JP2981681B2 - 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]

For example, Japanese Patent Application Laid-Open No.
As disclosed in Japanese Patent No. 321368, a rotation detector in which a coil is wound around a magnetic body is known. In this publication, it is proposed to provide a thin insulating member between a tip surface of a core member and a cap (case), and a structure is disclosed in which the cap is coupled to a sensor body by caulking an opening end. Have been. An O-ring is interposed between the cap and the sensor body to seal between the two.

[Problems to be solved by the invention]

However, in the detector described in the above publication, the caulked portion of the cap to the sensor body is exposed to the outside. For this reason, it is necessary to take measures such as adding one more O-ring in order to secure a sufficient sealing property and obtain a waterproof structure.
In addition, since the diameter of the caulked portion of the sensor body is small, the strength of this portion is weakened.

Accordingly, it is an object of the present invention to secure sufficient sealing performance while maintaining the strength of the entire rotation detector with a simple structure in an electromagnetic induction rotation detector.

[Means for solving the problem]

In order to achieve the above object, the present invention provides an electromagnetic induction type rotation detector in which a coil is wound around a magnetic body, and the magnetic body is disposed so that an axial end face of the magnetic body faces a rotating surface of a rotating body. A cylindrical bobbin for winding the coil and accommodating the magnetic body in the hollow portion, a connector having a terminal for electrically connecting to the coil, and a crimping opening end portion for accommodating the bobbin and the connector; There is provided a bottomed cylindrical case to be joined, and a flange integrally formed of synthetic resin so as to surround a caulked joint between the case and the connector.

The rotating body may be, for example, a circular magnetic body provided with teeth on the rotating surface, but may be a rotating magnetic surface having different magnetic poles formed alternately.

[Action]

In the electromagnetic induction type rotation detector configured as described above, the flange is integrally formed of synthetic resin so as to surround the caulked joint between the case and the connector, so that a stable sealing property is ensured and A predetermined strength is ensured for the case. 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 and 2 show an embodiment of an 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 accommodates a core 2, a columnar permanent magnet 3 joined to a base end thereof, a core 2 and the permanent magnet 3, and winds a coil 4 around a shaft portion accommodating the core 2. The bobbin 5 is provided. The core 2 is made of a magnetic material and has a small-diameter cylindrical tip 2a and a large-diameter disc-shaped base 2b. The core 2 may be formed of a laminate of a plurality of silicon steel plates.

The bobbin 5 has a small-diameter cylindrical portion 5a, a step portion 5b and a large-diameter cylindrical portion 5a.
A stepped cylindrical body made of synthetic resin made of c, a hollow portion having a small diameter circular cross section and a hollow portion 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. I have. Flanges 5d and 5e are formed integrally with the distal end of the cylindrical body 5a and the step 5b, respectively, and the winding of the coil 4 is wound between the flanges 5d and 5e. Large diameter cylindrical body 5c of bobbin 5
As shown in FIG. 2, a pair of engaging projections 5f and 5g are formed in the outer surface of the pair in the axial direction.

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 portion near the bottom of the cylindrical portion 6a has a small diameter and a step 6c is formed. Further, as shown in FIG. 2, a pair of extension portions extending in the axial direction from the open end of the cylindrical body portion 6a.
6d and 6e are integrally formed, and each has an engagement hole 6
f, 6g are drilled. The engagement holes 6f and 6g engage with the engagement protrusions 5f and 5g of the bobbin 5, and the bobbin 5 and the connector 6
Are joined to form a so-called snap-fit structure. Further, an annular groove is formed on the outer periphery of the cylindrical body 6a.
6h is formed, and the O-ring 10 is fitted to this. Thus, the core 2 and the permanent magnet 3 are accommodated in the hollow portion of the cylindrical body 6a and the bobbin 5, and a spring washer 11 is interposed between the end face of the permanent magnet 3 and the bottom of the cylindrical body 6a. The core 2 and the permanent magnet 3 are pressed in the direction of the step 5b.

As shown in FIG. 1, a pair of terminals 17 (only one is shown in the figure) is fixed to the cylindrical body 5c of the bobbin 5, and the ends of the windings of the coil 4 are wound around the respective free ends. After being soldered and joined, it is bent in the direction of the cylindrical body 5c. The other end of each of the pair of terminals 17 is connected to the extension 7a of the terminal 7 by projection welding after the bobbin 5 and the cylindrical portion 6a are joined as described above. After such connection, an insulating tape (not shown) is wound.

A case 8 is provided so as to surround the bobbin 5 and the cylindrical body 6a formed as described above, and the end face of the tip 2a of the core 2 is in contact with the bottom surface. The case 8 is a bottomed cylindrical body made of metal, for example, stainless steel, and its open end 8a is caulked and locked to the step 6c. 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.

In the electromagnetic pickup 1 having the above-described configuration, the flange 9 surrounds the joint between the step 6c and the opening end 8a.
Are integrally formed, so that a stable sealing property can be secured. At this time, since the caulking position of the case 8 is located above the lower surface of FIG.
Even when an external force is applied to the case 8, it can sufficiently resist this.

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. When the rotating body 20 rotates, the magnetic flux distribution changes each time the teeth 21 face the tip end surface of the core 2. As a result, the amount of magnetic flux interlinking with the coil 4 changes, and the output is reversed when approaching and separating from the tooth portion 21 of the rotating body 20. An AC voltage corresponding to the 20 rotations is induced and output as a signal indicating the number of rotations.

FIG. 3 shows another embodiment of the present invention, in which a core 2 comprises a tapered portion 2c formed in a substantially truncated cone shape, and a cylindrical tip portion 2d formed continuously at a small diameter end thereof. An annular convex portion 6i is formed on the connector 6, and an O-ring 10 is fitted in an annular groove 6j formed substantially at the center. The open end of the case 8 is swaged and joined so as to surround the projection 6i, and a flange 9 is integrally formed therearound with a synthetic resin. Other configurations are shown in FIG. 1 and FIG.
Since it is substantially the same as the embodiment of the figure, the same reference numerals are given and the description is omitted. Thus, in this embodiment, the optimum magnetic flux density is obtained over the entire length from the permanent magnet 3 to the tip 2d,
The case 8 and the connector 6 have a strong joint structure.

FIG. 4 shows still another embodiment of the present invention.
Open end of case 8 for the embodiment shown in FIGS.
8a is covered with a heat-shrinkable tube 13. That is, after the open end 8a of the case 8 is swaged to the step 6c of the connector 6, the heat-shrinkable tube 13 is coated so as to surround the joint of the open end 8a with the step 6c. The flange 9 is formed by integral molding of the resin. Due to the heat at this time,
Alternatively, since heat is applied in advance, the heat-shrinkable tube 13 contracts and comes into close contact with the joint between the open end 8a and the step 6c, so that the resin does not flow into the case 8 when the flange 9 is formed. Further sealing performance can be ensured as compared with the embodiment. The remaining configuration is the same as that of the embodiment shown in FIGS.

〔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, since the caulked joint between the case and the connector is covered by the flange integrally formed of the synthetic resin, a stable sealing property can be secured. Moreover, since the caulked joint between the connector and the case does not exist outside the mounting surface of the flange, sufficient strength is secured.

[Brief description of the drawings]

FIG. 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 viewed from the side, and FIG. FIG. 4 is a longitudinal sectional view of an electromagnetic pickup according to an embodiment, and FIG. 4 is a longitudinal sectional view of an electromagnetic pickup according to still another embodiment of the present invention. 1 ... Electromagnetic pickup (Electromagnetic induction rotation detector) 2 ... Core (magnetic material), 3 ... Permanent magnet (magnetic material), 4 ... Coil, 5 ... Bobbin, 5a ... Cylinder, 5b ... Step, 5c ... Tube, 5f, 5g ... Engagement protrusion, 6 ... Connector, 6a ... Tube, 6b ... Joint, 6c ... Step, 6d, 6e ... Extension part, 6f, 6g ... engagement hole, 7 ... terminal, 8 ... case, 9 ... flange, 10 ... O-ring, 11 ... spring washer, 13 ... heat-shrinkable tube, 17 ... Terminal, 20 ... Rotating body

Claims (1)

(57) [Claims] 1. An electromagnetic induction type rotation detector in which a coil is wound around a magnetic body and an axial end face of the magnetic body is arranged to face a rotating surface of a rotating body. A cylindrical bobbin accommodating the magnetic body in a hollow portion, a connector having a terminal for electrically connecting to the coil, and a bottomed cylindrical body accommodating the bobbin and crimping an open end to the connector. And a flange integrally formed of a synthetic resin so as to surround a caulked joint between the case and the connector.