Motorcycle exhaust system

Abstract

To facilitate manufacture of a metal catalyst carrier by improving purification performance for exhaust gas and efficiently preventing a catalyst case containing the metal catalyst carrier from coming into contact with a ground surface.SOLUTION: An exhaust device for a motor cycle of the present invention has an engine and an exhaust pipe connected to the exhaust port of the engine. The exhaust pipe has a metal catalyst carrier, a catalyst case that houses the metal catalyst carrier and is disposed below the engine, and a pipe that allows the exhaust port and the catalyst case to communicate with each other. The metal catalyst carrier has an inner wall that defines a plurality of passage sections, a surface of the inner wall is coated with a catalyst, and an outer periphery of the metal catalyst carrier abuts on an inner periphery of the catalyst case. A plurality of corrugated portions and a plurality of flat plate portions on the inner wall are stacked alternately one by one with their thickness directions aligned in a direction perpendicular to a flow direction. The catalyst case is disposed in an inclined posture that rises as it goes from front toward rear, and the metal catalyst carrier is formed into an inverted trapezoidal shape so that its width decreases as it goes from top toward bottom when viewed in the flow direction.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an exhaust system for a motorcycle having a metal catalyst carrier. [Background technology]

[0002] Motorcycles are provided with an exhaust system to smoothly discharge exhaust gas generated by the engine to the outside of the motorcycle. The exhaust system may be provided with a metal catalyst carrier to purify the exhaust gas. This metal catalyst carrier is a metal carrier that supports a catalyst. The exhaust system further has a catalyst case that houses the metal catalyst carrier. The catalyst case may be located below the engine and transmission due to layout restrictions on the motorcycle, such as vehicle width restrictions.

[0003] One example of such an exhaust system for a motorcycle is an exhaust system for a motorcycle having an exhaust gas purification catalyst device, the exhaust gas purification catalyst device having a honeycomb core (metal catalyst carrier) configured so that a catalyst is supported on a metal carrier, and a metal outer cylinder (catalyst case) that supports the honeycomb core internally, the carrier of the honeycomb core being configured so that multiple layers of metal foil-like flat and corrugated sheets are wound in a roll (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-147879 A Summary of the Invention [Problem to be solved by the invention]

[0005] In motorcycles (hereinafter referred to as "vehicle" as necessary), the engine is generally disposed in front of the transmission. Furthermore, in motorcycles, when the catalyst case and metal catalyst carrier of the exhaust device are disposed below the engine and transmission as described above, due to further constraints on the layout of the motorcycle, the lower ends of the engine and transmission may be inclined so as to rise upward from the front of the vehicle toward the rear of the vehicle, and the catalyst case and metal catalyst carrier may be disposed so as to incline along the inclination of the lower ends of the engine and transmission.

[0006] In such motorcycles, the front end of the catalyst case, which houses a metal catalyst carrier configured by winding multiple layers of flat and corrugated metal foil into a roll like the example of the exhaust system described above, may come into contact with the ground, particularly when the motorcycle banks while turning.

[0007] In particular, in recent motorcycles, there is a demand for reducing the amount of harmful substances contained in the exhaust gas, such as carbon monoxide, hydrocarbon compounds, nitrogen oxides, etc. In other words, there is a demand for improving the purification performance of the exhaust gas. In order to meet such demands, if the catalyst case housing the metal catalyst carrier is moved toward the front of the vehicle in order to reduce the path of the exhaust gas from the engine to the metal catalyst carrier, the catalyst case becomes more likely to come into contact with the ground for the reasons mentioned above.

[0008] In view of this situation, it is desirable to improve the exhaust gas purification performance of the exhaust system of a motorcycle, and to efficiently prevent the catalyst case housing the metal catalyst carrier from contacting the ground. Furthermore, it is desirable to improve the exhaust gas purification performance of the exhaust system manufactured by the method of manufacturing the exhaust system of a motorcycle, and to efficiently prevent the catalyst case housing the metal catalyst carrier from contacting the ground in the exhaust system manufactured by the method of manufacturing the exhaust system of a motorcycle, and to easily manufacture the metal catalyst carrier. [Means for solving the problem]

[0009] In order to solve the problem, an exhaust system for a motorcycle in one embodiment includes an engine having an exhaust port for discharging gas, and an exhaust pipe connected to the exhaust port so as to allow gas from the exhaust port to pass through, the exhaust pipe having a metal catalyst carrier arranged along the flow direction of gas passing through it, a catalyst case that houses the metal catalyst carrier and is arranged below the engine, and a pipe extending to connect the exhaust port of the engine and the catalyst case, the metal catalyst carrier has an inner wall that defines a plurality of passage sections extending along the flow direction, a catalyst is coated on the surface of the inner wall facing the passage sections, and the metal catalyst carrier is fitted into the catalyst case so that its outer periphery abuts against the inner periphery of the catalyst case.

[0010] In the exhaust system of the motorcycle described above, the inner wall of the metal catalyst carrier has a plurality of corrugated portions formed in a corrugated shape and a plurality of flat portions formed in a flat shape, the plurality of corrugated portions and the plurality of flat portions are arranged so that one of the plurality of corrugated portions and one of the plurality of flat portions are alternately stacked with their thickness directions aligned in a direction perpendicular to the flow direction, the catalyst case is arranged in an inclined position that rises upward as it moves from the front of the vehicle to the rear of the vehicle, and the metal catalyst carrier is formed in an inverted trapezoidal shape so that its width decreases from top to bottom when viewed in the flow direction. Effect of the Invention

[0011] In the exhaust system for a motorcycle according to one aspect, the performance of purifying exhaust gas can be improved, and the catalyst case housing the metal catalyst carrier can be efficiently prevented from coming into contact with the ground. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a side view that shows a schematic diagram of a motorcycle having an exhaust system according to one embodiment. [Diagram 2]FIG. 2 is a side view that shows a schematic view of a catalyst case and its surroundings in an exhaust pipe of an exhaust system according to one embodiment. [Diagram 3] FIG. 3 is a side view that shows a schematic view of a catalyst case and its surroundings of an exhaust pipe according to one embodiment, as viewed from the direction of arrow X in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line YY in FIG. [Diagram 5] FIG. 5 is a cross-sectional view taken along line ZZ in FIG. [Figure 6] FIG. 6 is a bottom perspective view that shows a schematic view of a metal catalyst carrier of an exhaust pipe according to one embodiment. [Figure 7] FIG. 7 is a flowchart for explaining a method for manufacturing an exhaust device for a motorcycle according to one embodiment. [Figure 8] FIG. 8 is a flow chart for explaining the steps of producing a metal catalyst support in a production method according to one embodiment. [Figure 9] FIG. 9 is a plan view that shows a schematic diagram of a strip material cut in a manufacturing process of a metal catalyst support according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An exhaust system for a motorcycle according to an embodiment and a method for manufacturing the same will be described below. In this specification, a motorcycle will be referred to as a "vehicle" as necessary.

[0014] In Figs. 1 to 6 used in the description of this specification, directions based on the vehicle are indicated as follows. In Figs. 1, 2, 5, and 6, the front and rear of the vehicle are indicated by single-sided arrows F and B, respectively. In Figs. 3, 4, and 6, the left and right when facing the front of the vehicle are indicated by single-sided arrows L and R, respectively. The vehicle width direction is indicated by single-sided arrows L and R. Furthermore, in Figs. 1 to 6, the top and bottom of the vehicle are indicated by single-sided arrows U and D, respectively.

[0015] In addition, the left and right directions refer to the left and right directions when facing the front of the vehicle. The horizontal direction refers to the direction along the front-rear and width directions of the vehicle. The upper and lower directions of the vehicle are sometimes simply called the upper and lower directions, respectively.

[0016] "Outline of motorcycle exhaust system" 1 to 6, an exhaust device 10 for a motorcycle according to this embodiment is generally configured as follows. As shown in Fig. 1, the exhaust device 10 has an engine 11. The engine 11 has an exhaust port 11a for discharging gas.

[0017] As shown in Figures 1 to 3, the exhaust device 10 has an exhaust pipe 20 that is connected to the exhaust port 11a so as to allow gas from the exhaust port 11a to pass therethrough. As shown in Figures 4 to 6, the exhaust pipe 20 has a metal catalyst carrier 30 that is arranged along the flow direction of the gas passing through it (indicated by a one-sided arrow P of a two-dot chain line in Figure 1).

[0018] 1 to 5, the exhaust pipe 20 has a catalyst case 21 that houses a metal catalyst carrier 30. The catalyst case 21 is disposed below the engine 11. The exhaust pipe 20 also has a pipe 22 that extends to communicate between the exhaust port 11a of the engine 11 and the catalyst case 21. This pipe 22 is located upstream in the flow direction of the exhaust pipe 20. Therefore, hereinafter, the pipe 22 will be referred to as an "upstream pipe" 22 as necessary.

[0019] As shown in Figures 4 to 6, the metal catalyst carrier 30 has a passage compartment group 40 consisting of a plurality of passage compartments 41a, 42a, 43a, and 44a extending along the flow direction. The metal catalyst carrier 30 has an inner wall 31 that defines the plurality of passage compartments 41a to 44a. A catalyst 32 is coated on a surface 31a of the inner wall 31 that faces the passage compartments 41a to 44a. The metal catalyst carrier 30 is fitted into the catalyst case 21 such that an outer circumferential portion 30a thereof abuts against an inner circumferential portion 21a of the catalyst case 21.

[0020] The inner wall 31 has a corrugated plate group 50 consisting of a plurality of corrugated plate portions 51, 52, 53, 54 formed in a corrugated shape. The inner wall 31 has a flat plate group 60 consisting of a plurality of flat plate portions 61, 62, 63, 64, 65 formed in a flat plate shape. The corrugated plate portions 51-54 and the flat plate portions 61-65 are arranged such that one of the corrugated plate portions 51-54 and one of the flat plate portions 61-65 overlaps alternately with their thickness directions aligned in a direction perpendicular to the flow direction.

[0021] 1, 2, and 5, the catalyst case 21 is disposed in an inclined position that rises upward from the front of the vehicle to the rear of the vehicle. As shown in Fig. 5 and Fig. 6, the upstream end 30b in the flow direction of the metal catalyst carrier 30 is formed in a step shape (hereinafter, referred to as a "first step shape" as necessary) that rises upward from the downstream to the upstream of the flow direction in a side view of the vehicle.

[0022] Furthermore, the exhaust device 10 for the motorcycle according to this embodiment can be generally configured as follows: As shown in Figures 1 to 3 and 5, the downstream end 22a of the pipe 22 in the flow direction is connected to the upper section 21c of the upstream end 21b of the catalyst case 21 in the flow direction.

[0023] As shown in Fig. 5, the lengths of the multiple passage sections 41a to 44a in the metal catalyst carrier 30 decrease from the top to the bottom. As shown in Fig. 4 and Fig. 6, the metal catalyst carrier 30 is formed in an inverted trapezoid shape so that its width decreases from the top to the bottom when viewed in the flow direction.

[0024] "Motorcycle Details" 1, a motorcycle having an exhaust system 10 according to this embodiment can be configured in detail as follows. A motorcycle body 1 has a front wheel 2 and a rear wheel 3 spaced apart from each other in the front-to-rear direction. The rear wheel 3 is located forward of the front wheel 2.

[0025] The vehicle body 1 has a transmission 4 located rearward of the engine 11. The transmission 4 is adjacent to the engine 11 in the front-rear direction. The transmission 4 and the engine 11 are located between the front wheels 2 and the rear wheels 3 in the front-rear direction. The vehicle body 1 has a fuel tank 5 located above the transmission 4 and the engine 11.

[0026] The vehicle body 1 has a seat 6 located rearward relative to a fuel tank 5. The vehicle body 1 also has a handlebar portion 7 located forward relative to the fuel tank 5. A rider can operate the handlebar portion 7 to control the motorcycle while seated on the seat 6.

[0027] "Details of the exhaust pipe of the exhaust system" 1 to 5, the exhaust pipe 20 of the exhaust device 10 according to this embodiment can be configured in detail as follows. As shown in Fig. 1, the exhaust pipe 20 of the exhaust device 10 has a muffler (silencer) 23 located at the downstream end in the flow direction of the exhaust pipe 20. The exhaust pipe 20 has an intermediate pipe 24 extending so as to communicate between the catalyst case 21 and the muffler 23.

[0028] Although not particularly clearly shown, the upstream pipe 22 is an exhaust manifold 22 having a plurality of header sections 22b (see FIG. 1) extending from the engine 11 and a collector section 22c (see FIG. 1) in which the plurality of header sections 22b are joined together at the downstream end 22a of the upstream pipe 22. As shown in FIG. 3, the downstream end 22a of the pipe 22 is connected to approximately the center in the width direction of the upper section 21c at the upstream end 21b of the catalyst case 21.

[0029] 1, the catalyst case 21 of the exhaust pipe 20 is disposed below the transmission 4 and the engine 11. The catalyst case 21 is disposed so as to overlap with the transmission 4 and the engine 11 when viewed in the up-down direction.

[0030] As shown in Fig. 5, in the exhaust pipe 20, the upstream end 21b of the catalyst case 21 is spaced apart from the upstream end 30b of the metal catalyst carrier 30 in the flow direction. When viewed from the side of the vehicle, the upstream end 21b of the catalyst case 21 is formed in a substantially linear shape that is inclined so as to rise upward from the downstream side in the flow direction toward the upstream side. The inclination of the upstream end 21b of the catalyst case 21 substantially matches the gradient of the upstream end 30b of the metal catalyst carrier 30. The downstream end 21d of the catalyst case 21 in the flow direction is spaced apart from the downstream end 30c of the metal catalyst carrier 30 in the flow direction.

[0031] However, the upstream end of the catalyst case can be formed in a step shape substantially similar to the first step shape of the upstream end of the metal catalyst support. The slope of the upstream end of the catalyst case can also be different from the slope of the upstream end of the metal catalyst support.

[0032] 2 and 5, the downstream end 21d of the catalyst case 21 is formed in a substantially linear shape extending in a direction substantially perpendicular to the flow direction in a side view of the vehicle. The downstream end 21d of the catalyst case 21 is substantially parallel to the downstream end 30c of the metal catalyst carrier 30 in a side view of the vehicle. However, the downstream end of the catalyst case may be inclined with respect to the downstream end of the metal catalyst carrier in a side view of the vehicle.

[0033] The top 21e and bottom 21f of the catalyst case 21 in the vertical direction are formed to correspond to the top 30d and bottom 30e of the metal catalyst carrier 30 in the vertical direction, respectively. The top 21e and bottom 21f of the catalyst case 21 are in close contact with the top 30d and bottom 30e of the metal catalyst carrier 30, respectively.

[0034] The top 21e and bottom 21f of the catalyst case 21 extend in a substantially linear shape so as to correspond to the inclined posture of the catalyst case 21. The top 21e and bottom 21f of the catalyst case 21 are substantially parallel to each other. However, the top and bottom of the catalyst case may be inclined to each other. At least one of the top and bottom of the catalyst case may be formed to include a curve.

[0035] 4, both side portions 21g, 21h in the width direction of the catalyst case 21 are formed to correspond to both side portions 30f, 30g in the width direction of the metal catalyst carrier 30. Both side portions 21g, 21h of the catalyst case 21 are in close contact with both side portions 30f, 30g of the metal catalyst carrier 30, respectively.

[0036] As shown in Figures 3 and 4, each of the widthwise side portions 21g, 21h of the catalyst case 21 is formed in a substantially linear shape that inclines toward substantially the center of the widthwise direction of the catalyst case 21 from top to bottom when viewed in the flow direction. The both side portions 21g, 21h of the catalyst case 21 are substantially symmetrical in the widthwise direction. However, the both side portions of the catalyst case may be inclined relative to each other. At least one of the both side portions of the catalyst case may be formed to include a curve.

[0037] 2 and 5, the upstream end 24a in the flow direction of the intermediate pipe 24 is attached, when viewed in the vehicle width direction, to approximately the center in a direction approximately perpendicular to the flow direction of the downstream end 21d of the catalyst case 21. Although not particularly clearly shown, the upstream end 24a of the intermediate pipe 24 is attached to approximately the center in the width direction of the downstream end 21d of the catalyst case 21.

[0038] 1, a downstream end 24b in the flow direction of the intermediate pipe 24 is connected to an upstream end 23a in the flow direction of the muffler 23. The muffler 23 has an exhaust outlet 23c located at the downstream end 23b in the flow direction.

[0039] The material used for each of the catalyst case 21, the upstream pipe 22, the muffler case 23d of the muffler 23, and the intermediate pipe 24 (hereinafter referred to as "cases" as necessary) of the exhaust pipe 20 is metal. For example, the metal used for each case may be a stainless steel alloy.

[0040] However, the material used for each of the cases is not limited thereto. The metal used for at least one of the cases can be a metal other than a stainless steel alloy. Such metal can be selected from iron, iron alloys, titanium, titanium alloys, aluminum, aluminum alloys, etc. The material used for at least one of the cases can be a material other than a metal. For example, such material can be selected from Kevlar, carbon, etc.

[0041] In such an exhaust pipe 20, gas exhausted from the engine 11 passes through the upstream pipe 22 and enters the catalyst case 21. The gas that enters the catalyst case 21 passes through the multiple passage sections 41a-44a in the metal catalyst carrier 30. After that, the gas that has passed through the multiple passage sections 41a-44a enters the intermediate pipe 24 from the catalyst case 21. Furthermore, the gas that has entered the intermediate pipe 24 passes through the intermediate pipe 24 and the muffler 23, and is then exhausted from the exhaust outlet 23c to the outside of the exhaust pipe 20, i.e., to the outside of the vehicle.

[0042] "Details of the metal catalyst carrier in the exhaust pipe" 4 to 6, the metal catalyst carrier 30 of the exhaust pipe 20 can be specifically configured as follows. The metal used for the inner wall 31 is a stainless steel alloy. The catalyst 32 of the metal catalyst carrier 30 can be platinum, palladium, rhodium, gold, silver, or a mixture of two or more of these metals.

[0043] The metal used for the inner wall 31 of the metal catalyst carrier 30 of the exhaust pipe 20 is a stainless steel alloy. However, the metal used for the inner wall may be other than the stainless steel alloy. For example, the metal used for the inner wall may be an Fe-Cr-Al alloy, a Ni-Cr-Al alloy, or the like.

[0044] 4 to 6 show, as an example, a case where the passing compartment group 40 of the metal catalyst carrier 30 is composed of four types of passing compartment rows 41, 42, 43, and 44, each set to four different lengths in the flow direction, that is, a first passing compartment row 41, a second passing compartment row 42, a third passing compartment row 43, and a fourth passing compartment row 44. In this case, the four types of passing compartment rows 41, 42, 43, and 44 are respectively arranged with four types of passing compartments 41a, 42a, 43a, and 44a corresponding to the lengths in the flow direction, that is, the first passing compartment 41a, the second passing compartment 42a, the third passing compartment 43a, and the fourth passing compartment 44a.

[0045] In other words, each of the passage sections 41-44 has a plurality of passage sections 41a-44a whose flow-direction length is set to correspond to the flow-direction length of the passage section row 41-44. The plurality of passage sections 41a-44a in each of the passage section rows 41-44 are aligned in the width direction. Each of the passage section rows 41-44 extends in a substantially linear shape so as to correspond to the inclined posture of the catalyst case 21. Each of the passage sections 41a-44a also extends in a substantially linear shape so as to correspond to the inclined posture of the catalyst case 21.

[0046] The first to fourth passing section rows 41 to 44 are arranged in this order from bottom to top. The first to fourth passing sections 41a to 44a are also arranged in this order from bottom to top. The lengths of the first to fourth passing section rows 41 to 44 in the flow direction are set to increase in order from bottom to top. Each of the passing sections 41a to 44a is formed in a substantially triangular or substantially inverted triangular shape when viewed in the flow direction.

[0047] However, the group of passage sections may be composed of a plurality of types of passage section arrays each having a plurality of different flow direction lengths, the flow direction lengths of the plurality of types of passage section arrays being set to increase in order from bottom to top.

[0048] Figures 4 to 6 show, as an example, a case in which the corrugated plate group 50 of the metal catalyst carrier 30 is composed of four corrugated plate sections 51, 52, 53, and 54, namely, a first corrugated plate section 51, a second corrugated plate section 52, a third corrugated plate section 53, and a fourth corrugated plate section 54, which correspond to the flow-direction lengths of the four types of passing section rows 41 to 44, respectively.

[0049] However, the corrugated plate group may be composed of a plurality of corrugated plate portions each corresponding to the flow direction lengths of the plurality of types of passing section rows, the flow direction lengths of the corrugated plate portions being set so as to increase in order from bottom to top.

[0050] 4 to 6 show, as an example, a case in which the flat plate group 60 of the metal catalyst carrier 30 is composed of four flat plate portions 61, 62, 63, and 64 corresponding to the flow direction lengths of the four types of passing compartment rows 41 to 44, i.e., a first flat plate portion 61, a second flat plate portion 62, a third flat plate portion 63, and a fourth flat plate portion 64, and an additional flat plate portion 65 corresponding to the flow direction length of the longest passing compartment row 44, i.e., the fourth passing compartment row 44, i.e., a fifth flat plate portion 65. The inner wall 31 also has a side plate portion 70 arranged along one side edge in the width direction.

[0051] However, the plate group may also be made up of a plurality of plate sections each corresponding to the length in the flow direction of a plurality of types of passage compartment rows, and an additional plate section corresponding to the longest passage compartment row in the flow direction, the plurality of plate sections being successively longer from bottom to top, and the additional plate section being located above the plurality of plate sections.

[0052] Each passing section 41a-44a is defined by the corresponding corrugated plate portion 51-54 and a flat plate portion 61-64 or an additional flat plate portion 65 located above or below the corrugated plate portion 51-54 and adjacent to it in the vertical direction, or by the corrugated plate portion 51-54 corresponding to the passing section 41a-44a and an adjacent flat plate portion 62-64 or an additional flat plate portion 65 located above the corrugated plate portion 51-54 and adjacent to it in the vertical direction, and a side plate portion 70.

[0053] In the inner wall 31, the upper end of the side plate portion 70 is connected to one end in the width direction of the additional flat plate portion 65. The other end in the width direction of the additional flat plate portion 65 is connected to the other end in the width direction of the uppermost corrugated plate portion 54. The other end in the width direction of each corrugated plate portion 51-54 is connected to the other end in the width direction of the flat plate portion 61-64 located below the corrugated plate portion 51-54 and adjacent thereto in the vertical direction, and one end in the width direction of each flat plate portion 61-64 is connected to one end in the width direction of the corrugated plate portion 51-53 located below the flat plate portion 61-64 and adjacent thereto in the vertical direction. The corrugated plate group 50, the flat plate group 60, and the side plate portion 70 of the inner wall 31 are formed from one cut and processed strip material 100.

[0054] "Outline of manufacturing method for exhaust device" 7 to 9, the manufacturing method of the exhaust device 10 according to this embodiment is roughly as follows: As shown in Fig. 7, the manufacturing method of the exhaust device 10 includes a manufacturing step S10 of the metal catalyst support 30 (metal catalyst support manufacturing step).

[0055] 8 and 9, the metal catalyst support manufacturing process S10 includes a process (material preparation process) S11 of preparing a band material 100, which is a material for the metal catalyst support 30. The band material 100 is made of the metal used for the above-mentioned inner wall 31. The band material 100 is also formed into a band shape.

[0056] The metal catalyst carrier manufacturing process S10 includes a process (material cutting process) S12 of cutting one edge 100a in the width direction of the strip material 100 to form a second step shape having a plurality of stages 101, 102, 103, 104 arranged in the longitudinal direction of the strip material 100 so as to form the upstream end 30b of the metal catalyst carrier 30 having the first step shape as described above. In addition, in Fig. 9, one side of the width direction of the strip material 100 is indicated by a one-sided arrow W1, and the other side of the width direction of the strip material 100 is indicated by a one-sided arrow W2. In addition, in Fig. 9, one side of the longitudinal direction of the strip material 100 is indicated by a one-sided arrow U1, and the other side of the longitudinal direction of the strip material 100 is indicated by a one-sided arrow U2.

[0057] The multiple stages 101-104 are shaped so that the length in the width direction of the strip material 100 decreases in sequence from one side to the other side in the longitudinal direction of the strip material 100. The strip material 100 cut in the material cutting process S12 has multiple stage regions 111, 112, 113, and 114 aligned in the longitudinal direction to correspond to the multiple stages 101, 102, 103, and 104, respectively.

[0058] The metal catalyst carrier manufacturing process S10 includes a step (material bending step) S13 of bending the plurality of stage regions 111-114 in the cut strip material 100 in sequence along the longitudinal direction so as to form one of the plurality of stage regions 111-114 as the corrugated plate portions 51-54 and the flat plate portions 61-64 which overlap each other, thereby obtaining the inner wall 31. Furthermore, the metal catalyst carrier manufacturing process S10 includes a step (catalyst coating step) S14 of coating the surface 31a of the inner wall 31 with the above-mentioned catalyst 32.

[0059] "Details of exhaust system manufacturing method" 7 to 9, the manufacturing method of the exhaust device 10 according to this embodiment can be described in detail as follows. As shown in Fig. 7, the manufacturing method of the exhaust device 10 includes, after the metal catalyst carrier manufacturing step S10, a step of preparing the upstream pipe 22 (upstream pipe preparation step) S20, a step of preparing the catalyst case 21 (catalyst case preparation step) S30, a step of preparing the intermediate pipe 24 (intermediate pipe preparation step) S40, and a step of preparing the muffler 23 (muffler preparation step) S50. Note that the metal catalyst carrier manufacturing step S10, the upstream pipe preparation step S20, the catalyst case preparation step 30, the intermediate pipe preparation step S40, and the muffler preparation step S50 can be performed in any order.

[0060] The manufacturing method of exhaust device 10 includes a step of assembling metal catalyst carrier 30, upstream pipe 22, catalyst case 21, intermediate pipe 24, and muffler 23 to obtain exhaust pipe 20 (exhaust pipe assembling step S60). The manufacturing method of exhaust device 10 also includes a step of attaching assembled exhaust pipe 20 to engine 11 (exhaust pipe attaching step S70).

[0061] 9 shows, as an example, a case where the strip material 100 cut in the material cutting step S12 has four stage regions 111-114 each set to a widthwise length corresponding to the flow direction length of the four passing section rows 41-44. That is, in FIG. 9, the cut strip material 100 has first to fourth stage regions 111-114 each set to a widthwise length corresponding to the flow direction length of the first to fourth passing section rows 41-44. However, the cut strip material may have multiple stage regions each corresponding to the flow direction length of multiple passing section rows.

[0062] In the cut and processed strip material 100, each stage region 111-114 has corrugated plate corresponding portions 121-124 and flat plate corresponding portions 131-134 for forming the corrugated plate portions 51-54 and flat plate portions 61-64 whose flow direction lengths correspond to the width direction lengths of the stage regions 111-114. In each stage region 111-114, the corrugated plate corresponding portions 121-124 are located on one side of the flat plate corresponding portions 131-134 in the flow direction of the strip material 100 and are adjacent to them in the flow direction.

[0063] The cut strip material 100 has an additional plate-like portion 135 located on one side of and adjacent to the widest stage region 114 in the longitudinal direction. The additional plate-like portion 135 is intended to form the additional plate portion 65.

[0064] The cut strip material 100 has a side plate corresponding portion 140 located on one side of the longitudinal direction relative to the additional flat plate corresponding portion 135 and adjacent thereto in the longitudinal direction. The side plate corresponding portion 140 is intended to form the side plate portion 70. One edge portion 140a in the width direction of the side plate corresponding portion 140 is formed into the first step shape described above. In FIG. 9, the boundaries between adjacent portions in the longitudinal direction of the strip material 100 among the corrugated plate corresponding portions 121-124, the flat plate corresponding portions 131-134, the additional flat plate corresponding portion 135, and the side plate corresponding portion 140 are indicated by imaginary lines.

[0065] In the material bending step S13, the cut strip material 100 is folded in a direction from one side to the other side of its length, in the order of the side plate corresponding portion 140, the additional flat plate corresponding portion 135, and the plurality of stage regions 111-114. When each stage region 111-114 is folded in the course of folding the entire cut strip material 100, the corrugated plate corresponding portions 121-124 are folded in a corrugated shape. However, the corrugated plate corresponding portions of each stage region can also be folded in a corrugated shape in advance, before folding the entire cut strip material.

[0066] As described above, the exhaust device 10 for a motorcycle according to this embodiment includes an engine 11 having an exhaust port 11a for discharging gas, and an exhaust pipe 20 connected to the exhaust port 11a so as to allow gas from the exhaust port 11a to pass therethrough, the exhaust pipe 20 including a metal catalyst carrier 30 arranged along the flow direction of gas passing through it, a catalyst case 21 that houses the metal catalyst carrier 30 and is arranged below the engine 11, and a pipe 22 extending to communicate between the exhaust port 11a of the engine 11 and the catalyst case 21, the metal catalyst carrier 30 having an inner wall 31 that defines a plurality of passage sections 41a to 44a extending along the flow direction, a catalyst 32 is coated on a surface 31a of the inner wall 31 facing the passage sections 41a to 44a, and the metal catalyst carrier 30 has an outer circumferential portion 30a that is in contact with the catalyst an exhaust device (10) for a motorcycle, the exhaust device (10) being fitted into the catalyst case (21) so as to abut against the inner periphery (21a) of the case (21); an inner wall (31) of the metal catalyst carrier (30) having a plurality of corrugated portions (51-54) formed in a corrugated shape and a plurality of flat portions (61-64) formed in a flat shape, the plurality of corrugated portions (51-54) and the plurality of flat portions (61-64) being arranged so that one of the plurality of corrugated portions (51-54) and one of the plurality of flat portions (61-64) are alternately stacked with their thickness directions aligned in a direction perpendicular to the flow direction; the catalyst case (21) being arranged in an inclined position rising upward from the front of the vehicle toward the rear of the vehicle; and an upstream end (30b) of the metal catalyst carrier (30) in the flow direction is formed in a stepped shape rising upward from the downstream to the upstream of the flow direction, as viewed from the side of the vehicle.

[0067] In such an exhaust device 10, even if the catalyst case 21 is arranged in an inclined position that rises from the front to the rear, the upstream end 21b of the catalyst case 21 can be formed to correspond to the upstream end 30b of the metal catalyst carrier 30 that is formed in a step shape that rises upward from the downstream to the upstream in the flow direction. Therefore, even if the catalyst case 21 containing the metal catalyst carrier 30 is moved toward the front in order to reduce the path of exhaust gas from the engine 11 to the metal catalyst carrier 30, a sufficient distance can be secured from the catalyst case 21, particularly the upstream end 21b of the catalyst case 21, to the ground G (shown in FIG. 1). As a result, the catalyst case 21 containing the metal catalyst carrier 30 can be efficiently prevented from contacting the ground G.

[0068] In such an exhaust device 10, the catalyst 32 of the metal catalyst carrier 30 can be warmed up early by the hot air from the engine 11 due to the reduction of the path of the exhaust gas from the engine 11 to the metal catalyst carrier 30, and the catalyst 32 can be activated by the warming. In addition, the upstream end 30b of the metal catalyst carrier 30 formed in a stepped shape allows the exhaust gas to flow into the metal catalyst carrier 30 in a turbulent state, so that the exhaust gas can be prevented from passing through the metal catalyst carrier 30 without sufficiently contacting the surface of the catalyst 32. In other words, the exhaust gas can be allowed to pass through the metal catalyst carrier 30 while being sufficiently in contact with the surface of the catalyst 32. As a result, the purification performance of the exhaust gas can be improved. Therefore, in the exhaust device 10 according to this embodiment, the purification performance of the exhaust gas can be improved, and the catalyst case 21 containing the metal catalyst carrier 30 can be efficiently prevented from contacting the ground G.

[0069] In the exhaust device 10 of this embodiment, the downstream end 22a in the flow direction of the pipe 22 is connected to the upper section 21c at the upstream end 21b in the flow direction of the catalyst case 21, and the lengths of the multiple passage sections 41a to 44a in the metal catalyst carrier 30 decrease from top to bottom.

[0070] In such an exhaust device 10, the exhaust gas that has passed through the pipe 22 flows into the catalyst case 21 from the upper section 21c of the upstream end 21b of the catalyst case 21. Therefore, the flow velocity of the exhaust gas flowing below the metal catalyst carrier 30 is slower than the flow path of the exhaust gas flowing above the metal catalyst carrier 30, while the length of the passage section below the metal catalyst carrier 30 is shorter than the length of the passage section above the metal catalyst carrier 30, so that the flow velocity of the exhaust gas flowing throughout the entire metal catalyst carrier 30 can be made uniform. As a result, the purification performance of the exhaust gas can be improved.

[0071] In the exhaust device 10 according to this embodiment, the metal catalyst carrier 30 is formed in an inverted trapezoid shape so that its width decreases from top to bottom as viewed in the flow direction. In such an exhaust device 10, the catalyst case 21 can be formed to correspond to the metal catalyst carrier 30 having an inverted trapezoid shape as viewed in the flow direction, so that the catalyst case 21 housing the metal catalyst carrier 30 can be efficiently prevented from contacting the ground G when the motorcycle makes a turn while banking.

[0072] The method for manufacturing an exhaust device 10 for a motorcycle according to the present embodiment includes the steps of: providing a metal catalyst carrier 30 for the exhaust device 10 for a motorcycle; the metal catalyst carrier 30 has an inner wall 31 that defines a plurality of passage sections 41a-44a extending along a gas flow direction; the inner wall 31 has a plurality of corrugated plate portions 51-54 formed in a corrugated shape and a plurality of flat plate portions 61-64 formed in a flat plate shape; and forming the corrugated plate portions 51-54 and the flat plate portions 61-64 in a state in which the thickness directions of the corrugated plate portions 51-54 and the flat plate portions 61-64 are aligned in a direction perpendicular to the gas flow direction. a step S10 of manufacturing a metal catalyst carrier 30, in which one of the flat plate portions 51 to 54 and one of the flat plate portions 61 to 64 are arranged so as to overlap each other alternately, and an upstream end portion 30b of the metal catalyst carrier 30 in the flow direction is formed into a first step shape that rises upward from the downstream side toward the upstream side in the flow direction in a side view, the step S10 of manufacturing the metal catalyst carrier 30 comprising: a step S11 of preparing a metal band material 100 that is a material of the metal catalyst carrier 30 and is formed into a band shape; a step of cutting one edge 100a in the width direction of the strip material 100 into a second step shape having a plurality of stages 101-104 arranged in the longitudinal direction of the strip material 100 so as to form the upstream end 30b of the first step shape, the plurality of stages 101-104 being shaped so as to successively decrease the length in the width direction of the strip material 100 from one side to the other side in the longitudinal direction of the strip material 100, and the cut strip material 100 is cut by the plurality of stages 101-104. 04, respectively; a step S13 of bending the plurality of stage regions 111-114 in the cut and processed strip material 100 sequentially along the longitudinal direction so as to form one of the plurality of stage regions 111-114 as the corrugated plate portions 51-54 and the flat plate portions 61-64 overlapping each other, thereby obtaining the inner wall 31; and a step S14 of coating a surface 31a of the inner wall 31 with a catalyst 32.

[0073] In the exhaust device 10 manufactured by such a manufacturing method, the same effects as those of the exhaust device 10 described above can be obtained. In addition, in the manufacturing method of the exhaust device 10 according to this embodiment, the metal catalyst carrier 30 can be manufactured by a simple operation of folding back one cut strip material 100, so that the manufacturing of the metal catalyst carrier 30 can be facilitated. Therefore, in the manufacturing method according to this embodiment, the purification performance of the exhaust gas can be improved, and the catalyst case 21 containing the metal catalyst carrier 30 can be efficiently prevented from contacting the ground G, and the manufacturing of the metal catalyst carrier 30 can be facilitated.

[0074] Although the embodiment of the present invention has been described above, the present invention is not limited to the above-mentioned embodiment, and the present invention can be modified and changed based on the technical concept thereof. [Explanation of symbols]

[0075] 10...Exhaust system 11...engine, 11a...exhaust port 20…Exhaust pipe 21... catalyst case, 21a... inner periphery, 21b... upstream end, 21c... upper section 22... Pipe, upstream pipe, exhaust manifold, 22a... downstream end 30...metal catalyst carrier, 30a...outer periphery, 30b...upstream end, 31...inner wall, 31a...surface, 32...catalyst 41a...passing section, first passing section, 42a...passing section, second passing section, 43a...passing section, third passing section, 44a...passing section, fourth passing section 51... corrugated plate portion, first corrugated plate portion, 52... corrugated plate portion, second corrugated plate portion, 53... corrugated plate portion, third corrugated plate portion, 54... corrugated plate portion, fourth corrugated plate portion 61... Flat plate part, first flat plate part, 62... Flat plate part, second flat plate part, 63... Flat plate part, third flat plate part 64...Flat plate part, 4th flat plate part 100...band material, 100a...one edge 101, 102, 103, 104...Stage 111... stage area, first stage area, 112... stage area, second stage area, 113... stage area, third stage area, 114... stage area, fourth stage area S10...Manufacturing process, metal catalyst carrier manufacturing process, S11...process, material preparation process, S12...process, material cutting process, S13...process, material bending process, S14...process, catalyst coating process

Claims

1. an engine having an exhaust port for discharging gas; an exhaust pipe connected to the exhaust port so as to allow gas from the exhaust port to pass therethrough; Equipped with the exhaust pipe includes a metal catalyst carrier arranged along the flow direction of gas passing through the exhaust pipe, a catalyst case that houses the metal catalyst carrier and is arranged below the engine, and a pipe that extends to communicate an exhaust port of the engine and the catalyst case, The metal catalyst support has an inner wall that defines a plurality of passage sections extending along the flow direction, a catalyst is coated on the surface of the inner wall facing the passage section; an exhaust system for a motorcycle, the metal catalyst carrier being fitted into the catalyst case such that an outer periphery of the metal catalyst carrier abuts against an inner periphery of the catalyst case, The inner wall of the metal catalyst carrier has a plurality of corrugated plate portions formed in a corrugated shape and a plurality of flat plate portions formed in a flat plate shape, The plurality of corrugated plate portions and the plurality of flat plate portions are arranged such that one of the plurality of corrugated plate portions and one of the plurality of flat plate portions are alternately stacked with their thickness directions aligned in a direction perpendicular to the flow direction, The catalyst case is disposed in an inclined position rising upward from the front of the vehicle toward the rear of the vehicle, The exhaust device for a motorcycle, wherein the metal catalyst carrier is formed in an inverted trapezoid shape such that its width decreases from top to bottom when viewed in the flow direction.

2. A downstream end of the pipe in the flow direction is connected to an upper section at an upstream end of the catalyst case in the flow direction, 2. The exhaust system for a motorcycle according to claim 1, wherein lengths of the plurality of passage sections in the metal catalyst carrier decrease from top to bottom.

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