JPH0247597B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermally responsive device using a shape memory spring whose operating temperature can be varied.

The operating temperature of shape memory alloys is uniquely determined by the phase transformation temperature unique to the material. For this reason, conventional thermal response devices using shape memory alloys are convenient for operating at a constant temperature, but have the disadvantage that the operating temperature cannot be freely adjusted.

For example, FIGS. 1A and 1B show an example of a conventional thermal response device, in which a constant load is applied by a weight c to a shape memory spring b housed in a case a. The shape memory spring b is a second
As illustrated in the figure, the relationship between load and deflection changes between low temperature T ₁ and high temperature T ₂ , so if the load W is constant, the deflection by Δδ will change between low temperature T ₁ and high temperature T ₂ . Make a difference. Therefore, at low temperatures below T ₁ , the first
As shown in Figure A, the weight c is in a lowered state, and when the temperature _T2 is higher than the operation start temperature _T1 , the weight c is pushed up by Δδ as shown in Figure 1B.

As is clear from the above explanation, in the conventional thermal response device, the operation start temperature _T1 is constant, and in order to change this operation temperature, it is necessary to change the size of the shape memory spring b,
It was necessary to change the specifications such as the shape, the alloy composition, or the heat treatment temperature, and in any case, it was not possible to arbitrarily change the operating temperature with a single thermal response device.

Therefore, conventional heat-responsive devices cannot be used in various types of equipment that require a temperature control function, such as air conditioners, refrigerators, water heaters, thermostats, and the like. Moreover, in order to satisfy the required operating conditions (operating temperature, load, etc.), the phase transformation temperature of the shape memory alloy material used is uniquely determined, and there is no freedom in material selection. .

The present invention was made based on the above circumstances, and its purpose is to be able to change the operating temperature arbitrarily and to be used in a wide range of applications such as a temperature control device, and to have shape memory when obtaining a predetermined operating temperature. It is an object of the present invention to provide a thermally responsive device using a shape memory spring that can expand the degree of freedom in selecting alloy materials.

That is, the present invention provides a shape memory spring that is made of a shape memory alloy and whose relationship between load and deflection changes depending on temperature, a load applying body that applies a constant load to the shape memory spring, and a load applying body that regulates the deflection of the shape memory spring. This is a thermally responsive device using a shape memory spring, characterized by comprising a stopper and a deflection adjustment mechanism that arbitrarily changes the initial deflection of the shape memory spring.

An embodiment of the present invention will be described below with reference to FIGS. 3 to 5. In FIG. 3, numeral 1 indicates a shape memory spring. This shape memory spring 1
is made of a shape memory alloy such as Ti-Ni alloy, for example, the wire diameter is 0.75 mm and the average coil diameter is 7.75 mm.
mm, and the effective number of turns is 6.25. In addition, the phase transformation temperature is, for example, A _s = 41℃, A _f = 50℃, M _s = 39℃.
℃, M _f =34℃. 200 for this shape memory spring 1
When the temperature is varied in the range of 35 to 60°C while a constant load of 1.5 g is applied, the temperature-deflection diagram shown in Figure 4 is obtained.

In other words, when the temperature of the shape memory alloy is increased, the reverse transformation start temperature A _s of martensite changes to the reverse transformation end temperature A _f
The elastic modulus increases continuously until the temperature decreases, and conversely, when the temperature decreases, the elastic modulus decreases continuously from the martensitic transformation start temperature M _s to the martensitic transformation end temperature M _f . Therefore, if the load is constant (200 g), the deflection There is a characteristic that the larger the value, the lower the operating temperature. The present invention utilizes the fact that the spring constant of the shape memory spring changes continuously depending on the temperature.

A weight 2, which is an example of a load applying body, is mounted on the shape memory spring 1 to apply a constant load (for example, 200 gf), and a stopper 3 is mounted to prevent the weight 2 from falling below a predetermined position. is provided. That is, this stopper 3 has a function of regulating the initial deflection amount of the shape memory spring 1.

A cam 4 as an example of a deflection adjustment mechanism is provided below the shape memory spring 1 in the drawing. This cam 4 is rotatable about a shaft 4a, and its rotational position can be freely changed by an operator such as a handle (not shown). Therefore, by changing the rotational position of the cam 4, the initial deflection of the shape memory spring 1, that is, the amount of deflection when the weight 2 is in contact with the stopper 3 can be changed.

The shape of the cam is such that the distance l from the cam center to the cam surface changes continuously depending on the rotation angle of the cam. Specifically, in the temperature-deflection diagram shown in Figure 4, each temperature
It is designed so that the distance l from the cam center 0 to the cam surface changes non-linearly at the same rate as the amount of change in deflection from a to g corresponding to 58°C. That is, by creating a cam shape that matches the deflection change shown in FIG. 4, the operating temperature setting can be converted to a constant rotation angle of the cam 4.

In this embodiment configured as described above, the cam 4 is configured such that the shape memory spring 1 is pushed by the portion a of the cam 4, for example.
When rotated, the shape memory spring 1 has an initial deflection (compression amount) of about 11 mm relative to its free height. Therefore, as is clear from Figure 4, when the temperature is raised, if the temperature is below 40°C, it will not produce enough output to push up weight 2, but if the temperature exceeds 40°C, it will deflect against the weight of weight 2. The shape memory spring 1 extends in the direction of becoming smaller than 11 mm, thereby pushing the weight 2 up and away from the stopper 3. In other words, the operating start temperature in this case is 40°C. As the temperature rises, the deflection of the shape memory spring 1 becomes smaller and the amount of rise of the weight 2 becomes larger.

On the other hand, when the cam 4 is rotated so that the shape-memory spring 1 is pushed by the g section of the cam 4, the initial deflection of the shape-memory spring 1 becomes small, contrary to the above-mentioned section a. In other words, the initial deflection (compression amount) is approximately 6 mm relative to the free height. Therefore, as shown in Figure 4, when the initial deflection is 6 mm, the weight is 2 at around 58°C.
produces an output that pushes up. In other words, the starting temperature increases to 58°C.

Similarly, if the shape memory spring 1 is pressed with any part b to f of the cam 4, the activation start temperature will be 43°C and 46°C, respectively, depending on the initial deflection.
℃, 49℃, 52℃, 55℃. In other words, the operation start temperature can be arbitrarily adjusted within the range of 40 to 58°C depending on the rotational position of the cam 4. Moreover, according to the cam 4, since the operating start temperature can be changed at a constant rate at the same rotation angle as described above, the scale of the handle for rotating the cam 4 and the operating temperature are in direct proportion to each other. and can be made easy to use. In this example, the operating temperature is 1 for a cam rotation angle of 10°.
℃ changes. However, it is not always necessary to adopt such a cam shape, and in short, shape memory spring 1
The desired purpose can be achieved with a cam that can change the initial deflection of the cam.

As described above, according to this embodiment, by changing the initial deflection while a constant load is applied, the operation start temperature during temperature rise can be arbitrarily and continuously changed. Therefore, air conditioners, refrigerators,
It can be widely used as a temperature control device for water heaters, thermostats, etc. Furthermore, since the operating stroke and output energy can be increased compared to conventional bimetallic thermal response devices, the device can be used not only for a simple temperature control function but also as an actuator. Therefore, it can be used as a flow rate adjustment valve for gas or liquid according to temperature changes, or as a flow path switching valve.

Further, according to this embodiment, for example, the operation start temperature can be changed to
If you want to set the temperature to 50℃, you only need to select the phase transformation temperature A _s of the shape memory spring material in the range of 50 to 70℃. There is an advantage that there is a wide degree of freedom in selecting alloy materials.

In the above embodiment, the cam 4 is used to change the initial deflection, but the initial deflection may be changed by a deflection adjusting mechanism other than the cam. Further, in the above embodiment, the operating temperature is changed continuously, but the operating temperature may be changed stepwise, for example, by changing the initial deflection in steps.

In addition, although the above embodiment describes the case where the operation start temperature is changed when the temperature rises, the operation end temperature when the temperature is lowered is also determined based on the temperature-deflection curve when the temperature is lowered as shown in FIG. Just set the deflection.

Furthermore, a spring may be used instead of a weight as the load applying body, and the spring force may be adjusted, as long as a predetermined initial load can be applied. Furthermore, the magnitude of the load is not limited to the embodiments, and can be modified in various ways without departing from the gist of the present invention. Furthermore, the present invention is not limited to coil springs, but may also employ shape memory springs of any shape, such as leaf springs, torsion springs, and others.

As explained above, according to the present invention, the initial deflection can be changed in various ways by the deflection adjustment mechanism under a constant load, and the operating temperature can be changed arbitrarily. .
Therefore, it can be used in devices that require a temperature control function or devices that need to operate at various temperatures, greatly expanding the range of applications. Furthermore, even if there is no need to change the operating temperature, the phase transformation temperature of the shape memory alloy material can be selected within a wide range to obtain the required predetermined operating temperature, increasing the degree of freedom in material selection. It has a big effect on spreading.

[Brief explanation of the drawing]

Figures 1A and 1B are schematic diagrams showing conventional thermal response devices in different operating states, Figure 2 is a load-deflection diagram of a shape memory spring in the same thermal response device, and Figure 3 is a diagram of the present invention. FIG. 4 is a diagram showing a temperature-deflection diagram of a shape memory spring in the embodiment, and FIG. 5 is a diagram showing a cam shape in the embodiment. 1... Shape memory spring, 2... Weight (load applying body), 3... Stopper, 4... Cam (deflection adjustment mechanism).

Claims (1)

[Claims] 1. A shape memory spring that is made of a shape memory alloy and whose relationship between load and deflection changes depending on temperature; a load applying body that applies a constant load to the shape memory spring; a stopper that regulates the deflection of the shape memory spring; A thermally responsive device using a shape memory spring, characterized by comprising a deflection adjustment mechanism that arbitrarily changes the initial deflection of the shape memory spring.