JPH056625U - Proximity switch - Google Patents

Abstract

(57) [Summary] [Purpose] To obtain a proximity switch that has good workability and that can securely fix the plug to the case. [Structure] A case 1 in which a detection unit 5, a printed circuit board 6 and the like are inserted from an opening 2, and a plug 10 including a body 11 and a flange 12 fitted in the opening 2 of the case 1, A recess 13 is formed on the rear end surface of the flange 12 of the plug 10.
And the holding portion 1 for the cable 7 is provided in the recess 13.
5, the resin injection hole 17 and the air vent hole 18 are provided.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a proximity switch for detecting presence / absence, movement, quantity, etc. of an object to be detected, and more particularly to an assembly structure of the proximity switch.

[0002]

[Prior Art]

 A proximity switch usually consists of a detection coil, a detection circuit section consisting of an oscillation circuit, a detection circuit, a switching circuit, an amplification circuit, etc., and a cable forming a power supply line and a signal line. Since the oscillation state of the oscillation circuit changes when the object to be detected approaches, the detection circuit detects this change and activates the switching circuit, which amplifies this and outputs it as a detection signal from the cable. It is a thing.

FIG. 3 is a vertical sectional view showing an example of a conventional proximity switch. In the figure, reference numeral 1 denotes a cylindrical case with a bottom, which is made of synthetic resin and has an opening 2 at the rear portion, and a male screw 3 for mounting is provided on the outer peripheral portion. There is. The inner diameter of the opening 2 is slightly larger than the inner diameter, and the step 4 is provided. Reference numeral 5 is a detection coil housed in the front end of the case 1, 6 is a printed circuit board which is mechanically coupled to the detection coil 5 and electrically connected thereto, and is provided with an oscillation circuit and the like (not shown). ..

Reference numeral 20 denotes a plug including a cylindrical body portion 21, a flange portion 22 and a holding portion 23 for the cable 7. The outer diameter of the body portion 21 is formed to a size capable of being fitted into the opening 2 of the case 1. One or a plurality of retaining slots 24 are provided. Reference numeral 25 is a resin injection hole provided in the flange 22, and 26 is an air vent hole.

In order to assemble the proximity switch as described above, first, the detection coil 5 and the punt substrate 6 are mechanically and electrically coupled to each other, and the cable 7 in which the holding portion 23 of the plug 20 is inserted is printed on the printed circuit board. 6 and the detection coil 5 and the printed circuit board 6 are accommodated in the case 1 through the opening 2. Then, the molten synthetic resin 8 is injected into the case 1 until the vicinity of the end of the opening 2 is reached, the plug 20 is advanced along the cable 7 and fitted into the opening 2, and the detection coil 5 and the print are printed. The board 6 and the plug 20 are integrally connected to the case 1. At this time, the tip of the body 21 of the plug 20 contacts the step 4 of the case 1, and the flange 22 contacts the rear end of the opening 2. Further, the resin injection hole 25 acts as an air vent hole.

As another assembling procedure, after the detection coil 5 and the printed circuit board 6 are housed in the case 1, the molten resin 8 is injected to the vicinity of the rear end portion of the printed circuit board 6 to detect the detected coil 5 The printed circuit board 6 and the case 1 are integrally connected. Then, the plug 20 is advanced along the cable 7, and the body portion 21 thereof is fitted into the opening 2 of the case 1. In this state, the resin 8 is injected from the resin injection hole 25, and the space formed between the already injected resin 8 and the plug 20 is filled with the resin 8 to integrally connect the plug 20 and the case 1. In any case, the resin 8 is filled in the retaining long hole 24 to firmly connect the case 1 and the plug 20 and prevent the plug 20 from coming off or rotating.

[0007]

[Problems to be solved by the device]

 In the conventional proximity switch as described above, when the former assembly procedure is used, air is likely to remain inside the case 1 and the plug 20, and it is difficult to completely fill the resin. Therefore, the moisture resistance is poor. Also, the built-in detection coil 5 and the printed circuit board 6 may move, and the plug 20 may rotate or come off. In the latter case, the resin is relatively well filled, but the resin must be injected just before it overflows from the small resin injection hole, so it is necessary to pay close attention to it, which causes the problem of poor workability. is there.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a proximity switch which has good workability and can securely fix the detection coil, the printed circuit board and the plug. Is.

[0009]

[Means for Solving the Problems]

 The proximity switch according to the present invention comprises a body and a flange that are fitted into the opening of the case, and a recess is provided on the rear end surface of the flange, and the recess holds a resin that penetrates the holder and the body of the cable. It is equipped with a plug provided with an injection hole and an air vent hole.

[0010]

[Action]

 Insert the printed circuit board to which the detector and cable are connected from the opening of the case, and inject the resin to near the rear end of the printed circuit board. Then, insert the body of the plug into the opening of the case and inject the resin from the resin injection hole. When the resin overflows from the resin injection hole and collects in the recess, and the upper surface of the resin injection hole is almost at the same height as the edge, the injection is stopped.

[0011]

【Example】

 1 is a sectional view and a rear view of an embodiment of the present invention, and FIG. 2 is an exploded perspective view thereof. The same parts as those in the conventional example of FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted. Reference numeral 10 denotes a plug including a body portion 11 that is fitted into the opening 2 of the case 1 and a flange portion 12 that abuts against an end portion of the opening portion 2. Has been formed. Reference numeral 15 is a holding portion for the cable 7 provided so as to project from the center of the recess 13, and 16 is a fixing hole for the cable 7 provided in the center of the body 11. Reference numeral 17 is a resin injection hole penetrating from the concave portion 13 to the body portion 11 side, and 18 is also an air vent hole.

Next, an example of the assembling procedure of the present invention configured as described above will be described. First, the detection coil 5 and the printed circuit board 6 are mechanically and electrically coupled to each other, the cable 7 inserted from the holding portion 15 of the plug 10 is connected to the printed circuit board 6, and the detection coil 5 and the printed circuit board 6 are opened. From 2 to the case 1. Then, the molten resin 8 is injected from the opening 2 to the vicinity of the rear end of the printed circuit board 6, and the detection coil 5 and the printed circuit board 6 are integrally connected to the case 1.

Next, the plug 10 is advanced along the cable 7, the body portion 11 of the plug 10 is fitted into the opening portion 2 of the case 1, and the plug portion 10 is pushed in until the tip portion comes into contact with the rear portion 4 of the case 1. As a result, the flange portion 12 comes into contact with the end portion of the opening 2 of the case 1. When the molten resin 8 is injected from the resin injection hole 17 in this state, the resin 8 is filled in the fixing hole 16 of the cable 7 between the resin 8 and the plug 10 which are already filled. When the resin 8 is further filled, the resin 8 overflows from the resin filling hole 17 and the air vent hole 18 and collects in the recess 13. Then, the filling is stopped when the upper surface of the resin 8 accumulated in the concave portion 13 becomes substantially the same height as the edge portion 14. It should be noted that the air in the case 1 is discharged to the outside from the air vent hole 18 as the resin 8 is filled, and there is no possibility that it will remain in the resin as air bubbles.

The resin 8 thus filled in the case 1 and the plug 10 is hardened to securely hold and fix the detection coil 5, the printed circuit board 6, the plug 10 and the cable 7 at a predetermined position. .. In particular, since the front and rear surfaces of the plug 10 are firmly fixed by the recess 13 and the resin injection hole 17 and the air vent hole 18 that communicate the recess 13 with the case 1, there is no risk of the plug 10 coming off or turning.

In the above description, the case where the circular recess 13 concentrically with the flange 12 is provided on the rear surface of the flange 12 of the plug 10, but the recess 13 may have an elliptical shape or other shapes. .. Further, although the case where the holding portion 15 of the cable 7 is projected from the central portion of the recess 13 is shown, it may be provided at a position deviated from the central portion as in the conventional example in FIG. The hole 17 and the air vent hole 18 may also be provided at appropriate positions around the holding portion 15. However, in order to surely fix the plug 10 to the case 1, it is desirable to place both in symmetrical positions.

In the above description, the present invention is applied to the oscillation type proximity switch, but the present invention can be applied to the electrostatic capacity type proximity switch in the same manner.

[0017]

[Effect of the device]

 As is clear from the above description, the present invention has a recess formed in the rear end surface of the flange portion of the plug, and the resin is injected into the case from the resin injection hole penetrating the recess. A remarkable effect can be obtained. (1) It is only necessary to stop the resin injection when the resin overflowing from the resin injection hole and accumulated in the recess reaches approximately the same height as the edge of the recess, so there is no need to pay close attention to the resin injection. Workability can be greatly improved. (2) Since the resin injection status can be visually confirmed, it is possible to obtain a proximity switch with improved quality and excellent environmental resistance. (3) After the resin is cured, the plug is fixed from both sides through the resin injection hole and the air vent hole, so the plug will not come off or rotate. Further, unlike the conventional case, it is not necessary to provide the withdrawal slot in the body portion, so that the mold manufacturing of the plug is facilitated and the mold manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view and a rear view of an embodiment of the present invention.

FIG. 2 is an exploded perspective view of FIG.

FIG. 3 is a sectional view and a rear view of a conventional proximity switch.

[Explanation of symbols]

 1 Case 2 Opening 5 Detection Coil 6 Printed Circuit Board 7 Cable 8 Resin 10 Plug 11 Body 12 Flange 13 Recess 15 Cable Retaining 17 Resin Injection Hole 18 Air Venting Hole

Claims (1)

[Claims for utility model registration] 1. A cylindrical case having an opening and containing a detection unit, a printed circuit board, etc., and a plug for holding a cable and closing the opening of the case. In the proximity switch in which the case is filled with resin, the plug includes a body portion and a flange portion that are fitted into the opening portion of the case, and a concave portion is provided on a rear end surface of the flange portion. A proximity switch characterized in that a resin injection hole and an air vent hole are provided through the cable holding portion and the body portion.