CN1004830B

CN1004830B - drain valve

Info

Publication number: CN1004830B
Application number: CN87107580.6A
Authority: CN
Inventors: 张立夫
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-10-21
Filing date: 1987-10-21
Publication date: 1989-07-19
Also published as: CN87107580A

Abstract

The invention provides a thermal expansion type steam trap, which is suitable for working pressure ≤ 25Kgf/cm ² . The characteristic of this valve is to control and achieve the purpose of blocking steam and draining water by using the volume expansion produced by the combination of metal bellows and elastic material when the temperature changes. The valve also has adjustability and continuous drainage capability.

Description

Drain valve

The invention relates to a drain valve, in particular to a drain valve with a thermosensitive element which is cast into a whole by adopting rubber and a corrugated pipe or is only made of rubber materials.

The present invention is a continuation of my invention application filed on 16.11.1985 with application number 85108332.

A bellows trap for steam heating is disclosed in US 3876139. The heat sensitive element-corrugated pipe only uses the axial displacement deltax of the elastic shell in the work, and when the elastic shell with one fixed end is axially extended under the heating condition, although the moving direction is basically the X axial direction, the elastic shell has poor and unstable rigidity and poor capability of bearing the action in the transverse direction (Y direction). When the moving end touches an obstacle or a target object (valve seat), the corrugated pipe shell is easy to warp, and particularly the middle part of the corrugated pipe shell is arched outwards, so that the normal matching position between the valve clack and the valve seat cannot be ensured, and the result is that steam leakage is caused or stress concentration of a certain part of the elastic shell is cracked. This is especially true for long bellows (with larger wave numbers) in large bore traps. Because the large-caliber trap needs to have a larger displacement value Delta X and bear larger total steam pressure. For example, 10-15 waves are required for the general caliber Dg32 to obtain a sufficient flow cross section of the water outlet, however, the increase of the wave number causes the increase of the steam leakage rate and the cracking of the corrugated pipe. In addition, bellows-like traps have a weak point. When the internal liquid is vaporized by heating, the internal pressure increases suddenly, and its value tends to approach the allowable stress of its elastic shell. In addition to the external pressure on the flexible housing after expansion, the housing is easily broken because the bellows housing is both a heat sensitive element and a force-receiving element, which serves a dual function. From mechanical analysis, the inner surface of the shell is uniformly applied with outward force of the expanding gas, and the outer part of the shell has concentrated force at two ends (after the valve clack touches the valve seat). To place the shell material in a multi-stress state, the shell will crack once the material's allowable value is exceeded.

The invention aims to provide a novel thermosensitive sensing device, which improves the sensitivity and reliability of steam resistance and drainage of a valve by increasing the stroke of a valve clack element.

Another object of the present invention is to provide a combined thermal sensing device for corrugated pipes, so as to improve the stress state of the corrugated pipe elements in the prior art. To improve the durability of the element.

It is a further object of the present invention to provide a trap of valve construction that provides good opening and closing performance and prevents steam leakage.

The above object of the present invention is achieved by the following means. In a trap valve assembly consisting essentially of a housing, a thermally sensitive sensor element and a setting device therefor. The thermosensitive expansion body with a combined structure is formed by casting a rubber material and a corrugated pipe filled with an easily-evaporated liquid into a whole. It is limited in a rigid casing with one open end, and the opening size of the valve clacks is controlled by the expansion amount of the body. For a small-bore trap with a small amount of displacement of the valve flap. The expansion body consists of only one material of rubber. In addition, the whole heat-sensitive sensing element and the valve clack are in the valve cavity, and the relative setting device and the valve seat are in a floating type.

The advantage of the invention is that the principle of bulk expansion replaces the single linear expansion principle in the past. The invention has the advantages of obtaining larger thermal static force action stroke with smaller components, thereby improving the thermal sensitivity and the steam-resistant and water-draining capacity, and casting the corrugated pipe in a rubber body which is limited in a rigid shell. The pressure-sensitive sensing element and the valve clack are floating in the valve cavity. The influence of the action of thermal expansion and contraction on the valve clack is avoided, and the valve clack and the valve seat can be normally inosculated, thereby achieving the aim of no steam leakage.

The concept and purpose of the present invention will be further understood from the following examples taken in conjunction with the accompanying drawings.

FIG. 1 is a longitudinal cross-sectional view of a trap in accordance with a preferred embodiment of the present invention.

Fig. 2 is a transverse cross-section at the position 1-1 in fig. 1.

Fig. 3 is a longitudinal sectional view of another embodiment of the present invention.

Referring to fig. 1 to 3, the housing [ 10 ] includes a housing [ 11 ], a valve seat [ 12 ], an inlet [ 13 ], an outlet [ 14 ], and a valve chamber [ 15 ]. The inlet is provided with a filtering device (16), the (16) is a screen plate in figure 1, and the (16) is a screen cylinder in figure 3, is clamped in a sewage discharge cover (17) and is sealed by a gasket (18). The heat-sensitive sensing element (20) comprises a rigid shell plum blossom shell (21) with an opening at one end, a heat-sensitive expansion body (22) which is formed by casting rubber (23) and a metal corrugated pipe (24) together is arranged in the shell, the metal corrugated pipe (24) contains an easily evaporated liquid (25), and a seal (26) is connected with the plum blossom shell (21) through screw threads. The valve flap (27) is inserted in the center of the seal (26), the tail end is embedded with a polytetrafluoroethylene top head (28), and a spring (29) is sleeved outside the valve flap (27). The setting device (30) is composed of an adjusting screw rod (31), a brake nut (32), a rear cover (33), a gasket (34) and an O-shaped sealing ring (35).

The function of the valve is as follows: the medium from the pipeline enters the valve cavity (15) through the filter device (16) at the inlet (13) and then flows through the gap between the valve clack (27) and the valve seat (12) through the outer groove of the plum blossom shell (21) to be discharged out of the valve. Assuming that the saturation temperature of steam and condensed water is T ℃, the position in the valve is adjusted, when steam and condensed water higher than T ℃ enter the cavity, the expansion body (22) expands with heat to close the closed port, and steam can not enter any more, when the condensed water lower than T ℃ enters, the expansion body (22) contracts to open the closed port with the spring force, so that the condensed water flows out of the valve through the outer groove of the plum blossom shell (21). The plum blossom shell has the function of converting the volume expansion amount (X, Y, Z three-degree expansion amount) of the expansion body (22) of the rubber (23) and the corrugated pipe (24) during thermal expansion into X axial displacement amount delta X, and the delta X is matched with the temperature T of the condensed water entering the cavity. That is, the higher T, the larger the DeltaX, the smaller the water displacement, and conversely, the lower T, the smaller the DeltaX, the larger the water displacement, which achieves our purpose.

Further explained from the principle of thermal static force, the thermal expansion body is composed of a first expansion element (23) rubber (the expansion amount of the body is DeltaV)₁) And a second expansion element (24) bellows (volume expansion amount is DeltaV)₂) Together forming a complex thermal expansion element having a total volume expansion of Δ V ═ Δ V₁+△V₂The first expansion element (23) rubber specially pointed out is used as a heat-sensitive element for expansion and contraction and is used for uniformly transmitting the volume change value DeltaV generated by the second expansion element (24) corrugated pipe in the expansion and contraction process₂. Since it is an elastic substance. Can be used forHas the capability of recovering the original shape during the heating process. The expansion body converts the expansion quantity delta V caused by temperature change into the displacement quantity delta X of the axial part assembly along the opening of the expansion body by the action of the rigid plum blossom shell, so as to operate the valve clack and realize the control of the opening size of the valve clack along with the temperature change of the flowing medium. Therefore, the purpose of steam-blocking and water-draining is achieved, and for the small-caliber steam trap, the expansion body only needs one element of the first expansion element (23) rubber, and the small-caliber steam trap can meet the requirement because the valve clack displacement of the small-caliber steam trap is smaller. When the liquid in the corrugated pipe is heated and vaporized to generate uniformly distributed acting force outwards, the liquid is also subjected to the uniformly distributed reaction force inwards generated by the external flexible rubber, the two uniformly distributed forces act on the wall surface of the shell, the directions are opposite, the numerical values are approximately equal, and therefore the forces are basically counteracted with each other, and the elastic tension borne by the shell is greatly reduced. The invention therefore also does not crack at higher steam pressures.

It can be seen that the thermally sensitive sensing element (20) and the flap (27) are biased, floating, and not rigidly connected relative to the valve seat (12) and the adjustment screw (31). The normal fit of the valve clack and the valve seat cannot be influenced by the actions of expansion and contraction.

It is worth to say that the corrugated pipe (24) is tightly attached to the bottom surface of the quincunx shell (21) to form a pot-bottom-shaped heating surface, and because the wave number is very small (generally only 2-3), although other surfaces are cast in the rubber (23), a part of direct heating surface is reduced, but the larger amount of body expansion is provided to compensate the situation.

When the valve is adjusted for the first time, the braking nut (32) can be loosened, the adjusting screw rod (31) can be screwed by a screwdriver, the braking nut (32) can be screwed when the water is only drained and the steam is not leaked at the discharge port, and the valve can be normally used after the adjustment is finished.

Claims

1. A steam trap consisting of a housing with a valve seat, a thermal sensing element and its adjustment device. Its characteristic is that the thermal expansion body is cast together with rubber and metal bellows and confined in a rigid shell with an opening at one end. The opening size of the valve disc is controlled by their body expansion.

2. The steam trap according to claim 1, wherein the rubber in the heat-sensitive expansion body can be fluororubber, ethylene propylene rubber, chloroprene rubber or a combination of the above rubbers.

3. The steam trap according to claim 1, wherein the metal bellows (24) is filled with an evaporable liquid (25).

4. The steam trap according to claim 1, wherein the rigid shell can be a plum blossom shell (21) whose open end is compressed by a seal (26), a valve disc (27) is inserted into the seal (26) and is in direct contact with the expansion body (22).

5. The steam trap according to claim 1, wherein the heat-sensitive sensing element (20) and the valve disc (27) are floating relative to the setting device and the valve seat (12) in the valve cavity.

6. The steam trap according to claim 1, wherein the filter device (16) provided at the inlet of the housing (11) can be a mesh plate or a mesh cylinder.

7. The steam trap according to claim 1 or 2, wherein for a small-diameter steam trap with a small disc displacement, the expansion body (22) is made of only one material, rubber (23).