JPH049960B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a steam trap that automatically drains condensate by using a shape memory alloy spring as a temperature-sensitive element.

``Prior art'' The applicant filed a practical application regarding this type of steam trap in 1983.
-Already provided with No. 103870.

As shown in FIG. 4, such a conventional trap has a hollow trap body 2 which communicates with a steam flow pipe 1 at the upper part, and a drain valve 5 formed in the lower part of the trap body 2 through a support 4. The valve shaft 5b of the drain valve 5 is supported so as to be movable up and down, and the lower discharge port 3 is opened and closed by the drain valve 5 having a valve head 5a on the lower side. A flange 6 is provided, and a coiled shape memory alloy spring 7 is installed between the lower surface of the flange 6 and the upper surface of the support 4 to normally bias the drain valve 5 in the closing direction, that is, in the upward direction. A bias spring 8 in the shape of a conical coil is installed between the upper surface and the corresponding inner wall surface of the upper part of the main body 2, which always biases the drain valve 5 in the open direction, that is, in the downward direction.

In actual operation, when a part of the steam in the steam distribution pipe 1 cools down and becomes drain, the drain is immediately caused to flow down into the lower part of the hollow body 2. Then, the shape memory alloy spring 7 directly senses the temperature of the downstream drain and contracts, and the spring pressure of the bias spring 8 overcomes the spring pressure of the shape memory alloy spring 7.
As shown, the drain valve 5 descends under the guidance of the support 4, automatically opens the lower discharge port 3, and naturally drains the drain from the discharge port 3 to the outside through the through holes 4a of the support 4.

After complete drainage, when the inside of the main body 2 becomes high temperature again due to steam, the shape memory alloy spring 7 senses the high temperature and expands, overcoming the spring pressure of the bias spring 8, as shown in Figure A. The drain valve 5 rises and automatically closes the discharge port 3 with its own valve head 5a.

``Problems to be Solved by the Invention'' However, in the case of such conventional traps, no matter what state the interior of the trap body 2 is in, as described above, it is always in communication with the steam flow pipe 1. The shape memory alloy spring 7 attached to the main body 2 has the disadvantage of being directly exposed to high temperature steam for a long period of time.

That is, due to its characteristics, if the shape memory alloy spring 7 is exposed to a high-temperature atmosphere for a long time, its durability and reliability will drop significantly. In the conventional sensing structure, the shape memory alloy spring 7 is naturally exposed to high-temperature steam, so it is likely to become stiff.
This poses a major problem in that it lacks operational reliability.

In addition, as a conventional technique, there are also steam traps shown in, for example, Japanese Utility Model Application Publication No. 59-141295 and Japanese Utility Model Application Publication No. 58-9595, etc., but these traps are The shape memory alloy spring can be attached directly to the trap, or similarly to the above, the shape memory alloy spring can be attached inside the trap body that communicates with the steam flow pipe. Shape-memory alloy springs have problems with wear and tear as they are exposed to water for long periods of time.

"Means for Solving the Problems" The present invention has been developed to effectively solve the problems of the conventional traps described above, and includes a discharge port of the trap body that communicates with the flow pipe in the upper part. is opened and closed by a drain valve that is supported in the trap body so that it can be raised and lowered, and the drain valve is equipped with a shape memory alloy spring and a bias spring, respectively, so that the shape memory alloy spring can be operated in response to temperature changes. Assuming that the steam trap is configured to automatically open and close the discharge port by raising and lowering the drain valve, a drain reservoir is formed in the upper part of the trap body communicating with the steam distribution pipe, and the drain reservoir is A drain outlet is formed directly below, and the outlet is opened and closed by a drain valve having a valve head on the upper side, while the drain flows down from the outlet to the bottom wall of the lower part of the trap body away from the steam communication pipe. A perforated hole is formed for draining the drain to the outside, and a shape memory alloy spring is installed between the lower bottom wall having the perforated hole in the trap book and the lower end of the valve shaft of the drain valve, and the shape memory alloy spring is connected to the shape memory alloy spring. We adopted a configuration that indirectly senses temperature changes.

``Operation'' According to the present invention, if the discharge port formed directly below the drain chamber in the upper part of the trap main body that communicates with the steam distribution pipe is closed with a drain valve having a valve head on the upper side, high-temperature steam can be discharged. The shape memory alloy spring attached to the lower end of the valve stem of the drain valve is completely cut off, and the shape memory alloy spring only indirectly senses the temperature change in the drain reservoir chamber by transmitting the temperature change to the main body. This eliminates direct exposure to high-temperature steam, prevents sagging, and ensures operational reliability.

"Example" The present invention will be described in detail below based on an illustrative example.

The trap according to the first embodiment of the present invention, as shown in FIG. A discharge port 13 that is opened and closed by a drain valve 15 is formed directly below the chamber 19, and a plurality of through holes 1 are formed approximately in the center of the main body 12.
A support wall 14 having a valve head 15a is provided on the support wall 14, and a valve stem 1 of a drain valve 15 having a valve head 15a on the upper side is provided on the support wall 14.
5b is supported so that it can be raised and lowered, and as the drain valve 5b is raised and lowered, the discharge port 13 located on the upper side is connected to the valve head 15a of the drain valve 15.
It is configured to open and close with.

In addition, a perforation 20 is formed in the bottom wall of the trap body 12 at the lower part remote from the steam distribution pipe 1, for draining the drain flowing down from the outlet 13 through the through holes 14a of the support wall 14 to the outside. A flange portion 16a is provided at the lower end of the valve shaft 15b of the valve 15, and the flange portion 1
A coiled shape memory alloy spring 17 is attached to the lower surface of the drain valve 6a and the inner surface of the corresponding inner wall of the lower bottom wall of the main body 12 having the perforated hole 20, which normally biases the drain valve 15 in the closing direction, that is, in the upward direction. Therefore, the shape memory alloy spring 7 is installed separated from the drain reservoir chamber 19.

Furthermore, the valve shaft 1 located above the support wall 14
5b is provided with another flange 16b at an appropriate position, and the flange 16
A conical coil-shaped bias spring 18 is installed between the upper surface b and the corresponding inner wall surface of the upper part of the main body 12 to always bias the drain valve 15 in the open direction, that is, in the downward direction.

Therefore, in the steam trap of the first embodiment, when the upper discharge port 13 is closed by the upper valve head 15a of the drain valve 15 as shown in FIG. Since the closed state completely cuts off the high temperature steam in the steam flow pipe 1 and the shape memory alloy spring 17, the shape memory alloy spring 17 is never directly exposed to high temperature steam.

Note that the steam temperature is transmitted through the wall of the main body 12.
The temperature of the atmosphere surrounding the shape memory alloy spring 17 at the bottom of the main body 12 becomes high.However, since the temperature of the steam inevitably becomes low during the transmission process, the temperature of the atmosphere also naturally decreases to the temperature of the steam. It will be perceived as a lower temperature.

In addition, when a part of the steam in the steam distribution pipe 1 cools down and becomes drain when the discharge port 13 is closed, the drain does not immediately flow into the main body 12 but is temporarily stored in the reservoir chamber 19 of the main body 12. The temperature of the drain is also transmitted along the wall of the main body 12 toward the lower part of the main body 12 while gradually decreasing in temperature.
The temperature of the atmosphere surrounding the shape memory alloy spring 17 in the lower part of the chamber 19 is set to be at least considerably lower than the drain temperature in the reservoir chamber 19.

Then, the atmospheric temperature is changed to the shape memory alloy spring 17.
is sensed and contracts, so the spring pressure of the bias spring 18 overcomes the spring pressure of the shape memory alloy spring 17, and the drain valve 15 closes against the support wall 14 as shown in FIG.
The upper discharge port 13 is automatically opened, and the drain is naturally drained from the reservoir chamber 19 to the outside through the discharge port 13, the through hole 14a, and the perforation 20.

After complete drainage, the atmosphere surrounding the shape memory alloy spring 17 becomes high due to the steam flowing directly from the outlet 13 of the main body 12 and the heat transmitted through the wall of the main body 12, and this temperature causes the shape memory alloy spring 1 to
7 expands and overcomes the spring pressure of the bias spring 18, the drain valve 15 rises as shown in FIG. As a result, the shape memory alloy spring 17 is again isolated from the high temperature steam.

That is, in this trap, the steam/drain and the shape memory alloy spring 17, which is a temperature-sensitive element, are separated and each temperature is indirectly sensed as the ambient temperature. Not only is it possible to keep the shape memory alloy spring 17 in an extended state without directly exposing it to high-temperature steam, but also the martensitic transformation temperature can be indirectly sensed and the condensate can be drained as is. There will be absolutely no negative effects caused by this.

Therefore, based on the following, when comparing the relationship between deflection and load at each temperature of the shape memory alloy spring 17 of this trap and the shape memory alloy spring 7 of the conventional trap shown in FIG. 4, the relationship between deflection and load at each temperature is shown in FIG. As shown, the shape memory alloy spring 17 of this trap that indirectly senses temperature changes is in the range from A to B, i.e.
For example, it only expands and contracts between 50℃ and 100℃,
The shape memory alloy spring 7 of the conventional trap, which is directly exposed to high-temperature steam, is further restrained and heated by the high-temperature steam in the range from B to C, that is, between 100°C and 120°C, and tries to expand in its valve open state. Therefore, this makes the shape memory alloy spring 7 more likely to wear out.

Therefore, when both shape memory alloy springs are used repeatedly, as is clear from line D shown in FIG.
In this trap, the stress value remains approximately constant even if the number of repeated uses increases, but in the case of conventional traps, as the number of repeated uses increases, , the stress value gradually decreases.

As a result, it is clear that the reliability of operation is sufficiently ensured in the case of the trap of the present invention, whereas in the case of the conventional trap, on the contrary, the reliability of operation is greatly reduced.

Moreover, if we show the relationship between the change in the ambient temperature surrounding the shape memory alloy spring 17 and time, as shown in Figure 2, temperature changes of 100°C and 50°C can be obtained in a short time, and many opening and closing operations can be performed in a short time. It will be repeated. This means that the discharge port 13 can be opened and closed quickly, which means that the draining efficiency of the drain can be greatly improved, and the time that the drain is exposed to high-temperature steam during draining is also extremely short. It turns out that there is no adverse effect of temperature.

Furthermore, since the martensitic transformation temperature of the normally shaped alloy spring 17 is set at 50 to 60°C, in the past it was impossible to drain the drain unless the drain temperature also reached that temperature. Even if the drain temperature is 50 to 60° C. or higher in the trap, the temperature is low during the transmission process of the main body 12, so that the operation of the shape memory alloy spring 17 is not affected from this point of view as well.

The steam trap according to the second embodiment is a modification of the first embodiment, and the difference is that, as shown in FIG. It is attached between the lower surfaces and the separate flange portion 16b is omitted, and all other configurations and functions are the same as in the first embodiment.

"Effects of the Invention" As described above, the present invention does not allow the shape memory alloy spring to directly sense temperature changes, as in the past, but indirectly senses the temperature changes as the ambient temperature transmitted from the trap body. Because of this feature, there is no need to worry about the shape memory alloy spring being directly exposed to high-temperature steam.

Therefore, in the steam trap of the present invention, the shape memory alloy spring is effectively prevented from becoming sagging, and the operational reliability of the steam trap is sufficiently ensured.

[Brief explanation of drawings]

FIG. 1A is a sectional view showing a steam trap according to the first embodiment of the present invention with the exhaust port closed, FIG. 1B is a sectional view showing the steam trap with the exhaust port open, and FIG. An explanatory diagram showing the opening/closing state of the outlet in relation to changes in the ambient temperature surrounding the shape memory alloy spring and time. FIG. 3 is a cross section showing the steam trap according to the second embodiment of the present invention with the outlet closed. Figure 4A is a cross-sectional view of a conventional steam trap with the outlet closed, Figure B is a cross-sectional view with the outlet open, and Figure 5 is a cross-sectional view of the conventional steam trap with the outlet open. A diagram showing the relationship between deflection and load at each temperature in a shape memory alloy spring, and FIG. 6 is a diagram showing the relationship between the number of repeated uses and stress. 1... Steam distribution pipe, 12... Trap body, 1
3...Discharge port, 15...Drain valve, 15a...Valve head, 15b...Valve shaft, 16a, 16b...Brim part,
17...Shape memory alloy spring, 18...Bias spring, 19...Drain reservoir, 20...Drilling hole.

Claims (1)

[Scope of Claims] 1. The exhaust port of the trap body communicating with the steam distribution pipe at the upper part is opened and closed by a drain valve supported in the trap body so as to be movable up and down, and
A steam trap having a structure in which a shape memory alloy spring and a bias spring are respectively attached to the drain valve, and the drain valve is raised and lowered to automatically open and close the discharge port for temperature-sensitive operation of the shape memory alloy spring due to temperature changes, A drain reservoir is formed in the upper part of the trap main body communicating with the steam distribution pipe, and a drain outlet is formed directly below the drain reservoir chamber, and the outlet is connected to a drain valve having a valve head on the upper side. The trap body is configured to open and close, and at the same time, a perforation is formed in the lower bottom wall of the trap body away from the steam communication pipe for discharging drain flowing down from the discharge port to the outside, and a lower bottom wall of the trap body having the perforation is formed. A steam trap characterized in that a shape memory alloy spring is installed between the lower end of the valve shaft of the drain valve, and the shape memory alloy spring is configured to indirectly sense temperature changes.