JP2008175228A - Butterfly valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a butterfly valve having a simple structure which can demonstrate a stable sealing performance by tightening a seat-ring in the amount of appropriate compression, prevent a leak resulting from stress relaxation of the seat-ring, and maintain an improved sealing performance. <P>SOLUTION: In the butterfly valve, a seat ring 40 is held by means of a seat-retainer 45 on a step 36 formed on the inner peripheral side at the end of a cylindrical body 31. A tip end face 46a on the outer peripheral side of the seat retainer 45 is brought into contact with a contact face 37 formed in the step 36. The seat ring 40 is press held by the tip end face 46b on the inner peripheral side of the seat retainer 45 so that the seat retainer 45 is constituted to be held at both ends. In the both-ends-support structure of the seat retainer 45, a specified gap G is provided between the tip end face 46 of the seat retainer 45 and the step 36 to make flexible the tip end face 46 of the seat retainer 45, and the seat retainer 45 and the step 36 are securely fixed by means of a bolt 50 in the region of the gap G. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a butterfly valve, and more particularly, to a seat ring mounting structure in which a seat ring is fixed by bolting via a seat retainer.

  Conventionally, an eccentric butterfly valve having a structure in which the center of the valve stem is eccentric from the center of the valve body is known. As an eccentric butterfly valve, there is a valve called the primary eccentric valve with a structure in which the center of the valve stem is separated from the center of the valve body, in addition to the primary eccentricity, the center of the valve stem is separated from the center line of the valve body. In addition to double eccentricity, a valve called a double eccentric valve, a cone that is tilted from the tube axis direction is cut at both end face positions in the thickness direction of the seat ring that seals with the valve body. There is a butterfly valve called triple eccentric valve with a sealing surface.

  This type of butterfly valve has a mounting structure in which the seat ring is fixed by a seat retainer. Generally, the mounting structure includes a seat ring and a gasket provided on the back side of the seat ring. A seat retainer is put on, a fastening bolt is fastened from above, and the seat ring and the gasket are pressed and fixed.

  As a butterfly valve having such a seat ring mounting structure, for example, there are eccentric valves shown in Patent Document 1 and FIG. For example, in FIG. 7, these eccentric valves are provided with a cylindrical seat surface 1 a on the valve body (valve box) 1 side, and a seat press 3 (sheet retainer) 2 on the seat surface 1 a. The gasket 4 is sandwiched by bolts 5 and held, and the entire seat ring 3 is fixed.

On the other hand, the butterfly valve of Patent Document 2 is provided with a concave stepped portion on the contact surface between the valve main body and the seat ring of the seat pressing member, and the convex stepped portion is engaged with the stepped portion. It has a structure in which a ring or gasket is attached and the sheet is held by fixing with a mounting bolt from above the sheet pressing member (sheet retainer).
The butterfly valve in FIG. 8 has a concave step portion having a shape different from that of Patent Document 2, and a concave step portion 7 is provided only on the valve body (valve box) 6, and a seat is provided on the step portion 7. A ring 9 and a gasket 10 are mounted, and a seat retainer 8 is bolted 5 from above.
For example, in FIG. 8, these valves are attached to the stepped portion 7 by sandwiching the seat ring 9 between the seat retainer 8 and the stepped portion 7 provided in the valve box 6, and fixing the seat retainer 8 with the bolt 5. The seat ring 9 is mounted while being compressed in the tightening direction. In this case, the height dimension L after compression of the seat ring 9 and the gasket 10 is determined by the length from the contact surface 7 a in the stepped portion 7 to the pressing surface 8 a of the seat retainer 8.

  On the other hand, there is a butterfly valve provided with the seat ring mounting structure on the valve body side. For example, as shown in FIG. 9, the seat body has a cylindrical seat surface 11a on the seal side, and this seat surface. There is a butterfly valve 11a in which a seat ring 13 and a gasket 14 are tightened with bolts 15 via a seat retainer 12. Further, as shown in FIG. 10, a concave step portion 16a is formed on the valve body 16 side, a seat ring 18 and a gasket 19 are attached to the step portion 16a, and a seat retainer 17 is tightened with a bolt 15 from above. There is a butterfly valve.

  By the way, this type of butterfly valve is provided with a measure for preventing the bolt from loosening. For example, the eccentric valve disclosed in Patent Document 3 has a mounting bolt as a measure for preventing the dropout when the mounting bolt for tightening the seat retainer is loosened. A snap ring is attached from above. In addition, for the same purpose as the snap ring, there is a butterfly valve in which the bolt is welded after the bolt is tightened.

JP-A-11-148563 Japanese Patent No. 3410682 Japanese Patent No. 3342409

However, in the eccentric valve having the seat mounting structure of Patent Document 1, FIG. 7 and FIG. 9, the thickness dimension of the seat ring and gasket after mounting depends on the bolt tightening amount (tightening torque). This greatly affects the sealing performance of the valve. In other words, since the compression amount of the seat ring and the gasket increases as the bolt tightening amount increases, there is a possibility that these valves may be damaged if tightened excessively. In this case, an appropriate sealing performance is obtained. There was no problem.
As described above, the butterfly valve having a structure in which the entire seat is fastened and fixed as in Patent Document 1, FIG. 7 and FIG. 9 has a low compression amount (crushing allowance) accuracy when compressing the seat ring and the gasket. There is a problem that it is difficult to ensure the amount of compression for exhibiting the sealing performance. For this reason, the sealing performance of these valves was not stable.

  Also, in this type of valve, after tightening the bolt, the seat ring and gasket are tightened between the seat retainer and the valve box (or valve body) to cause a certain distortion (deformation amount) and a certain deformation. A phenomenon occurs in which the stress for maintaining the state gradually decreases. Since the so-called stress relaxation occurs in the seat ring and the gasket, there is a risk that the bolt is loosened and the sealing performance is gradually deteriorated to cause leakage.

  Further, when the compressed state of the seat ring or gasket is extended for a long time, the deformation part of the seat ring or gasket may cause a creep phenomenon to escape into the gap, resulting in stress relaxation and leakage. is there.

  Also, if temperature changes occur repeatedly in the seat ring or gasket and the valve box or seat retainer that holds it, excessive tightening will occur, and the deformation (compression ratio) of the seat ring or gasket will decrease when the temperature returns. As a result, stress relaxation may occur.

In addition, the material of the seat ring and the gasket also affects the occurrence of stress relaxation. For example, the seat ring and the gasket are materials having a smaller coefficient of thermal expansion than the material of the valve box and the seat retainer, such as expanded graphite. In this case, when the temperature of the entire valve changes to the high temperature side, the compression ratio of the seat ring and the gasket decreases. On the other hand, when the temperature of the entire valve changes to the low temperature side, the seat ring and the gasket are excessively tightened, and the compression ratio decreases when the temperature change is eliminated.
On the other hand, if the seat ring or gasket is made of PTFE or other material with a coefficient of thermal expansion greater than that of the valve box (valve body) or seat retainer, the seat ring or gasket will be Over-tightening will occur, and when the temperature change is eliminated, the compression ratio will decrease. On the other hand, when the temperature of the entire valve changes to the low temperature side, the compressibility of the seat ring and gasket decreases.

  Furthermore, when the seat ring or gasket is provided in a laminate structure with different materials such as stainless steel and expanded graphite, the coefficient of thermal expansion of each material is different from each other. In such a case, a gap may be generated between the laminated materials, and the entire material may be distorted, or the materials may be rubbed with each other.

  Also, when temperature changes occur in the seat ring, gasket, valve box, and seat retainer, a temperature difference (thermal expansion difference) occurs in each component, which may cause bolt tightening relaxation. It was.

  On the other hand, the butterfly valve having the seat mounting structure of Patent Document 2 and FIGS. 8 and 10 has a structure in which the accuracy of the compression amount of the seat ring and gasket is ensured because the tightening amount of the bolt is determined by the step size. In addition, since the bolt secures the seat retainer at the position of the step of the valve body, the bolt is less likely to loosen even if stress relaxation occurs in the seat ring or gasket. .

However, even with these butterfly valves, when a creep phenomenon occurs in the seat ring or gasket and stress relaxation occurs, this cannot be dealt with, and there is a risk that the sealing performance will deteriorate and leakage will occur. there were.
In addition, these butterfly valves can avoid over-tightening of the seat ring or gasket by bending the vicinity of the retaining surface of the seat retainer when the seat ring or gasket expands due to temperature changes. When the part contracts and stress relaxation occurs, this cannot be dealt with, and there is a risk of leakage similar to the above.
Furthermore, when the temperature difference (thermal expansion difference) is generated in each component, the bolt tightening relaxation phenomenon due to the thermal expansion difference cannot be prevented, and there is a possibility that leakage may still occur.

  On the other hand, the eccentric valve of Patent Document 3 can prevent the mounting bolts from being loosened or dropped by the snap ring, but the fall-off preventing structure cannot prevent the stress relaxation of the seat ring or the gasket. It was not possible to prevent a decrease in the sealing force due to the occurrence of. The same applies to the case where the welding is stopped after the bolt is tightened, and the reduction in the sealing force due to the stress relaxation cannot be prevented. Furthermore, this eccentric valve has a disadvantage in that the structure becomes complicated and the labor for maintenance and the like increases.

  The present invention has been developed as a result of diligent research in view of the above circumstances, and the object of the present invention is to provide a stable sealing property by tightening the seat ring with an appropriate compression amount. An object of the present invention is to provide a butterfly valve having a simple structure that can prevent leakage due to stress relaxation and maintain high sealing performance.

  In order to achieve the above object, the invention according to claim 1 is configured such that a seat ring is held via a seat retainer on a step formed on the inner peripheral side of an end portion of a cylindrical body, and an outer peripheral end surface of the seat retainer is provided. The seat retainer is brought into contact with the abutting surface formed on the stepped portion, and the seat ring is pressed and held at the inner peripheral side front end surface of the seat retainer to provide a double-support structure for the seat retainer. This is a butterfly valve in which a predetermined gap is provided between the leading end surface and the stepped portion to make the leading end surface of the seat retainer a flexible surface, and the seat retainer and the stepped portion are fixed via a bolt in the gap region.

  The invention according to claim 2 is the butterfly valve in which a part of the stepped portion or a part of the seat retainer is protruded between the gaps to narrow the gap.

  The invention according to claim 3 is a butterfly valve in which a gasket is interposed on one side surface or both side surfaces of the seat ring.

  According to a fourth aspect of the present invention, a valve body rotatably supported through a valve rod is provided in the body, the valve body is decentered from the rotation axis of the valve rod by a certain distance, and the flow direction An elliptical sealing surface is formed by an outer peripheral surface of a cone having a center inclined from the center of the flow path, and is disposed at a position decentered from the center of the flow path, and this sealing surface is used as an inner peripheral sealing surface of the seat ring. This is a butterfly valve that exhibits a triple eccentric structure that is tightly sealed to each other.

  The invention according to claim 5 is the abutting surface in which the seat ring is held via the seat retainer on the stepped portion formed on the outer peripheral side of the end of the valve body, and the inner peripheral side front end surface of the seat retainer is formed on the stepped portion. The sheet retainer is pressed and held at the outer peripheral end surface of the seat retainer to form a double-support structure for the seat retainer, and this double-support structure for the seat retainer provides a space between the front surface of the seat retainer and the stepped portion. A butterfly valve in which a predetermined gap is provided to make the front end surface of the seat retainer a flexible surface, and the seat retainer and the stepped portion are fixed to each other via a bolt in the gap region.

  According to the first aspect of the present invention, when the seat ring is tightened with the bolt via the seat retainer, the accuracy of the compression amount of the seat ring does not depend on the tightening torque of the bolt, and the step is provided on the body. This is a butterfly valve that can be stably tightened because it is determined and tightened with an appropriate amount of compression. Moreover, since the seat ring is pressed by the seat retainer and the bolt so as to be compressed against the abutting surface of the body, the seat retainer generates a slight deflection like a disc spring, and this deflection causes the bolt tightening axial force. It can be stored as an elastic force to prevent leakage against stress relaxation and maintain high sealing performance over a long period of time while exhibiting excellent durability. In addition, the seat retainer's deflection provides durability against the stress relaxation of the seat ring and prevents the bolts from loosening, with a simple structure without requiring a new bolt drop-off structure. It is a butterfly valve that can be formed.

  According to the second aspect of the present invention, since the gap between the front surface of the seat retainer and the stepped portion is narrowed, it is possible to suppress the fluid from staying in the gap, and the deterioration and the stay of each component due to the fluid. It is a butterfly valve that can prevent the spoilage of the damaged fluid.

  According to the invention which concerns on Claim 3, when a gasket is distribute | arranged to the side surface of a seat ring, it is a butterfly valve which can prevent the leak by stress relaxation of a gasket and can exhibit high sealing performance.

  The invention according to claim 4 is a butterfly valve that can be applied to a butterfly valve with a triple eccentric structure excellent in sealing performance and functionality, and can further enhance the function of the butterfly valve with a triple eccentric structure. .

  According to the fifth aspect of the present invention, the seat ring can be attached to the valve body as in the case of being attached to the body. At this time, as in the case of being attached to the body, an appropriate amount of compression of the seat ring is provided. This is a butterfly valve that can exhibit a stable sealing performance, can prevent leakage due to stress relaxation of the seat ring, maintain a high sealing performance, and can prevent bolts from loosening.

Hereinafter, preferred embodiments and operations of a butterfly valve according to the present invention will be described in detail with reference to the drawings. In the present embodiment, an example applied to a triple eccentric butterfly valve will be described.
1 to 3 show a first embodiment of a butterfly valve of the present invention.
In the triple eccentric butterfly valve shown in the figure, a body (valve box) 31 of the valve body 30 is formed in a cylindrical shape and has a flow path 31a therein, and a valve rod 32 is provided in the body 31. The valve body 33 is pivotally supported rotatably. The valve body 33 is provided so as to be operated in an open or closed state by rotating the valve rod 32 by 90 °. A pipe 35 having mounting flanges 35a is provided on both sides of the body 31 so as to be attachable. The pipe 35 is attached by fixing a fixing bolt (not shown) to the bolt hole 35b with the body 31 in between. It is done. In this example, for the sake of convenience, the direction of the flow path of the valve body 30 is that the valve rod 32 mounting side of the valve body 33 is the primary side, and the other side sandwiching the valve body 33 is the secondary side. The secondary side can also be used in the opposite direction.

  A gasket 35 c is mounted between the side surface of the body 31 and the mounting flange 35 a of the pipe 35. The gasket 35c is formed so as to avoid the fitting portion between the seat retainer 45 and the mounting groove 38 and the bolt mounting hole 47 of the seat retainer 45 in order to ensure the sealing performance between the body 31 and the pipe 35. It is arranged on the outer peripheral side.

  A step portion 36 to which the seat ring 40 can be mounted is provided on the inner peripheral side of the end portion of the body 31, and an annular abutting surface 37 for abutting the seat retainer 45 is provided on the outer peripheral side of the step portion 36. Forming. Further, a seat surface 36a with which the seat ring 40 abuts is formed on the inner peripheral side of the stepped portion 36, and a bolt hole 36b for attaching the bolt 50 is formed in the seat surface 36a. Further, an attachment groove 38 for mounting the seat retainer 45 is provided on the end side of the step portion 36. The sheet retainer 45 is formed in an annular shape from a metal such as stainless steel.

  The seat ring 40 is made of a metal such as stainless steel such as SUS316 or SUS316L. In addition to this, the material of the seat ring 40 may be, for example, a laminate structure in which a metal such as stainless steel and a heat-resistant non-metallic elastic body are laminated. In this case, as a plate of the heat-resistant non-metallic elastic body, For example, there is one mainly composed of expanded graphite (graphite). Further, as the seat ring 40, a resin such as PTFE containing a mixed material such as graphite may be used.

  Although not shown, the seat ring 40 is formed so that its inner peripheral seal surface 41 is elliptical when viewed from the flow path direction. Further, the inner peripheral seal surface 41 is formed as a flow path as shown in FIG. It is provided in a substantially conical shape whose primary side is enlarged in diameter with respect to the direction. The outer diameter side of the seat ring 40 is provided in a circular shape (not shown), and after the seat ring 40 is inserted into the step portion 36, the outer peripheral side can be uniformly tightened with the retainer bolt 50 via the seat retainer 45. Provided.

The gasket 39 is made of, for example, expanded graphite or a metal such as stainless steel as a core metal, and the core metal is covered with expanded graphite, or the whole is made of a resin such as PTFE, and one side surface of the seat ring 40 or It is interposed on both sides. In the present embodiment, a gasket 39 is mounted on the primary side of the valve body 30 to seal between the seat ring 40 and the body 31. In this way, in FIG. 3, the leakage path when the valve is closed is blocked, and the flow f _{1 in} which the fluid leaks to the secondary side via the space between the seat ring 40 and the body 31 is prevented. The gasket 39 can be omitted, and only the seat ring 40 can be attached.

  The seat ring 40 and the gasket 39 are held on the seating surface 36 a of the step portion 36 via the seat retainer 45. Here, in the seat retainer 45, the side surface on the valve body 33 side is referred to as a front end surface 46, and the side surface on the piping 35 side is referred to as a rear end surface 45a. When the seat ring 40 and the gasket 39 are mounted, the seat ring 40 is brought into contact with the inner peripheral front end surface 46b of the seat retainer 45 in a state where the outer peripheral end surface 46a of the seat retainer 45 is in contact with the abutting surface 37. The gasket 39 is pressed and held. Accordingly, the outer periphery of the seat retainer 45 is supported by the step portion 36 of the body 31, while the inner periphery presses the seat ring 40 and the gasket 39 toward the body 31. As described above, the seat retainer 45 is disposed on the side portion of the body 31 by the dual support structure in which the outer peripheral side and the inner peripheral side are supported.

With this support structure, a predetermined gap G is formed between the front end surface 46 of the seat retainer 45 and the stepped portion 36 (seat surface 36a), and the front end surface 46 of the seat retainer 45 serves as a flexible surface. The step portion 36 is fixed in the region of the gap G via the bolt 50.
Note that the height (height dimension of the gap G) T of the stepped portion 36 is set to a dimension that allows a predetermined compressive force to be applied when the seat ring 40 and the gasket 39 are tightened with the bolts 50.

As shown in FIG. 1, the valve body 33 is provided such that the rotation axis O ₁ of the valve rod 32 is eccentric from the center of the valve body 13 (seal position with the seat ring 20) by a certain distance, and The rotational axis O ₁ is arranged at a position decentered from the center line O ₂ of the body 31 flow path by a certain distance, and is further elliptical by the outer peripheral surface of the cone E having the center line O ₃ inclined from the center line O _2. The sealing surface 34 is formed. The seal surface 34 is provided on the inner peripheral seal surface 41 of the seat ring 40 fixed to the body 31 so as to be sealable. The valve body 33 is rotatably supported via the valve rod 32, and when the valve body 33 is rotated in the closing direction, the seal surface 34 is not slid by the triple eccentric structure and the inner peripheral seal surface 41 is slid. Can be tightly sealed. As a result, when the valve element 33 is operated, excellent durability can be exerted without adversely affecting the operation torque, and the valve element 33 operates smoothly at the time of opening and closing, thereby providing high sealing performance by the torque seal function. We are trying to secure it.

Next, the operation of the butterfly valve configured as described above will be described.
In FIG. 3, the gasket 39 and the seat ring 40 are mounted on the seat surface 36 a of the body 31, the seat retainer 45 is mounted from above, and the seat retainer 45 is tightened with the bolt 50. When the seat ring 40 and the gasket 39 are compressed by tightening the bolt 50, the thickness of the seat ring 40 and the gasket 39 is reduced, and the outer peripheral end surface 46a of the seat retainer 45 abuts against the abutting surface 37 of the step portion 36. The accuracy of the basic compression amount when the seat ring 40 and the gasket 39 are compressed and held is determined by the height T of the step portion. As a result, the tightening accuracy of the bolt 50 is ensured, the accuracy of the compression amount of the seat ring 40 and the gasket 39 is kept high, and a predetermined compression amount is always ensured to obtain a stable sealing performance.

  The seat retainer 45 is disposed on the side portion of the valve body 30 by a both-end support structure, with the outer peripheral end surface 46a supported by the step portion 36 and the inner peripheral end surface 46b supported by the seat ring 40 (gasket 39). Yes. Therefore, when the bolt 50 is further tightened from this state, as shown by the broken line in FIG. 3, the seat retainer 45 generates a slight deflection δ like a disc spring due to its elasticity, and the tightening axial force of the bolt 50 is the seat retainer. Is stored as an elastic force by the deflection δ.

  With the tightening force of the bolt 50, a reaction force (restoring force) based on the deflection δ of the seat retainer 45 is applied, making it difficult to tighten. Accordingly, when the bolt 50 is tightened, excessive tightening of the bolt 50 can be prevented, and the bolt 50 can be tightened with an appropriate tightening force. At this time, even when an error in the thickness of the seat ring 40 or the gasket 39 occurs, an appropriate tightening force can be exerted and tightened in an appropriate state while absorbing this error.

  In the seat retainer 45, if the tightening portion of the bolt 50 is a force point, the contact portion with the step portion 36 is a fulcrum, and the contact portion with the seat ring 40 is an action point, the elastic force accumulated by tightening the bolt 50 is the lever. Based on the principle, the pressure is converted into a pressing force (not shown) that presses the seat ring 40 and the gasket 39. This pressing force is set by adjusting the tightening force of the bolt 50 so as to give a prescribed large compression amount to the seat ring 40 and the gasket 39.

Thus, by providing the structure that presses the seat ring 40 (gasket 39) using the elastic force (accumulation force) of the seat retainer 45, the bolt 50 is loosened even if stress relaxation occurs. Can be prevented.
Moreover, the tension | tensile_strength of the axial direction to the extraction direction always arises in the volt | bolt 50 by applying the above reaction force. Therefore, the fastening force (frictional force) between the bolt 50 and the body 31 is strengthened, and it is possible to prevent the bolt 50 from being loosened or dropped out naturally without newly providing a drop-off preventing structure. Even when stress relaxation occurs, this axial force can be maintained, and as a result, the sealing performance of the seat ring 40 and the gasket 39 can be maintained.

  When the creep phenomenon of the seat ring 40 or the gasket 39 occurs, the force of pressing the seat ring 40 or the gasket 39 can be supplemented by the accumulated force of the seat retainer 45, and the sealing force by the seat ring 40 or the gasket 39 is increased. Can be maintained.

  In addition, even if excessive tightening occurs due to repeated temperature differences in the valve body 30, it can be mitigated by the stored force of the seat retainer 45, and even when the temperature difference returns, The force in the tightening direction can be supplemented. In addition, it is possible to eliminate the decrease in the compression rate after the temperature change caused by the difference in thermal expansion coefficient between the seat ring 40 and the gasket 39.

  In addition, when the temperature difference is generated in the valve body 30, even if tightening relaxation occurs due to the thermal expansion difference of the seat ring 40 or the gasket 39, an appropriate tightening force can be maintained by the stored force of the seat retainer 45.

  The seat ring 40 and the gasket 39 have an appropriate degree of freedom in the circumferential direction due to the gap G provided on the outer peripheral side by the step portion 36. As a result, when the seat retainer 45 is pressed or when the valve body 33 is sealed, the seat ring 40 and the gasket 39 have a self-aligning function, and the inner peripheral seal surface 41 is automatically brought into an appropriate state with respect to the flow path. Can keep.

In FIG. 4, 2nd Embodiment of the butterfly valve of this invention is shown. In this embodiment, the same parts as those in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted. Here, as shown in the above embodiment, the gasket 35c is because it is disposed on the outer peripheral side of the sheet retainer 45, in the valve of FIG. 3, the valve by the path of f ₂ and f ₃ fluid flows two There is a possibility of entering the gap G from the next side (the gap between the rear end surface 45a of the seat retainer 45 and the mounting flange 35b).

Therefore, in the second embodiment, in the gap region, a part of the stepped portion 48 protrudes toward the inner diameter side to provide a protruding portion 48a, and the protruding portion 48a makes the gap G narrower than in the first embodiment. and was a gap G _1, is obtained to be able to suppress stagnation of the fluid which has entered the gap region. The height T ₁ of the up surface 37 abutment from projection part 48a at this time, when loaded with a predetermined compressive force to the seat ring 40 and the gasket 39, slightly than the amount of deflection (not shown) occurs on the sheet retainer 45 It is necessary to set it to be a large size. The height _{T 1,} for example, in the case of the valve of the valve nominal diameter 150A, may be set to about 1 to 2 mm.
Incidentally, as this in the embodiment, but by projecting a part of the stepped portion 48 side to narrow the gap G _1, to narrow the gap and protrude form part of the sheet retainer 45 to the gap side It may be (not shown). Also in this case, the same effect as the case where the stepped portion 48 side is provided can be exhibited.

FIG. 5 shows a third embodiment of the butterfly valve of the present invention.
In this embodiment, a stepped portion 52 is formed on the outer peripheral side of the end of the valve body 51, and a seat ring 57 and a gasket 58 are held on the stepped portion 52 by a seat retainer 55. In this case, the inner peripheral end surface 56a of the front end surface 56 of the seat retainer 55 is brought into contact with the abutting surface 53 formed on the stepped portion 52, while the seat ring 57 (gasket) is formed on the outer peripheral end surface 56b of the seat retainer 55. 58), the seat retainer 55 has a both-end support structure. As described above, the seat ring 57 (gasket 58) can be attached to the valve body 51 by the same mounting structure as that for mounting on the body 31 in the above-described embodiment. gap with, a seat retainer 55 and the step portion 52 and the distal end surface 56 of the deflection surface of the sheet retainer 55 with a predetermined gap G ₂ between the front end surface 56 and the stepped portion 52 of the likewise sheet retainer 55 and it is possible to fix through the bolt 50 in the area of G _2.

Furthermore, in FIG. 6, 4th Embodiment of the butterfly valve of this invention is shown. In this embodiment, the same parts as those of the third embodiment are denoted by the same reference numerals, and the description thereof is omitted. In this embodiment, a valve body 58 is provided in which a part of the stepped portion 59 protrudes from the butterfly valve of the third embodiment to the outer peripheral side in the gap region, and a protruding portion 59a is provided. G ₃ is narrowed. Thus, even when mounting the seat ring in the valve body side, the embodiment and can narrow the gap in the same manner, it is possible to suppress stagnation of the fluid which has entered into the gap G _3. In addition, in this case as well, a part of the seat retainer 55 can be protruded to the gap side (not shown) as described above.

  The present invention can be applied to a butterfly valve having a structure other than the triple eccentric structure described in the above embodiment, and can be easily applied to a normal butterfly valve having no eccentric structure as well as a primary eccentric type and a double eccentric type butterfly valve. Of course, it can be applied to.

It is sectional drawing which showed 1st Embodiment of the butterfly valve in this invention. It is the principal part enlarged view which showed the body vicinity of FIG. FIG. 3 is a partially enlarged cross-sectional view showing a main part of FIG. 2. It is principal part sectional drawing which showed 2nd Embodiment of the butterfly valve of this invention. It is principal part sectional drawing which showed 3rd Embodiment of the butterfly valve of this invention. It is principal part sectional drawing which showed 4th Embodiment of the butterfly valve of this invention. It is principal part sectional drawing which showed the 1st example of the conventional butterfly valve. It is principal part sectional drawing which showed the 2nd example of the conventional butterfly valve. It is principal part sectional drawing which showed the 3rd example of the conventional butterfly valve. It is principal part sectional drawing which showed the 4th example of the conventional butterfly valve.

Explanation of symbols

30 Valve body 31 Body 32 Valve rod 33 Valve body 34 Seal surface 36 Step portion 37 Abutting surface 39 Gasket 40 Seat ring 41 Inner peripheral seal surface 45 Sheet retainer 46 Front end surface 46a Outer peripheral side front end surface 46b Inner peripheral side front end surface 50 Bolt G gap

Claims (5)

  The seat ring is held on the step formed on the inner peripheral side of the end of the cylindrical body via the seat retainer, and the outer peripheral side front end surface of the seat retainer is brought into contact with the abutting surface formed on the step. The seat ring is pressed and held at the inner peripheral end surface of the seat retainer to form a double-sided support structure for the seat retainer, and the double-supported support structure for the seat retainer provides a space between the front end surface of the seat retainer and the stepped portion. The butterfly valve is characterized in that a predetermined gap is provided to make the front end surface of the seat retainer a flexible surface, and the seat retainer and the stepped portion are fixed to each other through a bolt in the gap region.   The butterfly valve according to claim 1, wherein a part of a stepped portion or a part of a seat retainer is protruded between the gaps to narrow the gap.   The butterfly valve according to claim 1 or 2, wherein a gasket is interposed on one side surface or both side surfaces of the seat ring.   A valve body rotatably supported via a valve rod is provided in the body, and the valve body is decentered from the rotation axis of the valve rod by a certain distance and decentered by a certain distance from the center in the flow path direction. An elliptical sealing surface is formed by an outer peripheral surface of a cone having a center inclined from the center of the flow path, and the sealing surface is tightly sealed to the inner peripheral sealing surface of the seat ring. The butterfly valve according to any one of claims 1 to 3, which exhibits a triple eccentric structure as described above.   A seat ring is held via a seat retainer on a step formed on the outer peripheral side of the end of the valve body, and an inner peripheral side front end surface of the seat retainer is brought into contact with a contact surface formed on the step, and the seat The seat ring is pressed and held at the outer peripheral end surface of the retainer to form a double-support structure for the seat retainer, and the double-support structure for the seat retainer allows a predetermined distance between the front surface of the seat retainer and the stepped portion. The butterfly valve is characterized in that the seat retainer and the stepped portion are fixed to each other through a bolt in the gap region.

Images