JPH04188075A - Electromagnetic induction type rotation detector - Google Patents

Abstract

PURPOSE:To support a magnetic body and a coil wound thereon in a stable state by a construction wherein a bobbin having the coil wound thereon and holding the magnetic body therein is held in a case of a bottomed tubular body and joined to a connector. CONSTITUTION:A pair of extension parts 6d and 6e extending in the axial direction from the open end of a tubular body part 6a are formed integrally and engagement holes 6f and 6g are made those parts. A construction is so made that engagement projections 5f and 5g of a bobbin 5 engage with these engagement holes 6f and 6g so that the bobbin 5 and a connector 6 are joined together, and thereby a so-called snap fit structure is formed. The bobbin 5 is supported in a case 8 in close contact therewith by projections of flange parts 5d and 5e and it is supported reliably without play due to vibration, a thermal strain, etc. Thereby a stable output characteristic can be ensured.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an electromagnetic induction type rotation detector, and in particular, the present invention relates to an electromagnetic induction type rotation detector, in particular, which is made by winding a coil around a magnetic material, and has an axial tip of the magnetic material on the rotating surface of the rotating body. This relates to an electromagnetic induction rotation detector arranged so that the surfaces thereof face each other.

[Conventional technology]

As an electromagnetic induction type rotation detector, for example, JP-A-1-3
As disclosed in Japanese Patent No. 21368, a rotation detector in which a coil is wound around a core member is known. The publication proposes providing a thin insulating member between the tip surface of the core member and the cap (case), and discloses a structure in which the cap is connected to the sensor body by caulking the open end. has been done. Also, Utsukai Showa 61-1
Japanese Patent No. 65077 proposes an ignition signal coil in which the entire iron core, permanent magnet, coil, etc. are molded from synthetic resin. Furthermore, in Japanese Utility Model Application Publication No. 61-182850, the winding of the coil is made to approximate the external shape set in advance, and the coil is wound by injection molding of a resin material so as to surround the ball (core), magnet, bobbin, and coil. A rotation detection device having a device housing has been proposed.

[Problem to be solved by the invention]

When the rotation detection device is made of resin material, the linear expansion coefficients of the Koinope terminal and the synthetic resin surrounding it are different, so thermal strain is repeatedly applied in response to changes in ambient temperature, causing the coil, terminal, etc. When tensile stress occurs in
There is a risk of the coil winding breaking.

On the other hand, if a cap (case) is attached as described in the above-mentioned Japanese Patent Application Laid-Open No. 1-321368, synthetic resin will not be filled in the joint between the coil and the terminal and the coil winding. I can do something. However, if there is a gap between the bobbin that winds the coil and houses the magnetic material, and the cap that houses it, the bobbin will become loose when thermal strain, vibration, etc. are applied to the rotation detector, and the magnetic material will become loose. There is a risk that the output characteristics may fluctuate because the body is not fixed at a fixed position.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an electromagnetic induction rotation detector that can stably support a magnetic material and a coil wound around the magnetic material.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention involves winding a coil around a magnetic body, and arranging the coil so that the axial end surface of the magnetic body faces the rotating surface of a rotating body. The electromagnetic induction rotation detector includes: a cylindrical bobbin around which the coil is wound and the magnetic material housed in a hollow part; a connector housing a terminal electrically connected to the coil; and a connector housing the bobbin. and a bottomed cylindrical case whose open end is joined to the connector, and at least one protrusion is formed on the outer periphery of the bobbin.

[Effect]

In the electromagnetic induction rotation detector configured as described above, after a coil is wound around the bobbin and a magnetic material is housed therein, the bobbin is housed in a bottomed cylindrical case and connected to a connector. Ru. At this time, since at least one protrusion is formed on the outer periphery of the bobbin, this protrusion comes into close contact with the inner surface of the case, and even if there is a gap between the bobbin and the inner surface of the case, rattling is prevented.

For example, if the magnetic body is made of a permanent magnet,
A magnetic circuit is formed in which the magnetic flux from one pole of the permanent magnet returns to the other pole of the permanent magnet via the coil. Then, when the rotating body disposed opposite to the magnetic body rotates, the 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 rotating body, and an electromotive force is induced in the coil by electromagnetic induction, and a pulse signal is output.

〔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 the electromagnetic induction rotation detector of the present invention, which is used in a crank angle detection device for an internal combustion engine. That is, as shown by the two-dot chain line in FIG. 1, the electromagnetic induction rotation detector is arranged so as to face a rotating body 20 made of magnetic material that has teeth 21 formed on its rotating surface and rotates in synchronization with an internal combustion engine (not shown). A barrel electromagnetic pickup l is arranged.

The electromagnetic pickup l includes a core 2, a substantially cylindrical permanent magnet 3 joined to the base end thereof, and a coil 4 wound around the shaft portion housing the core 2 and the permanent magnet 3. It is equipped with a spun bobbin 5. The core 2 consists of a tapered part 2b formed of a magnetic material into a substantially truncated conical shape, and a cylindrical tip part 2a formed continuously at the small diameter end of the tapered part 2b.

Note that this core 2 may be formed of a laminate of a plurality of silicon steel plates.

The bobbin 5 is a synthetic resin cylinder consisting of a small diameter cylinder part 5a, a tapered part 5b with a tapered surface, and a large diameter cylinder part 5C. Hollow portions with a large diameter and approximately circular cross section are continuously formed, and the core 2 and the permanent magnet 3 are accommodated in these hollow portions, respectively. Flange parts 5d and 5e are integrally formed at the tip of the cylindrical body part 5a and the large diameter end of the tapered part 5b, respectively, and the winding of the coil 4 is wound between these collar parts 5d and 5e. has been done.

As shown in FIGS. 3 and 4, a plurality of protrusions 5p and 5q are formed on the outer periphery of the collar portions 5d and 5e, respectively. In this embodiment, three protrusions are formed at equal intervals. On the outer surface of the large-diameter cylindrical portion 5c of the bobbin 5, a pair of locking protrusions 5f and 5g are formed in the axial direction, as shown in FIG.

The connector 6 has a pair of terminals (only one terminal is connected to 7 in the figure).
) is molded with insert resin to have the shape shown in FIGS. 1 and 2. That is, it has a cylindrical body part 6a in the shape of a cylinder with a bottom and a joint part 6b, and is formed so that the axes thereof are substantially perpendicular to each other, and one end of the terminal 7 is connected to the extending part 7a.
The other end extends from the cylindrical body portion 6a as a connecting terminal 7b into the recessed portion of the joint portion 6b. A step portion 6c, which forms an annular step portion together with one side wall of the joint portion 6b, is integrally formed on the outer periphery of the cylindrical body portion 6a near the bottom. Also, the second
As shown in the figure, a pair of extending portions 6d and 6e extending in the axial direction from the open end of the cylindrical body portion 6a are integrally formed.
Retaining holes 6f and 6g are bored in these. Engaging protrusions 5f and 5g of the bobbin 5 are inserted into these retaining holes 6f and 6g.
The bobbin 5 and the connector 6 are engaged with each other to connect the bobbin 5 and the connector 6, which is a so-called snap fit structure.

Further, an annular groove 6h is formed on the outer periphery of the cylindrical body portion 6a, into which an O-ring 10 is fitted. Thus, the core 2 and the permanent magnet 3 are housed in the hollow part of the cylindrical body part 6a and the hobbin 5, or the spring washer 11 is interposed between the end face of the permanent magnet 3 and the bottom face of the cylindrical body part 6a. The core 2 and the permanent magnet 3 are pressed in the direction of the tapered portion 5b.

As shown in FIG. 1, a pair of terminals (only one is shown as 17 in the figure) are fixed to the cylindrical portion 5C of the bobbin 5, and the winding of the coil 4 is wound around one end of each terminal and soldered. It is joined. The other end of each of the pair of terminals 17 is
After the bobbin 5 and the cylindrical body part 6a are joined as described above, they overlap with the extension part 7a of the terminal 7 and are joined by projection welding. After joining in this manner, an insulating tape 15 (not shown in FIG. 1) is wound as shown in FIG. 2, and an insulating tape 14 is similarly wound around the outer periphery of the coil 4.

A case 8 is provided so as to surround the bobbin 5 and the cylindrical body part 6a assembled as described above, and the core 2 is attached to the bottom surface of the case 8.
The end surfaces of the tip portions 2a are in contact with each other. This case 8 is a bottomed cylindrical body made of metal, for example, stainless steel, and is press-fitted into the outer surface of the cylindrical body portion 6a between the annular groove 6h and the step portion 6C. At this time, a plurality of protrusions 5 formed on the outer periphery of the flanges 5d and 5e
p and 5q are in close contact with the inner surface of the case 8, and the bobbin 5 is supported within the case 8 so as not to vibrate. Note that one protrusion p, q may be formed, and in this case, the protrusions p, q and the outer circumferential surfaces of the flanges 5d, 5e will come into close contact with the inner surface of the case 8. In addition, the opening end 8 of the case 8
The tip a has a shape that expands outward, and the flat portion at the tip abuts on the stepped portion 6c and is in close contact with the stepped portion 6c. Then, a flange 9 is formed by integral molding of synthetic resin so as to surround the stepped portion 6C and the open end 8a of the case 8. A pair of metal collars 12 are insert-molded into the flange 9 as shown in FIG.

To explain the operation of the electromagnetic pickup 1 configured as above, 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 2a is The tip part 2a is smaller than the
The magnetic flux leakage from the magnet is suppressed, resulting in the optimum magnetic flux density. When the rotating body 20 rotates, the magnetic flux distribution changes each time the toothed portion 21 faces the distal end surface of the core 2. As a result, the amount of magnetic flux interlinking with the coil 4 changes, and the output is in the opposite direction when approaching the teeth 21 of the rotating body 20 and when moving away from the toothed part 21 of the rotating body 20. An alternating current voltage corresponding to the rotation of the motor 20 is induced and output as a signal indicating the number of rotations. In particular, as mentioned above, the bobbin 5 is attached to the case 8 by the protrusions 5p and 5q of the flanges 5d and 5e.
It is tightly supported within the body, and is reliably supported without any play caused by vibration, thermal strain, etc. Therefore, even if vibration, thermal strain, etc. are applied to the electromagnetic pickup l, no play occurs in the bobbin 5, and a stable output signal is ensured.

〔Effect of the invention〕

Since the present invention is configured as described above, it produces the effects described below.

That is, the electromagnetic induction rotation detector of the present invention is configured to be housed in a bobbin around which a coil is wound and accommodates a magnetic material, or in a bottomed cylindrical case and connected to a connector. At least one protrusion is formed on the bobbin, and since this protrusion comes into close contact with the inner surface of the case, the bobbin can be stably supported within the case. Therefore, even if thermal strain, vibration, etc. are applied, no rattling will occur in the bobbin and thus in the magnetic material, and stable output characteristics can be ensured.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an electromagnetic pickup according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of the electromagnetic pickup shown in FIG. I-
FIG. 4 is a sectional view taken along the line IV-IV. l... Electromagnetic pickup (electromagnetic induction rotation detector) 2
... Core (magnetic material), 3... Permanent magnet (magnetic material). 4... Coil, 5... Bobbin, 5a...
・Cylinder part. 5b... Taper part, 5c... Cylindrical body part. 5f, 5g...engaging protrusion, 5'p, 5q...
protrusion. 6... Connector, 6a... Cylindrical body part. 6b...Joint part, 6c...Step part. 6d, 6e...extending portion, 6f, 6g...engaging hole. 7...Terminal, 8...Case. 9...Flange, lO...0 ring. 11... Spring washer.

Claims (1)

[Claims] (1) In an electromagnetic induction rotation detector in which a coil is wound around a magnetic body and arranged so that the axial end surface of the magnetic body faces the rotating surface of the rotating body, the coil is wound and the magnetic body is a cylindrical bobbin that accommodates a body in a hollow portion; a connector that includes a built-in terminal that electrically connects to the coil; and a bottomed cylindrical case that accommodates the bobbin and has an open end joined to the connector. An electromagnetic induction rotation detector comprising: at least one protrusion formed on the outer periphery of the bobbin.