JPS62297734A - Optical temperature sensor - Google Patents

Abstract

PURPOSE:To obtain a temperature sensor consisting of a small number of components by pressing up an optical fiber directly by part of shape memory alloy and also using a two-directional coil spring. CONSTITUTION:An optical fiber 11b is fixed in a V groove 12 and a fiber 11a is pressed into the groove 12 near its tip by a leaf spring 16. Then, one terminal of torsional coil spring type two-directional shape memory alloy 15 is fixed to a main body 1 and the other terminal pressure the optical fiber 11a against the leaf spring 16 above certain temperature. Consequently, the terminal of the alloy 15 which is not fixed does not contact the optical fibers at the room temperature, so the fiber 11a is pressed into the V groove 12 by the spring 16 and the optical axes of the fibers 11a and 11b are aligned with each other. The alloy 15 is to change its shape above the certain temperature and pressure up the tip of the fiber 11a and the spring 16, so that the optical axes of the fibers 11a and 11b are not aligned any more with each other. Thus, light in the fibers 11a and 11b is transmitted and intercepted about the certain temperature.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention Field of Industrial Application The present invention relates to an optical temperature sensor used for overheat monitoring and the like.

2. Description of the Related Art Conventionally, this type of optical temperature sensor has a configuration as shown in FIG. In Fig. 3, la and lb are optical fibers, 2 is a V-groove, 3 is a movable member, 4 is a coil spring, and 5 is a coil spring-like unidirectional shape memory alloy, which attempts to assume an elongated shape above a certain temperature. . 6 is a leaf spring.

The operation of the optical temperature sensor configured as above will be explained below. The optical fiber 1b is fixed in the V-groove 2. The optical fiber 1a faces the optical fiber 1b within the V-groove 2, and its tip is not fixed to the groove 2.
At room temperature, it is pressed against the V-groove 2 by the leaf spring 6. Therefore, at room temperature, the optical axes of the two optical fibers 1 coincide within the groove and are optically coupled. However, when the temperature rises above a certain level, the shape memory alloy 5 tries to take on an elongated shape, compressing the coil spring 4, pushing up the movable rod 3, and the movable rod 3 pushing up the optical fiber 1a, thereby connecting the two optical fibers. The optical axes of la and lb do not match, and light is blocked. Next, when the temperature decreases to below a certain temperature, the force of the shape memory alloy 5 to take the stretched shape disappears, and it is contracted by the force of the coil spring 4, the movable member 3 is lowered, and the optical fiber 1a is suspended from the temporary spring. 6 to the V-groove 2, and the two optical fibers la and lb are optically coupled again. The above functions as a light temperature sensor.

Problems to be Solved by the Invention In such a conventional configuration, the movement of the shape memory alloy 5 is converted into the movement of the movable member 3, and since the unidirectional shape memory alloy 5 is used, the There was a problem that the number of points increased.

The present invention solves these problems by realizing a temperature sensor that does not use any movable members and has a small number of parts.

Means for Solving the Problem In order to solve this problem, the present invention provides a groove in which one of two optical fibers, which are provided in the same groove and whose end faces face each other, is grooved with an elastic member. It is pressed in and pushed out of the groove within a certain temperature range by the other end of a torsion coil spring-like bidirectional shape memory alloy whose one end is fixed.

Operation With this configuration, the optical fiber is directly pushed up by a part of the shape memory alloy, and since a bidirectional coil spring is used, no movable member or bias spring is required, and an optical temperature sensor with fewer components can be constructed.

Embodiment FIG. 1 is a perspective view of an optical temperature sensor according to an embodiment of the present invention. In FIG. ,
The first optical fiber llb is fixed in the V-groove 12, and the second optical fiber 11a is fixed in the V-groove 12 except for the tip.
It is fixed to the groove 1 with a temporary spring 16 near the tip.
It is pressed down inside 2. 15 is a torsion coil spring type 2
It is a directional shape memory alloy, and one end is fixed to the main body 17, and the other end is connected to the optical fiber Ila at a certain temperature or higher.
is pushed up against the leaf spring 1G.

The operation of the optical temperature sensor configured as above will be explained below. FIG. 2 is a front view of an optical temperature sensor according to an embodiment of the present invention. At room temperature (as shown in Figure b1, the unfixed end of the shape memory alloy 15 is not in contact with the optical fiber, so the optical fiber lla is held down in the groove 12 by the plate spring 16, Book optical fiber 11a.

The optical axes of 11b coincide. However, when the temperature exceeds a certain temperature, the shape memory alloy 15 tries to change its shape (as shown in Figure 81, it pushes up the tip of the optical fiber lla and the leaf spring 16, and the optical axes of the two optical fibers lla and llb no longer match). When the temperature drops again, the shape memory alloy 15 returns to its original shape, and (1)) the two optical fibers l as shown in the figure.
The optical axes of la and llb coincide. The above operation functions as an optical temperature sensor that transmits or blocks light in the optical fibers lla and llb at a certain temperature.

As described above, according to this embodiment, by directly pushing up the optical fiber lla with the bidirectional shape memory alloy 15, it is possible to configure an optical temperature sensor with fewer components.

In this embodiment, the groove provided in the main body 17 is the V-groove 12, but it may be any groove that can fix the optical fiber and align its axis, such as a groove. In addition, although the plate spring 16 was used to press the optical fiber 11b against the V-groove 12, the optical fiber ll
Needless to say, any elastic body that generates an elastic force sufficient to press b into the groove 12 may be used.

Effects of the Invention As described above, according to the present invention, one of the two optical fibers provided in the groove with their end faces facing each other is pressed into the groove with an elastic member, and at a certain temperature. Since one end of the bidirectional shape memory alloy is fixed in the range and the other end is used to push up the tip, an optical temperature sensor with fewer components can be realized, making it possible to reduce the size and cost.

[Brief Description of the Drawings] Fig. 1 is a perspective view of an optical temperature sensor according to an embodiment of the present invention, Fig. 2 a and b are front views of an optical temperature sensor according to an embodiment of the invention, and Fig. 3 is a perspective view of an optical temperature sensor according to an embodiment of the present invention. FIG. 2 is a configuration diagram of a conventional optical temperature sensor. 11a, 11b... optical fiber, 12...
...■Groove, 15...Bidirectional shape memory alloy in the form of a torsion coil spring, 16...Plate spring, 17...
...Body. /I(1)lb-m-Umi Faino\゛/2---V
Tsuru / 6 --- Nejirikoi 9 Rizame Figure 1 2 way 'Kiriji' 016- class 2\ne17--Ipponsento 2nd cause straddle

Claims (1)

[Claims] Two optical fibers are installed in the same groove with their end faces facing each other, and one end of the optical fiber is fixed and the other end is placed outside the groove within a certain temperature range. An optical temperature sensor comprising a bidirectional shape memory alloy in the shape of a torsion coil spring that is movable, and an elastic member that presses the movable optical fiber into the groove.