JP2009068693A - Engine unit and straddle-type vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine unit with a simple structure which can improve the strength to support a crankshaft and a driven shaft. <P>SOLUTION: A gearless drive mechanism of the engine unit includes a driving side pulley 31 provided on the crankshaft 21, a driven side pulley 41 provided on the driven shaft 27, and a belt 39 looped around the driving side pulley 31 and driven side pulley 41. The gearless drive mechanism is housed in a transmission case. The transmission case has a drive shaft supporting portion 52a supporting an end portion 21d of the crankshaft 21, a driven shaft supporting portion 52b supporting an end portion 27a of the driven shaft 27, and a support column portion 52c bridged between the drive shaft supporting portion 52a and the driven shaft supporting portion 52b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an engine unit that outputs driving force in a straddle-type vehicle.

  Some engine units of straddle-type vehicles (for example, motorcycles) include a belt-type continuously variable transmission. A belt type continuously variable transmission is generally wound around a driving pulley provided on a driving shaft, a driven pulley provided on a driven shaft, and a driving pulley and a driven pulley. And a belt for transmitting a driving force from the driving pulley to the driven pulley.

Conventionally, in an engine unit including such a belt-type continuously variable transmission, there is an engine unit that supports an end of a drive shaft and an end of a driven shaft with a case that houses the continuously variable transmission (for example, Patent Document 1).
Japanese Patent Laid-Open No. 2002-19669

  However, when the belt is tightly wound so that there is no transmission loss of the driving force between the driving pulley and the driven pulley, a force in the direction in which the driving shaft and the driven shaft are brought close to each other is applied from the belt. The drive shaft and the driven shaft may be slightly bent. In the conventional engine unit described above, in order to prevent such bending, it is necessary to increase the rigidity of the entire case that supports these shafts, which may reduce the productivity of the engine unit.

  The present invention has been made in view of the above problems, and one of its purposes is an engine unit and a straddle-type vehicle capable of improving the support strength of the drive shaft and the driven shaft with a simple structure. Is to provide.

  In order to solve the above-described problems, an engine unit according to the present invention includes a drive shaft, a driven shaft disposed away from the drive shaft, a drive pulley provided on the drive shaft, and the driven shaft. And a continuously variable transmission including a belt wound around the driven pulley and the driven pulley, and a case for housing the continuously variable transmission. The case includes a drive shaft support portion that supports an end portion of the drive shaft, a driven shaft support portion that supports an end portion of the driven shaft, and the drive shaft support portion and the driven shaft support portion. And a strut portion spanned between them.

  In order to solve the above problems, a saddle-ride type vehicle according to the present invention includes the engine unit.

  According to the present invention, since the support column is provided on the case that supports the drive shaft and the driven shaft, the support strength of the drive shaft and the driven shaft can be improved with a simple structure, and the bending of these shafts can be prevented. it can. The straddle-type vehicle is, for example, a motorcycle (including a scooter), a four-wheel buggy, a snowmobile, or the like.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side view of a motorcycle 1 including an engine unit 10 which is an example of an embodiment of the present invention. FIG. 2 is a side view of the engine unit 10, and FIG. 3 is a cross-sectional view of the engine unit 10. FIG. 2 shows the vehicle body frame 2 together with the engine unit 10.

  As shown in FIGS. 1 and 2, the motorcycle 1 includes an engine unit 10 and a body frame 2. As shown in FIG. 2, the vehicle body frame 2 includes a steering head 2a, a main frame 2b, a seat rail 2c, a stay 2d, and a bracket 2e. As shown in FIG. 1, the steering head 2 a is provided at the front end of the vehicle body frame 2 and rotatably supports a steering shaft 6 that rotates together with the handle 5. A front fork 7 is connected to the lower end portion of the steering shaft 6, and the lower end portion of the front fork 7 supports the front wheel 3.

  As shown in FIG. 2, the front end portion of the main frame 2b is connected to the steering head 2a. The main frame 2 b extends obliquely downward from its front end toward the rear of the vehicle body, and its rear end (lower end) 2 i is positioned in front of the rear wheel 4. A front end 2j of the seat rail 2c is connected to the middle of the main frame 2b. The seat rail 2c extends obliquely upward from the front end 2j toward the rear of the vehicle body. A storage case 8 and a seat 9 are disposed above the seat rail 2c, and the seat rail 2c supports them (see FIG. 1). A front end portion of the stay 2d is connected to the rear end portion 2i of the main frame 2b, the stay 2d extends obliquely upward from the front end portion, and an upper end portion of the stay 2d is connected to the middle of the seat rail 2c (FIG. 1). reference).

  As shown in FIG. 2, the bracket 2e is a plate-like member extending downward, and its upper edge is joined to the rear end 2i of the main frame 2b. The bracket 2e has a support portion 2g for supporting the pivot shaft 12 at its upper portion (see FIG. 2). As shown in FIG. 1, the front end portion of the rear arm 11 is attached to the pivot shaft 12. The rear arm 11 extends rearward (the direction opposite to the direction indicated by Fr in FIG. 1), and the rear end portion supports the axle of the rear wheel 4. The rear arm 11 swings up and down with the rear wheel 4 with the pivot shaft 12 as a fulcrum, and swings independently with respect to the engine unit 10.

  As shown in FIG. 2, the bracket 2e has a mounted portion 2f to which the engine unit 10 is mounted on the front side of the lower end portion thereof. Further, brackets 2L and 2m protruding downward are joined in the middle of the main frame 2b. The upper upper wall of the crankcase 60 included in the engine unit 10 is attached to the bracket 2L, the upper rear wall of the crankcase 60 is attached to the bracket 2m, and the lower part of the crankcase 60 is attached to the bracket 2e. It is attached to the part 2f. As a result, the engine unit 10 is supported by the vehicle body frame 2.

  As shown in FIG. 2, the engine unit 10 is disposed below the rear portion of the main frame 2 b and in front of the rear wheel 4. As shown in FIG. 3, the engine unit 10 includes an engine 20, a continuously variable transmission 30, a clutch 80, a crankcase 60, and a transmission case 50 that houses the continuously variable transmission 30. The engine unit 10 further includes an intake duct 71 for sending outside air into the transmission case 50 and an exhaust duct 74 for discharging the air in the transmission case 50 (see FIG. 2). As shown in FIG. 2, the engine unit 10 includes a cover 14 that covers the transmission case 50 from the side. In FIG. 3, the cover 14 is not shown.

  As shown in FIG. 3, the engine 20 includes a crankshaft 21, a cylinder 22, and a piston 23. The cylinder 22 is disposed in a posture slightly inclined upward in front of the crankcase 60 (direction indicated by Fr in FIG. 3). The piston 23 reciprocates in the cylinder 22 as a mixture of fuel and air sent into the cylinder 22 from an unillustrated intake port burns. The piston 23 is connected to a crankpin 25 provided on the crankshaft 21 via a connecting rod 24. The reciprocating motion of the piston 23 is converted into a rotational motion by the crankshaft 21 and output to the downstream side of the driving force transmission path.

  The crankshaft 21 is disposed in the crankcase 60 so as to extend in the vehicle width direction (direction indicated by W in FIG. 3). The crankshaft 21 has a right shaft portion 21a, a left shaft portion 21b, and a pair of crank arms 21c and 21c. The crank arms 21c and 21c extend radially from the bases of the right shaft portion 21a and the left shaft portion 21b (in a direction perpendicular to the center line of the shaft) and rotatably support the crank pin 25.

  A base portion of the left shaft portion 21 b is supported by the crankcase 60 via a bearing 69. The left shaft portion 21b extends outward from the base portion in the vehicle width direction. A generator (not shown) is provided on the left shaft 21b.

  A base portion of the right shaft portion 21 a is supported by the crankcase 60 via a bearing 68. The right shaft portion 21a extends outward from the base portion in the vehicle width direction. A driving pulley 31 of the continuously variable transmission 30 is provided on the right shaft portion 21a. An end 21d of the right shaft 21a is supported by the transmission case 50. The transmission case 50 will be described in detail later.

  The engine unit 10 has a driven shaft 27 and an output shaft 29 disposed on the center line of the driven shaft 27 at a position separated rearward from the crankshaft 21. The driven shaft 27 is arranged to extend in the vehicle width direction. On the driven shaft 27, a driven pulley 41 of the continuously variable transmission 30 and a clutch 80 are provided. The driven pulley 41 is located behind the driving pulley 31, and the clutch 80 is disposed inside the driven pulley 41 in the vehicle width direction.

  An end 27 a on the outer side (right side) of the driven shaft 27 in the vehicle width direction is supported by the transmission case 50. The transmission case 50 will be described in detail later.

  A bearing 65 and a bearing 63 located on the outer side (end side) of the bearing 65 are fitted to the end 27 b on the inner side (left side) of the driven shaft 27 in the vehicle width direction. The outer ring of the bearing 65 is supported by the crankcase 60, and the crankcase 60 supports the end portion 27 b of the driven shaft 27 via the bearing 65. An output shaft 29 is fitted on the outer ring of the bearing 63, and the bearing 63 supports the output shaft 29. A central portion 29 a of the output shaft 29 is supported by the crankcase 60 via a bearing 62.

  A bearing 66 is fitted in the central portion 27 c of the driven shaft 27. The outer ring of the bearing 66 is supported by a partition member 64 fixed to the crankcase 60, and the crankcase 60 supports the central portion of the driven shaft 27 via the partition member 64 and the bearing 66. The partition member 64 is located between the clutch 80 and the driven pulley 41 and closes the clutch chamber 60a in the crankcase 60. A clutch 80 is disposed in the clutch chamber 60a.

  The continuously variable transmission 30 is a belt-type continuously variable transmission, and includes the driving pulley 31 and the driven pulley 41 as described above. The continuously variable transmission 30 includes a belt 39 that is wound around the driving pulley 31 and the driven pulley 41 and transmits torque from the driving pulley 31 to the driven pulley 41.

  FIG. 4 is a cross-sectional view of the continuously variable transmission 30 and the clutch 80. As described above, the driving pulley 31 is provided on the right shaft portion 21 a of the crankshaft 21. The driving pulley 31 has a fixed sheave 32, a movable sheave 33, and a plate 35. The fixed sheave 32 and the plate 35 are restricted from moving in the axial direction, and the movable sheave 33 is allowed to move in the axial direction between the fixed sheave 32 and the plate 35. The movable sheave 33 faces the fixed sheave 32 in the axial direction, and the front side of the belt 39 is wound around these.

  Between the movable sheave 33 and the plate 35, a weight roller 34 that moves in the radial direction by centrifugal force is disposed. When the crankshaft 21 rotates, the weight roller 34 moves radially outward and presses the movable sheave 33 toward the fixed sheave 32 side. The belt 39 is pushed by the movable sheave 33 and moves forward, and the diameter of the portion of the belt 39 wound around the driving pulley 31 is increased, so that the reduction ratio is reduced.

  Note that collars 37a, 37b, and 37c are fitted to the right shaft portion 21a. An annular member 54 and a nut 55, which will be described later, are fitted to the end portion 21d of the right shaft portion 21a from the outside of the collar 37a, thereby restricting the axial movement of the collars 37a, 37b, and 37c. The axial movement of the fixed sheave 32 sandwiched between the collar 37a and the collar 37b and the plate 35 sandwiched between the collar 37b and the collar 37c is also restricted.

  The drive pulley 31 has a fan 36 for introducing outside air into the transmission case 50. In the example shown in FIG. 4, the fan 36 is formed so as to rise from the fixed sheave 32 to the outside in the vehicle width direction (the direction indicated by W in FIG. 4). As the fan 36 rotates together with the fixed sheave 32, outside air is introduced from the intake duct 71, air in the transmission case 50 is sent to the driven pulley 41 side, and is discharged from the exhaust duct 74 (see FIG. 2). ).

  The driven pulley 41 is provided on the driven shaft 27 and rotates together with the driven shaft 27 by the torque transmitted through the belt 39. The driven pulley 41 includes a fixed sheave 42 in which movement in the axial direction is restricted, a movable sheave 43 that is movable in the axial direction, and a collar 46 that restricts movement in the axial direction of the fixed sheave 42. . A collar 48, a fixed sheave 42, and a collar 46 are fitted to the driven shaft 27 in this order. These are sandwiched between a bearing 66, an annular member 57 and a nut 59 described later, and the movement in the axial direction is restricted. The collar 46 and the fixed sheave 42 are coupled to the driven shaft 27 by a spline, and these rotate integrally.

  A disc-shaped spring support member 45 that rotates together with the collar 46 is fitted to the outer end of the collar 46 in the vehicle width direction. The spring support member 45 includes an inner peripheral portion 45a, a cylindrical portion 45b that rises in the axial direction from the edge of the inner peripheral portion 45a, and an outer peripheral portion 45c that expands in the radial direction from the edge of the cylindrical portion 45b.

  The movable sheave 43 has a sheave body 43 a that extends in the radial direction of the driven shaft 27 and a cylindrical boss portion 43 b that is fitted to the collar 46. A spring 44 for urging the movable sheave 43 toward the fixed sheave 42 is fitted to the boss portion 43b. The spring 44 is supported on the fixed sheave 42 side by an inner peripheral portion 45 a of a spring support member 45.

  The boss portion 43b is formed with guide grooves 43c, 43c extending in the axial direction. Inside the guide grooves 43c and 43c, a key 47 whose tip is inserted into the collar 46 is disposed. Thereby, the rotation of the movable sheave 43 is transmitted to the collar 46 through the key 47, and the movable sheave 43 is guided by the key 47 and moves in the axial direction.

  The rear side of the belt 39 is wound around the sheave body 43 a of the movable sheave 43 and the fixed sheave 42. When the movable sheave 33 pushes the belt 39 forward in the driving pulley 31, the movable sheave 43 moves in the direction away from the fixed sheave 42 against the urging force of the spring 44 in the driven pulley 41. As a result, the diameter of the portion of the driven pulley 41 around which the belt 39 is wound is reduced, and the reduction ratio is increased.

  The clutch 80 transmits or blocks the torque transmitted from the driven shaft 27 to the downstream side (rear wheel 4 side) of the driving force transmission path. In the example described here, the clutch 80 includes a clutch outer 82 that rotates together with the driven shaft 27, and a clutch inner 81 that idles with respect to the driven shaft 27. The clutch 80 is a multi-plate clutch, and has a plurality of disk-shaped friction plates 83 and a plurality of clutch plates 84 arranged so as to surround the clutch inner 81 inside the clutch outer 82. On the driven shaft 27, a gear 26 that idles with respect to the driven shaft 27 is provided, and the clutch inner 81 rotates together with the gear 26.

  On the outer peripheral edge of the friction plate 83, a protruding portion 83a protruding in the radial direction is formed. The protrusion 83a is fitted in a guide groove 82c formed in the clutch outer 82 and extending in the axial direction. As a result, the friction plate 83 can move in the axial direction and rotates around the driven shaft 27 together with the clutch outer 82. The inner peripheral surface of the clutch inner 81 is engaged with the gear 26. On the inner peripheral edge of the clutch plate 84, a protrusion 84a that protrudes inward in the radial direction is formed. The protrusion 84 a is fitted in a guide groove 81 b formed on the outer peripheral surface of the clutch inner 81 and extending in the axial direction. As a result, the clutch plate 84 can move in the axial direction and rotates together with the clutch inner 81.

  The plurality of friction plates 83 and the plurality of clutch plates 84 are alternately arranged, and these are pressed against each other to interlock with each other, whereby torque is transmitted from the friction plates 83 to the clutch plates 84. In the example shown in FIG. 4, the clutch 80 is an automatic clutch, and the connection or disconnection of the clutch 80 is automatically performed according to the rotational speed of the driven shaft 27. Specifically, the clutch 80 includes a weight roller 86 that rotates around the driven shaft 27 together with the clutch outer 82, and a diaphragm spring 85 that biases the friction plate 83 in the axial direction. A plurality of friction plates 83 and a plurality of clutch plates 84 are disposed between the weight roller 86 and the diaphragm spring 85. When the clutch outer 82 rotates, the weight roller 86 moves in the radial direction by centrifugal force and presses the friction plate 83 against the clutch plate 84. As a result, the clutch 80 is in a connected state. Further, when the rotational speed of the driven shaft 27 decreases, the weight roller 86 returns to the inside in the radial direction (the driven shaft 27 side), the friction plate 83 is separated from the clutch plate 84, and the clutch 80 is in a disconnected state.

  The rotation of the crankshaft 21 is decelerated by the continuously variable transmission 30 and transmitted to the driven shaft 27. When the clutch 80 is in the connected state, the rotation of the driven shaft 27 is transmitted to the gear 26 that can idle with respect to the driven shaft 27 via the clutch 80. As shown in FIG. 3, the gear 26 meshes with a gear 28 a of an intermediate shaft 28 disposed in front of the driven shaft 27. Further, a gear 28 b is formed on the intermediate shaft 28, and the gear 28 b meshes with a gear 29 b formed on the output shaft 29. As a result, the rotation of the gear 26 is transmitted to the output shaft 29 via the intermediate shaft 28. On the output shaft 29, a sprocket 29c around which a chain (not shown) is wound is provided. The chain is also wound around a sprocket (not shown) that rotates with the rear wheel 4, and the rotation of the output shaft 29 is transmitted to the rear wheel 4 through the chain.

  Here, the transmission case 50 will be described in detail. FIG. 5 is a side view of the transmission case 50, and FIG. 6 is a plan view of the transmission case 50. As shown in FIG. 4, the transmission case 50 includes a case main body 51 that houses the continuously variable transmission 30 therein, and is attached to the case main body 51, and an end 21 d of the crankshaft 21 and an end of the driven shaft 27. 27a, and a support member 52 that supports 27a.

  The case body 51 has a hook shape that opens inward in the vehicle width direction (center side in the vehicle width direction), and an edge 51 h of the case body 51 is attached to an edge 60 b of the crankcase 60 on the outer side in the vehicle width direction. A driving pulley 31 is disposed inside the front portion of the case body 51, and a driven pulley 41 is disposed inside the rear portion. As shown in FIGS. 4 and 6, the case main body 51 has bulging portions 51 a and 51 b bulging outward in the vehicle width direction at the front and rear portions thereof. The case main body 51 has an intake port 51c for taking in outside air and an exhaust port 51d for discharging the air in the transmission case 50.

  As shown in FIGS. 3 and 5, the air inlet 51 c is formed so as to protrude forward from the bulging portion 51 a. An intake duct 71 extending obliquely upward is connected to the intake port 51c, and an air cleaner 72 is attached to the tip of the intake duct 71 (see FIG. 2). As shown in FIG. 2, a tip duct 73 protruding upward is attached to the upper portion of the air cleaner 72. The outside air taken in from the end duct 73 by the rotation of the fan 36 provided in the driving pulley 31 is purified by the air cleaner 72 and then sent to the transmission case 50 through the intake duct 71.

  As shown in FIG. 5, the exhaust port 51 d is formed so as to protrude obliquely upward from the rear portion of the case body 51. As shown in FIG. 2, an exhaust duct 74 is connected to the exhaust port 51d. Air in the transmission case 50 is pushed out by the rotation of the fan 36, passes through the exhaust duct 74, and is released under the storage case 8.

  As shown in FIG. 4, the wall of the bulging portion 51a is formed with an opening 51e that exposes the end portion 21d of the crankshaft 21 in the axial direction. The end portion 21d and the bearing 53 that rotatably supports the end portion 21d are located outside the opening 51e and are supported by the support member 52. An opening 51f that exposes the end 27a of the driven shaft 27 in the axial direction is formed in the wall of the bulging portion 51b. The end portion 27a and the bearing 56 that rotatably supports the end portion 27a are located outside the opening 51f and are supported by the support member 52. The spring support member 45 of the driven pulley 41 is located inside the bulging portion 51b.

  7 is a cross-sectional view taken along line VII-VII in FIG. As shown in FIGS. 5 and 7, the support member 52 is a member that is long in the front-rear direction of the vehicle body, and has a drive shaft support portion 52a at the front portion thereof and a driven shaft support portion 52b at the rear portion thereof. ing. Further, the support member 52 has a support column portion 52c that spans between and extends between the drive shaft support portion 52a and the driven shaft support portion 52b.

  The support member 52 is attached to the case body 51 from the outside in the vehicle width direction so as to close the openings 51e and 51f of the case body 51. In this example, as shown in FIG. 6, the support member 52 includes radial directions (a direction orthogonal to the center line of the crankshaft 21 and the driven shaft 27) from the drive shaft support portion 52 a and the driven shaft support portion 52 b. A plurality (six in this case) of mounting portions 52k projecting in the direction perpendicular to the center line of the first mounting portion 52k are provided. The attachment portion 52k is attached to the outer wall of the case main body 51 with, for example, a bolt.

  The drive shaft support portion 52a rotatably supports the end portion 21d of the crankshaft 21. As shown in FIG. 7, a circular recess is formed inside the drive shaft support 52a, and a bearing 53 is fitted in the recess. An annular member 54 that rotates together with the inner ring is disposed inside the inner ring of the bearing 53. The annular member 54 is fitted to the end 21 d of the crankshaft 21 and rotates together with the crankshaft 21. Thus, the drive shaft support portion 52a supports the end portion 21d of the crankshaft 21 through the bearing 53 and the annular member 54.

  As shown in FIG. 4, the drive shaft support portion 52 a is attached to the outer wall of the bulging portion 51 a of the case body 51 and is separated from the fan 36 provided in the fixed sheave 32 in the axial direction. An intake port 51c is located between the fan 36 and the drive shaft support 52a in the vehicle width direction.

  At the edge of the opening 51e of the case main body 51 shown in FIG. 7, a retaining portion 51g for preventing the bearing 53 from falling off inward in the vehicle width direction is provided. FIG. 8 is a side view of the case body 51. In the example described here, as shown in FIGS. 8 and 7, the retaining portion 51g protrudes inward (center side of the opening) from the edge of the opening 51e, and the bearing 53 is between the driving shaft support portion 52a. The outer ring 53a is sandwiched. In this example, the retaining portion 51g is formed by projecting a part of the edge of the opening 51e inward. However, the inner diameter of the opening 51e may be smaller than the outer diameter of the bearing 53, and the edge of the opening 51e may be used as a retaining portion.

  As shown in FIG. 7, the annular member 54 is formed with a recess 54 a that is recessed in the axial direction of the crankshaft 21. A nut 55 is fitted to the end 21 d of the crankshaft 21 from the outside of the annular member 54. The nut 55 is accommodated in the axial direction in the recess 54 a of the annular member 54. As a result, the end surface 55 a of the nut 55 is located on the same plane as the end surface 53 b of the bearing 53. An oil groove 54b extending in the circumferential direction is formed on the outer peripheral surface of the annular member 54, and oil is injected into the oil groove 54b, whereby the outer peripheral surface of the annular member 54 and the inner peripheral surface of the bearing 53 are formed. And are lubricated.

  As shown in FIGS. 5 and 7, a circular opening 52m for exposing the end 21d of the crankshaft 21 and the nut 55 in the axial direction is formed on the outer wall of the drive shaft support 52a in the vehicle width direction. Has been. A circular lid 91 is also fitted to the edge of the opening 52m to close the opening 52m. The lid 91 is removable, and the end 21d of the crankshaft 21 and the nut 55 are exposed by removing the lid 91. For example, when performing an operation of positioning the piston 23 at the top dead center, a tool for holding the end 21d of the crankshaft 21 and the nut 55 and rotating the crankshaft 21 is inserted into the opening 52m. be able to. As shown in FIG. 7, a gap is provided between the outer peripheral surface 55b of the nut 55 and the inner peripheral surface of the recess 54a of the annular member 54 surrounding the outer peripheral surface 55b.

  The driven shaft support portion 52b is located in the direction (here, rearward) in which the belt 39 extends with respect to the drive shaft support portion 52a. The driven shaft support portion 52b rotatably supports the end portion 27a of the driven shaft 27. Specifically, as shown in FIG. 7, a circular concave portion is formed inside the driven shaft support portion 52b similarly to the drive shaft support portion 52a, and a bearing 56 is fitted into the concave portion. . An annular member 57 that rotates together with the inner ring is disposed inside the inner ring of the bearing 56. The annular member 57 is fitted to the end 27 a of the driven shaft 27 and rotates together with the driven shaft 27. Accordingly, the driven shaft support portion 52 b supports the end portion 27 a of the driven shaft 27 via the bearing 56 and the annular member 57.

  An annular member 58 that prevents the bearing 56 from dropping inward in the vehicle width direction is attached to the edge of the opening 51 f of the case body 51. In this example, the inner diameter R of the annular member 58 is smaller than the outer diameter of the bearing 56 as shown in FIG. 8 (see FIG. 7). The annular member 58 has, on its inner periphery, a retaining portion 58a that sandwiches the outer ring 56a of the bearing 56 with the driven shaft support portion 52b. The annular member 58 is disposed between the edge of the opening 51f of the case body 51 and the driven shaft support portion 52b, and is attached to the edge of the opening 51f with, for example, a bolt.

  As with the annular member 54, the annular member 57 has a recess 57 a that is recessed in the axial direction of the driven shaft 27. A nut 59 is fitted to the end 27 a of the driven shaft 27 from the outside of the annular member 57. The nut 59 is housed in the recess 57 a of the annular member 57 in the axial direction. As a result, the end surface 59 a of the nut 59 is located on the same plane as the end surface 56 b of the bearing 56. Further, as shown in FIG. 6, the side surface 52d on the outer side in the vehicle width direction of the drive shaft support portion 52a and the side surface 52e on the outer side in the vehicle width direction of the driven shaft support portion 52b are flush with each other. Furthermore, in this example, the side surface 52L of the support column 52c is also flush with the side surface 52d and the side surface 52e.

  As described above, the support member 52 has the column portion 52c that spans between the drive shaft support portion 52a and the driven shaft support portion 52b. As shown in FIG. 7, the support column 52 c is located between the bearing 53 and the bearing 56. Further, as shown in FIG. 5, the support column 52c has a pair of upper and lower support columns 52f and a lower support column 52g. The upper column portion 52f and the lower column portion 52g are formed such that their distances are closest to each other at the central portions 52h and 52i. The central portions 52h and 52i are connected by a reinforcing portion 52j extending in the vertical direction.

  Note that the support column portion 52c is not limited to the one including the upper and lower pair of upper support column portions 52f and the lower support column portion 52g. For example, on the plane including the center line of the crankshaft 21 and the center line of the driven shaft 27. The shaft may be extended from the drive shaft support portion 52a side to the driven shaft support portion 52b side.

  As described above, the front side of the belt 39 is wound around the driving pulley 31 and the rear side of the belt 39 is wound around the driven pulley 41. For this reason, if the belt 39 is tightly wound around two pulleys in order to reduce transmission loss, there is a risk that a force that bends them is applied to the right shaft portion 21a of the crankshaft 21 and the driven shaft 27. In the engine unit 10, a support column 52c is formed between the drive shaft support 52a and the driven shaft support 52b. As a result, the support strength of the crankshaft 21 and the driven shaft 27 can be increased, and bending of these shafts can be prevented.

  Further, the transmission case 50 houses a support member 52 having a drive shaft support portion 52a, a driven shaft support portion 52b, and a column portion 52c, the continuously variable transmission 30, and a case main body to which the support member 52 is attached. 51. Thus, in the engine unit 10, the support member 52 is a separate member from the case main body 51. For example, by making the material of the support member 52 more rigid than the material of the case main body 51, The support strength of the shaft can be increased. In addition, after attaching the case main body 51 to the crankcase 60, the support member 52 is attached to the case main body 51 so that the bearing 53 and the bearing 56 are fitted to the drive shaft support portion 52a and the driven shaft support portion 52b. Thus, for example, the assembling work of the transmission case is facilitated as compared with the case where the portion supporting the end portion of the shaft and the case body are integrally molded.

  Further, the end 21d of the crankshaft 21 is exposed in the axial direction from an opening 51e formed in the case main body 51, and is rotatably supported by a bearing 53 disposed outside the opening 51e in the axial direction. Further, at the periphery of the opening 51e, a retaining portion 51g that sandwiches the bearing 53 with the support member 52 is provided. Further, the end 27a of the driven shaft 27 is exposed in the axial direction from an opening 51f formed in the case body 51, and is rotatably supported by a bearing 56 disposed outside the opening 51f in the axial direction. A retaining portion 58 a that sandwiches the bearing 56 with the support member 52 is provided at the periphery of the opening 51 f. This can prevent the bearings 53 and 56 from falling off.

  Further, in the engine unit 10, the retaining portion 51g and the retaining portion 58a sandwich the outer rings of the bearings 53 and 56. As a result, the crankshaft 21 and the driven shaft 27 supported by the bearings 53 and 56 can be smoothly rotated. Further, the retaining portion 51g protrudes from the periphery of the opening 51e of the case body 51 toward the inside of the opening 51e. Thereby, the retaining portion 51g can be integrally formed with the case body 51, and the productivity of the engine unit 10 can be improved. Further, since the annular member 58 having the retaining portion 58a is a member attached to the case main body 51, the case main body 51 itself can be easily formed.

  Further, the drive shaft support portion 52a is located in the direction in which the belt 39 extends with respect to the driven shaft support portion 52b. Therefore, the support strength of the crankshaft 21 and the driven shaft 27 can be increased.

  Further, the side surface 52d of the drive shaft support portion 52a, the side surface 52e of the driven shaft support portion 52b, and the side surface 52L of the support column portion 52c are flush with each other. Therefore, the increase in the vehicle width can be suppressed as compared with the case where the side surface 52d and the side surface 52e are expanded outward in the vehicle width direction and the nuts 55 and 59 are covered from the outside.

  Further, the engine unit 10 includes a bearing 53 for rotatably holding the end 21d of the crankshaft 21, an annular member 54 that is disposed inside the inner ring of the bearing 53 and is fitted to the end 21d, and an annular member 54. And a nut 55 fitted to the end 21d from the outside in the axial direction. The annular member 54 is formed with a concave portion 54a that is recessed in the axial direction, and the nut 55 is fitted into the end portion 21d and accommodated in the concave portion 54a of the annular member 54. The engine unit 10 includes a bearing 56 for rotatably holding the end portion 27a of the driven shaft 27, an annular member 57 that is disposed inside the inner ring of the bearing 56 and is fitted to the end portion 27a, And a nut 59 fitted to the end portion 27a from the outer side in the axial direction than the member 57. The annular member 57 is formed with a concave portion 57a that is recessed in the axial direction, and the nut 59 is fitted into the end portion 27a and accommodated in the concave portion 57a of the annular member 57. Thereby, the crankshaft 21 and the driven shaft 27 can be shortened by the amount of the nuts 55 and 59 accommodated in the annular members 54 and 57, and an increase in the vehicle width can be suppressed.

  The transmission case 50 is formed with an intake port 51c for introducing outside air into the case. The fan 36 rotates on the crankshaft 21 together with the crankshaft 21 and introduces outside air from the intake port 51c. Is provided. The drive shaft support portion 52a is disposed away from the fan 36 in the axial direction of the crankshaft 21, and the intake port 51c is located between the fan 36 and the drive shaft support portion 52a in the axial direction. For this reason, the continuously variable transmission 30 can be cooled by outside air. Further, the intake port 51c is located between the fan 36 and the drive shaft support portion 52a, and the air flow from the intake port 51c to the fan 36 is not hindered by the drive shaft support portion 52a. Can be achieved.

  The drive shaft support 52a is formed with an opening 52m through which the end 21d of the crankshaft 21 is exposed while the drive shaft support 52a supports the crankshaft 21. Thus, the crankshaft 21 can be rotated in a state where the crankshaft 21 is supported by the support member 52. For example, the crankshaft with respect to the camshaft that drives the valve that opens and closes the intake port or the exhaust port of the engine 20 The rotation angle of the shaft 21 can be adjusted.

  The present invention is not limited to the engine unit 10 described above, and various modifications can be made. For example, in the above description, the side surface 52L of the support column portion 52c, the side surface 52d of the drive shaft support portion 52a, and the side surface 52e of the driven shaft support portion 52b are flush with each other. However, the side surface 52d of the drive shaft support portion 52a and the side surface 52e of the driven shaft support portion 52b bulge outward in the vehicle width direction, so that the end portion 21d of the crankshaft 21 and the end portion 27a of the driven shaft 27 May be covered from the outside in the vehicle width direction. FIG. 9 is a cross-sectional view of a support member 520 that is an example of this embodiment, and FIG. 10 is a side view of the transmission case 500. In these drawings, the same parts as those described above are denoted by the same reference numerals.

  As shown in FIG. 9, the support member 520 includes a drive shaft support portion 520a and a driven shaft support portion 520b. A bearing 53 is disposed inside the drive shaft support portion 520a, and an annular member 540 that rotates together with the end portion 21d of the crankshaft 21 is disposed inside the inner ring of the bearing 53. A nut 55 is fitted to the end 21d from the outside of the annular member 540 in the vehicle width direction. A center portion 520d of the outer wall of the drive shaft support portion 520a swells outward in the vehicle width direction, and the nut 55 is positioned inside thereof.

  Further, a bearing 56 is disposed inside the driven shaft support portion 520b, and an annular member 570 that rotates together with the end portion 27a of the driven shaft 27 is disposed inside the inner ring of the bearing 56. A nut 59 is fitted to the end 27a from the outside of the annular member 570 in the vehicle width direction. A center portion 520e of the outer wall of the driven shaft support portion 520b swells outward in the vehicle width direction, and a nut 59 is positioned inside thereof. In the example shown in FIG. 9 as well, the column portion 520 c is located between the bearing 53 and the bearing 56. Further, in this example, as shown in FIG. 10, the column portion 520 c is formed on the plane including the center line O1 of the crankshaft 21 and the centerline O2 of the driven shaft 27 from the driving shaft support portion 520 a. It extends to the support portion 520b.

  Further, in the support member 52 described above, the side surface 52d of the drive shaft support portion 52a and the side surface 52e of the driven shaft support portion 52b are located on the same plane, but the positional relationship between the side surfaces 52d and 52e is as follows. However, any one of them may be located outside in the vehicle width direction as compared with the other.

  Further, the retaining portion that restricts the movement of the bearing 53 to the inside of the case body 51 may be formed over a wider angular range than the retaining portion 51g shown in FIG. FIG. 11 is a side view of a case main body 510 which is an example of such a configuration. In FIG. 11, the same reference numerals are given to the same portions as the case main body 51. At the edge of the opening 51e of the case main body 510 shown in FIG. 11, a retaining portion 51i protruding inward is formed. The retaining portion 51i is formed, for example, over an angle range θ greater than 180 degrees. By doing so, rattling of the bearing 53 sandwiched between the retaining portion 51i and the support member 52 can be more effectively suppressed. In the example of FIG. 11 as well, similarly to FIG. 8, the retaining portion 51i is formed at a position opposite to the intake port 51c at the edge of the opening 51e.

  Further, in order to expose the end 21d of the crankshaft 21, the opening 52m formed in the support member 52 may be closed by a lid having an outer diameter larger than the opening 52m. FIG. 12 is a side view of a transmission case 500A having such a lid 91A, and FIG. 13 is a cross-sectional view taken along line XIII-XIII shown in FIG. In these drawings, the same reference numerals are assigned to the same portions as those of the transmission case 50 described above. The transmission case 500A has a support member 520A. An opening 52n for exposing the end 21d of the crankshaft 21 is formed in the support member 520A. The lid 91A has a flange portion 91a having an outer diameter larger than that of the opening 52n, and a fitting portion 91b having substantially the same diameter as the opening 52n. An annular groove is formed in a portion facing the flange portion 91a on the outer surface of the support member 52, and an annular seal member 92 that closes a gap between the flange portion 91a and the outer surface of the support member 52 is fitted into the groove. It has been. A screw is formed on the outer peripheral surface 91c of the fitting portion 91b. On the other hand, a screw is also formed on the inner peripheral surface of the opening 52n. The fitting portion 91b is fitted inside the opening 52n by these screws, and the lid 91A can be attached to and detached from the support member 52. A polygonal hole 91d is formed on the outer surface of the lid 91A. For example, a tool for rotating the lid 91A is fitted into the hole 91d when the lid 91A is attached to the support member 52.

1 is a side view of a motorcycle including an engine unit according to an embodiment of the present invention. It is a side view of the engine unit and the body frame. It is sectional drawing of the said engine unit. It is sectional drawing of the continuously variable transmission and clutch with which the said engine unit is provided. It is a side view of the said transmission case. It is a top view of the said transmission case. It is sectional drawing of the VII-VII line shown in FIG. It is a side view of a case main body with which the above-mentioned transmission case is provided. It is sectional drawing of the supporting member with which the transmission case in other embodiment of this invention is provided. It is a side view of the transmission case in other embodiment shown in FIG. It is a side view of the case body in other embodiments of the present invention. It is a side view of the transmission case in other embodiments of the present invention. It is sectional drawing in the XIII-XIII line | wire shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Motorcycle, 2 Body frame, 3 Front wheel, 4 Rear wheel, 5 Handle, 6 Steering shaft, 7 Front fork, 8 Storage case, 9 Seat, 10 Engine unit, 11 Rear arm, 12 Pivot shaft, 14 Cover, 20 Engine, 21 Crankshaft (drive shaft), 21d End of crankshaft, 22 Cylinder, 23 Piston, 24 Connecting rod, 25 Crankpin, 27 Driven shaft, 27a End of driven shaft, 28 Intermediate shaft, 29 Output shaft, 30 Continuously variable transmission, 31 Driving pulley, 32 Fixed sheave, 33 Movable sheave, 34 Weight roller, 35 Plate, 36 Fan, 39 Belt, 41 Driven pulley, 42 Fixed sheave, 43 Movable sheave, 44 Spring, 45 Spring Support member, 46, 48 collar, 47 Key, 50, 500 Transmission case, 51, 510 Case body, 51c Inlet, 51e, 51f Open, 51g, 58a Retaining part, 52, 520, 520A Support member, 52a, 520a Drive shaft support part, 52b, 520b Driven shaft support part, 52c, 520c Column, 52d Side surface of drive shaft support, 52e Side surface of driven shaft support, 52L Side surface of column, 53, 56 Bearing, 53a, 56a Outer ring, 54, 57, 540 , 570 annular member, 55, 59 nut, 58 annular member, 60 crank case, 80 clutch, 81 clutch inner, 82 clutch outer, 83 friction plate, 84 clutch plate, 85 diaphragm spring, 86 weight roller, 91, 91A lid.

Claims (13)

A drive shaft;
A driven shaft disposed away from the drive shaft;
A continuously variable transmission comprising a driving pulley provided on the driving shaft, a driven pulley provided on the driven shaft, and a belt wound around the driving pulley and the driven pulley;
A case for housing the continuously variable transmission,
The case includes a drive shaft support portion that supports an end portion of the drive shaft, a driven shaft support portion that supports an end portion of the driven shaft, and the drive shaft support portion and the driven shaft support portion. A strut portion spanned between,
An engine unit characterized by that. The engine unit according to claim 1, wherein
The case includes a support member having the drive shaft support portion, the driven shaft support portion, and the column portion, and a case main body that houses the continuously variable transmission and to which the support member is attached.
An engine unit characterized by that. The engine unit according to claim 2,
The drive shaft or the end of the driven shaft is exposed in an axial direction from an opening formed in the case body, and is rotatably supported by a bearing disposed outside the opening in the axial direction.
At least a part of the periphery of the opening is provided with a retaining portion that sandwiches the bearing with the support member.
An engine unit characterized by that. The engine unit according to claim 3,
The retaining portion sandwiches the outer ring of the bearing;
An engine unit characterized by that. The engine unit according to claim 3,
The retaining portion protrudes from the periphery of the opening of the case body toward the inside of the opening.
An engine unit characterized by that. The engine unit according to claim 3,
The retaining portion is attached to the case body.
An engine unit characterized by that. The engine unit according to claim 1, wherein
The drive shaft support portion is located in a direction in which the belt extends with respect to the driven shaft support portion.
An engine unit characterized by that. The engine unit according to claim 1, wherein
The drive shaft support portion, the driven shaft support portion, and the support column portion are formed so that their lateral sides on the vehicle width direction are flush with each other.
An engine unit characterized by that. The engine unit according to claim 1, wherein
A bearing for rotatably holding the end of the drive shaft or the driven shaft;
An annular member disposed inside the inner ring of the bearing and fitted into the end;
A nut that is fitted to the end from the outside in the axial direction than the annular member, and
The annular member is formed with a recess that is recessed in the axial direction,
The nut is fitted to the end and is received in the recess of the annular member.
An engine unit characterized by that. The engine unit according to claim 1, wherein
The case is formed with an inlet for introducing outside air into the case,
On the drive shaft, a fan that rotates together with the drive shaft and introduces outside air from the intake port is provided,
The drive shaft support portion is disposed away from the fan in the axial direction of the drive shaft,
The air inlet is located between the fan and the drive shaft support in the axial direction;
An engine unit characterized by that. The engine unit according to claim 1, wherein
The drive shaft is a crankshaft;
The drive shaft support portion is formed with an opening that exposes an end portion of the crank shaft in a state where the drive shaft support portion supports the crank shaft.
An engine unit characterized by that. The engine unit according to claim 11,
A lid that closes the opening formed in the drive shaft support portion and is detachable from the drive shaft support portion;
An engine unit characterized by that.   A straddle-type vehicle equipped with the engine unit according to claim 1.

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