JPS5926830B2 - safety valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a safety valve that opens at a pressure equal to or higher than a set pressure.

FIG. 1 shows the valve body and valve seat of the most commonly used safety valve.

In order to prevent leakage, the safety valve with this structure applies a strong pressing force per unit area of the sealing surface even just before the valve element 1 opens, that is, when the pressure inside the valve seat "2" is at its maximum. There is a need.

This can be achieved by narrowing the width of the sealing surface to reduce the contact area.

However, if this area is made smaller, the spring load of the spring, which is a suppressing member that presses the valve body 1 against the valve seat 2, will be supported only by the sealing surface of the valve body 1 when the pressure inside the valve seat mouth is zero. Therefore, there is a drawback that the contact direction of the valve seat 2 and the valve body 1 is damaged.

Therefore, if the sealing surface of the valve body 1 is widened, the shutoff pressure per unit area is reduced, which tends to cause leakage (and if this is made small, the contact surface is damaged, causing leakage).

In order to eliminate this drawback, a valve body having the structure shown in FIG. 2 was developed.

In the device shown in Fig. 2, the spring load is received by the protect ring 3, thereby reducing the pressing force on the sealing surface 4 when the valve seat port internal pressure is zero, and when the valve seat port internal pressure increases, this pressure and the spring load are reduced. As well as being balanced, this pressure causes lip 5
is pressed against the valve seat 2 to reduce leakage, and the valve body 1 with this structure has a sealing surface 4 when the internal pressure at the valve seat opening is zero.
It has the feature that the pressing force of the sealing surface 4 can be reduced and the pressing force of the sealing surface 4 can be increased when the internal pressure of the valve seat opening is high. As shown in FIG. 3, the protect ring 3 is lifted by pressure, and the outer side of the sealing surface 4 is also separated from the valve seat 2, so that the sealing surface 4 comes into close contact with the valve seat only at the inner end. Since sealing is performed only in this area, the surface roughness of the inner edge of the sealing surface, that is, the tip edge of the lip, determines the quality of the sealing performance. Since the lip is sealed at an extremely narrow portion of the edge, the pressure drop at the tip of the lip is extremely large, and this portion has the disadvantage of being easily eroded.

Further, the improved valve body 1 having the structure shown in FIG.
The resoiner ring 7 is brought into contact with the -H surface of the valve, and when the pressure is high, the resoiner ring 7 is separated from the upper surface of the lip 5, and this pressure presses the sealing surface 4 of the lip 5 against the valve seat 2. However, in a valve body with this structure, when the pressure is zero, all the spring load is applied to the sealing surface 4 of the lip 5, so the width of the sealing surface 40 can be narrowed. Since the sealing surface is pulled away from the outer periphery, the sealing surface is brought into close contact with the valve seat only at the inner edge, resulting in similar problems, similar to those described above.

In addition, in the valve body of this structure, the sealing surface 4 is rubbed together on a flat surface plate, so when in use, the pressure gradually decreases from the maximum pressure and the load on the valve body gradually increases.
The lip 5 receives this force, and the upper surface of the lip 5 is deformed to the point where it is strongly pressed against the resoiner ring 7, and as a result, the position where the sealing surface of the lip 5 most tightly contacts the valve seat is near the outer periphery of the sealing surface. Become.

For this reason, if the inner edge of the sealing surface 4 is damaged even if it is slight and the sealing performance is reduced, high-pressure steam inside the valve seat will penetrate to the outer periphery of the sealing surface, causing the valve body 1 to become less effective. There was a drawback that the pressure receiving area increased and the valve body 1 was lifted up, further deteriorating the sealing performance.

The present invention has been developed to eliminate these drawbacks; an important objective of the present invention is to provide a complete and leak-free seal.
To provide a safety valve in which corrosion does not occur on the sealing surface of a valve body and a valve seat, and in addition, the width of the cylindrical ring sealing surface can be narrowed so that this part can be finished to a more perfect mirror finish.

Embodiments of the present invention will be described below based on the drawings.

In this specification, the vertical direction is determined based on the drawings.

The safety valve shown in FIG. 5 includes a valve body 1 that is brought into close contact with an annular, planar valve seat by a pressing member such as a spring.

The valve body 1 includes a cylindrical ring 8 and a protect ring 3, and the cylindrical ring 8 consists of a cylindrical portion 8A and a bent portion 8B, and the central axis of the cylindrical portion 8A is in the moving direction of the valve body, as shown in FIG. The cylindrical part 8 is integrated into the valve body so as to face in the vertical direction.
The upper part of A is bent outward to form a bent portion 8B, and the bent edge of the bent portion 8B is fixed to the valve body.

The bent portion 8B is formed by the sealing surface 4 at the lower end due to the internal pressure of the valve seat port.
The upper surface of the bent portion 8B is communicated with the valve seat 19 so that the bent portion 8B is pressed against the valve seat 2, and a pressure receiving portion 10 is formed here.

When the internal pressure at the valve seat opening is low, the bending portion 8B or between the bending portion 8B and the valve body connecting portion is formed so that more of the spring load is applied to the protect ring 3. Furthermore, under the pressure inside the valve seat opening, where the pressure inside the valve seat opening is high (as shown in FIG. 7), the cylindrical ring It has the elasticity to push out the cylindrical portion 8A from the protect ring.

By the way, in a state where no stress is applied to the valve body 1, the cylindrical ring 8, and the protect ring 3, the sealing surface 4 at the lower end of the cylindrical ring is in close contact with the valve seat when the internal pressure is zero. As shown in FIG. 5, it is preferable that the sealing surface 4 of the cylindrical ring protrudes from the contact surface 6 of the protect ring.

However, like the conventional safety valve shown in FIG. 2, the seal 4 surface is formed to be flush with the contact surface 6 of the protect ring with no stress acting on the valve body 1, cylindrical ring 8, and protect ring 3. Needless to say, the sealing surface 4 can be brought into close contact with the valve seat 6.

When the pressure is low, the sealing surface 4 of the cylindrical ring 8 becomes flush with the contact surface 6 of the protect ring, as shown in FIG. , as shown in FIG. 7, the contact surface 6 of the protect ring is lifted from the valve seat 2, and only the sealing surface 4 of the cylindrical ring is in close contact with the valve seat, that is, the cylindrical portion 8A is moved by pressure. The bending portion 8B or the connecting portion between the bending portion and the valve body is required to have elasticity to move up and down.

This elasticity allows the cylindrical ring 8 to
, 1, by using a metal with an elastic modulus that is easier to deform than the ring, or by reducing the wall thickness of the bent portion 8B or between the bent portion 8B and the valve body connection point. .

As shown in FIG. 7, the length of the cylindrical ring 80 and the cylindrical portion 8A are as follows, even when the bent portion 8B protrudes downward from the contact surface 6 of the protect ring under the pressure inside the valve seat opening. The length is such that the sealing surface 4 of the cylindrical ring 8 does not touch the valve seat at an angle and is always maintained in surface contact, that is, the cylindrical portion 8A does not deform into a widening shape (cylindrical shape) in the state shown in FIG. The length is determined so that it can be held and moved up and down.

As shown in FIGS. 6 and 7, the cylindrical portion 8 of the cylindrical ring
As long as A can be translated up and down relative to the valve seat 2 while maintaining its cylindrical shape, the sealing surface 4 of the cylindrical ring will be translated relative to the valve seat 2.

As shown in FIG. 3, in the conventional valve body, when the pressure inside the valve seat mouth becomes high and the lower surface of the protect ring 3 is separated from the valve seat 2, the sealing surface 4 of the lip 5 is moved away from the valve seat 2. tilted against.

This is because the lip 5 is deformed into a widening shape due to the protect ring 3 rising relative to the lip 5.

That is, the lip 5 pushed out below the protect ring 3 which has risen away from the valve seat 2 causes the valve seat 2 to be deformed into a shape in which the diameter of the lower end becomes wider due to the internal pressure, thereby causing the sealing surface 4 to become closer to the valve seat 2. tilted against.

In order for the entire sealing surface 4 of the cylindrical ring 8 to move parallel to the valve seat 2, the cylindrical portion of the cylindrical ring 80 must not be deformed into a widening shape (move parallel to the valve seat 2 while remaining cylindrical). There is a need to.

In order to realize this characteristic, the cylindrical ring 8 of the present application has a sufficient length for the cylindrical portion 8A, and furthermore, the cylindrical portion 8A is provided at the bending portion 8B or at the connection point between the bending portion 8B and the valve body. It has elasticity that allows it to move up and down while remaining cylindrical.

The protect ring 3 is disposed on the outside of the cylindrical ring 8 as shown in FIG. 5, or as shown in FIG. As shown, it is arranged inside the cylindrical ring 8.

When the protect ring 3 is formed outside the cylindrical ring 8, by bringing the outer peripheral surface of the cylindrical ring 8 into slidable contact with the inner surface of the protect ring 3, the cylindrical ring can be prevented from being expanded by pressure.

Therefore, according to this structure, the cylindrical ring 8 is made considerably thin (
This allows the sealing effect to be ideally improved, and by forming the grooves 11 in the radial direction on the contact surface 6 of the protect ring 30, the pressure on the contact surface 6 of the protect ring immediately after the valve body is seated can be quickly released. be able to.

The protect ring 3 is located inside the cylindrical ring 8,
Moreover, when the inner surface of the cylindrical ring 8 contacts the outer surface of the protect ring, ventilation is provided between the cylindrical ring 8 and the protect ring 3, and the groove 11 formed above the cylindrical ring is inserted into the valve seat opening 9. The pressure receiving surface 10 on the upper surface of the bent portion of the cylindrical ring is configured to apply internal pressure to the valve seat opening.

In the safety valve according to the present invention, when the pressure inside the valve seat opening is small or zero, the sealing surface of the cylindrical ring comes into close contact with the valve seat, and most of the pressing force of the pressing member is caused by the protection ring coming into contact with the valve seat. It is held by supporting force.

Therefore, no excessive force is applied to the sealing surface of the cylindrical ring.

When the pressure inside the valve seat mouth increases, the pressure-receiving surface of the cylindrical ring receives this pressure and the sealing surface is brought into close contact with the valve seat with strong force, resulting in high sealing performance.The pressure also increases and the protect ring separates from the valve seat. Even in this state, the cylindrical part of the cylindrical ring maintains its cylindrical shape and moves relative to the protect ring, so even in this state, the sealing surface of the cylindrical ring is in close surface contact with the valve seat, and the sealing surface The entire width of the valve seat is in close contact with the valve seat.
Excellent sealing performance is maintained and no leakage occurs.

The sealing surface of the cylindrical ring is in close contact with the valve seat over its entire width.
Compared to conventional sealing at the extremely narrow portion of the tip edge, the pressure drop per unit length parallel to the radial direction of the sealing surface is lower, resulting in less leakage, no corrosion, and improved sealing performance. This produces an effect that is not affected by the condition of the inner end surface of the cylindrical ring.

Furthermore, since the width of the sealing surface 10 of the cylindrical ring can be narrowed, mirror finishing of this surface is easy.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the valve body and valve seat of a conventional safety valve, FIGS. 2 and 3 are cross-sectional views showing the corroded state of the valve body and valve seat according to another conventional example, and FIG. FIG. 2 is a sectional view showing still another conventional example. 5 to 8 are cross-sectional views showing a valve body and a valve seat of a safety valve according to an embodiment of the present invention. 1... Valve body, 2... Valve seat, 3...
...Grotect ring, 4... Seal surface, 5.
...lip, 6...hit, 7...
・Retainer ring, 8...Cylindrical ring, 9・
...Valve seat port, 10...Pressure receiving surface, 11...
····groove.

Claims (1)

[Claims] 1. An annular valve seat, a valve body that is in close contact with the valve seat, and a suppressing member that presses against the valve seat, and a pressure greater than a predetermined pressure is applied to the valve body. In the past, in a safety valve in which the valve body was separated from the valve seat and opened when this became larger than the pressing force of the suppressing member, the valve body consisted of a valve body, a cylindrical link, and a protect ring, and the cylindrical ring was made up of a cylindrical portion and a protect ring. The upper part of the cylindrical part is bent in the radial direction to form the bent part, and the central axis of the cylindrical part is parallel to the direction of movement of the valve body.
In addition, the bent edge of the bent portion is connected to the valve body so that the cylindrical portion can move the required distance in the axial direction relative to the protect ring.
One side of the bent portion is communicated with the valve seat opening to form a pressure receiving surface, and the cylindrical portion can maintain its cylindrical shape under pressure inside the valve seat opening when the protect link is separated from the valve seat. In addition, when the protect ring is separated from the valve seat, it deforms itself and the cylindrical portion is formed relative to the protect ring. Furthermore, the sealing surface at the lower end of the cylindrical ring is in contact with the cylindrical ring! −'
It is formed in a shape that comes into close contact with the valve seat in a state where the pressure inside the valve seat is zero and no stress is applied to the valve seat, and furthermore, the circle t=
'+') When the pressure inside the valve seat mouth increases, the force with which the protect ring's contact surface presses against the valve seat decreases, and when the pressure inside the valve seat (L-) increases, the contact surface of the protect ring However, in the cylindrical link, the pressure receiving surface of the bent part is pressed by the pressure inside the valve seat [21], and the bent part or the connecting part between the bent part and the valve body is elastically deformed, and the cylindrical part has a cylindrical shape. is held so that the sealing surface at the lower end is in close surface contact with the valve seat.Furthermore, when the pressure inside the valve seat mouth rises and reaches -H below the set pressure, the valve body is pushed up by the pressure inside the valve seat mouth and the cylindrical A safety valve in which the cylindrical part of the ring moves upward in parallel, and the sealing surface at the lower end is separated from the valve seat, opening the valve. 2. The safety valve according to claim 1, wherein the protect ring is disposed inside the cylindrical ring. 3. The safety valve according to claim 1, wherein the protect ring is disposed outside the cylindrical ring, and the outer surface of the cylindrical ring slidably contacts the inside of the protect ring. 4. The safety valve according to claim 3, wherein a radial groove is carved in the contact surface of the protect ring that is in close contact with the valve seat. 5. The safety valve according to claim 1, wherein the cylindrical ring is made of an elastic material that is more easily deformed than the protect link.