JPH0743881Y2 - Limit switch switch seal structure - Google Patents

Description

<Detailed Description of the Invention><Field of the Invention> This invention discloses a limit switch having a cemented carbide chip holder for holding a cemented carbide chip abutting against an object to be detected, which is fixed to the front end of an operating shaft for opening and closing the switch. The present invention relates to a seal structure.

<Prior Art and Problem> As a conventional switch of this type, as shown in FIG. 2, a bearing 104 is fixed to a switch case 103 accommodating light emitting and light receiving elements 101 and 102, which are arranged to face each other. The carbide chip holder 106 is fixed to the operating body 105 arranged on the same axis, the return coil spring 107 is interposed between the bearing 104 and the carbide chip holder 106, and the light emitting element 101 and the light receiving element 102 are provided. The working shaft 109 having a shutter 108 for opening and closing the optical path between the two is pressed into the central hole 110 of the cemented carbide chip holder 106 and fixed, and is rotatably supported by the bearing 104, and the cemented carbide chip holder 106 Recess 1 formed on the front
There is one in which a cemented carbide chip 112 is fitted to 11 and is fixed to the front end surface of the operating shaft 109 via an adhesive 113, and a rubber cap 114 seals between the operating body 105 and the switch case 103.

That is, this is because when the object to be detected hits the carbide chip 112, the operating shaft 109 pivots backward against the spring force of the return coil spring 107, and the optical path between the light emitting element 101 and the light receiving element 102. Is closed and the object to be detected is separated from the cemented carbide chip 112, the optical path is opened by the reverse operation.

By the way, in this type of switch, it is necessary to secure the sealing property between the operating shaft 109 and the cemented carbide chip 112. In the above-mentioned conventional one, the operating shaft 109 is formed in the central hole of the carbide chip holder 106.
Although it is press-fitted and fixed to the 110, since there is a minute gap between the two 109 and 110, the press-fit length l of the operating shaft 109 must be increased in order to obtain a sealing property. Since the thickness of the carbide chip holder 106 in the axial direction is large, it is difficult to reduce the size.

Further, although the adhesive 113 provides the sealing property between the carbide chip holder 106 and the operating shaft 109, it is troublesome to handle, and if the adhesive 113 thermally expands, the sealing performance of this part is strongly deteriorated. To be

Further, the above-mentioned conventional one has the front end portion 114 of the rubber cap 114.
a is fitted in the groove 106a at the front of the carbide chip holder 106
With the shape ring 114, the rear end brim of the carbide chip holder 106
Since it is held between 106a and the operating body 105, the E-shaped ring 1
Depending on the fitted state of 14, the front end portion 1 of the rubber cap 114
The holding force with respect to 14a varies, and it becomes difficult to obtain stable sealing performance.

<Purpose of Invention> This invention was made in order to solve the problems of the above-mentioned conventional ones, and it is possible to improve the sealing performance without temperature change.
It is an object of the present invention to provide a limit switch seal structure that can be downsized and is easy to manufacture.

<Structure and Effect of the Invention> The seal structure of the limit switch according to the present invention has an operating shaft penetratingly held on the front wall side of the switch case so as to be axially movable, and a cemented carbide arranged coaxially with the operating shaft. A chip holder, a carbide tip holder arranged coaxially with the operating shaft, a washer clamped and fixed between the step formed on the operating shaft and the rear surface of the carbide chip holder; A cemented carbide chip held on the front side of the rigid chip holder, and a rubber cap for sealing arranged over the cemented carbide chip holder and the front wall of the switch case are provided. The cemented carbide chip holder is fitted into a central hole and fixed by welding, and the cemented carbide chip is press-fitted and fixed in a recess formed in the front surface of the cemented carbide chip holder, and the front end portion of the rubber cap is bonded to the above-mentioned Hard chip ho It is tightened and fixed between the rudder and the above washer.

According to this invention, since the working shaft is fixed to the carbide chip holder by welding, the adhesion between the central hole of the carbide chip holder and the working shaft is increased, and the thickness of the above-mentioned carbide chip holder is reduced to achieve downsizing. Further, since the cemented carbide chip is easily fixed and no adhesive is used, the number of steps is reduced, and the sealing property is secured without being affected by heat. Also, since the front end of the rubber cap is tightened and fixed by the washer clamped and fixed by the step portion of the carbide tip holder and the operating shaft and the above-mentioned carbide tip holder, a tightly fixed state of this part can be obtained and sealing performance is obtained. Is increased.

<Description of Embodiments> An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an example of a seal structure of a limit switch according to the present invention.

In the figure, reference numeral 1 denotes a switch case composed of a case body 2 and a cover 3, inside which light emitting and light emitting elements 4 and 5 which face each other are housed. A bearing 7 is fixed to the bottom wall of the recess 6 formed in the cover 3. 8 is a cemented carbide chip holder arranged coaxially with the bearing 7, 9
Is a return coil spring interposed between the carbide chip holder 8 and the bearing 7. Reference numeral 10 denotes an operating shaft rotatably supported by the bearing 7, and a rear end face thereof is a shutter 11 for opening and closing an optical path between the light emitting element 4 and the light emitting element 5.
Is projected.

Reference numeral 12 is a central hole formed in the cemented carbide chip holder 8. The front end portion 10a of the operating shaft 10 is formed to have a small diameter, is fitted into the central hole 12, and is fixed to the cemented carbide chip holder 8 by laser welding. Numeral 13 is a washer penetrating the front end portion 10a of the operating shaft 10 and is sandwiched and fixed between the step portion 14 of the operating shaft 10 and the rear surface of the cemented carbide chip holder 8. Reference numeral 15 denotes a cemented carbide chip, which is press-fitted and fixed in a recess 16 formed in the front surface of the cemented carbide chip holder 8. Numeral 17 is a seal rubber for sealing between the cemented carbide chip holder 8 and the switch case 1 side, and a front end portion 17a thereof is fitted into an annular groove 18 formed on the rear surface of the cemented carbide chip holder 8 so that the washer 13 The rear end portion 17b is fixed to the inner surface of the bottom wall of the recess 6 with a fixing ring 19.

In the above structure, when the object to be detected hits the cemented carbide chip holder 15, the operating shaft 10 and the cemented carbide chip holder 8 axially move rearward against the spring force of the return coil spring 9, and the shutter 11 causes the light emitting element 4 to receive light. The optical path to the element 5 is closed,
When the object to be detected is separated from the cemented carbide chip 15, the operation shaft 10 is returned to the front by the operation opposite to the above, and the optical path is opened.

Here, since the front end portion 10a of the operating shaft 10 is fitted into the central hole 12 of the cemented carbide chip holder 8 and fixed by laser welding, the contact between the operating shaft 10 and the inner wall of the central hole 12 is smaller than that of the press-fitting structure. The property is enhanced and a tight fixing state is obtained. Therefore, the fixed length 1 of the operating shaft 10 and the cemented carbide chip holder 8 can be reduced, in other words, the thickness of the cemented carbide chip holder 8 in the axial direction can be reduced to make it compact.

In addition, the cemented carbide chip 15 is replaced by the recess 16 of the cemented carbide chip holder 8.
Since it can be fixed by press-fitting in and the sealing property can be obtained without using an adhesive, a troublesome handling step of the adhesive can be omitted and the production efficiency can be improved. Further, there is no problem of deterioration of sealing property due to thermal expansion of the adhesive, in other words, good sealing performance can be secured regardless of temperature change.

Further, the front end portion 17a of the rubber cap 17 is connected to the step portion 14 of the operating shaft 10.
Washer 13 that is sandwiched and fixed between and the carbide chip holder 8
As a result, the cemented carbide chip holder 8 is tightened and fixed, so that the tightening force is constant, there is little variation in the fixing state of this portion, and the sealing performance can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a seal structure of a limit switch according to the present invention, and FIG. 2 is a sectional view showing a seal structure of a conventional limit switch. DESCRIPTION OF SYMBOLS 1 ... Switch case, 8 ... Carbide chip holder, 10 ... Operating shaft, 12 ... Central hole, 13 ... Washer, 14 ... Step part, 15 ... Carbide chip, 16 ... Recessed part, 17 ... Rubber cap, 17a ... Rubber cap front end part.

Claims (1)

[Scope of utility model registration request] 1. A working shaft axially movably held through a front wall of a switch case, a cemented chip holder coaxially arranged with the working shaft, and a step formed on the working shaft. And a washer which is sandwiched and fixed between the rear surface of the cemented carbide chip holder and a cemented carbide chip held on the front side of the cemented carbide chip holder, and between the cemented carbide chip holder and the front wall of the switch case. And a rubber cap for sealing that is disposed straddling, and the front end of the operating shaft is fitted into a central hole formed in the cemented carbide chip holder and fixed by welding.
The cemented carbide chip is press-fitted and fixed in a recess formed in the front surface of the cemented carbide chip holder, and the front end of the rubber cap is clamped and fixed between the cemented carbide chip holder and the washer. The limit switch has a seal structure.