JPH09196181A - Resin sealing structure - Google Patents

Abstract

(57) Abstract: [PROBLEMS] To enhance the sealing reliability when a resin is directly molded around a metal member to seal and protect internal components. SOLUTION: An annular groove 9 is provided on the outer circumference of a magnetic pole piece 1, a thermoplastic resin sealant 10 is applied thereto, and then a resin housing 7 is provided outside the sealant 10 by molding. In this case, the groove 9 serves as a sealant reservoir, and the sealant 10 surely stops at the sealing interface of the housing, and the sealant 10 absorbs the thermal expansion / contraction difference between the housing 7 and the pole piece 1. Therefore, no gap is formed at the sealing interface, and the reliability of hermetic sealing is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic pole detector for detecting the number of revolutions, for example, a resin sealing structure used for an electromagnetic pickup.

[0002]

2. Description of the Related Art An electromagnetic pickup of a rotation sensor used for detecting the number of rotations of a wheel or the like has a coil for generating a signal voltage on the outer circumference of a magnetic pole element that causes a magnetic flux from a magnet to flow toward a sensing rotor.

This coil dislikes water and therefore needs to be covered and protected by a housing. As a structure for protecting it at a low cost, a resin for the housing material is molded on the outside of the coil assembly, and this resin is closely adhered to the outer circumference of the pole piece to seal the coil and other internal components with the molding resin. It is being stopped. An example of an electromagnetic pickup that employs such a technique is disclosed in Japanese Utility Model Laid-Open No. 61-181321.

For this sealing, a sealing agent is applied to the sealing surface on the side of the pole piece in advance and a resin is molded on the outside, and the resin is sealed without the sealing agent. Either of the direct molding methods was adopted.

[0005]

In the case where a metal member such as a magnetic pole is directly covered with a resin, a gap is created at the interface between the resin and the metal member due to the difference in the coefficient of thermal expansion of the material, and the airtightness is deteriorated. Then, infiltration of water or the like occurs along the interface.

[0006] Further, the sealant using a sealant aims at absorbing the difference in thermal expansion by the sealant so as not to generate a gap at the interface, but in the conventional seal structure, a metal member is used. Since the encapsulant is applied to the straight surface of, the encapsulant often melts and flows out due to mold heat when the encapsulating resin is molded, which causes the encapsulant to fully function. Didn't.

An object of the present invention is to eliminate such drawbacks and improve reliability of hermetic sealing.

[0008]

In order to solve the above problems, according to the present invention, a resin is provided around a metal member such as a magnetic pole by molding, and the resin which is integrated with the metal member is provided inside. In the resin sealing structure for protecting the wrapped coil and other components, the resin contact surface of the metal member is provided with unevenness that surrounds at least one portion of the resin sealing portion.

In this sealing structure, it is desirable to interpose a thermoplastic resin sealant that adheres to both the metal member and the resin at the interface of the resin sealing portion.

The irregularities are preferably endless grooves or ridges. Further, it is desirable that the number thereof is plural, but the number may be one, and the shape may be a spiral groove or a ridge.

[0011]

When the surface of the metal member is made uneven and the sealant is applied thereto, the recess serves as a sealant reservoir, and the outflow of the sealant when the sealing resin is molded outside is suppressed. .

As a result, the sealant stops in the recess, and the elastic deformation of the sealant absorbs the difference in thermal expansion and contraction between the metal member and the sealing resin, so that no gap is created at the interface of the seal portion. .

[0013] Further, since the passage of water or the like becomes zigzag due to the installation of the unevenness and the length of the passage becomes long, it becomes difficult for water or the like to enter even when the sealant is omitted, and the sealing reliability is improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1A shows an example of an embodiment of a sealing structure of the present invention, which is adopted in an electromagnetic pickup of a rotation sensor.

The electromagnetic pickup shown in the figure is formed by molding a detector comprising a magnetic pole piece 1, a coil assembly 2, a magnet 3 and a yoke 4, a mounting bracket 5 and a signal output line 6 in a resin housing 7. The coil assembly 2 including the connection portion with the signal output line in the housing 7
It has a structure that covers.

In the coil assembly 2, a part of the magnetic pole piece 1, the magnet 3 and the yoke 4 are embedded in the molding resin 2a to be integrated with each other, and the coil 2c is attached to the bobbin 2b formed integrally with the molding resin 2a. The coil terminal 2d is wound and is embedded in the resin 2a. The coil 2c and the cover cover pipe 8 for protecting the barbed portion are fitted on the outside of the coil assembly 2 and the outside is covered with the housing 7.
The interface is sealed at the portion where the housing 7 is in close contact with the outer circumference of the pole piece 1.

The sealing portion is, as shown in FIG. 1 (b),
An annular groove 9 is provided on the outer circumference of the pole piece 1, a thermoplastic resin sealant 10 is applied in the groove 9, and then a resin for housing is molded outside the sealant 10. The sealing agent 10 is melted by the molding heat of the resin on the outside and adheres to the housing 7.

With such a structure, the groove 9 serves as a sealant reservoir and the sealant 10 stays in the groove during molding of the housing, and the sealant serves to maintain the stability of hermetic sealing. .

The groove 9 may be a V groove shown in FIG. 2 (a). Further, instead of the groove 9, the ridge 1 shown in FIG.
1 may be provided. Further, although the groove 9 and the protrusion 11 shown in the drawing are annular without an end, the spiral protrusion 1 shown in FIG.
It may be two or a spiral groove. Further, the groove or the ridge may be single or plural.

[0020]

As described above, according to the resin sealing structure of the present invention, the unevenness provided on the surface of the metal member prevents the sealing agent from flowing out, so that the function of the interface sealing by the sealing agent is achieved. It is surely exhibited and the reliability of hermetic sealing by the resin is improved.

In addition, when the intrusion route for water or the like is not straight due to the unevenness and the route length is extended, the sealing resin is directly molded on the outer periphery of the metal member without using the sealing agent. The reliability of hermetic sealing is enhanced.

[Brief description of drawings]

FIG. 1A is a cross-sectional view of an electromagnetic pickup adopting a sealing structure of the present invention. FIG. 1B is an enlarged view of a resin sealing portion of the same.

FIG. 2A is a diagram showing a modified example of the groove. FIG. 2B is a diagram in which a protrusion is provided instead of the groove. C is a diagram in which the protrusion is a spiral protrusion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 magnetic pole child 2 coil assembly 3 magnet 4 yoke 7 resin housing 9 annular groove 10 sealant 11 ridge 12 spiral ridge

Claims (2)

[Claims] 1. In a resin sealing structure which is provided by molding a resin around a metal member and protects a component which is integrated with the metal member and is wrapped in the resin, a resin contact surface of the metal member is provided. A resin encapsulation structure, characterized in that a concavo-convex pattern is formed around the resin encapsulation portion at least once. 2. A sealant made of a thermoplastic resin is interposed between the metal member and the resin in the uneven portion installation portion,
The resin sealing structure according to claim 1, wherein the sealing agent adheres to the metal member and the resin.