JPH1123210A - Linear potentiometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a linear potentiometer which can prevent the damage of a cover by a method wherein an elastic body is installed on the inner side face of a case at the cover which is faced with the coupling and stopping part of a shaft. SOLUTION: An elastic body 30 is installed on the inner side face of a case 21 at a cover 29 which is faced with the coupling and stopping part 25 of a shaft 24. The shaft 24 feeds a moving body 27 according to the movement amount of a detection part. When the moving body 27 is moved, the position of the resistance pattern on a board 26 of a brush 28 is changed, and its resistance value is changed. A detected resistance value is derived to the outside via a terminal 32 and a lead wire 33. In this state, when a sudden insertion force is generated at the shaft 24, the rear surface of the moving body 27 may collide with the elastic body 30 irrespective of the repulsive force of a spring 31. In this case, since the part is composed of the elastic body 30 by, e.g. a rubber, its collision force can be absorbed. Consequently, a large external force is not applied to the cover 29, the cover 29 is not damaged, and water or oil does not creep into the inside of the case 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear potentiometer used for a torque detector of an electric bicycle pedal, for example.

[0002]

2. Description of the Related Art A conventional linear potentiometer disclosed in a microfilm disclosed in Japanese Utility Model Laid-Open No. 2-56406 is known.

Hereinafter, a conventional linear potentiometer will be described with reference to the drawings. FIG. 2 is a side sectional view of a conventional linear potentiometer. A conventional linear potentiometer includes a case 3 having a through hole 1 on an upper surface and an opening 2 on a bottom surface, and a through hole 1 on an upper surface of the case 3.
A shaft 4 inserted so as to protrude outward from the inside of the case 3 through the inside of the case 1 and is provided substantially parallel to the shaft 4 in the case 1 and a resistance pattern (not shown) is provided on the surface thereof. A movable body 7 having a brush 6 fixed to the shaft 4 and sliding on a resistance pattern of the substrate 5, a cover 8 attached to the opening 2 on the bottom surface of the case 3, The configuration includes a spring 9 provided between the cover 8 and the movable body 7.

[0004]

However, in the above-mentioned conventional structure, the spring 9 is provided between the cover 8 and the movable body 7 so that the movable body 7 does not collide with the cover 8. Is pushed in at a high speed, the movable body 7 collides with the cover 8 due to its inertial force, and the cover 8 is damaged. If the cover 8 is damaged, water or oil may enter the case 3 and deteriorate the characteristics of the linear potentiometer.

An object of the present invention is to solve the above-mentioned conventional problems and to provide a linear potentiometer in which a cover is hardly damaged.

[0006]

In order to achieve the above object, the present invention provides an elastic member provided on an inner surface of a cover facing a movable member.

According to the present invention, a linear potentiometer in which the cover is hardly damaged can be obtained.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION
A case provided with a through hole on the top surface and an opening on the bottom surface,
A shaft having a locking portion inserted into the case through the through hole of the case, and a shaft provided in the case so as to be substantially parallel to a movement locus of the shaft, and a resistance pattern provided on a surface thereof; A movable body having a brush fixed to the shaft and sliding on the resistance pattern of the substrate; a cover attached to an opening of the case; and a cover provided between the cover and the movable body. A spring for applying a one-way urging force to the movable body, wherein an elastic body is provided on the inner surface side of the case of the cover facing the locking portion of the shaft, and the elastic body provides a shock. Since it absorbs, it has an effect that the cover and the like are hardly damaged.

(Embodiment) Hereinafter, a linear potentiometer according to an embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 21 denotes a cylindrical case made of a resin such as polybutylene terephthalate. A through hole 22 is provided on the upper surface of the case 21, and an opening 23 is provided on the bottom surface. . The engaging portion 25 of the stainless steel shaft 24 is inserted into the case 21 through the through hole 22. The locking portion 25 prevents the shaft 24 from coming out of the case 21 upward. On the other hand, a resistor substrate 26 is provided on the inner surface side of the case 21, and a resistance pattern (not shown) is provided on the surface of the substrate 26. And this substrate 26
The brush 28 is fixed to the movable body 27 so as to abut on the resistance pattern (not shown). The upper surface of the movable body 27 is in contact with the locking portion 25 of the shaft 24.
In this state, the opening 23 of the case 21 is closed by a cover 29 made of resin. The elastic body 3 made of rubber is provided on the inner side of the case 21 of the cover 29.
0 is attached. Further, a spring 31 is provided between the cover 29 and the movable body 27. Further, a terminal 32 is led out of the case 21 so as to be electrically connected to a conductive pattern (not shown) from the substrate 26 so as to penetrate the cover 29. A lead wire 33 is electrically connected to the terminal 32, and is sealed with a resin 34 in this state. The operation of the thus configured linear potentiometer according to one embodiment of the present invention will be described below. The shaft 2
4 moves the movable body 27 in accordance with the detected amount of movement, and the movement of the movable body 27 changes the position of the resistance pattern (not shown) of the brush 28, so that the resistance value changes and is detected. The resistance value is drawn out to the outside via the terminal 32 and the lead wire 33. In this state, if a sudden insertion force is generated in the shaft 24, the lower surface of the movable body 27 may collide with the elastic body 30 regardless of the repulsive force of the spring 31. Is an elastic body 30 made of rubber, for example, so that the collision force can be absorbed. No large external force is applied to the cover 29. Therefore, the cover 29 is not damaged and water or oil does not enter the case 21.

[0011]

As described above, according to the present invention, by providing an elastic body on the inner surface of the cover facing the movable body, the cover is not damaged even if the movable body collides with the cover. Has the effect of providing a linear potentiometer with improved characteristics that does not penetrate into the case.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a linear potentiometer according to an embodiment of the present invention.

FIG. 2 is a side sectional view of a conventional linear potentiometer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Case 22 Through-hole 23 Opening 24 Shaft 26 Resistor board 27 Movable body 29 Cover 30 Elastic body

Claims (1)

[Claims] A case provided with a through hole on an upper surface and an opening on a bottom surface; a shaft having a locking portion inserted into the case through the through hole of the case; A substrate provided in a substantially parallel relationship with the movement locus of the shaft, and a resistance pattern provided on the surface thereof;
A movable body having a brush fixed to the shaft and sliding on the resistance pattern of the substrate, a cover attached to an opening of the case, and the movable body provided between the cover and the movable body; A linear potentiometer comprising: a spring for applying a unidirectional urging force to a body; and an elastic body provided on an inner surface side of the case of the cover facing a locking portion of the shaft.