JPH03156302A - Linear type potentiometer - Google Patents

Abstract

PURPOSE:To make it possible to perform stable, accurate detection without causing the defective sliding of a shaft even if the center of the shaft does not agree with the centers of bearings by forming a swelled inner protruding shape for the surface of an inner cylinder which is slidden on the shaft of the bearings. CONSTITUTION:A bearing 1-b is fixed in a housing 1 by insert molding. A bearing 2-b is fixed in a cover 2 similarly by insert molding. Even if the center of a shaft 4 and the centers of the bearings 1-b and 2-b are inclined or deviation occures when the housing 1 and the cover 2 are assembled, large backlash does not occur for the shaft 4 with respect to the bearings 1-b and 20b, and the shaft is slidden smoothly. Therefore, the sliding operation characterized by smooth sliding and less backlash can be performed by only performing welding readily and simply without comprex steps such as adjustment and temporary fixing.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a linear potentiometer, which has recently been in increasing demand especially as a position detection sensor for automobiles.

(Prior Art) FIG. 3 shows a cross section of a conventional linear potentiometer 1, in which 1 is a housing, and a bearing 1-a is insert-molded in the housing 1.

2 is a cover, which includes a bearing 2-a similar to the housing 1;
is insert-molded and fixed to the housing 1 by heat welding. 3 is a brush mounting plate, and 4 is a shaft, which is integrated with the brush mounting plate by insert molding. 5 is a resistor, and 6 is a brush, which is fixed to the brush mounting plate 3 by caulking. Reference numeral 7 denotes a spring that pushes down the shaft 4 via the brush mounting plate 3, and this spring presses the shaft 4 against the detected portion (Ill not shown). Reference numeral 8 denotes a cap functioning as a stopper on the push-in side of the shaft 4, and 9 a lead wire, which is electrically connected to the resistor 5 and sealed with a sealant lO. Figure 4 shows bearings 1-a and 2 in Figure 3.
-a shows a cross section.

Next, the operation of the conventional linear potentiometer configured as described above will be explained. In Figure 3, axis 4
is at a certain position in the vertical direction depending on the mechanical position of the detected part. For this purpose, the brush 6 is placed in a certain position on the resistor 5 and a certain electrical output is obtained through the lead wire 9. As a result, an electrical output corresponding to the position of the shaft 4 can be obtained.

(Issue 1 to be solved by the invention! I) However, in the above conventional configuration, if the axes of the bearings 1-a and 2-a do not completely align with the axis of the shaft 4, the shaft Then, the bearings 1-a and 2-a do not slide smoothly, and the shaft 4 cannot be returned by the force of the spring 7 alone, resulting in a so-called "shafted" state, making it impossible to detect the accurate position of the detected part. Therefore, when assembling, the shaft 4 and bearing 1-
It was necessary to temporarily fix the cover 2 after adjusting the position of the cover 2 so that it could slide smoothly by combining a and 2-a, and then perform welding again for the final fixation. Even so, after final fixing, the positional relationship between the housing 1 and the cover 2 is often shifted due to the force applied during welding, resulting in poor sliding, and the housing 1 and the cover 2 are made of resin molded products. Therefore, there were problems such as poor sliding due to the annealing effect and thermal expansion after heat resistance.

The present invention solves the above-mentioned conventional problems.

It is an object of the present invention to provide a linear potentiometer that does not cause poor sliding of the shaft even if the axis of the shaft does not match.

(Means for Solving the Problems) In order to achieve the above object, the present invention is such that the inner cylindrical surface that slides on the shaft of the bearing has a convex shape that bulges inward.

(Function) Therefore, with the configuration of the present invention, even if the bearing is tilted relative to the shaft, the shaft and the bearing can slide smoothly without significantly increasing the clearance between the shaft and the bearing. This has the advantage that stable and smooth shaft sliding characteristics can be obtained, and the detected portion can be accurately detected.

(Embodiment) FIG. 1 shows a cross section of a linear potentiometer according to an embodiment of the present invention. In FIG. 1, the same symbols as in the conventional example of FIG. 3 indicate the same contents and have the same functions. 1-b and 2-b are bearings. A bearing 1-b is fixed to the housing 1 by insert molding, and a bearing 2-b is fixed to the cover 2 by insert molding. Figure 2 shows a cross section of bearing 1-b or 2-b, and the inner side of the bearing is convexly bulged.
The part of the bearing with the smallest hole diameter is larger than the shaft diameter by the amount of clearance.

Next, the operation of the embodiment configured as described above will be explained. In the embodiment described above, even if the axis of the shaft 4 and the axis of the bearings 1-b and 2-b are tilted or misaligned when the housing 1 and the cover 2 are combined, the shaft 4 is connected to the bearing 1-b. Since it slides smoothly against b and 2-b without any large play, you can simply weld it without going through complicated processes such as adjustment or temporary fixing, and the sliding is extremely smooth and there is little play. A sliding motion can be performed. Furthermore, the sliding force of the shaft remains extremely stable even if the resin molded product is distorted in a heat-resistant environment or under high or low temperatures.

As described above, according to this embodiment, by making the inside of the bearing 1-b in the housing 1 and the bearing 2-b in the cover 2 convex, it is extremely easy to slide even during assembly work and under high and low temperatures. Since the dynamic characteristics are stable, a linear potentiometer with accurate detection can be realized.

(Effects of the Invention) As is clear from the above embodiments, the present invention has an inner cylindrical surface that slides on the shaft of the bearing having a convex shape that bulges inward, so that the axis of the shaft and the axis of the bearing are misaligned. The shaft slides smoothly even when tilted or tilted, so it does not require adjustment or temporary fixing during assembly, and it has realized a linear potentiometer that allows stable and accurate detection of sliding characteristics even under high and low temperatures. It has the effect of being able to.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a structural sectional view of a linear potentiometer according to an embodiment of the present invention, Fig. 2 is a sectional view of the bearing shown in Fig. 1, and Fig. 3 is a structural sectional view of a linear potentiometer in a conventional example. Structural sectional view, FIG. 4 is a sectional view of the bearing of FIG. 3. 1- Housing, 1-a, 1-b, 2-a. 2-b...Bearing, 2...Cover 3...Brush mounting plate, 4...Shaft, 5...Resistor, 6...
Brush, 7... Spring, 8... Cap, 9.
...Lead wire, 10...Sealant.

Claims (1)

[Claims] a resistor, a brush that slides on the resistor, a brush mounting plate to which the brush is attached and has a shaft structure having a center line in the sliding longitudinal direction, and a position opposite to the brush in the sliding direction. A linear potentiometer comprising two bearings arranged in the same direction and each fixed to a different member, the inner cylindrical surface of which slides on the shaft of the bearing having a convex shape bulging inward. .