JPH0319431B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature-responsive drain valve that uses a shape memory alloy as a temperature-responsive element.

An example of a temperature-sensitive valve using a shape memory alloy as a temperature-sensitive element is disclosed in Japanese Patent Application Laid-open No. 150680/1983.

As shown in FIG. 1, this conventional temperature-responsive valve has a valve body 4 which opens and closes a valve port 3 of a valve seat member 2 supported in a main body 1 so as to be movable up and down through a support wall 5.
A bias coil spring 7 for biasing the valve body 4 in the opening direction is installed between the flange 6 fixed to the upper end of the valve shaft 4a of the valve body 4 and the upper surface of the support wall 5. A coil spring 8 made of a shape memory alloy is installed between the lower surface of the valve body 4 and the valve head 4b of the valve body 4 to extend and bias the valve body 4 in the closing direction.

In actual operation, when the main body 1 is directly connected with the fluid passages in communication with each other and the inside of the main body 1 is maintained at a high temperature by the passing fluid, as shown in FIG. When the shape memory alloy coil spring 8 overcomes the spring pressure of the bias coil spring 7 and expands, the valve body 4 is lowered,
When the valve head 4b automatically closes the valve port 3 and, conversely, the inside of the main body 1 becomes low temperature, the shape memory alloy spring 8 contracts, and the bias coil spring 7 Since the spring pressure overcomes this, the valve body 4 rises and automatically opens the valve port 3.

However, in such a temperature-responsive valve, the temperature inside the main body 1, which is maintained at a high temperature by the passing fluid, is not always constant, and tends to reach a high temperature of, for example, 100° C. or higher due to internal pressure and the like.

For this reason, in the above-mentioned conventional temperature-responsive valve, the coil spring 8 made of shape memory alloy is expanded and is exposed to a high temperature atmosphere of 100°C or more while the valve head 4b closes the valve port 3. Due to its structure, the expansion force of the shape memory alloy coil spring 8 is restricted between the support wall 5 and the valve head 4b, so as a characteristic of the shape memory alloy, it tends to expand further depending on the temperature. Even if it were, it would not be able to elongate and would be subject to continuous restraint heating.

Therefore, when such a restrained heating state continues, the ability of the shape memory alloy coil spring 8 itself deteriorates,
Naturally, this will cause the shape memory alloy coil spring 8 to have a reduced elasticity, and even if it receives the auxiliary action of the bias coil spring 7, the valve port 3 will not open or close normally. will no longer be guaranteed.

Considering this point, if the shape memory alloy coil spring 8 is exposed to a high temperature atmosphere for a long time, it is possible to effectively prevent the occurrence of fatigue by promoting the elongation ability of the coil spring 8. It will be possible.

Incidentally, the conventional temperature-responsive valve described above is simply connected directly to a fluid passageway and is configured to allow or block the passage of fluid within the passageway. Needless to say, similar problems arise with drain valves intended for automatic drainage.

Accordingly, the present invention is for temperature-sensitive operation of a shape memory alloy, and when a shape memory alloy coil spring is expanded, a valve body is raised to close a valve port, and conversely, a shape memory alloy coil spring is By contracting,
Assuming that the temperature-responsive drain valve has a configuration in which the valve body is lowered to open the valve port, a concave drain reservoir is formed at the bottom of the main body that is externally connected to the steam passage, and a valve port is installed in the concave drain reservoir. A valve seat member defining a drain reservoir is provided, and a valve body having a valve shaft is supported at the valve opening of the valve seat member so as to be movable up and down, and the valve defined in the drain reservoir portion is moved up and down by the up and down movement of the valve body. While the mouth is configured to open and close, a movable ring is loosely fitted in the middle of the valve shaft of the valve body so as to be movable up and down, and a shape memory alloy coil spring is installed between the lower surface of the movable ring and the valve seat member, and the valve body is movable. By adopting a structure in which an absorbing coil spring is installed between the upper surface of the ring and the fixed flange at the upper end of the valve stem,
It is an object of the present invention to provide a novel drain valve that can effectively prevent the shape memory alloy coil spring from becoming sagging by releasing the shape memory alloy coil spring from the restrained heating state in a high temperature atmosphere.

Hereinafter, the present invention will be described in detail based on an illustrated embodiment. As shown in FIG. A valve body having a concave drain reservoir formed at the bottom thereof, a valve seat member 2 defining a valve port 3 in the concave drain reservoir, and a valve shaft 4a at the valve port 3 of the valve seat member 2. 4 is supported so as to be movable up and down, and the valve opening 3 defined in the drain reservoir section is opened and closed by the up and down movement of the valve body 4.

In this embodiment, a movable ring 10 is loosely fitted in the middle of the valve shaft 4a of the valve body 4 so as to be movable up and down, and the valve seat that defines the lower surface of the movable ring 10 and the valve port 3 is provided. A shape memory alloy coil spring 8 is installed between the members 2, which expands when the temperature is high and contracts when the temperature is low. An absorption coil spring 11 that efficiently absorbs the expansion force of the alloy coil spring 8 is attached, and the absorption coil spring 11 is combined with the shape memory alloy coil spring 8 with the movable ring 10 that can move up and down interposed therebetween. By this, shape memory alloy coil spring 8 at high temperature
The structure is such that it can be expanded even from a restrained heating state.

Therefore, even with a temperature-responsive drain valve having such a configuration, if drain accumulates in the concave reservoir at the bottom of the main body 1 connected to the steam passage from the outside and the temperature inside the main body 1 decreases, the temperature inside the main body 1 will decrease. As shown in A, the shape memory alloy coil spring 8 contracts and lowers the valve body 4, so that the valve port 3 automatically opens and the drain is reliably drained out of the main body 1. Conversely, when the inside of the main body 1 becomes high temperature again due to steam, the shape memory alloy coil spring 8 expands and lifts the valve body 4, so that the valve head 4b closes the valve opening. 3 will be automatically closed.

However, in such a closed state, if the inside of the main body 1 is exposed to a high temperature atmosphere of 100° C. or higher due to internal pressure, etc., as shown in FIG. Alloy coil spring 8
Its own elongation force is effectively absorbed and it becomes possible to elongate further. That is, as shown in the figure, if the length of the absorbing coil spring 11 before absorption is H, then in a high temperature atmosphere, the shape memory alloy coil spring 8 contracts by the amount α absorbed by the elongation, and the absorbing coil spring 11 contracts. Since the length dimension after absorption becomes H-α, this makes it possible for the shape memory alloy coil spring 8 to expand.

As a result, even if the shape memory alloy coil spring 8 is used for a long time in a high-temperature atmosphere, the shape memory alloy coil spring 8 will not be heated while being restrained as in the conventional case, so there is no fear of damage.

To explain this point based on the results of an experiment comparing a conventional temperature-responsive valve that does not have the absorbing coil spring 11 and this temperature-responsive drain valve, it is assumed that the valve closing force, that is, the valve opening 3 caused by the valve body 4 Assuming that the closing force is 2 kg, in the case of a conventional response valve that does not have the absorbing coil spring 11, the valve closing force increases rapidly as the temperature increases, as shown by line A in Figure 4. However, in the case of the present drain valve having the absorption coil spring 11, as shown by line B in the figure, it has been found that the valve closing force remains approximately constant even when the temperature rises from around 100°C. . This means that the absorbing coil spring 11 efficiently absorbs the fatigue phenomenon of the shape memory alloy coil spring 8.

Further, the temperature-responsive drain valve shown in FIG. 5 shows another embodiment of the present invention, and the other embodiment is based on the structure of the above-described embodiment, and further includes a fixed flange of the valve shaft 4a. A bias coil spring 12 is installed between the upper surface of the section 6 and the corresponding inner wall surface of the main body 1. In particular, in this other embodiment, the presence of the bias coil spring 12 makes it possible to open and close the valve more reliably than described above. Other operations are similar to those of the previous embodiment.

As described above, by employing the above-mentioned configuration, the present invention can prevent the shape memory alloy coil spring from being exposed even if the main body is exposed to a high temperature atmosphere and the shape memory alloy coil spring is exposed to the atmosphere for a long time. Since the spring can be expanded by the absorption action of the absorption coil spring, it is possible to effectively prevent the occurrence of fatigue.

Furthermore, in the present invention, a concave drain reservoir is formed at the bottom of the main body connected to the steam passage from the outside, and the concave reservoir is configured to collect the drain, so that the drain can be collected reliably. Since it is possible to introduce water into the main body and automatically drain water as required, in conjunction with the above-mentioned effects, it is now possible to provide for the first time a temperature-responsive drain valve that guarantees reliable opening and closing operations.

[Brief explanation of the drawing]

Figure 1A is a sectional view showing a conventional temperature-responsive valve using a shape memory alloy coil spring as a temperature-sensitive element in a closed state, Figure 1B is a sectional view showing the same valve in an open state, The figure is a sectional view showing the temperature-responsive drain valve in an open state according to an embodiment of the present invention, and FIG.
B and C are main part explanatory diagrams showing the relationship between the shape memory alloy coil spring and the absorption coil spring in the valve open, valve closed, and closed valve states under high temperature atmosphere, and Figure 4 shows the conventional temperature-responsive valve and the actual temperature. FIG. 5 is a diagram showing the relationship between temperature and valve closing force of a responsive drain valve, and is a sectional view showing another embodiment of the temperature responsive drain valve according to the present invention in a closed state. 1...Main body, 2...Valve seat member, 3...Valve port, 4
... Valve body, 4a ... Valve shaft, 6 ... Fixed flange, 8 ...
... Shape memory alloy coil spring, 10... Moving ring, 11... Absorption coil spring.

Claims (1)

[Claims] 1. For temperature-sensitive operation of shape memory alloy, the shape memory alloy coil spring expands to raise the valve body and close the valve port, and conversely, the shape memory alloy coil spring expands to close the valve body. A temperature-responsive drain valve configured to lower the valve body and open the valve port when contracted, which forms a concave drain reservoir at the bottom of the main body connected to the steam passage from the outside, and the concave drain A valve seat member defining a valve port is provided in the reservoir portion, and a valve body having a valve shaft is supported on the valve port of the valve seat member so as to be movable up and down. The valve opening is configured to open and close, and a movable ring is loosely fitted in the middle of the valve shaft of the valve body so as to be movable up and down.
A temperature-responsive valve characterized in that a coil spring made of a shape memory alloy is installed between the lower surface of the moving ring and the valve seat member, and an absorbing coil spring is installed between the upper surface of the moving ring and the fixed flange at the upper end of the valve shaft. drain valve.