BUTTERFLY VALVE

Abstract

Proposed is a butterfly valve for minimizing leak of exhaust gas from an exhaust pipe even under high back pressure. The butterfly valve may include a valve plate provided in the exhaust pipe, a valve shaft crossing the exhaust pipe and holding the valve plate, and a bearing unit slidably supporting the valve shaft and including an annular sealing bush and an annular support bush into which the valve shaft 120 is inserted. The valve may also include a housing attached to the exhaust pipe and accommodating the bearing unit. The support bush is arranged between the housing and the sealing bush and contacts the housing on an outer peripheral surface of the support bush. The sealing bush contacts the housing on an outer peripheral surface of the sealing bush and contacts a flange of the valve shaft on a valve shaft opposing surface of the sealing bush.

Claims

1. A butterfly valve for opening and closing an exhaust pipe communicating with an exhaust port of an engine, the butterfly valve comprising: a valve plate provided in the exhaust pipe; a valve shaft configured to cross the exhaust pipe and hold the valve plate; a bearing unit comprising an annular sealing bush and an annular support bush, which are separate components and into which the valve shaft is inserted, the bearing unit configured to slidably support the valve shaft; and a housing attached to the exhaust pipe and configured to accommodate the bearing unit arranged outside the exhaust pipe, wherein the support bush of the bearing unit is arranged between the housing and the sealing bush of the bearing unit and is in contact with the housing on an outer peripheral surface of the support bush, and wherein the sealing bush of the bearing unit is in contact with the housing on an outer peripheral surface of the sealing bush and is in contact with a flange of the valve shaft on a valve shaft opposing surface of the sealing bush.

2. The butterfly valve according to claim 1, wherein the sealing bush of the bearing unit is softer than the support bush of the bearing unit, and wherein an inner diameter of the sealing bush is larger than or equal to an inner diameter of the support bush.

3. The butterfly valve according to claim 1, wherein axial length of the support bush is longer than axial length of the sealing bush.

4. The butterfly valve according to claim 1, wherein the sealing bush is formed from mesh-like metal aggregate woven with metal wires and graphite filled in the metal aggregate, and wherein the metal aggregate is repeatedly bent in the axial direction of the sealing bush.

5. The butterfly valve according to claim 2, wherein axial length of the support bush is longer than axial length of the sealing bush.

6. The butterfly valve according to claim 2, wherein the sealing bush is formed from mesh-like metal aggregate woven with metal wires and graphite filled in the metal aggregate, and wherein the metal aggregate is repeatedly bent in the axial direction of the sealing bush.

7. The butterfly valve according to claim 3, wherein the sealing bush is formed from mesh-like metal aggregate woven with metal wires and graphite filled in the metal aggregate, and wherein the metal aggregate is repeatedly bent in the axial direction of the sealing bush.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0020] FIG. 1 is a perspective view of an exhaust pipe incorporating a butterfly valve according to the first example of the present invention.

[0021] FIG. 2 is a longitudinal cross-sectional view of FIG. 1.

[0022] FIG. 3 is an enlarged view of part III in FIG. 2.

[0023] FIG. 4 is an enlarged view of part IV in FIG. 3.

[0024] FIG. 5 is an enlarged sectional view of a main part of a butterfly valve according to the second example of the present invention.

[0025] FIG. 6 is an enlarged sectional view of a main part of a butterfly valve according to the third example of the present invention.

[0026] FIG. 7 is an enlarged sectional view of a main part of a butterfly valve according to the fourth example of the present invention.

[0027] FIG. 8A is an enlarged sectional view of a main part of a butterfly valve according to the fifth example of the present invention.

[0028] FIG. 8B is an enlarged view of part VIIIB in FIG. 8A.

[0029] FIG. 9A is an exploded perspective view of a bearing unit in a butterfly valve according to the sixth example of the present invention.

[0030] FIG. 9B is an enlarged sectional view of a main part of the butterfly valve taken along the IXB-IXB cross section in FIG. 9A.

DESCRIPTION OF EMBODIMENTS

[0031] The specific embodiment of a butterfly valve in the present invention may be arbitrary as long as a butterfly valve that opens and closes an exhaust pipe communicating with an exhaust port of an engine comprises: a valve plate provided in the exhaust pipe; a valve shaft that crosses the exhaust pipe and holds the valve plate; a bearing unit that has an annular sealing bush and an annular support bush, which are separate components and into which the valve shaft is inserted, and slidably supports the valve shaft; and a housing that is attached to the exhaust pipe and accommodates the bearing unit arranged outside the exhaust pipe, wherein the support bush of the bearing unit is arranged between the housing and the sealing bush of the bearing unit and is in contact with the housing on an outer peripheral surface of the support bush, and wherein the sealing bush of the bearing unit is in contact with the housing on an outer peripheral surface of the sealing bush and is in contact with a flange of the valve shaft on a valve shaft opposing surface of the sealing bush, and thereby, with this butterfly valve, exhaust gas is hard to leak out of the exhaust pipe even under high back pressure.

[0032] For example, the butterfly valve in the present invention is provided in an exhaust pipe communicating with the exhaust port of an engine of an automatic four-wheeled vehicle. However, the butterfly valve of the present invention may be provided not only in an automatic four-wheeled vehicle but also in an automatic two-wheeled vehicle, and the automatic four-wheeled vehicle may be a gasoline vehicle or a diesel vehicle.

[0033] That is, the engine with which the exhaust pipe communicates may be a gasoline engine or a diesel engine.

[0034] Here, diesel engines used in trucks generally have higher back pressure than gasoline engines used in passenger cars. However, the butterfly valve according to the present invention can sufficiently suppress leakage of exhaust gas out of the exhaust pipe.

Example 1

[0035] Hereinafter, a butterfly valve 100 according to the first example of the present invention will be described below based on FIGS. 1 to 4.

<1. Installation Environment of Butterfly Valve>

[0036] First, the environment in which the butterfly valve 100 is installed will be described based on FIG. 1, which is a perspective view of an exhaust pipe incorporating a butterfly valve according to the first example of the present invention.

[0037] The butterfly valve 100 of the present example opens and closes an exhaust pipe EP communicating with an exhaust port (not shown) of a diesel engine of an automatic four-wheeled vehicle, and is arranged in the middle of the cylindrical exhaust pipe EP as shown in FIG. 1.

<2. Structure of Butterfly Valve>

[0038] Next, the structure of the butterfly valve 100 will be described based on FIGS. 1 to 4.

[0039] FIG. 2 is a longitudinal cross-sectional view of FIG. 1, FIG. 3 is an enlarged view of part III in FIG. 2, and FIG. 4 is an enlarged view of part IV in FIG. 3.

<2.1. Main Configuration of Butterfly Valve>

[0040] As shown in FIGS. 1 and 2, the butterfly valve 100 includes a disk-shaped valve plate 110 provided in the exhaust pipe EP, a valve shaft 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 shaft 120, a bearing unit 140 that slidably supports the valve shaft 120, and a housing 150 that is attached to the exhaust pipe E and accommodates the bearing unit 140 arranged outside the exhaust pipe EP.

<2.1.1. Valve Plate>

[0041] The valve plate 110 is provided on the upstream side of the valve shaft 120, as shown in FIG. 2.

[0042] Thereby, even if the back pressure of exhaust gas EG is applied to the valve plate 110, the valve plate 110 is pressed against the valve shaft 120, so that the valve plate 110 is hard to detach from the valve shaft 120.

<2.1.2. Valve Shaft>

[0043] As shown in FIG. 2, flanges 121 are formed at both ends of the valve shaft 120 and protrude in the radial direction.

[0044] As shown in FIG. 3, a diameter F of the flange 121 is smaller than a diameter P of a shaft insertion hole EP1 formed in the exhaust pipe EP.

[0045] Further, as shown in FIG. 3, the diameter of the valve shaft 120 outward from the flange 121 is constant up to the end.

[0046] Furthermore, a male thread is formed at one end (upper end in FIG. 2) of the valve shaft 120.

<2.1.3 Bearing Unit>

[0047] As shown in FIG. 2, the bearing unit 140 consists of an annular sealing bush 141 and an annular support bush 142, into which the valve shaft 120 is inserted.

[0048] As shown in FIGS. 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, the Young's modulus of the sealing bush 141 is 0.15 to 0.5 GPa or more, Poisson's ratio is approximately 0.2 to 0.3, and compressive strength is 46 MPa or less).

[0049] The sealing bush 141 is in pressure contact with the housing 150 on an outer peripheral surface 141A and is in contact with the flange 121 of the valve shaft 120 on a valve shaft opposing surface 141B.

[0050] 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 shaft 120 is also sealed.

[0051] Further, an inner diameter s of the sealing bush 141 is slightly larger than an inner diameter b of the support bush 142.

[0052] Here, the inner diameter s of the sealing bush 141 may be equal to the inner diameter b of the support bush 142.

[0053] As shown in FIG. 4, the sealing bush 141 is formed from mesh-like metal aggregate 141a woven with metal wires (stainless wires in the present example) and graphite 141b filled in the metal aggregate 141a.

[0054] The metal aggregate 141a is repeatedly bent in the axial direction of the sealing bush 141 (that is, the direction in which the valve shaft 120 extends; the upper-lower direction in FIG. 4).

[0055] Therefore, the metal aggregate 141a easily expands in the axial direction.

[0056] The graphite 141b is expanded graphite in order to easily enter gaps in the metal aggregate 141a.

[0057] In the present example, the support bush 142 is made of stainless steel as the housing 150 is, and has substantially the same linear expansion coefficient as the housing 150.

[0058] Thereby, when the butterfly valve 100 becomes high temperature due to exhaust gas or the like, the support bush 142 also expands as well as the housing 150, so that the space between the support bush 142 and the housing 150 can be kept sealed.

[0059] As shown in FIGS. 2 and 3, the support bush 142 is arranged between the housing 150 and the sealing bush 141 and is in pressure contact with the housing 150 on an outer peripheral surface 142A.

[0060] Further, an axial length Lb of the support bush 142 is longer than an axial length Ls of the sealing bush 141.

<2.1.4 Housing>

[0061] The housing 150 is a component that covers the shaft insertion hole EP1 of the exhaust pipe EP, and as shown in FIG. 2, consists of a cylindrical fixed side housing 151 with a flange and a bottom, which is attached to the lower side of the exhaust pipe EP, and a cylindrical detachable side housing 152 with a flange and a bottom, which is attached to the upper side of the exhaust pipe EP.

[0062] The fixed side housing 151 is integrated with the exhaust pipe EP by welding or the like so that the exhaust gas EG does not leak from the space between the fixed side housing 151 and the exhaust pipe EP.

[0063] The detachable side housing 152 is in contact with the exhaust pipe EP, and as shown in FIG. 3, a through hole 152a through which the valve shaft 120 is inserted is formed in the bottom surface.

[0064] As shown in FIG. 3, a diameter h of the through hole 152a is slightly larger than a diameter od of the valve shaft 120.

[0065] Further, as shown in FIG. 3, the inner diameter of the housing 150 (that is, the inner diameter of the fixed side housing 151 and the inner diameter of the detachable side housing 152) pi is slightly larger than the diameter F of the flange 121 of the valve shaft 120 and is smaller than the diameter P of the shaft insertion hole EP1 of the exhaust pipe EP.

<2.2. Other Configurations of Butterfly Valve>

[0066] Further, the butterfly valve 100 includes a coiled pressing spring 160 that presses the detachable side housing 152 against the exhaust pipe EP, and a valve shaft rotation mechanism 170 that rotates the valve shaft 120.

<2.2.1 Pressing Spring>

[0067] As shown in FIG. 2, the pressing spring 160 is a torsion coil spring, is arranged between the detachable side housing 152 and the valve shaft rotation mechanism 170, and biases the detachable side housing 152 toward the exhaust pipe EP.

[0068] Due to this pressing spring 160, the detachable side housing 152 is in contact with the exhaust pipe EP so that the exhaust gas EG does not leak from the space between the detachable side housing 152 and the exhaust pipe EP.

<2.2.2 Valve Shaft Rotation Mechanism

[0069] As shown in FIG. 1, the valve shaft rotation mechanism 170 includes an annular rotary plate 171 that is in contact with the other end of the pressing spring 160, a fixing nut 172 that fixes the rotary plate 171 to the valve shaft 120, and a stopper 173 that bends up from the exhaust pipe EP and stops rotation of the rotary plate 171 and a valve shaft drive actuator (not shown) that rotates the valve shaft 120.

[0070] Here, when the valve plate 110 closes the exhaust pipe EP as shown in FIG. 1, the pressing spring 160 is being twisted by the valve shaft drive actuator.

[0071] In other words, when the pressing spring 160 is not twisted, that is, when the valve shaft drive actuator is not operating, the valve plate 110 does not close the exhaust pipe EP, and the exhaust gas EG can freely flow through the exhaust pipe EP.

[0072] The rotary plate 171 rotates together with the valve shaft 120, and as shown in FIG. 1, includes a spring suppressing portion 171a, which bends down from the rotary plate 171 and is in contact with a tip portion on one end side of the pressing spring 160, and two arm portions 171b that come into contact with the stopper 173.

[0073] The spring suppressing portion 171a is L-shaped, and is in contact with the tip portion of one end of the pressing spring 160 on two sides.

[0074] The arm portion 171b is formed of a horizontal portion that extends in the horizontal direction and a bending-down portion that bends down from the tip of the horizontal portion and comes into contact with the stopper 173.

[0075] Here, since the two arm portions 171b are formed, the valve shaft 120 (that is, the valve plate 110) is rotatable within an angular range between the two arm portions 171b.

[0076] A female thread is formed on the inner surface of the fixing nut 172 and is screwed by a male thread formed on the valve shaft 120.

[0077] Thereby, by screwing the fixing nut 172 onto the valve shaft 120 in a state where the valve shaft 120 is inserted into the rotary plate 171, the pressing spring 160 is compressed and the detachable side housing 152 is pressed against the exhaust pipe EP.

[0078] As shown in FIG. 1, the stopper 173 is in contact with not only the arm portion 171b of the rotary plate 171 but also the tip portion of the other end of the pressing spring 160.

<3. Effect:

[0079] According to the butterfly valve 100 of the present example described above, the sealing bush 141, which is a separate component from the support bush 142 of the bearing unit 140, is contact with the housing 150 (fixed side housing 151, detachable side housing 152) on the outer peripheral surface 141A of the sealing bush 141 and is in contact with the flange 121 of the valve shaft 120 at the valve shaft opposing surface 141B of the sealing bush 141. Thereby, since the space between the housing 150 and the bearing unit 140 is sealed and the space between the valve shaft 120 and the bearing unit 140 is also sealed, it is possible to prevent the exhaust gas EG flowing inside the exhaust pipe EP from leaking out of the exhaust pipe EP via the housing 150.

[0080] Further, the support bush 142 of the bearing unit 140 is arranged between the housing 150 and the sealing bush 141 of the bearing unit 140 and is in contact with the housing 150 on the outer peripheral surface 142A of the support bush 142. Thereby, since the support bush 142 supports the radial load on the valve plate 110 caused by the exhaust gas EG flowing in the exhaust pipe EP, even if a high load is applied to the valve plate 110 when the valve plate 110 closes the exhaust pipe EP, it is possible to prevent deformation, abnormal friction and the like of the sealing bush 141.

[0081] Therefore, even under high back pressure, it is possible to prevent the exhaust gas EG from leaking out of the exhaust pipe EP.

[0082] That is, although there is generally a trade-off relationship between load-bearing performance and sealing performance, by adopting the configuration in which the bearing unit 140 is consisted of two components as in the butterfly valve 100 of the present example, load-bearing performance and sealing performance can be both achieved.

[0083] Further, even if the sealing bush 141 and the flange 121 of the valve shaft 120 are stuck together due to rust or the like, since the outer peripheral surface 141A of the sealing bush 141 and the housing 150 slide while the sealing bush 141 and the support bush 142 slide, this butterfly valve can continue to function.

[0084] Further, the sealing bush 141 seals the space between the exhaust pipe EP and the housing 150. Thereby, since condensed water in the exhaust pipe EP is less likely to enter the support bush 142, the support bush 142 is less likely to rust.

[0085] Further, the sealing bush 141 of the bearing unit 140 is softer than the support bush 142 of the bearing unit 140. Thereby, compared to the case where the sealing bush 141 is harder than the support bush 142, the sealing bush 141 easily deforms by following the shape of the housing 150 or the flange 121 of the valve shaft 120.

[0086] Further, the inner diameter s of the sealing bush 141 is larger than or equal to the inner diameter b of the support bush 142. Thereby, the valve shaft 120 comes into contact with the inner peripheral surface of the support bush 142 that is harder than the sealing bush 141 before coming into contact with the inner peripheral surface of the sealing bush 141.

[0087] Therefore, even under high back pressure, it is possible to reliably prevent the exhaust gas EG from leaking out of the exhaust pipe EP.

[0088] Further, the axial length Lb of the support bush 142 is longer than the axial length Ls of the sealing bush 141. Thereby, 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, since the surface pressure applied to the support bush 142 is reduced when a high load is applied to the valve plate 110 in a state where the valve plate 110 closes the exhaust pipe EP, it is possible to further improve the radial load resistance performance of the bearing unit 140.

[0089] Further, the sealing bush 141 is formed from the mesh-like metal aggregate 141a woven with metal wires (stainless steel wires) and the graphite 141b filled in the metal aggregate 141a, and the metal aggregate 141a is repeatedly bent in the axial direction of the sealing bush 141. Thereby, since the sealing bush 141 expands more easily in the axial direction than in the radial direction and the cushioning properties of the sealing bush 141 in the axial direction are improved, it is possible to further improve the sealing performance between the sealing bush 141 and the flange 121 of the valve shaft 120.

[0090] Further, as shown in FIG. 4, the graphite 141b, which has a smaller friction coefficient than the metal aggregate 141a, is exposed on the surface of the sealing bush 141. Thereby, the torque for rotating the valve shaft 120 is reduced, and it is possible to downsize the shaft drive actuator.

[0091] Further, the metal aggregate 141a is woven with stainless steel wires. Thereby, since the sealing bush 141 has cushioning properties, the sealing bush 141 is less likely to be shaved when the sealing bush 141 is press-fitted into the housing 150, and even if the valve shaft 120 is slightly tilted, the valve shaft 120 can be stably supported and vertical vibrations can be absorbed when the automatic four-wheeled vehicle is running.

Example 2

[0092] Next, a butterfly valve 200 according to the second example of the present invention will be described based on FIG. 5, which is an enlarged sectional view of a main part of a butterfly valve according to the second example of the present invention.

[0093] Here, the butterfly valve 200 in the second example is a butterfly valve in which the shape of the bearing unit 140 in the butterfly valve 100 in the first example is modified, and has many components in common with the butterfly valve 100 in the first example. Thus, detailed explanation of common components will be omitted, and only 200-series signs with the same last two digits will be given.

[0094] As shown in FIG. 5, in a bearing unit 240 in the second example, a support bush opposing surface 241C of a sealing bush 241 is inclined in the direction toward a central axis C of a valve shaft 220 and in the direction toward a flange 221 of the valve shaft 220.

[0095] Here, the support bush opposing surface 241C may be inclined in the direction toward the central axis C of the valve shaft 220 and in the direction away from the flange 221 of the valve shaft 220.

[0096] A sealing bush opposing surface 242C of a support bush 242 is also inclined toward the central axis C of the valve shaft 220 in correspondence with the support bush opposing surface 241C of the sealing bush 241.

[0097] The butterfly valve 200 formed in this way in the second example has the structure in which the support bush opposing surface 241C of the sealing bush 241 and the sealing bush opposing surface 242C of the support bush 242 are inclined in correspondence with each other. Thereby, since the sealing bush 241 and the support bush 242 can be easily positioned in the radial direction, it is possible to efficiently assemble the bearing unit 240.

Example 3

[0098] Next, a butterfly valve 300 according to the third example of the present invention will be described based on FIG. 6, which is an enlarged sectional view of a main part of a butterfly valve according to the third example of the present invention.

[0099] Here, the butterfly valve 300 in the third example is a butterfly valve in which the shapes of the valve shaft 120 and the bearing unit 140 in the butterfly valve 100 in the first example are modified, and has many components in common with the butterfly valve 100 in the first example. Thus, detailed explanation of common components will be omitted, and only 300-series signs with the same last two digits will be given.

[0100] As shown in FIG. 6, a sealing bush contact surface 321A of a flange 321 of a valve shaft 320 in the third example is inclined in the direction toward the central axis C of the valve shaft 320 and in the direction away from the exhaust pipe EP.

[0101] Here, the sealing bush contact surface 321A may be inclined in the direction toward the valve shaft 320 and in the direction approaching to the exhaust pipe EP.

[0102] A valve shaft opposing surface 341B of a sealing bush 341 is also inclined toward the central axis C of the valve shaft 320 in correspondence with the sealing bush contact surface 321A of the valve shaft 320.

[0103] The butterfly valve 300 formed in this way in the third example has the structure in which the sealing bush contact surface 321A of the valve shaft 320 and the valve shaft opposing surface 341B of the sealing bush 341 are inclined in correspondence with each other. Thereby, since the valve shaft 320 is positioned relative to a bearing unit 340, it is possible to reliably seal the space between the valve shaft 320 and the bearing unit 340 and reliably support the valve shaft 320.

Example 4

[0104] Next, a butterfly valve 400 according to the fourth example of the present invention will be described based on FIG. 7, which is an enlarged sectional view of a main part of a butterfly valve according to the fourth example of the present invention.

[0105] Here, the butterfly valve 400 in the fourth example is a butterfly valve in which the shapes of the valve shaft 120 and the bearing unit 140 in the butterfly valve 100 in the first example are modified, and has many components in common with the butterfly valve 100 in the first example. Thus, detailed explanation of common components will be omitted, and only 400-series signs with the same last two digits will be given.

[0106] As shown in FIG. 7, a sealing bush contact surface 421A of a flange 421 of a valve shaft 420 in the fourth example is inclined in the direction toward the central axis C of the valve shaft 420 and in the direction away from the exhaust pipe EP.

[0107] A valve shaft opposing surface 441B of a sealing bush 441 is also inclined toward the central axis C of the valve shaft 420 in correspondence with the sealing bush contact surface 421A of the valve shaft 420.

[0108] Further, a support bush opposing surface 441C of the sealing bush 441 is inclined in the direction toward the central axis C of the valve shaft 420 and in the direction toward the flange 421 of the valve shaft 420.

[0109] Here, the inclination angle of the valve shaft 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.

[0110] A sealing bush opposing surface 442C of a support bush 442 is also inclined toward the central axis C of the valve shaft 420 in correspondence with the support bush opposing surface 441C of the sealing bush 441.

[0111] Here, the sealing bush contact surface 421A of the valve shaft 420 may be inclined in the direction toward the valve shaft 420 and in the direction approaching to the exhaust pipe EP.

[0112] Further, the support bush opposing surface 441C of the sealing bush 441 may be inclined in the direction toward the central axis C of the valve shaft 420 and in the direction away from the flange 421 of the valve shaft 420.

[0113] The butterfly valve 400 formed in this way in the fourth example has the structure in which the support bush opposing surface 441C of the sealing bush 441 and the sealing bush opposing surface 442C of the support bush 442 are inclined in correspondence with each other. Thereby, since the sealing bush 441 and the support bush 442 can be easily positioned in the radial direction, it is possible to efficiently assemble the bearing unit 440.

[0114] Further, the sealing bush contact surface 421A of the valve shaft 420 and the valve shaft opposing surface 441B of the sealing bush 441 are inclined in correspondence with each other. Thereby, since the valve shaft 420 is positioned relative to a bearing unit 440, it is possible to reliably seal the space between the valve shaft 420 and the bearing unit 440 and reliably support the valve shaft 420.

[0115] Further, the inclination angle of the valve shaft 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. Thereby, since the axial directionality of the sealing bush 441 is eliminated, it is possible to suppress incorrect assembly of the sealing bush 441.

Example 5

[0116] Next, a butterfly valve 500 according to the fifth example of the present invention will be described based on FIGS. 8A and 8B.

[0117] FIG. 8A is an enlarged sectional view of a main part of a butterfly valve according to the fifth example of the present invention, and FIG. 8B is an enlarged view of part VIIIB in FIG. 8A.

[0118] Here, the butterfly valve 500 in the fifth example is a butterfly valve in which the shape of the bearing unit 140 in the butterfly valve 100 in the first example is modified, and has many components in common with the butterfly valve 100 in the first example. Thus, detailed explanation of common components will be omitted, and only 500-series signs with the same last two digits will be given.

[0119] As shown in FIG. 8A, in a bearing unit 540 in the fifth example, a support bush 542 is inserted into a sealing bush 541.

<1. Sealing Bush>

[0120] The sealing bush 541 is formed from a cylindrical base 541c and a cylindrical protrusion 541d that protrudes from the base 541c in the axial direction.

[0121] As shown in FIG. 8A, an outer peripheral surface 541d1 of the protrusion 541d is flush with an outer peripheral surface 541c1 of the base 541c.

[0122] Further, as shown in FIG. 8A, an inner diameter s1 of the protrusion 541d is larger than the inner diameter s of the base 541c.

[0123] Further, as shown in FIG. 8A, an axial length Ls1 of the protrusion 541d is longer than the axial length Ls of the base 541c.

[0124] Further, in the sealing bush 541 in the present example, metal aggregate 541a is partially exposed on the inner diameter side as shown in FIG. 8B.

[0125] Therefore, the support bush 542 inserted into the sealing bush 541 engages with the metal aggregate 541a of the sealing bush 541.

<2. Support Bush>

[0126] The support bush 542 is formed from a cylindrical base 542a and a cylindrical protrusion 542b that protrudes from the base 542a in the axial direction.

[0127] An inner peripheral surface 542b1 of the protrusion 542b is flush with an inner peripheral surface 542al of the base 542a.

[0128] That is, as shown in FIG. 8A, the inner diameter b of the protrusion 542b is equal to the inner diameter of the base 542a and is slightly smaller than the inner diameter s of the sealing bush 541.

[0129] As shown in FIG. 8A, an outer diameter bo1 of the protrusion 542b is smaller than an outer diameter bo of the base 542a.

[0130] Further, as shown in FIG. 8A, the outer diameter bo1 of the protrusion 542b is approximately equal to the inner diameter s1 of the protrusion 541d of the sealing bush 541.

[0131] As shown in FIG. 8A, an axial length Lb1 of the protrusion 542b is longer than the axial length Lb2 of the base 542a.

[0132] Further, as shown in FIG. 8A, 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.

[0133] In the present example, the protrusion 542b of the support bush 542 is located closer to a valve shaft 520 than the protrusion 541d of the sealing bush 541, but the protrusion 541d of the sealing bush 541 may be located closer to the valve shaft 520 than the protrusion 542b of the support bush 542.

[0134] The butterfly valve 500 formed in this way in the fifth example has the structure in which the support bush 542 is inserted into the sealing bush 541. Thereby, since the bearing unit 540 can be easily handled as an integral member, it is possible to efficiently assemble the butterfly valve 500.

Example 6

[0135] Next, a butterfly valve 600 according to the sixth example of the present invention will be described based on FIGS. 9A and 9B.

[0136] FIG. 9A is an exploded perspective view of a bearing unit in a butterfly valve according to the sixth example of the present invention, and FIG. 9B is an enlarged sectional view of a main part of the butterfly valve taken along the IXB-IXB cross section in FIG. 9A.

[0137] Here, the butterfly valve 600 in the sixth example is a butterfly valve in which the shape of the bearing unit 540 in the butterfly valve 500 in the fifth example is modified, and has many components in common with the butterfly valve 500 in the fifth example. Thus, detailed explanation of common components will be omitted, and only 600-series signs with the same last two digits will be given.

[0138] As shown in FIG. 9A, in a bearing unit 640 in the sixth example, protrusions 641d2 are provided to protrude from the inner peripheral surface of a protrusion 641d of a sealing bush 641.

[0139] When inserting a support bush 642 into the sealing bush 641, since the sealing bush 641 is softer than the support bush 642, as shown in FIG. 9B, 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.

[0140] In the butterfly valve 600 formed in this way in the sixth example, the protrusion 641d2 is formed on the sealing bush 641. Thereby, since the protrusion 641d2 serves as an insertion guide when inserting the support bush 642 into the sealing bush 641, it is possible to improve the assemblability of a bearing unit 640, and even if the sealing bush 641 is stuck to a flange 621 of the valve shaft 620, since the sealing bush 641 to which the valve shaft 620 is stuck slides relative to the support bush 642, it is possible to maintain the function of the butterfly valve for a long period of time.

Modified Example

[0141] Although the butterfly valves according to the examples of the present invention have been described above, the butterfly valve in the present invention is not limited to the butterfly valves of the examples described above.

[0142] For example, in the examples described above, the metal aggregate is woven with stainless steel wires, but the metal aggregate may be woven with any metal wires as long as they are metal wires. However, in order to reliably seal the space between the housing and the sealing bush, it is preferable that the metal aggregate is woven with metal wires having the linear expansion coefficient comparable to that of the material of the housing.

[0143] For example, in the examples described above, the valve plate is provided on the upstream side of the valve shaft. However, the position of the valve plate is not limited to there, and the valve plate may be provided on the downstream side of the valve shaft.

[0144] For example, in the examples described above, the support bush is made of stainless steel as the housing is. However, the material of the support bush is not limited to this material, and may be made of, for example, hard carbon or ceramics.

REFERENCE SIGNS LIST

[0145] 100, 200, 300, 400, 500, 600 butterfly valve [0146] 110 valve plate [0147] 120, 220, 320, 420, 520 valve shaft [0148] 121, 321, 421 flange [0149] 321A, 421A sealing bush contact surface [0150] 130 connecting bolt [0151] 140, 240, 340, 440, 540 bearing unit [0152] 141, 241, 341, 441, 541, 641 sealing bush [0153] 141A outer peripheral surface [0154] 141B, 341B, 441B valve shaft opposing surface [0155] 241C, 441C support bush opposing surface [0156] 141a, 541a metal aggregate [0157] 141b, 541b graphite [0158] 541c base [0159] 541c1 outer peripheral surface [0160] 541d, 641d protrusion [0161] 541d1 outer peripheral surface [0162] 641d2 protrusion [0163] 142, 242, 342, 442, 542, 642 support bush [0164] 142A outer peripheral surface [0165] 242C, 442C sealing bush opposing surface [0166] 542a base [0167] 542a1 inner peripheral surface [0168] 542b protrusion [0169] 542b1 inner peripheral surface [0170] 150 housing [0171] 151 fixed side housing [0172] 152 detachable side housing [0173] 160 pressing spring [0174] 170 valve shaft rotation mechanism [0175] 171 rotary plate [0176] 171a spring suppressing portion [0177] 171b arm portion [0178] 172 fixing nut [0179] 173 stopper [0180] EP1 shaft insertion hole [0181] EP exhaust pipe [0182] EG exhaust gas [0183] C central axis of valve shaft [0184] F diameter of flange [0185] i inner diameter of housing [0186] P diameter of shaft insertion hole of exhaust pipe [0187] s inner diameter of sealing bush (base) [0188] s1 inner diameter of protrusion of sealing bush [0189] b inner diameter of support bush (protrusion) [0190] bo outer diameter of support bush (base) [0191] bo1 outer diameter of protrusion of support bush [0192] h diameter of through hole of detachable side housing [0193] d diameter of valve shaft [0194] Ls axial length of sealing bush (base) [0195] Ls1 axial length of sealing bush (protrusion) [0196] Lb axial length of support bush [0197] Lb1 axial length of sealing bush (protrusion) [0198] Ls2 axial length of sealing bush (base)