JP7579375B2 - Power unit for saddle-type vehicles - Google Patents

Description

The present invention relates to a power unit for a saddle-type vehicle.

In recent years, research and development has been conducted into improving fuel efficiency, which contributes to energy efficiency, so that more people can have access to affordable, reliable, sustainable and advanced energy. As a technology related to fuel efficiency, Patent Document 1 discloses a power unit for a saddle-type vehicle equipped with a V-belt type continuously variable transmission. In Patent Document 1, a blower fan is provided on the side of the drive pulley, and cooling air is introduced to the back of the drive pulley and into the transmission chamber.

Patent No. 4293796

In the present technology for improving fuel efficiency, since the V-belt requires durability according to the environmental temperature, it is desirable to lower the environmental temperature as much as possible. However, the transmission chamber is easily affected by heat from the adjacent crank chamber. For this reason, if the environmental temperature of the V-belt is lowered only by introducing cooling air into the transmission chamber, it is likely that a large amount of cooling air needs to be introduced into the transmission chamber. Therefore, in order to prevent dust and the like from entering the transmission chamber, it is necessary to provide a labyrinth structure according to the large amount of air introduced, which results in a complicated structure.
The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a power unit for a saddle-ride type vehicle that is capable of reducing the temperature in the transmission compartment with a simple configuration, thereby contributing to improved energy efficiency.

A first aspect of the power unit for a saddle-ride type vehicle includes a casing, a crankshaft housed in the casing, and a belt-type continuously variable transmission that changes the speed of the driving force transmitted from the crankshaft and transmits it to drive wheels, wherein the casing includes a crank chamber in which the crankshaft is housed, and a transmission chamber in which the belt-type continuously variable transmission is housed, and an air layer space that forms an air layer is provided between the crank chamber and the transmission chamber, and the power unit includes an air guide mechanism that guides air to the air layer space, and the air guide mechanism includes a duct connected to the air layer space, and the duct extends outward in the vehicle width from the air layer space.
A second aspect of the power unit of a saddle-ride type vehicle is a power unit for a saddle-ride type vehicle comprising a casing, a crankshaft housed in the casing, and a belt-type continuously variable transmission that changes the speed of the driving force transmitted from the crankshaft and transmits it to driving wheels, wherein the casing comprises a crank chamber in which the crankshaft is housed, and a transmission chamber in which the belt-type continuously variable transmission is housed, an air layer space that forms an air layer is provided between the crank chamber and the transmission chamber, a wind guidance mechanism is provided to guide air into the air layer space, and a plurality of wings extending in the vehicle width direction are provided in the air layer space.

It is possible to provide a power unit for a saddle-type vehicle that can reduce the temperature in the transmission compartment with a simple configuration, which in turn can contribute to improving energy efficiency.

1 is a side view of a saddle-ride type vehicle according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the power unit according to the first embodiment. FIG. 2 is a perspective view of the power unit according to the first embodiment, as viewed from the left front. FIG. 11 is a cross-sectional view of a power unit according to a second embodiment. FIG. 11 is a cross-sectional view of a power unit according to a third embodiment.

Below, an embodiment of the present invention will be described with reference to the drawings. In the description, directions such as front, back, left, right, and up and down are the same as directions relative to the vehicle body unless otherwise specified. In addition, the symbol FR in each figure indicates the front of the vehicle body, the symbol UP indicates the upper part of the vehicle body, and the symbol LH indicates the left side of the vehicle body.

[Embodiment]
FIG. 1 is a side view of a saddle-ride type vehicle 10 according to an embodiment of the present invention.
The saddle-type vehicle 10 is a vehicle that includes a body frame 11, a power unit 12 supported by the body frame 11, a front fork 14 that supports a front wheel 13 so as to be freely steerable, a swing arm 16 that supports a rear wheel 15, and a seat 17 for a passenger.
The saddle-ride type vehicle 10 is a vehicle in which a passenger sits astride a seat 17. The seat 17 is provided above the rear portion of the body frame 11.

The body frame 11 includes a head pipe 18 provided at the front end of the body frame 11, a front frame 19 located rearward of the head pipe 18, and a rear frame 20 located rearward of the front frame 19. The front end of the front frame 19 is connected to the head pipe 18.
The seat 17 is supported by a rear frame 20 .

The front fork 14 is supported by the head pipe 18 so that it can be steered left and right. The front wheel 13 is supported by an axle 13a provided at the lower end of the front fork 14. A steering handle 21 that is held by the rider is attached to the upper end of the front fork 14.

The swing arm 16 is supported by a pivot shaft 22 that is supported by the body frame 11. The pivot shaft 22 is a shaft that extends horizontally in the vehicle width direction. The pivot shaft 22 is inserted into the front end of the swing arm 16. The swing arm 16 swings up and down about the pivot shaft 22.
The rear wheel 15 is supported by an axle 15 a provided at the rear end of a swing arm 16 .

The power unit 12 is disposed between the front wheels 13 and the rear wheels 15 and is supported by the body frame 11 .
The power unit 12 is an internal combustion engine. The power unit 12 includes a crankcase 23 and a cylinder portion 24 that houses a reciprocating piston. An exhaust device 25 is connected to an exhaust port of the cylinder portion 24.
The output of the power unit 12 is transmitted to the rear wheel 15 by a driving force transmission member that connects the power unit 12 and the rear wheel 15 .

The saddle-type vehicle 10 also includes a front fender 26 that covers the front wheel 13 from above, a rear fender 27 that covers the rear wheel 15 from above, a step 28 on which a rider places his or her feet, and a fuel tank 29 that stores fuel used by the power unit 12.
The front fender 26 is attached to the front fork 14. The rear fender 27 and the step 28 are provided below the seat 17. The fuel tank 29 is supported by the body frame 11.

The saddle-ride vehicle 10 of the first embodiment is a scooter-type saddle-ride vehicle. The saddle-ride vehicle 10 has a low step 28, a so-called step floor, on which a rider seated on the seat 17 places his/her feet. The power unit 12 of the saddle-ride vehicle 10 is a unit swing engine supported at the rear of the body frame 11. The power unit 12 has an engine body 30 and a swing arm 16 integrally provided. The rear wheel 15, which is a drive wheel, is journaled on the power unit 12, which is disposed at the rear of the vehicle. The power unit 12 is located directly below the seat 17 in a side view of the vehicle.

The engine body 30 comprises a crankcase (casing, first casing part) 23 and a cylinder part 24 extending forward from the crankcase 23. As shown in FIG. 2, the cylinder part 24 comprises, in order from the crankcase 23 side, a cylinder 24a, a cylinder head 24b, and a head cover 24c. The engine body 30 is a horizontal engine in which the cylinder axis 24d of the cylinder part 24 extends substantially horizontally in the fore-and-aft direction of the vehicle. In detail, the cylinder part 24 extends substantially horizontally towards the front of the vehicle with a slight upward slope when viewed from the side of the vehicle.

1, the rear frame 20 has a pair of left and right frame rising portions 20a that extend upward and rearward in front of the crankcase 23. A cylinder portion 24 that extends forward from the crankcase 23 is located in the space between the left and right frame rising portions 20a.
The power unit 12 is supported to be able to swing freely on a pivot shaft 22 of the frame rising portion 20 a via a link mechanism 31 provided above the power unit 12 .

Fig. 2 is a cross-sectional view of the power unit 12 according to the first embodiment. Fig. 2 is a cross-sectional view taken from above, passing through the axes of the camshaft 39, crank pin 38, crankshaft 32, belt-type continuously variable transmission 43, and reduction mechanism 45 of the valve gear of the cylinder head 24b.
The crankcase 23 supports a crankshaft (drive shaft) 32 extending in the left-right direction (vehicle width direction). A crank chamber 35 that houses the crankshaft 32 is formed in the crankcase 23. A pair of left and right support walls 35a, 35b are provided in the crank chamber 35, which are perpendicular to the crankshaft 32. The crankshaft 32 is rotatably supported by the support walls 35a, 35b via bearings.

A piston 36 is connected to the crankshaft 32 via a connecting rod 37 and a crank pin 38. The piston 36 reciprocates within the cylinder 24a in the axial direction of the cylinder axis 24d.

A drive sprocket 61 is attached to the crankshaft 32 on the left side (one side in the vehicle width direction) of the connecting rod 37. A cam chain 62 is wound around the drive sprocket 61. The cam chain 62 passes through a cam chain chamber 66 formed on the left side of the cylinder section 24 and is wound around a driven sprocket 63 of the camshaft 39 of the valve train. The cam chain chamber 66 is provided across the crankcase 23, the cylinder 24a, and the cylinder head 24b, and extends in the axial direction of the cylinder section 24.

The camshaft 39 of the valve train is parallel to the crankshaft 32. The valve train is mounted in the cylinder head 24b. The rotation of the crankshaft 32 is transmitted to the camshaft 39 of the valve train by a cam chain 62. The camshaft 39 rotates once for every two rotations of the crankshaft 32.

On the left side of the drive sprocket 61, a separator 67 having a generally annular shape is disposed in the opening 23b of the crankcase 23 so as to close the opening 23b. The separator 67 is fixed to the crankcase 23 with bolts 68. A seal member 69a is attached to the outer periphery of the separator 67 to seal the gap between the separator 67 and the crankcase 23. An oil seal 69b is attached to the inner periphery of the separator 67 to seal the gap between the separator 67 and the crankshaft 32. In this embodiment, a cylindrical portion 67a extending in the axial direction of the crankshaft 32 is formed on the left surface of the separator 67. The crankshaft 32 is inserted into the cylindrical portion 67a. The cylindrical portion 67a surrounds the crankshaft 32 from the outer periphery while being spaced apart from the crankshaft 32.

The crankcase 23 is integrally provided with a transmission case portion (casing, second casing portion) 40 that extends rearward from the left side portion of the crank chamber 35. The transmission case portion 40 extends from a lateral portion of the crank chamber 35 to the left side of the rear wheel 15.
The transmission case portion 40 is formed in a case shape with an open outer surface in the vehicle width direction. The open portion of the outer surface of the transmission case portion 40 is closed by a case cover (casing, third casing portion) 41 attached to the outer surface of the transmission case portion 40.

A hollow transmission chamber 42 is defined by the transmission case 40 and the case cover 41. One end 32a of the crankshaft 32 (one end in the vehicle width direction and one end in the axial direction) is positioned within the transmission chamber 42, penetrating the left support wall 35a and the separator 67.
The transmission chamber 42 accommodates a belt-type continuously variable transmission 43 that changes the speed of the rotation of the crankshaft 32 and transmits it to the rear wheel 15, a centrifugal clutch mechanism 44, and a reduction mechanism 45 made up of a plurality of gears.

The belt-type continuously variable transmission 43 includes a drive pulley 43a provided on one end 32a of the crankshaft 32, an output shaft (driven shaft) 43b provided at the rear of the transmission case portion 40, a driven pulley 43c supported by the output shaft 43b, and a V-belt 43d connecting the drive pulley 43a and the driven pulley 43c.
The drive pulley 43 a has a fixed sheave 120 fixed to the crankshaft 32 , and a movable sheave 121 disposed opposite the fixed sheave and supported so as to be movable in the axial direction of the crankshaft 32 .

The clutch mechanism 44 is provided on the output shaft 43b. The output shaft 43b is connected to the axle 15a of the rear wheel 15 via a reduction gear mechanism 45.
The driving force of the crankshaft 32 is transmitted to the axle 15 a of the rear wheel 15 via a belt-type continuously variable transmission 43 , a clutch mechanism 44 , and a reduction mechanism 45 .

The other end 32b of the crankshaft 32 (the other end in the vehicle width direction, the other end in the axial direction) extends outward from the crankcase 23 through the right support wall 35b. A flywheel 47 that rotates integrally with the crankshaft 32 is fixed to the other end 32b of the crankshaft 32. A generator 48 that generates electricity by the rotation of the crankshaft 32 is provided inside the flywheel 47. The generator 48 includes a magnet 48a fixed to the inner circumference of the flywheel 47 and a coil 48b that is disposed radially inward of the flywheel 47 relative to the magnet 48a. The coil 48b is fixed to the crankcase 23.

The power unit 12 is provided with an air blower 50 that blows air toward the engine body 30 to air-cool the engine body 30.
The blower device 50 includes a crankshaft 32, a cooling fan 51 fixed to the crankshaft 32 and rotating integrally with the crankshaft 32, a fan cover 52 that covers the cooling fan 51 from the outside, and a cylinder portion cover 53 that covers the cylinder portion 24.

The cylinder section cover 53 is provided to surround the cylinder 24a and cylinder head 24b around the cylinder axis 24d. The cylinder section cover 53 covers the cylinder 24a and cylinder head 24b over substantially the entire circumference. In this embodiment, the cylinder section cover 53 covers the left front side of the crankcase 23 and extends to the vicinity of the boundary with the case cover 41. The cylinder section cover 53 is fixed to the left front side of the crankcase 23 with a fixing member 94.

The space formed between the cylinder part cover 53 and the cylinder part 24 is an air passage 54 through which the air current sent by the cooling fan 51 passes. In the air passage 54, cooling fins 49 are provided on the outer surface of the cylinder 24a.
The fan cover 52 is attached to the outer side surface 23a of the crankcase 23 in the vehicle width direction, and covers the outer side surface 23a and the cooling fan 51 from the outside in the vehicle width direction. A front edge portion of the fan cover 52 is connected to a rear edge portion of the cylinder portion cover 53, and the space inside the fan cover 52 communicates with an air passage 54.

The cooling fan 51 is fastened to a side surface on the outer side in the vehicle width direction of the flywheel 47. That is, the cooling fan 51 is fixed to an axial end of the crankshaft 32 via the flywheel 47.
The cooling fan 51 rotates integrally with the crankshaft 32, drawing in air from the outside through the fan cover 52 as shown by arrow A1, and blowing the air drawn into the inside of the fan cover 52 radially outward from the cooling fan 51 as shown by arrow A2.
The airflow blown out by the cooling fan 51 passes through the air passage 54 as indicated by the arrow A3, reaches the periphery of the cylinder 24a and the cylinder head 24b, and cools the cylinder 24a and the cylinder head 24b.
That is, the engine body 30 is of a forced air-cooling type in which the engine body 30 is forcibly air-cooled by the air blown by the cooling fan 51 driven by the crankshaft 32 .

As shown in FIG. 2 , the power unit 12 of the present embodiment has an air layer space 100 between the crank chamber 35 and the transmission chamber 42 .
Specifically, a front opening (first opening) 70 is formed on the front surface of the crankcase 23. The front opening 70 is formed between the cylinder portion 24 and the drive pulley 43a in the vehicle width direction. In other words, the front opening 70 is formed to the left of the cylinder portion 24 and to the right of the drive pulley 43a. Here, the front opening 70 does not have to be in a position overlapping with the drive pulley 43a in a side view of the vehicle body, and may be formed forward of the front end of the drive pulley 43a. The front opening 70 has an upper inner peripheral edge 71 (see FIG. 3), a lower inner peripheral edge 72, a left inner peripheral edge 73, and a right inner peripheral edge 74. The front opening 70 is formed by the surrounding shape of the upper inner peripheral edge 71, the lower inner peripheral edge 72, the left inner peripheral edge 73, and the right inner peripheral edge 74.

A rear opening (second opening, exhaust port) 80 is formed on the rear surface of the crankcase 23. The rear opening 80 is formed behind the front opening 70 in the front-rear direction. The position of the rear opening 80 in the vehicle width direction overlaps with the position of the front opening 70 in the vehicle width direction. This makes it easy to connect the front opening 70 and the rear opening 80 in a straight line in the front-rear direction. This makes it easy to make the air that flows in from the front opening 70 flow out from the rear opening 80 quickly. The rear opening 80 has an upper inner peripheral edge (not shown), a lower inner peripheral edge 82, a left inner peripheral edge 83, and a right inner peripheral edge 84. The rear opening 80 is formed by the surrounding shape of the upper inner peripheral edge, the lower inner peripheral edge 82, the left inner peripheral edge 83, and the right inner peripheral edge 84.
The rear opening 80 faces the rear wheel 15. A right inner peripheral edge 84 of the rear opening 80 is located to the right of the left end 15b of the rear wheel 15. A left inner peripheral edge 83 of the rear opening 80 is located to the left of the left end 15b of the rear wheel 15.

In the crankcase 23 of this embodiment, a metallic air space forming member 90 is disposed on the transmission chamber 42 side so as to straddle the front opening 70 and the rear opening 80. In this embodiment, the air space forming member 90 is illustrated as being made of metal, but the air space forming member 90 is not limited to being made of metal and may be made of resin.

The air layer forming member 90 is disposed inside the crankcase 23 to partition the interior of the crankcase 23. The air layer forming member 90 is formed in a curved plate shape. The air layer forming member 90 has a partition wall portion 90b having an outer peripheral shape corresponding to the inner surface shape of the crankcase 23, a fixed portion 90c extending leftward from the front end of the partition wall portion 90b, and a fixed portion 90d extending rearward from the rear end of the partition wall portion 90b. The partition wall portion 90b has a hole portion 90a into which the left end (tip) of the cylindrical portion 67a of the separator 67 is fitted and through which the crankshaft 32 inside the cylindrical portion 67a is inserted.

The crankshaft 32 is inserted into the hole 90a of the air layer forming member 90, and the fixed portions 90c and 90d are fixed to the crankcase 23 by fixing members 94 and 95. The fixing members 94 and 95 are, for example, bolts. This fixes the air layer forming member 90 to the crankshaft 32 so that it cannot move in the axial direction.

Here, the partition wall portion 90b of the air layer forming member 90 extends from the front opening 70 to the rear opening 80. The front fixed portion 90c is fixed to the inner surface of the crankcase 23 to the left of the left inner peripheral edge 73 of the front opening 70. The rear fixed portion 90d is fixed to the inner surface of the crankcase 23 to the left of the left inner peripheral edge 83 of the rear opening 80. As a result, a space surrounded by the crankcase 23, the air layer forming member 90, and the separator 67 is formed from the front opening 70 to the rear opening 80. Here, the separator 67 is a member that closes the opening 23b of the crankcase 23 and is also a member that constitutes the wall shape of the crankcase 23. Therefore, if the separator 67 is considered to be a part of the shape of the crankcase 23, it can be said that a space surrounded by the crankcase 23 and the air layer forming member 90 is formed from the front opening 70 to the rear opening 80. Therefore, in the following, when referring to the crankcase 23, it is basically meant to include the separator 67.

A crank chamber 35 in this embodiment is formed by the space surrounded by the crankcase 23. A transmission chamber 42 in this embodiment is formed by the space surrounded by the air layer forming member 90, the transmission case portion 40 of the crankcase 23, and the case cover 41.
The air layer forming member 90 and the space surrounded by the crankcase 23 form an air layer space 100 in this embodiment that forms an air layer.
Therefore, the crank chamber 35 and the transmission chamber 42 are separated by the air layer space 100. This makes it difficult for the high heat of the crank chamber 35 to be transmitted to the transmission chamber 42.

3 is a perspective view of the power unit 12 according to the first embodiment, as viewed from the front left. In FIG. 3, the cylinder portion cover 53 is omitted.
A wing 96 is disposed in the air layer space 100. In this embodiment, the wing 96 is formed on the air layer forming member 90. The wing 96 is formed on the right surface of the partition wall portion 90b. A plurality of wings 96 are formed at intervals in the up-down direction. The wing 96 has a thickness in the up-down direction and extends in the front-rear direction. The right end of the wing 96 is formed so as to be able to abut against the left surface of the crankcase 23 when the air layer forming member 90 is attached.

The front opening 70 of the air layer space 100 is covered from the front by the cylinder section cover 53, and is configured so that the cooling air inside the cylinder section cover 53 can be guided. The air guide mechanism 110 of this embodiment is configured by the air blower 50, which includes the cooling fan 51 and the cylinder section cover (air guide cover) 53 that covers the cylinder section 24.

In this embodiment, when the crankshaft 32 rotates and the cooling fan 51 rotates, cooling air is taken in from the outside into the fan cover 52 as shown by the arrow A1, and the cooling air flows through the air passage 54 in the cylinder section cover 53. The cooling air is guided by the cylinder section cover 53 and is guided into the air layer space 100 while cooling the cylinder section 24.

When the cooling air is guided to the air layer space 100 through the front opening 70 as shown by the arrow A4, it passes through the air layer space 100 and is exhausted from the rear opening 80 as shown by the arrow A5. When the cooling air passes through the air layer space 100, heat is transferred from the air layer forming member 90, and the cooling air passes through the air layer space 100 while cooling the air layer forming member 90. Therefore, the air layer forming member 90 is cooled, and the transmission chamber 42 is cooled. In particular, in this embodiment, the air layer forming member 90 is provided with a wing 96, so that the contact area of the air layer forming member 90 with the cooling air is increased, making it easier for the air layer forming member 90 to be cooled, and the transmission chamber 42 to be cooled. In addition, the heated and exhausted cooling air hits the rear wheel 15, making it easier to warm the rear wheel 15.

In general, the higher the temperature environment, the lower the durability of the V-belt. For this reason, if the crank chamber 35 and the transmission chamber 42 are not separated by the air layer space 100, the V-belt will heat up due to friction during driving, and the transmission chamber 42 will easily heat up due to heat received from the engine body 30. For this reason, in order to ensure the belt replacement interval, the V-belt is made hard and thick.

In contrast, in this embodiment, the crank chamber 35 and the transmission chamber 42 are separated by the air layer space 100, so that the high heat of the crank chamber 35 is less likely to be transmitted to the transmission chamber 42. In addition, the transmission chamber 42 is cooled by the cooling air passing through the air layer space 100, so that the transmission chamber 42 is prevented from becoming too hot. Therefore, in this embodiment, the temperature environment of the transmission chamber 42 is easily made to be a temperature environment that easily improves the durability of the V-belt 43d, so that the V-belt 43d can be made softer and thinner while ensuring the replacement interval of the V-belt 43d. Therefore, in this embodiment, the weight of the V-belt 43d can be reduced, and the frictional resistance of the V-belt 43d can be easily suppressed, and improved fuel efficiency can be expected.

In addition, in this embodiment, the case cover 41 does not have an opening for taking in the traveling wind into the transmission chamber 42. This prevents dust and the like from entering the transmission chamber 42. In addition, since there is no need to take in the traveling wind as cooling air into the transmission chamber 42, the cooling fins of the fixed sheave 120 of the drive pulley 43a can be omitted. In other words, the back surface (left surface) of the fixed sheave 120 can be made into a smooth, flat surface 120a without any irregularities. This makes it easier to suppress air turbulence in the transmission chamber 42 caused by the fixed sheave 120, suppresses the air resistance experienced by the fixed sheave 120, improves fuel efficiency, and makes it easier to simplify the physical shape of the fixed sheave 120.

As described above, according to the first embodiment to which the present invention is applied, the power unit 12 of the saddle-ride type vehicle 10 includes the crankcase 23, the transmission case section 40, the case cover 41, the crankshaft 32 housed in the crankcase 23, and the belt-type continuously variable transmission 43 that changes the speed of the driving force transmitted from the crankshaft 32 and transmits it to the rear wheel 15. In the power unit 12 of the saddle-ride type vehicle, the crankcase 23, the transmission case section 40, and the case cover 41 include the crank chamber 35 in which the crankshaft 32 is housed, and the transmission chamber 42 in which the belt-type continuously variable transmission 43 is housed. Between the crank chamber 35 and the transmission chamber 42, an air layer space 100 that forms an air layer is provided, and the power unit 12 includes an air guide mechanism 110 that guides air to the air layer space 100.
According to this configuration, by introducing air into the air layer space 100 between the crank chamber 35 and the transmission chamber 42, the temperature of the transmission chamber 42 can be reduced without introducing cooling air directly into the transmission chamber 42. This makes it possible to reduce the temperature of the transmission chamber 42 with a simple configuration, which in turn contributes to improved energy efficiency.

In this embodiment, the engine has a cylinder section 24 supported by the crankcase 23, and the air guide mechanism 110 has a cooling fan 51 that cools the cylinder section 24, and a cylinder section cover 53 that guides the cooling air from the cooling fan 51 to the front of the air layer space 100.
According to this configuration, by utilizing the cooling fan 51 for cooling the cylinder portion 24, it is possible to introduce cooling air into the air layer space 100 without providing a special mechanism for introducing cooling air.

In this embodiment, the air layer space 100 is provided with a plurality of wings 96 extending in the vehicle width direction.
According to this configuration, the cooling air can be actively introduced into the air layer space 100, and the contact area with the cooling air can be increased, thereby improving the cooling performance.

In this embodiment, a rear opening 80 is formed in the air layer space 100 , and the rear opening 80 faces the rear wheel 15 .
According to this configuration, the rear wheel 15 can be heated by the exhaust air from the air layer space 100 that has received heat from the crank chamber 35 and the transmission chamber 42.

In addition, in this embodiment, the belt-type continuously variable transmission 43 comprises a drive pulley 43a provided at one axial end of the crankshaft 32, a driven pulley 43c provided on an output shaft 43b journalled parallel to the crankshaft 32, and a V-belt 43d stretched between the drive pulley 43a and the driven pulley 43c, and the drive pulley 43a has a fixed sheave 120 fixed to the crankshaft 32, and a movable sheave 121 arranged opposite the fixed sheave 120 and supported so as to be freely movable in the axial direction of the crankshaft 32, and the back surface of the fixed sheave 120 is a flat surface 120a on which no fins are formed.
According to this configuration, the transmission chamber 42 can be cooled even with a sheave shape that does not increase air resistance.

[Second embodiment]
A second embodiment of the present invention will be described below. In this second embodiment, parts configured similarly to those in the first embodiment are given the same reference numerals and descriptions thereof will be omitted.

Fig. 4 is a cross-sectional view of a power unit 212 according to the second embodiment. Fig. 4 corresponds to Fig. 2 of the first embodiment.
A power unit 212 of the second embodiment differs from the first embodiment in that a duct 270 that guides air to the front opening 70 is provided.

In detail, the cylinder cover 53 according to the second embodiment has a hole-shaped duct rear support portion 253a formed in front of the front opening 70 of the air layer space 100. The duct 270 is inserted and supported in the duct rear support portion 253a.

The duct 270 is a hollow member extending in the front-rear direction. The duct 270 has an inlet 271 at the front end and an outlet 272 at the rear end. The duct 270 extends in a curved manner so that the inlet 271 is disposed on the outer side of the outlet 272 in the vehicle width direction. The duct 270 is supported by the duct rear support part 253a with the outlet 272 connected to the front opening 70. The front end part of the duct 270 on the inlet 271 side is supported by the duct front support part 253b of the cylinder part cover 53 on the left side of the cylinder part 24. This makes it easier for the running wind to flow into the inlet 271 without being obstructed by the cylinder part 24.
The cylinder portion cover 53 and the duct 270 constitute the air guide mechanism 210 of the second embodiment.

In this embodiment, when the saddle-ride type vehicle 10 is traveling, traveling wind is taken in from the inlet 271 of the duct 270 as shown by arrow A21. The traveling wind flows along the duct 270, is guided to the air layer space 100 through the front opening 70 as shown by arrow A22, and is exhausted from the rear opening 80 as shown by arrow A23. Therefore, in this embodiment as well, the traveling wind flows through the air layer space 100 as cooling wind, and the transmission chamber 42 is cooled.

As described above, according to the second embodiment of the present invention, the power unit 212 of the saddle-ride type vehicle 10 is equipped with an air guide mechanism 210 that guides air into the air layer space 100. Therefore, even in the second embodiment, the temperature of the transmission chamber 42 can be reduced with a simple configuration, which in turn contributes to energy efficiency.

In particular, in this embodiment, the air guide mechanism 210 includes a duct 270 connected to the air layer space 100, and the duct 270 extends outward in the vehicle width direction from the air layer space 100.
According to this configuration, the wind generated while the vehicle is traveling can be effectively guided to the air layer space 100, and the temperature in the transmission chamber 42 can be reduced with a simple configuration.

[Third embodiment]
A third embodiment to which the present invention is applied will be described below. In this third embodiment, parts configured similarly to the first embodiment are given the same reference numerals and descriptions thereof will be omitted.

Fig. 5 is a cross-sectional view of a power unit 312 according to the third embodiment. Fig. 5 corresponds to Fig. 2 of the first embodiment.
The power unit 312 of the third embodiment differs from the first embodiment in that the crankcase (casing, first casing part) 323 in which the crank chamber 35 is formed and the transmission case 340 (casing, second casing part) in which the transmission chamber 42 is formed are separate bodies.

In the crankcase 323 of the third embodiment, the rear left transmission case section 40 is omitted compared to the crankcase 23 of the first embodiment. The rear left end section 323c of the crankcase 323 is located in front of the rear wheel 15 and to the right of the left end 15b of the rear wheel 15. The crankcase 323 of the third embodiment does not have a front opening 70 or a rear opening 80.

The transmission case 340 according to the third embodiment is, so to speak, a structure in which the transmission case section 40 and the air layer forming member 90 according to the first embodiment are integrally formed. Therefore, in the transmission case 340, the fixing member 95 and its fixing portion, which are only for fixing the air layer forming member 90 to the transmission case section 40 according to the first embodiment, are omitted. In addition, the transmission case 340 is formed with a hole portion 340a through which the cylindrical portion 67a of the separator 67 and one end portion 32a of the crankshaft 32 are inserted, and the fixing member 94 of the cylinder portion cover 53 is fixed.

The transmission case 340 is bolted to the crankcase 323. That is, a plurality of fixing holes 340b are formed in the transmission case 340 on the outer periphery of the crankshaft 32, i.e., on the outer periphery of the movable sheave 121 of the drive pulley 41a. The fixing holes 340b are formed at intervals in the circumferential direction of the crankshaft 32, for example, four fixing holes 340b. Corresponding to the fixing holes 340b, the transmission case 340 is formed with a cylindrical abutment portion 340c protruding to the right from the right outer surface. The abutment portion 340c abuts against the left surface of the crankcase 323. In this state, the bolt 301 is inserted into the fixing hole 340b, and the inserted bolt 301 is fastened to the crankcase 323. As a result, the transmission case 340 is bolted to the crankcase 323 and bolted to the crankcase 323.

Here, the crankcase 323 and the transmission case 340 are separated by a predetermined distance in the vehicle width direction by the abutment portion 340c. As a result, an air layer space 300 into which air can enter is formed between the crankcase 323 and the transmission case 340. Therefore, in the third embodiment, the power unit 312 also separates the crank chamber 35 and the transmission chamber 42 by the air layer space 300. In addition, a wing 396 is formed in the transmission case 340 corresponding to the wing 96, and the wing 396 is arranged in the air layer space 300. The cooling air is guided into the air layer space 300 by the air guide mechanism 110 through the front end 370 of the air layer space 300. The cooling air is exhausted from the air layer space 300 through the rear end (air exhaust port) 380 of the air layer space 300. The left rear end 323c of the crankcase 323 is located forward of the rear wheel 15 and to the right of the left end 15b of the rear wheel 15, so even in this embodiment, the rear end 380 of the air layer space 300 faces the rear wheel 15.

As described above, according to the third embodiment to which the present invention is applied, the power unit 312 of the saddle-ride type vehicle 10 has an air layer space 300 that forms an air layer between the crank chamber 35 and the transmission chamber 42, and is equipped with an air guide mechanism 110 that guides air into the air layer space 300. Therefore, even in the third embodiment, the temperature of the transmission chamber 42 can be reduced with a simple configuration, which in turn can contribute to energy efficiency.

[Other embodiments]
The above-described embodiment merely shows one aspect of the present invention, and any modification and application can be made without departing from the spirit and scope of the present invention.

In the above embodiment, in order to facilitate cooling of the transmission chamber 42, it is preferable that the wings 96, 396 are provided on the air layer forming member 90 or the transmission case 340, but they may also be provided on the crankcase 23, 323.

In the above embodiment, the blower device 50 is configured to guide cooling air to the air layer spaces 100, 300 using a cooling device that cools the engine body 30, but a blower device dedicated to the air layer spaces 100, 300 may also be provided.

In the above embodiment, a configuration in which no opening is formed in the case cover 41 for taking in the traveling wind into the transmission chamber 42 has been exemplified, but an opening for taking in the traveling wind into the transmission chamber 42 may be formed in the case cover 41. When an opening for taking in the traveling wind into the transmission chamber 42 is formed in the case cover 41, the cooling wind can be taken into the transmission chamber 42 without being affected by the high temperature of the crank chamber 35, so that the cooling effect of the crank chamber 35 can be improved with a simple configuration.

In the above third embodiment, the configuration in which the air guide mechanism 110 guides air to the air layer space 300 has been described, but a duct 270 may be provided that is connected to the air layer space 300 and extends outwardly of the vehicle width from the air layer space 300. That is, as in the second embodiment, the configuration in which the air guide mechanism 210 guides air to the air layer space 300 may also be used.

In the third embodiment, the crankcase 323 has an opening 23b, and the crankshaft 32 is supported via a separator 67 that closes the opening 23b. However, the opening 23b may be a hole of a size corresponding to the outer diameter of the crankshaft 32, and the crankcase 323 may support the crankshaft 32 via, for example, an oil seal. In other words, the separator 67 may be omitted, and the crankcase 323 may be shaped so that it is integrated with the separator 67.

In the above embodiment, a motorcycle having a front wheel 13 and a rear wheel 15 is used as an example of the saddle-type vehicle 10, but the present invention is not limited to this, and the present invention can be applied to a three-wheel saddle-type vehicle having two front or two rear wheels, or a saddle-type vehicle having four or more wheels.

[Configuration supported by the above embodiment]
The above embodiment supports the following configurations.

(Configuration 1) A power unit for a saddle-ride type vehicle comprising a casing, a crankshaft housed in the casing, and a belt-type continuously variable transmission that changes the speed of the driving force transmitted from the crankshaft and transmits it to driving wheels, wherein the casing comprises a crank chamber in which the crankshaft is housed, and a transmission chamber in which the belt-type continuously variable transmission is housed, and an air layer space that forms an air layer is provided between the crank chamber and the transmission chamber, and the power unit for a saddle-ride type vehicle comprises an air guide mechanism that guides air into the air layer space.
According to this configuration, the temperature of the transmission chamber can be reduced by directing air into the air space between the crank chamber and the transmission chamber, without directly introducing cooling air into the transmission chamber. This makes it possible to reduce the temperature of the transmission chamber with a simple configuration, which in turn contributes to improving energy efficiency.

(Configuration 2) A power unit for a saddle-ride type vehicle as described in configuration 1, further comprising a cylinder portion supported by the casing, and the air guide mechanism comprises a cooling fan that cools the cylinder portion, and an air guide cover that guides cooling air from the cooling fan to the front of the air layer space.
According to this configuration, by utilizing a cooling fan to cool the cylinder portion, it is possible to introduce cooling air into the air layer space without providing a special mechanism for introducing cooling air.

(Configuration 3) A power unit for a saddle-ride type vehicle as described in configuration 1, characterized in that the air guide mechanism includes a duct connected to the air layer space, and the duct extends outwardly of the vehicle width from the air layer space.
According to this configuration, the wind generated while traveling can be effectively guided to the air layer space, and the temperature in the transmission chamber can be reduced with a simple configuration.

(Configuration 4) A power unit for a saddle-ride type vehicle according to any one of configurations 1 to 3, characterized in that a plurality of wings extending in the vehicle width direction are provided in the air layer space.
According to this configuration, the cooling air can be actively introduced into the air layer space, and the contact area with the cooling air can be increased, thereby improving the cooling performance.

(Configuration 5) A power unit for a saddle-ride type vehicle as described in any one of configurations 1 to 4, characterized in that an exhaust port is formed in the air layer space, and the exhaust port faces the drive wheels.
According to this configuration, the drive wheels can be warmed by the exhaust air from the air layer space that has received heat from the crank chamber and the transmission chamber.

(Configuration 6) A power unit for a saddle-type vehicle described in any one of configurations 1 to 5, characterized in that the belt-type continuously variable transmission comprises a drive pulley provided at one axial end of the crankshaft, a driven pulley provided on a driven shaft journaled parallel to the crankshaft, and a V-belt stretched between the drive pulley and the driven pulley, the drive pulley having a fixed sheave fixed to the crankshaft and a movable sheave arranged opposite the fixed sheave and supported so as to be freely movable in the axial direction of the crankshaft, and the back surface of the fixed sheave is a flat surface on which no fins are formed.
According to this configuration, the transmission chamber can be cooled even with a sheave shape that does not increase air resistance.

10 Saddle type vehicle 12 Power unit (power unit of saddle type vehicle)
15 Rear wheels (drive wheels)
23 Crankcase (casing)
32 Crankshaft 35 Crank chamber 40 Transmission case (casing)
41 Case cover (casing)
42 Transmission chamber 43 Belt type continuously variable transmission 43a Drive pulley 43a1 Fixed sheave 43a2 Movable sheave 43b Output shaft (driven shaft)
43c Driven pulley 43d V-belt 51 Cooling fan 53 Cylinder section cover (air guide cover)
80 Rear opening (ventilation port)
96 Wing 100 Air layer space 110 Air guide mechanism 120 Fixed sheave 120a Flat surface 121 Movable sheave 210 Air guide mechanism 212 Power unit (power unit of saddle-ride type vehicle)
270 duct 300 air layer space 312 power unit (power unit of saddle-type vehicle)
323 Crankcase (Casing)
340 Transmission case (casing)
380 Rear end (exhaust port)
396 Wing

Claims (7)

A power unit for a saddle-ride type vehicle includes a casing (23, 40, 41, 323, 340), a crankshaft (32) accommodated in the casing (23, 40, 41, 323, 340), and a belt-type continuously variable transmission (43) that changes the speed of a driving force transmitted from the crankshaft (32) and transmits it to a driving wheel (15),
The casing (23, 40, 41, 323, 340) includes a crank chamber (35) in which the crankshaft (32) is housed, and a transmission chamber (42) in which the belt-type continuously variable transmission (43) is housed,
An air layer space (100, 300) for forming an air layer is provided between the crank chamber (35) and the transmission chamber (42),
A ventilation mechanism (110, 210) for guiding air to the air layer space (100, 300),
The air guide mechanism (210) includes a duct (270) connected to the air layer space (100, 300),
The power unit for a saddle-ride type vehicle, wherein the duct (270) extends outwardly of the vehicle width from the air layer space (100, 300). A power unit for a saddle-ride type vehicle includes a casing (23, 40, 41, 323, 340), a crankshaft (32) accommodated in the casing (23, 40, 41, 323, 340), and a belt-type continuously variable transmission (43) that changes the speed of a driving force transmitted from the crankshaft (32) and transmits it to a driving wheel (15),
The casing (23, 40, 41, 323, 340) includes a crank chamber (35) in which the crankshaft (32) is housed, and a transmission chamber (42) in which the belt-type continuously variable transmission (43) is housed,
An air layer space (100, 300) for forming an air layer is provided between the crank chamber (35) and the transmission chamber (42),
A ventilation mechanism (110, 210) for guiding air to the air layer space (100, 300),
A power unit for a saddle-ride type vehicle, characterized in that a plurality of wings (96, 396) extending in a vehicle width direction are provided in the air layer space (100, 300). an air layer forming member (90) provided between the crank chamber (35) and the transmission chamber (42);
The air layer space (100, 300) is formed by a space surrounded by the casing (23, 40, 41, 323, 340) and the air layer forming member (90).
3. The power unit for a saddle-ride type vehicle according to claim 1 or 2. The air layer space (100, 300) includes a front opening (70) and a rear opening (80) that overlaps with the front opening (70) in the vehicle width direction;
The front opening (70) is provided with a ventilation mechanism (110, 210) through which air is guided.
3. The power unit for a saddle-ride type vehicle according to claim 1 or 2. A cylinder portion (24) supported by the casing (23, 323),
The power unit for a saddle-ride type vehicle according to claim 1 or 2, characterized in that the air guide mechanism ( 110) comprises a cooling fan (51) that cools the cylinder portion (24), and an air guide cover (53) that guides cooling air from the cooling fan (51) to the front of the air layer space (100, 300). An exhaust port (80, 380) is formed in the air layer space (100, 300),
3. The power unit for a saddle-ride type vehicle according to claim 1 or 2 , wherein the exhaust port (80, 380) faces the drive wheels (15). The belt-type continuously variable transmission (43) includes a drive pulley (43a) provided at one axial end of the crankshaft (32), a driven pulley (43c) provided on a driven shaft (43b) journaled in parallel to the crankshaft (32), and a V-belt (43d) stretched between the drive pulley (43a) and the driven pulley (43c),
The drive pulley (43a) has a fixed sheave (120) fixed to the crankshaft (32) and a movable sheave (121) disposed opposite the fixed sheave (120) and supported so as to be movable in the axial direction of the crankshaft (32),
3. The power unit for a saddle-ride type vehicle according to claim 1, wherein a back surface of the fixed sheave (120) is a flat surface (120a) on which no fins are formed.

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