JPH0644879A - Proximity switch - Google Patents

Abstract

PURPOSE:To prevent a proximity switch including a coil case fitted in a case body from setting-off of the coil case out of the case body or breakage of a circuit board and/or electronic parts mounted thereon resulting from thermal expansion of a soft resin which is used to fill the inside for protecting the circuit board. CONSTITUTION:A coil case 2 fitted interiorly with a sensor part 3 is interiorly fitted at and supported by the front extremity of a case body 1, and a circuit board 4 furnished in the sensor part 3 is covered with a soft resin with which the case body 1 is filed. A cord 8 connected with the circuit board 4 and led out from the rear end of the case body 1 is sealed fast with a hard resin 14 as filling at the rear end of the case body 1, and a space 13 is formed between the soft resin material 10 and hard resin material 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a proximity switch used in a relatively high temperature environment.

[0002]

2. Description of the Related Art As a proximity switch, as shown in FIG. 5, a coil case 2 having a detection part 3 therein is internally fitted and supported at a front end of a cylindrical case body 1, and a circuit board provided in the detection part 3. 4 is covered with a soft epoxy resin material 10 filled in the case body 1 to protect the circuit board 4, and a cord 8 connected to the circuit board 4 and led out from the rear end of the case body 1 is attached to the rear side of the case body 1. It is known that the cord 8 is sealed by a hard epoxy resin material 14 filled at the end to surely support the cord 8 on the case body 1.

[0003]

In the above-described conventional proximity switch, the case body 1 is filled with the soft resin material 10 having a large thermal expansion coefficient and the hard resin material 14 having a small thermal expansion coefficient in close contact with each other. Therefore, when the soft resin material 10 thermally expands, the coil case 2 is pushed out from the front end of the case body 1, and the circuit board 4 and the electronic component 9 on the circuit board are damaged by the thermal stress of the soft resin material 10 itself. There was an occasion.

An object of the present invention is to prevent the occurrence of defects due to thermal expansion of such soft resin material.

[0005]

In order to achieve the above object, a proximity switch according to the present invention is provided with a coil case having a detection part internally fitted and supported at the front end of a cylindrical case body, and provided in the detection part. The circuit board is covered with a soft resin material filled in the case body, and the cord connected to the circuit board and led out from the rear end of the case body is sealed and fixed with a hard resin material filled in at the rear end of the case body. A space is formed between the soft resin material and the hard resin material.

[0006]

According to the above construction, even if the soft resin material covering the circuit board is thermally expanded, the space provided behind the resin material functions as an expansion absorption space for the resin material.

[0007]

1 is a sectional view of a proximity switch according to the present invention, and FIG. 2 is an external view thereof.

This proximity switch is provided in a case body 1 formed in a cylindrical shape, a coil case 2 which is internally fitted and fixed to a front end of the case body 1, a detection section 3 which is housed in the coil case 2, and a rear section of the detection section 3. Circuit board 4, housing 5 fitted in the rear part of case body 1, bushing 6 fitted in the rear end of case body 1, cord 8 connected to the printed circuit of circuit board 4 via clip terminal 7. , Are provided.

The case body 1 is made of a metal material and has a screw portion 1a for attaching to a mechanical device and a hexagonal operation portion 1b. The coil case 2 is formed in a cylindrical shape with a bottom, and the detection unit 3 including a core and a coil is incorporated therein. On the circuit board 4 soldered and fixed to the rear surface of the detection unit 3, various electronic components 9 forming a detection circuit are mounted, and the entire circuit board 4 is filled with a soft epoxy resin in the case body 1. It is sealed and protected by the material 10.

The housing 5 is oil-tightly fitted in the case body 1 through an O-ring 11 and positioned and supported by the step portion 1c in the case. The clip terminal insertion hole 12 formed in the housing 5 is liquid. It is oil-tightly sealed with rubber. A space 13 is formed between the housing 5 and the rear end of the epoxy resin material 10 for protecting the circuit board 4. Further, behind the housing 5, a hard epoxy resin material 14 is filled in the rear end of the case body 1 and inside the bush 6, and the cord 8 is fixedly supported. An annular groove 1d into which the epoxy resin material 14 is inserted is formed on the inner periphery of the rear end of the case body 1, and the housing 5, the bush 6, and the cord 8 are detached from the case body 1 when the epoxy resin material 14 is cured. Are being blocked. Further, the O-ring 11 prevents the hard epoxy resin 14 from entering the space 13 side during filling.

The proximity switch of the present invention is constructed as described above. Next, the manufacturing process thereof will be described with reference to FIG.

(A) As shown in FIG. 3 (a), a front end of the case body 1 is provided with a pre-assembled component having the coil case 2 in which the detection portion 3 is incorporated and the circuit board 4 to which the clip terminal 7 is connected. Insert more internally.

(B) After inserting the front end of the coil case 2 until it coincides with the front end of the case body 1, as shown in FIG. 3 (b), a predetermined position inside the case body 1 so as to cover the entire circuit board 4. The soft epoxy resin material 10 is filled.

(C) Next, as shown in FIG.
The housing 5 is inserted from the rear end of the case body 1 to a predetermined depth position, and the core wire of the cord 8 is connected and fixed to the rear end of the clip terminal 7 penetrating the housing 5 by soldering or the like.

(D) Next, the clip terminal insertion hole 12 of the housing 5 is sealed with liquid rubber, and as shown in FIG.
As shown in (d), the bush 6 is attached to the rear end of the case body 1.
Fit.

(E) After that, as shown in FIG. 3 (e), a hard epoxy resin material 14 is filled inside the rear end of the case body 1 and the bush 6 and cured.

[Other Embodiments] As shown in FIG. 4, the through terminal 1 to which the electric wire 15 extending from the circuit board 4 is connected.
The terminal 17 provided with 6 is fitted into the rear end of the soft epoxy resin material 10 at an appropriate interval to form the space 13, the core wire of the cord 8 is connected and fixed to the rear end of the through terminal 16, and then the case body 1 Alternatively, the rear part may be filled with the hard epoxy resin material 14.

[0018]

According to the present invention, even if a soft resin material having a high coefficient of thermal expansion expands, the expansion of the soft resin material is prevented in the space formed between the soft resin material and the hard resin material located behind it. As a result, it is possible to prevent situations in which the coil case is pushed out in the front of the case body and comes off, or the circuit board and electronic components are damaged by the thermal stress of the soft resin material. Now you can get a high proximity switch.

[Brief description of drawings]

FIG. 1 is a sectional view of a proximity switch according to the present invention.

FIG. 2 is an external perspective view of the entire proximity switch.

[Fig. 3] Assembly process diagram

FIG. 4 is a sectional view of another embodiment.

FIG. 5 is a sectional view of a conventional example.

[Explanation of symbols]

 1 Case Main Body 2 Coil Case 3 Detecting Part 4 Circuit Board 8 Code 10 Soft Resin Material 13 Space 14 Hard Resin Material

Claims (2)

[Claims] 1. A coil case containing a detection unit is internally fitted and supported at the front end of a cylindrical case body, and the circuit board provided in the detection unit is covered with a soft resin material filled in the case body, The cord that is connected and led out from the rear end of the case body is sealed and fixed with the hard resin material filled in at the rear end of the case body, and a space is formed between the soft resin material and the hard resin material. There is a proximity switch. 2. A partition housing is provided at the rear of the soft resin material via the space, and the hard resin material is provided at the rear of the soft resin material, and a ring-shaped sealing material is provided between the housing and the case body. The proximity switch according to claim 1, wherein the proximity switch is provided.