Butterfly valve bearing structure

Abstract

To improve abrasion resistance.SOLUTION: A bearing structure of a butterfly valve includes: a housing having an exhaust passage; a valve body provided between an upstream and a downstream of the exhaust passage; a shaft to which the valve body is attached; a first support part which supports the first end side of the shaft in an atmosphere open state in a manner that the first end side may rotate relative to the housing; a second support part which supports the second end side of the shaft in a closing state in a manner that the second end side may rotate relative to the housing; a shielding part which shields the second end side of the shaft from the upstream side of the exhaust passage; and a communication part which allows the second end side of the shaft and the downstream side of the exhaust passage to communicate with each other.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a bearing structure for a butterfly valve. [Background technology]

[0002] Patent Document 1 discloses the following butterfly valve for an exhaust valve. The butterfly valve includes a rotating shaft provided with a valve element that opens and closes an exhaust passage; a first sleeve having a cylindrical portion rotatably supporting one side of the valve element relative to a housing and a bottom portion closing one side of the cylindrical portion; and a second sleeve having a cylindrical portion rotatably supporting the other side of the valve element relative to the housing. A space is formed between one end face of the rotating shaft and the first sleeve. The rotating shaft is formed with a gas passage that connects the exhaust passage and the space. Exhaust gas in the exhaust passage flows into the space through the gas passage and then returns to the exhaust passage through a gap between the inner diameter surface of the cylindrical portion of the first sleeve and the outer diameter surface of the rotating shaft. Therefore, wear debris generated on the sliding surface between the first sleeve and the rotating shaft is discharged into the exhaust passage together with the exhaust gas. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-71629 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if gas accumulates in the space between one end face of the rotating shaft and the first sleeve, the pressure in the space may become too high. In this case, the pressure in the space pushes one end face of the rotating shaft axially (towards the exhaust passage). This then pushes the rotating shaft to the other side, pressing the valve disc against the second sleeve. Because the valve disc rotates with the rotating shaft, there is a risk of wear at the sliding portion between the valve disc and the second sleeve. In future development, a structure with even greater wear resistance is required to meet the demands for even higher pressures and higher operating speeds.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a bearing structure for a butterfly valve that can improve wear resistance. [Means for solving the problem]

[0006] A bearing structure for a butterfly valve according to one aspect of the present invention includes a housing having an exhaust passage, a valve element provided between upstream and downstream of the exhaust passage, a shaft to which the valve element is attached, a first support portion that rotatably supports a first end side of the shaft with respect to the housing in an atmosphere-open state, a second support portion that rotatably supports a second end side of the shaft with respect to the housing in a closed state, a blocking portion that blocks the second end side of the shaft from the upstream side of the exhaust passage, and a communicating portion that communicates the second end side of the shaft with the downstream side of the exhaust passage. The second support portion includes a cylindrical bushing that rotatably supports the second end of the shaft relative to the housing, and the bushing has a communication passage that opens at one end to a second end space facing the second end of the shaft and at the other end to a downstream side of the exhaust passage. . [Effects of the Invention]

[0007] According to the above aspect, it is possible to improve the wear resistance. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of an exhaust system according to a first embodiment. [Figure 2] 1 is a diagram including a cross section of a bearing structure of a butterfly valve according to a first embodiment. [Figure 3] FIG. 3 is a cross-sectional view of a bearing structure on a second end side of the shaft according to the first embodiment. [Figure 4]FIG. 3 is a perspective view of a second bush according to the first embodiment. [Figure 5] FIG. 3 is a perspective view of a housing-side passage according to the first embodiment. [Figure 6] FIG. 10 is a cross-sectional view of a bearing structure on a second end side of a shaft according to a second embodiment. [Figure 7] FIG. 10 is a perspective view of a second bush according to a second embodiment. [Figure 8] FIG. 11 is a cross-sectional view of a bearing structure on a second end side of a shaft according to a third embodiment. [Figure 9] FIG. 11 is a perspective view of a second end side of a shaft according to a third embodiment. [Figure 10] FIG. 11 is a perspective view of a second bush according to a third embodiment. [Figure 11] FIG. 10 is a cross-sectional view of a bearing structure on the second end side of a shaft according to a fourth embodiment. [Figure 12] FIG. 10 is a perspective view of a second end side of a shaft according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the embodiment, an example of a bearing structure for a butterfly valve will be described, in which the bearing structure is applied to an exhaust system of an engine.

[0010] First Embodiment <Exhaust system> FIG. 1 is a diagram showing an example of an exhaust system 1 according to the first embodiment. As shown in Fig. 1, the exhaust system 1 includes an engine 2, a high-pressure stage turbo 3, a low-pressure stage turbo 4, an aftertreatment device 5, an exhaust throttle valve 6, and a bypass valve 7. The components of the exhaust system 1 are connected to related elements via piping. In Fig. 1, the arrows indicate the direction of gas flow through the piping.

[0011] The engine 2 is an example of an internal combustion engine, for example, a multi-cylinder diesel engine. The high-pressure stage turbo 3 and the low-pressure stage turbo 4 are turbochargers that compress the intake air of the engine 2 by using the exhaust air of the engine 2. The high-pressure stage turbo 3 and the low-pressure stage turbo 4 constitute a two-stage turbo 8. The intake air passes through the low-pressure stage turbo 4 and then the high-pressure stage turbo 3 before being led to the combustion chamber of the engine 2. A portion of the exhaust air of the engine 2 passes through the high-pressure stage turbo 3 and is led to the low-pressure stage turbo 4. Another portion of the exhaust air of the engine 2 does not pass through the high-pressure stage turbo 3, but passes through a bypass valve 7 and is led to the low-pressure stage turbo 4.

[0012] The aftertreatment device 5 is a device that purifies particulate matter (PM) contained in the exhaust gas of the engine 2. For example, the aftertreatment device 5 includes a DOC (Diesel Oxidation Catalyst) provided in the exhaust pipe and a DPF (Diesel Particulate Filter) that is a filter that collects PM in the exhaust gas of the engine 2. For example, the aftertreatment device 5 oxidizes soot collected downstream of the DPF with nitrogen dioxide converted by the DOC provided upstream of the DPF to carbon dioxide, thereby removing the soot.

[0013] For example, in the exhaust system 1, a regeneration operation (DPF regeneration operation) is periodically performed to burn PM accumulated in the DPF. During this regeneration operation, the exhaust gas temperature and the DOC temperature are forcibly increased. For example, the regeneration operation is performed by post-injection to mix a small amount of fuel into the exhaust gas in the engine 2.

[0014] The regeneration operation may be performed by injecting fuel (HC) into the exhaust pipe upstream of the DOC (hereinafter also referred to as HC dosing), thereby burning the HC inside the DOC provided upstream of the DPF and raising the temperature of the DPF. The regeneration operation may also be performed by combining post-injection and HC dosing.

[0015] The exhaust throttle valve 6 is provided downstream of the low-pressure stage turbo 4. The exhaust throttle valve 6 is provided between the low-pressure stage turbo 4 and the after-treatment device 5. The exhaust throttle valve 6 is provided in an exhaust pipe connecting the low-pressure stage turbo 4 and the after-treatment device 5. The exhaust throttle valve 6 normally fully opens the exhaust passage. The exhaust throttle valve 6 has the role of regulating the exhaust temperature. For example, during after-treatment regeneration, the exhaust throttle valve 6 narrows the exhaust passage according to the load, thereby increasing the exhaust temperature. The butterfly valve bearing structure 10 of the embodiment is provided in the exhaust throttle valve 6.

[0016] The bypass valve 7 is provided between the two-stage turbo 8. The bypass valve 7 is provided at a portion branching from the exhaust pipe connecting the engine 2 and the high-pressure stage turbo 3 and connecting to the low-pressure stage turbo 4. The bypass valve 7 is provided upstream of the low-pressure stage turbo 4. The bypass valve 7 is a valve for preventing the turbo from over-revving. The bypass valve 7 opens and closes a bypass circuit (exhaust passage) from the inlet to the outlet of the high-pressure stage turbo 3 to prevent the in-cylinder pressure from exceeding or exceeding the allowable turbo speed. For example, the bypass valve 7 is set so that a target inlet manifold pressure (IMP) is not reached even when fully closed. For example, the bypass valve 7 is controlled to close (e.g., fully closed) when the actual IMP is lower than the target IMP, and to open (e.g., fully open) when the actual IMP is higher than the target IMP. The butterfly valve bearing structure 10 of the embodiment is also provided in the bypass valve 7.

[0017] <Butterfly valve bearing structure> Next, a description will be given of the butterfly valve bearing structure 10 provided in each of the exhaust throttle valve 6 and the bypass valve 7 of the embodiment. Fig. 2 is a diagram including a cross section of the butterfly valve bearing structure 10 according to the first embodiment. Fig. 2 corresponds to a vertical cross section showing the butterfly valve in an open state. As shown in FIG. 2, the bearing structure 10 of the butterfly valve includes a housing 11, a valve body 12, a shaft 13, a first support portion 14, a second support portion 15, a blocking portion 16, and a communicating portion 17.

[0018] In the following description, the left-right direction on the paper surface of FIG. 2 is the exhaust direction along the exhaust passage 20, with the left side being the upstream side (engine side) and the right side being the downstream side (exhaust port side). Furthermore, the up-down direction on the paper surface of FIG. 2 is the axial direction of the shaft 13, with the upper side being the first end side of the shaft 13 and the lower side being the second end side of the shaft 13. For example, the shaft 13 is disposed horizontally with respect to the ground. Alternatively, the shaft 13 may be disposed vertically with respect to the ground. Alternatively, the shaft 13 may be disposed at an angle with respect to the ground. For example, the arrangement of the shaft 13 can be changed according to required specifications.

[0019] The housing 11 has an exhaust passage 20. The housing 11 has a cylindrical shape that is aligned with the exhaust direction. The housing 11 has bearing holes 21, 22 that are perpendicular to the exhaust passage 20. The bearing holes 21, 22 are provided on the first end side and the second end side of the shaft 13. Hereinafter, the bearing hole on the first end side of the shaft 13 will also be referred to as the "first bearing hole 21," and the bearing hole on the second end side of the shaft 13 will also be referred to as the "second bearing hole 22."

[0020] The valve element 12 is provided between the upstream and downstream of the exhaust passage 20. For example, the valve element 12 is an elliptical member. The minor axis of the valve element 12 is smaller than the inner diameter of the exhaust passage 20. The major axis of the valve element 12 is larger than the inner diameter of the exhaust passage 20. The valve element 12 may also be a disk-shaped member. In this case, the diameter of the valve element 12 is smaller than the inner diameter of the exhaust passage 20. For example, the shape of the valve element 12 can be changed according to required specifications.

[0021] The valve element 12 is attached to the shaft 13. For example, the valve element 12 is fixed to the shaft 13 by a fastening member such as a bolt. The shaft 13 is a cylindrical member. The axial length of the shaft 13 is greater than the inner diameter of the exhaust passage 20.

[0022] <1st support part> The first support part 14 rotatably supports the first end side of the shaft 13 relative to the housing 11 in an atmosphere-open state. The first end side of the shaft 13 corresponds to the upper side of the shaft 13 in the plane of the paper in FIG. 2 relative to the valve body 12. The first support part 14 includes a cylindrical bushing 30 (hereinafter also referred to as the "first bushing 30") that rotatably supports the first end side of the shaft 13 relative to the housing 11, and an annular collar 31 adjacent to the first bushing 30.

[0023] For example, the first bushing 30 is press-fitted into the first bearing hole 21 of the housing 11. The first end side of the shaft 13 is provided so as to be slidable relative to the inner peripheral surface of the first bushing 30. A seal ring 32 (hereinafter also referred to as the "first seal ring 32") is provided between the first end side of the shaft 13 and the first bushing 30.

[0024] The first seal ring 32 is provided at the sliding portion between the first end side of the shaft 13 and the first bush 30. The first seal ring 32 separates the first end side space (external space) facing the first end of the shaft 13 from the exhaust passage 20. The first seal ring 32 prevents exhaust gas from escaping into the external space through the gap between the shaft 13 and the first bush 30. The first seal ring 32 reduces gas leakage at all times, not just when the valve is fully closed. The first end of the shaft 13 is located above the collar 31. The first end of the shaft 13 is exposed to the external space of the housing 11.

[0025] A first end of the shaft 13 is connected to a lever 35 that constitutes a link mechanism. The shaft 13 rotates integrally with the lever 35, which rotates when driven by an actuator 36. The rotation of the shaft 13 opens and closes the valve body 12, thereby changing the area of ​​the exhaust passage 20 (the passage area inside the housing 11 as viewed from the exhaust direction). A spring 37 is provided between the lever 35 and the housing 11.

[0026] The spring 37 has a spiral shape that follows the shaft 13. For example, the lever 35 has a notch onto which one end of the spring 37 hooks. For example, the housing 11 has a protrusion onto which the other end of the spring 37 hooks. The spring 37 biases the lever 35 toward the fully open side (the side toward which the valve body 12 opens). When the actuator 36 is driven, the lever 35 rotates against the biasing force of the spring 37, and the valve body 12 moves toward the closing side.

[0027] <Second support part> The second support part 15 rotatably supports the second end side of the shaft 13 relative to the housing 11 in a closed state. The second end side of the shaft 13 corresponds to the lower side of the shaft 13 in the plane of the paper in FIG. 2 than the valve body 12. The second support part 15 includes a cylindrical bushing 40 (hereinafter also referred to as "second bushing 40") that rotatably supports the second end side of the shaft 13 relative to the housing 11.

[0028] For example, the second bushing 40 is press-fitted into the second bearing hole 22 of the housing 11. The second end side of the shaft 13 is provided so as to be slidable relative to the inner circumferential surface of the second bushing 40. A seal ring 42 (hereinafter also referred to as the "second seal ring 42") is provided between the second end side of the shaft 13 and the second bushing 40.

[0029] FIG. 3 is a cross-sectional view of the bearing structure on the second end side of the shaft 13 according to the first embodiment. 3, the second seal ring 42 is provided at the sliding portion between the second end side of the shaft 13 and the second bushing 40. The second seal ring 42 separates a second end side space 43 facing the second end of the shaft 13 from the exhaust passage 20.

[0030] The second bearing hole 22 of the housing 11 has an inner hole 25 that communicates with the exhaust passage 20 and an outer hole 26 that communicates with the inner hole 25. The inner hole 25 is disposed axially inward of the outer hole 26 on the shaft 13. The diameter of the outer hole 26 is larger than the diameter of the inner hole 25.

[0031] The second bushing 40 includes a cylindrical bushing body 45 that fits within the inner hole 25, and an annular flange 46 that fits within the outer hole 26. For example, the bushing body 45 is press-fit into the inner hole 25. For example, the flange 46 is fitted into the outer hole 26 with a gap between them. For example, the bushing body 45 and the flange 46 are integrally formed from the same member.

[0032] A plug 50 that closes the second end side of the shaft 13 is attached to the housing 11. For example, the plug 50 is press-fitted into the outer hole 26. The outer hole 26 is sealed by the plug 50. The plug 50 includes a cylindrical plug tubular portion 51 that fits along the outer hole 26, and a disk-shaped plug bottom portion 52. For example, the plug tubular portion 51 and the plug bottom portion 52 are integrally formed from the same member.

[0033] The second bushing 40 has a communication passage 60 (hereinafter also referred to as the "bush-side passage 60"), one end of which opens into a second end space 43 facing the second end of the shaft 13, and the other end of which opens downstream of the exhaust passage 20. The second end space 43 is formed between the second end of the shaft 13 and the plug 50.

[0034] As shown in Fig. 4, the bushing-side passage 60 is a circular hole. As shown in Fig. 3, the bushing-side passage 60 intersects the axial direction of the shaft 13 at an angle. The bushing-side passage 60 extends linearly and inclined from a portion facing the second end-side space 43 toward the axial inside of the second bushing 40 so as to be positioned radially outward. One end of the bushing-side passage 60 is formed at a portion facing the second end-side space 43 on the radial inside of the bushing main body 45. The other end of the bushing-side passage 60 is formed at a portion on the outer peripheral surface of the inner hole 25 of the bushing main body 45 facing the downstream side of the exhaust passage 20.

[0035] The housing 11 has a communication passage 61 (hereinafter also referred to as the "housing-side passage 61") that communicates with the bushing-side passage 60. The housing-side passage 61 is formed in a portion of the peripheral wall of the inner hole 25 of the housing 11 that faces the downstream side of the exhaust passage 20. As shown in FIG. 5, the housing-side passage 61 is a semicircular groove. As shown in FIG. 3, the housing-side passage 61 extends linearly in parallel to the axial direction of the shaft 13. One end of the housing-side passage 61 is formed in a portion that faces the flange portion 46. The other end of the housing-side passage 61 is formed in a portion that faces the downstream side of the exhaust passage 20.

[0036] As described above, the bushing-side passage 60 has one end opening into the second end space 43 facing the second end of the shaft 13. The housing-side passage 61 has the other end opening on the downstream side of the exhaust passage 20. The bushing-side passage 60 and the housing-side passage 61 communicate with each other at the inner hole 25. Therefore, the bushing-side passage 60 and the housing-side passage 61 function as a communication section 17 that communicates between the second end side of the shaft 13 and the downstream side of the exhaust passage 20. In other words, the passages 60, 61 (holes, grooves) formed in the second bushing 40 and the housing 11 between the second end space 43 and the downstream side of the exhaust passage 20 constitute the communication section 17.

[0037] On the other hand, no hole or groove is formed in the second bushing 40 and the housing 11 between the second end space 43 and the upstream side of the exhaust passage 20. Therefore, the portion of the second bushing 40 and the housing 11 between the second end space 43 and the upstream side of the exhaust passage 20, together with the second seal ring 42, functions as a blocking section 16 that blocks the second end side of the shaft 13 from the upstream side of the exhaust passage 20. In other words, the second bushing 40 and the housing 11 do not have a passage that connects the second end space 43 and the upstream side of the exhaust passage 20.

[0038] <Action and effect> As described above, the bearing structure 10 of the butterfly valve of this embodiment comprises a housing 11 having an exhaust passage 20, a valve element 12 provided between the upstream and downstream sides of the exhaust passage 20, a shaft 13 to which the valve element 12 is attached, a first support part 14 that rotatably supports a first end side of the shaft 13 relative to the housing 11 in an atmospherically open state, a second support part 15 that rotatably supports a second end side of the shaft 13 relative to the housing 11 in a closed state, a blocking part 16 that blocks the second end side of the shaft 13 from the upstream side of the exhaust passage 20, and a communicating part 17 that communicates the second end side of the shaft 13 with the downstream side of the exhaust passage 20. According to this configuration, the communication portion 17 allows gas on the second end side of the shaft 13 to be released to the downstream side of the exhaust passage 20. This makes it possible to suppress an increase in pressure on the second end side of the shaft 13. This makes it possible to suppress the second end of the shaft 13 from being pushed axially (toward the exhaust passage 20) and causing the valve element 12 to be pressed against the first support portion 14. This makes it possible to reduce the pressure acting on the sliding portion between the valve element 12 and the first support portion 14, even when the valve element 12 rotates integrally with the shaft 13. In other words, the thrust force of the shaft 13 toward the upper side (the side open to the atmosphere) is reduced, and the force acting on the sliding portion between the valve element 12 and the first support portion 14 is reduced, thereby reducing wear. This makes it possible to improve wear resistance.

[0039] In this embodiment, the second support portion 15 includes a cylindrical second bushing 40 that rotatably supports the second end of the shaft 13 relative to the housing 11. The second bushing 40 has one end that opens into a second end space 43 facing the second end of the shaft 13, and a communication passage 60 that opens at the other end downstream of the exhaust passage 20. According to this configuration, the communication passage 60 of the second bushing 40 allows gas in the second end space 43 to be released to the downstream side of the exhaust passage 20, thereby suppressing a rise in pressure in the second end space 43. Therefore, compared to when a communication passage is provided in the shaft 13, a simpler structure can be achieved.

[0040] In this embodiment, the bearing structure 10 of the butterfly valve includes a second seal ring 42 provided between the second end side of the shaft 13 and the second support portion 15. According to this configuration, the second seal ring 42 can separate the second end space 43 from the exhaust passage 20. That is, the second seal ring 42 functions as a blocking portion 16 that separates the second end space 43 from the upstream side of the exhaust passage 20. This can suppress a rise in pressure in the second end space 43 caused by gas on the upstream side of the exhaust passage 20 entering the second end space 43. This further reduces the thrust force of the shaft 13 toward the upper side (the side open to the atmosphere), further reducing the force applied to the sliding portion between the valve body 12 and the second bushing 40, thereby further reducing wear. This can further improve wear resistance.

[0041] In this embodiment, the butterfly valve bearing structure 10 is provided on the exhaust throttle valve 6. With this configuration, the pressure downstream of the exhaust passage 20 in the exhaust throttle valve 6 becomes approximately atmospheric pressure (for example, approximately 0 to 30 kPa). Therefore, the pressure in the second end space 43 that communicates with the downstream side of the exhaust passage 20 also becomes approximately atmospheric pressure. This further reduces the thrust force that moves the shaft 13 upward (toward the atmosphere), further reducing the force applied to the sliding portion between the valve body 12 and the second bushing 40, thereby further reducing wear. Therefore, wear resistance can be further improved.

[0042] In this embodiment, the butterfly valve bearing structure 10 is provided in a bypass valve 7 for preventing over-speed of a turbo. According to this configuration, the wear resistance of the bypass valve 7 can also be improved.

[0043] In this embodiment, the butterfly valve bearing structure 10 is provided between the two-stage turbo 8. According to this configuration, the wear resistance of the configuration including the two-stage turbo 8 can be improved.

[0044] Second Embodiment In the first embodiment, an example (see FIG. 3) was described in which the passages 60, 61 (holes, grooves) formed in the second bushing 40 and the housing 11 between the second end space 43 and the downstream side of the exhaust passage 20 constitute the communicating portion 17. In the second embodiment, as shown in FIG. 6, the second embodiment differs from the first embodiment in that the passage 260 (hole) formed in the second bushing 40 between the second end space 43 and the downstream side of the exhaust passage 20 constitutes the communicating portion 17. That is, in the second embodiment, no passage that constitutes the communicating portion 17 is formed in the housing 11. In the following description, the same components as in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0045] Fig. 6 is a cross-sectional view of a bearing structure on the second end side of a shaft according to the second embodiment, and Fig. 7 is a perspective view of a second bush according to the second embodiment. 6, the second bushing 40 has a communication passage 260 that has one end opening into the second end space 43 facing the second end of the shaft 13 and the other end opening downstream of the exhaust passage 20. The communication passage 260 is formed in an L-shape. The communication passage 260 includes an axial passage 261 that opens into the second end space 43 and a radial passage 262 that opens downstream of the exhaust passage 20. The axial passage 261 and the radial passage 262 communicate with each other inside the second bushing 40.

[0046] As shown in Fig. 7, the axial passage 261 is a circular hole extending along the axial direction of the bushing main body 45 of the second bushing 40. As shown in Fig. 6, the axial passage 261 extends parallel to the axial direction of the shaft 13. One end of the axial passage 261 is formed in a portion of the bushing main body 45 facing the second end space 43. The other end of the axial passage 261 is formed in a portion of the bushing main body 45 between the second seal ring 42 and the valve body 12 (a portion closer to the exhaust passage 20 than the second seal ring 42 in the axial direction). Note that there is no axial passage 261 between the second bushing 40 and the shaft 13, and therefore the second seal ring 42 may be positioned anywhere as long as it provides a seal.

[0047] As shown in Fig. 7, the radial passage 262 is a circular hole extending in the radial direction of the bushing main body 45 of the second bushing 40. As shown in Fig. 6, the radial passage 262 extends in a direction perpendicular to (intersecting with) the axial direction of the shaft 13. One end of the radial passage 262 is connected to the other end of the axial passage 261. The other end of the radial passage 262 is formed in a portion of the outer circumferential surface of the bushing main body 45 that faces the downstream side of the exhaust passage 20.

[0048] As described above, one end of the axial passage 261 opens into the second end space 43 facing the second end of the shaft 13. The other end of the radial passage 262 opens onto the downstream side of the exhaust passage 20. The axial passage 261 and the radial passage 262 communicate with each other inside the second bushing 40. Therefore, the axial passage 261 and the radial passage 262 function as the communication part 17 that communicates between the second end side of the shaft 13 and the downstream side of the exhaust passage 20. In other words, the passages 261, 262 (holes) formed in the second bushing 40 between the second end space 43 and the downstream side of the exhaust passage 20 constitute the communication part 17.

[0049] <Action and effect> In the second embodiment, the second bushing 40 has a communication passage 260 whose one end opens into a second end space 43 facing the second end of the shaft 13 and whose other end opens downstream of the exhaust passage 20. According to this configuration, the communication passage 260 of the second bushing 40 allows gas in the second end space 43 to be released to the downstream side of the exhaust passage 20, thereby suppressing a rise in pressure in the second end space 43. Therefore, compared to when a communication passage is provided in the shaft 13, a simpler structure can be achieved.

[0050] In the second embodiment, the housing 11 does not have a passage that constitutes the communication portion 17. This configuration allows for a simpler structure than when a communication passage is provided in the housing 11.

[0051] <Third embodiment> In the first embodiment, an example was described in which the shaft 13 does not have a passage that constitutes the communication portion 17 (see FIG. 3). In the third embodiment, as shown in FIG. 8, the shaft 13 is different from the first embodiment in that a passage 360 ​​that constitutes the communication portion 17 is formed in the shaft 13. In the third embodiment, the communication portion 17 is constituted by passages 360, 364 that are formed in the shaft 13 and the second bush 40 between the second end space 43 and the downstream side of the exhaust passage 20. In the following description, the same components as in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0052] Fig. 8 is a cross-sectional view of a bearing structure on the second end side of a shaft according to the third embodiment, Fig. 9 is a perspective view of the second end side of a shaft according to the third embodiment, and Fig. 10 is a perspective view of a second bush according to the third embodiment. 8 , the shaft 13 has a shaft-side passage 360 ​​that has one end opening at the second end of the shaft 13 and the other end opening on the inner circumferential side of the second bushing 40. The shaft-side passage 360 ​​includes a shaft-side first passage 361 that opens at the second end of the shaft 13, a shaft-side second passage 362 that opens on the inner circumferential side of the second bushing 40, and a shaft-side third passage 363 that connects the shaft-side first passage 361 and the shaft-side second passage 362. The shaft-side first passage 361 and the shaft-side third passage 363 connect to each other inside the shaft 13.

[0053] As shown in Fig. 9, the shaft-side first passage 361 is a circular hole extending along the axial direction of the shaft 13. As shown in Fig. 8, the shaft-side first passage 361 extends along the central axis of the shaft 13. One end of the shaft-side first passage 361 is formed in the radial center of the second end of the shaft 13. The other end of the shaft-side first passage 361 is formed in a portion of the shaft 13 between the second seal ring 42 and the inner hole 25 (a portion closer to the second end space 43 in the axial direction than the second seal ring 42). In Fig. 9, reference numeral 41 denotes an annular groove into which the second seal ring 42 fits.

[0054] 9, the shaft-side second passage 362 is a recessed groove extending circumferentially on the outer peripheral surface of the shaft 13. The shaft-side second passage 362 is formed in a continuous ring shape over the entire circumferential direction of the outer peripheral surface of the shaft 13. As shown in FIG. 8, the shaft-side second passage 362 is formed in a portion of the outer peripheral surface of the shaft 13 between the second seal ring 42 and the inner hole 25 (at the same position in the axial direction as the other end of the shaft-side first passage 361).

[0055] 9, the shaft-side third passage 363 is a circular hole extending along the radial direction of the shaft 13. One end of the shaft-side third passage 363 is connected to the other end of the shaft-side first passage 361. The other end of the shaft-side third passage 363 is connected to a part of the shaft-side second passage 362. The shaft-side third passage 363 is formed at the same position as the shaft-side second passage 362 in the axial direction.

[0056] As shown in Fig. 8, the second bushing 40 has a bushing-side passage 364, one end of which opens to the shaft-side passage 360 ​​and the other end of which opens downstream of the exhaust passage 20. As shown in Fig. 10, the bushing-side passage 364 is a circular hole extending radially of the bushing main body 45 of the second bushing 40. As shown in Fig. 8, the bushing-side passage 364 extends in a direction perpendicular to (intersecting with) the axial direction of the shaft 13. One end of the bushing-side passage 364 is formed in a portion facing the shaft-side second passage 362. The other end of the bushing-side passage 364 is formed in a portion of the outer circumferential surface of the bushing main body 45 facing downstream of the exhaust passage 20.

[0057] As described above, the shaft-side passage 360 ​​has one end opening into the second-end space 43 facing the second end of the shaft 13. The bushing-side passage 364 has the other end opening downstream of the exhaust passage 20. The shaft-side passage 360 ​​and the bushing-side passage 364 communicate with each other within the shaft-side second passage 362. The shaft-side second passage 362 is formed around the entire outer circumferential surface of the shaft 13, in a region between the second seal ring 42 and the inner hole 25. Even when the shaft 13 is rotating, the shaft-side passage 360 ​​and the bushing-side passage 364 communicate with each other within the shaft-side second passage 362. Therefore, the shaft-side passage 360 ​​and the bushing-side passage 364 function as the communication portion 17 that communicates between the second end side of the shaft 13 and the downstream side of the exhaust passage 20. In other words, the passages 360 and 364 formed in the shaft 13 and the second bush 40 between the second end space 43 and the downstream side of the exhaust passage 20 constitute the communication portion 17.

[0058] <Action and effect> In the third embodiment, the shaft 13 has a shaft-side passage 360 ​​that opens at one end to the second end of the shaft 13 and at the other end on the inner circumferential side of the second bushing 40. The second bushing 40 has a bushing-side passage 364 that opens at one end to the shaft-side passage 360 ​​and at the other end on the downstream side of the exhaust passage 20. According to this configuration, the shaft side passage 360 ​​and the bush side passage 364 allow gas in the second end space 43 to be vented to the downstream side of the exhaust passage 20, thereby suppressing a rise in pressure in the second end space 43.

[0059] In the third embodiment, the housing 11 does not have a passage that constitutes the communication portion 17. This configuration allows for a simpler structure than when a communication passage is provided in the housing 11.

[0060] <Fourth embodiment> In the third embodiment, an example was described in which the shaft-side passage 360 ​​includes a shaft-side third passage 363 that communicates between the shaft-side first passage 361 and the shaft-side second passage 362 (see FIG. 8). In the fourth embodiment, as shown in FIG. 11, the shaft-side passage 360 ​​differs from the third embodiment in that it does not include the shaft-side third passage 363. In the fourth embodiment, passages 460, 364 formed in the shaft 13 and the second bushing 40 between the second end space 43 and the downstream side of the exhaust passage 20 constitute the communication portion 17. In the following description, the same components as those in the third embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0061] Fig. 11 is a cross-sectional view of the bearing structure on the second end side of the shaft according to the fourth embodiment, and Fig. 12 is a perspective view of the second end side of the shaft according to the fourth embodiment. 11 , the shaft 13 has a shaft-side passage 460 that has one end opening at the second end of the shaft 13 and the other end opening on the inner circumferential side of the second bushing 40. The shaft-side passage 460 includes a shaft-side first passage 461 that opens at the second end of the shaft 13, and a shaft-side second passage 462 that opens on the inner circumferential side of the second bushing 40. The shaft-side first passage 461 and the shaft-side second passage 462 communicate with each other on the outer circumferential surface of the shaft 13.

[0062] 12, the shaft-side first passage 461 is a recessed groove extending axially on the outer peripheral surface of the shaft 13. As shown in FIG. 11, one end of the shaft-side first passage 461 is formed at the radially outer end of the second end of the shaft 13. The other end of the shaft-side first passage 461 is formed in a portion of the shaft 13 between the second seal ring 42 and the inner hole 25 (a portion closer to the second end space 43 in the axial direction than the second seal ring 42). The other end of the shaft-side first passage 461 is connected to a portion of the shaft-side second passage 462.

[0063] As described above, the shaft-side passage 460 has one end opening into the second-end space 43 facing the second end of the shaft 13. The bushing-side passage 364 has the other end opening downstream of the exhaust passage 20. The shaft-side passage 460 and the bushing-side passage 364 communicate with each other within the shaft-side second passage 462. The shaft-side second passage 462 is formed around the entire outer circumferential surface of the shaft 13, in a region between the second seal ring 42 and the inner hole 25. Even when the shaft 13 is rotating, the shaft-side passage 460 and the bushing-side passage 364 communicate with each other within the shaft-side second passage 462. Therefore, the shaft-side passage 460 and the bushing-side passage 364 function as the communication section 17 that communicates between the second end of the shaft 13 and the downstream side of the exhaust passage 20. In other words, the passages 460 and 364 formed in the shaft 13 and the second bush 40 between the second end space 43 and the downstream side of the exhaust passage 20 constitute the communication portion 17.

[0064] <Action and effect> In the fourth embodiment, the shaft 13 has a shaft-side passage 460 that opens at one end to the second end of the shaft 13 and at the other end on the inner circumferential side of the second bushing 40. The second bushing 40 has a bushing-side passage 364 that opens at one end to the shaft-side passage 360 ​​and at the other end on the downstream side of the exhaust passage 20. According to this configuration, the shaft side passage 460 and the bush side passage 364 allow gas in the second end space 43 to be vented to the downstream side of the exhaust passage 20, thereby suppressing a rise in pressure in the second end space 43.

[0065] In the fourth embodiment, the shaft side passage 460 does not include the shaft side third passage 363. This configuration allows for a simpler structure than when the shaft-side third passage 363 is provided (see FIG. 9).

[0066] <Other embodiments> In the above-described embodiment, the bearing structure of the butterfly valve is described as including a second seal ring provided between the second end of the shaft and the second support portion, but this is not limiting. For example, the bearing structure of the butterfly valve does not have to include a second seal ring. For example, the configuration of the bearing structure of the butterfly valve can be changed according to required specifications.

[0067] In the above-described embodiment, the butterfly valve bearing structure is provided in an exhaust throttle valve, but this is not limiting. For example, the butterfly valve bearing structure does not have to be provided in an exhaust throttle valve. For example, the butterfly valve bearing structure may be provided in a bypass valve. For example, the installation mode of the butterfly valve bearing structure can be changed according to required specifications.

[0068] In the above-described embodiment, the butterfly valve bearing structure is provided in a bypass valve for preventing turbo overspeed, but the present invention is not limited to this. For example, the butterfly valve bearing structure does not have to be provided in a bypass valve. For example, the butterfly valve bearing structure may be provided in an exhaust throttle valve. For example, the installation mode of the butterfly valve bearing structure can be changed according to required specifications.

[0069] In the above-described embodiment, an example has been described in which the bearing structure of the butterfly valve is provided between two-stage turbos, but this is not limiting. For example, the bearing structure of the butterfly valve does not have to be provided between two-stage turbos. For example, the exhaust system does not have to include a two-stage turbo. For example, the exhaust system may include one turbo (single-stage turbo). For example, the configuration of the exhaust system can be changed according to required specifications.

[0070] Although the embodiments of the present invention have been described above, the present invention is not limited to these, and additions, omissions, substitutions, and other modifications to the configuration are possible within the scope of the spirit of the present invention, and the above-described embodiments can also be combined as appropriate. [Explanation of symbols]

[0071] 6...exhaust throttle valve, 7...bypass valve, 8...two-stage turbo, 10...bearing structure of butterfly valve, 11...housing, 12...valve body, 13...shaft, 14...first support portion, 15...second support portion, 16...blocking portion, 17...communicating portion, 20...exhaust passage, 40...second bushing (bush), 42...second seal ring (seal ring), 43...second end side space, 60...bush side passage (communicating passage), 61...housing side passage (communicating passage), 260...communicating passage, 360...shaft side passage, 364...bush side passage, 460...shaft side passage

Claims

1. a housing having an exhaust passage; a valve body provided between the upstream and downstream sides of the exhaust passage; a shaft to which the valve body is attached; a first support portion that rotatably supports a first end side of the shaft relative to the housing in an atmosphere-open state; a second support portion that rotatably supports a second end side of the shaft relative to the housing in a closed state; a blocking portion that blocks a second end side of the shaft from an upstream side of the exhaust passage; a communication portion that communicates the second end side of the shaft with the downstream side of the exhaust passage, the second support portion includes a cylindrical bushing that rotatably supports a second end side of the shaft relative to the housing, The bushing has a communication passage whose one end opens into a second end space facing the second end of the shaft and whose other end opens downstream of the exhaust passage. Butterfly valve bearing structure.

2. a housing having an exhaust passage; a valve body provided between the upstream and downstream sides of the exhaust passage; a shaft to which the valve body is attached; a first support portion that rotatably supports a first end side of the shaft relative to the housing in an atmosphere-open state; a second support portion that rotatably supports a second end side of the shaft relative to the housing in a closed state; a blocking portion that blocks a second end side of the shaft from an upstream side of the exhaust passage; a communication portion that communicates the second end side of the shaft with the downstream side of the exhaust passage, the second support portion includes a cylindrical bushing that rotatably supports a second end side of the shaft relative to the housing, the shaft has a shaft-side passage having one end that opens at the second end of the shaft and the other end that opens on the inner peripheral side of the bushing, The bushing has a bushing-side passage that opens at one end to the shaft-side passage and at the other end downstream of the exhaust passage. Butterfly valve bearing structure.

3. The shaft further includes a seal ring provided between the second end and the second support portion.

3. The bearing structure for a butterfly valve according to claim 1 or 2.

4. The butterfly valve bearing structure is provided on the exhaust throttle valve. The bearing structure for a butterfly valve according to any one of claims 1 to 3.

5. The butterfly valve bearing structure is provided in a bypass valve for preventing over-rotation of a turbo. The bearing structure for a butterfly valve according to any one of claims 1 to 3.

6. The butterfly valve bearing structure is provided between the two-stage turbo.

6. The bearing structure for a butterfly valve according to claim 5.

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