JP2009103242A - Ball valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve sealability when using packing formed of a non-self-sealing raw material such as expansion graphite, in a seal structure of seat rings of a floating type ball valve. <P>SOLUTION: Seal installing parts 35 and 36 are formed on an outer diameter surface of the primary side and secondary side seat rings 29 and 30. Seal members 27 and 28 and seal pressing members 37 and 38 are respectively fitted to its seal installing parts 35 and 36 by contacting with an outer end surface of the respective seal members 27 and 28. The seal pressing members 37 and 38 are pressed by both disc springs 56. Compressive force by pressing force P1 of the disc spring 56 and pressing force P2 by opposite side fluid pressure acting via a valve element 26, is made to act on any of the seal member 27 or 28. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a ball valve, and more particularly to a seal structure in a floating ball valve.

  A ball valve is conventionally known as a valve for opening and closing pipelines for various powders and fluids. Particularly, a metal seat ring that supports a metal ball-shaped valve body is excellent in durability, and is conventionally known as a metal touch type (Patent Document 1).

  The basic structure of a conventional metal touch type ball valve consists of a casing provided with a valve chamber between a primary side and a secondary side opening, a bonnet that closes the valve chamber, and a bonnet that is rotatable. A ball-shaped valve body supported and housed in the valve chamber, primary and secondary seat rings inserted through seal members in the primary and secondary openings, respectively, and each seat ring Are respectively provided with pressing means for pressing the valve body against the primary side and secondary side ports.

  The seal member of the seat ring is formed by an O-ring which is a self-sealing seal member, and the O-ring is mounted in a seal groove formed in the circumferential direction on the outer diameter surface of the seat ring. The O-ring is pressed against the inner diameter surface of the opening of the casing by its own elasticity to seal the seat ring.

  As the support structure of the valve body in the ball valve, a support shaft projecting at a position symmetrical to the valve shaft is inserted and supported in a shaft hole on the bottom surface of the valve chamber to support the valve shaft and the support shaft at two locations. Trunnion type and floating type in which the support shaft is omitted and the valve body is supported only by the valve shaft.

  In the case of the floating type, for example, when the fluid pressure on the primary side is relatively high, the valve body is displaced to the secondary side and is pressed against the secondary side seat ring. At this time, the seat ring on the primary side moves following the valve body that is pushed by the pushing means at the rear end and is displaced to the secondary side. On the other hand, when the fluid pressure on the secondary side is relatively high, the valve body is displaced to the primary side and pressed by the primary side seat ring, and the secondary side seat ring follows the valve body. Since the trunnion type is constrained to the casing by the support shaft, the above displacement cannot occur due to the fluid pressure.

  In addition to the spring force of the disc spring that directly presses the seat ring, the fluid pressure acts on the contact surface between the floating seat ring and the valve body as described above, so a high sealing performance is achieved with a relatively small spring force. There are features to be obtained.

  In the ball valve, the O-ring for sealing the seat ring is a sealing member suitable for a floating ball valve in that it does not hinder the smooth displacement of the seat ring.

  One factor that determines the use limit temperature of the ball valve is the heat resistance of the O-ring. In the case of a conventional rubber O-ring, the use limit temperature was about 200 ° C. from the viewpoint of heat resistance. In order to increase the use limit temperature, it is conceivable to use a heat resistant material such as expanded graphite packing instead of the O-ring.

  However, since the expanded graphite packing has poor elasticity and does not have a self-sealing property, like an O-ring, it is elastically expanded and fitted to the outer diameter surface of the seat ring, and further reduced in diameter and attached to the seal groove. Can not take.

  For this reason, there is a structure shown in FIG. 6 as a seat ring seal structure that is normally considered. That is, the seal mounting portion 3 is provided on the inner diameter surface of the opening 2 of the casing 1. In the same figure, 4 is a ball-shaped valve body, 5 is a seat ring. The seal mounting portion 3 is composed of a step surface 6 and a large diameter portion 7 formed on the inner diameter surface of the opening 2, and a seal member 8 (packing made of expanded graphite) is in contact with the step surface 6 and has a large diameter. Mounted on the part 7.

  Since the sealing member 8 is not self-sealing, a configuration in which the seal pressing member 9 is pressed against the outer end surface and the sealing pressing member 9 is screwed into the inner diameter surface of the opening 2 is employed. A sheet pressing member 10 is screwed into the opening end of the opening 2, and a disc spring 11 is interposed between the sheet pressing member 10 and the sheet ring 5. The seat ring 5 is pressed by the disc spring 11 and pressed against the valve body 4.

In the above-described seal structure, the seal pressing member 9 is operated and the seal member 8 is strongly pushed in, whereby the seal member 8 is slightly elastically deformed, and the pressing force is applied to the inner diameter surface of the opening 2 and the seat ring 5 outside. The seat ring 5 is sealed by acting on both radial surfaces.
JP 2007-16842 A

  In order to increase the use temperature of the ball valve, in order to increase the sealing performance when the sealing structure as described above is used by using the sealing member 8 made of a material that is not self-sealing and has poor elasticity like expanded graphite. It is necessary to press the seal member 8 more strongly through the seal pressing member 9.

  However, when the seal member 8 is pressed, the seal member 8 strongly restrains the seat ring 5 in the radial direction at the same time, so that the smooth movement of the seal ring 5 is hindered. For this reason, in the case of a floating type, the followability with respect to the valve body 4 of the seat ring 5 falls in both the primary side and the secondary side. Thereby, there is a problem that a gap is generated between the valve body 4 and the seat ring 5 and the primary side and secondary side seals are incomplete.

  When the spring force of the disc spring 11 is increased to ensure the sealing, the pressing force of the seat ring 5 against the valve body 4 becomes strong, and the opening / closing torque of the valve body 4 increases, resulting in a disadvantage that the operability is lowered.

  Accordingly, an object of the present invention is to provide a ball valve that has good sealing performance and does not affect operability even when the sealing member has poor elasticity.

  In order to solve the above-described problems, a ball valve according to the present invention is provided with primary side and secondary side openings as shown in FIG. 1 (FIG. 1 is shared with the drawing of Example 1 described later). A casing 24 provided with a valve chamber 23 between 21 and 22, a bonnet 25 for closing the valve chamber 23, and a valve body 26 rotatably supported by the bonnet 25 and housed in the valve chamber 23; The primary side and secondary side seat rings 29, 30 inserted in the primary side and secondary side openings 21, 22 via seal members 27, 28, respectively, and the respective seat rings 29, 30 respectively. Pressing means 33 and 34 are provided to press the primary and secondary ports 31 and 32 of the valve body 26. The valve body 26 is a floating type that is rotatably supported only on the valve shaft 44.

  In the ball valve as described above, in the present invention, the primary and secondary side seal mounting portions 35 and 36 are formed on the outer diameter surfaces of the primary and secondary side seat rings 29 and 30, and the seal mounting portion 35 is provided. 36, the seal members 27, 28 and seal pressing members 37, 38 that press the outer end surfaces of the seal members 27, 28 are fitted, and the pressing members 33, 34 press the seal pressing members 37, 38. This is a configuration.

In the present invention, the “floating type” is a trunnion type in addition to a structure in which the valve body 26 is supported only by the valve shaft 44 and the valve body 26 is displaced by fluid pressure as shown in FIG. In addition, a structure is also included in which the support shaft is fitted into the casing and the valve body can be displaced to some extent by the fluid pressure.
(Function)
The primary side and secondary side seat rings 29 and 30 receive the inward pressing force P1 (see the white arrow in FIG. 2) from the pressing means 33 and 34, respectively, and are pressed against the valve body 26 by this. At the same time, the sealing members 27 and 28 are compressed by the pressing force P1.

  Assuming that the fluid pressure on the primary side is relatively high, the closed valve body 26 is slightly displaced to the secondary side and pressed against the secondary seat ring 30, and the secondary side An outward pressing force P <b> 2 is applied to the seat ring 30. For this reason, the pressing force P1 of the pressing means 34 and the pressing force P2 due to the fluid pressure on the primary side act on the secondary side sealing member 28 from both sides in the compression direction.

  When the seal member 28 is compressed, the inner diameter surface of the seal member 28 is pressed against the seat ring 30, and the outer diameter surface of the seal member 28 is pressed against the inner diameter surface of the opening 22 of the casing 24. Performs sealing of the part. Since the seal member 28 moves integrally with the seat ring 30, the pressing force of the seal member 28 that seals the seat ring 30 does not affect the movement of the seat ring 30.

  Further, since the pressing force P2 due to the fluid pressure is applied to the pressing force for compressing the seal member 28, the pressing force P1 of the pressing means 34 can be set relatively small. For this reason, an increase in the opening / closing torque of the valve body 26 can be suppressed.

  When the fluid pressure on the secondary side is relatively high, the valve element 26 is displaced to the primary side. In this case, the action on the primary side is the same as that described above.

  As described above, according to the present invention, in the floating type ball valve, high sealing performance can be obtained even when a sealing member made of a material having no self-sealing property is used. For this reason, use of a sealing member made of a material having high heat resistance and no self-sealing properties such as expanded graphite enables use at a higher fluid temperature than when a conventional O-ring is used.

  The best mode for carrying out the present invention will be described below based on examples.

  The ball valve of the first embodiment shown in FIGS. 1 to 5 includes a casing 24, a bonnet 25, and a floating valve body 26 supported by the bonnet 25 and housed in the casing 24 as main components. It is a two-way valve. Next, these members will be described in detail.

  A primary side opening 21 and a secondary side opening 22 are provided at both left and right ends of the casing 24, and flanges 40 and 41 for connecting pipes are provided at the respective outer ends. A valve chamber 23 is provided between the inner ends of the openings 21 and 22.

  The valve chamber 23 is closed at the bottom, but the top surface is opened so that the valve body 26 can be inserted into the valve chamber 23. The bonnet 25 is attached to the open part of the upper part of the valve chamber 23 by a bolt 43 through a gasket 42.

  The valve shaft 44 of the valve body 26 penetrates the bonnet 25 and projects upward, and a handle 45 is attached to the projected tip. A gland packing 46 is enclosed around the valve shaft 44 and is pressed by a presser wheel 48 via a packing presser 47.

  The valve body 26 is provided with a valve hole 49 in a direction orthogonal to the valve shaft 44, one end of which is a primary side port 31 and the other end is a secondary side port 32.

  A cylindrical primary side seat ring 29 and a secondary side seat ring 30 are inserted into the inner diameter surfaces of the primary side opening 21 and the secondary side opening 22, respectively, and the inner ends of the seat rings 29, 30 in the valve open state. Is in close contact with the primary and secondary ports 31 and 32 of the valve body 26. When the valve body 26 is rotated 90 degrees, the front ends of the seat rings 29 and 30 are brought into close contact with the closing surface of the valve body 26 to be in a closed state.

  As shown in FIG. 2, the outer diameter surfaces of the seat rings 29 and 30 are different from each other in that the axially inner end side is a large-diameter portion 52 and the outer end side is a small-diameter portion 53 across a right-angled stepped surface 51, respectively. A diameter portion is formed. In the primary side seat ring 29, the primary side seal mounting portion 35 is formed by the step surface 51 and the small diameter portion 53 continuous thereto. Similarly, in the secondary side seat ring 30, the secondary side seal mounting portion 36 is formed by the step surface 51 and the small diameter portion 53 continuous therewith. Further, a smaller-diameter spring receiving surface 54 is provided at the outer end of each small-diameter portion 53.

  Primary and secondary seal members 27 and 28 and corresponding primary and secondary seal pressing members 37 and 38 are mounted on the seal mounting portions 35 and 36, respectively.

  As shown in FIG. 3, the primary side seal member 27 (the reference numerals with parentheses indicate the case of the secondary side seal member 28. The same applies to FIGS. 4 and 5). A matching right inner end surface 55a, an inner diameter surface 55b continuous to the inner diameter side of the inner end surface 55a, an outer diameter surface 55c continuous to the outer diameter side, and these inner and outer diameter surfaces 55b and 55c are inclined at an angle θ. The cross-sectional shape formed by the outer end surface 55d is trapezoidal. The material of the seal members 27 and 28 can be rubber, fluororesin, or the like depending on the operating temperature, but expanded graphite can be used when the temperature is relatively high. The operating temperature of the expanded graphite is −200 to 600 ° C., and can be used in a higher temperature range than the rubber O-ring.

  Further, the seal pressing member 37 (same as the seal pressing member 38) is formed such that the end surfaces of the seal members 27 and 28 facing the outer end surface 55d have the same inclination angle θ, and the outer end surface 55d. Pressed against. The outer end portions of the seal pressing members 37 and 38 are formed to have a length reaching the spring receiving surfaces 54 of the seat rings 29 and 30 (see FIG. 2).

  The primary side pressing means 33 and 34 for pressing the outer end portions of the respective seal pressing members 37 and 38 are constituted by a ring-shaped disc spring 56 and a pressing ring 57, respectively. The disc spring 56 is fitted around the spring receiving surface 54 and is interposed between the seal pressing members 37 and 38 and the pressing ring 57. The retainer ring 57 is screwed to a female screw portion 58 formed on the inner diameter surface of the outer end of each of the openings 21 and 22. By operating the pressing ring 57, the pressing ring 57 can be pressed against the disc spring 56, and a required pressing force can be applied to the seal members 27 and 28 via the seal pressing members 37 and 38.

  In addition, a required gap a is provided between the outer end surfaces of the seat rings 29 and 30 and the pressing ring 57 (see FIG. 2).

  The ball valve according to the first embodiment is configured as described above, and the operation thereof will be described next.

  FIG. 1 shows a valve open state in which the inner ends of the primary and secondary seat rings 29 and 30 are in close contact with the primary side and secondary ports 31 and 32 of the valve body 26. The pressing force of the disc spring 56 reaches the contact portions of the seat rings 29 and 30 with respect to the valve body 26 via the seal pressing members 37 and 38 and the seal members 27 and 28. At the contact portion, the primary side and the secondary side of the pipeline are sealed.

  At the same time, the sealing members 27 and 28 are compressed by the pressing force of the disc spring 56, and the inner diameter surfaces of the openings 21 and 22 and the outer diameter surfaces of the seat rings 29 and 30 are sealed.

  When the valve body 26 is rotated 90 degrees by the operation of the handle 45 from the valve open state, the valve ring is closed, and the inner ends of the seat rings 29 and 30 come into contact with the closing surface of the valve body 26.

  When the fluid pressure on one side, for example, the primary side is higher than the fluid pressure on the secondary side in the valve closed state, the valve is displaced to the secondary side due to the properties of the floating valve body 26. When the displacement occurs, the valve body 26 is pressed against the secondary seat ring 30. At the same time, the primary seat ring 29 moves following the displacement of the valve body 26 by the pressing force of the disc spring 56 of the pressing means 33. For this reason, the primary side seat ring 29 is prevented from separating from the valve body 26.

  In the above case, when the fluid pressure is higher than a certain level, the fluid leaks from the contact surface between the primary side seat ring 29 and the valve body 26 to the valve chamber 23, and the outer diameter of the seal member 28 of the secondary side seat ring 30. The seal on the surface may be broken and leaked to the outside. For this reason, it is necessary to apply a compressive force to the seal member 28 so as to generate a predetermined seal pressure.

  This compressive force is given as the sum of the pressing force P1 (see FIG. 2) by the disc spring 56 of the secondary-side pressing means 34 and the pressing force P2 caused by the fluid pressure opposed thereto. If an attempt is made to apply the same level of compression force only by the disc spring 56, the pressing force P1 of the disc spring 56 increases, and the pressing force of the secondary seat ring 30 against the valve body 26 increases. The opening and closing torque of the motor becomes large and the operability is impaired. However, in the first embodiment, when the same compressive force is applied to the seal member 28, the pressing force P1 of the disc spring 56 may be reduced by the pressing force P2 due to the fluid pressure. The effect on torque is small.

  In contrast to the above case, when the secondary fluid pressure is relatively high, the same action as described above is performed on the primary side.

  Next, the cross-sectional shape of the sealing members 27 and 28 will be described. As shown in FIGS. 2 and 3, since the outer end surface 55d is formed on an inclined surface having an inclination angle θ, when the compressive forces P1 and P2 are applied, the inclined outer end surface 55d becomes the seal retainer. Slip occurs along the inclined surfaces of the members 37 and 38, and the front end portion of the outer end surface 55d and the vicinity thereof bulge to form a seal portion 59 (see the one-dot chain line in FIG. 3). It is pressed and performs an effective sealing action.

  Since the seal portion 59 extends obliquely outward along the inclined outer end surface 55d, effective sealing is performed against fluid flowing toward the valve chamber 23 from the outside.

  Next, modifications of the seal members 27 and 28 will be described with reference to FIGS.

  In the seal member 27 (28) shown in FIG. 4A, the inner end surface 55a is an inclined surface having an inclination angle θ, and the stepped surface 51 in contact with this is also an inclined surface having the same angle. The other three surfaces 55b, 55c, and 55d are surfaces orthogonal to each other. The seal portion 59 extends obliquely inward along the inclined surface as opposed to the case of FIG.

  4B and 4C are configured by a combination of two seal members 27 (28) and 27 (28). In the case of FIG. 4B, the outer end surface 55d of one seal member 27 (28) and the inner end surface 55a of the other seal member 27 (28) in contact therewith are inclined surfaces. The step surface 51 and the end surface 51 'are formed at right angles. In either case, the seal portion 59 is generated at the tip portion of the inclined surface.

  In the case of FIG. 4C, the inner end surface 55a of one seal member 27 (28) is an inclined surface, and the other outer end surface 55d is an inclined surface. The step surface 51 in contact with the inclined surfaces 55a and 55d and the end surface 51 'of the seal pressing member 37 (38) are also inclined surfaces.

  In the modification shown in FIGS. 5A and 5B, the seal member 27 (28) is provided at two positions at a distance in the length direction of the seat ring 29 (30), and the auxiliary seal pressing member is provided between the two. 39 is interposed. As compared with the case where the seal member 27 (28) is provided at one place in the length direction, a more reliable sealing action can be performed.

Sectional view of Example 1 Partially enlarged sectional view of the above Expanded sectional view of the seal part (A)-(c) Sectional drawing of the modification of the seal part same as the above (A) (b) Sectional drawing of the modification of a seal part same as the above Partial sectional view of a conventional example

Explanation of symbols

21 Primary side opening 22 Secondary side opening 23 Valve chamber 24 Casing 25 Bonnet 26 Valve body 27 Primary side sealing member 28 Secondary side sealing member 29 Primary side seat ring 30 Secondary side seat ring 31 Primary side port 32 Secondary Side port 33 Primary side pressing means 34 Secondary side pressing means 35 Primary side seal mounting part 36 Secondary side seal mounting part 37 Primary side seal pressing member 38 Secondary side seal pressing member 39 Auxiliary seal pressing member 40, 41 Flange 42 Gasket 43 Bolt 44 Valve shaft 45 Handle 46 Gland packing 47 Packing retainer 48 Retaining wheel 49 Valve hole 51 Step surface 51 'End surface 52 Large diameter portion 53 Small diameter portion 54 Spring receiving surface 55a Inner end surface 55b Inner diameter surface 55c Outer diameter surface 55d Outer end surface 56 Belleville spring 57 Holding ring 58 Female thread part 59 Sealing part

Claims (6)

  A casing (24) provided with a valve chamber (23) between the primary side and secondary side openings (21, 22), a bonnet (25) for closing the valve chamber (23), and the bonnet (25) The floating type valve element (26) supported by the valve chamber (23) and accommodated in the valve chamber (23), and the primary side and secondary side openings (21, 22) are respectively provided with seal members (27, 28). The inserted primary side and secondary side seat rings (29, 30), and primary side and secondary side pressing means (33, 34) for pressing the seat rings (29, 30) against the valve body (26), respectively. ) Are provided with seal mounting portions (35, 36) on the outer diameter surfaces of the primary and secondary side seat rings (29, 30), and the seal mounting portions (35, 36) are provided with the seal mounting portions (35, 36). The seal members (27, 28) and the outer end surfaces of the seal members (27, 28) are in contact with each other. Le pressing member (37, 38) are respectively fitted, a ball valve wherein the sealing pressing member by the pressing means (33, 34) (37, 38) is characterized in that it has to be pressed.   The outer diameter surfaces of the seat rings (29, 30) are formed with different diameter portions, the inner end side being a large diameter portion (52) and the outer end side being a small diameter portion (53), and the seal mounting portions (35, 36). ) Is formed by a step surface (51) between the large diameter portion (52) and the small diameter portion (53) and the small diameter portion (53) continuous to the step surface (51). Item 2. The ball valve according to Item 1.   An inclined surface having a predetermined inclination angle θ is formed on either one of the surface contacting the step surface (51) of the seal member (27, 28) and the surface on the opposite side, and the inclined surface is formed on the inclined surface. 3. The ball valve according to claim 1 or 2, wherein an inclined surface that matches the inclined surface is formed on an abutting member.   4. The ball valve according to claim 1, wherein a plurality of the sealing members (27, 28) are combined.   The plurality of seal members (27, 28) are constituted by two seal members (27, 28) arranged at a predetermined interval in the length direction of the seat ring (29, 30). The ball valve according to claim 4, wherein an auxiliary seal pressing member (39) is interposed between the members (27, 28).   6. The ball valve according to any one of 1 to 5, wherein the seal member (27, 28) is formed of a non-self-sealing material such as expanded graphite.

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