scarf

Abstract

To suppress change of a position of sound absorption material of a muffler.SOLUTION: In a muffler, an inside flow passage in an inner pipe part is opened and closed by a valve, an outside flow passage is formed between the inner pipe part and an outer shell part, and a partitioning part forms a sound absorption chamber. An area of at least one first opening being an inlet of the outside flow passage, an area of at least one second opening at the partitioning part and an area of at least one third opening communicating with the sound absorption chamber and the inside flow passage are set as first, second and third areas, respectively. At least one of the first to third areas is substantially the same as or smaller than a cross section area of at least one communication part formed of the valve which makes an opening of the inside flow passage minimum.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a muffler. [Background technology]

[0002] The muffler in Patent Document 1 has an inner pipe and an outer pipe that form a double-pipe structure, and a cylindrical cover member that covers the outer surface of the inner pipe is disposed between the inner pipe and the outer pipe. A control valve is disposed inside the inner pipe, and sound-absorbing material is disposed in a sound-absorbing chamber between the cover member and the inner pipe. The sound-absorbing material is disposed adjacent to the outer surface of the inner pipe, and a number of holes are formed in the portion of the inner pipe adjacent to the sound-absorbing material. Exhaust gas that flows into the sound-absorbing chamber passes through the sound-absorbing material and the many holes before flowing into the inner pipe. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-161931 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the muffler of Patent Document 1, when the inner pipe is closed by the control valve, the amount of exhaust gas flowing between the inner pipe and the outer pipe increases, and accordingly the amount of exhaust gas flowing into the sound-absorbing chamber increases. This causes the sound-absorbing material to change position due to the pressure of the exhaust gas flow, which may result in a decrease in the sound-absorbing performance of the muffler.

[0005] In one aspect of the present disclosure, it is desirable to limit changes in the position of the sound absorbing material in the muffler. [Means for solving the problem]

[0006] One aspect of the present disclosure is a muffler to be mounted on a vehicle, the muffler comprising an outer shell portion, an inner pipe portion, a valve, at least one first opening, a partition portion, a sound-absorbing material, at least one second opening, and at least one third opening. The outer shell portion has an inlet and an outlet for exhaust gas. The inner pipe portion is a cylindrical portion disposed inside the outer shell portion. The valve is configured to open and close an inner flow path, which is a flow path for exhaust gas inside the inner pipe portion, by displacing a valve body. The at least one first opening forms an exhaust gas inlet to an outer flow path between the outer shell portion and the inner pipe portion, upstream of the valve in the flow direction of the exhaust gas. The partition portion divides the outer flow path to form a sound-absorbing chamber adjacent to the inner pipe portion. The sound-absorbing material is disposed in the sound-absorbing chamber. The at least one second opening is provided in the partition portion to communicate the inside and outside of the sound-absorbing chamber. The at least one third opening is a portion of the inner pipe portion that connects the sound absorbing chamber and the inner flow path, and is located downstream of the valve in the exhaust gas flow direction. The valve body is configured to form at least one communication portion that connects the upstream side and downstream side of the valve body in the inner flow path when the opening degree of the inner flow path is minimum. The area of the at least one first opening, the area of the at least one second opening, and the area of the at least one third opening are referred to as first to third areas, respectively. At least one of the first to third areas is approximately the same as or smaller than the area of a cross section perpendicular to the exhaust gas flow direction of the at least one communication portion.

[0007] With this configuration, the amount of exhaust gas that flows into the sound-absorbing chamber when the valve is at its minimum opening can be reduced, and the position of the sound-absorbing material placed in the sound-absorbing chamber can be prevented from being pushed by the exhaust gas that has flowed into the sound-absorbing chamber.

[0008] In one aspect of the present disclosure, the partition extends from the outer peripheral surface of the inner tube portion to the inner peripheral surface of the outer shell portion and partitions the outer flow path so that a sound absorbing chamber is formed downstream of the partition. According to the above configuration, it is possible to suppress the position of the sound absorbing material arranged in the sound absorbing chamber from changing due to being pushed by the exhaust gas that has flowed into the sound absorbing chamber.

[0009] In one aspect of the present disclosure, the partition portion is a cylindrical portion arranged to surround the inner tube portion, and a gap is formed between the outer peripheral surface of the partition portion and the inner peripheral surface of the outer shell portion, and a sound-absorbing chamber may be formed between the partition portion and the inner tube portion.

[0010] According to the above configuration, it is possible to suppress the position of the sound absorbing material arranged in the sound absorbing chamber from changing due to being pushed by the exhaust gas that has flowed into the sound absorbing chamber. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a perspective view of a cross section of a muffler according to a first embodiment, the cross section including an axis and extending in the vertical direction. [Figure 2] 1 is a cross-sectional view of a muffler according to a first embodiment, the cross-section including an axis and extending in the vertical direction. [Figure 3] FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2. [Figure 4] FIG. 10 is a perspective view of a cross section of a muffler according to a second embodiment, the cross section including the axis and extending in the vertical direction. [Figure 5] FIG. 6 is a cross-sectional view of a muffler according to a second embodiment, the cross-section including the axis and extending in the vertical direction. [Figure 6] FIG. 11 is a perspective view of a cross section of a muffler according to a third embodiment, the cross section including the axis and extending in the vertical direction. [Figure 7] FIG. 10 is a cross-sectional view of a muffler according to a third embodiment, the cross-section including the axis and extending in the vertical direction. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Note that the embodiments of the present disclosure are not limited to the following embodiments, and various forms may be adopted as long as they fall within the technical scope of the present disclosure.

[0013] [1. First embodiment] [(1) Overview] A muffler 1 of the first embodiment is mounted on a vehicle and provided in the flow path of exhaust gas from the engine (see FIGS. 1 to 3). The muffler 1 has a double-pipe structure extending along an axis A, and includes an outer shell portion 2, an inner pipe portion 3, a partition portion 4, a valve 5, and sound-absorbing material 6. Exhaust gas flows down inside the muffler 1 along the axis A.

[0014] [(2) Outer shell] The outer shell portion 2 is a cylindrical portion that forms the outer surface of the muffler 1 (see Figures 1 and 2). A cross section (hereinafter simply referred to as a cross section) of the outer shell portion 2 that is perpendicular to the flow direction of the exhaust gas (in other words, the axis A) is circular, and the axis A passes through the center of the cross section. Of course, the shape of the outer shell portion 2 is not limited to this and can be determined appropriately. The outer shell portion 2 includes a main body portion 20, an upstream portion 21, an inlet portion 22, a downstream portion 23, and an outlet portion 24.

[0015] The main body 20 is a cylindrical part. The upstream portion 21 is located at the end of the main body 20 on the upstream side in the flow direction of the exhaust gas (hereinafter simply referred to as the upstream side), and the diameter of the cross section decreases toward the upstream side.

[0016] The inlet portion 22 is a wall-like portion that surrounds an inlet 25 for exhaust gas into the muffler 1, and is located at the upstream end of the upstream portion . The downstream portion 23 is located at the end of the main body 20 on the downstream side in the flow direction of the exhaust gas (hereinafter simply referred to as the downstream side), and the diameter of the cross section decreases toward the downstream side.

[0017] The outlet portion 24 is a wall-like portion that surrounds an outlet 26 for exhaust gas from the muffler 1, and is located at the downstream end of the downstream portion 23. [(3) Inner tube] The inner tube portion 3 is a cylindrical portion disposed inside the outer shell portion 2, and the axis A passes through the center of the cross section of the inner tube portion 3 (see Figures 1 and 2). Of course, the shape of the inner tube portion 3 is not limited to this and can be determined appropriately.

[0018] The upstream and downstream ends of the inner pipe 3 are attached to the inlet 22 and outlet 24 of the outer shell 2, respectively, and the inner pipe 3 extends from the exhaust gas inlet 25 to the outlet 26 of the muffler 1. That is, the upstream opening of the inner pipe 3 is connected to the inlet 25, and the downstream opening is connected to the outlet 26. Therefore, exhaust gas passing through the inlet 25 of the muffler 1 flows into the inner flow passage 11 formed inside the inner pipe 3, and exhaust gas flowing down the inner flow passage 11 passes through the outlet 26 and flows out to the outside of the muffler 1. In addition, an outer flow passage 10 is formed between the outer peripheral surface of the inner pipe 3 and the inner peripheral surface of the outer shell 2. Note that a retaining member may be provided between the upstream end of the inner pipe 3 and the inlet 22 of the outer shell 2, or between the downstream end of the inner pipe 3 and the outlet 24 of the outer shell 2. The retaining member may be a wire mesh.

[0019] The inner pipe portion 3 includes an abutment surface 30 , a plurality of first openings 31 , and a plurality of third openings 32 . The abutment surface 30 is a surface that protrudes downward from the upper part of the inner circumferential surface of the inner pipe section 3 while facing the upstream side, and is provided at approximately the center of the inner pipe section 3 in the flow direction of the exhaust gas. Specifically, a protruding section 30A that protrudes upward is formed at approximately the center of the inner pipe section 3 in the flow direction of the exhaust gas. Furthermore, a depressed section 30B is formed in the inner pipe section 3 adjacent to the downstream side of the protruding section 30A. The abutment surface 30 is formed by the portion of the protruding section 30A located on the downstream side and the portion of the depressed section 30B located on the upstream side. As will be described in detail later, the abutment surface 30 restricts rotation of the valve element 50 of the valve 5 when it is in the closed position.

[0020] The multiple first openings 31 are located upstream of a valve 5 (described later) and upstream of a partition section 4 (described later), and are multiple holes that penetrate the side wall of the inner pipe section 3, connecting the inner flow path 11 and the outer flow path 10. In other words, the multiple first openings 31 form inlets for exhaust gas to the outer flow path 10. As an example, the multiple first openings 31 are provided near both ends of the inner pipe section 3 in the left-right direction. However, the positions of the multiple first openings 31 can be determined appropriately. Furthermore, hereinafter, the total area of the multiple first openings 31 will be referred to as the first area.

[0021] The multiple third openings 32 are located downstream of a valve 5 (described later) and downstream of a partition 4 (described later), and are a large number of punched holes that penetrate the side wall of the inner pipe portion 3, connecting the inner flow path 11 with a sound-absorbing chamber 12 (described later). The multiple third openings 32 are provided around the inner pipe portion 3. Hereinafter, the total area of the multiple third openings 32 will be referred to as the third area.

[0022] [(4) Partition] The partition 4 is provided in the outer flow path 10 and is a plate-like section that divides the outer flow path 10 into an upstream chamber and a downstream chamber so as to form a sound-absorbing chamber 12 adjacent to the outer peripheral surface of the inner pipe 3, and functions as a separator (see FIGS. 1 to 3). The partition 4 is circular and has a hole formed in the center that passes through the partition 4, with the inner pipe 3 being disposed so as to pass through this hole. In other words, the partition 4 extends from the outer peripheral surface of the inner pipe 3 to the inner peripheral surface of the outer shell 2, and the sound-absorbing chamber 12 is formed between the inner pipe 3 and the outer shell 2 on the downstream side of the partition 4 (in other words, on the outlet 26 side).

[0023] A fibrous sound-absorbing material 6 is disposed in the sound-absorbing chamber 12. The fibrous sound-absorbing material 6 may be, for example, glass wool or rock wool. The sound-absorbing chamber 12 may be filled with the sound-absorbing material 6, or the sound-absorbing material 6 may be disposed in the sound-absorbing chamber 12 with gaps formed between the outer shell portion 2, the inner tube portion 3, and the partition portion 4.

[0024] The partition 4 also includes a plurality of second openings 40, an inner joint 41, and an outer joint . The second openings 40 are holes that penetrate the partition 4 and connect the upstream side and downstream side of the partition 4, in other words, the inside and outside of the sound absorbing chamber 12. The second openings 40 are arranged across the entire area of the partition 4, and as an example, are arranged in a line at regular intervals in the circumferential direction. Hereinafter, the total area of the second openings 40 is referred to as the second area.

[0025] The inner joint 41 is a wall-like portion that protrudes upstream from the edge surrounding the central hole of the partition 4, and is provided to surround the hole. The inner joint 41 abuts against the outer peripheral surface of the inner pipe 3 that passes through the hole. The inner joint 41 may also protrude downstream from the edge.

[0026] The outer joint 42 is a wall-shaped portion that protrudes upstream from the outer edge of the partition 4 and is provided to surround the partition 4. The outer joint 42 abuts against the inner circumferential surface of the main body 20 in the outer shell 2. The outer joint 42 may also protrude downstream from the outer edge.

[0027] [(5) Valve] The valve 5 is provided approximately in the center of the inner pipe portion 3 in the flow direction of the exhaust gas, and is configured to open and close the inner flow path 11 (see FIGS. 1 to 3). The valve 5 is located inside the sound absorbing chamber 12, and includes a valve element 50 and a shaft portion 51.

[0028] The shaft portion 51 is a rod-shaped portion that is arranged to extend perpendicular to the flow direction of the exhaust gas and, for example, in a substantially horizontal direction. Also, for example, the shaft portion 51 is provided slightly above the axis A. Of course, the position and orientation of the shaft portion 51 are not limited to this and can be determined appropriately.

[0029] The valve element 50 is configured to open and close the inner flow path 11 by rotating around the shaft portion 51. Here, the position of the valve element 50 at which the degree to which the inner flow path 11 is opened by the valve 5 (in other words, the opening degree of the valve 5) is minimum is defined as the closed position. When the valve element 50 is in the closed position, the portion around the upper end of the valve element 50 is in contact with the contact surface 30, and the valve element 50 is inclined relative to the radial direction of the inner pipe portion 3 with the upper end of the valve element 50 positioned more downstream than the lower end. Of course, the orientation of the valve element 50 in the closed position is not limited to this, and for example, the valve element 50 in the closed position may be perpendicular to the flow direction of the exhaust gas.

[0030] When the valve disc 50 is in the closed position, it abuts against the abutment surface 30, thereby restricting rotation by a drive member (described later) and forming a plurality of communication sections 52 that communicate between the upstream side and downstream side of the valve disc 50 in the inner flow path 11. In the first embodiment, gaps between the edge of the valve disc 50 and the inner circumferential surface of the inner pipe section 3 form the plurality of communication sections 52. More specifically, gaps are formed on the lower and upper sides of the shaft section 51 at the edge of the valve disc 50 in the closed position. However, the upper gap, which is in the center of the inner flow path 11 in the left-right direction, is blocked from the downstream side by the abutment surface 30 (see FIG. 3 ).

[0031] The total sum of the areas of the cross sections perpendicular to the flow direction of the exhaust gas in each of the plurality of communication sections 52 is defined as the communication section area. If the cross-sectional areas of the communication sections 52 are not constant, the minimum value may be used as the cross-sectional area of the communication section 52, and the communication section area may be calculated using this minimum value. In the first embodiment, the minimum value of the cross-sectional areas of the communication sections 52 located below the shaft section 51 is added to the communication section area. Furthermore, the area of the portion of the outlet of the communication section 52 located above the shaft section 51 that is not blocked by the contact surface 30 is defined as the minimum value of the cross-sectional area of the communication section 52, and this area is added to the communication section area.

[0032] It should be noted that one communication portion 52 may be formed by the valve element 50 in the closed position. Even in such a case, the area of the communication portion is calculated in the same manner. On the other hand, when the valve element 50 reaches a position where it extends along the exhaust gas flow direction, the opening of the valve 5 becomes maximum.

[0033] The valve 5 is also provided with a driving member (not shown) that rotates the valve element 50. As an example, the driving member is configured as a biasing member such as a spring, and biases the valve element 50 so that it rotates toward the closed position. When the valve element 50 is in the closed position, the driving member biases the portion around the upper end of the valve element 50 so that it presses against the abutment surface 30.

[0034] In the first embodiment, as an example, both ends of the shaft 51 may protrude to the outside by passing through holes (not shown) formed in the outer shell 2. The driving member may be disposed outside the outer shell 2 and may bias the valve body 50 via the ends of the shaft 51 protruding to the outside of the outer shell 2.

[0035] Therefore, when the amount of exhaust gas flowing down the inner flow passage 11 is small and the pressure of the exhaust gas is low, the valve element 50 of the valve 5 is held in the closed position by the drive member. On the other hand, when the amount of exhaust gas flowing down the inner flow passage 11 increases and the pressure of the exhaust gas increases, the valve element 50 in the closed position rotates in the opposite direction to when moving toward the closed position, and the opening of the valve 5 increases.

[0036] Of course, the present invention is not limited to this, and the driving member may be configured as, for example, an actuator (for example, a motor) that rotates the valve element 50 toward the closed position. Similarly, when the pressure of the exhaust gas flowing down the inner flow path 11 is low, the driving member may displace the valve element 50 to the closed position to minimize the opening of the valve 5, and increase the opening of the valve 5 as the pressure of the exhaust gas increases.

[0037] [(6) Areas 1 to 3] In the first embodiment, as an example, the first area of the multiple first openings 31 and the second area of the multiple second openings 40 are approximately the same, and the third area of the multiple third openings 32 is larger than the first and second areas (see Figures 1 to 3).

[0038] The first and second areas are substantially the same as the area of the communication portion, although the first and second areas may be smaller than the area of the communication portion. Alternatively, the first and second areas may be different, and the third area may be larger than the first and second areas, and the smaller of the first and second areas may be substantially the same as or smaller than the communication portion area.

[0039] [2. Second Embodiment] The muffler 1 of the second embodiment has a similar configuration to that of the first embodiment, but differs from the first embodiment in the first to third openings 31, 40, 32 (see FIGS. 4 and 5). The following describes the differences between the muffler 1 of the second embodiment and the first embodiment.

[0040] In the second embodiment, the multiple third openings 32 are located downstream of the partition section 4 and the valve 5 in the inner pipe section 3, as in the first embodiment. Moreover, the multiple third openings 32 are provided in the upper part of the inner pipe section 3, as an example. Note that the multiple third openings 32 are not limited to being located in the upper part of the inner pipe section 3, and may be determined as appropriate. Furthermore, in the second embodiment, the number of punched holes that are the multiple third openings 32 is smaller than in the first embodiment, and the third area of the multiple third openings 32 is smaller.

[0041] The third area is smaller than the total area of each of the first and second openings 31, 40. Furthermore, the third area and the communication portion area are substantially the same. Note that the third area may be smaller than the communication portion area.

[0042] 3. Third Embodiment [(1) Overview] The muffler 1 of the third embodiment has a similar configuration to that of the first embodiment, but differs from the first embodiment in the inner pipe portion 3 and the partition portion 7 (see FIGS. 6 and 7). Below, the differences between the muffler 1 of the third embodiment and the first embodiment will be described.

[0043] [(2) Inner tube] The inner tube portion 3 of the third embodiment is a cylindrical portion disposed inside the outer shell portion 2, similar to the first embodiment, and the axis A passes through the center of the cross section of the inner tube portion 3 (see FIGS. 6 and 7).

[0044] However, in the third embodiment, the upstream end of the inner tube portion 3 is positioned away from the inlet portion 22 of the outer shell portion 2, and differs from the first embodiment in that it is located downstream of the upstream end of the main body portion 20 of the outer shell portion 2.

[0045] That is, in the third embodiment, the upstream opening 33 of the inner pipe portion 3 is provided at a position away from the inlet 25 of the muffler 1. In addition, the outer flow passage 10 formed between the outer peripheral surface of the inner pipe portion 3 and the inner peripheral surface of the outer shell portion 2 is located downstream of the opening 33 of the inner pipe portion 3 inside the outer shell portion 2.

[0046] In the third embodiment, the multiple first openings 31 are not provided in the inner pipe portion 3. The opening between the edge portion surrounding the upstream opening 33 in the inner pipe portion 3 and the inner peripheral surface of the outer shell portion 2 becomes the first opening 31.

[0047] The multiple third openings 32 and the valve 5 are provided in the inner pipe portion 3 in the same manner as in the first embodiment. More specifically, the valve 5 is arranged upstream of a partition portion 7, which will be described later, and the multiple third openings 32 are arranged inside a main body portion 70 of the partition portion 7 (in other words, the sound-absorbing chamber 12).

[0048] [(3) Partition] The partition portion 7 of the third embodiment is a cylindrical portion that is provided around the inner pipe portion 3 to form a double-pipe structure (see FIGS. 6 and 7). The outer peripheral surface of the partition portion 7 is spaced from the inner peripheral surface of the outer shell portion 2, and the axis A passes through the center of the cross section of the partition portion 7. Of course, the shape of the partition portion 7 is not limited to this and can be determined appropriately. The partition portion 7 includes a main body portion 70, an upstream portion 71, a downstream portion 72, and a plurality of second openings 73.

[0049] The main body portion 70 is a cylindrical portion and is disposed so as to be spaced apart from the inner pipe portion 3 . The upstream section 71 is located at the upstream end of the main body section 70, and the cross-sectional diameter thereof decreases toward the upstream side. The downstream section 72 is located at the downstream end of the main body section 70, and the cross-sectional diameter thereof decreases toward the downstream side.

[0050] The upstream end of the upstream section 71 and the downstream end of the downstream section 72 each have a joint, which is joined to the outer circumferential surface of the inner pipe section 3. A sound-absorbing chamber 12 is formed between the inner circumferential surface of the partition section 7 and the outer circumferential surface of the inner pipe section 3, and a sound-absorbing material 6 is arranged in the sound-absorbing chamber 12 in the same manner as in the first embodiment.

[0051] The second openings 73 are located, for example, at the top of the partition 7 and are configured as multiple punched holes that penetrate the partition 7, connecting the inside and outside of the sound absorbing chamber 12. The positions of the second openings 73 are not limited to the top of the partition 7 and can be determined as appropriate. The second openings 73 are, for example, provided to face the third openings 32 in the radial direction of the partition 7. However, this is not limiting, and the second openings 73 may be provided upstream or downstream of the third openings 32. As in the first embodiment, the total area of the second openings 73 is defined as the second area.

[0052] [(4) Regarding Areas 1 to 3] In the third embodiment, the first area of the first opening 31 and the third area of the plurality of third openings 32 are each larger than the second area of the plurality of second openings 73 (see FIGS. 6 and 7). The second area and the communication portion area are substantially the same. Note that the second area may be smaller than the communication portion area.

[0053] Alternatively, the second and third areas may be substantially the same as each other, and the second and third areas may be substantially the same as or smaller than the communicating portion area. Alternatively, the first and second areas may be larger than the third area, and the third area may be substantially the same as or smaller than the communicating portion area.

[0054] Furthermore, the first area may be reduced by providing a blocking portion that blocks a portion of the first opening 31. Then, for example, the first area may be smaller than each of the second and third areas, and further, the first area may be approximately the same as or smaller than the communication portion area.

[0055] [4. Effects] (1) According to the above embodiment, at least one of the first to third areas is substantially the same as or smaller than the communication section area. Therefore, when the valve body 50 of the valve 5 is in the closed position and the opening of the valve 5 is at a minimum, the amount of exhaust gas flowing into the sound absorbing chamber 12 can be reduced. This reduces the change in position of the sound absorbing material 6 arranged in the sound absorbing chamber 12 due to being pushed by the exhaust gas that has flowed into the sound absorbing chamber 12. In other words, it is possible to reduce the sound absorbing material 6 moving downstream of the sound absorbing chamber 12 due to being pushed by the flow of exhaust gas, thereby reducing the silencing performance of the muffler 1.

[0056] (2) Furthermore, the exhaust gas flowing down the outer flow path 10 is diffused just before the partition 4, and then passes through the multiple second openings and flows into the sound-absorbing chamber 12. This prevents the flow of exhaust gas flowing into the sound-absorbing chamber 12 from being biased toward a specific location, and prevents the sound-absorbing material 6 from being pressed by the exhaust gas.

[0057] (3) The mufflers 1 of the first and second embodiments have a configuration suitable for suppressing noise over a relatively wide frequency range, while the muffler 1 of the third embodiment has a configuration suitable for suppressing noise over a relatively low to mid-frequency range.

[0058] 6. Other Embodiments (1) In the first and second embodiments, a plurality of each of the first to third openings 31, 40, and 32 are provided. In the third embodiment, one first opening 31 is provided, and a plurality of each of the second and third openings 73 and 32 are provided. However, in the first and second embodiments, the number of each of the first to third openings 31, 40, and 32 may be one. In the third embodiment, the number of first openings 31 may be multiple, and the number of each of the second and third openings 73 and 32 may be one. Of course, even in such a case, the first to third areas are determined in the same manner.

[0059] (2) In the first to third embodiments, the communication portion 52 is formed by a plurality of gaps between the valve element 50 in the closed position and the inner circumferential surface of the inner pipe portion 3. However, this is not limiting, and instead of or in addition to such gaps, the communication portion may be formed by a hole that penetrates the valve element 50 and communicates the upstream side with the downstream side of the valve element 50. Even in such a case, the area of the communication portion is determined based on the area of the cross section perpendicular to the flow direction of the exhaust gas, similar to when the communication portion is formed by a gap between the valve element 50 and the inner pipe portion 3.

[0060] (3) Multiple functions of one component in the above embodiments may be realized by multiple components, or one function of one component may be realized by multiple components. Also, multiple functions of multiple components may be realized by one component, or one function realized by multiple components may be realized by one component. Also, part of the configuration of the above embodiments may be omitted. Also, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments. [Explanation of symbols]

[0061] 1...muffler, 10...outer flow path, 11...inner flow path, 12...sound-absorbing chamber, 2...outer shell portion, 20...main body portion, 21...upstream portion, 22...inlet portion, 23...downstream portion, 24...outlet portion, 25...inlet, 26...outlet, 3...inner pipe portion, 30...contact surface, 31...first opening, 32...third opening, 33...opening, 4...partition portion, 40...second opening, 41...inner joint portion, 42...outer joint portion, 5...valve, 50...valve body, 51...shaft portion, 52...communicating portion, 6...sound-absorbing material, 7...partition portion, 70...main body portion, 71...upstream portion, 72...downstream portion, 73...multiple second openings.

Claims

1. A muffler mounted on a vehicle, an outer shell having an inlet and an outlet for exhaust gas; an inner tube portion that is a cylindrical portion disposed inside the outer shell portion; a valve configured to open and close an inner flow path, which is a flow path of exhaust gas inside the inner pipe portion, by displacing a valve body; at least one first opening that forms an exhaust gas inlet into an outer flow passage between the outer shell portion and the inner pipe portion, the exhaust gas inlet being located upstream of the valve in the flow direction of the exhaust gas; a partition portion that partitions the outer flow path so as to form a sound absorbing chamber adjacent to the inner pipe portion; a sound-absorbing material disposed in the sound-absorbing chamber; at least one second opening provided in the partition portion so as to communicate the inside and the outside of the sound absorbing chamber; at least one third opening, which is a portion in the inner pipe portion that communicates the sound absorbing chamber with the inner flow path and is provided downstream of the valve in the flow direction of the exhaust gas, the valve element is configured to form at least one communication portion that communicates the upstream side and the downstream side of the valve element in the inner flow path when the opening degree of the inner flow path is minimum, a total area of the at least one first opening, a total area of the at least one second opening, and a total area of the at least one third opening are defined as first to third areas, respectively; At least one of the first to third areas is substantially the same as or smaller than the area of a cross section perpendicular to the flow direction of the exhaust gas in the at least one communication portion. scarf.

2. 2. The muffler of claim 1, The partition portion extends from the outer peripheral surface of the inner pipe portion to the inner peripheral surface of the outer shell portion, and partitions the outer flow path so that the sound absorbing chamber is formed on the downstream side of the partition portion. scarf.

3. 2. The muffler of claim 1, The partition portion is a cylindrical portion provided so as to surround the inner tube portion, and a gap is formed between the outer peripheral surface of the partition portion and the inner peripheral surface of the outer shell portion, and the sound absorbing chamber is formed between the partition portion and the inner tube portion. scarf.

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