JP4668231B2 - Engine exhaust system - Google Patents

Description

  The present invention relates to an engine exhaust device in which an exhaust passage extending from an exhaust port of an engine to an exhaust muffler is constituted by an exhaust passage peripheral wall member.

As an exhaust passage peripheral wall member for constituting an exhaust passage of an engine, a pipe-shaped exhaust pipe having no joint portion in the circumferential direction is mainly used. However, a portion where a plurality of exhaust passages gather, a plurality of exhaust passages For example, a structure in which a pair of halved exhaust passage peripheral wall members are joined together by welding, that is, a so-called “monaka structure” is employed in a part that divides into two parts or a part in which the exhaust passage is bent. There are many cases. As prior art documents, there are Patent Documents 1 and 2, and the like.
Japanese Utility Model Publication No. 63-130618 JP-A-8-210131

  The exhaust passage peripheral wall member is heated by circulating high-temperature exhaust gas while the engine is running, and is cooled while the engine is stopped. In the exhaust passage peripheral wall member, cracks are likely to occur in the joint due to the thermal stress. In particular, high temperature exhaust gas does not flow smoothly at the gathering portion, branching portion, or bent portion of the exhaust passage, and collides with the exhaust passage peripheral wall member, so that the degree of thermal expansion increases and a large thermal stress is applied. Many.

  Further, during the operation of the engine, the exhaust device is vibrated as a whole. Particularly, in an engine mounted on a vehicle such as a motorcycle, the entire exhaust passage vibrates greatly, and the collective portion, branching portion or bent portion of the exhaust passage In this case, bending stress or the like due to vibration is likely to concentrate, and this bending stress may cause a crack in the joint.

  In addition, in the said patent document 1, although the reinforcement board adheres to the outer peripheral surface of the branch part (crotch part) of an exhaust manifold by welding, and the structure which suppresses the crack of a junction part is disclosed in this way, In the structure in which the reinforcing plate is fixed, the effect of improving the strength of the joint can be expected, but the hot exhaust gas directly collides with the inner peripheral surface of the exhaust passage peripheral wall member including the joint, and the joint of the exhaust passage peripheral wall member It is not possible to reduce the thermal stress applied to.

  An object of the present invention is to provide an engine exhaust apparatus that can suppress thermal stress caused by exhaust gas and vibration stress due to vibrations applied to a joint portion of an exhaust passage peripheral wall member, and can effectively prevent cracks in the joint portion. is there.

In order to solve the above-mentioned problem, the invention according to claim 1 is an engine exhaust system in which an exhaust passage extending from an exhaust port of the engine to an exhaust muffler is constituted by an exhaust passage peripheral wall member.
At least a part of the exhaust passage peripheral wall member has a joint portion formed by joining end portions in the circumferential direction of the exhaust passage peripheral wall member by welding, and the joining of the inner peripheral surface of the exhaust passage peripheral wall member The reinforcing member is fixed to a predetermined region including the portion by fixing means.

  According to the above configuration, the reinforcing member prevents high-temperature exhaust gas from contacting or colliding with the joint portion, thereby suppressing the generation of thermal stress in the joint portion, and also reinforcing the joint portion physically. Therefore, the bending stress due to the vibration of the exhaust device can be prevented from concentrating on the joint. By these, generation | occurrence | production of the crack in a junction part can be suppressed.

  In addition, since the reinforcing member is arranged on the inner peripheral surface of the exhaust passage peripheral wall member, it is possible to maintain the compactness of the exhaust device and to maintain a good external appearance, and to arrange it close to the exhaust device during assembly. There is no need to consider interference with other parts.

  According to a second aspect of the present invention, in the exhaust system for an engine according to the first aspect, in the joint portion, circumferential ends of a pair of halved exhaust passage peripheral wall members are joined.

  According to the said structure, manufacture of the exhaust passage surrounding wall member in the site | part which has a complicated shape becomes easy.

  According to a third aspect of the present invention, in the engine exhaust system according to the first or second aspect, flanges formed on the exhaust passage peripheral wall member are joined to each other at the joint portion.

  According to the said structure, manufacture of the exhaust passage surrounding wall member in the site | part which has a complicated shape becomes still easier.

  According to a fourth aspect of the present invention, in the exhaust system for an engine according to any one of the first to third aspects, the predetermined region to which the reinforcing member is fixed is the peripheral wall of the exhaust passage at a bent portion or a branched portion of the exhaust passage. It is the area | region of the internal peripheral surface of a member.

  According to the above configuration, the reinforcing member is fixed to the joint portion where the bending effect due to the thermal effect of the high-temperature exhaust gas and the vibration of the exhaust device is likely to occur. Occurrence can be suppressed.

  According to a fifth aspect of the present invention, in the engine exhaust system according to the fourth aspect, the predetermined region to which the reinforcing member is fixed is, of the inner peripheral surface of the exhaust passage peripheral wall member in the bent portion or the branched portion. This is a region substantially facing the exhaust gas flow in the exhaust passage.

  According to the above configuration, the reinforcing member is fixed to the joint portion that is most susceptible to the thermal influence of the high-temperature exhaust gas, so that the occurrence of cracks in the joint portion can be more efficiently suppressed.

  According to a sixth aspect of the present invention, in the engine exhaust device according to any one of the first to fifth aspects, the predetermined region is located on the exhaust downstream side of the catalyst device disposed in the exhaust passage.

  In the catalyst device, due to the reaction heat between the exhaust gas and the catalyst, the exhaust gas becomes a higher temperature and flows downstream, but by attaching a reinforcing member to the joint portion on the downstream side of such a catalyst device, The thermal influence on the joint can be effectively suppressed.

  According to a seventh aspect of the present invention, in the engine exhaust system according to any one of the first to sixth aspects, the fixing means is provided for one partition portion of the predetermined region partitioned by the joint portion. Is fillet weld, and the other compartment is plug weld.

  According to the above configuration, the joining work between the end portions of the exhaust passage peripheral wall member is facilitated, and, for example, in a structure in which one exhaust passage peripheral wall member is coupled by a pair of halved members in a so-called “monkey structure”. Before joining both halved members, the reinforcing member is fixed to the inner peripheral surface of one halved member by fillet welding from the inside, and after joining both halved members, the reinforcing member is joined to the other half It can be fixed to the member by plug welding from the outside, and the fixing work of the reinforcing member is facilitated. Further, by using fillet welding, it is possible to maintain a clean appearance of the exhaust device.

  In short, according to the present invention, the reinforcing member is fixed to a predetermined region of the inner peripheral surface of the exhaust passage peripheral wall member including the welded joint portion by fixing means such as welding. It is possible to suppress thermal deformation, prevent the occurrence of cracks in the joint, and improve the strength of the joint with respect to bending action and the like.

[First embodiment of the present invention]
1 to 13 show a first embodiment of the present invention, which is an exhaust system for an engine mounted on a motorcycle, and the first embodiment will be described based on these drawings.

(Overview of the entire motorcycle)
FIG. 1 is a right side view (a right side view seen from a rider) of a motorcycle equipped with an exhaust device according to the present invention. In FIG. 1, the body frame includes a pair of left and right main frames 2 and the main frame. A pair of left and right swing arm brackets 3 formed at the rear lower end of the frame 2 and a rear frame 4 etc. extending rearward and upward from the swing arm bracket 3 are provided. A seat 8 and the like are provided, and a multi-cylinder engine 10 is mounted in a lower space of the main frame 2. A front fork 12 is supported on the head pipe 11 formed at the front end of the main frame 2, a handle 13 is provided at the upper end of the front fork 12, and a front wheel 14 is supported at the lower end of the front fork 12. ing. A front end portion of the swing arm 16 is rotatably supported on the pivot portion 3 a of the swing arm bracket 3, and a rear wheel 17 is supported on the rear end portion of the swing arm 16.

  The multi-cylinder engine 10 is, for example, a parallel four-cylinder four-cycle engine in which four cylinders are arranged in the vehicle width direction, and an exhaust port 18a for each cylinder is opened on the front end surface of the cylinder head 18, and each exhaust port Four cylinder-specific exhaust pipes 20 are connected to 18a.

(Overall configuration of exhaust system)
The exhaust passage of the exhaust device is composed of a plurality of exhaust passage peripheral wall members, and the exhaust passage peripheral wall members are arranged in order from the exhaust upstream side to the four cylinder-specific exhaust pipes 20 and the lower side of the engine 10. A pair of upper and lower first exhaust collecting pipes 23 which are arranged and configured in a bifurcated shape, a second exhaust collecting pipe 24 connected to the rear end of the first exhaust collecting pipe 23, and the second An expansion pipe 25 formed at the rear end of the exhaust pipe 24, a pair of left and right branch exhaust pipes 26 formed at the rear end of the expansion pipe 25, and the left and right sides of the rear wheel 17 from each branch exhaust pipe 26. And a pair of left and right exhaust mufflers 21 disposed on the left and right sides of the rear wheel 17. The exhaust passages of the four cylinder-specific exhaust pipes 20 are gathered into two upper and lower exhaust passages in the first exhaust collecting pipe 23, and from two to one exhaust passage in the second exhaust collecting pipe 24. They are assembled, branched into the left and right branch exhaust pipes 26 in the latter half of the expansion pipe 25, and reach the left and right exhaust mufflers 21 via the left and right rear exhaust pipes 27. Each exhaust passage peripheral wall member will be described in detail below.

(Exhaust pipe by cylinder)
2 is an enlarged plan view of the exhaust device, and FIG. 3 is a left side view of the exhaust device. In FIG. 2, in order to distinguish the four cylinder-specific exhaust pipes 20 from each other, the first cylinder-specific exhaust pipe 20-1, the second cylinder-specific exhaust pipe 20-2, The cylinder-specific exhaust pipe 20-3 and the fourth cylinder-specific exhaust pipe 20-4 are referred to. Each cylinder-specific exhaust pipe 20-1, 20-2, 20-3, 20-4 is made of a stainless steel pipe member, extends downward on the front side of the engine 10, and is near the front lower end of the engine 10. 3 are gathered together at the center of the left and right widths, curved backward as shown in FIG. 3, and connected to the front end inlets of the upper and lower first exhaust collecting pipes 23, 23.

(First exhaust collecting pipe)
4 is an enlarged sectional view of the front end portion of the first exhaust collecting pipe 23 (IV-IV sectional enlarged view of FIG. 3). FIG. 5 is an enlarged sectional view of the rear end portion of the first exhaust collecting pipe 23 (FIG. 3 is a VV cross-sectional enlarged view). In FIG. 4, the front end portions of the upper and lower first exhaust collecting pipes 23 are formed in a peanut shape in which the central part of the left and right widths is constricted, and the upper first exhaust collecting pipe 23 includes a first cylinder. The lower end portion of the separate exhaust pipe 20-1 and the lower end portion of the fourth exhaust pipe 20-4 for each cylinder are connected, and the second exhaust pipe 20- for each cylinder is connected to the lower first exhaust collecting pipe 23. 2 is connected to the lower end of the third cylinder specific exhaust pipe 20-3.

  In FIG. 5, the rear end portions of the upper and lower first exhaust collecting pipes 23 are each formed in a half-cylindrical shape, and are joined so as to have a substantially circular cross section as a whole, and are formed in the center in the vertical direction. The upper exhaust passage 31 and the lower exhaust passage 32 are partitioned by a substantially horizontal partition wall 33. The upper exhaust passage 31 is an exhaust passage communicating with the first and fourth cylinder exhaust pipes 20-1 and 20-4 in FIG. 4, and the lower exhaust passage 32 in FIG. 5 is the second and second exhaust passages in FIG. This is an exhaust passage communicating with the exhaust pipes 20-2 and 20-3 for each of the three cylinders.

(Second exhaust collecting pipe 24, expansion pipe 25 and branch pipe 26)
6 is a plan view of the second exhaust collecting pipe 24, the expansion pipe 25, and the branch exhaust pipe 26. FIG. 7 is a perspective view of the second exhaust collecting pipe 24, the expansion pipe 25, and the branch exhaust pipe 26 as viewed from the rear left side. 8 is a sectional view taken along the line VIII-VIII in FIG. 6, FIG. 9 is a sectional view taken along the line IX-IX in FIG. 6, and FIG. 10 is a sectional view taken along the line XX in FIG. In FIG. 6, the second exhaust collecting pipe 24, the expansion pipe 25, and the branch exhaust pipe 26 are formed as a substantially Y-shaped integral 34 in plan view, and this Y-shaped integral 34 is As shown in FIG. 7, a substantially Y-shaped upper half member 34a in plan view and a Y-shaped lower half member 34b in plan view that matches the upper half member 34a from below are welded together. The two halved members 34a and 34b are made of a stainless steel plate, but may be made of a steel plate or a titanium alloy.

  In FIG. 7, the joint 35 includes an outward flange 35 a formed at the circumferential edge of the upper half member 34 a, as clearly shown at the right end of the right branch exhaust pipe 26 in FIG. 7, An outward flange 35b formed on the circumferential edge of the lower half member 34b so as to correspond to the flange 35a is joined by welding W0. Although only a part of the weld W0 is shown in FIG. 7, with respect to the entire Y-shaped integral 34, a joint 35 for joining the left side of the Y-shaped integral 34 and the right side of the Y-shaped integral 34 are shown. And a joining portion 35 that joins the rear portion of the Y-shaped integrated body 34.

  In FIG. 6, the left joint 35 of the Y-shaped integral 34 extends from the front left end of the second exhaust collecting pipe 24 to the left end of the second collecting pipe 24, the left end of the expansion pipe 25, and the left branch. The left branch exhaust pipe 26 reaches the left front end through the front end of the exhaust pipe 26. The right joint 35 of the Y-shaped integral 34 extends from the front right end of the second exhaust collecting pipe 24 to the right end of the second collecting pipe 24, the right end of the expansion pipe 25, and the right branch exhaust pipe 26. It passes through the front end and reaches the right rear end of the right branch exhaust pipe 26. The rear joint portion 35 of the Y-shaped integrated body 34 extends from the left rear end of the left branch exhaust pipe 26 to the rear end of the left branch exhaust pipe 26, the rear end portion 25a of the expansion pipe 25, and the right branch exhaust pipe. 26 passes through the rear end of the right branch exhaust pipe 26 and reaches the left rear end of the right branch exhaust pipe 26.

  In FIG. 8, the second exhaust collecting pipe 24 is formed in a cylindrical shape, and the front end portion of the second exhaust collecting pipe 24 is divided into an upper exhaust passage 38 and a lower exhaust passage 39 by a substantially horizontal partition wall 37. The upper exhaust passage 38 is partitioned, and a sensor attachment boss portion 40 is provided, and an oxygen sensor (exhaust gas sensor or air-fuel ratio sensor) 43 is attached to the sensor attachment boss portion 40. The partition wall 37 is formed with a communication hole 37a that communicates the upper and lower exhaust passages 38 and 39.

  In FIG. 9, a cylindrical honeycomb catalyst 41 is accommodated in the exhaust passage at the rear end portion of the second exhaust collecting pipe 24.

  In FIG. 10, the expansion pipe 25 is formed integrally with the second exhaust collecting pipe 24 at the rear end of the second exhaust collecting pipe 24 as described above, and the shape thereof is substantially the same as the first half cut off. It is formed in a hemispherical shape. The diameter of the front end of the expansion pipe 25 is larger than the diameter of the rear end of the second exhaust collecting pipe 24, so that the exhaust flow cross-sectional area is from the rear end of the second exhaust collecting pipe 24 to the expansion pipe 25. It expands temporarily at the time of moving to the front end, and is gradually reduced in the expansion tube 25 along the hemispherical inner surface of the expansion tube 25.

  Thus, the shape of the expansion tube 25 is a substantially hemispherical shape with the front half cut off, so that the size of the expansion tube 25 in the front-rear direction is made compact.

  In FIG. 6, in the present embodiment, the left branch exhaust pipe 26 extends leftward from the rear end of the expansion pipe 25 and opens leftward, while the right branch exhaust pipe 26 is curved to the right rear. Extends and opens backwards.

(Reinforcing structure of expansion pipe 25 and branch exhaust pipe 26)
11 is a cross-sectional view taken along the line XI-XI of FIG. 6, FIG. 12 is an enlarged view of the rear end of FIG. 10, and FIG. In FIG. 7, from the inner peripheral surface of the rear end portion 25a of the expansion pipe 25 to the inner peripheral surface of the left and right branch exhaust pipes 26, a predetermined region including the joint portion 35 is made of stainless steel as a reinforcing member. The reinforcing plate 50 is fixed by welding W1 and W2.

  The reinforcing plate 50 is formed in a three-dimensional shape that matches the inner peripheral surface shape of the expansion pipe 25 and the branch exhaust pipe 26, and corresponds to the expansion pipe 25 of the upper half member 34a as shown in FIG. The upper end of the reinforcing plate 50 is fixed to the portion by fillet welding W1. On the other hand, a portion corresponding to the expansion pipe 25 of the lower half member 34b is fixed by plug welding W2 using a long hole 52 formed in the lower half member 34b.

  In FIG. 7, the fillet weld W1 at the upper end of the reinforcing plate 50 is applied over the entire width of the left and right width of the reinforcing plate 50 or partially, while the plug weld W2 in the lower half of the reinforcing plate 50 is The left and right branch exhaust pipes 26 are provided in a streak shape in a separated state. In the present embodiment, the left and right ends of the reinforcing plate 50 are not welded.

  The thickness (thickness) of the reinforcing plate 50 is substantially the same as the thickness (thickness) of the expansion tube 25, for example, about 1 mm to 2 mm. The vertical width of the reinforcing plate 50 is, for example, about 20 mm to 40 mm. Preferably, it is set to about 30 mm.

(Assembly of Y-shaped integrated body 34 and reinforcing plate 50)
In FIG. 13, when assembling the Y-shaped integrated body 34, before joining the upper and lower half members 34a, 34b, the upper end of the reinforcing plate 50 is connected to the upper half member from the inside by the fillet weld W1. 34a is fixed to the inner peripheral surface of the rear end portion. At this time, the lower half of the reinforcing plate 50 protrudes below the lower end flange 35a of the upper half member 34a.

  Next, both the half members 34a and 34b are overlapped with each other, the flanges 35a and 35b are joined to each other by welding W0 (see FIG. 12), and then the elongated hole 52 of the lower half member 34b is used. The lower half of the reinforcing plate 50 is fixed to the inner peripheral surface of the lower half member 34b (expansion pipe 25) by plug welding W2 from the outside (see FIG. 12).

  In FIG. 2, the catalyst 41 disposed in the second exhaust collecting pipe 24 is inserted into the second exhaust collecting pipe 24 when, for example, the Y-shaped integral 34 is assembled or after assembly. Using the elongated hole 55 formed at the rear end portion of the second exhaust collecting pipe 24, the second exhaust collecting pipe 24 is fixed to the second exhaust collecting pipe 24 by plug welding from the outside.

(Exhaust gas flow)
The exhaust gas discharged from the exhaust ports 18a (FIG. 3) of the engine 10 of FIG. 2 into the exhaust passages 20-1, 20-2, 20-3, 20-4 for each cylinder is shown in FIG. As shown in FIG. 5, the first exhaust collecting pipe 23 collects the upper and lower exhaust passages 31 and 32. That is, in FIG. 5, the exhaust gases from the first and fourth cylinders are collected in the upper exhaust passage 31, and the exhaust gases from the second and third cylinders are gathered in the lower exhaust passage 32, respectively. It flows into the upper exhaust passage 38 and the lower exhaust passage 39 in the second exhaust collecting pipe 24 shown.

  In the second exhaust collecting pipe 24, the upper and lower exhaust passages 38 and 39 in FIG. 8 pass through the passage containing the honeycomb type catalyst 41 shown in FIG. And flows into the substantially hemispherical expansion tube 25 shown in FIG.

  The exhaust gas flowing into the expansion pipe 25 temporarily expands, and the exhaust gas flowing in the radially outer portion of the exhaust passage flows backward along the arcuate inner peripheral surface, and the reinforcing plate 50 However, the exhaust gas that passes through the vicinity of the central portion of the exhaust passage directly collides with the reinforcing plate 50 from substantially the front and branches to the left and right.

  In the flow of the exhaust gas in the expansion pipe 25, the inner peripheral surface of the rear end portion 25a of the expansion pipe 25 and the inner peripheral surface of the branch exhaust pipe 26 in the vicinity of the rear end portion 25a in FIG. Although it is an area | region which substantially opposes the flow of the exhaust gas which flows through the inside of the pipe | tube 24 and the substantially axial core part of the expansion pipe 25, by arrange | positioning the reinforcement board 50 in this area | region, exhaust gas is direct to the said area | region. Since the contact or collision is prevented and the thermal deformation of the region due to the high-temperature exhaust gas is suppressed, it is possible to prevent the joint 35 in the region from being cracked due to the thermal deformation. In particular, the expansion tube 25 is formed in a substantially hemispherical shape, and the inner peripheral surface of the rear end portion 25a of the expansion tube 25 is also partially spherical. Therefore, if the reinforcing plate 50 is not disposed. Although the exhaust gas collides strongly, the region is shielded from the exhaust gas by the reinforcing plate 50 as in the present embodiment, so that cracking of the joint 35 due to thermal deformation can be efficiently prevented. It is.

  Further, during operation, the entire exhaust device vibrates, and in particular, bending stress concentrates near the boundary between the expansion pipe 25 and the branch exhaust pipe 26 due to the vibration of the rear exhaust pipe 27. Since the vicinity of the boundary between the expansion pipe 25 and the branch exhaust pipe 26 is physically reinforced, it is possible to prevent the joint 35 from being cracked due to stress concentration.

  Further, in the present embodiment, as the reinforcing plate 50, the same stainless steel plate as the expansion tube 25 (Y-shaped integrated body 34) is used, and the reinforcing plate 50 having the same thickness as the expansion tube 25 is fixed. Therefore, distortion due to the difference in thermal expansion between the reinforcing plate 50 and the expansion pipe 25 does not occur.

[Second Embodiment]
FIG. 14 shows a second embodiment of the present invention. In FIG. 14, the joint portion 35 of the Y-shaped integral body 34 in which the expansion tube 25 is integrally formed has a joint structure of a wax type. That is, the joining portion 35 forms an outer fitting portion 55a at the peripheral end portion of the upper half member 34a, and the outer fitting portion 55a is connected to the outer side surface of the circumferential end portion 55b of the lower half member 34b. And is joined by welding W3. A reinforcing plate 50 is fixed to a predetermined region on the inner peripheral surface of the expansion pipe 25 including the joint portion 35 by welding W1 and W2. The structure other than the joint 35 is the same as that of the first embodiment, and the same parts and components are denoted by the same reference numerals (numbers).
[Third Embodiment]
FIG. 15 shows a third embodiment of the present invention. In FIG. 15, the joint portion 35 of the Y-shaped integral body 34 in which the expansion tube 25 is integrally formed has a joint structure by butting. That is, the peripheral end portion of the upper half member 34 a and the peripheral end portion of the lower half member 34 b are abutted and joined by welding W 4, and a predetermined region on the inner peripheral surface of the expansion pipe 25 including the joint portion 35. Further, the reinforcing plate 50 is fixed by welding W1 and W2. The structure other than the joint 35 is the same as that of the first embodiment, and the same parts and components are denoted by the same reference numerals (numbers).
[Fourth Embodiment]
FIG. 16 shows a fourth embodiment of the present invention. In the first to third embodiments, the exhaust passage peripheral wall member constituting the exhaust passage employs a structure in which a pair of upper and lower half members are joined by a joining portion. However, the fourth embodiment Then, as shown in FIG. 16, a plate is wound into a cylindrical shape, and flanges 60a and 60b are formed at the circumferential end of the exhaust passage peripheral wall member 60 made of one plate, and both flanges 60a and 60b are welded by W5. It has a joined structure. The reinforcing plate 50 is fixed to a predetermined region of the inner peripheral surface of the exhaust passage peripheral wall member 60 including the joint portion 35 by welding W1 and W2. The structure of the fourth embodiment is suitable for a bent portion of an exhaust passage, for example.

[Other embodiments]
(1) In the above-described embodiment, the reinforcing plate 50 made of a plate-like member is used as the reinforcing member, but various shapes of reinforcing members such as a block-like member and a rod-like member can also be used.

(2) In each of the above embodiments, fillet welding and plug welding are combined as means for fixing the reinforcing member such as the reinforcing plate 50, but the reinforcing plate is temporarily fixed to the inner peripheral surface of the expansion pipe 25. In this case, the upper and lower ends of the reinforcing plate 50 can be welded only by plug welding, and the reinforcing plate 50 can be fixed using spot welding. Further, as a fixing means for the reinforcing plate 50, it is possible to use a fixing means by brazing or caulking in addition to welding.

(3) As a region where the reinforcing member such as the reinforcing plate 50 is arranged, as in the first to third embodiments, the branch portion of the exhaust passage or the exhaust passage as in the fourth embodiment is used. In addition to the bent portion, a region including a joint portion such as the first exhaust collecting pipe 23 of FIG. 2 is also included.

(4) The present invention is not limited to the structure of the above embodiment, and can be added, changed or deleted without departing from the spirit of the invention.

Industrial application fields

  The present invention is not limited to the exhaust system of an engine mounted on a motorcycle, but is an engine mounted on various vehicles such as a four-wheel vehicle for rough terrain, an automobile, a water planing boat, or other industrial engines. It can also be applied to an exhaust device.

1 is a right side view of a motorcycle including an exhaust device for an engine according to a first embodiment of the present invention. FIG. 2 is an enlarged plan view of the exhaust device of FIG. 1. It is a left view of the exhaust apparatus of FIG. FIG. 4 is an enlarged sectional view taken along the line IV-IV in FIG. 3. FIG. 5 is an enlarged VV cross-sectional view of FIG. 3. FIG. 3 is a plan view of a Y-shaped integral body including a second exhaust collecting pipe, an expansion pipe, and a branch exhaust pipe of the exhaust device of FIG. 2. It is a perspective view of the same Y-shaped integrated object as FIG. It is a VIII-VIII cross-sectional enlarged view of FIG. It is the IX-IX cross-sectional enlarged view of FIG. FIG. 7 is an enlarged cross-sectional view taken along line XX in FIG. It is XI-XI sectional drawing of FIG. It is an enlarged view of the arrow XII part of FIG. It is a longitudinal cross-sectional view which shows the state in the middle of the assembly of a Y-shaped integrated object. It is an enlarged view of the same part as FIG. 12 of the exhaust apparatus by the 2nd Embodiment of this invention. It is an enlarged view of the same part as FIG. 12 of the exhaust apparatus by the 3rd Embodiment of this invention. It is an expansion longitudinal cross-sectional view of the reinforcement board arrangement | positioning part of the exhaust apparatus by the 4th Embodiment of this invention.

Explanation of symbols

10 Engine 18a Exhaust port 20 Cylinder exhaust pipe (an example of exhaust passage peripheral wall member)
23 1st exhaust collecting pipe (an example of exhaust passage peripheral wall member)
24 2nd exhaust collecting pipe (an example of exhaust passage peripheral wall member)
25 Expansion pipe (example of exhaust passage peripheral wall member)
26 Branch exhaust pipe (example of exhaust passage peripheral wall member)
34 Y-shaped integrated object (an example of an exhaust passage peripheral wall member)
34a Upper half member 34b Lower half member 35 Joint 35a, 35b Flange 60 Example of exhaust passage peripheral wall member 60a, 60b Flange W1, W2, W3, W4, W5 Welding

Claims (7)

In an engine exhaust device in which an exhaust passage from an exhaust port of an engine to an exhaust muffler is configured by an exhaust passage peripheral wall member,
At least a part of the exhaust passage peripheral wall member has a joint portion formed by joining the end portions in the circumferential direction of the exhaust passage peripheral wall member by welding,
An exhaust system for an engine, wherein a reinforcing member is fixed to a predetermined region including the joint portion on the inner peripheral surface of the exhaust passage peripheral wall member by fixing means. The engine exhaust device according to claim 1,
An exhaust system for an engine, characterized in that at the joint portion, end portions in the circumferential direction of a pair of halved exhaust passage peripheral wall members are joined together. The exhaust system for an engine according to claim 1 or 2,
An exhaust system for an engine, wherein flanges formed on the exhaust passage peripheral wall member are joined to each other at the joint. The engine exhaust device according to any one of claims 1 to 3,
The engine exhaust device according to claim 1, wherein the predetermined region to which the reinforcing plate is fixed is a region of an inner peripheral surface of the exhaust passage peripheral wall member in a bent portion or a branched portion of the exhaust passage. The exhaust system for an engine according to claim 4,
The predetermined region to which the reinforcing member is fixed is a region of the inner peripheral surface of the exhaust passage peripheral wall member at the bent portion or the branch portion that is substantially opposed to the exhaust gas flow in the exhaust passage. The engine exhaust system. The exhaust system for an engine according to any one of claims 1 to 5,
An exhaust system for an engine according to claim 1, wherein the predetermined region to which the reinforcing member is fixed is located downstream of the catalyst device disposed in the exhaust passage. The engine exhaust device according to any one of claims 1 to 6,
The fixing means is welding,
An exhaust system for an engine, characterized in that fillet welding is performed on one section of the predetermined region partitioned by the joint, and plug welding is performed on the other section.

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