butterfly valve
By creating a gap between the bearing bore and the bushing of the butterfly valve and setting an inward recess, the stress concentration problem caused by the bending moment of the valve shaft due to fluid pressure is solved, preventing damage to the bearing bore and fluid leakage, and improving the corrosion resistance and sealing performance of the butterfly valve.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ASAHI YUKIZAI KOGYO CO LTD
- Filing Date
- 2021-07-29
- Publication Date
- 2026-06-23
AI Technical Summary
In butterfly valves that handle corrosive fluids, the bending moment of the valve shaft caused by fluid pressure leads to stress concentration around the bearing bore opening, which is prone to damage, and wear of the sealing parts leads to fluid leakage.
A gap is formed between the bearing bore and the bushing of the butterfly valve, and an annular inward portion is provided in the adjacent area to avoid direct contact between the inner circumferential surface of the bearing bore and the outer circumferential surface of the bushing. The area around the bearing bore is reinforced by an insert to prevent force transmission.
It effectively prevents damage to the resin material at the opening of the bearing hole in the valve body, improves sealing performance, and avoids fluid leakage and stress concentration.
Smart Images
Figure CN116113784B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a butterfly valve having a valve body with a core material covered by a resin material. Background Technology
[0002] In applications involving the handling of corrosive fluids, butterfly valves are known to be used to balance corrosion resistance and strength. These valves have a core material (insert) made of a synthetic resin material with excellent corrosion and chemical resistance. Such a butterfly valve is configured such that a valve shaft, which is rotatably supported in a bearing bore in the valve body, passes through a seat ring installed in the inner circumferential surface of the internal flow path. This seat ring is non-rotatably connected to the valve shaft bore in the valve body, and the valve body rotatably supports the valve body within the internal flow path. Furthermore, the butterfly valve has a sealing portion between the valve shaft hole on the outer periphery of the valve body and the through hole on the valve seat surface of the seat ring, a sealing portion caused by the contact between the outer peripheral surface of the valve shaft and the inner peripheral surface of the through hole of the seat ring, and a plurality of stepped sealing portions such as the sealing portion between the outer peripheral surface of the valve shaft and the bearing hole and the inner peripheral surface of the valve shaft hole, so that the fluid in the internal flow path will not leak into the valve shaft hole of the valve body or the bearing hole of the valve body.
[0003] In a butterfly valve, when the valve is closed, the pressure of the fluid in the internal flow path acts on the valve body, pushing it towards the secondary side (downstream side). This causes the valve shaft connected to the valve body to move towards the secondary side. On the other hand, the bearing bore of the valve body, to absorb machining errors of the valve shaft or bearing bore, or to prevent wear on the valve shaft, is generally formed with an inner diameter slightly larger than the outer diameter of the valve shaft, creating a gap between the inner circumferential surface of the bearing bore and the outer circumferential surface of the valve shaft. Therefore, when fluid pressure acts on the valve body, the valve shaft moves towards the secondary side along with the valve body by the same amount as this gap. Accompanying this movement of the valve shaft, the through hole of the seat ring also deforms, leading to a problem of fluid leakage from the created gap. Furthermore, there is a problem of difficulty in sealing between the outer circumferential surface of the rotating valve shaft and the inner circumferential surfaces of the bearing bore and through hole of the stationary valve body.
[0004] To address this problem, a butterfly valve has been proposed, as described in, for example, Patent Document 1 or Patent Document 2. A bushing extending from the bearing hole of the valve body to the valve shaft hole of the valve body is inserted into the outside of the valve shaft in a rotatable manner. The valve shaft is supported rotatably in the bearing hole and the valve shaft hole through the bushing, while sealing members such as O-rings are provided on the outer peripheral surface of the bushing. This seals the outer peripheral surface of the valve shaft with the bearing hole of the valve body, the valve shaft of the seat ring, and the inner peripheral surface of the valve shaft hole of the valve body.
[0005] [Prior art literature]
[0006] [Patent Literature]
[0007] [Patent Document 1] Japanese Patent Application Publication No. 60-1475
[0008] [Patent Document 2] Japanese Patent Application Publication No. 9-303575 Summary of the Invention
[0009] [The problem the invention aims to solve]
[0010] As described above, when a butterfly valve with a valve body formed by coating a metal core with synthetic resin and supporting the valve shaft in a bearing bore and valve shaft bore through a bushing is used in piping lines for corrosive liquids, it is considered that the bending moment of the valve shaft caused by the fluid pressure acting on the valve body when the valve is closed is supported by the bearing bore of the valve body through the bushing. Therefore, a metal insert may be placed around the bearing bore for reinforcement. In this case, when the seal around the valve shaft wears down due to the handling of corrosive liquids, and the seal between the outer periphery of the valve body and the valve seat surface of the seat ring breaks, it is preferable that the liquid leaking from the internal flow path into the bearing bore will not come into contact with the metal insert of the valve body. In other words, it is preferable that the insert is completely covered with synthetic resin, and the insert is not exposed to the outside. For this reason, the insert must not be placed around the opening on the internal flow path side of the bearing bore, and the opening of the bearing bore must be formed only by synthetic resin material. If it is constructed in this way, then the area around the opening of the bearing hole in the valve body will not have any reinforcing inserts.
[0011] On the other hand, if the valve body is pushed to the secondary side by the fluid pressure acting when the valve is closed, a bending moment is generated on the valve shaft connected to the valve body. If this bending moment is to be supported through the bearing bore via the bushing, stress concentration occurs around the opening of the bearing bore in the valve body. However, since no reinforcing inserts are provided around the opening of the bearing bore, the bending moment generated on the valve shaft must be borne solely by the synthetic resin material. As a result, if the pressure from the fluid acting on the valve body is high when the valve is closed, the area around the opening of the bearing bore in the valve body becomes prone to damage.
[0012] Therefore, the object of the present invention is to solve the problems existing in the prior art and to provide a butterfly valve that prevents the force caused by the bending moment of the valve shaft due to the fluid pressure acting on the valve body when the valve is closed from being transmitted through the bushing to the area around the opening on the internal flow path side of the valve shaft hole, thereby suppressing damage to the valve body.
[0013] [Technical means to solve the problem]
[0014] In view of the above objectives, the present invention provides a butterfly valve comprising: a valve body, at least one surface of which is made of resin material and has an internal flow path formed therein; a valve shaft supported rotatably on the valve body; a valve body connected to the valve shaft and supported rotatably on the valve body, and disposed within the internal flow path; and a bushing inserted outside the valve shaft, wherein a bearing hole is provided in the valve body, the bearing hole supports the valve shaft rotatably through the bushing, the bearing hole has an opening facing the internal flow path, and the bearing hole and the bushing have a shape in which a gap is formed between the inner peripheral surface of the bearing hole and the outer peripheral surface of the bushing in the region adjacent to the opening.
[0015] In the aforementioned butterfly valve, the valve shaft connected to the valve body is supported rotatably by a bearing hole in the valve body via a bushing. A gap is formed between the inner circumferential surface of the bearing hole and the outer circumferential surface of the bushing in the region adjacent to the opening of the bearing hole facing the internal flow path. When the butterfly valve is closed, fluid pressure acts on the valve body, causing it to move towards the secondary side (downstream). This generates a bending moment on the valve shaft. When the inner circumferential surface of the bearing hole contacts the outer circumferential surface of the bushing, the bending moment of the valve shaft is supported by the valve shaft hole through the bushing. The force caused by the bending moment is transmitted through the bushing to the inner circumferential surface of the bearing hole, resulting in stress concentration, particularly at the opening of the bearing hole. Therefore, if at least one surface of the valve body is made of resin material, the resin material portion around the opening becomes susceptible to damage due to stress concentration caused by the fluid pressure experienced by the valve body when the valve is closed. However, in the butterfly valve according to the present invention, a gap is formed between the inner circumferential surface of the bearing hole and the outer circumferential surface of the bushing in the region adjacent to the opening. Therefore, even when the valve is closed, the fluid pressure acts on the valve body, and the valve shaft connected to the valve body generates a bending moment. In the area adjacent to the opening of the bearing hole, the gap between the inner circumferential surface of the bearing hole and the outer circumferential surface of the bushing becomes a buffer space, which avoids the contact between the outer circumferential surface of the bushing and the inner circumferential surface of the bearing hole, and can prevent the transmission of force from the outer circumferential surface of the bushing to the inner circumferential surface of the bearing hole.
[0016] In the aforementioned butterfly valve, the bushing has an annular recessed portion on its outer periphery adjacent to the opening, and the gap between the inner circumferential surface of the bearing bore and the outer circumferential surface of the bushing is preferably formed by the recessed portion. In this case, with the valve shaft extending along the rotation axis of the valve body, the valve body further includes a cylindrical insert for reinforcing the valve body. The insert is preferably configured to be separate from the bearing bore and surround the bearing bore, and extends in the direction of the rotation axis to at least surround a portion of the outer side of the recessed portion.
[0017] In the aforementioned butterfly valve, it is preferable that the gap includes a conical portion adjacent to the opening, and that the conical portion is formed such that the gap between the inner circumferential surface of the bearing hole and the outer circumferential surface of the bushing is larger as it gets closer to the opening.
[0018] [Comparison with the efficacy of existing technologies]
[0019] According to the present invention, the butterfly valve is configured such that a valve shaft fixed to the valve body is rotatably supported by a bearing bore in the valve body through a valve bushing. In the region adjacent to the opening of the bearing bore facing the internal flow path, a gap is formed between the inner circumferential surface of the bearing bore and the outer circumferential surface of the bushing. Therefore, even when fluid pressure acts on the valve body during valve closure, and the valve shaft connected to the valve body generates a bending moment, the gap between the inner circumferential surface of the bearing bore and the outer circumferential surface of the bushing in the region adjacent to the opening of the bearing bore acts as a buffer space, preventing contact between the outer circumferential surface of the bushing and the inner circumferential surface of the bearing bore, and thus preventing the transmission of force from the outer circumferential surface of the bushing to the inner circumferential surface of the bearing bore. As a result, the butterfly valve achieves the effect of suppressing damage to the resin material portion near the opening of the bearing bore in the valve body. Attached Figure Description
[0020] Figure 1 This is a longitudinal cross-sectional view of the butterfly valve according to the present invention in the closed state, viewed along the axis of the self-flow path.
[0021] Figure 2 It is a display Figure 1 The diagram shows a partial three-dimensional cross-sectional view of the butterfly valve body.
[0022] Figure 3 It is a display Figure 1 A partial three-dimensional cross-sectional view of the bearing portion of the valve body that supports the valve shaft of the butterfly valve shown.
[0023] Figure 4 It is a display that will Figure 3 The enlarged cross-sectional view of the bearing portion of the valve body shown is displayed near the opening.
[0024] Figure 5 This is a partially enlarged cross-sectional view of a modified example of the bearing portion of the valve body.
[0025] Figure 6 It is a display that will Figure 5 The enlarged cross-sectional view of the area near the opening of the modified bearing portion shown is shown.
[0026] Figure 7 Is it displayed with Figure 1 For a vertical cross section, Figure 1 The enlarged cross-sectional view shown is of a portion near the opening of the valve shaft hole used to connect the valve shaft to the valve body of the butterfly valve.
[0027] Figure 8 It is a display Figure 1 The diagram shows a side view of the valve shaft of the butterfly valve. Detailed Implementation
[0028] Hereinafter, embodiments of the butterfly valve 11 according to the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments.
[0029] First refer to Figure 1 and Figure 2 This explains the overall structure of the butterfly valve 11. Figure 1 This is a longitudinal cross-sectional view of the butterfly valve along the axis of the gravity flow path, showing its closed state. Also... Figure 2 To show Figure 1 The diagram shows a partial three-dimensional cross-sectional view of the butterfly valve body, cut open to reveal its cross-section.
[0030] The butterfly valve 11 includes a valve body 13 that is generally hollow cylindrical and has an internal flow path 13a extending along the flow path axis therein, a valve shaft 15 that is rotatably supported on the valve body 13, a seat ring 17 that is annular and mounted on the inner circumferential surface of the internal flow path 13a, a valve body 19 that is disposed in the internal flow path 13a and connected to the valve shaft 15 and is supported on the valve body 13 in a manner that allows it to rotate about the rotation axis R, and a bushing 21 made of synthetic resin material that is rotatably inserted into the outside of the valve shaft 15. The valve body 19 can be opened and closed by connecting or separating the valve seat portion 17d formed on the inner circumferential surface of the seat ring 17 from the outer circumferential edge of the valve body 19.
[0031] In the butterfly valve 11 shown in the figure, the valve shaft 15 is arranged along the rotation axis R. Figure 1 The valve body 19 is constructed by a first valve shaft 15a on the upper side and a second valve shaft 15b on the lower side of the figure. The bushing 21 is also constructed by a first bushing 21a inserted rotatably outside the first valve shaft 15a and a second bushing 21b inserted rotatably outside the second valve shaft 15b. The valve body 19 is rotatably supported on the valve body 13 by the first valve shaft 15a and the second valve shaft 15b respectively through the first bushing 21a and the second bushing 21b. A drive unit (not shown in the figure) is connected to the first valve shaft 15a. By using the drive unit to rotate the first valve shaft 15a, the valve body 19 rotates around the rotation axis R to open and close the valve. In the embodiment shown in the figure, the valve shaft 15 is constructed by two valve shafts 15, namely the first valve shaft 15a and the second valve shaft 15b. However, the first valve shaft 15a and the second valve shaft 15b can also be formed as a single valve shaft 15. Similarly, the first bushing 21a and the second bushing 21b can be formed as a single bushing 21. The first valve shaft 15a and the second valve shaft 15b can be made of metal materials such as cast iron, steel, carbon steel, copper, copper alloy, brass, stainless steel, aluminum and titanium, but there are no particular limitations as long as the materials do not pose a problem in terms of strength.
[0032] The valve body 13 is formed of a synthetic resin material. As a synthetic resin material, materials such as polyvinyl chloride (PVC), polypropylene (PP), polyvinylidene fluoride (PVDF), polyethylene (PE), polyphenylene sulfide (PPS), polydicyclopentadiene (PDCPD), polytetrafluoroethylene (PTFE), acrylonitrile butadiene styrene resin (ABS resin), chlorinated polyvinyl chloride (PVC-C), perfluoroalkoxyalkane (PFA), polydicyclopentadiene (PDCPD), fiber-reinforced plastic (FRP), and other synthetic resin materials, as well as those reinforced with glass fiber, are suitable. The upper part of the valve body 13 is provided with a generally disc-shaped top flange 23. The valve body 13 also has a first bearing hole 25 and a second bearing hole 27 formed therein, which are located radially (in the internal flow path 13a) Figure 1 The flow paths (up and down) are opposite to each other and extend from the inner flow path 13a to the outer side.
[0033] The first bearing hole 25 extends through the top flange 23. The first valve shaft 15a is inserted into the first bearing hole 25 with the first bushing 21a inserted on its outer side, and is supported by the first bearing hole 25 in a rotatable manner through the first bushing 21a. The upper end of the first valve shaft 15a inserted into the first bearing hole 25 protrudes from the top flange 23 and extends, so as to be able to connect with the drive unit provided on the top flange 23. The drive unit can be a lever-type drive unit, a gear-type drive unit, or an automatic drive unit. On the other hand, the lower ends of the first valve shaft 15a and the first bushing 21a inserted into the first bearing hole 25 protrude from the first bearing hole 25 toward the internal flow path 13a. Similarly, the second valve shaft 15b is inserted into the second bearing hole 27 with the second bushing 21b inserted on its outer side, and is supported by the second bearing hole 27 in a rotatable manner through the second bushing 21b. The lower end of the second bearing hole 27 is closed by the valve shaft support 29, and the lower ends of the second valve shaft 15b and the second bushing 21b inserted into the second bearing hole 27 abut against the valve shaft support 29. On the other hand, the upper ends of the second valve shaft 15b and the second bushing 21b inserted into the second bearing hole 27 protrude from the second bearing hole 27 toward the internal flow path 13a.
[0034] The valve body 13 contains a reinforced metal insert 31 that surrounds the first bearing bore 25 and the second bearing bore 27. While stainless steel for casting can be used as the metal material for the insert 31, it is not limited to this. Alternatively, the insert 31 can be made of other metal materials similar to the valve shaft 15, or it can be made of a non-metallic material, if it possesses higher mechanical strength than the valve body 13.
[0035] Figure 1In the illustrated embodiment, the insert 31 is generally cylindrical. Specifically, the insert 31 includes a generally cubic central portion, a cylindrical portion located further from the internal flow path 13a than the central portion, and a base portion located closer to the internal flow path 13a than the central portion, which is larger than the cylindrical portion and smaller than the central portion. It also has a through hole with a diameter larger than the first bearing hole 25 and the second bearing hole 27 formed at the center of the cylindrical portion, the central portion, and the base portion. A threaded hole is formed in the central portion for screwing in a screw when connecting the valve body 13 to a pipeline. The insert 31, with this shape, is positioned radially away from the first bearing hole 25 and the second bearing hole 27. Being embedded within the valve body 13 and not exposed within the first bearing hole 25 and the second bearing hole 27 prevents the metal insert 31 from contacting the liquid even if corrosive fluid enters the first bearing hole 25 and the second bearing hole 27.
[0036] The seat ring 17 may be formed of elastic materials such as ethylene propylene rubber (EPDM), chloroprene rubber (CR), isoprene rubber (IR), chlorosulfonated rubber (CSM), nitrile rubber (NBR), styrene-butadiene rubber (SBR), chlorinated polyethylene (CM), fluororubber (FKM), hydrogenated nitrile rubber (HNBR), polyurethane rubber (U), silicone rubber (VMQ, FVMQ), ethylene propylene rubber (EPM), acrylic rubber (ACM), and butyl rubber (IIR), or materials coated with fluorinated resins. However, these materials are only illustrative, and the materials are not particularly limited as long as there are no issues with strength or corrosion resistance for the intended use. The seat ring 17 includes a generally cylindrical ring body 17a extending along a central axis and flange portions 17b extending outward from two opposite ends of the ring body 17a along the central axis (see reference). Figure 3 A pair of through holes 17c, 17c are formed at opposite positions along the diameter direction of the ring body 17a, allowing the first valve shaft 15a and the second valve shaft 15b to pass through respectively. A ring-shaped valve seat portion 17d is formed on the inner circumferential surface of the ring body 17a. The outer circumferential edge of the valve body 19 abuts against the valve seat portion 17d, sealing the inner circumferential surface of the seat ring 17 with the outer circumferential edge of the valve body 19, thus enabling the valve body 19 to block the internal flow path 13a.
[0037] The valve body 19 is disposed inside the seat ring 17 mounted on the inner peripheral surface of the internal flow path 13a of the valve body 13. The valve body 19 is integrally formed by a contour forming member 33 made of synthetic resin material and generally in the shape of a disc, and a core material 35 made of metal material and surrounded by the contour forming member 33. In this embodiment, the valve body 19 is formed by injecting the synthetic resin material forming the contour forming member 33 into an injection molding mold in which the core material 35 is pre-provided. In this embodiment, although PVDF with high chemical resistance is used as the synthetic resin material forming the contour forming member 33, it is not limited to this and other synthetic resin materials such as PP, PVC, PE, PFA, or PVCPD can also be used. In this embodiment, although aluminum alloy for casting is used as the metal material forming the core material 35, it is not limited to this. As long as it has higher mechanical strength than the contour forming member 33, the core material 35 can also be formed from other metal materials like the valve shaft, or it can be formed from non-metallic materials.
[0038] On the outer periphery of the valve body 19, at opposite positions along the rotation axis R, a first valve shaft hole 37 and a second valve shaft hole 39 are provided, which are coaxial with the rotation axis R. Furthermore, when the first valve shaft 15a and the second valve shaft 15b are integrally formed and the valve shaft 15 is formed from a single valve shaft 15, the first valve shaft hole 37 and the second valve shaft hole 39 are also formed as a single through hole.
[0039] The first valve shaft hole 37 includes a first large-diameter hole portion 37a and a first small-diameter hole portion 37b. The first large-diameter hole portion 37a includes an open end (an opening facing the internal flow path 13a) and has a relatively large diameter. The first small-diameter hole portion 37b extends further from the first large-diameter hole portion 37a toward the inner side in the direction of the rotation axis R and has a relatively small diameter. The inner circumferential surface of the first large-diameter hole portion 37a is formed by a contour forming member 33, and the inner circumferential surface of the first small-diameter hole portion 37b is formed by a core material 35. The first valve shaft hole 37 has a first valve shaft 15a and a first bushing 21a inserted into it, which protrude from the first bearing hole 25 of the valve body 13 through the through hole 17c of the seat ring 17. The first large-diameter hole portion 37a of the first valve shaft hole 37 supports the first valve shaft 15a through the first bushing 21a. The first bushing 21a is not inserted into the first small-diameter bore 37b, but is directly inserted into the front end portion (hereinafter referred to as the front end portion) of the first valve shaft 15a. The front end portion of the first valve shaft 15a is fitted into the first small-diameter bore 37b in a manner that prevents it from rotating about the axis of rotation R. For example, by forming the front end portion of the first valve shaft 15a and the first small-diameter bore 37b into complementary polygonal or circular shapes with two chamfers, the front end portion of the first valve shaft 15a can be fitted into the first small-diameter bore 37b in a manner that prevents it from rotating. However, as long as the front end portion of the first valve shaft 15a can be fitted into the first small-diameter bore 37b in a manner that prevents it from rotating, the method of fitting the first valve shaft 15a and the first small-diameter bore 37b is not limited. In addition, since the first bushing 21a is not inserted into the first small-diameter bore 37b, only the inner circumferential surface of the first large-diameter bore 37a becomes the area that contacts the outer circumferential surface of the first bushing 21a.
[0040] Similar to the first valve shaft hole 37, the second valve shaft hole 39 includes a second large-diameter hole portion 39a and a second small-diameter hole portion 39b. The second large-diameter hole portion 39a has an open end (an opening facing the internal flow path 13a) and a relatively large diameter. The second small-diameter hole portion 39b extends further from the second large-diameter hole portion 39a toward the inner side in the direction of the rotation axis R and has a relatively small diameter. The inner circumferential surface of the second large-diameter hole portion 39a is formed by a contour forming member 33, while the inner circumferential surface of the second small-diameter hole portion 39b is formed by a core material 35. The second valve shaft hole 39 inserts a second valve shaft 15b and a second bushing 21b that protrude from the second bearing hole 27 of the valve body 13 through the through hole 17c of the seat ring 17. The second large-diameter hole portion 39a of the second valve shaft hole 39 supports the second valve shaft 15b through the second bushing 21b. The second bushing 21b is not inserted into the second small-diameter bore 39b, but is directly inserted into the front end portion (hereinafter referred to as the front end portion) of the second valve shaft 15b. Since the second bushing 21b is not inserted into the second small-diameter bore 39b, only the inner circumferential surface of the second large-diameter bore 39a becomes the area in contact with the outer circumferential surface of the second bushing 21b. Furthermore, since the second small-diameter bore 39b does not need to transmit rotational torque between itself and the second valve shaft 15b, it has a circular cross-sectional shape, which differs from the first small-diameter bore 37b of the first valve shaft bore 37. However, the second small-diameter bore 39b can also have the same structure as the first small-diameter bore 37b.
[0041] In the following description, the contour forming members 33 around the inner peripheral surfaces of the first large-diameter hole portion 37a and the second large-diameter hole portion 39a are specifically referred to as "shaft hole forming portion 41".
[0042] The first valve shaft bore 37 and the second valve shaft bore 39, except for the different cross-sectional shapes of their first small-diameter bore portion 37b and second small-diameter bore portion 39b, have the same structure as described above. Therefore, in the following description, the first valve shaft bore 37 will be used as the representative. The valve shaft will be described using the first valve shaft 15a as the representative, and the bushing will be described using the first bushing 21a as the representative. However, the description of the first valve shaft 15a, the first bushing 21a, and the first valve shaft bore 37 can be applied to replace these with the second valve shaft 15b, the second bushing 21b, and the second valve shaft bore 39. Furthermore, for the sake of brevity, the ordinal number "first" included in the names of the various components is omitted. However, this is not limited when it is necessary to distinguish between "first" and "second".
[0043] In this embodiment, the bushings 21 (first bushing 21a and second bushing 21b) are formed of PVDF, which has high resistance to corrosive fluids. The outer peripheral surface of the bushing 21a is provided with a plurality of sealing members 43, such as O-rings, to prevent fluid from entering the interior of the valve body 19 and from contacting the valve shaft 15. Figure 1In the embodiment shown, four sealing members 43 are arranged in the bushing 21a of the large-diameter bore 37a of the insertion valve shaft bore 37.
[0044] The core material 35 includes a central portion 35a and a generally lattice-shaped main reinforcing portion 35b arranged symmetrically around the central portion 35a. A generally cylindrical (preferably cylindrical) shaft hole reinforcing portion 35c is provided at the upper and lower ends of the central portion 35a, respectively. In the embodiment shown in the figure, the shaft hole reinforcing portions 35c have holes with diameters larger than the first valve shaft hole 37 and the second valve shaft hole 39 formed in the generally cubic portions at the upper and lower ends of the central portion 35a. It is preferable that the shaft hole reinforcing portion 35c has the same shape as the central portion 35a. Such a shaft hole reinforcing portion 35c extends into the shaft hole constituting portion 41 that forms the large-diameter hole portion 37a, and surrounds at least a portion of the radially outer side of the large-diameter hole portion 37a in the direction of its rotation axis, thereby reinforcing the shaft hole constituting portion 41 formed of synthetic resin material. When the large-diameter bore 37a supports the shear force and bending moment generated in the valve body due to the fluid pressure acting on the valve body 19, the force acting from the valve shaft 15 on the large-diameter bore 37a and the shaft bore component 41 is supported by the shaft bore reinforcement 35c, suppressing the deformation of the shaft bore component 41. As a result, the sealing member 43 between the inner circumferential surface of the large-diameter bore 37a and the outer circumferential surface of the bushing 21a can be reliably maintained. Figure 1 and Figure 2 As shown, it is preferable that the shaft hole reinforcement portion 35c is provided with a plurality of through holes 35d that penetrate its inner and outer peripheral surfaces. These through holes 35d serve as pathways for the synthetic resin material forming the shaft hole component portion 41 when the core material 35 is placed in the mold and the contour forming member 33 is injection molded, thereby suppressing injection molding defects.
[0045] Furthermore, the shaft hole reinforcement portion 35c surrounds the outer radial direction of the first valve shaft hole 37 and the second valve shaft hole 39, and is disposed separately from the inner circumferential surface of the first valve shaft hole 37 and the second valve shaft hole 39, so as to be embedded in the shaft hole constitutive portion 41 and not exposed in the first valve shaft hole 37 and the second valve shaft hole 39. This is to ensure that even if corrosive fluid enters the first large-diameter hole portion 37a of the first valve shaft hole 37 and the second large-diameter hole portion 39a of the second valve shaft hole 39, the metal shaft hole reinforcement portions 35c, 35c will not come into contact with the liquid.
[0046] Next, refer to Figures 3 to 8 The detailed description is based on the support structure of the valve shaft 15 of the valve body 13 and valve body 19.
[0047] First refer to Figure 3 and 4 Detailed explanation Figure 1The butterfly valve 11 shown is constructed according to the support portion of the valve shaft 15 of the valve body 13.
[0048] In the butterfly valve 11, the first bearing hole 25 and the first bushing 21a are configured to have a shape in which a gap (space) is formed between the inner peripheral surface of the first bearing hole 25 and the outer peripheral surface of the first bushing 21a in the region of the opening portion adjacent to the opening of the first bearing hole 25 supporting the first valve shaft 15a into the internal flow path 13a. Figure 3 and Figure 4 In one embodiment shown, in the region adjacent to the opening of the first bearing hole 25, a hollow is formed from the outer peripheral surface of the first bushing 21a. An annular recessed portion 45 extending in the circumferential direction is provided on the outer peripheral surface of the first bushing 21a, thus forming an annular gap (space) between the inner peripheral surface of the first bearing hole 25 and the outer peripheral surface of the first bushing 21a. However, in the region adjacent to the opening of the first bearing hole 25, by hollowing out the inner peripheral surface of the first bearing hole 25 and providing an annular recessed portion 45 extending in the circumferential direction on the inner peripheral surface of the first bearing hole 25, a gap can be formed between the inner peripheral surface of the first bearing hole 25 and the outer peripheral surface of the first bushing 21a. There are no particular limitations on the method of forming the gap between the inner peripheral surface of the first bearing hole 25 and the outer peripheral surface of the first bushing 21a. However, if the recessed portion 45 is provided on the inner peripheral surface of the first bearing hole 25, there is a risk that the wall thickness around the first bearing hole 25, which supports the bending moment, will become thinner, potentially reducing its strength. Therefore, it is preferable to provide the recessed portion 45 on the outer peripheral surface of the first bushing 21a, which is easier to machine than the first bearing hole 25 of the valve body 13.
[0049] When the butterfly valve 11 is closed, fluid pressure acts on the valve body 19, causing the valve body 19 to move towards the secondary side (downstream side), generating a bending moment on the first valve shaft 15a fixed to the valve body 19. The first bearing hole 25 supports the force generated by this bending moment through the first bushing 21a. At this time, if the inner circumferential surface of the first bearing hole 25 comes into contact with the outer circumferential surface of the first bushing 21a, stress concentration occurs near the opening of the first bearing hole 25. Furthermore, due to wear of the seat ring 17, fluid in the internal flow path 13a may break through the seal between the valve seat portion 17d around the through hole 17c of the seat ring 17 and the outer circumferential edge portion around the first valve shaft hole 37 of the valve body 19, as well as the seal between the inner circumferential surface of the through hole 17c of the seat ring 17 and the outer circumferential surface of the first bushing 21a, and intrude into the outer circumferential surface of the first bearing hole 25 or between the outer circumferential surface of the seat ring 17 and the inner circumferential surface of the internal flow path 13a. Even in this case, to prevent the fluid in the internal flow path 13a from contacting the insert 31 made of metal material, the insert 31 is covered by the synthetic resin material of the valve body 13 and configured to be separated from the inner circumferential surface of the first bearing hole 25 and the inner circumferential surface of the internal flow path 13a of the valve body 13 and not exposed to the outside. That is, there is no insert 31 near the opening of the first bearing hole 25, and the area near the opening of the first bearing hole 25 is formed only by synthetic resin material. As a result, the first bearing hole 25 cannot withstand the force generated by the bending moment transmitted from the first valve shaft 15a through the first bushing 21a and will be damaged.
[0050] However, in the butterfly valve 11, as described above, a gap (space) is formed between the inner circumferential surface of the first bearing hole 25 and the outer circumferential surface of the first bushing 21a in the region adjacent to the opening of the first bearing hole 25. Therefore, even when the valve is closed, the fluid pressure causes the first valve shaft 15a to exert a bending moment through the first bushing 21a on the first bearing hole 25. The gap between the inner circumferential surface of the first bearing hole 25 and the outer circumferential surface of the first bushing 21a in the region adjacent to the opening of the first bearing hole 25 acts as a buffer space, preventing the outer circumferential surface of the first bushing 21a from contacting the inner circumferential surface of the first bearing hole, and thus preventing the transmission of force caused by the bending moment from the outer circumferential surface of the first bushing 21a to the inner circumferential surface of the first bearing hole 25. As a result, the butterfly valve 11 can suppress damage to the resin material near the opening of the first bearing hole 25 of the valve body 13.
[0051] When the valve body 19 is subjected to fluid pressure, and the first bearing bore 25 supports the bending moment from the first valve shaft 15a, the fulcrum becomes the side opposite to the internal flow path 13a. The closer to the internal flow path 13a, the greater the displacement of the first valve shaft 15a from its rotation axis R. Therefore, the size of the gap (space) between the inner circumferential surface of the first bearing bore 25 and the outer circumferential surface of the first bushing 21a, i.e., the depth of the recess 45, is preferably formed into a cone shape with a larger opening towards the internal flow path 13a as it gets closer to the first bearing bore 25. In this way, the amount of hollowing out can be minimized.
[0052] Furthermore, if the size of the gap (space) between the inner circumferential surface of the first bearing hole 25 and the outer circumferential surface of the first bushing 21a, i.e., the depth of the recessed portion 45, is too large, it will allow deformation (i.e., bending) of the first valve shaft 15a, resulting in a larger displacement of the valve body 19 and a deterioration of the valve seat sealing performance. Therefore, it is preferable to adjust the amount of hollowing out in the gap, i.e., the recessed portion 45, so that even if the valve body 19 is displaced under pressure from the fluid, it will not transmit the force caused by the bending moment.
[0053] In butterfly valve 11, such as Figure 4 As detailed, the insert 31 extends at least radially outward from a portion of the recessed portion 45 along the direction of the rotation axis R. By configuring the insert 31 to extend near the opening of the first bearing bore 25 along the direction of the rotation axis R, the strength around the opening of the first bearing bore 25 is improved, enabling the first bearing bore 25 to withstand the force generated by the bending moment acting by the first valve shaft 15a through the first bushing 21a, even when a greater fluid pressure is applied to the valve body 19. To further enhance the strength of the first bearing bore 25, it is preferable to increase the thickness of the insert 31 as much as possible.
[0054] Similarly, in the butterfly valve 11, the second bearing hole 27 and the second bushing 21b are configured such that the region adjacent to the opening of the second bearing hole 27, which supports the second valve shaft 15b, facing the internal flow path 13a, has a shape that forms an annular gap (space) between the inner circumferential surface of the second bearing hole 27 and the outer circumferential surface of the second bushing 21b. The structure and function of the second bearing hole 27, the second bushing 21b, and their surrounding area are the same as those of the first bearing hole 25, the first bushing 21a, and their surrounding area described above, and therefore, the description is omitted here.
[0055] Figure 5 and Figure 6 show Figure 1This is a modified example of the structure of the support portion of the valve shaft 15 of the valve body 13 in the butterfly valve 11 shown. In this modified example, the support portion of the valve shaft 15 of the valve body 13 is characterized by having multiple through holes 31'a extending from the inner circumferential surface to the outer circumferential surface in the cylindrical insert 31'. Furthermore, although the insert 31' extends to the radially outer side of the portion (recessed portion 45) forming an annular gap (space) between the inner circumferential surface of the first bearing hole 25 and the outer circumferential surface of the first bushing 21a, it is relatively... Figure 3 and Figure 4 At the point where the implementation shown is shorter and thinner, and... Figure 3 and Figure 4 The embodiment shown differs from the structure of the support portion of the valve shaft 15 in the valve body 13, but other aspects are the same. Figure 3 and Figure 4 The embodiment shown has the same structure as the support portion of the valve shaft 15 of the valve body 13. If the strength of the first bearing hole 25 is reinforced, the recessed portion 45 can be provided on the inner circumferential surface of the first bearing hole 25.
[0056] The through hole 31'a of the insert 31' serves as a channel for the synthetic resin material when the insert 31' is placed in the mold and the synthetic resin material forming the valve body 13 is injection molded, thereby suppressing the occurrence of injection molding defects. Furthermore, the insert 31' only needs to extend in the direction of the rotation axis R to at least a portion of the portion (recessed portion 45) forming the gap space between the inner circumferential surface of the first bearing hole 25 and the outer circumferential surface of the first bushing 21a, extending radially outward; its length and thickness can be appropriately designed.
[0057] Furthermore, although the above description pertains to the first bearing hole 25, the first bushing 21a and its surrounding portion, the second bearing hole 27, the second bushing 21b and its surrounding portion also have the same construction.
[0058] Next, refer to Figure 7 and Figure 8 Detailed explanation Figure 1 The butterfly valve 11 shown is constructed according to the support portion of the valve shaft 15 of the valve body 19.
[0059] In the butterfly valve 11, the first bushing 21a and the first valve shaft 15a are configured such that a gap (space) is formed between the inner peripheral surface of a portion of the first bushing 21a located inside the radial direction of the shaft hole constituting portion 41 of the contour forming member 33 and the outer peripheral surface of a portion of the first valve shaft 15a located inside the radial direction of the shaft hole constituting portion 41 of the contour forming member 33. Figure 7 In the embodiment shown, the outer peripheral surface of the portion of the first valve shaft 15a located within the shaft hole constituting part 41 of the contour forming member 33 is hollowed out, by means of... Figure 8As shown, an annular recessed portion 47 extending in the circumferential direction is provided on the outer peripheral surface of the first valve shaft 15a, and a gap is formed between the inner peripheral surface of the first bushing 21a and the outer peripheral surface of the first valve shaft 15a. However, it is also possible to hollow out the inner peripheral surface of the portion of the first bushing 21a located radially inside the shaft hole constituting portion 41 of the contour forming member 33, and provide an annular recessed portion 47 extending in the circumferential direction on the inner peripheral surface of the first bushing 21a, thus forming a gap between the inner peripheral surface of the first bushing 21a and the outer peripheral surface of the first valve shaft 15a. There is no particular limitation on the method of forming a gap between the inner peripheral surface of the first bushing 21a and the outer peripheral surface of the first valve shaft 15a. However, when the first bushing 21a is made of resin material and the first valve shaft 15a is made of metal material, since the latter has high strength, it is preferable that the recessed portion 47 is provided on the outer peripheral surface of the first valve shaft 15a.
[0060] When the butterfly valve 11 closes, fluid pressure acts on the valve body 19, causing the valve body 19 to move towards the secondary side (downstream side). The first valve shaft hole 37 supports the shear force and bending moment occurring in the valve body 19 through the first bushing 21a. At this time, the reaction force from the first valve shaft 15a supported by the first valve shaft hole 37 is transmitted to the inner circumferential surface of the first valve shaft hole 37 of the valve body 19. When the inner circumferential surface of the first bushing 21a and the outer circumferential surface of the first valve shaft 15a come into contact with each other in the first large-diameter hole portion 37a of the first valve shaft hole 37, the reaction force from the first valve shaft 15a is transmitted through the first bushing 21a to the inner circumferential surface of the first large-diameter hole portion 37a of the first valve shaft hole 37. The inner circumferential surface of the first large-diameter bore portion 37a is formed by the shaft hole constituting portion 41 and covered by a contour forming member 33 made of synthetic resin material so that the shaft hole reinforcement portion 35c of the core material 35 does not come into contact with the liquid (that is, the shaft hole reinforcement portion 35c is configured to be separate from the inner circumferential surface of the first large-diameter bore portion 37a and the outer circumferential surface of the valve body 19). In particular, the portion around the opening of the shaft hole constituting portion 41 facing outward is made only of synthetic resin material. Therefore, the first large-diameter bore portion 37a of the first valve shaft hole 37 may not be able to withstand the reaction force (shear force and bending moment) transmitted from the first valve shaft 15a through the first bushing 21a and may be damaged. However, in the butterfly valve 11, as described above, a gap (space) is formed between the inner circumferential surface of a portion located in the radial direction inside the shaft hole constituting portion 41 that forms the first large-diameter bore portion 37a and the outer circumferential surface of the first valve shaft 15a located in the radial direction inside the shaft hole constituting portion 41. Therefore, even when the valve is closed, fluid pressure acts on the valve body 19 and generates a bending moment in the valve body 19, the gap between the outer peripheral surface of the first valve shaft 15a and the inner peripheral surface of the first bushing 21a within the first large-diameter bore portion 37a formed by the shaft bore portion 41 acts as a buffer space, preventing contact between the outer peripheral surface of the first valve shaft 15a and the inner peripheral surface of the first bushing 21a, thus preventing force transmission from the outer peripheral surface of the first valve shaft 15a to the first bushing 21a, and preventing force transmission from the first bushing 21a to the shaft bore portion 41. As a result, the butterfly valve 11 can suppress damage to the resin material portion (shaft bore portion 41) near the opening of the first valve shaft bore 37 of the valve body 19.
[0061] The inward portion 47 is preferably formed to extend along the entire area of the rotation axis R, spanning the portion located within the first large-diameter hole portion 37a formed by the shaft hole constituting portion 41 on the outer peripheral surface of the first valve shaft 15a (i.e., the outer peripheral portion of the first valve shaft 15a in the opposite direction, where the inner peripheral surface of the first valve shaft hole 37 in the shaft hole constituting portion 41 contacts the outer peripheral surface of the first bushing 21a). Furthermore, to improve the strength of the shaft hole constituting portion 41, the thickness of the shaft hole reinforcing portion 35c of the core material 35 is preferably increased as much as possible.
[0062] Furthermore, if the size of the gap (space) between the outer peripheral surface of the first valve shaft 15a and the inner peripheral surface of the first bushing 21a, i.e., the depth of the recessed portion 47, is too large, the displacement of the valve body 19 relative to the first valve shaft 15a will increase, and the valve seat sealing performance will deteriorate. Therefore, it is preferable to adjust the amount of hollowing out in the gap, i.e., the recessed portion 47, so that even if the valve body 19 is displaced under pressure from the fluid, it will not transmit the force caused by the bending moment.
[0063] Similarly, in the butterfly valve 11, both the second valve shaft 15b and the second bushing 21b are configured such that a gap (space) is formed between the inner peripheral surface of a portion of the second bushing 21b located radially inside the shaft hole constituting portion 41 of the contour forming member 33 and the outer peripheral surface of a portion of the second valve shaft 15b located radially inside the shaft hole constituting portion 41 of the contour forming member 33. The structure and function of the second valve shaft 15b, the second bushing 21b, the second valve shaft hole 39 and its surrounding area are the same as those of the first valve shaft 15a, the first bushing 21a, the first valve shaft hole 37 and its surrounding area described above. Further explanation is omitted here.
[0064] Although the butterfly valve 11 according to the present invention has been described above with reference to the illustrated embodiments, the present invention is not limited to the illustrated embodiments. For example, in the illustrated embodiments, inserts 31, 31 are provided around the first bearing hole 25 and the second bearing hole 27, and shaft hole reinforcing portions 35c, 35c are provided around the first valve shaft hole 37 and the second valve shaft hole 39, but these are not necessary structures and may be omitted.
[0065] [Symbol Explanation]
[0066] 11 Butterfly Valve
[0067] 13 Valve Body
[0068] 13a internal flow path
[0069] 15 valve shaft
[0070] 15a First valve shaft
[0071] 15b Second valve shaft
[0072] 19 Valve Body
[0073] 21 bushing
[0074] 21a First bushing
[0075] 21b Second bushing
[0076] 25 First bearing hole
[0077] 27 Second bearing hole
[0078] 31 inserts
[0079] 31' insert
[0080] 33 Profile forming components
[0081] 35 core material
[0082] 37 First valve shaft hole
[0083] 39 Second valve shaft hole
[0084] 41 Shaft Hole Components
[0085] 45 Inward Reduction Section
[0086] 47 Inner Section
Claims
1. A butterfly valve, comprising: The valve body, at least its surface, is made of resin material and has internal flow channels formed therein; The valve shaft is supported on the valve body in a rotatable manner; The valve body is connected to the valve shaft and supported on the valve body in a rotatable manner, and is disposed within the internal flow path; as well as The bushing is inserted on the outside of the valve shaft. The valve body has a bearing bore with an opening facing the internal flow path opening. The valve body also has a valve shaft bore, which is supported by the bearing bore and the bushing through which the valve shaft bore allows it to rotate. The bearing bore and the bushing have an annular gap between the inner circumferential surface of the bearing bore and the outer circumferential surface of the bushing in the region adjacent to the opening. The bushing has an annular recessed portion on the outer circumferential portion adjacent to the opening. The gap between the inner circumferential surface of the bearing bore and the outer circumferential surface of the bushing is formed by the recessed portion.
2. The butterfly valve of claim 1, wherein the valve shaft extends along the rotation axis of the valve body, and the valve body further includes a cylindrical insert for reinforcing the valve body, the insert being configured to be separate from and surround the bearing bore, and extending in the direction of the rotation axis to at least surround a portion of the outer side of the recess.
3. The butterfly valve of claim 2, wherein the gap includes a conical portion adjacent to the opening, the conical portion being formed such that the gap between the inner circumferential surface of the bearing bore and the outer circumferential surface of the bushing is larger the closer it is to the opening.