Butterfly valve

Abstract

To provide a butterfly valve with which exhaust gas hardly leaks out of an exhaust pipe even under high back pressure.SOLUTION: A butterfly valve comprises: a valve plate 110 provided inside an exhaust pipe EP; a valve shaft 120 which crosses the exhaust pipe EP and holds the valve plate 110; a bearing unit 140 that has a sealing bush 141 and a support bush 142 which are distinct and annular and into which the valve shaft 120 is inserted, and that axially supports the valve shaft 120 in a slidable manner; and a housing 150 which is attached to the exhaust pipe EP and accommodates the bearing unit 140 disposed outside the exhaust pipe EP. The support bush 142 is disposed between the housing 150 and the sealing bush 141 and is in contact with the housing 150 at an outer peripheral surface 142A of the support bush 142. The sealing bush 141 is in contact with the housing 150 at an outer peripheral surface 141A of the sealing bush 141 and is in contact with a flange 121 of the valve shaft 120 at a valve shaft-facing surface 141B of the sealing bush 141.SELECTED DRAWING: Figure 2

Description

Technical Field

[0005]

[0001] The present invention relates to a butterfly valve, and more particularly to a butterfly valve that opens and closes an exhaust pipe communicating with an exhaust port of an engine.

Background Art

[0002] Conventionally, as an exhaust device (butterfly valve) for controlling the exhaust gas flow in an exhaust pipe communicating with an exhaust port of a motorcycle engine, there is known an exhaust device including a valve body (valve plate) disposed in the exhaust pipe, a valve shaft fixed or integrally formed with the valve body and disposed so as to cross the exhaust pipe, and a pair of bearing members rotatably supporting both end portions in the axial length direction of the valve shaft, and rotating the valve body around the valve shaft axis (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the above-described butterfly valve is installed in an exhaust pipe communicating with an exhaust port of an automobile engine, the back pressure becomes higher than that in a motorcycle, so there is a risk that the bearing member cannot withstand the radial load due to the back pressure when the valve body closes the exhaust pipe. Therefore, in order to withstand the back pressure caused by an automobile engine, if the bearing member is changed to a hard material, the sealing performance of the bearing member may deteriorate, and exhaust gas may leak to the outside through a gap between the bearing member and the valve shaft, or exhaust soot may accumulate between the bearing member and the valve shaft. This problem of exhaust soot accumulation becomes more serious when the engine fuel becomes biodiesel fuel, because exhaust soot is more likely to occur compared to conventional petroleum fuel.

[0005] Therefore, the present invention solves the problems of the prior art described above, that is, the object of the present invention is to make it difficult for exhaust gas to leak out of the exhaust pipe even under high back pressure. Furthermore, it will continue to function even if the sealing bush and the valve stem flange become stuck together. The objective is to provide a butterfly valve. [Means for solving the problem]

[0006] The invention according to claim 1 is a butterfly valve for opening and closing an exhaust pipe communicating with the exhaust port of an engine, comprising: a valve plate provided in the exhaust pipe; a valve stem that traverses the exhaust pipe and holds the valve plate; a bearing unit that slidably supports the valve stem by having an annular sealing bush and a support bush separately inserted into the valve stem; and a housing attached to the exhaust pipe and housing the bearing unit which is located outside the exhaust pipe, wherein the support bush of the bearing unit is positioned between the housing and the sealing bush of the bearing unit and the outer circumferential surface of the support bush abuts against the housing; and the outer circumferential surface of the sealing bush abuts against the housing and the valve stem-facing surface of the sealing bush abuts against the flange of the valve stem. Furthermore, when the sealing bush of the bearing unit and the flange of the valve shaft become fixed together, the outer circumferential surface of the sealing bush slides against the housing. This will solve the aforementioned problems.

[0007] The invention according to claim 2 further solves the aforementioned problems by, in addition to the configuration of the butterfly valve described in claim 1, the sealing bush of the bearing unit being softer than the support bush of the bearing unit, and the inner diameter of the sealing bush being greater than or equal to the inner diameter of the support bush.

[0008] The invention according to claim 3 further solves the aforementioned problems by, in addition to the configuration of the butterfly valve described in claim 1, forming a gap between the support bush and the valve stem, and having an inner diameter larger than the inner diameter of the support bush.

[0009] The invention according to claim 4 further solves the aforementioned problems by having, in addition to the configuration of the butterfly valve described in any one of claims 1 to 3, the coefficient of thermal expansion of the support bush and the coefficient of thermal expansion of the housing being substantially the same. [Effects of the Invention]

[0010] According to the butterfly valve of the invention of claim 1, the sealing bush of the bearing unit has a housing on its outer circumferential surface. Freely slidingBy making contact with the valve shaft flange on the valve shaft-facing surface of the sealing bush, the space between the housing and the bearing unit is sealed, and the space between the valve shaft and the bearing unit is also sealed, thereby preventing exhaust gas flowing inside the exhaust pipe from leaking out of the exhaust pipe through the housing. Furthermore, the support bush of the bearing unit is positioned between the housing and the sealing bush of the bearing unit, and the outer surface of the support bush abuts against the housing. This allows the support bush to support the radial load on the valve plate caused by the exhaust gas flowing through the exhaust pipe. Therefore, even if a high load is applied to the valve plate when it blocks the exhaust pipe, deformation or abnormal friction of the sealing bush can be prevented. Furthermore, even if the sealing bush of the bearing unit becomes stuck to the flange of the valve stem due to rust or other reasons, the sealing bush and the support bush continue to slide against each other, while the outer surface of the sealing bush slides against the housing, allowing the butterfly valve to continue functioning. Therefore, even under high back pressure, it prevents exhaust gas from leaking out of the exhaust pipe. Even if the sealing bush and the valve stem flange become stuck together, the butterfly valve will continue to function. It is possible.

[0011] According to the butterfly valve of the invention of claim 2, in addition to the effects of the butterfly valve of the invention of claim 1, the sealing bush of the bearing unit is softer than the support bush of the bearing unit. Therefore, compared to the case where the sealing bush is harder than the support bush, the sealing bush is more easily deformed to conform to the shape of the housing or the flange of the valve stem, thus ensuring reliable sealing not only between the housing and the bearing unit but also between the valve stem and the bearing unit. Furthermore, because the inner diameter of the sealing bush is greater than or equal to the inner diameter of the support bush, the valve stem contacts the inner surface of the support bush, which is harder than the sealing bush, before it contacts the inner surface of the sealing bush. Therefore, even if a high load is applied to the valve plate when the valve plate blocks the exhaust pipe, the valve stem can be reliably supported by the support bush. Therefore, even under high back pressure, it is possible to reliably prevent exhaust gases from leaking outside the exhaust pipe.

[0012] According to the butterfly valve of the invention of claim 3, in addition to the effects of the butterfly valve of the invention of claim 1, a gap is formed between the support bush and the valve stem, and the inner diameter of the sealing bush is larger than the inner diameter of the support bush. As a result, the valve stem contacts the inner surface of the support bush before it contacts the inner surface of the sealing bush. Therefore, even if a high load is applied to the valve plate when the valve plate blocks the exhaust pipe, the valve stem can be reliably supported by the support bush.

[0013] According to the butterfly valve of the invention of claim 4, in addition to the effects of the butterfly valve of the invention of any one of claims 1 to 3, when the butterfly valve becomes hot due to exhaust gas or the like, the support bush also expands in accordance with the housing, so that the space between the support bush and the housing can be kept sealed. [Brief explanation of the drawing]

[0014] [Figure 1] Perspective view of an exhaust pipe incorporating a butterfly valve according to a first embodiment of the present invention. [Figure 2] Vertical sectional view of FIG. 1. [Figure 3] Enlarged view III of FIG. 2. [Figure 4] Enlarged view IV of FIG. 3. [Figure 5] Enlarged cross-sectional view of a main part of a butterfly valve according to a second embodiment of the present invention. [Figure 6] Enlarged cross-sectional view of a main part of a butterfly valve according to a third embodiment of the present invention. [Figure 7] Enlarged cross-sectional view of a main part of a butterfly valve according to a fourth embodiment of the present invention. [Figure 8A] Enlarged cross-sectional view of a main part of a butterfly valve according to a fifth embodiment of the present invention. [Figure 8B] Enlarged view IIIVB of FIG. 8A. [Figure 9A] Exploded perspective view of a bearing unit in a butterfly valve according to a sixth embodiment of the present invention [Figure 9B] Enlarged cross-sectional view of a main part of a butterfly valve in the IXB-IXB cross-section of FIG. 9A.

Mode for Carrying Out the Invention

[0015] The present invention is a butterfly valve that opens and closes an exhaust pipe communicating with an exhaust port of an engine, and includes a valve plate provided in the exhaust pipe, a valve shaft that holds the valve plate across the exhaust pipe, an annular sealing bush and a support bush that are each separate and slidably support the valve shaft, and a housing that is attached to the exhaust pipe and houses the bearing unit disposed outside the exhaust pipe. The support bush of the bearing unit is disposed between the housing and the sealing bush of the bearing unit and abuts against the housing on the outer peripheral surface of the support bush, and the sealing bush of the bearing unit abuts against the housing on the outer peripheral surface of this sealing bush and Freely sliding abuts against the flange of the valve shaft on the valve shaft facing surface of the sealing bush Furthermore, when the sealing bush of the bearing unit becomes fixed to the flange of the valve stem, the outer surface of the sealing bush slides against the housing. , and it is difficult for exhaust gas to leak outside the exhaust pipe even under high back pressureFurthermore, it will continue to function even if the sealing bush and the valve stem flange become stuck together. As long as it is a [specific concept], its concrete embodiment may be anything.

[0016] For example, the butterfly valve in the present invention is installed in an exhaust pipe that communicates with the exhaust port of an engine of a four-wheeled vehicle. However, the butterfly valve of the present invention is not limited to four-wheeled vehicles; it may also be installed in a motorcycle, and the four-wheeled vehicle may be a gasoline vehicle or a diesel vehicle. In other words, the engine with the connected exhaust pipes can be either a gasoline engine or a diesel engine. Furthermore, while diesel engines used in trucks generally have higher back pressure than gasoline engines used in passenger cars, the butterfly valve according to the present invention can sufficiently suppress the leakage of exhaust gas outside the exhaust pipe. [Examples]

[0017] A butterfly valve 100, which is a first embodiment of the present invention, will be described below with reference to Figures 1 to 4.

[0018] <1. Installation environment for butterfly valves> First, the environment in which the butterfly valve 100 is installed will be described based on Figure 1, a perspective view of an exhaust pipe incorporating a butterfly valve, which is a first embodiment of the present invention.

[0019] The butterfly valve 100 in this embodiment opens and closes an exhaust pipe EP that communicates with the exhaust port (not shown) of a diesel engine of a four-wheeled vehicle, and is positioned in the middle of the cylindrical exhaust pipe EP, as shown in Figure 1.

[0020] <2. Structure of a butterfly valve> Next, the structure of the butterfly valve 100 will be described based on Figures 1 to 4. Figure 2 is a longitudinal section of Figure 1, Figure 3 is an enlarged view of III in Figure 2, and Figure 4 is an enlarged view of IV in Figure 3.

[0021] <2.1. Main components of a butterfly valve> As shown in Figures 1 and 2, the butterfly valve 100 comprises a disc-shaped valve plate 110 provided inside the exhaust pipe EP, a valve stem 120 that crosses the exhaust pipe EP and holds the valve plate 110, a connecting bolt 130 that connects the valve plate 110 and the valve stem 120, a bearing unit 140 that slidably supports the valve stem 120, and a housing 150 that is attached to the exhaust pipe EP and houses the bearing unit 140 which is located outside the exhaust pipe EP.

[0022] <2.1.1. Valve Plate> As shown in Figure 2, the valve plate 110 is located upstream of the valve stem 120. As a result, even if the back pressure of the exhaust gas EG is applied to the valve plate 110, the valve plate 110 is pressed against the valve stem 120, making it difficult for the valve plate 110 to detach from the valve stem 120.

[0023] <2.1.2. Valve stem> As shown in Figure 2, flanges 121 that protrude radially are formed on both ends of the valve stem 120. As shown in Figure 3, the diameter φF of this flange 121 is smaller than the diameter φP of the shaft insertion hole EP1 formed in the exhaust pipe EP. Furthermore, the diameter of the valve stem 120 outside the flange 121 remains constant all the way to the end, as shown in Figure 3. Furthermore, a male thread is formed on one end of the valve stem 120 (the upper end in Figure 2).

[0024] <2.1.3. Bearing Unit> As shown in Figure 2, the bearing unit 140 consists of an annular sealing bush 141 and a support bush 142 that insert the valve stem 120.

[0025] As shown in Figures 2 and 3, the sealing bush 141 is a separate component from the support bush 142 and is softer than the support bush 142 (for example, its Young's modulus is 0.15 to 0.5 GPa or higher, its Poisson's ratio is about 0.2 to 0.3, and its compressive strength is 46 MPa or less). The sealing bush 141 is pressed against the housing 150 on its outer circumferential surface 141A and abuts against the flange 121 of the valve stem 120 on its valve stem opposing surface 141B. Therefore, the space between the sealing bush 141 and the housing 150 is sealed, and the space between the sealing bush 141 and the flange 121 of the valve stem 120 is also sealed. Furthermore, the inner diameter φs of the sealing bush 141 is slightly larger than the inner diameter φb of the support bush 142. The inner diameter φs of the sealing bush 141 may be equal to the inner diameter φb of the support bush 142.

[0026] As shown in Figure 4, the sealing bush 141 is formed from a mesh-like metal aggregate 141a woven from metal wire (stainless steel wire in this embodiment) and graphite 141b filled in this metal aggregate 141a. The metal aggregate 141a is formed by repeatedly bending it in the axial direction of the sealing bush 141 (i.e., in the direction in which the valve stem 120 extends; vertical direction in Figure 4). Therefore, the metal aggregate 141a is prone to axial expansion. The graphite 141b is expanded graphite, designed to easily penetrate the gaps in the metal aggregate 141a.

[0027] In this embodiment, the support bush 142 is made of the same stainless steel as the housing 150 and has a coefficient of thermal expansion that is almost the same as that of the housing 150. As a result, when the butterfly valve 100 becomes hot due to exhaust gas or the like, the support bush 142 also expands in accordance with the housing 150, thus maintaining a continuous seal between the support bush 142 and the housing 150.

[0028] As shown in Figures 2 and 3, the support bush 142 is positioned between the housing 150 and the sealing bush 141, and is in pressure contact with the housing 150 at its outer peripheral surface 142A. Furthermore, the axial length Lb of the support bush 142 is longer than the axial length Ls of the sealing bush 141.

[0029] <2.1.4. Housing> The housing 150 is a component that covers the shaft insertion hole EP1 of the exhaust pipe EP, and as shown in Figure 2, it consists of a flanged, bottomed cylindrical fixed-side housing 151 that is attached to the lower side of the exhaust pipe EP, and a flanged, bottomed cylindrical detachable-side housing 152 that is attached to the upper side of the exhaust pipe EP.

[0030] The fixed housing 151 is integrated with the exhaust pipe EP by welding or other means to prevent exhaust gas EG from leaking from between it and the exhaust pipe EP.

[0031] The detachable housing 152 is in contact with the exhaust pipe EP, and as shown in Figure 3, a through hole 152a for inserting the valve stem 120 is formed on its bottom surface. As shown in Figure 3, the diameter φh of this through hole 152a is slightly larger than the diameter φd of the valve stem 120.

[0032] Furthermore, the inner diameter of the housing 150 (i.e., the inner diameter of the fixed-side housing 151 and the inner diameter of the detachable-side housing 152) φi is slightly larger than the diameter φF of the flange 121 of the valve stem 120, and smaller than the diameter φP of the shaft insertion hole EP1 of the exhaust pipe EP, as shown in Figure 3.

[0033] <2.2. Other components of the butterfly valve> Furthermore, the butterfly valve 100 includes a coil-shaped compression spring 160 that presses the detachable housing 152 against the exhaust pipe EP, and a valve shaft rotation mechanism 170 that rotates the valve shaft 120.

[0034] <2.2.1. Compression Spring> As shown in Figure 2, the compression spring 160 is a torsion coil spring, positioned between the detachable housing 152 and the valve stem rotation mechanism 170, and biases the detachable housing 152 toward the exhaust pipe EP. This compression spring 160 ensures that the detachable housing 152 makes contact with the exhaust pipe EP in a way that prevents exhaust gas EG from leaking out.

[0035] <2.2.2. Valve shaft rotation mechanism> As shown in Figure 1, the valve stem rotation mechanism 170 includes an annular rotating plate 171 that contacts the other end of the compression spring 160, a fixing nut 172 that fixes the rotating plate 171 to the valve stem 120, a stopper 173 that rises from the exhaust pipe EP and prevents the rotating plate 171 from rotating, and a valve stem drive actuator (not shown) that rotates the valve stem 120.

[0036] Furthermore, when the valve plate 110 is blocking the exhaust pipe EP as shown in Figure 1, the compression spring 160 is twisted by the valve shaft drive actuator. In other words, when the compression spring 160 is not twisted, that is, when the valve shaft drive actuator is not operating, the valve plate 110 does not block the exhaust pipe EP, and the exhaust gas EG is able to flow freely through the exhaust pipe EP.

[0037] The rotating plate 171 rotates integrally with the valve shaft 120 and, as shown in Figure 1, has a spring retaining portion 171a that extends down from the rotating plate 171 and contacts the tip of one end of the compression spring 160, and two arm portions 171b that contact the stopper 173.

[0038] The spring retaining portion 171a is L-shaped and is in contact with the tip portion of one end of the compression spring 160 on two sides.

[0039] The arm portion 171b is formed from a horizontal portion that extends horizontally and a hanging portion that rises from the tip of the horizontal portion and comes into contact with the stopper 173. Furthermore, because two arm portions 171b are formed, the valve stem 120 (i.e., the valve plate 110) is rotatable within the angular range sandwiched between these arm portions 171b.

[0040] The inner surface of the fixing nut 172 has a female thread that engages with the male thread formed on the valve stem 120. As a result, with the valve stem 120 inserted into the rotating plate 171, the fixing nut 172 is screwed onto the valve stem 120, which compresses the compression spring 160 and presses the detachable housing 152 against the exhaust pipe EP.

[0041] As shown in Figure 1, the stopper 173 is in contact with the arm portion 171b of the rotating plate 171, as well as with the tip portion of the other end of the compression spring 160.

[0042] <3. Effects> As described above, with the butterfly valve 100 of this embodiment, a sealing bush 141, which is separate from the support bush 142 of the bearing unit 140, contacts the housing 150 (fixed-side housing 151, detachable-side housing 152) with its outer circumferential surface 141A, and also contacts the flange 121 of the valve stem 120 with the valve stem opposing surface 141B of the sealing bush 141. This seals the space between the housing 150 and the bearing unit 140, and also seals the space between the valve stem 120 and the bearing unit 140. Therefore, it is possible to prevent exhaust gas EG flowing inside the exhaust pipe EP from leaking out of the exhaust pipe EP through the housing 150. Furthermore, the support bush 142 of the bearing unit 140 is positioned between the housing 150 and the sealing bush 141 of the bearing unit 140, and the outer circumferential surface 142A of the support bush 142 abuts against the housing 150. As a result, the support bush 142 supports the radial load on the valve plate 110 caused by the exhaust gas EG flowing through the exhaust pipe EP. Therefore, even if a high load is applied to the valve plate 110 when the valve plate 110 blocks the exhaust pipe EP, deformation and abnormal friction of the sealing bush 141 can be prevented. Therefore, even under high back pressure, it is possible to prevent exhaust gas EG from leaking out of the exhaust pipe EP. In other words, since there is generally a trade-off between load-bearing capacity and sealing performance, the bearing unit 140 of the butterfly valve 100 in this embodiment is composed of two components to achieve both load-bearing capacity and sealing performance.

[0043] Furthermore, even if the sealing bush 141 and the flange 121 of the valve stem 120 become stuck together due to rust or the like, the sealing bush 141 and the support bush 142 will continue to slide against each other, while the outer surface 141A of the sealing bush 141 and the housing 150 will continue to slide against each other, allowing the butterfly valve to continue to function. Furthermore, because the sealing bush 141 seals the space between itself and the housing 150, condensed water from inside the exhaust pipe EP is less likely to enter the support bush 142, thus making it less likely for rust to form on the support bush 142.

[0044] Furthermore, because the sealing bush 141 of the bearing unit 140 is softer than the support bush 142 of the bearing unit 140, the sealing bush 141 is more likely to deform to conform to the shape of the housing 150 or the flange 121 of the valve stem 120 compared to the case where the sealing bush 141 is harder than the support bush 142. Furthermore, because the inner diameter φs of the sealing bush 141 is greater than or equal to the inner diameter φb of the support bush 142, the valve stem 120 comes into contact with the inner surface of the support bush 142, which is harder than the sealing bush 141, before it comes into contact with the inner surface of the sealing bush 141. Therefore, even under high back pressure, leakage of exhaust gas EG to the outside of the exhaust pipe EP can be reliably prevented.

[0045] Furthermore, because the axial length Lb of the support bush 142 is longer than the axial length Ls of the sealing bush 141, the surface pressure applied to the support bush 142 when a high load is applied to the valve plate 110 while the valve plate 110 is blocking the exhaust pipe EP is reduced compared to the case where the axial length Lb of the support bush 142 is shorter than the axial length Ls of the sealing bush 141. This further improves the radial load resistance performance of the bearing unit 140.

[0046] Furthermore, the sealing bush 141 is formed from a mesh-like metal aggregate 141a woven from stainless steel wire, and graphite 141b filled in the metal aggregate 141a. Since the metal aggregate 141a is formed in a state where it is repeatedly bent in the axial direction of the sealing bush 141, the sealing bush 141 expands more easily in the axial direction than in the radial direction, increasing the axial cushioning of the sealing bush 141. This further improves the sealing performance between the sealing bush 141 and the flange 121 of the valve stem 120. Furthermore, as shown in Figure 4, the exposure of graphite 141b, which has a lower coefficient of friction than the metal aggregate 141a, on the surface of the sealing bush 141 results in a lower torque for rotating the valve stem 120, allowing for a smaller valve stem drive actuator. Furthermore, because the metal frame 141a is woven with stainless steel wire, the sealing bush 141 gains cushioning properties. This makes it less likely for the sealing bush 141 to be worn down when it is pressed into the housing 150, allows for stable support of the valve stem 120 even if it is slightly tilted, and absorbs vibrations in response to vertical vibrations during the operation of the four-wheeled vehicle. [Examples]

[0047] Next, a butterfly valve 200, which is a second embodiment of the present invention, will be described based on Figure 5, which is an enlarged cross-sectional view of the main part of the butterfly valve, which is a second embodiment of the present invention. Furthermore, the butterfly valve 200 of the second embodiment is a modified version of the bearing unit 140 in the butterfly valve 100 of the first embodiment, and since many elements are common to the butterfly valve 100 of the first embodiment, detailed explanations of the common items will be omitted, and only a code in the 200s, with the last two digits being common, will be assigned.

[0048] As shown in Figure 5, in the bearing unit 240 of the second embodiment, the support bush opposing surface 241C of the sealing bush 241 is inclined toward the central axis C of the valve stem 220 and toward the flange 221 of the valve stem 220. The support bush opposing surface 241C may be inclined toward the central axis C of the valve stem 220 and toward the flange 221 of the valve stem 220.

[0049] The sealing bushing-facing surface 242C of the support bushing 242 is also inclined toward the central axis C of the valve stem 220, corresponding to the support bushing-facing surface 241C of the sealing bushing 241.

[0050] In the butterfly valve 200 of the second embodiment formed in this manner, the supporting bush-facing surface 241C of the sealing bush 241 and the sealing bush-facing surface 242C of the supporting bush 242 are inclined to correspond to each other, which facilitates radial positioning of the sealing bush 241 and the supporting bush 242, and thus allows for efficient assembly of the bearing unit 240. [Examples]

[0051] Next, a butterfly valve 300, which is a third embodiment of the present invention, will be described based on Figure 6, which is an enlarged cross-sectional view of the main part of the butterfly valve, which is a third embodiment of the present invention. Furthermore, the butterfly valve 300 of the third embodiment is a modified version of the butterfly valve 100 of the first embodiment, with changes to the shape of the valve stem 120 and bearing unit 140. Since many elements are common to the butterfly valve 100 of the first embodiment, detailed explanations of common items are omitted, and only a 300-series code, with the last two digits being common, is assigned.

[0052] As shown in Figure 6, the sealing bush contact surface 321A of the flange 321 of the valve stem 320 in the third embodiment is inclined toward the central axis C of the valve stem 320 and toward the exhaust pipe EP. The sealing bush contact surface 321A may be inclined in a direction toward the valve stem 320 and toward the exhaust pipe EP.

[0053] The valve stem opposing surface 341B of the sealing bush 341 is also inclined toward the central axis C of the valve stem 320, corresponding to the sealing bush contact surface 321A of the valve stem 320.

[0054] In the third embodiment of the butterfly valve 300 formed in this manner, the valve stem 320 is positioned relative to the bearing unit 340 because the sealing bush contact surface 321A of the valve stem 320 and the valve stem opposing surface 341B of the sealing bush 341 are inclined to correspond to each other. This ensures that the space between the valve stem 320 and the bearing unit 340 is reliably sealed and the valve stem 320 is reliably supported. [Examples]

[0055] Next, a butterfly valve 400, which is a fourth embodiment of the present invention, will be described based on Figure 7, which is an enlarged cross-sectional view of the main part of the butterfly valve, which is a fourth embodiment of the present invention. Furthermore, the butterfly valve 400 of the fourth embodiment is a modified version of the butterfly valve 100 of the first embodiment, with changes to the shape of the valve stem 120 and bearing unit 140. Since many elements are common to the butterfly valve 100 of the first embodiment, detailed explanations of common items are omitted, and only a code in the 400s, with the last two digits being common, is assigned.

[0056] As shown in Figure 7, in the fourth embodiment, the sealing bush contact surface 421A of the flange 421 of the valve stem 420 is inclined toward the central axis C of the valve stem 420 and toward the exhaust pipe EP.

[0057] The valve stem opposing surface 441B of the sealing bush 441 is also inclined toward the central axis C of the valve stem 420, corresponding to the sealing bush contact surface 421A of the valve stem 420. Furthermore, the support bush opposing surface 441C of the sealing bush 441 is inclined toward the central axis C of the valve stem 420 and toward the flange 421 of the valve stem 420. Furthermore, the inclination angle of the valve stem opposing surface 441B of the sealing bush 441 is equal to the inclination angle of the support bush opposing surface 441C of the sealing bush 441.

[0058] The sealing bush opposing surface 442C of the support bush 442 is also inclined toward the central axis C of the valve stem 420, corresponding to the support bush opposing surface 441C of the sealing bush 441.

[0059] The sealing bush contact surface 421A of the valve stem 420 may be inclined in a direction toward the valve stem 420 and toward the exhaust pipe EP. Furthermore, the support bush-facing surface 441C of the sealing bush 441 may be inclined toward the central axis C of the valve stem 420 and toward away from the flange 421 of the valve stem 420.

[0060] In the butterfly valve 400 of the fourth embodiment formed in this way, the supporting bush opposing surface 441C of the sealing bush 441 and the sealing bush opposing surface 442C of the supporting bush 442 are inclined to correspond to each other, which facilitates radial positioning of the sealing bush 441 and the supporting bush 442, and thus allows for efficient assembly of the bearing unit 240. Furthermore, because the sealing bush contact surface 421A of the valve stem 420 and the valve stem opposing surface 441B of the sealing bush 441 are inclined to correspond to each other, the valve stem 420 is positioned relative to the bearing unit 440, thereby ensuring a secure seal between the valve stem 420 and the bearing unit 440, and also ensuring the valve stem 420 is securely supported. Furthermore, since the inclination angle of the valve stem opposing surface 441B of the sealing bush 441 is equal to the inclination angle of the support bush opposing surface 441C of the sealing bush 441, the axial directionality of the sealing bush 441 is eliminated, thereby suppressing incorrect assembly of the sealing bush 441. [Examples]

[0061] Next, a fifth embodiment of the present invention, a butterfly valve 500, will be described based on Figures 8A and 8B. Figure 8A is an enlarged cross-sectional view of the main part of a butterfly valve, which is a fifth embodiment of the present invention, and Figure 8B is an enlarged view of IIIVB of Figure 8A. Furthermore, the butterfly valve 500 of the fifth embodiment is a modified version of the bearing unit 140 in the butterfly valve 100 of the first embodiment, and since many elements are common to the butterfly valve 100 of the first embodiment, detailed explanations of the common items are omitted, and only a code in the 500s, with the last two digits being common, is assigned.

[0062] As shown in Figure 8A, in the fifth embodiment of the bearing unit 540, the support bush 542 is inserted into the sealing bush 541.

[0063] <1. Sealing bushing> The sealing bush 541 is formed from a cylindrical base 541c and a cylindrical projection 541d that protrudes axially from the base 541c.

[0064] As shown in Figure 8A, the outer circumferential surface 541d1 of the protruding portion 541d is flush with the outer circumferential surface 541c1 of the base portion 541c. Furthermore, the inner diameter φs1 of the protruding portion 541d is larger than the inner diameter φs of the base portion 541c, as shown in Figure 8A. Furthermore, as shown in Figure 8A, the axial length Ls1 of the protruding portion 541d is greater than the axial length Ls of the base portion 541c.

[0065] Furthermore, in this embodiment, as shown in Figure 8B, the sealing bush 541 has a portion of the metal aggregate 541a exposed on the inner diameter side. Therefore, the support bush 542, which is inserted into the sealing bush 541, engages with the metal frame 541a of the sealing bush 541.

[0066] <2. Support bushings> The support bush 542 is formed from a cylindrical base 542a and a cylindrical projection 542b that protrudes axially from the base 542a.

[0067] The inner circumferential surface 542b1 of the protruding portion 542b is flush with the inner circumferential surface 542a1 of the base portion 542a. In other words, as shown in Figure 8A, the inner diameter φb of the protruding portion 542b is equal to the inner diameter of the base portion 542a and slightly smaller than the inner diameter φs of the sealing bush 541.

[0068] As shown in Figure 8A, the outer diameter φbo1 of the protruding portion 542b is smaller than the outer diameter φbo of the base portion 542a. Furthermore, the outer diameter φbo1 of the protrusion 542b is approximately equal to the inner diameter φs1 of the protrusion 541d of the sealing bush 541, as shown in Figure 8A.

[0069] As shown in Figure 8A, the axial length Lb1 of the protrusion 542b is greater than the axial length Lb2 of the base 542a. Furthermore, the axial length Lb1 of the protrusion 542b is approximately equal to the axial length Ls1 of the protrusion 541d of the sealing bush 541, as shown in Figure 8A.

[0070] In this embodiment, the protrusion 542b of the support bush 542 was located closer to the valve stem 520 than the protrusion 541d of the sealing bush 541, but the protrusion 541d of the sealing bush 541 may also be located closer to the valve stem 520 than the protrusion 542b of the support bush 542.

[0071] In the fifth embodiment of the butterfly valve 500 formed in this way, the support bush 542 is inserted into the sealing bush 541, making the bearing unit 540 easier to handle as a single integrated component, thus allowing for efficient assembly of the butterfly valve 500. [Examples]

[0072] Next, a butterfly valve 600, which is a sixth embodiment of the present invention, will be described based on Figures 9A and 9B. Figure 9A is an exploded perspective view of the bearing unit in a butterfly valve according to the sixth embodiment of the present invention, and Figure 9B is an enlarged cross-sectional view of the main part of the butterfly valve in the IXB-IXB section of Figure 9A. Furthermore, the butterfly valve 600 of the sixth embodiment is a further modification of the shape of the bearing unit 540 in the butterfly valve 500 of the fifth embodiment, and since many elements are common with the butterfly valve 500 of the fifth embodiment, detailed explanations of the common items will be omitted, and only a code in the 600s, with the last two digits being common, will be assigned.

[0073] As shown in Figure 9A, in the bearing unit 640 of the sixth embodiment, a ridge 641d2 is provided protruding from the inner circumferential surface of the projection 641d of the sealing bush 641. When inserting the support bush 642 into the sealing bush 641, since the sealing bush 641 is softer than the support bush 642, as shown in Figure 9B, when the support bush 642 is inserted into the sealing bush 641, the protrusion 641d2 of the sealing bush 641 is crushed, and the support bush 642 comes into contact with a part of the sealing bush 641.

[0074] In the sixth embodiment of the butterfly valve 600 formed in this manner, the projection 641d2 is formed on the sealing bush 641. Since the projection 641d2 acts as an insertion guide when inserting the support bush 642 into the sealing bush 641, not only is the ease of assembly of the bearing unit 640 improved, but even if the sealing bush 641 becomes fixed to the flange 621 of the valve stem 620, the sealed bush 641 fixed to the valve stem 620 slides against the support bush 642, thus maintaining the function of the butterfly valve over a long period of time.

[0075] <Variation> Although the butterfly valves described above are embodiments of the present invention, the butterfly valves of the present invention are not limited to the butterfly valves of the embodiments described above.

[0076] For example, in the embodiment described above, the metal frame was woven from stainless steel wire, but any metal wire can be used as long as it is woven from metal wire. However, in order to reliably seal the space between the housing and the sealing bush, it is preferable that the metal frame be woven from metal wire having a coefficient of thermal expansion similar to that of the housing material.

[0077] For example, in the embodiment described above, the valve plate was provided upstream of the valve stem, but the position of the valve plate is not limited to this, and it may also be provided downstream of the valve stem.

[0078] For example, in the embodiment described above, the support bush was made of the same stainless steel as the housing, but the material of the support bush is not limited to this, and may be made of, for example, hard carbon or ceramics. [Explanation of symbols]

[0079] 100, 200, 300, 400, 500, 600... Butterfly valve 110 ··· Valve plate 120, 220, 320, 420, 520... Valve stem 121, 321, 421... Tsuba (sword guard) 321A, 421A... Sealing bush contact surface 130 ··· Connecting bolts 140, 240, 340, 440, 540... Bearing Units 141, 241, 341, 441, 541, 641... Sealing bushings 141A... Outer surface 141B, 341B, 441B... Valve shaft opposing surface 241C 441C ... Support bush opposing surface 141a, 541a... Metal aggregate 141b, 541b... Graphite 541c Base 541c1 ... Outer surface 541d, 641d... Protrusion 541d1 ··· Outer surface 641d2... protrusion 142, 242, 342, 442, 542, 642... Support bushings 142A... Outer surface 242C 442C ... Sealing bush opposing surface 542a Base 542a1 ··· Inner peripheral surface 542b... Protrusion 542b1 ··· Inner peripheral surface 150 ··· Housing 151 ··· Fixed side housing 152 ··· Detachable housing 160 ··· Compression spring 170 ··· Valve shaft rotation mechanism 171 ··· Rotating plate 171a ··· Spring retainer 171b... Arm 172 ··· Fixing nut 173 ··· Stopper EP... Exhaust pipe EP1...Shaft insertion hole EG... Exhaust gas C ··· The central axis of the valve stem φF ··· Diameter of the guard φi ··· Inner diameter of the housing φP ··· Diameter of the shaft insertion hole in the exhaust pipe φs ··· Inner diameter of the sealing bush (base) φs1 ··· Inner diameter of the protruding part of the sealing bush φb ··· Inner diameter of the support bush (protruding part) φbo ··· Outer diameter of the support bush (base) φbo1 ··· Outer diameter of the protruding part of the support bush φh ··· Diameter of the through-hole in the detachable housing φd ··· Diameter of the valve stem Ls ··· Axial length of the sealing bush (base) Ls1... Axial length of the sealing bush (protrusion) Lb... Axial length of the support bush Lb1... Axial length of the support bush (projection) Ls2... Axial length of the sealing bush (base)

Claims

1. A butterfly valve that opens and closes an exhaust pipe that communicates with the exhaust port of an engine, A valve plate provided inside the exhaust pipe, A valve stem that crosses the exhaust pipe and holds the valve plate, A bearing unit that slidably supports the valve shaft, having a separate annular sealing bush and a support bush into which the valve shaft is inserted, The system comprises a housing that is attached to the exhaust pipe and houses the bearing unit located outside the exhaust pipe, The support bush of the bearing unit is positioned between the housing and the sealing bush of the bearing unit, and the outer circumferential surface of the support bush abuts against the housing. The sealing bush of the bearing unit slidably contacts the housing with its outer circumferential surface and contacts the flange of the valve shaft with the valve shaft facing surface of the sealing bush. A butterfly valve characterized in that the sealing bush of the bearing unit slides against the housing on its outer circumferential surface when the sealing bush and the flange of the valve shaft are fixed together.

2. The sealing bush of the bearing unit is softer than the support bush of the bearing unit. The butterfly valve according to claim 1, characterized in that the inner diameter of the sealing bush is greater than or equal to the inner diameter of the support bush.

3. A gap is formed between the support bush and the valve shaft, The butterfly valve according to claim 1, characterized in that the inner diameter of the sealing bush is larger than the inner diameter of the support bush.

4. The butterfly valve according to any one of claims 1 to 3, characterized in that the coefficient of linear expansion of the support bush and the coefficient of linear expansion of the housing are substantially the same.

Images