the bobbin shaft is a cylindrical surface, the shaft is formed based on the large-diameter end of the magnetic body, and the thickness of the shaft around the small-diameter end is increased. The number of windings will be reduced. Therefore, it is necessary to use a bobbin provided with a shaft portion having a tapered surface and wind a coil winding on the bobbin. However, the winding operation is difficult because the winding slides on the tapered surface at the start of winding. Therefore, the workability is significantly reduced as compared with the conventional case.

Therefore, the present invention relates to an electromagnetic induction type rotation detector in which a coil is wound around a magnetic body having a tapered portion, and a bobbin housing the magnetic body has a tapered shape, and a coil winding is wound on the bobbin shaft. It is intended to be able to be easily wound around the part.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a magnetic material having a tapered portion whose cross-sectional area gradually increases in the axial direction from a distal end to a proximal end, and a coil of the magnetic material is mounted on a rotating surface of a rotating body. In the electromagnetic induction type rotation detector arranged such that the direction end faces face each other, the winding constituting the coil is wound around a shaft having a tapered surface corresponding to the tapered portion of the magnetic material, and at least the A cylindrical bobbin that accommodates a part of the magnetic material in the hollow portion, and a connector that has a built-in terminal that is connected to the bobbin and that is electrically connected to the winding of the coil. A groove is formed from the small-diameter end to the large-diameter end of the shaft portion, and a locking projection is formed on the bobbin on an extension of the groove, and the winding is positioned at a predetermined position via the groove and the locking projection. It is intended to be guided to.

The magnetic body includes a core having a distal end portion opposed to a rotating body, and a permanent magnet joined to a base end portion of the core. And a tapered portion having a gradually increasing cross-sectional area.

[Action]

In the electromagnetic induction type rotation detector configured as described above, a tapered surface is formed on the shaft portion of the bobbin corresponding to the magnetic body having the tapered portion, but the shaft portion has a small diameter end to a large diameter end. Are formed. For this reason, when winding the coil around the bobbin, the winding is guided into the groove at the beginning of winding, so that the winding can be easily wound around the bobbin shaft without slippage. In addition, since the locking projection is formed on the bobbin on the extension of the groove, the winding extending from the groove is guided to a predetermined position via the locking projection.

Thus, for example, when the above-mentioned magnetic body is formed of a permanent magnet, a magnetic circuit is formed in which the magnetic flux from one magnetic pole of the permanent magnet returns to the other magnetic pole of the permanent magnet via a coil. When the rotating body disposed opposite to the magnetic body rotates, an air gap formed between the rotating body and the magnetic body changes due to the presence of teeth formed on the outer periphery of the rotating body, for example.
As a result, the flux linkage to the coil changes in accordance with the rotation of the rotator, and an electromotive force is induced in the coil by the electromagnetic induction to output a pulse signal.

〔Example〕

Hereinafter, preferred embodiments of the electromagnetic induction type rotation detector of the present invention will be described with reference to the drawings.

1 to 6 show an embodiment of the electromagnetic induction type rotation detector according to the present invention, which is provided for a crank angle detection device for an internal combustion engine. That is, as shown by a two-dot chain line in FIG. 1, an electromagnetic induction type rotation detector is formed so that a tooth portion 21 is formed on a rotating surface and faces a rotating body 20 of a magnetic material which rotates in synchronization with an internal combustion engine (not shown). A barrel electromagnetic pickup 1 is arranged.

The electromagnetic pickup 1 contains a core 2, a substantially columnar permanent magnet 3 joined to a base end thereof, a core 4 and a permanent magnet 3, and a coil 4 wound around a shaft containing the core 2. The bobbin 5 is turned. The core 2 includes a tapered portion 2b formed of a magnetic material into a substantially truncated cone shape, and a columnar tip portion 2a formed continuously with a small diameter end thereof. The core 2 may be formed of a laminate of a plurality of silicon steel plates.

The bobbin 5 is a synthetic resin cylindrical body including a small-diameter cylindrical body portion 5a, a tapered portion 5b having a tapered surface, and a large-diameter cylindrical body portion 5c. Hollow portions having a large diameter circular cross section are formed continuously, and the core 2 and the permanent magnet 3 are accommodated in these hollow portions, respectively. As shown in FIG. 2, a pair of engaging projections 5f and 5g are formed on the outer surface of the large-diameter cylindrical body 5c of the bobbin 5, as shown in FIG. Also,
The flanges 5d and 5 are provided at the distal end of the cylindrical body 5a and the large diameter
e are integrally formed, and the winding of the coil 4 is wound between these flange portions 5d and 5e as described later.

The connector 6 has a pair of terminals (only one of which is indicated by 7 in the figure) formed by insert resin molding, and FIGS.
It is formed in the shape shown in the figure. That is, it has a bottomed cylindrical body portion 6a and a joining portion 6b, each axis is formed so as to be substantially orthogonal, and one end of the terminal 7 extends from the cylindrical body portion 6a as an extension portion 7a. And the other end joins as connection terminal 7b
6b. A step 6c that forms an annular step together with one side wall of the joint 6b is formed integrally on the outer periphery near the bottom of the cylindrical body 6a. Further, a pair of rectangular extending portions 6d and 6e extending in the axial direction from the opening end of the cylindrical portion 6a are integrally formed, and a rectangular engaging hole as shown in FIG. 6f and 6g are drilled. These engagement holes 6f, 6g
The engagement projections 5f, 5g of the bobbin 5 are engaged with the bobbin 5, and the bobbin 5 and the connector 6 are joined, so that a so-called snap-fit structure is provided. Further, an annular groove 6h is formed on the outer periphery of the cylindrical body 6a, and the O-ring 10 is fitted in the annular groove 6h. Thus, the core 2 and the permanent magnet 3 are accommodated in the hollow portion of the cylindrical portion 6a and the bobbin 5, and a spring washer 11 is interposed between the end surface of the permanent magnet 3 and the bottom surface of the cylindrical portion 6a. The core 2 and the permanent magnet 3 are pressed in the direction of the tapered portion 5b.

As shown in FIGS. 1 and 3, the cylindrical body portion 5c of the bobbin 5 is provided.
, A pair of terminals (only one is indicated by 17 in the figure) is fixed, and the end of the winding of the coil 4 is wound around each connecting portion 17a and soldered. A pair of terminals 17
After the bobbin 5 and the cylindrical body 6a are joined as described above, each of them overlaps with the extension 7a of the terminal 7 and is joined by projection welding. After being joined in this way,
As shown in FIG. 2, an insulating tape 15 (not shown in FIGS. 1 and 3) is wound, and similarly, the insulating tape 14 is wound around the coil 4.

FIG. 4 shows a side view of a part of the electromagnetic pickup 1, in which the case 8, the coil 4 and the insulating tape 14 are removed from the electromagnetic pickup 1 of FIG. Is shown standing.
As is apparent from FIG. 5, the tapered portion 5b of the bobbin 5 is formed with a concave groove 5h extending from the small diameter end to the large diameter end. The flange 5e provided at the large-diameter end of the tapered portion 5b is notched near the tip of the groove 5h. Further, a locking projection 5i is provided on the outer surface of the cylindrical body 5c on the extension of the groove 5h. The terminal 17 is fixed to the cylindrical body portion 5c as described above, and a tongue-shaped connecting portion 17a is erected (see a two-dot chain line in FIG. 5).

When the winding of the coil 4 is wound around the bobbin 5, first, as shown by the two-dot chain line in FIG. 5, the winding is wound counterclockwise around the tip of the connecting portion 17a. After being wound counterclockwise again at the base end of the
The winding is guided to the cylindrical body 5a via the groove 5h (from the left side of the locking projection 5i in FIG. 4) via the 5i. And the flanges 5d, 5e
It is sequentially wound on the cylindrical portion 5a and the tapered portion 5b therebetween. When the winding is wound, the winding is led out through a notch (not shown) of the flange 5e on the back side in FIG. 4, and a terminal on the back side similar to the terminal 17 (right side in FIG. 5). Terminal). The winding wound in this manner is soldered only to the winding portion at the end of the connecting portion 17a of the terminal 17, and then the connecting portion 17a is bent and the bobbin 5 is bent as shown by an arrow in FIG. Be parallel to the axis. At this time, coil 4
Since the winding passes through the locking projection 5i, it is not located below the connecting portion 17a as shown in FIG. 6, and therefore, there is no possibility that the winding is crushed by the connecting portion 17a.

A case 8 shown in FIGS. 1 to 3 is provided so as to surround the bobbin 5 and the cylindrical body 6a assembled as described above, and the end surface of the tip 2a of the core 2 is in contact with the bottom surface thereof. . The case 8 is a bottomed cylindrical body made of metal, for example, stainless steel, and is press-fitted into the outer surface between the annular groove 6h of the cylindrical body 6a and the step 6c. The open end 8a of the case 8 has a shape that is expanded outward, and a flat portion at the tip comes into contact with the step 6c,
It is in close contact with this. Then, a flange 9 is formed by integral molding of synthetic resin so as to surround the step 6c and the opening end 8a of the case 8. A pair of metal collars 12 are insert-molded on the flange 9 as shown in FIG.

The operation of the electromagnetic pickup 1 configured as described above will be described. In FIG. 1, a predetermined magnetic flux distribution is formed in the core 2 by the permanent magnet 3, and the cross-sectional area of the tip 2 a is the same as that of the permanent magnet 3. Since it is smaller, the leakage magnetic flux from the tip 2a is suppressed, and the optimum magnetic flux density is obtained.
When the rotating body 20 rotates, the magnetic flux distribution changes each time the tooth portion 21 faces the tip end surface of the core 2. As a result, the amount of magnetic flux linked to the coil 4 changes, and
Since the output is opposite when approaching the tooth portion 21 and when separating from the tooth portion 21, the coil 4 is attached to the coil 4 by electromagnetic induction.
An AC voltage is induced in accordance with the rotation of the motor, and is output as a signal indicating the rotation speed.

〔The invention's effect〕

Since the present invention is configured as described above, the following effects can be obtained.

That is, in the electromagnetic induction type rotation detector of the present invention, the magnetic body having a tapered portion is provided, and the bobbin has a tapered surface corresponding to the magnetic body. Is formed, and a locking projection is formed on the bobbin on the extension of this groove, and the coil winding is guided to a predetermined position through the groove and the locking projection.
The winding operation at the start of winding is easy, and good workability is obtained.

[Brief description of the drawings]

1 is a longitudinal sectional view of an electromagnetic pickup according to one embodiment of the present invention, FIG. 2 is a longitudinal sectional view of the electromagnetic pickup shown in FIG. 1 as viewed from the side, and FIG. FIG. 4 is a partial cross-sectional view showing a connection portion between a terminal and a coil, and FIG.
The figure is a front view of a state in which a coil is wound around the bobbin in FIG. 4,
FIG. 6 is a side view showing a state in which a coil is wound around the bobbin of FIG. 1 ... Electromagnetic pickup (Electromagnetic induction rotation detector) 2 ... Core (magnetic material), 3 ... Permanent magnet (magnetic material), 4 ... Coil, 5 ... Bobbin, 5a ... Cylinder, 5b ... taper, 5c ... cylinder, 5f, 5g ... engagement projection, 5h ... groove, 5i ... locking projection, 6 ... connector, 6a ... cylinder, 6b ... joint , 6c ... step, 6d, 6e ... extension, 6f, 6g ... engagement hole, 7 ... terminal, 8 ... case, 9 ... flange, 10 ... O-ring, 11 ... spring Washer, 17 …… Terminal, 20 …… Rotating body

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01P 1/00-3/80 G01D 5/00-5/246 H01F 41/06-41/12 H01F 27/32 G01R 33 / 02

Claims (1)

(57) [Claims] 1. A coil is wound around a magnetic body having a tapered portion whose cross-sectional area gradually increases in the axial direction from a distal end to a base end, and an axial distal end face of the magnetic body faces a rotating surface of a rotating body. In the electromagnetic induction type rotation detector arranged as described above, a winding constituting the coil is wound around a shaft portion having a tapered surface corresponding to the tapered portion of the magnetic body, and at least a part of the magnetic body is wound. A bobbin of a cylindrical body housed in the hollow portion, and a connector having a terminal that is connected to the bobbin and that is electrically connected to the winding of the coil. A groove reaching the large diameter end is formed, and a locking projection is formed on the bobbin on an extension of the groove, and the winding is guided to a predetermined position through the groove and the locking projection. An electromagnetic induction type rotation detector characterized by the above-mentioned.