JPS5825185B2 - Ball valve sealing mechanism - Google Patents

Description

[Detailed description of the invention] The present invention relates to a sealing mechanism for a ball valve.

Generally, as shown in FIG. 1, a ball valve has an annular valve seat holder 3 fitted into a fluid passage hole 2 of a valve housing 1 so as to be movable back and forth in the fluid flow direction. An annular valve seat 4 held in contact with the circumferential surface of the ball-shaped valve body 5 forms a fluid seal.

As shown in detail in FIG. 2, the valve seat holder 3 is composed of an inner ring 3a and an outer ring 3b that is fitted into the outer periphery of the inner ring 3a and is movable back and forth in the fluid flow direction, and the valve seat 4 has a round cross section. The mold is made of soft rubber with a hardness of up to 80° that exhibits sufficient sealing performance even under cold conditions, and is formed between the outer circumference of the tip of the inner ring 3a and the inner circumference of the tip of the outer ring 3b. The valve seat retaining groove 3c is fitted into the valve seat retaining groove 3c.
Publication No.).

By the way, in the ball valve having the above structure, when the ball-shaped valve body 5 is rotated in the direction of the arrow in FIG. There was a problem in that when facing the through hole 6 of the shaped valve body 5, that part of the valve seat 4 protruded from the holding groove 3c.

When the cause of this was investigated, it was found that the cause was that fluid pressure was acting on the valve seat 4 to cause it to pop out of the holding groove 3c.

That is, as shown in FIG. 2, when the ball-shaped valve element 5 is in the closed state, the ball-shaped valve element 5 contacts the circumferential surface of the ball-shaped valve element 5 at the seal point S1. However, on the other hand, they contact the wall surface of the valve seat holding groove 3c at a seal point t-82 to seal the respective fluids.

However, when a valve seat with a round cross section is used for the two seal points S1 and S2, the diameter d2 of one seal point S2 is generally larger than the diameter d1 of the other seal point s1.

Therefore, the fluid pressure p1 acts on the valve seat 4 in a direction that causes the valve seat 4 to pop out of the holding groove 3c, that is, in the fluid flow direction X.

For this reason, when the ball-shaped valve body 5 is rotated to perform an opening operation, the valve seat protrusion phenomenon occurs.

Therefore, the technical problem of the present invention is to make the diameter of the sealing point S1 with respect to the circumferential surface of the ball-shaped valve body larger than the diameter of the sealing point S2 with respect to the wall of the valve seat retaining groove, so that fluid pressure can be applied to the valve seat. The object is to act so that it can be pushed into the holding groove.

MEANS TO SOLVE THE PROBLEM In order to achieve the said technical problem, this invention was comprised as follows.

That is, on the outer periphery of the distal end of the inner ring, a groove with a cross-sectional shape is formed by an axis-parallel wall and an inclined wall whose outer circumference protrudes toward the distal end with respect to a surface perpendicular to the axis. An annular protrusion is formed on the inner periphery of the tip of the ring, and an axis-perpendicular wall is formed inside the protrusion, and the outer ring is fitted onto the outer periphery of the inner ring so that the inner peripheral wall of the outer ring and the protrusion are connected to each other. A valve seat holding groove is formed by the axis-perpendicular wall, the axis-parallel wall of the inner ring, and the inclined wall.

On the other hand, the rubber annular valve seat is formed to have a substantially rectangular cross section, the tip side surface and the opposite side surface are approximately parallel, and the inner peripheral surface is such that the diameter of the opposite corner is less than or equal to the diameter of the tip side corner. Further, the lateral thickness is approximately the same as or greater than the longest width of the sheet holding groove.

Then, this valve seat is press-fitted into the valve seat holding groove, and the tip side corner of the inner peripheral surface of the seat is opened into the valve seat holding groove formed between the protrusion of the outer ring and the tip of the inner ring. The ball-shaped valve body is made to protrude from the center and come into sliding contact with the circumferential surface of the ball-shaped valve body.

In the above configuration, since the width dimension of the valve seat is configured to be approximately the same as or greater than the longest width dimension of the valve seat holding groove, the leading end side and the opposite end side of the valve seat are respectively formed by the valve seat holding groove. Since the valve seat retaining groove is configured so that the outer circumferential side is pinched more tightly than the inner circumferential side, the valve seat is compressed more strongly in the retaining groove as the outer circumferential side As a result, the inner circumferential surface and the tip end corner portion on the inner circumferential side, which have a lower degree of compression, are displaced radially inward along the inclined wall and are located radially inward from the tip end corner portion.

When the valve is closed, the inner ring moves in the direction of the ball-shaped valve body relative to the outer ring due to the action of fluid pressure, generating a self-tightening force, and the inner circumferential surface and tip side corner are further displaced toward the inner diameter side. .

Therefore, the diameter dimension of the sealing point S1 with respect to the circumferential surface of the ball-shaped valve body, that is, the corner on the tip side of the inner circumferential surface of the valve seat is the same as the diameter dimension of the sealing point S2, that is, the inner circumferential surface of the valve seat with the tip side corner of the valve seat with respect to the inclined wall of the valve seat holding groove. This makes it possible to achieve the above technical problem and prevent the valve seat from popping out.

The present invention aims to achieve the above-mentioned technical problem by changing the cross-sectional shape of the valve seat and the cross-sectional shape of its holding groove from those of the conventional example and utilizing the rubber elasticity of the valve seat. It has the advantage that it is not more complicated than conventional ones and does not increase costs, and also has the advantage that it can exhibit sufficient sealing performance even under cold conditions.

The present invention will be specifically explained below with reference to the illustrated embodiment ζ.

The first embodiment will be explained based on FIGS. 3 to 6.

In FIG. 3, numeral 1 is a valve housing, 13a is an inner ring, 13b is an outer ring, and 5 is a ball-shaped valve body, the general construction of which is the same as that of the conventional example explained in FIGS. 1-2.

To explain the details in more detail, an annular groove 8 is provided at a predetermined location on the outer circumference of the inner ring 13a, and an annular collar 7 is fixed to the end surface of the outer ring 13b on the side facing away from the light. It is loosely fitted into the groove 8 of the inner ring 13a.

Therefore, the outer ring 13b moves the outer periphery of the inner ring 13a in the fluid flow direction
Can move back and forth.

In addition, the inner ring 13a has an annular groove 9 on its outer periphery.
a, 9b, and O-rings 10a, 10b are fitted into the grooves 9a, 9b, and the O-ring 10
a and 10b are brought into contact with the inner peripheral surface of the valve housing 1 to seal the fluid.

Further, a spring chamber 12 containing a spring 11 is provided at a predetermined position on the inner peripheral surface of the valve housing 1.

One end of this spring 11 is in contact with the end wall 12 of the inner ring 13a on the side opposite to the light.
The entire area a is constantly pressed in the fluid flow direction X.

The valve seat holding groove 13C is formed as follows.

That is, a piece 22 having a roughly oval-shaped cross section is provided at the outer peripheral tip of the inner ring 13a.

This single load 22 includes an axis-parallel wall 15 that forms a surface in the same direction as the fluid flow direction X, that is, the axial direction of the inner ring;
It is formed by an inclined wall 16 whose outer peripheral side is inclined so as to slightly protrude toward the distal end with respect to the plane perpendicular to the axis.

On the other hand, the outer ring 13b has a protrusion 17 at the tip of its inner circumference, and an axis-perpendicular wall 18 formed inside the protrusion 17.
and the inner circumferential wall 19 of the outer ring form a single load 20 having a roughly oval-shaped cross section.

Thus, a valve seat holding groove 13c having a generally rectangular cross section is formed by the piece 22 of the inner ring 13a and the piece 20 of the outer ring 13b.

However, an opening 21 is provided between the protrusion 17 of the outer ring 13b and the tip of the axis-parallel wall 15 of the inner ring 13a.
is formed.

On the other hand, the cross-sectional shape of the rubber annular valve seat 14 is
As shown in the figure, the cross-sectional shape is approximately the same as that of the valve seat holding groove 13c.

That is, the outer circumferential surface 14a and the inner circumferential surface 14b, and the distal end side surface 14c and the opposite end side surface 14d are parallel to each other, and have a generally rectangular cross section.

However, the tip side corner portion 23 of the inner circumferential surface 14b is rounded.

The horizontal thickness t2 of the valve seat 14 is the same as the longest width L2 of the valve seat holding groove 13c, and the vertical thickness t3 of the valve seat 14 is the same as the vertical width of the valve seat holding groove 13c. It is smaller than L3.

The valve seat 14 having the above structure is fitted into the valve seat holding groove 13c and deformed as shown in FIG. 5.

That is, since the width dimension of the valve seat holding groove 13c becomes narrower toward the outer circumference, the side surface 14d of the opposite end of the valve seat 14 is compressed nonuniformly.

In other words, as a result of the outer side of the valve seat 14 being strongly compressed,
The corner portion 24 of the valve seat opposite to the light side moves toward the inner diameter side of the tip corner portion 23 along the inclined wall 16.

The tip side corner portion 23 protrudes from the opening 21 of the valve seat holding groove 13c and comes into contact with the circumferential surface of the ball-shaped valve body 5.

Therefore, this contact point S1 becomes a sealing point for the circumferential surface of the ball-shaped valve body 5.

Note that a certain clearance C is formed between the inner peripheral surface 14b of the valve seat 14 and the axis-parallel wall 15 of the valve seat holding groove 13c.

Now, when the fluid pressure P1 acts on the inner ring 13a,
Since it is larger than the sealing point diameter d1 with respect to the inner circumferential surface of the valve housing 1, the inner ring 13a moves in the fluid flow direction X and generates a so-called self-tightening force.

FIG. 6 shows this state. Then, as shown in FIG. 6, the side surface 14d of the valve seat 140 opposite to the tip end is further pressed against the inclined wall 16 of the valve seat holding groove 13, and the corner portion 24 on the opposite end side is further pushed further than the corner portion 23 on the front end side. Move inward.

Also, the inclined wall 16 on the side surface 14d of the opposite end of the valve seat 14
The surface pressure on the surface increases as it moves outward.

Then, the fluid flows through the opposite light end side surface 14 of the valve seat 14.
d, the valve seat holding groove, and the inclined wall 16 of the valve seat holding groove 13c. Point S2
becomes.

Therefore, since the diameter d1 of one seal point S1 is larger than the diameter d2 of the other seal point S2, the fluid pressure P1 acts to push the valve seat 14 into the valve seat holding groove 43c.

Therefore, even when a part of the valve seat 14 faces the through hole 6 of the ball-shaped valve element 5 when opening the ball-shaped valve element 5, it is prevented from jumping out of the valve seat holding groove 13c. It will be done.

As shown in FIG. 7, the seat valve 14 has an inner peripheral surface 14
b may be inclined from the beginning, and the corner portion 24 on the side opposite to the light end may be located inside the corner portion 23 on the tip side.

The seat valve 14 having this shape has a valve seat holding groove 4
3c, the position of the sealing point S2 moves further inward, making it more effective.

As shown in FIG. 8, if a passage 25 is provided in the inner ring 13a that opens at a position outside the seal point 1-82 of the inclined wall 16 and, for example, into the groove 8, the passage 2
Since the internal pressure of the cavity 26 formed outside the seal point S1 is the same as the pressure P2 of the cavity 26, even if the seal point S2 moves to the outside for some reason, the fluid will not escape from the passage 25. can.

Therefore, the seal point will no longer move outward, and the valve seat 14 can be prevented from coming off.

As explained above, the ball valve sealing mechanism according to the present invention changes the sealing point diameter of the valve seat with respect to the ball-shaped valve body by changing the conventional cross-sectional shapes of the valve seat holding groove and the valve seat. The diameter of the sealing point relative to the wall surface of the retaining groove can be made smaller, thereby making it possible to effectively prevent the valve seat from slipping out of the retaining groove.

[Brief explanation of drawings]

Figure 1 is a sectional view of the main parts showing the general structure of a ball valve;
FIG. 2 is a sectional view showing a conventional sealing mechanism, FIGS. 3 to 8 show an embodiment of the present invention, FIG. 5.6 is an enlarged sectional view of the main part of FIG. 3, FIG. 7 is a sectional view showing a modified example of the valve seat, and FIG. 8 is a seal mechanism according to another embodiment. FIG. DESCRIPTION OF SYMBOLS 1... Valve housing, 2... Fluid conduction hole, 5... Ball-shaped valve body, 6...
Through hole, 13a... Inner ring, 13b.
...Outer ring, 14...Valve seat, 14a...Outer circumferential surface, 14b...
Inner peripheral surface, 14c...Tip side, 14d...
...Anti-light end side, 15...Axis-parallel wall, 16...
... Slanted wall, 17 ... Projection, 18 ...
...Axis-perpendicular wall, 19...Inner peripheral wall of outer ring, 20.22...One load, 21...Opening, 23...Tip side corner part , 24... Corner portion on the opposite side of the light end.

Claims (1)

[Claims] 1. On the outer periphery of the tip of the inner ring, a groove with a cross-sectional shape is formed by an axis-parallel wall and an inclined wall whose outer circumferential side projects toward the tip with respect to the plane perpendicular to the axis.
An annular protrusion is formed on the inner periphery of the tip of the outer ring, and an axis-perpendicular wall is formed inside the protrusion, and the outer ring is fitted onto the outer periphery of the inner ring so that the inner peripheral wall of the outer ring and the protrusion are formed. A valve seat holding groove is formed by the axis-perpendicular wall of the strip, the axis-parallel wall and the inclined wall of the inner ring, and the rubber annular valve seat is formed to have a substantially rectangular cross section, with the tip side surface and the opposite light end side surface being approximately parallel to each other. At the same time, the inner circumferential surface is formed so that the diameter of the corner on the opposite end side is less than or equal to the diameter of the corner on the front end, and the lateral thickness is approximately the same as or equal to the longest width of the sheet holding groove. As above,
This valve seat is press-fitted into the above-mentioned valve seat holding groove, and at the same time, the tip side corner of the inner peripheral surface of the seat is projected from the opening of the valve seat holding groove formed between the protrusion of the outer ring and the tip of the inner ring. A sealing mechanism for a ball valve, characterized in that it is at least in sliding contact with the circumferential surface of a ball-shaped valve body.