Exhaust component

Abstract

An exhaust component (100, 100a to 100i) forming an exhaust flow path that introduces an exhaust gas from an internal combustion engine includes an exhaust manifold (2, 2a to 2d) including a flange (1, 1a, 1b) including; a through-hole (11 to 14) formed thereon; and an exhaust pipe (21 to 24), into which an exhaust gas passing through the through-hole (11 to 14) flows. The exhaust component (100, 100a to 100i) further includes a cylindrical portion (4, 4a to 4c) housing therein a catalyst. The exhaust component (100, 100a to 100i) further includes an intermediate portion (3, 3a, 3b) disposed, in the exhaust component (100, 100a to 100i), downstream of the exhaust pipe (21 to 24) and upstream of the cylindrical portion (4, 4a to 4c). A cross-sectional area perpendicular to a flow direction of the exhaust gas in the intermediate portion (3, 3a, 3b) increases toward a downstream end. The intermediate portion (3, 3a, 3b) includes, on a wall portion (31) forming the intermediate portion (3, 3a, 3b), a curved portion (32, 32a to 32d) including two or more bending points (321) where curvatures change. [Selected Drawing] FIG. 3

Description

BACKGROUNDThe present disclosure relates to an exhaust component.Japanese Unexamined Utility Model Application Publication No. H0 5-38316 discloses a manifold converter including a tubular casing for containing a catalyst. The manifold converter further includes an upstream diffuser and a downstream diffuser. The upstream diffuser is welded on an upper opening portion of the tubular casing and coupled to an exhaust manifold. The downstream diffuser is welded on a lower opening portion of the tubular casing. At a lower opening part of the upstream diffuser, a reinforcement flange bent inward is integrally formed on an entire circumference of the lower opening part. The reinforcement flange increases stiffness of the upstream diffuser, thereby to inhibit the lower opening part from deforming due to heat of an exhaust gas.SUMMARYIn the aforementioned manifold converter, a thermal expansionalong a flow direction of the exhaust gas occurs. Fixation of the manifold converter to other components leads to restriction of the thermal expansion, and thus a thermal stress is generated and applied to the manifold converter. The aforementioned manifold converter has a drawback that the thermal stress may cause damages or breakages of the upstream diffuser having a fragile portion, such as a portion with a narrower diameter than its surrounding portions, or a portion with a relatively lower stiffness.It is desirable that one aspect of the present disclosure provides atechnique of inhibiting a damage to an exhaust component caused by athermal stress generated due to a thermal expansion along a flow direction of an exhaust gas.In one aspect of the present disclosure, an exhaust component forming an exhaust flow path that introduces an exhaust gas from an internal combustion engine, comprises an exhaust manifold, a cylindrical portion, and an intermediate portion. The exhaust manifold comprises: a flange comprising at least one through-hole that is formed thereon and serves as an inflow port, into which an exhaust gas from the internal combustion engine flows; and at least one exhaust pipe, into which the exhaust gas passing through the at least one through-hole flows. The cylindrical portion is disposed downstream of the exhaust manifold and houses therein a catalyst that purifies the exhaust gas. The intermediate portion is disposed, in the exhaust component, downstream of the at least one exhaust pipe and upstream of the cylindrical portion. A crosssectional area perpendicular to a flow direction of the exhaust gas in the intermediate portion increases toward a downstream end. Further, the intermediate portion comprises, on a wall portion forming the intermediate portion, a curved portion comprising two or more bending points where curvatures change.With this configuration, the curved portion is provided on the intermediate portion susceptible to a damage from a thermal stress generated due to a restriction of the thermal expansion along the flow direction of the exhaust gas in the exhaust component. Accordingly, if the generated thermal stress is applied to the intermediate portion, such thermal stress is easily distributed to the two or more bending points provided on the curved portion. This achieves reduction in a damage to the exhaust component caused by the thermal stress generated due to the thermal expansion along the flow direction of the exhaust gas.In one aspect of the present disclosure, the curved portion may be a recess formed by recessing a part of the wall portion inwardly. With this configuration, the recess formed on the intermediate portion achieves reduction in a damage to the exhaust component caused by the thermal stress. A recess formed on an upstream part of the intermediate portion with a relatively smaller cross-sectional area is particularly effective at reduction in thermal stress to be applied to the intermediate portion.In one aspect of the present disclosure, the curved portion may be a projection protruding outward from a part of the wall portion. With this configuration, the projection formed on the intermediate portion achieves reduction in a damage to the exhaust component caused by the thermal stress. A projection formed on an upstream part of the intermediate portion with a relatively smaller cross-sectional area is particularly effective at reduction in thermal stress to be applied to the intermediate portion.In one aspect of the present disclosure, the flange may be a platelike member. The at least one through-hole may comprise two or more through-holes. An array direction along the two or more through-holes arrayed may indicate a longitudinal direction of the flange. The cylindrical portion may be arranged such that, when the exhaust component is projected onto a first virtual plane extending along a plane where the two or more through-holes of the flange are formed, a central axis of the cylindrical portion is displaced from a first center line passing through a center in the longitudinal direction of the flange, the first center line being orthogonal to the longitudinal direction. The curved portion may be positioned on an area of the intermediate portion situated on a first center line side.With this configuration, the central axis of the cylindrical portion is displaced from the first center line on the first virtual plane. In thiscase, the thermal stress generated due to the thermal expansion along the flow direction of the exhaust gas in the exhaust component tends to be applied to an area of the intermediate portion on the first center line side. In the configuration in which the cylindrical portion is arranged as described above, the curved portion is positioned in the area of the intermediate portion on the first center line side where the thermal stress tends to be applied. This configuration achieves reduction in the thermal stress to be applied to the intermediate portion.In one aspect of the present disclosure, the flange may be a platelike member. The at least one through-hole may comprise two or more through-holes. The flange may have a longitudinal direction and a short direction. The longitudinal direction may be an array direction along the two or more through-holes arrayed. The short direction may be orthogonal to the longitudinal direction and along a plane where the two or more through-holes of the flange are formed. The cylindrical portion may be arranged such that, when the exhaust component is projected onto the second virtual plane that is along the short direction and orthogonal to the first virtual plane extending along the plane where the two or more through-holes of the flange are formed, the central axis of the cylindrical portion may be tilted relative to the second center line that passes through a center of the short direction of the flange and is orthogonal to the short direction. The curved portion may be positioned in an area of the intermediate portion situated on a flange side.With this configuration, the central axis of the cylindrical portion is tilted relative to the second center line on the second virtual plane. In this case, the thermal stress generated due to the thermal expansion along the flow direction of the exhaust gas in the exhaust component tends to be applied to an area of the intermediate portion on the flange side. In the configuration in which the cylindrical portion is arranged as describedabove, the curved portion is positioned in the area of the intermediate portion on the flange side where the thermal stress tends to be applied. This configuration achieves reduction in the thermal stress to be applied to the intermediate portion.In one aspect of the present disclosure, the flange may be a platelike member. The at least one through-hole may comprise two or more through-holes. An array direction along the two or more through-holes arrayed may indicate a longitudinal direction of the flange. A direction orthogonal to the longitudinal direction and along a plane where the two or more through-holes of the flange are formed may indicate a short direction of the flange. The cylindrical portion may be arranged such that, when the exhaust component is projected onto the first virtual plane along the plane where the two or more through-holes of the flange are formed, a central axis of the cylindrical portion is displaced from the first center line that passes through a center of the longitudinal direction of the flange and is orthogonal to the longitudinal direction. Further, the cylindrical portion may be arranged such that, when the exhaust component is projected onto the second virtual plane that is orthogonal to the first virtual plane and along the short direction, the central axis of the cylindrical portion is tilted relative to the second center line that passes through the center of the short direction of the flange and is orthogonal to the short direction. The curved portion may be positioned in an area of the intermediate portion situated on a first center line side, and also in an area of the intermediate portion situated on a flange side.With this configuration, the central axis of the cylindrical portion is displaced from the first center line on the first virtual plane, and also tilted relative to the second center line on the second virtual plane. In this case, the thermal stress generated due to the thermal expansion along the flow direction of the exhaust gas in the exhaust component tends tobe applied to an area of the intermediate portion on the first center line side and also on the flange side. In the configuration in which the cylindrical portion is arranged as described above, the curved portion is positioned in the area of the intermediate portion where the thermal stress tends to be applied to the first center line side and also on the flange side. This configuration achieves reduction in the thermal stress to be applied to the intermediate portion.In one aspect of the present disclosure, the curved portion mayhave a shape extending along a circumferential direction of the intermediate portion. With this configuration, the curved portion can easily keep stiffness of a surrounding portion of the intermediate portion where the curved portion is provided while attempting to distribute stress on the intermediate portion, compared with a configuration in which a curved portion extends along the flow direction of the exhaust gas.In one aspect of the present disclosure, the curved portion may becurved in an arc-shape along the circumferential direction of the intermediate portion. With this configuration, it is easier for the curved portion to evenly distribute stress on the intermediate portion, compared with a configuration in which a curved portion linearly extends in a circumferential direction of the intermediate portion.BRIEF DESCRIPTION OF THE DRAWINGSAn example embodiment of the present disclosure will bedescribed hereinafter by way of example with reference to the accompanying drawings, in which:FIG. 1 is a front view of an exhaust component;FIG. 2 is a side view of the exhaust component;FIG. 3 is a perspective rear view of the exhaust component;FIG. 4 is a top view of the exhaust component transparently showing a part of an exhaust manifold;FIG. 5 is a top view of an upstream cone;FIG. 6 is a cross-sectional view taken along VI-VI of FIG. 5;FIG. 7A is a modification example of a catalyst case;FIG. 7B is a modification example of the exhaust manifold;FIG. 7C is another modification example of the exhaust manifold;FIG. 7D is still another modification example of the exhaust manifold;FIG. 8A is a schematic view of a first arrangement state of the exhaust component in the present embodiment;FIG. 8B is a schematic view of a second arrangement state of the exhaust component in the present embodiment;FIG. 8C is a schematic view of a modification example of an arrangement state of the exhaust component;FIG. 8D is a schematic view of another modification example of the arrangement state of the exhaust component;FIG. 8E is a schematic view of still another modification example of the arrangement state of the exhaust component;FIG. 9A is a schematic view of an exhaust component comprising two catalyst cases arranged in parallel to each other;FIG. 9B is a schematic view of an exhaust component comprising two catalyst cases arranged perpendicular to each other;FIG. 10 is a diagram of a configuration, in which two curved portions are arranged in parallel to each other on the upstream cone;FIG. 11 is a cross-sectional view taken along XI-XI of FIG. 10;andFIG. 12 is a diagram of a configuration, in which two curved portions are arrayed on the upstream cone to be spaced in a circumferential direction.DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0018] 1. Configuration1-1. Overall ConfigurationAn exhaust component 100 shown in FIG. 1 to FIG. 4 forms a part of an exhaust flow path for introducing, toward an outside of a vehicle, exhaust gases discharged from respective two or more cylinders, for example, four cylinders, of an internal combustion engine of the vehicle. The exhaust component 100 comprises an upstream flange 1, an exhaust manifold 2, an upstream cone 3, a catalyst case 4, a downstream cone 5, a tubular member 6, and a downstream flange 7.The upstream flange 1 is a plate-like member made of metal. Theupstream flange 1 is partly fixed to the internal combustion engine of the vehicle or a portion on an internal combustion engine side thereof. As shown in FIG. 3, the upstream flange 1 includes two or more through-holes, for example, four through-holes 11 to 14 formed thereon. The four through-holes 11 to 14 serve as inflow ports, into which exhaust gases from the respective cylinders of the internal combustion engine flow. The upstream flange 1 has a shape extending in an array direction, along which the four through-holes 11 to 14 are arrayed. The through-holes 11 to 14 are coupled to respective upstream ends of four exhaust pipes 21 to 24 (described below), as shown in FIG. 1.In the following description, the array direction along the fourthrough-holes 11 to 14 arrayed indicates a longitudinal direction of the upstream flange 1. Also, a direction orthogonal to the longitudinal direction and along a flange plane 15 where the four through-holes 11 to14 of the upstream flange 1 are formed indicates a short direction of the upstream flange 1. Further, a surface along the flange plane 15 indicates a first virtual plane P1 shown in FIG. 1. A surface orthogonal to the first virtual plane P1 and along the short direction indicates a second virtual plane P2 shown in FIG. 2. The exhaust gases enter the upstream flange 1 to flow through the exhaust component 100, as indicted by an arrow G of FIG. 2.The exhaust manifold 2 is a metal member, and is coupled to the upstream flange 1, as shown in FIG. 1. In the present embodiment, the exhaust manifold 2 converges four exhaust flow paths corresponding to the four cylinders to form a single exhaust flow path, so that the exhaust gases discharged from the respective cylinders of the internal combustion engine are collected together. The exhaust manifold 2 comprises the four exhaust pipes 21 to 24 and a junction portion 25. The exhaust gases pass through the four through-holes 11 to 14 to flow into the respective exhaust pipes 21 to 24. The junction portion 25 is an exhaust pipe for forming an exhaust flow path for collecting together the exhaust gases discharged from the four exhaust pipes 21 to 24.The upstream cone 3 is disposed downstream of the exhaust manifold 2, and also upstream of the catalyst case 4, which will be described below. The upstream cone 3 couples the exhaust manifold 2 and the catalyst case 4. Specifically, the upstream cone 3 is a metal member, and is coupled to a downstream end of the junction portion 25 of the exhaust manifold 2. The upstream cone 3 has a cylindrical shape and is formed to gradually increase a diameter toward its downstream end in the exhaust flow path. In other words, a cross section of the upstream cone 3 perpendicular to a flow direction of the exhaust gas (hereinafter, simply referred to as "cross section") increases its crosssectional area toward the downstream end. The upstream cone 3 mayhave a cylindrical shape formed by butt-joining two components divided along the flow direction of the exhaust gas. The upstream cone 3 forms an exhaust flow path for the exhaust gas discharged from the junction portion 25. As shown in FIG. 3 to FIG. 6, the upstream cone 3 comprises, on a wall portion 31 forming the upstream cone 3, a curved portion 32 comprising two or more bending points 321 where curvatures of a cross section of the wall portion 31 sharply change. Each bending point 321 indicates a sharp-bent point from a straight state (that is, the curvature is zero) to a bent state, in which a specific curvature or more can be obtained. That is, the curved portion 32 is a section having a bent shape and provided on the upstream cone 3, regardless of a shape required to introduce the exhaust gas into the upstream cone 3 in the flow direction of the exhaust gas. In other words, the curved portion 32 is provided on the upstream cone 3, not for a main purpose of introducing the exhaust gas to flow in the flow direction.As shown in FIG. 6, the curved portion 32 is a recess formed by recessing a part of the wall portion 31 inwardly. Alternatively, the curved portion 32 may be a projection protruding outward from a part of the wall portion 31. Specifically, the curved portion 32 including the two or more bending points 321 is a recess or a projection. As shown in FIG. 5, the curved portion 32 is a recess arcuately extending along a circumferential direction of the upstream cone 3. In other words, the two or more bending points 321 formed on the curved portion 32 arcuately extend along the circumferential direction of the upstream cone 3. The curved portion 32 has approximately 1 / 4 of the entire circumferential length of the upstream cone 3. In other words, the curved portion 32 is provided on the upstream cone 3 to extend across an area of a circular sector with a central angle of approximately 90 degrees of the upstream cone 3. The curved portion 32 is provided in a specific area of theupstream cone 3. The specific area indicates an area of the upstream cone 3, which is determined depending on the arrangement of the catalyst case 4 with respect to the upstream flange 1, and has a small section modulus. The section modulus indicates a resistance against a stress applied when a cross section is bent. The specific area where the curved portion 32 is provided will be detailed below.The catalyst case 4 is a metal member, and is coupled to the downstream end of the upstream cone 3, as shown in FIG. 1 to FIG. 3. The catalyst case 4 has a cylindrical shape and houses therein a cylindrical catalyst (not shown) for purifying the exhaust gas.The downstream cone 5 is a metal member, and is coupled to a downstream end of the catalyst case 4. The downstream cone 5 has a cylindrical shape and is formed to gradually reduce a diameter toward its downstream end in the exhaust flow path. The downstream cone 5 may have a cylindrical shape formed by butt-joining two components divided along the flow direction of the exhaust gas. The downstream cone 5 forms an exhaust flow path for an exhaust gas purified by the catalyst.The tubular member 6 is a metal member, and is coupled to the downstream end of the downstream cone 5. The tubular member 6 has a cylindrical shape. The tubular member 6 forms an exhaust flow path for the exhaust gas discharged from the downstream cone 5.The downstream flange 7 is a plate-like member made of metal. The downstream flange 7 includes a through-hole that permits the tubular member 6 to be inserted thereinto and is fixed to the tubular member 6 penetrating the through-hole of the downstream flange 7. The downstream flange 7 is partly fixed to the internal combustion engine or a portion on the internal combustion engine side thereof.1-2. Arrangement of Catalyst Case and Position of Curved Portion In the present embodiment, the catalyst case 4 is arranged with respect to the upstream flange 1 of the exhaust component 100 as described below. Relative to the arrangement of the catalyst case 4, the curved portion 32 is positioned in a specific area (described below) of the upstream cone 3.As shown in FIG. 1, when the exhaust component 100 is projected onto the first virtual plane P1, the catalyst case 4 is situated in a first arrangement state, in which a central axis A of the catalyst case 4 is displaced from a first center line B1. The first center line B1 indicates a line that passes through a center in the longitudinal direction of the upstream flange 1, and is orthogonal to the longitudinal direction. The arrangement of the central axis A displaced from the first center line B1 includes an arrangement in which the central axis A is spaced in parallel to the first center line B1, and an arrangement in which the central axis A is tilted relative to the first center line B1. In the present embodiment, the catalyst case 4 is in the arrangement state in which the central axis A is spaced in parallel to the first center line B1.As shown in FIG. 2, when the exhaust component 100 is projected onto the second virtual plane P2, the catalyst case 4 is situated in a second arrangement state, in which the central axis A of the catalyst case 4 is tilted with respect to the second center line B2. In other words, in the second arrangement state, the central axis A is not parallel to the second center line B2. The second center line B2 indicates a line that passes through the center in the short direction of the upstream flange 1 and is orthogonal to the short direction. In the present embodiment, the catalyst case 4 is positioned such that the center axis A intersects the second center line B2 at an angle slightly greater than a right angle and also isspaced further away from the first virtual plane P1 toward the downstream end of the catalyst case 4.As mentioned above, the catalyst case 4 is arranged in the first arrangement state and also the second arrangement state. Accordingly, as shown in FIG. 4, the specific area of the upstream cone 3 indicates an overlapping area of the upstream cone 3, in which a first area C1 and a second area C2 overlap each other. The first area C1 is an area of the upstream cone 3 situated on a first center line B1 side. The second area C2 is an area of the upstream cone 3 situated on an upstream flange 1 side. The curved portion 32 is positioned in the overlapping area of the first area C1 and the second area C2. In other words, the curved portion 32 is positioned, on the upstream cone 3, in the vicinity of the first center line B1, specifically, in an area of the upstream cone 3 facing the first center line B1.Specifically, the first area C1 of the upstream cone 3 indicates an area of the upstream cone 3 situated on the first center line B1 side when the upstream cone 3 is divided by a line parallel to the second center line B2, as viewed from an upstream end of the exhaust component 100 in FIG. 4. The following describes up-down directions from an upper side through a lower side, and right-left directions from a left side through a right side, based on directions shown in FIG. 5. In other words, the first area C1 of the upstream cone 3 indicates a left portion of two portions (right and left portions) of the upstream cone 3 that are virtually divided in the right-left directions, as viewed from the top of the upstream cone 3 in FIG. 5.In the present embodiment, the exhaust component 100 is fixed to other components through the upstream flange 1 and the downstream flange 7. In the first arrangement state of the catalyst case 4 as shown in FIG. 1, if a thermal expansion along the flow direction of the exhaust gasin the exhaust component 100 is restricted by such fixation, a load is applied in a compression direction indicated by an arrow in FIG. 1, and thereby the exhaust component 100 is easily deformed. In other words, when the central axis A of the catalyst case 4 is arranged to be displaced from the first center line B1 in the longitudinal direction of the upstream flange 1 on the first virtual plane P1, a reaction force F1 (shown in FIG. 1) of a first portion of the upstream flange 1 becomes smaller than a reaction force F2 (shown in FIG. 1) of a second portion of the upstream flange 1. The first portion is a portion having a length L1 of the upstream flange 1 from the central axis A. The second portion is a portion having a length L2 of the upstream flange 1 from the central axis A. The reaction force herein indicates a force that the upstream flange 1 receives from the internal combustion engine. Also, the reaction force opposes a force that the upstream flange 1 applies to the internal combustion engine due to the thermal expansion along the flow direction of the exhaust gas in the exhaust component 100. Accordingly, a load is applied to the first portion of the upstream flange 1 such that the exhaust manifold 2 and the catalyst case 4 approach each other. As a result, the exhaust component 100 is easily deformed such that a portion between the exhaust manifold 2 and the catalyst case 4 is curved. Owing to the deformation of the exhaust component 100, a thermal stress generated due to a restriction of the thermal expansion along the flow direction of the exhaust gas tends to be applied to the first area C1 of the upstream cone 3.Further, the second area C2 of the upstream cone 3 indicates an area of the upstream cone 3 situated on an upstream flange 1 side (i.e., closer to the upstream flange 1) when the upstream cone 3 is divided by a line parallel to the first virtual plane P1, as viewed from the upstream end of the exhaust component 100 in FIG. 4. In other words, the second area C2 of the upstream cone 3 indicates an upper portion of two portions(upper and lower portions) of the upstream cone 3 that are virtually divided in the up-down directions, as viewed from the top of the upstream cone 3 in FIG. 5.As described above, the exhaust component 100 is fixed to other components through the upstream flange 1 and the downstream flange 7. In the second arrangement state of the catalyst case 4 as shown in FIG. 2, if the thermal expansion along the flow direction of the exhaust gas in the exhaust component 100 is restricted by such fixation, a load is applied in a compression direction indicated by an arrow in FIG. 2, and thereby the exhaust component 100 is easily deformed. Owing to the deformation of the exhaust component 100, the thermal stress generated due to the restriction of the thermal expansion along the flow direction of the exhaust gas tends to be applied to the second area C2 of the upstream cone 3.That is, when the catalyst case 4 is in the first arrangement state and the second arrangement state, the first area C1 and the second area C2 are fragile portions of the upstream cone 3 susceptible to a damage from the thermal stress generated due to the restriction of the thermal expansion along the flow direction of the exhaust gas. In other words, the first area C1 and the second area C2 of the upstream cone 3 are areas where the thermal stress generated due to the restriction of the thermal expansion along the flow direction of the exhaust gas tends to be applied. These areas are defined in accordance with arrangement of the catalyst case 4 with respect to the upstream flange 1. Specifically, the first area C1 and the second area C2 of the upstream cone 3 each have a small section modulus.3. EffectsThe embodiment as detailed above produces the following effects.(3a) In the present embodiment, the curved portion 32 comprising the two or more bending points 321 is provided on the upstream cone 3 having a portion with a narrower diameter than that of the catalyst case 4. Even if the exhaust component 100 fixed to other components through the upstream flange 1 and the downstream flange 7 restricts the thermal expansion along the flow direction of the exhaust gas in the exhaust component 100, and the resulting thermal stress generated due to the thermal expansion is applied to the upstream cone 3, such thermal stress is easily distributed to the two or more bending points 321 provided on the curved portion 32. This achieves reduction in a damage to the upstream cone 3 of the exhaust component 100 caused by the thermal stress generated due to the thermal expansion along the flow direction of the exhaust gas.(3b) In the present embodiment, the catalyst case 4 is in the first arrangement state and also the second arrangement state. Accordingly, the thermal stress generated due to the thermal expansion along the flow direction of the exhaust gas in the exhaust component 100 is more easily applied to the first area C1 and the second area C2 of the upstream cone 3. In the configuration in which the catalyst case 4 is arranged as described above, the curved portion 32 is positioned in the overlapping area of the first area C1 and the second area C2 where the thermal stress tends to be applied. This configuration achieves reduction in the thermal stress to be applied to the upstream cone 3.(3c) In the present embodiment, the curved portion 32 is a recess formed by recessing a part of the wall portion 31 inwardly. The recess formed on the upstream cone 3 achieves reduction in a damage to the exhaust component 100 caused by the thermal stress. A recess formed onan upstream part of the upstream cone 3 with a relatively smaller crosssectional area is particularly effective at reduction in the thermal stress to be applied to the upstream cone 3.(3d) In the present embodiment, the curved portion 32 extends along a circumferential direction of the catalyst case 4. Accordingly, the curved portion 32 can easily keep stiffness of a surrounding portion of the upstream cone 3 where the curved portion 32 is provided while attempting to distribute stress on the upstream cone 3, compared with a configuration in which a curved portion extends along the flow direction of the exhaust gas. Further, in the present embodiment, the curved portion 32 is curved in the arc-shape along the circumferential direction of the catalyst case 4. Accordingly, it is easier for the curved portion 32 to evenly distribute stress on the cylindrical upstream cone 3, compared with a configuration in which a curved portion linearly extends in a circumferential direction of the cylindrical upstream cone 3.The upstream flange 1 corresponds to an example of a flange, and the upstream cone 3 corresponds to an example of an intermediate portion. In the present embodiment, the entire catalyst case 4 corresponds to an example of a cylindrical portion.4. Other EmbodimentsAlthough the embodiments of the present disclosure have been described above, it is to be understood that the present disclosure is not limited to the above-described embodiments but may be in various forms within the technical scope of the present disclosure.(4a) In the aforementioned embodiments, an example configuration is described in which the upstream flange 1 including the four through-holes 11 to 14 has a length extending in the array direction along the four through-holes 11 to 14. However, a shape of the upstream flange and the number of the through-holes thereof are not limited bythose of the embodiments. For example, the number of the through-holes may be five or more, or may be three or less.(4b) In the aforementioned embodiments, an example configuration is described in which the exhaust component 100 comprises the exhaust manifold 2 including the four exhaust pipes 21 to 24, further comprises the upstream cone 3 and the catalyst case 4. However, the exhaust component 100 of the present disclosure is not limited by the aforementioned embodiment. Although an illustration is omitted, exhaust components 100a to 100d (described below) in FIG. 7A to FIG. 7D also each comprise the curved portion 32 in a specific area susceptible to a damage from a thermal stress generated due to the restriction of the thermal expansion along the flow direction of the exhaust gas.For example, as shown in FIG. 7A, the exhaust component 100a may comprise an upstream flange 1a, an exhaust manifold 2a, and a catalyst case 4a. The upstream flange 1a includes three through-holes. The exhaust manifold 2a comprises three exhaust pipes coupled to the three through-holes formed on the upstream flange 1a to form an exhaust flow path. In this exhaust path flow, the exhaust gases discharged from the three exhaust pipes are collected together. The catalyst case 4a has an upstream end coupled to the exhaust manifold 2a, and is shaped such that an upstream part of the catalyst case 4a gradually reduces a diameter toward the upstream end. In other words, in a configuration of an exhaust component without the upstream cone 3, the catalyst case 4a may have a portion in shape corresponding to the upstream cone 3 of the present embodiment.Further, for example, as shown in FIG. 7B, the exhaust component 100b may comprise an upstream flange 1b, an exhaust manifold 2b, the upstream cone 3, and the catalyst case 4. The upstreamflange 1b includes one through-hole that allows exhaust gases from two or more cylinders of the internal combustion engine to be combined. The exhaust manifold 2b is formed by one exhaust pipe coupled to one through-hole formed on the upstream flange 1b. The exhaust manifold 2b may be formed by butt-joining two components divided along the flow direction of the exhaust gas. Specifically, the exhaust manifold 2b may have a cylindrical shape formed by butt-joining two components each having a U-shaped cross section perpendicular to the flow direction of the exhaust gas.Further, for example, as shown in FIG. 7C, the exhaust component 100c may comprise the upstream flange 1b, an exhaust manifold 2c, and the catalyst case 4. The exhaust manifold 2c comprises one exhaust pipe coupled to one through-hole formed on the upstream flange 1b. The exhaust manifold 2c has a downstream end coupled to the catalyst case 4, and is shaped such that a downstream part of the exhaust manifold 2c gradually enlarges a diameter toward the downstream end. In other words, in a configuration of an exhaust component without the upstream cone 3, the exhaust manifold 2c may comprise a portion in shape corresponding to the upstream cone 3. The exhaust manifold 2c may be formed by butt-joining two components divided along the flow direction of the exhaust gas.Further, as shown in FIG. 7D, the exhaust component 100d may comprise an exhaust manifold 2d. The exhaust manifold 2d may be formed such that the two components divided along the flow direction of the exhaust gas are orientated in a direction different from that of the exhaust manifold 2c in FIG. 7C. The exhaust manifold 2d comprises one exhaust pipe coupled to one through-hole formed on the upstream flange 1b. The exhaust manifold 2d has a downstream end coupled to thecatalyst case 4, and is shaped such that a downstream part of the exhaust manifold 2d gradually enlarges a diameter toward the downstream end.(4c) In the aforementioned embodiments, a mounting state in which the exhaust component 100 is mounted on a vehicle is described. In the mounting state, the catalyst case 4 and the upstream flange 1 are in a first arrangement state (shown in a schematic diagram of FIG. 8A) and also in a second arrangement state (shown in a schematic diagram of FIG. 8B). However, the present disclosure is not limited to this mounting state. Although an illustration is omitted, exhaust components 100e to 100g (described below) in FIG. 8C to FIG. 8E also each comprise the curved portion 32 in specific areas susceptible to a damage from the thermal stress generated due to the restriction of the thermal expansion along the flow direction of the exhaust gas.For example, the catalyst case 4 may be in either the first arrangement state or the second arrangement state.Further, for example, in the mounting state of the exhaust component 100e as schematically shown in FIG. 8C, the catalyst case 4 may be in an arrangement state in which the central axis A of the catalyst case 4 is not displaced from the first center line B1 on the first virtual plane P1, and also in the second arrangement state shown in the schematic diagram of FIG. 8B. In other words, the catalyst case 4 may be in an arrangement state in which the central axis A of the catalyst case 4 conforms with the first center line B1 on the first virtual plane P1, and also in the second arrangement state shown in the schematic diagram of FIG. 8B.Further, for example, in the mounting state of the exhaust component 100f as schematically shown in FIG. 8D, the catalyst case 4 may be in an arrangement state in which the central axis A of the catalyst case 4 passes through the center in the longitudinal direction of theupstream flange 1 on the first virtual plane P1, and also in an arrangement state in which the central axis A is tilted relative to the first center line B1.Further, in the mounting state of the exhaust component 100g as schematically shown in FIG. 8E, the catalyst case 4 may be in an arrangement state in which an opening formed on a downstream exhaust flow path of the catalyst case 4, more specifically, an opening of the downstream cone 5 at its end where the exhaust gas is discharged does not face the internal combustion engine.(4d) In the aforementioned embodiments, an example configuration is described in which the exhaust component 100 comprises one catalyst case 4. However, the exhaust component of the present disclosure is not limited by the aforementioned embodiment. For example, as shown in FIG. 9A, an exhaust component 100h may comprise two catalyst cases 4b, 4c arranged in parallel to each other. Alternatively, for example, as shown in FIG. 9B, the exhaust component 100i may comprise the two catalyst cases 4b, 4c perpendicular to each other. Although an illustration is omitted, each of the exhaust components 100h, 100i of FIG. 9A and FIG. 9B also comprises the curved portion 32 in a specific area between the upstream flange 1 and the catalyst case 4b directly coupled to the upstream flange 1. Also, the specific area is susceptible to a damage from the thermal stress generated due to the restriction of the thermal expansion along the flow direction of the exhaust gas.(4e) In the aforementioned embodiments, an example configuration is described in which one curved portion 32 is provided on the upstream cone 3 to extend in a circumferential direction of the upstream cone 3a. However, the curved portion provided on the upstream cone is not limited by the aforementioned embodiment.For example, as shown in FIG. 10 and FIG. 11, two curved portions 32a, 32b may be provided on the upstream cone 3a to be spaced from each other along the flow direction of the exhaust gas. Each of the two curved portions 32a, 32b has a shape extending along the circumferential direction of the upstream cone 3a.Further, for example, as shown in FIG. 12, two curved portions 32c, 32d may be provided on an upstream cone 3b spaced from each other along a circumferential direction of the upstream cone 3b.(4f) Functions of one constituent element in the aforementioned embodiments may be divided and separately performed by a plurality of constituent elements, or functions of a plurality of constituent elements may be integrated and performed by one constituent element. Part of the configuration in the aforementioned embodiments may be omitted. At least part of the configuration in the aforementioned embodiments may be added to or replaced by the configuration in the aforementioned other embodiments. Any modes included in the technical ideas specified by the languages of the claims are embodiments of the present disclosure.

Claims

1. An exhaust component (100, 100a to 100i) forming an exhaust flow path that introduces an exhaust gas from an internal combustion engine, the exhaust component (100, 100a to 100i) comprising: an exhaust manifold (2, 2a to 2d) comprising: a flange (1, 1a, 1b) comprising at least one through-hole (11 to 14) that is formed thereon and serves as an inflow port, into which an exhaust gas from the internal combustion engine flows, and at least one exhaust pipe (21 to 24), into which the exhaust gas passing through the at least one through-hole (11 to 14) flows; a cylindrical portion (4, 4a to 4c) disposed downstream of the exhaust manifold (2, 2a to 2d) and housing therein a catalyst that purifies the exhaust gas; an intermediate portion (3, 3a, 3b) disposed, in the exhaust component (100, 100a to 100i), downstream of the at least one exhaust pipe (21 to 24) and upstream of the cylindrical portion (4, 4a to 4c), a cross-sectional area perpendicular to a flow direction of the exhaust gas in the intermediate portion (3, 3a, 3b) increasing toward a downstream end; and wherein the intermediate portion (3, 3a, 3b) comprises, on a wall portion (31) forming the intermediate portion (3, 3a, 3b), a curved portion (32, 32a to 32d) comprising two or more bending points (321) where curvatures change.

2. The exhaust component (100, 100a to 100i) as claimed in claim 1, wherein the curved portion (32, 32a to 32d) is a recess formed by recessing a part of the wall portion (31) inwardly.

3. The exhaust component (100, 100a to 100i) as claimed in claim 1, wherein the curved portion (32, 32a to 32d) is a projection protruding outward from a part of the wall portion (31).

4. The exhaust component (100, 100a to 100i) as claimed in any one of claims 1 to 3, wherein the flange (1, 1a, 1b) is a plate-like member, wherein the at least one through-hole (11 to 14) comprises two or more through-holes (11 to 14), wherein an array direction along the two or more through-holes (11 to 14) arrayed indicates a longitudinal direction of the flange (1, 1a, 1b), wherein, the cylindrical portion (4, 4a to 4c) is arranged such that, when the exhaust component (100, 100a to 100i) is projected onto a first virtual plane (P1) extending along a plane (15) where the two or more through-holes (11 to 14) of the flange (1, 1a, 1b) are formed, a central axis (A) of the cylindrical portion (4, 4a to 4c) is displaced from a first center line (B1) passing through a center in the longitudinal direction of the flange (1, 1a, 1b), the first center line (B1) being orthogonal to the longitudinal direction, and wherein the curved portion (32, 32a to 32d) is positioned in an area of the intermediate portion (3, 3a, 3b) situated on a first center line (B1) side.

5. The exhaust component (100, 100a to 100i) as claimed in any one of claims 1 to 3, wherein the at least one through-hole (11 to 14) comprises two or more through-holes (11 to 14), wherein the flange (1, 1a, 1b) is a plate-like member, wherein the flange (1, 1a, 1b) has a longitudinal direction and a short direction, the longitudinal direction being an array direction along the two or more through-holes (11 to 14) arrayed, the short direction being orthogonal to the longitudinal direction and along a plane (15) where the two or more through-holes (11 to 14) of the flange (1, 1a, 1b) are formed, wherein the cylindrical portion (4, 4a to 4c) is arranged such that, when the exhaust component (100, 100a to 100i) is projected onto the second virtual plane (P2) that is along the short direction and orthogonal to the first virtual plane (P1) extending along the plane (15), a central axis (A) of the cylindrical portion (4, 4a to 4c) is tilted relative to the second center line (B2) that passes through a center of the short direction of the flange (1, 1a, 1b) and is orthogonal to the short direction, and wherein the curved portion (32, 32a to 32d) is positioned in an area of the intermediate portion (3, 3a, 3b) situated on a flange (1, 1a, 1b) side.

6. The exhaust component (100, 100a to 100i) as claimed in any one of claims 1 to 3, wherein the flange (1, 1a, 1b) is a plate-like member, wherein the at least one through-hole (11 to 14) comprises two or more through-holes (11 to 14), wherein an array direction along the two or more through-holes (11 to 14) arrayed indicates a longitudinal direction of the flange (1, 1a, 1b), wherein a direction orthogonal to the longitudinal direction and along a plane (15) where the two or more through-holes (11 to 14) of the flange (1, 1a, 1b) are formed indicates a short direction of the flange (1, 1a, 1b), wherein the cylindrical portion (4, 4a to 4c) is arranged such that: when the exhaust component (100, 100a to 100i) is projected onto the first virtual plane (P1) along the plane (15), a central axis (A) of the cylindrical portion (4, 4a to 4c) is displaced from the first center line (B1) that passes through a center of the longitudinal direction of the flange (1, 1a, 1b) and is orthogonal to the longitudinal direction, and when the exhaust component (100, 100a to 100i) is projected onto the second virtual plane (P2) that is orthogonal to the first virtual plane (P1) and along the short direction, the central axis (A) is tilted relative to the second center line (B2) that passes through a center of the short direction of the flange (1, 1a, 1b) and is orthogonal to the short direction, and wherein the curved portion (32, 32a to 32d) is positioned in an area of the intermediate portion (3, 3a, 3b) situated on a first center line (B1) side, and also in an area of the intermediate portion (3, 3a, 3b) situated on a flange (1, 1a, 1b) side.

7. The exhaust component (100, 100a to 100i) as claimed in any one of claims 1 to 6, wherein the curved portion (32, 32a to 32d) has a shape extending along a circumferential direction of the intermediate portion (3, 3a, 3b).

8. The exhaust component (100, 100a to 100i) as claimed in any one of claims 1 to 7, wherein the curved portion (32, 32a to 32d) is curved in an arc-shape along the circumferential direction of the intermediate portion (3, 3a, 3b).