JP6461458B2 - Cooling structure for belt transmission - Google Patents

Description

  The present invention relates to a cooling technique for a belt transmission that introduces cooling air into a belt chamber that houses a V-belt continuously variable transmission mechanism and cools the V-belt continuously variable transmission mechanism.

  In a belt transmission mounted on a motorcycle, particularly a continuously variable transmission mechanism using a V-belt, the temperature in the belt transmission increases due to the generation of frictional heat generated by the sliding contact between the V-belt, the drive pulley, and the driven pulley. If the temperature rises excessively, the durability of the belt may decrease. In order to prevent this, outside air is introduced as cooling air into the belt transmission to prevent temperature rise in the belt transmission.

  The cooling air taken into the belt chamber of the belt transmission device circulates in the belt chamber by the rotation of a cooling fan provided integrally with the drive pulley. At this time, the cooling air in the belt chamber flows from the front to the rear in the vicinity of the belt line on the lower side of the V-belt (belt chamber lower space), and then along the belt chamber rear wall behind the driven pulley. Ascends and flows from the rear to the front in the vicinity of the belt line (belt chamber upper space) on the upper side of the V-belt.

  The cooling air that has flowed through the belt chamber as described above is discharged out of the belt chamber from the discharge port at the top of the belt chamber. At this time, in the cooling structure of the belt transmission device described in Patent Document 1, an air exhaust port is opened in the vertical side wall on the rear wheel side of the transmission case forming the belt chamber, and the air exhaust duct connected to the air exhaust port is interposed therebetween. Configured to be discharged to the outside.

  Further, the cooling structure of the belt transmission described in Patent Document 2 has a first discharge port opened near the rear of the driven pulley in the upper part of the belt chamber, and a second discharge port opened near the front of the driven pulley. Are covered with the main and sub outer covers from above and from the outside, and the cooling air is discharged from below through the discharge passage formed in the outer cover.

JP 2007-263231 A JP 2009-228708 A

  In the invention described in Patent Document 1, since the discharge port is opened in the rear wheel side vertical side wall also serving as the belt case, and is opened in the vertical side wall parallel to the flow of the cooling air, the cooling air Is not smoothly guided to the exhaust port, and the exhaust port is covered with the exhaust duct and exhausted to the outside through the exhaust duct, which makes it difficult to improve the efficiency of cooling air exhaust. There has been a problem in improving the cooling efficiency of the step transmission mechanism.

  Further, in the invention described in Patent Document 2, the first discharge port that opens to the upper part of the belt chamber near the rear of the driven pulley side is formed at the top part of the belt cover at the upper part where the flow of cooling air is reversed. Yes. Since the cooling air in the belt chamber is smoothly discharged from the first discharge port under the action of centrifugal force and inertial force, the centrifugal clutch mechanism is effectively cooled. However, the amount of cooling air discharged from the second outlet tends to be insufficient, and the belt transmission is not necessarily cooled sufficiently. In addition, since the exhaust passage structure is formed by covering the belt case and the belt cover from the outside with the main and sub outer covers to form the exhaust passage structure, the exhaust passage structure becomes large and complicated. There was a problem with large and small degree of freedom.

  The present invention has been made in consideration of the above-described circumstances, and can sufficiently secure the case rigidity to improve the cooling efficiency of the belt transmission, and can increase the design of the belt cover and the degree of freedom in design. It is an object of the present invention to provide a cooling structure for a belt transmission.

  Another object of the present invention is to provide a cooling structure for a belt transmission that can simplify and reduce the weight of the belt cover, reduce the mold cost of the mold, and improve the mold life.

In order to solve the above-described problem, a cooling structure for a belt transmission device according to the present invention includes a drive pulley, a driven pulley, and a V belt continuously wound around the drive pulley and the driven pulley. A transmission mechanism is provided, and this V-belt type continuously variable transmission mechanism is accommodated in a belt chamber formed by a belt case and a belt cover covering the opening of the belt case, and cooling air is introduced into the belt chamber, In the cooling structure of the belt transmission for cooling the V-belt type continuously variable transmission mechanism, an intake port provided in the belt chamber and introducing cooling air from the outside in the vehicle width direction is provided integrally with the drive pulley. A cooling fan for forcibly flowing cooling air in the belt chamber and a belt case side in the belt chamber. A discharge port for discharging the cooled cooling air to the outside of the belt chamber and an exhaust passage communicating with the discharge port are provided between the drive pulley and the driven pulley in the belt chamber and between the V belt and the belt case wall. In the vertical direction, the exhaust duct is provided integrally with the belt case in the belt case, and the exhaust path is a single exhaust duct. The duct has a closed cross-sectional structure, and the cooling air guided from the exhaust port to the exhaust path is discharged downward from the bottom exhaust port.
In order to solve the above-described problems, a cooling structure for a belt transmission according to the present invention includes a drive pulley, a driven pulley, and a V-belt type including a V-belt wound around the drive pulley and the driven pulley. A continuously variable transmission mechanism is provided, and the V-belt type continuously variable transmission mechanism is accommodated in a belt chamber formed by a belt case and a belt cover that covers the opening of the belt case, and cooling air is introduced into the belt chamber. In the cooling structure of the belt transmission that cools the V-belt type continuously variable transmission mechanism, an intake port that is provided in the belt chamber and introduces cooling air from the outside in the vehicle width direction is integrally rotated with the drive pulley. A cooling fan for forcibly flowing cooling air in the belt chamber and a belt case side in the belt chamber. An exhaust port for discharging cooling air that has cooled the room to the outside of the belt chamber, and an exhaust passage communicating with the exhaust port are provided between the drive pulley and the driven pulley in the belt chamber, and the V belt and the belt case. An exhaust duct formed in the vertical direction in the space between the walls, the belt transmission is configured integrally with the engine, and the belt case is integrated from the side of the crankcase of the engine to the vehicle rear side A corner portion is formed at a portion where the rear end portion of the crankcase and the belt case are coupled, and the exhaust duct is coupled to the rear end portion of the crankcase and the belt case. The exhaust duct is disposed at a corner formed by a rear portion of the crankcase and the belt case, and an exhaust port of the exhaust duct is disposed at the rear. Downwardly opening forward of the vehicle center side, it is characterized in that the cooling air guided to the air discharge path from the discharge port was discharged from the exhaust port of the base section thereof downwards.

  In the present invention, an exhaust duct that communicates with the cooling air exhaust port is provided between the drive pulley and the driven pulley in the belt chamber and between the V belt and the belt case. Because it is equipped, the case rigidity of the belt case can be sufficiently secured to improve the cooling efficiency of the belt transmission, the belt cover can be simplified and lightened, and the degree of freedom in design and design can be improved. it can.

Moreover, the cooling air of the belt, since the exhaust port of the street bottom in the vertical direction of the exhaust air passage from the exhaust port can be discharged downward, the radiated sound measures that are exhausted through the exhaust path It can be applied effectively.

The left view which shows embodiment of the scooter type vehicle provided with the cooling structure of the belt transmission which concerns on this invention. The left view of the unit swing type engine mounted in a scooter type vehicle. FIG. 3 is a plan sectional view of the unit swing type engine. The left side view in the state where the cooling structure of the V belt transmission was shown and the belt cover was removed. The left view which shows the flow of the cooling air in the belt chamber which accommodated the V belt transmission. Sectional drawing of the belt case which shows the cooling structure of V belt transmission. Sectional drawing which follows the VII-VII line of FIG.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a right side view showing a scooter type vehicle to which a cooling structure for a belt transmission according to the present invention is applied.

  The scooter type vehicle 10 has a body frame 11 made of, for example, a steel pipe. The body frame 11 has a down tube 13 extending rearwardly and downwardly from a head pipe 12 positioned at the front, and is bent from the vicinity of the lower end thereof to extend rearward in the horizontal direction and terminate. A pair of left and right rear frames 14 rises obliquely rearward and upward from the rear end of the down tube 13, gently bends at a predetermined height, and extends rearwardly upward or rearward. Fuel tanks and storage boxes (both not shown) are supported by the left and right rear frames 14, and a seat 15 is disposed thereon. A swing bracket 16 is provided at the rear end of the down tube 13, and an engine suspension portion 18 of the unit swing type engine 17 is supported on the swing bracket 16 so as to be swingable.

  A front fork 21 that supports the front wheel 20 is pivotally supported on the head pipe 12 together with the handlebar 22 and the headlamp 23, and the front wheel 20 is steered by rotating the handlebar 22.

  On the other hand, in the unit swing type engine 17, an engine 25 and a belt transmission 26 are integrally formed, and a rear wheel 27 as a drive wheel is pivotally supported on the right side of the rear part. In the unit swing type engine 17, the power of the engine 25 is shifted by a belt transmission 26 and transmitted to the rear wheel shaft 30 via the centrifugal clutch mechanism 28 and the deceleration transmission mechanism 29 to drive the rear wheel 27. .

  A rear cushion unit 31 is provided between the rear part of the unit swing type engine 17 and the rear part of the rear frame 14. The unit swing type engine 17 swings in the vertical direction around the swing shaft 19 together with the rear wheel 27 to serve as a swing arm for the rear wheel 27, and the swing is buffered by the rear cushion unit 31.

  FIG. 2 is a left side view of the unit swing type engine 17, and FIG. 3 is a plan sectional view thereof. The engine 25 is, for example, a single-cylinder four-cycle engine, and a cylinder assembly 34 extends from the front portion of the crankcase 33 toward the front of the vehicle so as to tilt forward in a substantially horizontal direction.

  The cylinder assembly 34 includes a cylinder block 35, a cylinder head 36, and a head cover 37 that are sequentially stacked from the crankcase 33 side. In the engine 25, the crankshaft 40 is rotationally driven through the connecting rod and the crankpin by the reciprocating motion of the piston 38 in the cylinder block 35. The crankshaft 40 is rotatably supported by the crankcase 33 via left and right bearings 41.

  Further, the belt transmission 26 is integrally provided from the left side of the crankcase 33 and extends rearward. The crankshaft 40 extends from the crank web 42 to the left and right, a generator 43 is provided at the right extension, and a belt transmission 26, specifically a V belt, is provided at the left extension. A drive pulley 46 of the type continuously variable transmission mechanism 45 is provided.

  On the other hand, the left half of the crankcase 33 is formed integrally with a belt case 50 that also serves as a transmission case. 2 and 3, the belt case 50 constitutes a unit case and is covered with a belt cover 51 from the outside in the vehicle width direction, and a dry belt chamber 52 is formed inside. The belt chamber 52 houses a V-belt continuously variable transmission mechanism 45 that constitutes the belt transmission 26. The belt transmission 26 includes a drive pulley 46 and a driven pulley 47 provided on the crankshaft 40, and a V-belt type continuously variable transmission mechanism 45 having a V-belt 48 wound around the drive pulley 46 and the driven pulley 47. Is configured. The driven pulley 47 is supported by the driven shaft 53 in a floating state, and is clutch-coupled to the driven shaft 53 via the centrifugal clutch mechanism 28.

  A driven shaft 53 that supports the centrifugal clutch mechanism 28 protrudes into the wet mission chamber 54 through the belt case 50 constituting the transmission case 50, and the mission chamber 54 is covered with a mission cover 55 and is liquid-tight. Is done. The mission cover 55 covers the extension of the transmission case 50 from the opposite side of the V-belt type continuously variable transmission mechanism 45, that is, from the inner side in the vehicle width direction. The driven shaft 53 is rotatably supported by the belt case 50 and the mission cover 55 by bearings 56 and 57, and constitutes an input shaft of the deceleration transmission mechanism 29. The speed reduction transmission mechanism 29 is constituted by a multistage, for example, two speed reduction gear train, and its output shaft forms a rear wheel shaft 30. A rear wheel 27 is provided on the rear wheel shaft 30.

  As shown in FIG. 3, the unit swing type engine 17 has a kick starter shaft 58 installed between the crankshaft 40 and the driven shaft 53, and a kick starter lever 59 provided at the outer end thereof. A kick starter mechanism 60 is installed at an intermediate portion of the kick starter shaft 58, and the crankshaft 40 is rotated by operating a kick starter lever 59 when the engine 25 is started. The kick starter lever 59 is biased by a return spring 61 so as to always return to the return position. In FIG. 1, reference numeral 62 denotes a center stand provided at the bottom of the unit swing type engine 17, specifically, below the rear portion of the crankcase 33 of the engine 25. In FIG. 3, reference numeral 64 is a muffler provided at the rear end of the exhaust tube 63.

  By the way, in the unit swing type engine 17, a plurality of cooling fans 65 are integrally formed outside the fixed face 46a of the drive pulley 46 (on the left side in FIG. 3). Due to the rotation of the cooling fan 65, the cooling air from the cooling duct 66 is introduced into the dry belt chamber 52 through the intake port 67 opened on the front side of the belt cover 51. In the belt chamber 52, the temperature rises due to the frictional heat caused by the sliding contact between the V belt 48 and the drive pulley 46 and the driven pulley 47, but this temperature rise is suppressed by the cooling air introduced from the cooling duct 66. Is done.

  The cooling duct 66 is configured integrally with a front outer cover 68 that covers the front side of the belt cover 51 from the outside. The belt transmission 26 that cools the V-belt type continuously variable transmission mechanism 45 and the centrifugal clutch mechanism 28 by cooling air introduced into the belt chamber 52 from the intake passage of the cooling duct 66 through the intake port 67 serving as a suction port. A cooling structure is constructed.

[Unit swing type engine]
In the unit swing type engine 17, the engine 25 and the belt transmission 26 are integrally assembled, and a transmission case 50 extends integrally from the left half of the crankcase 33 of the engine 25 to the vehicle rear side. The transmission case 50 constitutes a belt case 50. The belt case 50 is covered with a belt cover 51 from the outside in the vehicle width direction, and a dry belt chamber 52 is formed inside. The belt transmission device 26 and the centrifugal clutch mechanism 28 are housed in the belt chamber 52, while the transmission case 50 is provided with an extension 50a extending from the belt case 50 toward the rear of the vehicle. The extension 50a of the transmission case 50 is covered with a mission cover 55 from the inside in the vehicle width direction, and a wet mission chamber 54 is formed inside. In the mission chamber 54, a multi-stage type, for example, a decelerating mission mechanism 29 composed of a two-stage decelerating gear train is housed. A rear wheel 27 is provided on the rear wheel shaft 30 on the output side of the deceleration mission mechanism 29.

  The belt transmission 26 includes a V-belt type continuously variable transmission mechanism 45 including a drive pulley 46, a driven pulley 47, and a V-belt 48 in the belt chamber 52, and the driven pulley of the V-belt type conversion transmission mechanism 45. 47 is disposed in the centrifugal clutch mechanism 28 on the outer side in the vehicle width direction. The belt transmission 26 and the centrifugal clutch mechanism 28 are located on the opposite side of the speed reduction transmission mechanism 29 with the transmission case 50 as the belt case 50 as a boundary.

  The belt case 50 is covered with a resin belt cover 51 from the outside in the vehicle width direction, and a front outer cover 68 that covers the intake port 67 from the outside in the vehicle width direction is provided on the front side of the belt cover 51. . When the belt cover 51 is removed from the belt case 50, the cooling fan 65 and the centrifugal clutch mechanism 28 attached to the fixed face 46a of the drive pulley 46 are exposed.

[Cooling structure of belt transmission]
The cooling structure of the belt transmission 26 is such that the frictional heat generated by the sliding contact between the V belt 48 of the V-belt type continuously variable transmission mechanism 45 and the drive pulley 46 and the driven pulley 47, or the frictional heat generated by the centrifugal clutch mechanism 28. The temperature rise in the chamber 52 is introduced into the belt chamber 52 by cooling air, and flows and circulates in the belt chamber 52, and is discharged from the discharge port 69 to suppress the temperature rise in the belt chamber 52. It is to prevent.

  In the cooling structure of the belt transmission 26, a plurality of cooling fans 65 are integrally provided on the fixed face 46 a of the drive pulley 46, and the cooling fan 65 generates cooling air from the cooling duct 66 by rotating the crankshaft 40. The cooling air is introduced into the belt chamber 52 through the intake port (suction port) 67 of the cover 51, and the introduced cooling air is driven to rotate counterclockwise in the belt chamber 52. It is swirled counterclockwise and allowed to flow.

  The flow of the cooling air in the belt chamber 52 that flows by the rotational driving of the cooling fan 65 is guided as shown by an arrow A in FIG. Of the V-belt 48 wound around the drive pulley 46 and the driven pulley 47, in the vicinity of the lower belt line (belt chamber lower space 70), which is the lower belt travel path, flows from the drive pulley 46 toward the driven pulley 47, Then, after flowing upward along the rear wall of the belt chamber 52 located behind the driven pulley 47, the driven pulley is located in the vicinity of the upper belt line (belt chamber upper space 71) which is the upper belt traveling path of the V belt 48. 47 flows toward the drive pulley 46 and is circulated in the belt chamber 52.

  As shown in FIGS. 4 to 7, the discharge port 69 is disposed on the side of the upper belt travel path between the driven pulley 47 and the drive pulley 46 on the vehicle front side of the driven shaft 53. The discharge port 69 opens toward the flow of cooling air flowing in the belt chamber upper space 71 in the belt case 50. The discharge port 69 is opened so as to smoothly capture the cooling air flowing along the belt line on the inner side in the vehicle width direction of the upper belt travel path of the V belt 48.

On the other hand, in the unit swing type engine 17, a dead space is formed between the drive pulley 46 and the driven pulley 47 on the belt chamber 52 side of the belt case 50 constituting the transmission case 50, an intermediate region in the vehicle longitudinal direction. A plurality of longitudinal rib-shaped partition walls 75 are formed in the middle region of the belt case 50 constituting the dead space at a predetermined interval in the vehicle front-rear direction. Of the plurality of longitudinal rib-shaped partition walls 75, the rib-shaped partition wall 75 on the front side of the vehicle is positioned immediately behind the drive pulley 46, and a tunnel-shaped air duct 77 is integrated with the belt case 50 in the rib-shaped partition wall 75. Configured. As shown in the plane sectional view of the unit swing type engine 17 of FIG. 3, a corner is formed at a portion where the rear end portion of the crankcase 33 and the belt case 50 are coupled, and an exhaust duct 77 is formed at the corner. Be placed. In the exhaust duct 77, a vertical exhaust path 79 is formed between the drive pulley 46 and the driven pulley 47 so as to communicate from a discharge port 69 that is a duct inflow port to an exhaust port 78 at the bottom.

  As shown in FIGS. 4 to 6, the air exhaust duct 77 passes through the belt chamber 52 side of the belt case 50 in the vertical direction and is integrally molded together with the case side wall and the rib-like partition wall 75. The top opening of the exhaust duct 77 is closed by a closing cap 80, and an exhaust port 69 is formed at the upper part of the exhaust duct 77 toward the driven pulley 47 on the vehicle rear side on the side of the belt line of the V belt 48. It is open. As shown in FIGS. 5 to 7, the bottom of the exhaust duct 77 has an exhaust port 78 opened downward, preferably toward the tire grounding surface side of the rear wheel 27 or just before the ground. Thus, the cooling air guided to the exhaust duct 77 from the exhaust port 69 that opens on the opposite side of the intake port 67 across the V-belt 48 is longitudinally directed from the upper inlet (exhaust port 69) of the exhaust duct 77. The air is guided into the air exhaust passage 79, flows downward through the air exhaust passage 79, and is exhausted downward from the exhaust port 78 at the bottom.

  Further, in the belt case 50, lateral rib-shaped partition walls 76 partition the belt chamber upper space 71 and the belt chamber lower space 70 in a substantially horizontal direction so as to be orthogonal to the longitudinal rib-shaped partition walls 75 that also serve as reinforcement. Are integrally formed. A bearing boss 82 is provided at the intersection of the longitudinal rib-shaped partition wall 75 and the lateral rib-shaped partition wall 76 on the front side of the vehicle. A kick starter shaft 58 is pivotally supported on the bearing boss 82. The rib-shaped partition wall 76 in the horizontal direction partitions the belt chamber upper space 71 and the belt chamber lower space 70 of the V belt 48 and guides the cooling air to circulate smoothly in the belt chamber 52.

  Further, an attachment boss 83 of the belt case 50 is integrally provided on the case side wall of the belt case 50 on the vehicle rear side of the bearing boss 82 of the belt case 50, that is, on the driven shaft 53 side. The mounting boss 83 is integrally formed on the rib-shaped partition wall 76 in the horizontal direction and serves as a reinforcement. When the belt cover 51 is attached to the belt case 50 from the outside in the vehicle width direction, the belt cover 51 is fixed to the belt case 50 by a plurality of fastening means such as fastening bolts, while the belt cover 51 is centered on the belt cover 51. A mounting boss 83a (see FIG. 3) provided in the section is abutted and joined to the mounting boss 83 of the belt case 50, and is tightened with a fastening bolt or the like to be reinforced.

  In addition, the belt case 50 is configured by integrally forming a plurality of or a plurality of reinforcing ribs 84 in a required shape on the case side wall on the belt chamber 52 side. These reinforcing ribs 84, rib-shaped partition walls 75 and 76 in the vertical and horizontal directions, and the exhaust duct 77 are integrally formed on the belt case 50 and the case side wall, thereby improving the mechanical and physical strength of the belt case 50. The case rigidity is increased.

  In the belt case 50, when the belt transmission device 26 is accommodated in the belt chamber 52, there is a sufficient space where a tunnel-shaped exhaust duct 77 can be installed on the inner side in the vehicle width direction of the belt line of the V belt 48. The exhaust duct 77 provided with the exhaust port 69 is integrally formed by die molding on the case side wall side of the belt chamber 52 of the belt case 50 using this space. Even if the exhaust duct 77 is formed integrally with the belt case 50, sufficient case rigidity can be ensured, as in the case of a conventional belt case in which reinforcing ribs are formed on the case side of the belt case 50. It has been found that even in the case of the exhaust duct 77 having the exhaust port 69, the belt case 50 can be sufficiently molded by forming the exhaust duct 77 integrally by molding and forming a tunnel shape.

  Further, the belt transmission 26 is driven by the rotation of the cooling fan 65 accompanying the rotation of the drive pulley 46, while the cooling air introduced into the belt chamber 52 from the intake port 67 is swung in the belt chamber 52. A cooling structure straddling the belt 48 and entering from the outside in the vehicle width direction to the inside in the vehicle width direction, guided from the exhaust port 69 inside the vehicle width direction to the exhaust duct 77, and exhausted downward from the exhaust port 78 at the bottom of the duct to the ground side. Is adopted. Moreover, the discharge port 69 opens toward the flow of the cooling air so that the cooling air flowing along the belt line of the V belt 48 can be effectively captured. For this reason, the centrifugal clutch mechanism 28 and the V belt type continuously variable transmission mechanism 45 can be effectively cooled. The cooling air whose temperature has risen enters the inside of the belt chamber 52 from the outside in the vehicle width direction across the V-belt 48 and enters the inside of the belt width 52 and exhausts from the discharge port 69 located inside the belt chamber 52 in the vehicle width direction. 77 will guide you smoothly.

  In the cooling structure of the belt transmission 26, the cooling air introduced from the intake port 67 crosses the V belt 48 once and is guided to the discharge port 69. Therefore, the V belt 48 and the pulleys 46 and 47 that are originally intended to be cooled are cooled. The cooling air can be effectively applied to the belt, and the belt cooling efficiency can be improved. Note that the cooling air introduced into the belt chamber 52 from the air inlet 67 easily flows from the cooling fan 65 toward the centrifugal clutch mechanism 28, and a part of the cooling air is centrifuged in a state where the ventilation resistance is low. Since the clutch mechanism 28 is guided and cooled, the centrifugal clutch mechanism 28 can be cooled effectively.

  Further, in the cooling structure of the belt transmission 26, the exhaust duct 77 is configured in a vertical shape in a tunnel shape, so that rainwater, mud, pebbles, and the like dust that has sprung the rear wheel 27 by running of the scooter type vehicle 10 are generated. The flow into the belt transmission 26 can be effectively and reliably prevented.

  Moreover, in the cooling structure of the belt transmission 26, it is not necessary to form the discharge port 69 on the belt cover 51 side, so that the shape and structure of the belt cover 51 can be simplified and the weight can be reduced. The die shape for molding the belt cover 51 can be simplified, and the die cost can be reduced and the die life can be improved.

  Further, the cooled cooling air guided from the outlet 69 to the exhaust duct 77 passes through the exhaust duct 77 and is exhausted from the exhaust outlet 78 to the lower ground side, preferably the rear tire front side. . The cooling air whose temperature has risen after cooling passes through the exhaust duct 77 and is discharged downward from the exhaust port 78. Therefore, the radiated sound (gogging sound) passing through the exhaust duct 77 is reflected on the ground and is reflected on the rider and the side surface. The sound emitted from the engine 25 immediately behind the engine 25 is erased by the tires of the rear wheels 27, so the exhausted sound is not anxious and effective measures against exhaust noise are taken. Can do. Since the discharge port 69 is not discharged to the driver's or passenger's legs, the driver or passenger does not feel uncomfortable.

  In the cooling structure of the belt transmission 26 of the present embodiment, it is not necessary to form a discharge port on the belt cover 51 side, and the cooling air introduced from the intake port 67 is on the belt case on the opposite side across the V belt 48. 50 is led to the exhaust duct 77 from the exhaust port 69 in the interior 50. In addition, since the discharge port 69 opens to the side of the belt line where the flow of the cooling air can be easily captured, the cooling air introduced into the belt chamber 52 swirls and circulates in the belt chamber 52. , And is effectively discharged from the discharge port 69 on the opposite side across the V belt 48. Therefore, the V-belt 48 of the belt transmission 26 can be efficiently and effectively cooled, and the temperature rise of the belt chamber 52 can be effectively suppressed.

  Moreover, since the discharge port 69 is formed at the upper portion of the air exhaust duct 77 in the belt case 50 that does not move like a rotating body, the discharge port 69 is not opened at the top of the belt case 50. Further, the exhaust duct 77 does not need to be provided so as to bulge from the outside of the belt case 50 or the belt cover 51, and is disposed using a dead space between the drive pulley 46 and the driven pulley 67. The cooling structure can be made compact without increasing the size.

  In the cooling structure of the belt transmission 26, an example in which a tunnel-shaped exhaust duct 77 is formed integrally with the belt case 50 and an exhaust port 69 is opened at the upper portion of the exhaust duct 77 is shown. The exhaust duct may be configured separately from the belt case 50.

  Furthermore, although the example which provided the discharge port 69 in the upper part of the exhaust duct 77 in the belt case 50 was shown, the dead space of the vehicle width direction outer side of the extension part 50a of the transmission case (belt case) 50 with this discharge port 69 was shown. A sub-exhaust passage is formed in the reverse flow passage wall on the driven pulley 47 side of the belt case 50 and a sub-exhaust port communicating with the sub-exhaust passage is formed, and a part of the cooling air from the sub-exhaust port is formed. The air may be discharged from the lower exhaust port through the sub air exhaust path.

  DESCRIPTION OF SYMBOLS 10 ... Scooter type vehicle, 11 ... Body frame, 12 ... Head pipe, 13 ... Down tube, 14 ... Rear frame, 15 ... Seat, 16 ... Swing bracket, 17 ... Unit swing type engine, 18 ... Engine suspension part, 19 ... Oscillating shaft, 20 ... front wheel, 21 ... front fork, 22 ... handlebar, 23 ... headlamp, 25 ... engine, 26 ... belt transmission, 27 ... rear wheel, 28 ... centrifugal clutch mechanism, 29 ... deceleration transmission mechanism, DESCRIPTION OF SYMBOLS 30 ... Rear-wheel axle, 31 ... Rear cushion unit, 33 ... Crankcase, 34 ... Cylinder assembly, 35 ... Cylinder block, 36 ... Cylinder head, 37 ... Head cover, 38 ... Piston, 40 ... Crankshaft, 41 ... Bearing, 42 ... Crank web, 43 ... generator, 45 ... V belt type stepless Mechanism: 46 ... Drive pulley, 47 ... Driven pulley, 48 ... V belt, 50 ... Belt case (transmission case), 51 ... Belt cover, 52 ... Belt chamber, 53 ... Driven shaft, 54 ... Mission chamber, 55 ... Mission cover 58 ... kick starter shaft, 59 ... kick starter lever, 60 ... kick starter mechanism, 61 ... return spring, 62 ... center stand, 63 ... exhaust tube, 64 ... muffler, 65 ... cooling fan, 66 ... cooling duct, 67 ... Intake port (suction port), 68 ... Front outer cover, 69 ... Discharge port, 75 ... (Vertical direction) Rib-shaped partition wall, 76 ... (Horizontal direction) Rib-shaped partition wall, 77 ... Exhaust duct, 78 ... Exhaust port, 79 ... exhaust passage, 80 ... blocking cap, 82 ... bearing boss, 83 ... mounting boss, 84 ... reinforcing rib.

Claims (6)

A V-belt continuously variable transmission mechanism including a drive pulley, a driven pulley, and a V-belt wound around the drive pulley and the driven pulley;
This V-belt type continuously variable transmission mechanism is housed in a belt chamber formed by a belt case and a belt cover covering the opening of the belt case,
In the cooling structure of the belt transmission device that introduces cooling air into the belt chamber and cools the V-belt type continuously variable transmission mechanism,
An air inlet provided in the belt chamber for introducing cooling air from the outside in the vehicle width direction;
A cooling fan provided integrally with the drive pulley and forcibly flowing cooling air in the belt chamber;
A discharge port that is provided on the belt case side in the belt chamber and discharges cooling air that has cooled the belt chamber to the outside of the belt chamber;
An exhaust duct communicating with the exhaust port is provided between the drive pulley and the driven pulley in the belt chamber and in the space between the V-belt and the belt case wall, and an exhaust duct formed vertically. ,
The exhaust duct is provided integrally with the belt case in the belt case, and the exhaust path is configured in a closed cross-sectional structure with a single exhaust duct,
A cooling structure for a belt transmission, wherein cooling air guided from the discharge port to the exhaust path is discharged downward from the exhaust port at the bottom. The exhaust passage has an inflow opening opened to a side of an upper belt traveling path of the V belt, and an exhaust port of the exhaust path is opened below a lower belt traveling path of the V belt. The cooling structure of the belt transmission as described in 1. In the rear part of the driven pulley side of the drive pulley, a rib-shaped partition wall in the vertical direction is provided integrally with the case side wall of the belt case,
The cooling structure of the belt transmission according to claim 1, wherein the exhaust duct forming the exhaust path is formed integrally with a longitudinal rib-shaped partition wall and a case side wall of the belt case to form a tunnel shape. While the intake port is formed in the belt cover on the drive pulley side,
2. The belt transmission according to claim 1, wherein the air exhaust path is formed of an air exhaust duct integrally formed in a vertical direction between the drive pulley and the driven pulley on the belt chamber side of the belt case. Cooling structure. The exhaust duct is integrally formed by vertically penetrating the case side wall of the belt case between the drive pulley and the driven pulley,
5. The top of the exhaust duct is covered and closed with a lid cap, and the upper part of the exhaust duct has an inlet opening in the belt chamber, while the bottom of the exhaust duct has an exhaust opening. The cooling structure of the belt transmission as described in 1. A V-belt continuously variable transmission mechanism including a drive pulley, a driven pulley, and a V-belt wound around the drive pulley and the driven pulley;
This V-belt type continuously variable transmission mechanism is housed in a belt chamber formed by a belt case and a belt cover covering the opening of the belt case,
In the cooling structure of the belt transmission device that introduces cooling air into the belt chamber and cools the V-belt type continuously variable transmission mechanism,
An air inlet provided in the belt chamber for introducing cooling air from the outside in the vehicle width direction;
A cooling fan provided integrally with the drive pulley and forcibly flowing cooling air in the belt chamber;
A discharge port that is provided on the belt case side in the belt chamber and discharges cooling air that has cooled the belt chamber to the outside of the belt chamber;
An exhaust duct communicating with the exhaust port is provided between the drive pulley and the driven pulley in the belt chamber and in the space between the V-belt and the belt case wall, and an exhaust duct formed vertically. ,
The belt transmission is configured integrally with an engine,
The belt case is integrally extended from the side of the crankcase of the engine to the vehicle rear side,
A corner portion is formed at a portion where the rear end portion of the crankcase and the belt case are coupled,
The exhaust duct is disposed at the corner where the rear end of the crankcase and the belt case are coupled,
The exhaust port of the exhaust duct opens downward on the vehicle center side in front of the rear wheel,
A cooling structure for a belt transmission, wherein cooling air guided from the discharge port to the exhaust path is discharged downward from the exhaust port at the bottom.

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