MXPA06011186A - Exhaust system of motorcycle - Google Patents

Abstract

PROBLEM TO BE SOLVED:To provide an exhaust device of a motorcycle capable of sufficiently securing the lowest road clearance and a banking angle of a vehicle while securing capacity of a muffler. SOLUTION:A plurality of exhaust pipes 60 extending out of an engine 6 and an exhaust pipe gathering part 70 are arranged on the right side of an oil pan 24, a first muffler 90 connected to this exhaust pipe gathering par 70 is arranged on the left side of the oil pan 24, and a second muffler connected to this first muffler 90 is arranged in the rear of the engine 6. COPYRIGHT:(C)2007,JPO&INPIT

Description

EXHAUST SYSTEM FOR MOTORCYCLE The present invention relates to an exhaust system for a motorcycle in which a motor main body of a multi-cylinder engine has an oil collector in a lower portion thereof, and is installed in a body of the engine. vehicle, and a muffler having plural expansion chambers is connected to a downward side of an assembled portion of the plural exhaust pipes extending outwardly from the respective cylinders of the main engine body, respectively. Up to now, it is known that an exhaust system for a motorcycle in which a muffler is connected to the exhaust pipes extending from the respective cylinders of the multi-cylinder engine is placed on the underside of the main body of the engine. In the escape device of this type, for example, as disclosed in JP-A No. 2004-345642,. the plural exhaust pipes are distributed to the right and left of an engine oil sump, and a cylindrical muffler that is substantially regular in the section is placed immediately below the sump. However, in the related exhaust system of this type, because the muffler is located immediately below the engine oil sump, it is difficult to ensure the minimum lower headroom or cant angle of the vehicle. in the case of trying to ensure the capacity of the silencer. The present invention has been made in view of the above circumstances, and therefore it is an object of the invention to provide an exhaust system for a motorcycle that eliminates the above problem with the related technique and is capable of sufficiently securing the height minimum lower free and cant angle of the motorcycle while ensuring the capacity of the muffler. In order to address the above problem, according to a first feature of the present invention, an exhaust system for a motorcycle is provided in which a motor main body of a multi-cylinder engine has an oil collector in a portion lower thereof and is mounted on a vehicle body and a muffler having plural expansion chambers is connected to a downward side of a mounted portion of a plurality of exhaust pipes extending outwardly from the respective cylinders of the main body of the vehicle. engine, respectively, wherein the muffler includes a first expansion chamber that is connected to the mounted portion and the other expansion chambers that are continuous to the first expansion chamber, the respective exhaust pipes and the mounted portion are placed in a side of the sump, the first expansion chamber is placed on the other side of the oil sump, and the other The expansion chambers are placed in the rear part of the main body of the engine. According to the configuration of the first characteristic above, the respective exhaust pipes and the assembled portion are placed on one side of the oil collector, the first expansion chamber is placed on the other side of the oil collector, and the other chambers of expansion are placed on the back of the main body of the engine. With the above configuration, as compared to the related technique where the muffler is placed immediately below the oil sump, the minimum lower headroom and superelevation angle of the motorcycle can be adequately secured at the same time as the capacity is secured of the silencer. In addition, as the heavy load constituting the exhaust system is concentrated under the engine, it is possible to lower the center of gravity of the motorcycle to the level and concentrate the mass. Also, in accordance with a second feature of the present invention, in addition to the configuration of the first feature above, the oil pan has an upside down portion that is turned upside down in the lower portion thereof., the respective exhaust pipes and the assembled portion are placed on a side surface of the turned upside down portion, and the first expansion chamber is placed on the other side surface of the turned upside down portion. With the above configuration, it is possible to increase the capacity of the first expansion chamber at the same time that the right and left weights are balanced with each other. Also, in accordance with a third feature of the present invention, in addition to the configuration of the second preceding feature, one side of the upside-down portion is tilted so that it is placed inwardly along the widthwise direction of the vehicle to the underside and the other side of the upside-down portion has a portion of side plate that is substantially orthogonal to the bottom surface of the oil pan and extends vertically, and a stitch portion extending from the end upper portion of the side plate portion toward the outer side so that it has a substantially L-shaped shape. The exhaust pipes that are placed on the outer side of a side surface are connected to the first expansion chamber that is placed on the outer side of the other side surface so that it positions at least a part of the first expansion chamber on the underside of the seam portion from the rear side of the oil pan. According to the previous configuration, because the exhaust pipes that have a high degree of freedom of tracing are placed on one side of the turned upside down portion, it is possible to ensure the capacity of the oil sump while avoiding that the lower portion of the main body of the engine is increased in size. As the first expansion chamber is placed on the outer side of the other side surface of the turned upside down portion so that at least a portion of the first expansion chamber is positioned on the underside of the sewing portion, it is possible to suitably securing the cant angle when the motorcycle is tilted to a side where the first expansion chamber is disposed. According to a fourth feature of the present invention, in addition to the configuration of any of the above first to third characteristics, a catalyst converter is placed on one side of the oil collector. According to the above configuration, the catalyst converter can be placed efficiently in a narrow space on one side of the oil sump. Furthermore, according to a fifth feature of the present invention, in addition to the configuration of any of the first to third characteristics, a container body constituting the first expansion chamber has a substantially triangular shape in the cross section and placed at along the surface which is inclined obliquely upwards towards the exterior side in the front view of the vehicle, and the plural exhaust pipes are placed along a surface sloping obliquely upwards towards the exterior side of the vehicle. front view of the vehicle as opposed to the container body. According to the above configuration, it is possible to efficiently ensure the cant angle when the vehicle body is in cant beside the first expansion chamber, and it is possible to efficiently secure the cant angle when the vehicle body It's on the cant side of the exhaust pipe. Also, the appearances of the container body constituting the first expansion chamber and the exhaust pipes are symmetrical, thereby making it possible to obtain an excellent appearance. The foregoing and other objects, features and benefits of the present invention will be apparent from the description of the preferred embodiments that will be described in greater detail with reference to the accompanying drawings. Figures 1 to 8 show a first embodiment of the present invention. Figure 1 is a side view showing the main portion of the motorcycle, Figure 2 is a perspective view of Figure 1, Figure 3 is a perspective view showing a part of the exhaust device, Figure 4 is a partially sectioned plan view of the exhaust device shown in the Figure 3, Figure 5 is a cross-sectional view taken along a line 5-5 of Figure 4, Figure 6 is a rear view of the oil collector taken from an opposite side of Figure 2, Figure 7 is a side view of longitudinal section showing the remaining portion of the exhaust device, Figure 8 is a cross-sectional view taken along a line 8-8 of Figure 7, and Figure 9 is a perspective view of a device escape according to a second embodiment. A first embodiment of the present invention will be described with reference to Figures 1 to 8. First, with reference to Figure 1, the vehicle body B of the motorcycle has a steering tube 5 at a front end thereof , a front fork 6 that rotatably holds a front wheel WF is supported by the steering tube 5 in a controllable steering mode, downwardly extending pivot platforms 8 integrate with the rear portion of a pair of frames main right and left 7 extending from the steer tube 5 to the rear side. In addition, the forward ends of the seat rails 9 extending back and up engage the rear portions of both main frames 7, the intermediate portions of the pivot platforms 8 in the vertical direction engage with the forward ends of the rear seats. the rear frames 10 extending back and up towards the underside of the seat rails 9, and connecting elements 11 are mutually connected between the seat rails 9 and the rear frames 10. In addition, the upper portions of the Engine hanging brackets 12 extending downward engage the steering tube 5 and the forward portions of the main frames 7. A main body of the engine 13 of a four-cylinder E engine in which four cylinders are arranged in parallel It is placed on the underside of the main frames 7 in the widthwise direction of the vehicle body B. The body or main motor 13 is supported by the intermediate portions and the lower portions of the pivot platforms 8 in the vertical direction as well as the lower portions of the hanging supports of the engine 12. The main body of the engine 13 includes a crankcase 14, a cylinder block 15 which is joined to the upper portion of the crankcase 14, a cylinder head 16 which is joined to the upper portion of the cylinder block 15, a head cover 17 which is joined to the upper portion of the cylinder head 16, and an oil collector 18 which is joined to the lower portion of the crankcase 1. The main body of the engine 13 is installed in the body of the vehicle B at a position where an axial line of the cylinder Cl tilts forward and upwards. A crankshaft 19 having an axial line extending in the widthwise direction of the body of the vehicle B is supported by a rotatable capacity by the crankcase 14. A transmission case 20 housing a transmission (not shown) that changes the The crankshaft rotation output 19 is positioned in the rear portion of the cylinder block 15 in a state where the transmission case 20 is installed in the motorcycle and is integrated in the crankcase 1. The brackets 21 and 22 are fastened to the intermediate portions and the lower portions of the pivot platforms 8 in a vertical direction, and the upper portions and the lower portions of the transmission case 20 are fastened to the brackets 21 and 22. , the brackets 23 are fastened to the lower portions of the motor suspension brackets 12, and the front end of the cylinder block 15 is fastened to the brackets 23. A rear wheel WR is supported with rotatability by the rear portion of a swingarm 24, and the forward portion of the swingarm 24 is slidably supported by pivot platforms 8 between the brackets 21 and 22 through a spindle 25. A reaction unit 26 is placed between the rear portions of the frames 7 the oscillating arm 24. In addition, the rotational power of an output shaft 27 of the transmission is transmitted to the rear wheel WR through a chain transmission means 31 which includes a drive gear 28 which is fixed to the output shaft 27, a driven gear wheel (not shown) that is fixed to the shaft of the rear wheel WR, and a worm chain threaded on the drive gear 28 and the driven gear. The intake ports (not shown) which are arranged in parallel at intervals determined in the widthwise direction of the vehicle body B open on the rear surface of the cylinder head 16 in the respective cylinders. The respective intake ports are connected with an intake device 33. The intake device 33 includes regulator bodies 34 which are connected to the respective intake ports, individually, and an air filter 35 which is commonly connected to the rising ends of the intake manifold. the throttle bodies 34. The admission axial lines C2 of the intake ducts 36 that are formed within the respective throttle bodies 34 are substantially orthogonal to the axial lines of the cylinder Cl that lean forward and upward and extend back and up. In addition, the fuel injection valves 37 corresponding to the respective cylinders, individually, are placed to the respective throttle bodies 34. The exhaust ports 38 which are arranged in parallel at intervals determined in the widthwise direction of the vehicle body B open on the front surface of the cylinder head 16 in the respective cylinders. The respective exhaust ports 38 are connected to an exhaust device 40 having four exhaust pipes 39A, 39B, 39C and 39D having the rising ends connected to the respective exhaust ports 38, individually. The exhaust device 40 extends in the direction of the right side of the rear wheel WR through the right side, the rear side and the left side of the oil collector 18 in the lower portion of the main body of the engine 13. The radiator 44 is placed on the front of the hanging bracket 12, and the radiator 44 is supported by the steering tube 5 and the hanging supports of the engine 12. On the other hand, a water pump 45 which is driven by rotation by a transmission power of the crankshaft 19 is attached to the left surface of the engine. the transmission case 20 and cooling water which has been cooled by the radiator 44 is sucked into the water pump 45 through a first cooling water hose 46. Incidentally, the cylinder block 15 and the cylinder head 16 they are equipped with a cooling jacket (not shown), and cooling water that is discharged from the water pump 45 is supplied to the cooling jacket within the cylinder block 15 via a second cooling water hose 47. In addition, a path of cooling water exiting from the cooling jacket inside the cylinder head 16 is changed by a thermostat 48 according to a cooling water temperature. That is, a percentage of an amount of water that is returned to a water pump 45 for the amount of water that is supplied to the radiator 44 in the cooling water that is drawn from the cooling jacket into the cylinder head 16. it is adjusted by means of the thermostat 48. The thermostat 48 and the water pump 45 are connected by a third cooling water hose 49 which guides the cooling water which is returned to the side of the water pump 45 and the thermostat 48 and the radiator 44 is connected by a fourth cooling water hose 50 which is supplied to the radiator side 44. With reference to Figures 2 to 4, the exhaust device 40 includes four exhaust pipes 39A to 39D having rising ends connected to the respective exhaust ports 38 on the front surface of the cylinder head 16, individually, an assembly exhaust pipe 51 as an assembled portion that is commonly connected to the ends descending from said exhaust pipes 3 A to 39D, a first connection pipe 52 with an upward end connected to the downstream end of the assembly exhaust pipe 51, a catalyst converter 53 having the rising end connected to the downstream end of the first connecting tube 52, and an MI silencer that is connected to the downstream end of the catalyst converter 53. The MI muffler includes a first portion of the muffler 54 having a first expansion chamber 59, a second portion of muffler 55 having a second expansion chamber 69, into which an exhaust gas is introduced from the first portion of the muffler 54, a second connection tube 56 that introduces the exhaust gas from the second muffler portion 55, and a third portion of the muffler 57 that has a third expansion chamber 79 (see Figure 7) and having the rising end connected to the downward end of the second tube 56. The four exhaust pipes 39A to 39D extending from the front surface of the cylinder head 16 downwards have such a curvature that they are placed on one side (right side in this embodiment) of the oil collector 18. In addition, the assembly exhaust pipe 51 is substantially Y-shaped by integrating a first branch pipe portion 51a connecting the descending ends of the two remaining exhaust pipes 39c and 39D in the four exhaust pipes .39A to 39D, and a portion of assembly tube 51c that connects the descending ends of the first and second branched tube portions 51a and 51b commonly. The assembly exhaust pipe 51 is located on one side of the oil collector 18. On the other hand, the sectional configuration of the container body 58 forming the first expansion chamber 59 is triangularly shaped in the cross section with an oblique surface 58a which is the interior position along the widthwise direction of the vehicle body B towards the underside as the outer surface as shown in Figure 5. A support plate 66 is fixed to the upper front surface of the cylinder outer 60 in the container body 58 of the first portion of the muffler 54, and the support plate 66 is supported to a support portion 14a placed in the crankcase 14 of the main body of the engine 13 through the mounting rubber 67. A container body 68 of the second portion of the silencer 55 is joined to a rear end of the outer cylinder 60 in the first portion of the muffler 54 so as to extend around the rear side of the oil sump 18. A second expansion chamber 69 continues to the first expansion chamber 59 is formed within the container body 68 , and the second expansion chamber 69 is placed between the oil collector 18 and the rear wheel WR on the rear side of the main body of the engine 13. In addition, the outer periphery of an insulation board 70 for separating the first and second chambers of expansion 59 and 69 of one another is fixed to the inner surface of the end of the side of the first portion of the muffler 54 in the container body 68 of the second portion of the mu In addition, the support plate 71 is fixed to the upper surface of the container body 68 of the second portion of the silencer 55, and the support plate 71 is held to the body of the vehicle B through the mounting rubber that it is not shown. The majority of a box 72 of the catalyst converter 53 is housed in the second expansion chamber 69. The box 72 is formed by attaching a rising end of a second pipe element 74 with a larger diameter portion 74a on a rising half-side with a downward end of a first tube element 73 with larger diameter portion 73a on a downward half-side. The larger diameter portion 74a of the second tube member 74 is filled with a catalyst 75. On the other hand, the rising end of the first tube member 73 hermetically enters the container body 58 of the second portion of the muffler 55 and protrudes from right side. The downstream end of the first connection tube 52 having an upward end connected to the assembly tube portion 51c of the assembly exhaust pipe 51 is connected to the rising end of the first tube member 73, i.e. the upward end of the converter of catalyst 53. A spacer 76 separating the first expansion chamber 59 in right and left portions in a portion proximate to the second expansion chamber 69 is fixed to a portion of the side of the insulation plate 70 of the inner cylinder 61 in the container body 58 of the first muffler portion 54. A first conduit tube 77 having the downward end in communication with the first expansion chamber 59 on the left side of the separator 76 sealingly enters the insulation plate 70, and the The upward end of the first conduit tube 77 is connected to the descending end of the casing 72 of the catalyst converter 53, ie the end desce of the second pipe element 74. That is, the exhaust pipes 39A to 39D which are located on one side of the oil sump 18 are connected to the first expansion chamber 59 which is located on the other side of the oil sump 18 through the assembly exhaust pipe 51, the first connection pipe 52, the catalyst converter 53, and the first pipeline 77 from the rear side of the oil collector 18. A second pipeline 78 having the end ascending in communication with the first expansion chamber 59 on the right side of the separator 76 hermetically penetrates the insulating plate 70, and the downward end of the second conduit tube 78 opens to the second expansion chamber 69. That is, the gas of exhaust inside the first expansion chamber 59 is introduced into the second expansion chamber 69 through the second conduit tube 78. If Figures 2 and 6 are observed, the oil collector 18 has a p turned upside down 18d which is turned upside down into a lower portion, and a first side surface 18a of both the left and right side surface of the upside down portion 18d is tilted to be placed inwardly along the widthwise direction of the vehicle body B towards the lower side. The four exhaust pipes 39A to 39D which are directed towards the first lateral surface 18a are positioned vertically so as to be disposed along the first inclined lateral surface 18a.

In addition, the intermediate portion 18aa positioned along the vertical direction of the first side surface 18a is inclined to be positioned inwardly in the widthwise direction of the vehicle body B towards the rear side as clearly shown in Figure 6. The other second side surface 18b of both the left and right side surfaces of the upside down portion 18d has a side plate portion 18ba that is substantially orthogonal to the bottom surface 18c of the oil pan 18 and extends vertically, and a seaming portion 18bb extending from an upper end of the side plate portion 18ba to the outer side so that it has a substantially L-shaped shape. On one side (right in this embodiment) of the portion turned upside down 18d the respective exhaust pipes 39A to 39D, the assembly exhaust pipe 51 and the first silencer portion 54, i.e. , the first expansion chamber 59. At least a part, half in this embodiment, of the first portion of the muffler 59 is placed on the underside of the seam portion 18bb, and is installed on the outer side of the second side surface 18b, that is, on the other side (left side of this embodiment) of the inverted portion 18d. On the other hand, as clearly shown in Figure 2, the container body 58 having a substantially triangular shape in the cross section to form the first expansion chamber 59 is installed along a plane LL that slopes obliquely upwards. facing the outer side of the front view of the vehicle and the plural exhaust pipes 39A to 39D are placed along a plane LR that slopes obliquely upwards facing the exterior side of the front view of the vehicle as opposed to the body of the vehicle. vessel 58. Both planes LL and LR are symmetrically placed with respect to the centerline of the LC vehicle. Furthermore, the majority of the support portion 14a is placed in the crankcase 14 so as to support the support plate 66 which is fixed on the front upper surface of the outer cylinder 60 in the container body 58 of the first portion of the silencer 54 The majority of the support portion 14a is placed in the crankcase 14 so as to be positioned above an extension of the bottom surface of the seam portion 18bb on the second side surface 18b to the exterior side. This structure of the support portion 14a makes it possible to support the body of the container 58 at the same time that the sectional area of the first expansion chamber 59 is sufficiently secured. In addition, an oil leakage opening 80 is defined between the respective exhaust pipes. 39A to 39D and the first muffler portion 54, i.e., the first expansion chamber 59 in front of the oil sump 18, and the opening 80 is closed by means of a removable attached lid 94 such as a bolt. With reference to Figures 7 and 8, a container body 81 of the third portion of the muffler 57 includes an outer cylinder 82 extending anteriorly of the motorcycle, an inner cylinder 83 that is coaxially positioned within the outer cylinder 82, a tube conical 82 having a smaller diameter towards the forward direction and joins with the forward end of the outer cylinder 82, and a tail plate 85 which is joined with the rear end of the inner cylinder 83 as well as the rear end of the cylinder 82 and closes the rear ends of the outer cylinder 82 and the inner cylinder 83. The container body 81 is placed on the rear of the main body of the engine 13 and on the right side of the rear wheel WR. A third expansion chamber 79 is defined within the container body 81. That is, the third expansion chamber 79 is also placed on the rear of the main body of the engine 13 and on the right side of the rear wheel WR. A ring-shaped spacer 86 and a glass wool 87 are interposed between the outer cylinder 82 and the inner cylinder 83. The conical tube 84 of the container body 81 is connected to the lower end of the second connection tube 56. In addition, a support element 88 is fixed on the inner surface of the front end of the inner cylinder 83. The forward end of an air emission tube 89 that hermetically penetrates the tail plate 85 so as to open the third expansion chamber 79 to the atmosphere is supported by the support element 88, and the rear portion of the emission tube to the atmosphere 89 is welded to the tail plate 85. Furthermore, the intermediate portion of the emission tube to the atmosphere 89 is covered with a noise-absorbing cylinder 90 and a large number of small openings 91 are defined in the emission tube to the atmosphere 89 in a portion corresponding to the noise-absorbing cylinder 90. A space between the noise-absorbing cylinder 90 and the emission tube to the atmosphere 89 is filled with a glass wool 92. On the other hand, as clearly shown in Figure 8, the sectional configuration of the container body 81 that forms the third chamber of expansion 79 has a triangular shape with an oblique surface 81a which is the internal position along the widthwise direction of the vehicle body B towards the underside as the outer surface.

Subsequently, the operation of the first embodiment will be described. The first expansion chamber 79 is located on the side of the oil collector 18, and even in the case of sufficiently securing the capacity of the first expansion chamber 59, it can be avoided that the lower portion of the engine E that includes the Exhaust device 40 enlarges anteroposteriorly. In addition, the four exhaust pipes 39A to 39D which are placed on one side (right side in this embodiment) of the oil sump are connected to the first expansion chamber 59 which is located on the other side (left side of this). embodiment) of the oil sump 18, from the rear side of the oil sump 18. As a result, the structural elements of the exhaust device 40 are not placed on the underside of the oil sump 18, thereby making it possible to prevent a position in which the main body of the engine 13 is installed is superior to reduce the center of gravity in the level. On the other hand, the silencer MI includes the first expansion chamber 59 which is connected to the assembly exhaust pipe 51, and the second and third expansion chambers 69 and 79 continue to the first expansion chamber 59. The respective exhaust pipes 39A to 39D and the exhaust assembly tube 51 are placed on one side (right side of the oil pan 18. The first expansion chamber 59 is placed on the other side (left side) of the oil pan 18. The second and third expansion chambers 69 and 79 are placed in the rear part of the main body of the motor 13. With the above configuration, as compared to the related technique in which the muffler is positioned immediately below the oil sump 18, the headroom The lower minimum and the cant angle of the motorcycle can be secured sufficiently while ensuring the full capacity of the expansion chambers 59, 69 and 79. In addition, the lower portion of the motorcycle E which includes the exhaust system 40 can be formed in a compact form. In addition, since the heavy load constituting the exhaust system 40 is concentrated below the engine E, it is possible to reduce the center of gravity of the motorcycle in the level and concentrate the mass. Furthermore, it is possible to ensure sufficient capacity as the total expansion chamber even if the capacity of the third expansion chamber 79 is reduced as much as possible. Therefore, the third expansion chamber 79, that is, the third portion of the silencer 57, is formed compactly so that it does not extend from the rear wheel WR to the rear side, thus enabling the entire motorcycle to be compact and concentrate the mass of the weight and contribute to an improvement in the performance of the movement of the motorcycle. Also, the oil pan 18 has an upside down portion 18d that is turned upside down in the lower portion thereof, the respective exhaust pipes 39A to 39D and the assembly exhaust pipe 51, and the first plenum chamber. expansion 59 are placed on both sides of the turned upside down portion 18d. With the above configuration, it is possible to increase the capacity of the first expansion chamber 59 at the same time that the right and left weights are balanced with each other. In addition, the first side surface 18a which is one of both right and left surfaces (right side) of the upside down portion 18d of the oil collector 18 is thereby tilted to be positioned inwardly in the widthwise direction of the vehicle body (B) to the underside. The exhaust pipes 39A to 39D that are small in the sectional area of the duct and the outer side of the first side surface 18a. As a result, the capacity of the oil sump 18 can be secured while preventing the lower portion of the engine E from enlarging in size. Also, the second side surface 18b which is the other of the two left and right side surfaces (left side) of the upside down portion 18d of the oil sump 18 has the side plate portion 18ba which is substantially orthogonal to the bottom surface 18c of the oil collector 18 and extending vertically and the seam portion 18bb which extends from the upper end of the side plate portion 18ba to the outer side so as to be substantially L-shaped. At least a portion of the first portion of the muffler 54 constituting the first expansion chamber 59 is placed in the lower side of the sewing portion 18bb and is placed on the outer side of the second side surface 18b. As a result, it is possible to sufficiently ensure the cant angle when the motorcycle is placed in cant towards the side (left side) where the first expansion chamber 59 is placed. Also, the sectional configuration of the container body 58 of the first portion of muffler 54 is triangular in shape with the oblique surface 58a which is the interior position along the widthwise direction of the vehicle body B towards the underside as the surface. As a result, it is easier to secure the cant angle when the motorcycle is placed on the left side of the cant. Furthermore, the container body 58 constituting the first expansion chamber 59 has a substantially triangular shape in the cross section and is positioned along the plane LL that inclines obliquely upwards in front of the exterior side in the front view of the vehicle and the plural exhaust pipes 39A to 39D are placed along a plane LR that slopes obliquely upwards to the exterior side of the front view of the vehicle as opposed to the container body. As a result, it is possible to efficiently secure the cant angle when the vehicle body is in cant towards the side of the first expansion chamber 59, and it is possible to efficiently secure the cant angle when the vehicle body is in cant towards the side of the exhaust pipes 39A to 39D. In addition, the appearances of the container body 58 constituting the first expansion chamber 59 and the exhaust pipes 39A to 39D are symmetrical, thus making it possible to obtain an excellent appearance. In addition, the four exhaust ports 38 are placed on the front surface of the cylinder head 16 in the main engine body 13 to be aligned in the widthwise direction of the vehicle body B. The four exhaust pipes 39A a 39D which are connected to these exhaust ports 38, individually, are placed on the outer side of the first side surface 18a and extend rearwardly. The descending ends of the exhaust pipes 39A to 39D are commonly connected to the first expansion chamber 59 which is placed on the outer side of the second side surface 18b of the oil sump 18. With the above configuration, in the engine E of multiple cylinders in which plural cylinders are aligned in the widthwise direction of the vehicle body B, the plural exhaust pipes 39A to 39D and the first expansion chamber 59 are divided to the left or right side of the oil sump 18, thus making it possible to balance the weight balance in the lateral direction of the engine E. Also, the exhaust pipes 39A to 39D move vertically along the first lateral surface 18a of the oil collector 18, thus making it possible to ensure Suitably the cant angle when the motorcycle is in cant towards the side where the respective exhaust pipes 39A to 39D are placed. On the other hand, the sectional configuration of the container body 81 of the third muffler portion 57 forming the third expansion chamber 79 has a triangular shape with an oblique surface 81a which is the interior position along the widthwise direction of the container. the vehicle body B towards the lower side as the outer surface. As a result, when the configuration of the first side surface 18a of the oil collector 18 and the arrangement of the respective exhaust pipes 39A to 39D is determined to ensure the cant angle when the motorcycle is in cant towards the side where the respective exhaust pipes 39A to 39D are positioned, that is, to the right side, the third portion of muffler 57 is not an obstacle to securing the cant angle. Also, the intermediate portion 18aa disposed along the vertical direction of the first side surface 18a which is a side where the respective exhaust pipes 39A to 39D are placed is inclined to be positioned inwardly in the widthwise direction of the body from vehicle B to the rear side. As a result, when the plural exhaust pipes 39A to 39D are grouped on the rear side of the oil collector 18, the sectional configuration of the grouped portion is able to approach the circle, thereby improving the exhaust efficiency. Further, since the grouped portion may be arranged so that the lower portion of the engine E does not extend to the outer side even in a state where the sectional area of the grouped portion is maintained, it is possible to secure the cant angle by stopping the motorcycle. it is in cant towards the side where the exhaust pipes 39A to 39D are placed. On the other hand, the oil escape opening 80 is defined on the front surface of the oil sump 18 between the respective exhaust pipes 39A to 39D and the first muffler potion 5. With the above structure, access is facilitated due to the tool at the time of exchanging the oil in the oil sump 18 and the structural element of the motorcycle is not placed on the underside of the opening 80. As a result, as much as possible is avoided. It is possible for the oil to adhere to the structural elements at the moment of exchanging the oil, thus making it possible to increase the maintenance property. Figure 9 shows a second embodiment. The parts corresponding to those of the first embodiment are designated by the same reference symbols and appear only in the figures, and their detailed description will be omitted. An exhaust device 95 includes four exhaust pipes 39A to 39D, an assembly exhaust pipe 51 that are commonly connected to the descending ends of those exhaust pipes 39A to 39D, a catalyst converter 97 that includes a catalyst 96 in the same and having an upward end connected to the downstream end of the assembly exhaust pipe 51, a first connection pipe 98 having an upward end connected to the downstream end of the catalyst converter 97, and a muffler M2 which is connected to the downstream end of the first connection tube 98. The silencer M2 has a first portion of muffler 99 having a first expansion chamber 102, a second portion of muffler 100 having a second expansion chamber 104, in which the exhaust gas is introduced from the first portion of the muffler 99, a second connection tube 101 guiding the exhaust gas from the second muffler portion 100, and a t erber portion of muffler 57 having the third expansion chamber 79 (refer to Figure 7 of the first embodiment) and having the rising end connected to the descending end of the second connection tube 101. The respective exhaust pipes 39A to 39D , the assembly exhaust pipe 51 and the catalyst converter 97 are located on the right side of the oil sump 18. In addition, the first muffler portion 99 and the second muffler portion 100 are aligned anteroposteriorly with the first portion of the muffler. 99 located in the previous position, and placed on the left side of the oil collector 18. On the other hand, a container body 103 of the first portion of the muffler 99 which constitutes the first expansion chamber 102 and a container body 105 of the second portion of the silencer 100 constituting the second expansion chamber 104 are mutually joined so as to be aligned anteroposteriorly, and an isolation plate 106 separating the first and second expansion chambers 102 and 104 from one another is fixed to either of both container bodies 103 and 105. In addition, a spacer 107 separating the first expansion chamber 102 at the right and left portions at a portion near the second expansion chamber 104 is fixed to the container body 103 of the first portion of the silencer 99. first connection tube 98 is bent into a substantially U-shape on the rear side of the oil sump 18. The first connection tube 98 having the rising end connected to the downward end with the first expansion chamber 102 on the left side of the separator 107, and hermetically penetrates the container body 105 and the isolation plate 106 of the second portion of the silencer 100. In addition, a conduit tube 108 having an open end towards the first expansion chamber 102 on the right side of the separator 107 penetrates the isolation plate 106 and is fixed to the isolation plate 106. The other end of the conduit tube 108 communicates with the second chamber of expansion 104. In addition, the upward end of the second connection tube 101 communicates with the second expansion chamber 104, and connects to the container body 105 of the second portion of the silencer 100. A third portion of the silencer 57 which is placed on the right side of the rear wheel WR (see first embodiment) is connected to the downward end of the second connecting tube 101. The exhaust device 95 according to the second embodiment is different from the exhaust device 40. according to the first embodiment in which the second expansion chamber 104 is placed in the back of the first expansion chamber 102 and the part of the main body of the motor 13 and that the catalyst converter 97 is placed on the right side of the oil collector 18. However, the second embodiment has the same advantages as those of the first embodiment. On the other hand, since the catalyst converter 97 is placed on the right side of the oil sump 18, the catalyst converter 97 can be efficiently placed in a narrow space on the right side of the oil sump 18. The capacity of the muffler M2 It can be secured efficiently compared to a box where the converter converter is housed in the muffler. Embodiments of the present invention were described above, however, the present invention is not limited to the foregoing embodiments, and it is possible to change the design without departing from the present invention in many ways from the claims.

Claims (5)

1. CLAIMS 1. An exhaust system for a motorcycle wherein a main engine body (13) of a multi-cylinder engine € has an oil collector (18) in a lower portion thereof and is installed in a vehicle body ( B) and a muffler (MI, M2) having a plurality of expansion chambers (59, 69, 79; 102, 104, 79) is connected to a downward side of an assembled portion (51) of a plurality of tubes of exhaust (39A, 39B, 39C, 39D) extending outwardly from the respective cylinders of the main engine body (13), respectively, wherein the silencer (MI, M2) includes a first expansion chamber (59, 102) which is connected to the assembled portion (51) and the other expansion chambers (69, 79; 104, 79) which are continuous to the first expansion chamber (59, 102). the respective exhaust pipes (39A to 39D) and the assembled portion (51) are placed on one side of the oil sump (18), the first expansion chamber (59, 102) is placed on the other side of the oil sump (18), and the other expansion chambers (69, 79; 104, 79) are placed on the rear of the main body of the motor (13).
2. 2. The exhaust system for a motorcycle according to Claim 1, wherein the oil collector (18) has an upside down portion (I8d) that is turned upside down in the lower portion thereof, the respective tubes of Exhaust (39A to 39D) and the assembled portion (51) are placed on one side of the turned upside down portion (18d), the first expansion chamber (59, 102) is placed on the other side of the turned upside down portion (18d)
3. 3. The exhaust system for a motorcycle according to claim 2, wherein a side surface (18a) of the upside-down portion (18d) has a slope such that it is positioned inwardly along the width of the vehicle (B) to the bottom side, the other side surface (18b) of the upside-down portion (18D) has a side plate potion (18ba) which is substantially orthogonal to the bottom surface (18c) of the oil collector (18) and extends vertically, and a seam portion (18bb) extending from the upper end of the side plate portion (18b). ) to the outer side so that it is substantially L-shaped, and the exhaust pipes (39A to 39D) which are placed on the outer side of the side surface (18a) are connected to the first expansion chamber (59, 102). ) that is placed on the outer side of the other side surface (18b) so that at least a portion of the first expansion chamber is positioned on the underside of the seam portion (18bb) of the rear side of the oil pan (18)
4. 4. The exhaust system for a motorcycle according to any of Claims 1 to 3, wherein a catalyst converter (97) is placed on one side of the oil sump (18).
5. 5. The exhaust system for a motorcycle according to any of Claims 1 to 3, wherein a container body (58) constituting the first expansion chamber (59) has a substantially triangular shape in the cross section and is placed along a surface sloping obliquely upward facing the exterior side in the front view of the vehicle, and the plurality of the exhaust pipes (39A to 39D) is positioned along a surface sloping obliquely upwards facing the outside of the front view of the vehicle, as opposed to the container body.