JP4441389B2 - Exhaust muffler structure in motorcycles - Google Patents

Description

The present invention includes a first case that forms a first expansion chamber that leads to an exhaust pipe that guides exhaust gas from an engine, and a second case that forms a second expansion chamber into which exhaust gas from the first expansion chamber is introduced. The present invention relates to an exhaust muffler structure in a motorcycle.

Such exhaust mufflers are already known, for example, from Patent Document 1 and Patent Document 2.
Japanese Patent Publication No. 7-76527 Japanese Patent Publication No. 6-50052

  In those disclosed in Patent Documents 1 and 2, the first case forming the first expansion chamber is configured by joining the peripheral edges of a pair of case halves facing each other to form the second expansion chamber. The second case is configured such that a part thereof is a cylindrical body. However, since the exhaust pressure introduced into the first expansion chamber is relatively high, in the first case having a structure in which the peripheral portions of the pair of case halves are combined, the outer plate noise is likely to occur due to the exhaust pulsation. In order to prevent this, it is necessary to increase the rigidity of the first case. For this reason, in what was disclosed by patent document 1 and 2, both the case half bodies which comprise a 1st case are shape | molded so that it may have an unevenness | corrugation, and it causes the increase in processing cost.

  In order to solve such a problem, it is conceivable that both the first and second cases are formed in a cylindrical shape having high pipe rigidity, which is effective for outer panel noise but requires an exhaust muffler. The space efficiency with respect to the capacity is inferior, and it is difficult to apply to a scooter type motorcycle. It is also possible to make the exhaust muffler casing into a single cylindrical shape without dividing the casing into the first and second cases. However, in such an exhaust muffler, the outer diameter of the casing is large when trying to secure the required capacity. Therefore, it protrudes from the width of the vehicle body, and the length is also limited, so there is a limit to the increase in capacity.

The present invention has been made in view of such circumstances, and an exhaust muffler structure in a motorcycle that can easily improve the space efficiency and increase the capacity while preventing the noise of the outer plate by eliminating the processing that increases the cost. The purpose is to provide.

To achieve the above object, a first aspect of the present invention, a first expansion chamber communicating with the exhaust pipe for guiding exhaust gas from the engine, and a second expansion chamber exhaust gas from the first expansion chamber is introduced in the exhaust muffler structure in a motorcycle equipped with an exhaust muffler comprising,
A casing of the exhaust muffler is formed in a cylindrical first case that extends in the longitudinal direction of the vehicle body and forms the first expansion chamber therein, and has a shape that bulges upward from the first case in a side view of the vehicle. the second expansion chamber is further configured with a second casing to form a, together with the second case is configured by the peripheral portions of the pair of case halves which are respectively formed opposite to each other are coupled like a bowl The lower parts of the two case halves are respectively coupled to the upper part of the first case, and the joints of the two case halves to the upper part of the first case are connected to the intermediate parts in the longitudinal direction of the two case halves. It is characterized by being spaced apart from each other in the circumferential direction of the first case .

According to a second aspect of the invention, in addition to the configuration of the first aspect of the invention, the casing is formed in a circular arc shape in which the upper outer periphery of the second case is bent substantially corresponding to the outer periphery of the rear wheel. A muffler protector that covers the first and second cases from above is integrally connected to a rear fender that is disposed on the side of the rear wheel and covers the rear wheel from above.

According to a third aspect of the present invention, in addition to the configuration of the first or second aspect of the invention, the first case includes a first expansion chamber and a third expansion that is blocked from the first expansion chamber. A chamber is formed, and the exhaust gas introduced into the second expansion chamber is guided to the third expansion chamber.

According to a fourth aspect of the present invention, in addition to the configuration of the first aspect of the present invention, a lower portion of the first expansion chamber is disposed at a position close to a lower end opening of the muffler protector portion. It is characterized by that.

According to a fifth aspect of the present invention, in addition to the configuration of the first aspect of the present invention, an electric motor capable of applying a driving force to a rear wheel is provided between the motor and the exhaust muffler. The motor is disposed so that the rear wheel is sandwiched from the left and right sides, and the rotational axis of the motor is on the front side of the center position in the front-rear direction of the exhaust muffler.

  According to the first aspect of the present invention, since the first case forming the first expansion chamber having a high exhaust pressure to be introduced is formed in a cylindrical shape having a high tube rigidity, it is possible to eliminate the need for processing that increases the cost. A pair of case halves in which the second case that can effectively prevent squealing and forms the second expansion chamber into which the exhaust gas whose exhaust pressure is lower than that of the first expansion chamber is introduced is bowl-shaped. Since the peripheral portions of the first and second cases are combined, it is possible to minimize the response of the outer plate noise in the second case, and the capacity can be easily increased. This makes it easy to increase the capacity of the entire exhaust muffler and to improve the space efficiency.

  According to the second aspect of the present invention, the exhaust muffler can be covered with the muffler protector part integrated with the rear fender part covering the rear wheel, and a compact appearance can be obtained.

According to the fifth aspect of the present invention, it is possible to more effectively prevent the electric motor from being affected by the heat generated by the exhaust muffler.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on one embodiment of the present invention shown in the accompanying drawings.

  1 to 6 show an embodiment of the present invention. FIG. 1 is a side view of a scooter type motorcycle, FIG. 2 is a sectional view taken along line 2-2 of FIG. 1, and FIG. 4 is a rear view of the exhaust muffler viewed from the direction of arrow 4 in FIG. 3, FIG. 5 is a sectional view taken along line 5-5 in FIG. 3, and FIG. 6 is a sectional view taken along line 6-6 in FIG. is there.

  First, in FIG. 1, this scooter type motorcycle is a hybrid type, and its body frame F includes a head pipe 12 that supports a front fork 11 that pivotally supports a front wheel WF at a lower end portion thereof, and a steering pipe 12 A front frame 13 extending rearward and downward from the head pipe 12, a pair of intermediate frames 14 branching left and right from the lower end of the front frame 13 and extending substantially horizontally rearward, and the rear of the intermediate frames 14 A pair of rear frames 15 extending from the end to the rear upward, and a bar-shaped steering handle 16 is connected to the upper portion of the front fork 11.

  The front part of the power unit P is supported so as to be swingable at the middle part in the front-rear direction of the rear frames 15. A rear cushion 17 is provided between one of the rear frames 15 and the power unit P. A rear wheel WR is pivotally supported at the rear of the power unit P.

  In FIG. 2, the power unit P includes a four-cycle engine E configured as a water-cooled single cylinder so that a driving force can be applied to the rear wheel WR, and a V-belt type that can change the output of the engine E steplessly. A continuously variable transmission 18, a start clutch 19 interposed between the engine E and the continuously variable transmission 18, an electric motor 20 capable of applying a driving force to the rear wheel WR, and between the electric motor 20 and the rear wheel WR And a one-way clutch 22 interposed between the continuously variable transmission 18 and the power transmission means 21.

  The engine body 25 of the engine E includes a crankcase 27 that rotatably supports a crankshaft 26 having a rotation axis parallel to the rotation axis of the rear wheel WR, a cylinder block 28 coupled to the crankcase 27, and a crankcase 27 And a head cover 30 coupled to the cylinder head 29 on the opposite side of the cylinder block 28.

  The cylinder block 28 is arranged so that the axis of the cylinder bore 31 provided in the cylinder block 28 is slightly horizontal as it rises slightly along the traveling direction of the motorcycle. A piston 32 is slidably fitted to the cylinder bore 31, and the piston 32 is connected to the crankshaft 26 via a connecting rod 33.

  A combustion chamber 34 is formed between the cylinder head 29 and the piston 32, and a spark plug 35 facing the combustion chamber 34 is attached to the left side surface of the cylinder head 29 in a state of facing forward in the traveling direction of the motorcycle. Between the cylinder head 29 and the head cover 30, a valve mechanism 37 including a cam shaft 36 having an axis parallel to the axis of the crankshaft 26 and rotatably supported by the cylinder head 29 is mixed into the combustion chamber 34. An intake valve (not shown) and an exhaust valve (not shown) for controlling the intake and exhaust of the air are accommodated so as to open and close, and are mounted on the right end of the camshaft 36 with the motorcycle facing forward in the traveling direction. , The rotational power from the crankshaft 26 is reduced to 1/2 by the timing transmission means 38 and transmitted.

  The right end portion of the crankshaft 26 penetrates the mounting base 39 attached to the right side of the crankcase 27 and the cylinder block 28 in a liquid-tight and rotatable manner, and the protruding portion from the mounting base 39 is the crankshaft 26. The outer rotor 41 is fixed, and the inner stator 42 constituting the ACG starter motor 40 in cooperation with the outer rotor 41 is fixed to the mounting base 39 so as to be surrounded by the outer rotor 41.

  A cooling fan 43 is fixed to the crankshaft 26 outside the ACG starter motor 40, and a radiator 44 is disposed at a position sandwiching the cooling fan 43 with the ACG starter motor 40. It is attached to the crankcase 27 and the cylinder block 28 via a shroud 45 surrounding the cooling fan 43. The radiator 44 is covered with a radiator cover 46 attached to the shroud 45, and a grill 47 for introducing cooling air from the outside by the cooling fan 43 faces the radiator 44. It is formed. Further, a discharge port 48 for discharging the air that has passed through the radiator 44 to the outside is provided in the shroud 45 on the side of the cooling fan 43.

  The V-belt type continuously variable transmission 18 is accommodated in a transmission case 50 that covers a part of the engine body 25 from the side and is connected to the engine body 25 and extends to the left side of the rear wheel WR. The transmission case 50 is fastened to the rear portion of the inner case 51 on the side opposite to the outer case 52, an inner case 51 integrally connected to the crankcase 27, an outer case 52 that covers the inner case 51 from the outside. A gear case 53.

  The continuously variable transmission 18 includes a drive pulley 54 attached to an end of the crankshaft 26 that enters the front portion of the transmission case 50 from the crankcase 27, an inner case 51, and an axis parallel to the crankshaft 26. A driven pulley 55 attached to an output shaft 57 that is rotatably supported by a gear case 53 and an endless V-belt 56 that transmits power from the drive pulley 54 to the driven pulley 55 are provided.

  The drive pulley 54 includes a fixed pulley half 58 that is attached to the crankshaft 26 via the starting clutch 19, and a movable pulley half 59 that can approach and separate from the fixed pulley half 58. The power that drives the movable pulley half 59 in the axial direction to change the width of the belt groove formed between the fixed pulley half 58 and the movable pulley half 59 is wound in the transmission case 50. The electric power is transmitted from the control electric motor 60 fixedly accommodated to the movable pulley half 59 via the gear reduction mechanism 61.

  The starting clutch 19 is a centrifugal clutch that transmits the power from the crankshaft 26 to the fixed pulley half 58 when the rotational speed of the crankshaft 26 is not less than a predetermined value, for example, 3000 rpm or more.

  The driven pulley 55 is slidably fitted to the inner cylinder 64 that allows relative rotation and coaxially surrounds the output shaft 57, and allows relative rotation around the axis and relative movement in the axial direction. An outer cylinder 65, a fixed pulley half 66 fixed to the inner cylinder 64, a movable pulley half 67 fixed to the outer cylinder 65 opposite to the fixed pulley half 66, the movable pulley half 67, and A torque cam mechanism 68 provided between the inner cylinder 64 and the outer cylinder 65 so as to apply an axial component force between the pulley halves 66 and 67 according to the relative rotational phase difference between the fixed pulley halves 66; A spring 69 is provided that exerts a spring force on the side where the movable pulley half 67 is brought close to the fixed pulley half 65 and is contracted between the inner cylinder 64 and the movable pulley half 67.

  Thus, the distance between the fixed pulley half 66 and the movable pulley half 67 in the driven pulley 55 is such that the axial force generated by the torque cam mechanism 68, the axial elastic force generated by the spring 69, and the fixed pulley half. 66 and the movable pulley half 67 is determined by a balance with the force from the V-belt 56 acting in the direction of separating the gap between the movable pulley half 67 and the drive pulley 54 by moving the movable pulley half 59 close to the fixed pulley half 58. When the winding radius of the belt 56 around the drive pulley 54 increases, the winding radius of the V belt 56 around the driven pulley 55 decreases.

  The electric motor 20 capable of applying power to the rear wheel WR is an outer case fixed to a motor case 71 fixed to the outer case 52 so as to close an opening 70 provided in a rear portion of the outer case 52 in the transmission case 50. The stator 72 and an inner rotor 73 that is mounted on the output shaft 57 so as not to rotate relative to the output shaft 57 are configured to transmit the rotational power to the output shaft 57 when the electric motor 20 is operated.

  The one-way clutch 22 is interposed between the inner cylinder 64 of the driven pulley 55 and the inner rotor 73 of the electric motor 20. The continuously variable transmission 18 outputs the output of the engine E to the output shaft 57. In this state, power can be transmitted from the inner cylinder 64 to the inner rotor 73. In other words, the one-way clutch 22 can transmit power in only one direction from the inner cylinder 64 to the inner rotor 73. Even if the electric motor 20 functions as a regenerative generator during regenerative braking, the rotational power of the inner rotor 73 remains. It does not reach the inner cylinder 64. Therefore, since it is not necessary to rotate the V-belt 56 at the time of regeneration, the power consumption can be improved.

  An axle 74 is rotatably supported on the inner case 51 and the gear case 53, and a hub 75 of the rear wheel WR is fixed to an end portion of the axle 74 protruding from the transmission case 50.

  The power transmission means 21 is a reduction gear train provided between the output shaft 57 and the axle 74, and the first case 77 provided on the output shaft 57, the inner case 51 and the gear in parallel with the output shaft 57 and the axle 74. A second gear 78 that is provided on an intermediate shaft 76 that is rotatably supported by the case 53 and meshes with the first gear 77, a third gear 79 that is provided on the intermediate shaft 76, and an axle that meshes with the third gear 79. And a fourth gear 80 provided at 74.

  An outside air intake port 81 for taking cooling air into the transmission case 50 is provided on the side wall of the outer case 52 facing the drive pulley 54 in the transmission case 50, and outside the drive pulley 54. A cooling fan 82 for dispersing cooling air taken in from the outside air intake port 81 in the transmission case 50 is attached to the end of the crankshaft 26.

  A filter case 83 is attached to the outer surface of the outer case 52 so as to cover the outside air intake port 81 from the outside, and the outside air introduced into the filter case 83 from the suction port 84 provided in the filter case 83 is filtered. The air is purified by passing through a filter element 85 provided in the case 83 and is sucked into the transmission case 50 from the outside air intake port 81.

  Referring also to FIG. 3, the intake system 88 of the engine E includes an air cleaner 89 that purifies external air, an intake hose 90 that guides purified air from the air cleaner 89, and a downstream end of the intake hose 90. The carburetor 91 to be connected and an intake pipe 92 connecting the upper side surface of the cylinder head 29 and the carburetor 91 in the engine E are provided, and the air cleaner 89 is rearward in a state of facing forward in the traveling direction of the motorcycle. The power unit P is disposed from the upper side to the rear side on the left side of the wheel WR.

  The exhaust system 94 of the engine E has an upstream end connected to the lower side surface of the cylinder head 29 and an exhaust pipe extending rearward toward the right side of the rear wheel WR while facing forward in the traveling direction of the motorcycle. 95 and an exhaust muffler 96 disposed on the right side of the rear wheel WR so as to sandwich the rear wheel WR between the power unit P and connected to the downstream end of the exhaust pipe 95.

  4 to 6, the casing 97 of the exhaust muffler 96 is a cylindrical first casing in which a front end and a rear end of a cylindrical body 100 extending in the front-rear direction are closed by hemispherical end caps 101 and 102. A first case 98 and a pair of mutually opposite saddle-like case halves 103 and 104 are joined at a joining surface along the front-rear direction of the motorcycle and joined to the upper part of the first case 98. The second case 99 is formed in a shape bulging upward from the first case 98 in a side view, and the upper outer periphery 99a of the second case 99 substantially corresponds to the outer periphery of the rear wheel WR. Thus, a curved arc shape is formed.

Then, the connecting portions of the case halves 103 and 104 to the upper part of the first case 98 are arranged around the periphery of the first case 98 at the intermediate portion in the front-rear direction of the case halves 103 and 104 as shown in FIG. They are arranged away from each other in the direction (that is, in the vehicle width direction).

  In the cylindrical body 100 of the first case 98, an inner pipe 106 having a plurality of small holes 105 is inserted and fixed coaxially, and a sound absorbing material 107 is filled between the cylindrical body 100 and the inner pipe 106. The Further, the outer periphery of the disk-shaped partition plate 108 is fixed to the inner surface of the inner tube 106 closer to the rear, and the first case 98 and the rear third expansion are formed in the first case 98 by the partition plate 108. It is partitioned into a chamber 111.

  Further, the inner surfaces of the case halves 103 and 104 constituting the second case 99 are welded to a plurality of locations and outer peripheral edges of the inner wall members 112 and 113 having a large number of small holes, so that the case halves 103 and 104 are welded. Between the inner wall members 112 and 113, sound absorbing materials 114 and 115 are filled. Thus, in the second case 98, the second expansion chamber 110 defined by the partial inner surface of the second case 98, the inner wall members 112 and 113 and the upper outer surface of the first case 97 is provided in the first and third. It is formed so as to be located above the expansion chambers 109 and 111.

  The exhaust gas guided by the exhaust pipe 95 is introduced into the first expansion chamber 109 by the first conduit 116, and the first conduit 116 extends in parallel with the axis of the cylindrical body 100 in the first case 98. And a second straight pipe portion 116a, 116c and a curved pipe portion 116b which is bent in a substantially U shape and connects the first and second straight pipe portions 116a, 116c, and is integrally provided. The upstream end of the first straight pipe portion 116 a extending through the front end cap 101 and the lower part of the partition plate 108 and extending in the first expansion chamber 109 in parallel with the axis of the first case 98 is the downstream end of the exhaust pipe 95. The second straight pipe portion 116c penetrates the upper part of the partition plate 108 and extends forward in the first expansion chamber 109, and the downstream end is opened. The curved pipe portion 116b is downstream of the first straight pipe portion 116a. End and second straight pipe Connects between the upstream end of 116c is disposed in the third expansion chamber 111.

  The exhaust gas introduced into the first expansion chamber 109 by the first conduit 116 is guided to the second expansion chamber 110 by the second conduit 117, and the second conduit 117 is an end cap at the rear end of the first case 98. 102 and the partition plate 108 are bent in a substantially C shape, the upstream end of the second conduit 117 is opened to the first expansion chamber 109, and the downstream end of the second conduit 117 is the second expansion chamber 110. Released.

  The exhaust gas introduced into the second expansion chamber 110 by the second conduit 117 is guided to the third expansion chamber 111 by the third conduit 118, and the third conduit 118 is disposed in the third expansion chamber 111. The upper end of the first case 98 penetrates through the end cap 102 at the rear end of the first case 98 such that the upstream end is opened forward and the downstream end is opened to the third expansion chamber 111. To do. The exhaust gas in the third expansion chamber 111 is discharged to the outside through the discharge pipe 119.

  A discharge outer tube 120 penetrating the end cap 102 is fixed to a lower portion of the end cap 102 at the rear end of the first case 98, and the discharge outer tube 120 is protruded from both ends thereof. Both ends of the discharge outer pipe 120 are fixed to the outer surface of the discharge pipe 119 passing through the outer pipe 120 coaxially. That is, the discharge pipe 119 is supported by the end cap 102 of the first case 98 through the discharge outer pipe 120. In addition, a large number of small holes 121 are formed in the discharge pipe 119 at a portion covered with the discharge outer pipe 120, and the sound absorbing material 122 is filled between the discharge pipe 119 and the discharge outer pipe 120.

  Incidentally, a support bracket 123 is provided on the casing 97 of the exhaust muffler 96 so as to protrude forward from the casing 97, and the support bracket 123 is fastened to the engine body 25. Thus, the exhaust muffler 96 is disposed on the right side of the rear wheel WR so that the rear wheel WR is sandwiched between the exhaust muffler 96 and the electric motor 20 constituting a part of the power unit P, and the exhaust muffler 96 is exhausted along the front-rear direction of the vehicle body frame F. The center position C of the muffler 96 is disposed so as to be positioned rearward along the front-rear direction by a distance L as clearly shown in FIG. 2 with respect to the rotation axis of the electric motor 20, that is, the axis of the output shaft 57.

  An air cleaner 89 that is at least part of the intake system 88, an exhaust muffler 96 that forms part of the exhaust system 94, a transmission case 50 in which the electric motor 20 of the power unit P is disposed, and a rear wheel WR Is covered with a common cover 125, and this cover 125 covers the rear fender portion 125a covering the rear wheel WR, the transmission case 50 of the power unit P, and the air cleaner 89 of the intake system 88 so as to cover the rear fender portion 125a. A left cover portion 125b continuously provided on the left side and a muffler protector portion 125c continuously provided on the right side of the rear fender portion 125a so as to cover the exhaust muffler 96 of the exhaust system 94 are integrally formed of synthetic resin. It is formed.

  Moreover, the lower portion of the first expansion chamber 109 provided in the exhaust muffler 96 is disposed above the cover 125 in the vicinity of the lower end opening edge of the muffler protector portion 125c.

  2, the electric motor 20 of the power unit P is configured such that at least a part of the motor case 71 is exposed to the outside from the side surface of the transmission case 50 on one side in the width direction of the body frame F, in this embodiment, on the left side. However, a portion of the motor case 71 exposed from the transmission case 50 travels on the side surface of the cover 125 facing one side in the width direction of the body frame F, that is, the left cover portion 125b of the cover 125. Intake and exhaust side vent holes 126, 127 are provided for cooling with wind.

  An intake-side air hole 126 is provided in the left cover portion 125b of the cover 125 on the front side in the traveling direction of the motorcycle with respect to the electric motor 20, and the left cover portion on the rear side in the traveling direction of the motorcycle with respect to the electric motor 20. An exhaust side air hole 127 is provided at 125b.

  Incidentally, the left cover portion 125b of the cover 125 is provided with a circular opening portion 128 corresponding to the electric motor 20, and a circular cover portion 129 arranged so as to cover the opening portion 128 from the outside. The intake side vent hole 126 is formed between the left end of the left cover part 125b and the cover part 129, and the exhaust side vent hole 127 is formed between the rear end part of the left cover part 125b and the cover part 129.

  Further, the guide is recessed inward so that the dent amount increases toward the rear side, that is, the cover portion 129 side in the left cover portion 125b of the cover 125 on the front side of the motorcycle in the traveling direction of the motorcycle. The concave portion 130 is provided so as to increase in width toward the rear, and the intake-side vent hole 126 is disposed so as to be continuous with the rear end of the guide concave portion 130.

  Referring again to FIG. 1, the front of the head pipe 12 is covered with a front cowl 131 made of synthetic resin, and the steering handle 16 is covered with a handle cover 134 made of synthetic resin except for grips 132 at both ends thereof. . Further, the rear of the head pipe 12 is covered with a center cowl 135 made of synthetic resin, and on both sides of the center cowl 135, a front cowl 131 and leg shields 136 made of synthetic resin connected to the center cowl 135 are arranged.

  Further, a synthetic resin floor panel 137 is fixed on the pair of left and right intermediate frames 14 included in the vehicle body frame F so as to be arranged behind the center cowl 135, and on both sides of the floor panel 137. Are joined to side under cowls 138, 138 made of synthetic resin.

  Further, the rear part of the vehicle body frame F and a part of the engine E are made of synthetic resin and covered with a rear cover 139 supported by the rear frame 15... Established.

  By the way, the floor panel 137 and a part of the pair of left and right side under cowls 138 and 138 coupled to both sides of the floor panel 137 have a rubber mat 141 having a substantially U-shaped cross section opened downward. Is covered by resiliently mounting from above.

  The rubber mat 141 can conceal the fixing portion of the floor panel 137 to the intermediate frame 14 and the joint portion of the side under cowls 138, 138 to the floor panel 137, and the floor panel 137 can be hidden from the intermediate portion. It is possible to prevent mud and water from accumulating in the recesses and holes generated for fixing to the frames 14... And improving the appearance and maintainability. Further, by covering the upper portions of the side under cowls 138, 138 with both sides of the rubber mat 141, the rubber mat 141 can also have a protection function for protecting the side under cowls 138, 138 from being damaged.

  Moreover, when the driver who sits on the riding seat 140 puts his / her foot on the rubber mat 141, grip performance can be improved as compared with placing his / her foot directly on the floor panel 137 made of synthetic resin.

  Next, the operation of this embodiment will be described. An air cleaner 89 that is at least a part of an intake system 88 that is connected to an engine that can apply power to the rear wheels WR, and a part of an exhaust system 94 that is connected to the engine E are configured. The exhaust muffler 96 and the rear wheel WR are covered with a common cover 125, and the electric motor 20 capable of applying power to the rear wheel WR is covered with the cover 125 together with the transmission case 50 in which the electric motor 20 is accommodated. Therefore, not only can the noise generated in the intake system 88 and the exhaust system 94 be prevented from leaking to the outside as much as possible to obtain a soundproof effect, but also the noise generated by the electric motor 20 can be prevented from leaking to the outside as much as possible. Further, the transmission case 50 can be protected by the cover 125 and the appearance design can be enhanced.

  In addition, since the rotational axis of the electric motor 20 is arranged in front of the exhaust muffler 96 along the front-rear direction of the vehicle body frame F, the electric motor 20 is affected by the heat generated by the exhaust muffler 96. Can be avoided as much as possible.

  Further, the electric motor 20 and the exhaust muffler 96 are arranged at positions where the rear wheel WR is sandwiched from both sides, and it is possible to more effectively prevent the influence of the heat generated by the exhaust muffler 96 from reaching the electric motor 20. it can.

  Further, the exhaust muffler 96 is a first expansion chamber 109 into which the exhaust gas from the engine E is introduced, and a second expansion chamber 109 disposed above the first expansion chamber 109 so that the exhaust gas from the first expansion chamber 109 is introduced. Since the lower part of the first expansion chamber 109 is disposed above the lower edge of the right cover portion 125c of the cover 125, the exhaust muffler can be cooled by the traveling wind. Accordingly, the influence of heat from the exhaust muffler 96 to the electric motor 20 can be further reduced.

  In addition, the casing 97 of the exhaust muffler 96 includes a first case 98 that forms the first expansion chamber 109 and a second case 99 that forms the second expansion chamber 110 into which the exhaust gas from the first expansion chamber 109 is introduced. Since the first case 98 forming the first expansion chamber 109 having a high exhaust pressure to be introduced is formed in a cylindrical shape having a high tube rigidity, it is effective to eliminate the outer plate noise without requiring processing that increases the cost. Can be prevented. In addition, the second case 99 forming the second expansion chamber 110 into which the exhaust gas whose exhaust pressure is lower than that of the first expansion chamber 109 is combined with the peripheral portions of the pair of case halves 103 and 104 having a bowl shape. Therefore, it is possible to minimize the response of the outer plate noise in the second case 99, and the capacity can be easily increased. Therefore, the first and second cases 98 and 99 are provided. The capacity of the exhaust muffler 96 as a whole can be easily increased, and the space efficiency can be improved.

  The first case 98 and the second case 99 coupled to the upper portion of the first case 98 are formed in an arc shape in which the upper outer periphery 99a of the second case 99 is bent substantially corresponding to the outer periphery of the rear wheel WR. The muffler protector portion 125c that is disposed on the right side of the rear wheel WR and covers the rear wheel WR from above and the first and second cases 98 and 99 from above is integrally connected to the rear fender 125a. The exhaust muffler 96 can be covered with the muffler protector portion 125c integral with the rear fender portion 125a covering the wheel Wr, and a compact appearance can be obtained.

  Further, in the transmission case 50 of the power unit P, the electric motor 20 is accommodated with at least a part of the motor case 71 included in the electric motor 20 exposed to the outside, and the left side of the cover 125 covering the transmission case 50 is accommodated. The cover portion 125b is provided with intake side and exhaust side vent holes 126, 127 for cooling the portion of the motor case 71 exposed from the transmission case 50 with the traveling wind, so that the traveling wind is guided to the inside of the cover 125. The electric motor 20 can be effectively cooled.

  The intake-side vent hole 126 is provided in the left cover portion 125b of the cover 125 on the front side in the vehicle traveling direction with respect to the electric motor 20, and the exhaust-side vent hole 127 is disposed on the rear side in the vehicle traveling direction with respect to the electric motor 20. Since the traveling wind is introduced into the cover 125 from the intake-side air vent 126 on the front side of the electric motor 20 along the traveling direction of the vehicle and flows through the side surface of the motor case 71, Since the air is discharged to the outside through the exhaust-side vent hole 127 behind the motor 20, the electric motor 20 can be more effectively cooled.

  The left cover 125b of the cover 125 is provided in front of the electric motor 20 in the direction of travel of the vehicle and is provided with a guide recess 130 that is recessed inward so as to increase the amount of recess toward the rear. Since the intake-side vent hole 126 is arranged so as to continue to the rear end of the recess 130, the traveling wind is guided to the intake-side vent hole 126 by the guide recess 130 of the cover 125, and the outer surface of the cover 125. Therefore, the traveling wind can be effectively guided into the cover 125 without causing a protrusion to the cover 125. Therefore, the traveling wind can be effectively guided to the electric motor 20 side while the cover 125 is reduced in size as a whole, and the electric motor 20 is effective. Can be cooled.

  Further, the electric motor 20 is disposed on the left side of the body frame F in the width direction so that at least a part of the motor case 71 is exposed to the outside from the side surface of the transmission case 50, and the intake side and exhaust side vent holes 126 and 127 are provided. Since it is provided on the side surface of the cover 125 facing the left side in the width direction of the body frame F, the air passing through the side surface of the cover 125 on the left side in the width direction of the body frame F is effectively guided into the cover 125 as a running wind. Thus, the electric motor 20 can be cooled more effectively.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. It is.

1 is a side view of a scooter type motorcycle. FIG. FIG. 2 is a sectional view taken along line 2-2 of FIG. FIG. 3 is a sectional view taken along line 3-3 in FIG. 2. It is the rear view which looked at the exhaust muffler from the 4 arrow direction of FIG. FIG. 5 is a sectional view taken along line 5-5 of FIG. FIG. 6 is a sectional view taken along line 6-6 of FIG.

20 ... Electric motor 95 ... Exhaust pipe 96 ... Exhaust muffler
97 ··· Exhaust muffler casing 98 ··· First case 99 ··· Second case 99a · Upper outer periphery 103, 104 · · · Case half body 109 ··· First Expansion chamber 110 ... second expansion chamber
111... Third expansion chamber 125a .. Rear fender portion 125c .. Muffler protector portion
C ... Center position E ... Engine WR ... Rear wheel

Claims (5)

Comprising first expansion chamber leading to an exhaust pipe for guiding exhaust gas from the engine (E) (95) and (109), a second expansion chamber exhaust gas from the first expansion chamber (109) is introduced and the (110) in the exhaust muffler structure in a motorcycle equipped with an exhaust muffler (96),
A casing (97) of the exhaust muffler (96) includes a cylindrical first case (98) that extends in the longitudinal direction of the vehicle body and forms the first expansion chamber (109) therein, and the first case in a side view of the vehicle. A second case (99) formed in a shape bulging upward from the case (98) and forming the second expansion chamber (110) therein;
The second case (99), together with the peripheral portion configured by coupling a pair of case halves facing each other are respectively formed like a bowl (103, 104), at both case halves (103, 104) are respectively coupled to the upper part of the first case (98),
The joint portions of the two case halves (103, 104) to the upper portion of the first case (98) are located at the intermediate portions in the front-rear direction of the two case halves (103, 104). An exhaust muffler structure in a motorcycle, characterized by being spaced apart from each other in the circumferential direction . The casing (97) is disposed on the side of the rear wheel (WR) by forming an upper outer periphery (99a) of the second case (99) in a curved arc shape substantially corresponding to the outer periphery of the rear wheel. The muffler protector portion (125c) covering the first and second cases (98, 99) from above is integrally connected to the rear fender portion (125a) covering the rear wheel (WR) from above. The exhaust muffler structure in a motorcycle according to claim 1. In the first case (98), the first expansion chamber (109) and a third expansion chamber (111) cut off from the first expansion chamber (109) are formed, and the third expansion chamber is formed. The exhaust muffler structure in a motorcycle according to claim 1 or 2, wherein the exhaust gas introduced into the second expansion chamber (110) is guided to (111). The motorcycle according to any one of claims 1 to 3, wherein a lower portion of the first expansion chamber (109) is disposed at a position close to a lower end opening of the muffler protector portion (125c). Exhaust muffler structure. The electric motor (20) capable of applying a driving force to the rear wheel (WR) sandwiches the rear wheel (WR) from the left and right between the motor (20) and the exhaust muffler (96), and It arrange | positions so that the rotating shaft line of this motor (20) may become the front side rather than the front-back direction center position (C) of an exhaust muffler (96), The Claim 1 characterized by the above-mentioned. Exhaust muffler structure for motorcycles.

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