JPH0211662Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Field of Industrial Application] The present invention relates to ball valves, and in particular, a pressure relief function that effectively releases the pressure inside the cavity of a floating ball type ball valve when the pressure inside the cavity increases abnormally. This invention relates to a valve seat for a ball valve having a ball valve. [Prior Art] When the pressure inside the body cavity of a ball valve increases abnormally due to a rise in temperature or vaporization of the fluid, the valve seat, body, ball, etc. may be deformed, damaged, or broken, resulting in a reduction or loss of function of the ball valve. A situation arises. As a countermeasure against such an abnormal pressure increase in the body cavity, a thin groove is provided in the tongue-shaped part of the valve seat that is pressed into contact with the ball surface, and the valve seat is configured to be easily elastically deformed in this groove. The increased pressure pushes this tongue apart and allows it to escape. For example, the device described in Japanese Utility Model Application Publication No. 56-82360 corresponds to this. According to this, the tongue-like part (lip-like part) 9b has a thickness of _T1 , and a groove 13 is cut on the opposite side of the contact surface of the tongue-like part 9b with the ball surface. A thin piece part 9c having a thickness _T2 smaller than ₁ is formed so that abnormal pressure increase in the cavity part (valve chamber space) spreads the contact surface of this thin piece part 9c with the ball surface and escapes. [Problem to be solved by the invention] However, in such a structure, since the thin piece part 9c is present in the annular tongue part 9b, the ball is not affected by the circumferential elastic force of the tongue part as a whole. The pressure contact force against the valve seat becomes weak and the valve seat easily deforms, and in particular, the thin section 9c tends to stretch in the circumferential direction of the valve seat and undergo plastic deformation, resulting in excessive deformation and deterioration of sealing performance. It becomes necessary. As mentioned above, the conventional valve seat, which is designed to release abnormal pressure increase in the cavity of a floating ball valve, has the problem that the valve seat is prone to plastic deformation, resulting in poor sealing performance and durability. . The present invention aims to solve this problem and provide a valve seat for a ball valve that can efficiently eliminate abnormal pressure increase in the cavity and has good sealing performance and durability. [Means for Solving the Problems] In order to achieve the above object, the present invention provides an annular valve seat installed between a step formed inside the body of a ball valve and a ball having a through hole. an engaging surface formed from the outside in the radial direction of the valve seat body and from the outside in the radial direction of the valve seat body is brought into contact with the stepped portion, and a radial direction of the valve seat body located on the opposite surface of the engaging surface is brought into contact with the step portion. A shoulder portion is formed with the slightly inner side in contact with the ball surface, and a tongue-shaped portion is formed on the radially inner circumferential surface of the valve seat body to be brought into contact with the ball surface.
Furthermore, the valve seat body forms an annular space between the contact zone of the tongue portion with the ball surface and the contact zone of the shoulder portion with the ball surface, in which the valve seat body does not come into contact with the ball surface; , forming a communication groove that communicates with the space from a cavity portion defined by the body, the pair of valve seat bodies, and the ball surface, and carving an appropriate number of grooves in the lower end of the engagement surface of the shoulder portion; A configuration was adopted. Further, the communication groove and the groove portion may be formed in both or one of the valve seat bodies of the pair of valve seats. [Function] The floating ball type ball valve of the present invention has a contact zone that comes into contact with the ball surface on the shoulder and tongue portion of the valve seat, and an annular space that does not come into contact with the ball surface in between. It has a department. A communication groove communicating from the cavity to this annular space is formed in the shoulder. Therefore, the abnormal pressure increase in the cavity reaches the annular space through this communication groove.
Furthermore, an appropriate number of grooves are cut into the lower end of the engagement surface of the shoulder. In other words, in the cross section forming this groove, the tongue is extended longer than the other tongues, reducing the cantilever-like repulsive contact force and reducing the annular space. The area of the tongue-shaped portion on which pressure acts increases, and the contact surface with the ball surface is pushed out with a lower pressure than other portions, allowing the pressure in the annular space to be released to the flow path of the valve.
Since the annular space communicates with the cavity as described above, abnormal pressure buildup within the cavity is released by pushing the tongue-shaped portion with the groove apart. Although it has the function of eliminating abnormal pressure build-up within the cavity, it does not have a pressure relief function because the thickness of the tip of the tongue is uniform over the entire circumference regardless of the presence or absence of the groove. It is possible to provide a valve seat that has the same sealing performance and durability as the valve seat. [Examples] Examples of the present invention will be described in detail below with reference to the drawings. In the drawings, reference numeral 1 denotes a valve body, which forms an inflow side (primary side) 2 on one side and an outflow side (secondary side) 3 on the other side. 4 is a ball rotatably provided in the valve chamber of the body 1 with a stem 5 attached to the upper part thereof, and is provided so as to communicate liquid through a through hole 6 formed in the ball 4; To do this, the fluid is blocked by the ball surface 4a of the ball 4 by rotating the handle 7 or the like. Reference numeral 8 denotes a pair of annular valve seat bodies mounted between the stepped portions 9, 9 formed inside the body 1 and the ball surface 4a, and the inner peripheral surface 8 of the valve seat body 8 in the radial direction
A tongue-shaped portion 10 is formed on the ball surface 4a, and the tongue-shaped portion 10 is elastically deformed to contact the ball surface 4a.
a, and the engagement surface 12 formed from the outside of the valve seat body 8 in the radial direction and from the outside in the radial direction of the valve seat body 8 is brought into contact with the stepped portion 9, and this engagement surface A shoulder portion 11 is formed in which the slightly inner side in the radial direction of the valve seat body 8 located on the opposite surface of the valve seat body 12 contacts the ball surface 4a. 13 is an annular space formed in the valve seat body 8, and this space 13 is provided between the contact zone between the tongue portion 10 and the ball surface 4a and the contact zone between the shoulder portion 11 and the ball surface 4a. This is a space in which the ball-side intermediate portion of the valve seat body 8 does not come into contact with the ball surface 4a. Reference numeral 14 designates a cavity section defined between the body 1, the pair of valve seat bodies 8, and the ball surface 4a, and 15 designates a communication groove that communicates from the cavity section 14 toward the space 13. An appropriate number of numerals 15 are formed on the shoulder portion 11. 16 is a groove formed in the lower end 12a of the engagement surface 12 of the shoulder 11, and this groove 16
This is a groove that is on the same plane as the plane of 0 and cuts into an appropriate position toward the shoulder portion 11 on the outside in the radial direction. The above-mentioned communication groove 15 and groove part 16 are connected to the third
In the figures and FIG. 4, they are provided above and below the symmetrical positions of the valve seat main body 8, but the present invention is not limited to this, and one or more arbitrary numbers may be provided at appropriate positions. , the pair of valve seat bodies 8 shall be provided with a communication groove 15 and a groove part 16 in one or both of them. For example, when provided in the valve seat body 8 on the primary side, the abnormal pressure in the cavity part 14 will be In addition to flowing out into the flow path, when provided in both valve seat bodies 8, the abnormal pressure in the cavity part 14 flows out at the valve seat where the communication groove 15 and the groove part 16 are provided.
Piping can be freely connected without being affected by the direction of the fluid flow path. Note that the pressure within the allowable range within the cavity portion 14 can be set arbitrarily by changing the length and width of the groove portion 16 formed toward the shoulder portion 11 as appropriate. Next, the operation of the above embodiment will be explained.
When the ball 4 is rotated in the valve open state shown in FIG. 1 to bring the through hole 6 of the ball 4 into a state perpendicular to the flow path, the fluid is closed. At this time, the valve seat main body 8 on the secondary side is pressed by the ball 4 pushed by the fluid pressure, and this pressing force is received by the shoulder portion 11, so there is no damage or deformation of the tongue portion 10, and the valve seat body 8 is pressed by the ball 4 pushed by the fluid pressure. In addition to sealingly contacting the ball surface 4a in an elastically deformed state, the tongue-like portion 10 of the primary side valve seat body 8 is elastically deforming and in contact with the ball surface 4a, and further fluid pressure is applied to the ball surface 4a. Ensures sealing contact. In this state, the fluid inside the cavity part 14

【table】

[Table] Table 1 shows the cavity from the drain hole in the center of the body of a valve with a nominal diameter of 8B incorporating a pure PTFE valve seat shown in Fig. 5a as a partial front view and Fig. 6b as a partial sectional view. This figure shows the results of an investigation into the pressure relief of the valve seat when the valve seat is pressurized. 60 if the width of the groove formed on the valve seat is 10mm
Pressure relief did not occur even when pressurized to Kgf/cm ² , but when the groove width was set to 15 mm, 50 kg
Pressure relief was applied at f/cm ² . Table 2 shows the pressure applied to the cavity from the drain hole in the center of the body of a valve with a nominal diameter of 1B incorporating a pure PTFE valve seat shown in Figure 6a as a partial front view and Figure 6b as a partial sectional view. This figure shows the results of an investigation into the pressure relief of the valve seat. When the width of the groove formed on the valve seat is 3 mm,
Pressure relief did not occur even when pressurized to 100Kgf/ ^cm2 , but when the groove width was set to 3.5mm,
Pressure relief was applied at 40Kgf/ ^cm2 . The results of both experiments were based on the valve seat having the structure of the present invention as shown in FIGS. It has been shown in fact that pressure relief can be achieved with a desired pressure. [Effects of the invention] As is clear from the above, according to the invention, the pressure relief function can be effectively exerted by the valve seat body against abnormal pressure in the cavity, and moreover, It has the advantage of significantly improving durability and performance compared to valve seats.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and Fig. 1 is a longitudinal sectional view of the valve according to the invention, Fig. 2 is a partially enlarged sectional view showing the same valve seat portion, and Fig. 3 is a valve seat. FIG. 4 is a perspective view showing the communication groove of the valve seat, and FIGS. 5a and 5b are
Figures 6a and b are a partial front view and a partial cross-section showing the shape and dimensions of the valve seat used in the experiment. It is a diagram. DESCRIPTION OF SYMBOLS 1... Body, 4... Ball, 4a... Ball surface, 6... Through hole, 8... Valve seat body, 8a... Inner peripheral surface, 9... Step part, 10... Tongue part, 11 ...shoulder part, 12...engaging surface, 12a...lower end, 13...
...Space part, 14...Cavity part, 15...Communication groove, 16...Groove part.

Claims (1)

[Claims for Utility Model Registration] (1) In an annular valve seat installed between a stepped portion formed inside the body of a ball valve and a ball having a through hole, the valve seat is installed from the outside in the radial direction of the valve seat body and from the outside. An engagement surface formed in the radial direction of the seat body is brought into contact with the stepped portion, and a slightly inner side in the radial direction of the valve seat body located on the opposite surface of the engagement surface is brought into contact with the ball surface. In addition to forming the shoulder portion, a tongue portion is formed on the inner circumferential surface of the valve seat body in the radial direction to be in contact with the ball surface, and the contact zone of the tongue portion with the ball surface and the ball surface of the shoulder portion are further formed. The valve seat body forms an annular space between the contact zone and the ball surface where the valve seat body does not come into contact with the ball surface. A ball valve having a pressure relief function, characterized in that a communication groove communicating with the space is formed, and an appropriate number of grooves are carved on the lower end of the engagement surface of the shoulder. seat. (2) A valve seat for a ball valve according to claim 1 of the utility model registration claim, in which a communication groove and a groove portion are formed in the main body of one of a pair of valve seats. (3) A valve seat for a ball valve according to claim 1 of the utility model registration claim, in which a communicating groove and a groove portion are formed in the main bodies of both valve seats of a pair of valve seats.