JPH0141988Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a temperature-sensitive valve using a shape memory alloy.

As is well known, shape memory alloys can have temperature-related shape memory effects by utilizing thermoelastic martensitic transformation. It is used in temperature-sensitive valves that open and close depending on the temperature.

The principle of the above-mentioned temperature-sensitive valve is as illustrated in Fig. 1.
A valve body d is housed in a valve body c having fluid passages a and b, and a shape memory spring e made of a shape memory alloy is housed in a compressed state between the valve body d and the valve body c. The shape memory spring e is provided with a shape memory effect such that the coil expands in a high temperature range exceeding its transformation point. Also,
A return bias spring f is used so that the shape memory spring e can be compressed in a low temperature range below the transformation point. As the bias spring f, a spring having a linear load characteristic, such as a compression coil spring, is conventionally used.

However, when the bias spring f was used, there were problems as described below. That is, as shown in FIG. 2, the bias spring f has a linear load-deflection characteristic depending on the position of the valve body d, and the larger the amount of compression, the stronger the repulsive force is generated. On the other hand, in a high temperature range above the transformation point, the shape memory spring e expands by overcoming the repulsive force of the bias spring f, and moves the valve body d, for example, in the valve opening direction. Due to the transformation, it is necessary to overcome the repulsive force of the bias spring f and be compressed to close the valve body d.

Therefore, as shown in FIG. 2, the repulsive force of the bias spring f is smaller than the repulsive force of the shape memory spring that occurs in the high temperature range, and larger than the repulsive force of the shape memory spring that occurs in the low temperature range. The specifications of the spring must be set so that it falls within the load range F. In other words, a load like a compression coil spring -
When using a bias spring with bending characteristics, the larger the spring constant, the larger the load range F needs to be. Therefore, in order to counter the required bias force, a larger and stronger shape memory spring must be used. This will require a spring f.

As an example, in a conventional temperature-sensitive valve (see Figure 1), the valve operating output is 500 g and the valve operating stroke is 20 mm.
To get one, wire diameter 1.6mm, coil center diameter 8.4
mm, effective number of turns 14, free length 70 mm, weight 5.5 g Ti−
A shape memory spring e made of Ni is required. In this case, the bias spring f is made of spring stainless steel, has a wire diameter of 1.0 mm, a coil center diameter of 10.2 mm, an effective number of turns of 25, a free length of 145 mm, and a weight of 5.3 g. need.

As can be seen from the above, conventional temperature-sensitive valves using bias springs require large and heavy shape memory springs, use large amounts of expensive shape memory alloys, resulting in high costs, and the bias springs are unnecessary. The disadvantage was that the unit also became larger because it required a number of different parts.

This idea was made based on the above circumstances,
The purpose is to provide a temperature-sensitive valve in which the shape memory spring can be made smaller and lighter, and the bias spring can be omitted, thereby making it possible to make the entire unit smaller.

In other words, the present invention, as an alternative to the conventional bias spring, has a structure that allows the valve body to move by overcoming the repulsive force of the shape memory spring in a low temperature range below the transformation point of the shape memory alloy, and also to move the valve body above the transformation point. Temperature-sensitive valves that are equipped with a weight that is heavy enough to overcome the repulsive force of the shape memory spring in the high temperature range, or apply self-weight equivalent to this weight to the valve body, and use this weight to exert a bias force. It is.

A first embodiment of the present invention will be described below with reference to FIGS. 3 to 5. In FIG. 3, reference numeral 1 denotes a valve box, in which fluid passages 2 and 3 are formed in the horizontal direction, and a valve body receiving hole 4 is formed in the vertical direction. 1a is a bottom cover. A valve body 5 is housed in the valve body housing hole 4 so as to be movable up and down. This valve body 5 has a flow passage 6 in its vertically intermediate portion, and when the valve body 5 is raised, this flow passage 6 communicates with the fluid passages 2 and 3, and when the valve body 5 is lowered, the flow passage 6 is connected to the fluid passages 2 and 3. is starting to close.

And between the valve body 5 and the valve body 1, that is, the valve body 5
For example, Ti-Ni is placed between the mutually opposing surfaces of the
A coiled shape memory spring 8 made of a shape memory alloy such as an alloy is housed in a compressed state.

This shape memory spring 8 biases the valve body 5 in the direction of pushing up the valve body 5, that is, in the valve opening direction. The shape memory spring 8 has a shape memory effect such that the coil expands in a high temperature range exceeding its transformation point. Therefore, in the low temperature range below the transformation point, martensitic transformation causes the repulsive force against compression to weaken by about 60%.

A weight 9 is provided on the valve body 5. When the shape memory spring 8 is in a low temperature range below the above-mentioned transformation point and its repulsive force against compression is weakened, the weight of the weight 9 is reduced by the weight of the valve body 5 due to gravity as shown in FIG. If the shape memory spring 8 reaches a high temperature range exceeding its transformation point and undergoes reverse martensitic transformation and returns to its shape in the direction in which the free length is extended, the valve will be defeated by the repulsive force of the shape memory spring 8. The weight is set to allow the body 5 to rise.

That is, as shown in FIG. 5, the load obtained by the valve body 5 and the weight 9 is smaller than the repulsive force of the shape memory spring that occurs in the high temperature range, and is smaller than the repulsive force of the shape memory spring that occurs in the low temperature range. It is arranged to fall within the load range F that is larger than the force. This load, ie, the bias force based on gravity, is always constant regardless of the vertical position of the valve body 5.

Since this embodiment is configured as described above, the weight 9 is held until the shape memory spring 8 reaches a predetermined temperature.
The load exerted by the valve body 5 compresses the shape memory spring 8 and closes the valve body 5. When the transformation point is exceeded, the shape memory spring 8 attempts to return to its shape in the direction of expansion due to reverse martensitic transformation, so the repulsive force increases and pushes up the valve body 5.
The flow path 6 is opened as shown in FIG. Therefore, in this state, the fluid passages 2 and 3 are in communication,
Fluid flow becomes possible.

Then, when the temperature decreases again and martensitic deformation occurs, the load from the valve body 5 and the weight 9 acts as a bias force, compressing the shape memory spring 8 and lowering the valve body 5, and the third The valve is closed as shown in the figure.

As described above, according to this embodiment, the weight of the valve body 5 and the weight 9 always acts on the valve body 5 as a constant bias force, so it is different from the conventional products (see Figs. 1 and 2). Compared to the case where a bias spring having a linear load-deflection characteristic is used, the capacity of the shape memory spring 8 can be increased by the amount that the bias force does not change. In other words, with conventional products, the greater the compression amount of the bias spring, the greater the repulsive force.
Moreover, in this state, the shape memory spring is stretched and its repulsive force weakens, so a large and strong shape memory spring is required to overcome the repulsive force of the bias spring. For example, as shown in FIG. 5, since the bias force is always constant regardless of the position of the valve body, the shape memory spring 8 corresponding to the bias force can also be small and have a thin wire diameter.

As an example, in this example, the valve actuation output is 500 g.
To obtain a valve operating stroke of 20 mm, the wire diameter is
0.6mm, coil center diameter 7.8mm, effective number of turns 11, total number of turns
13. Shape memory spring 8 with free length 45mm and weight 0.58g
The shape memory spring 8 was able to exhibit the same performance as the conventional product using a weight of 40 g, and was able to significantly reduce the size and weight of the shape memory spring 8 compared to the conventional product.

In addition, since the amount of expensive shape memory alloy used is significantly reduced compared to conventional products, it is extremely effective in reducing costs. Additionally, since there is no need to incorporate a bias spring, the volume ratio of the unit has been reduced to 30% compared to conventional products. Further, in the conventional product, the strain rate of the shape memory spring was 2.1%, but according to this embodiment, the strain rate may be 1.0%, improving durability. In the above embodiment, a weight 9 is provided separately from the valve body 5, but if the valve body 5 has a weight equivalent to the weight 9, there is no need to provide a separate weight.

FIG. 6 shows a second embodiment of the present invention, in which fluid passages 2 and 3 are vertically formed in the valve box 1, and the fluid passages are closed by a valve body 5 which also serves as a weight. 2 and 3 are opened and closed.
8 is a shape memory spring. As described in the first embodiment, the valve body 5 overcomes the repulsive force of the shape memory spring 8 and lowers the valve body in a low temperature range below the transformation point of the shape memory spring 8, and lowers the valve body above the transformation point. In the high temperature range, the valve element 5 is given enough weight to overcome the repulsive force of the shape memory spring 8 and allow the valve body 5 to rise.

According to the second embodiment configured in this way, the opening and closing of the fluid passages 2 and 3 formed in the vertical direction can be controlled, and the structure can be simplified because the valve body 5 also serves as a weight. be.

Further, in the first and second embodiments, the valve body 5 is moved up and down, but in the present invention, as shown in FIG.
It is also possible to make the weight of the valve body 5 act on the valve body 5. If the structure is such that gravity is transmitted to the valve body using the lever 10 or a link, etc., it can be applied even when the valve body 5 moves horizontally or diagonally, and the direction of movement of the valve body is not restricted. There is an advantage.

Moreover, the present invention is not limited to on-off valves, and can of course be applied to, for example, flow rate adjustment valves and directional control valves.

As mentioned above, in the present invention, the bias force is generated by a weight provided on the valve body or by a valve body having its own weight equivalent to the weight. As a result, the bias does not change, and a constant bias force can always be applied. Therefore, even a shape memory spring that is smaller and lighter than conventional springs can be adapted to the bias force, and the amount of shape memory alloy used can be significantly reduced, resulting in a significant cost reduction. Also,
Since there is no change in bias force, the distortion rate of the shape memory spring can be reduced, improving durability and providing greater freedom in design. Also, since there is no need to incorporate a bias spring, the unit can be made smaller, which has great effects.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing an example of a conventional temperature-sensitive valve, and FIG. 2 is a correlation diagram showing the relationship between the position of the valve body and the load in the conventional example. Figures 3 to 5 show an embodiment of the present invention, Figures 3 and 4 are longitudinal sectional views showing different operating states, and Figure 5 shows the relationship between the position of the valve body and the load. Load-deflection diagram,
FIGS. 6 and 7 are longitudinal sectional views showing other embodiments of the present invention, respectively. 1... Valve box, 2, 3... Fluid passage, 5... Valve body, 8... Shape memory spring, 9... Weight.

Claims (1)

[Scope of utility model registration request] A valve body provided with a fluid passage accommodates a valve body that is slidable in the direction of opening and closing the fluid passage, and a valve body that is slidable in the direction of opening or closing the fluid passage is housed between the valve body and the valve body. A shape memory spring made of a shape memory alloy that biases in one direction is housed, and the valve body further includes:
In the low temperature range below the transformation point of the shape memory alloy mentioned above, the valve body is moved by overcoming the repulsive force of the shape memory spring, and in the high temperature range above the transformation point, the valve body is moved by weight that overcomes the repulsion force of the shape memory spring. 1. A temperature-sensitive valve characterized in that a weight is provided, or a self-weight equivalent to the weight is applied to a valve body.