JPH1153979A - Duct cover for limit switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of cracks and prevent the entry of water and dust with simple and inexpensive structure. SOLUTION: This dust cover has a housing cover part 2 mounted on a limit switch main body-housing 11, and a boot part 3 for covering a moving part 12 of the limit switch 15 which is expanded and contracted. The boot part 3 contains a bellows 4 of at least one peak and one valley, covers the whole moving part 12 of a limit switch 15 containing the limit switch main body- housing 11, and the deformation of the moving part of the limit switch 15, such as a contact 14-plunger 13 is made possible by the deformation of the bellows 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a dust cover. More specifically, the present invention relates to a dust cover mounted on a movable portion of a limit switch.

[0002]

2. Description of the Related Art As means for waterproofing and dustproofing a conventional limit switch, a dust cover is mounted between a sliding member of a movable part and a fixed member, and a waterproof seal is provided near an electric contact in a switch housing. There is one that is provided with. For example, in the case of the limit switch 101 which is operated by the reciprocating motion of the plunger in the axial direction, as shown in FIG.
And a dust cover 105 is attached between the
Only 3 is exposed. Dust cover 10
Reference numeral 5 denotes a cylindrical shape in which a cylinder and a cone are connected, and the cylindrical portion 106 has a fixed cylindrical portion 10 of the housing 104.
8, the conical portion 107 is attached to the sliding plunger 102, and the plunger 102 can be moved by deformation at the base portion of the conical portion 107, that is, near the boundary 109 between the conical portion and the cylindrical portion.

[0003]

However, since the contact portion 103 is exposed from the dust cover 105,
If the tightening force of the dust cover 105 is reduced or the fastening surface is damaged, the dust cover 105 and the plunger 1 are damaged.
There is a problem that water and dust intrude from the fitting portion with the 02. Further, as the plunger 102 moves up and down, the dust cover 105 is deformed by largely bending the vicinity 109 of the base of the conical portion 107, so that a crack is easily generated near the boundary 109, and water and dust are generated therefrom. There is a risk of intrusion. Therefore, it is necessary to provide a waterproof seal inside the housing of the limit switch, which is expensive. Further, since the cover covers only the periphery of the plunger 102 and the upper part of the cylinder part 108, there is a possibility that rust is generated on the exposed surface of the lower part of the cylinder part 108 and the housing 104.

[0004] It is an object of the present invention to provide a dust cover for a limit switch in which cracks are less likely to occur and water and dust are less likely to enter. Another object of the present invention is to provide an inexpensive limit switch dust cover that can prevent intrusion of water or dust with a simple structure.

[0005]

In order to achieve the above object, a dust cover for a limit switch according to the present invention covers a whole movable portion including a limit switch body in a dust cover mounted on a movable portion of the limit switch. ,
In addition, it has at least one peak or one valley bellows.

Therefore, when the movable portion of the limit switch is moved by the mating member, it can be displaced by expansion and contraction and deformation of the bellows portion. In addition, since the movable portion and the limit switch body are entirely covered by the dust cover, they are protected from intrusion of water and dust between the movable portion and the housing.

According to a second aspect of the present invention, there is provided a dust cover for a limit switch, wherein a protrusion protruding inward is provided at an edge of an opening of a housing cover portion covering the limit switch body. In this case, when the housing cover is extended and put on the housing of the limit switch main body, even if the opening of the housing cover partially expands, the protrusion contacts the housing of the limit switch main body to maintain the surface pressure, Water and dust can be prevented from entering there.

Further, a dust cover for a limit switch according to a third aspect of the present invention has a bag-shaped boot portion for covering a movable portion of the limit switch, and a top portion of the boot portion with which a contact of the limit switch comes into contact is at least a bellows portion. The thickness is increased. In this case, it is possible to prevent a decrease in the durability of the top of the boot portion due to the impact of the opponent member, and to prevent sound generation due to the contact.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described below in detail based on one embodiment shown in the drawings.

FIG. 1 shows an embodiment of a dust cover for a limit switch according to the present invention. The dust cover 1 for the limit switch is composed of the limit switch body / housing 1
1 is provided with a housing cover part 2 which is put on the boot 1 and a bag-shaped boot part 3 which is put on the movable part 12 of the limit switch 15. Although the dust cover 1 is not limited to a specific material, it is preferable to use an elastomer material such as chloroprene rubber or ethylene propylene rubber, and the housing cover portion 2 and the boot portion 3 are integrally formed.

The boot portion 3 comprises a bellows portion 4 which covers the plunger 13 of the limit switch 15 and a top portion 5 with which the contact 14 of the limit switch comes into contact. The bellows portion 4 has at least one peak or one valley, and is formed to be extendable and contractible in the direction in which the plunger 13 of the limit switch moves. In the case of the present embodiment, the bellows portion 4 having substantially two peaks is formed much thinner than the housing cover portion 2,
The top 5 is supported movably in the same direction as the contact 14 and the plunger 13 by the expansion and contraction and deformation of the bellows 4. The top portion 5 is at least thicker than the bellows portion 4 and is provided so as not to be worn and broken by contact with a mating member (not shown) and not to sound. Specifically, the top portion 5 is formed to be the thickest in the dust cover 1. Then, the inner surface 6 of the top 5 which contacts the contact 14
Is formed into a spherical surface and is designed so that the contact point 14 formed of a roller does not bite. The outer shape 7 of the top 5 does not need to be a specific shape, but is formed as a truncated conical surface by cutting off the top of the cone and forming a flat plane. On the other hand, the bellows portion 4 is formed to have a small thickness, and the portion is preferentially deformed so that the boot portion 3 can easily expand and contract without a load.

The housing cover 2 has an inner surface that is in close contact with the outer shape of the limit switch. For example, in the case of the illustrated embodiment, the limit switch body / housing 11
Is formed in a rectangular box shape that covers the upper part, and the opening 8 is formed with a protrusion 9 protruding inward. The protrusion 9 has a shape of the opening 8 swelled and the limit switch body / housing 1.
This is for preventing a gap from being generated between the first and second members, and is formed at least at an edge of a side in the longitudinal direction. Therefore, even when the opening 8 of the housing cover 2 is partially expanded when the housing cover 2 is extended and put on the limit switch main body / housing 11, the projection 9 contacts the limit switch main body / housing 11 and the surface thereof is in contact with the limit switch main body / housing 11. The pressure is maintained and water and dust can be prevented from entering there. Inside the housing cover 2, there is formed a minute vertical groove 10 for venting air from the edge of the opening 8 to the boot 3. Thereby, when the contact 14 (plunger 13) of the limit switch 15 is pressed and the bellows portion 4 is deformed, the pressure fluctuation accompanying the volume change of the bellows portion 4 is suppressed by the inflow and outflow of air, and the contact 1
The boot 4 is provided so that the movement of the boot 4 is not hindered.

The top 5 is made thicker so that it does not break even when worn, and has sufficient hardness. Therefore, limit switch 1
The top 5 is prevented from rotating (swinging) due to the rotation of the roller (contact point) 14 at the tip of 5, and the bellows 4 is prevented from biting the roller. Here, the inner surface 6 is not particularly limited to a spherical surface, and may be formed as a cylindrical surface that is curved in the hoop direction (circumferential direction) of the roller and flat in the axial direction.

The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention. For example, in the present embodiment, a roller plunger type limit switch having a roller at the tip of the plunger has been mainly described. However, the present invention is not particularly limited to this, and various types such as a simple plunger type without a roller, a roller lever type, a lever type, etc. Applicable to limit switches. In any case, the shape is such that it covers the entire movable portion including the housing of the limit switch and has at least one peak or one valley bellows portion. Further, in the present embodiment, the housing cover 2 of the dust cover 1 covers only the upper part of the limit switch main body / housing 11, but the present invention is not particularly limited thereto, and the housing 11 may cover the entire housing 11. In this case, it is possible to prevent not only the intrusion of water and dust between the housing 11 and the movable portion 12, but also the intrusion of water and dust from the dividing surface of the housing 11 itself. Further, in the present embodiment, the groove 10 is formed in a straight line, but is not particularly limited to this, and may be a labyrinth such as a crank shape. In this case, the effect of preventing intrusion of water and dust can be enhanced.

[0015]

As is apparent from the above description, the dust cover for the limit switch of the present invention covers the entire movable part including the main body and the housing of the limit switch, and covers at least one peak or one valley bellows. Because we have
The movable portion of the limit switch can be displaced by the expansion and contraction of the bellows portion, and cracks due to bending fatigue can be prevented. Moreover, since the movable part and the limit switch body are entirely covered by the dust cover,
It is completely protected from ingress of water and dust, and there is no need to provide a waterproof seal inside the limit switch, which can significantly reduce costs.

According to the second aspect of the present invention, since the protrusion protruding inward is provided at the edge of the opening of the housing cover that covers the limit switch main body, the housing covered by the main body / housing of the limit switch is provided. Even if the opening of the cover is partially expanded, the projections are in contact with the housing to maintain the surface pressure, thereby preventing intrusion of water and dust therefrom.

Further, according to the third aspect of the present invention, there is provided a bag-shaped boot portion which covers the movable portion of the limit switch, and the thickness of the top portion of the dust cover which contacts the contact point of the limit switch is at least thicker than the bellows portion. As a result, it is possible to prevent a decrease in durability and pronunciation.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a state in which a dust cover of the present invention is mounted on a limit switch, and shows a longitudinal section of the dust cover.

2A and 2B are views showing an embodiment of a dust cover for a limit switch according to the present invention, wherein FIG. 2A is a longitudinal sectional view, FIG. 2B is a sectional view taken along the line II-II of FIG. FIG.

3A and 3B are front views of a conventional limit switch with a dust cover, wherein FIG. 3A shows a state before a contact is pressed, and FIG. 3B shows a state where the dust cover is bent when the contact is pressed. .

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dust cover 2 Housing cover part 3 Boot part 4 Bellows part 5 Top part 8 Opening part 9 Protrusion 10 Groove 11 Limit switch housing 12 Limit switch movable part 13 Limit switch plunger 14 Limit switch contact

Claims (3)

[Claims] 1. A dust cover mounted on a movable portion of a limit switch, wherein the dust cover covers the entire movable portion including a limit switch body and has at least one peak or one valley bellows portion. Dust cover. 2. The dust cover for a limit switch according to claim 1, wherein a protrusion protruding inward is provided at an edge of an opening of a housing cover that covers the limit switch body. 3. A device according to claim 1, further comprising a bag-shaped boot portion covering a movable portion of said limit switch, wherein a top portion of said boot portion to which a contact point of said limit switch contacts is thicker than at least said bellows portion. The dust cover for a limit switch according to claim 1 or 2.