Straddle-type vehicle

ES 2 323 905 T3

DESCRIPTION

Straddle-type vehicle.

Background

The present invention relates to a straddle-type vehicle such as a motorcycle. More particularly, the invention relates to a vehicle of the type provided with an engine assembly, which comprises a four-stroke engine and a continuously variable transmission of the belt type.

For example, JP-B-61-040864 discloses a motorcycle provided with an engine assembly, which comprises a two-stroke engine arranged towards the rear of a vertically extending lower frame with an axis of a vertically extending cylinder. With the engine assembly, a belt type continuously variable transmission (a continuously variable transmission referred to hereinafter as "CVT" is arranged in a crankcase of the crankshaft, which supports a crankshaft and an output shaft. The output shaft of the engine assembly is connected to a rear wheel through a power transmission mechanism such as a belt, chain, drive shaft, and so on. Thus, the motive power is transmitted to the rear wheel through the power transmission mechanism from the output shaft of the engine assembly.

The motorcycle, which is described in JP-B-61-040864 and on which a belt-type CVT transmission is mounted, adopts the same configuration as that of normal motorcycles but does not need a gear change and is of great comfort.

In order to achieve a further improvement in comfort, it is requested to mount a four-stroke engine, which has a relatively large torque at low speed, instead of the two-stroke engine of the motorcycle described in JP-B. -61-040864.

However, there are problems when a two-stroke engine of the type of the motorcycle described in JP-B-61-040864 is replaced by a four-stroke engine.

In a four-stroke engine, the intake valves, the exhaust valves and the valve actuation mechanism for operating the intake valves and the exhaust valves are arranged in the cylinder head. Furthermore, an oil reservoir part is formed below the crankshaft to store a lubricating oil for lubricating the engine. Therefore, a four-stroke engine is relatively large in the axial direction of the cylinder compared to a two-stroke engine. When attempting to apply such a four-stroke engine on a motorcycle, in which the engine is arranged at the rear of a vertically extending lower frame with vertically extending cylinder shafts, the vehicle cannot be increased in height. total, or reduce to a minimum ground level since the motor is large in length in the axial direction of the cylinders. Accordingly, when a two-stroke engine of the motorcycle described in JP-B-61040864 is simply replaced by a four-stroke engine, it is quite difficult to make the compatible installation on the motorcycle.

The object of the invention is to provide a motorcycle having mounted thereon an engine assembly comprising a four-stroke engine and a belt-type CVT transmission and a length of which, in the axial direction of the cylinders, is limited.

Summary

Aspects of the invention are defined in the claims.

An embodiment of the invention may provide a straddle-type vehicle, for example a motorcycle, comprising an engine assembly provided with an output shaft, a drive wheel and a power transmission mechanism. The power transmission mechanism transmits the drive power to the drive wheel from the output shaft. The motorcycle according to the invention additionally comprises a frame body. The frame body has a vertically extending lower frame. The engine assembly comprises a four-stroke engine, a continuously variable transmission, a clutch, and an engine crankcase. The four-stroke engine includes a cylinder body and a crankshaft. The cylinder body forms a cylinder. The cylinder is arranged rearward of the lower frame with a vertically extending axis thereof. The crankshaft is arranged below the cylinder. The continuously variable transmission includes a primary pulley, a secondary pulley shaft, a secondary pulley, and an endless belt. The primary pulley is provided on the crankshaft. The shaft of the secondary pulley is arranged rearward of the crankshaft. The shaft of the secondary pulley is connected to the output shaft. The secondary pulley is provided on the secondary pulley shaft. The endless belt is wrapped around the primary pulley and the secondary pulley. The clutch is provided between the secondary pulley shaft and the output shaft. The engine crankcase supports the crankshaft, the secondary pulley shaft, and the output shaft. The crankcase of the engine is formed with an oil reservoir part, which is arranged below the crankshaft for storing a lubricating oil. The oil reservoir part is formed with a rear end thereof positioned behind a front end of the secondary pulley. The crankshaft is arranged with a shaft thereof positioned below an axis of the shaft of the secondary pulley.

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An embodiment of the invention can make a motorcycle having an engine assembly mounted thereon, which comprises a four-stroke engine and a belt-type CVT transmission and the length of which in the axial direction of the cylinder be limited.

Brief description of the drawings

Embodiments of the invention are described herein below, by way of example only, with reference to the accompanying drawings.

FIG. 1 is a side view showing an exemplary motorcycle in which the invention is incorporated.

Fig. 2 is a cross-sectional view showing the construction of an engine assembly.

Figure 3 is a side view showing the construction of the motor assembly.

Fig. 4 is a side view showing the construction of an engine assembly, a drive shaft which is arranged closer to the crankshaft than the clutch shaft is.

Figure 5 is a schematic view illustrating the positional relationship between a crankshaft axis and a secondary pulley shaft axis, a starter motor axis, and a balancer axis when viewed in side view. .

Detailed description

An example of an off-road type motorcycle 1 according to an embodiment of the invention will be described in detail hereinafter with reference to the figures. However, the straddle-type vehicle according to the invention is not limited to this type of embodiment. Also, in the context of the present application the term motorcycle is to be interpreted broadly to include other types of motorcycles and to include, for example, scooters, mopeds, and the like. Also other embodiments may include straddle vehicles other than motorcycles, for example all terrain vehicles and the like.

Fig. 1 is a side view showing an example motorcycle 1 according to the embodiment. First, a schematic construction of the motorcycle 1 will be described with reference to Figure 1. In addition, the front and rear and left and right directions in the description that follows are as seen from a user mounted on the saddle. eleven.

The motorcycle 1 comprises a frame body 2. The frame body 2 comprises a steering axle tube 3, a lower frame 4 and a support on the saddle 5. The lower frame 4 extends vertically. Specifically the lower frame 4 extends downwardly from the steering axle tube 3, bends midway and extends substantially horizontally from the middle of it. The saddle support 5 extends above the lower frame 4 and rearwardly from the steer axle tube 3. The ends of the lower frame tip 4 and the saddle support 5 are connected to each other. A support member 31 is mounted to a connection 4a of the lower frame 4 and the saddle support 5. The support member 31 extends forward from the connection 4a. A pair of left and right stirrups 30, on which the driver's feet are placed, are mounted at the tip end of the support element 31. As shown in figure 1, the stirrups 30 are positioned below a Secondary pulley 37 described hereinafter (Figure 1 depicts only secondary pulley shaft 38, to which secondary pulley 37 is mounted) as seen in side view.

A lower end of the steering axle tube 3 is connected to the front wheel 7 through a front fork 6, and so on. A rearwardly extending rear arm 8 is articulated with bearings in the vicinity of a lower end (a part slightly above the connection 4a) of the saddle support 5. More specifically, one end of the base of the rear arm 8 is articulated with bearings by a pivot shaft 5a connected to the saddle support 5. A rear wheel 9 serving as a driving wheel is rotatably mounted to one end of the tip ( rear end) of the rear arm 8.

A cover 10 is arranged above the frame body 2 to cover the frame body 2. The seat is mounted slightly rearward from the center of the cover 10.

A motor assembly 12 is disposed between the lower frame 4 and the saddle support 5. The motor assembly is mounted to the lower frame 4 and the saddle support 5. As shown in Figure 2, the motor assembly 12 is integrally composed of a four-stroke engine 13, a belt-type CVT transmission 14, a centrifugal clutch 61, a generator 29, a reduction mechanism 16, and so on. The driving force generated in the motor assembly 12 is transmitted to the rear wheel 9 (see figure 1) through a power transmission mechanism 80 (see figure 2) such as a chain, belt, and so on.

Next, the construction of the engine assembly 12 will be described mainly with reference to Fig. 2. The engine assembly 12 comprises a four-stroke engine 13, a belt-type CVT transmission 14, the

ES 2 323 905 T3 centrifugal clutch 61, reduction mechanism 16 and generator 29. Furthermore, Figure 2 omits a partial construction of reduction mechanism 16 for ease of explanation.

The engine assembly 12 is housed in a housing of the assembly 50, which serves as the engine housing. The assembly crankcase 50 comprises a crankshaft crankcase 51, a generator crankcase 54, and a transmission crankcase 55.

The crankshaft 20 is housed in the crankshaft housing 51. The crankshaft housing 51 comprises a first housing block 52 and a second housing block 53, which bear against each other in the direction of the shaft. width of the vehicle. The first crankcase block 52 is positioned to the left of a piston 23. The second crankcase block 53 is positioned to the right of the piston 23.

The transmission case 55 is mounted on the right side of the second case block 53. The transmission case 55 comprises an inner case 56 and an outer case 57. The inner case 56 is mounted on the right side of the second engine block. Case 53. The outer case 57 is mounted on the right side of the inner case 56. The outer case 57 and the inner case 56 are compartmentalized and form a belt chamber 34.

The generator crankcase 54 is removably mounted on the left side of the front half of the first crankcase block 52. The generator crankcase 54 together with the first crankcase block 52 are compartmentalized and form a generator chamber, in which the generator 29 is housed. Furthermore, the generator casing 54 is arranged opposite a primary pulley 36 in the width direction of the vehicle.

The four-stroke engine 13 comprises a crankshaft 20 extending horizontally in the width direction of the vehicle, a cylinder body 18, which forms a substantially cylindrical cylinder 18a, and a cylinder head 19. The crankshaft 20 it is housed in the crankcase 51. The crankshaft 20 is supported in the first crankcase block 52 and the second crankcase block 53 with bearings 21, 22 between them.

The cylinder 18a is connected forwardly and upwardly obliquely to the crankcase of the crankshaft 51 (see Figures 1 and 3). The cylinder 18a is disposed rearward of the lower frame 4 with an axis thereof extending vertically. The cylinder head 19 is connected to the tip end of the cylinder body 18. The piston 23 is slidably inserted into the cylinder 18a. One end of a connecting rod 24 is connected to one side of the piston 23 towards the crankshaft 20. The other end of the connecting rod 24 is connected to the crankshaft 20 by a crankpin 15 of the crankshaft arranged between a left arm of the crankshaft 20a and a right arm of the crankshaft 20b of the crankshaft 20. Thus, the piston 23 reciprocates in the cylinder 18a when the crankshaft 20 rotates.

In the cylinder head 19, a groove 19a is formed which communicates with the cylinder 18a and an intake port 19b and an exhaust port 19c (see also FIG. 3), which are communicated with the groove 19a. An intake valve 19d is arranged in the intake port 19b. On the other hand, an exhaust valve 19e is arranged in the exhaust port 19c.

A cam chain chamber 26 is formed on the left in the cylinder body 18 to provide communication between the interior of the crankcase 51 and the interior of the cylinder head 19. A cam chain 27 is disposed in the chamber of the camshaft 26. The camshaft 27 is wound around the crankshaft 20 and a camshaft 28. The camshaft 28 constitutes a part of the valve actuation mechanism 90. The intake valve 19d is actuated by the valve drive mechanism 90 which includes the camshaft 28 by which the intake port 19b is opened and closed. Also, the valve actuation mechanism 90 actuates the exhaust valve 19e whereby the exhaust port 19c opens and closes. The intake port 19b and the exhaust port 19c are opened and closed whereby the intake into the cylinder 18a and the exhaust from the cylinder 18a take place.

A spark plug 25 is mounted on the cylinder head 19. An ignition portion positioned at the tip end of the spark plug 25 is exposed within the slot 19a.

A groove, which constitutes a clutch chamber 60, is formed to the right of the rear half of the second crankcase block 53. A clutch cover 32 is tightly mounted in the groove. The clutch cover 32 is removably attached to the second crankcase block 53 by means of a stud 33.

In the second crankcase block 53, an oil supply hole 51a open to the clutch chamber 60 and an oil discharge hole 51c are provided as shown in Fig. 3. Therefore, the space in the crankcase crankshaft 51 and clutch chamber 60 communicate with each other.

A left end of the crankshaft 20 extends through the first block of the crankcase 52 until it reaches the interior of the generator crankcase 54. The generator 29 is mounted on the left end of the crankshaft 20. In particular, the generator 29 comprises a rotor 29a and a stator 29b. The rotor 29a is formed to be cylindrical in shape. Stator 29b is arranged on rotor 29a.

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Stator 29a is fixed to generator crankcase 54 so that it cannot rotate or move. On the other hand, the rotor

29a is attached to a sleeve 35, which rotates together with the crankshaft 20. Thus, when the crankshaft 20 rotates, the rotor 29a rotates relative to the stator 29b to generate electrical energy.

As shown in Figure 1, the motorcycle 1 is provided with a starter motor 71. The starter motor serves to rotate the crankshaft 20 to start the engine 13. As shown in Figure 5, the starter motor 71 is arranged such that an axis C3 thereof is positioned forwardly in an imaginary plane P1 including a cylinder axis 18a and an axis C1 of the crankshaft 20 when viewed in side view. Furthermore, the starter motor 71 is arranged such that a rear end thereof is positioned forward in the imaginary plane P1.

Also, as shown in Figure 5, the motorcycle 1 is provided with a balancer 72. The balancer serves to reduce the deflection of the weight in a direction of rotation about the axis C1 of the crankshaft 20 to smooth the rotation of crankshaft 20. Balancer 72 is connected to crankshaft 20 through a gear (not shown), and so on. Therefore, balancer 72 rotates when crankshaft 20 rotates. An axis C3 of the balancer 72 is different from the axis C1 of the crankshaft 20 as shown in Figure 5. As shown in Figure 5, the balancer 72 is arranged such that an axis C4 thereof is positioned forward. in the imaginary plane P1 when looking in side view. Furthermore, the balancer 72 is arranged so that a rear end thereof is positioned forward in the imaginary plane P1.

Also, as shown in figure 5, an additional imaginary plane P2 including the axis C1 of the crankshaft 20 and an axis C2 of the shaft of the secondary pulley 38 passes between the axis C3 of the starter 71 and the axis C4. of the balancer 72. In other words, in a vertical direction, the axis C3 of the starter motor 71 is positioned above the imaginary plane P2 while the axis C4 of the balancer 72 is positioned below the imaginary plane P2.

On the other hand, the belt type CVT transmission 14 is housed in the belt chamber 34. The belt type CVT transmission 14 comprises the primary pulley 36 and the secondary pulley 37. The secondary pulley 37 is arranged rearwardly from primary pulley 36. Secondary pulley 37 is larger in diameter than primary pulley 36.

The crankshaft 20 extends through the second crankcase block 53 and the inner crankcase 56 extends into the belt chamber 34. A right part (strictly, a part to the right of the bearing 22) of the crankshaft 20 , which reaches the belt chamber 34, constitutes a shaft of the primary pulley 20c. Primary pulley 36 is provided on primary pulley shaft 20c. In particular, according to the embodiment, the primary pulley 36 is mounted on the shaft of the primary pulley 20c. The primary pulley 36 rotates together with the primary pulley shaft 20c. However, as long as the primary pulley 36 rotates when the primary pulley shaft 20c rotates, the primary pulley is not required to be mounted directly on the primary pulley shaft 20c.

The primary pulley 36 comprises a stationary primary pulley body 36a, a moving body of the primary pulley 36b, a roller weight 44, and a cam disc 43. The stationary primary pulley body 36a is attached to the end of the right end of the primary pulley shaft 20c. The primary pulley moving body 36b is mounted to the primary pulley shaft 20c to the left of the stationary primary pulley body 36a. The moving body of the primary pulley 36b is axially movable relative to the shaft of the primary pulley 20c. The stationary body of the primary pulley 36a and the moving body of the primary pulley 36b constitute a groove of the belt 36c, which is of variable width.

The cam disc 43 is further disposed to the left of the moving body of the primary pulley 36b. The cam disc 43 is fixed to the shaft of the primary pulley 20c. A gap between the moving body of the primary pulley 36b and the cam disc 43 becomes smaller radially outward. Roller weight 44 is disposed between the moving body of primary pulley 36b and cam disc 43. Roller weight 44 is arranged to be radially movable inward and outward.

On the other hand, the shaft of the secondary pulley 38 is arranged in the rear half of the transmission case 55. The shaft of the secondary pulley 38 is arranged rearward of the shaft of the primary pulley 20c. As shown in FIG. 3, the crankshaft 20 is arranged so that an axis thereof is positioned below an axis of the secondary pulley 38 shaft.

The secondary pulley shaft 38 extends through the inner casing 56 and the clutch cover 32 to extend into the clutch chamber 60. The secondary pulley shaft 38 is mounted on the clutch cover 32 with a bearing 39 between them. The secondary pulley 37 is provided on the secondary pulley shaft 38 within the belt chamber 34. In particular, according to the embodiment, the secondary pulley is mounted on the secondary pulley shaft 38. The secondary pulley 37 rotates together with the secondary pulley shaft 38. However, provided that the secondary pulley 37 rotates When the secondary pulley shaft 38 rotates, the secondary pulley is not required to be mounted directly on the secondary pulley shaft 38.

The secondary pulley 37 comprises a stationary secondary pulley body 37a and a displacing body of the secondary pulley 37b. The stationary body of the secondary pulley 37a is fixed to the shaft of the secondary pulley in the belt chamber 34. The displacing body of the secondary pulley 37b is mounted on the shaft of

ES 2 323 905 T3 the secondary pulley 38 to the right of the stationary body of the secondary pulley 37a. The moving body of the secondary pulley 37b can be axially displaced relative to the shaft of the secondary pulley 38. The stationary body of the secondary pulley 37a and the moving body of the secondary pulley 37b constitute a groove of the belt 37c , which is of variable width.

A substantially cylindrical spring latch 47 is attached to the right tip end of the secondary pulley shaft 38. A compression helical spring 45 is disposed between the spring latch 47 and the displacing body of the secondary pulley. 37b. The deflection of the helical compression spring 45 biases the moving body of the secondary pulley 37b to the left, that is, towards the stationary body of the secondary pulley 37a.

An endless belt 41 having a substantially trapezoidal cross section is wound around the belt groove 37c of the secondary pulley 37 and the belt groove 36c of the primary pulley.

36. Therefore, when the primary pulley 36 rotates together with the crankshaft 20, the torque thereof is transmitted to the secondary pulley 37 through the endless belt 41. Consequently, the secondary pulley shaft 38 rotates. also together with the secondary pulley 37. Furthermore, the endless belt 41 may comprise, for example, a resin block belt.

As shown in Figure 1, a center (center of the shaft of the secondary pulley 38) of the secondary pulley 37 is positioned higher than the center (center of the shaft of the primary pulley 20c) of the primary pulley 36 That is, the belt type CVT transmission 14 is arranged in a rearward and upwardly extending manner. The pivot shaft 5a, to which the tip end of the rear arm 8 is mounted, is provided in a position lower than the center of the secondary pulley 37.

The secondary pulley shaft 38 is connected to an output shaft 16b through the centrifugal clutch 61, and so on. In particular, a part (the part positioned in the clutch chamber 60) of the secondary pulley shaft 38 to the left of the clutch cover 32 constitutes a clutch shaft 40. The centrifugal clutch 61 is mounted to the clutch shaft 40 Furthermore, the reduction mechanism 16 is connected to the centrifugal clutch 61. The centrifugal clutch 61 provides a connection or a disconnection between the secondary pulley shaft 38 and the reduction mechanism 16 in accordance with the rotational speed of the secondary pulley shaft 38 (the clutch shaft 40).

The centrifugal clutch 61 comprises a clutch hub 61a connected to the reduction mechanism 16, a substantially cylindrically shaped clutch housing 61b, and a roller weight 61c. Roller weight 61c is arranged to allow radially inward and outward movement. The clutch housing 61b is fixed to the clutch shaft 40. Therefore, the clutch housing 61b rotates together with the clutch shaft 40 (the secondary pulley shaft 38). Clutch housing 61b comprises a plurality of clutch discs 61d arranged at substantially equal intervals relative to each other. The mutually adjacent clutch discs 61d are at variable intervals.

The clutch hub 61a is arranged in the clutch housing 61b. Clutch hub 61a is rotatable relative to clutch shaft 40. Clutch hub 61a comprises a plurality of friction discs 61e arranged at substantially equal intervals relative to each other. The mutually adjacent friction discs 61a are at variable intervals.

When the shaft of the secondary pulley 38 rotates at a small rotational speed, the clutch discs 61d and the friction discs 61e separate from each other. The clutch housing 61b and the clutch hub 61a are not connected to each other. Therefore, the torque of the secondary pulley shaft 38 is not transmitted to the reduction mechanism 16.

On the other hand, when the shaft of the secondary pulley 38 is rotating at a high speed, the roller weight 61c is shifted radially outward. Thus, the distance between adjacent friction discs 61e is reduced. The respective clutch discs 61d and the respective friction discs 61e are arranged in a pressure contact state. Accordingly, the clutch housing 61b and the clutch hub 61a are arranged in the connected state, so that the torque of the secondary pulley shaft 38 is transmitted to the reduction mechanism 16. In detail, the clutch hub 61a and the reduction shaft 16a of the reduction mechanism 16 mesh with each other and the clutch hub 61a rotates whereby the reduction shaft 16a also rotates. The torque transmitted to the reduction shaft 16a exits from the output shaft (not shown) of the reduction mechanism 16 to be transmitted to the rear wheel 9 (see FIG. 1).

According to the embodiment, the reduction shaft 16a of the reduction mechanism 16 is arranged at a position more distant from the crankshaft 20 than from the clutch shaft 40, that is, backwards as shown in Figures 2 and 3. In other words, the clutch shaft 40, to which the wet-type centrifugal clutch 61 is mounted, is disposed closer to the crankshaft 20 than the reduction shaft 16a is. A construction is provided in which there is substantially no rotary shaft preventing oil supply to the clutch shaft 40 between the crankshaft 20 and the clutch shaft 40. In particular, according to the embodiment, no rotary shaft is arranged between the crankshaft 20 and the clutch shaft 40.

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Subsequently, a construction, in which a lubricating oil is supplied to the clutch shaft 40, according to the embodiment, will be described with reference to Figures 2 and 3. As shown in Figure 3, an oil reservoir part 51b is provided at the bottom of the crankcase 51 for storing lubrication oil. In particular, the oil reservoir portion 51b is formed to extend rearwardly from a front end of the secondary pulley 37 from in front of a front end of the primary pulley 36. More specifically, a rear end of the oil reservoir portion 51b is positioned rearward of the shaft axis than the secondary pulley 38. That is, according to the embodiment, the oil reservoir part 51b is formed globally below the primary pulley 36 and the secondary pulley 37.

A lubricating oil stored in the oil reservoir part 51b is supplied to a connection 42 of the crankshaft 20 and the connecting rod 24 by an oil pump 70, which is arranged as a lubricating oil supply mechanism in the oil tank part 51b in crankcase 51 crankshaft. In particular, the lubricating oil drawn in by the oil pump 70 is guided into one or a plurality of oil supply passages 20d, which are substantially circular in shape as seen in plan view and open to the extreme left surface. of the crankshaft 20, to be supplied to the connection 42 through the oil supply passage (s) 20d.

The lubricating oil supplied to the connection 42 spreads from the connection 42 as the crankshaft 20 rotates. In the second block of the crankcase 53, an oil supply port 51a is provided to guide a lubricating oil, which is spreads as crankshaft 20 rotates into clutch chamber 60 to supply clutch shaft 40. In particular, as shown in figure 3, the oil supply hole 51a is formed in the second block of the crankcase 53 so that a tangent line L1 tangent to both, to the rolling circle 15a of the crank pin of the crankshaft 15 and an outer ring of the oil supply port 51a, is positioned above a lower end A of the clutch shaft body 40 when viewed in side view. Furthermore, the tangent line L1 is more specifically a tangent line, which is tangent to the lower part of the rolling circle 15a of the crankshaft journal 15 and an upper part of the oil supply hole 51a and passes between the hole oil supply valve 51a and the rolling circle 15a to extend rearwardly and obliquely upward. Furthermore, at least a part of the oil supply hole 51a is formed in the second block of the crankcase 53 so that it is positioned above the straight line L10 which passes through the axis C1 of the crankshaft 20 and an axis C2 of the clutch shaft 40. The crankshaft 20 and the clutch shaft 40 are arranged such that parts thereof face each other with the oil supply port 51a between them.

The lubricating oil introduced into the clutch chamber 60 from the oil supply port 51a is supplied to the clutch shaft 40 and thereafter returns again to the oil reservoir part 51b from the oil discharge port 51c provided. down and slightly rearward of the second crankcase block 53.

Furthermore, the oil discharge hole 51c is positioned above the lowermost point of the rolling circle 15a of the connection 42 in a vertical direction when viewed from the side view. Furthermore, the discharge hole 51c is positioned in the same position as the crankshaft 20, or above the crankshaft 20 in the vertical direction when viewed from the side view.

As previously described herein, the motor assembly 12 according to the embodiment comprises the primary pulley 36 and the secondary pulley 37 arranged rearwardly from the primary pulley 36. Therefore, the motor assembly 12 is larger. in length than an ordinary engine assembly of a type of transmission called manual. According to the embodiment, taking this characteristic into account, the oil reservoir part 51b is formed to be longer in the longitudinal direction so that it extends rearwardly from the front end of the secondary pulley 37 as shown in figure 3. In this way, the oil tank part 51b normally arranged below the crankshaft 20 is formed to be longer in the longitudinal direction whereby it is possible to secure a volume for the oil tank part 51b and shorten the length. length of the oil reservoir part 51b in the axial direction of the cylinder 18a. Therefore, the length L of the motor assembly 12 in the axial direction of the cylinder 18a is limited.

Also, according to the embodiment, since the cylinder 18a is arranged so that an axis of the cylinder 18a extends vertically, the length of the motor assembly 12 in the longitudinal direction is also limited.

By the way, with the belt type CVT transmission 14, the secondary pulley 37 is larger in diameter than the primary pulley 36. Therefore, when the axis C1 of the crankshaft 20 provided with the primary pulley 36 and the axis C2 of the shaft of the secondary pulley 38 provided with the secondary pulley 37 are arranged to be horizontal, a lower end of the secondary pulley 37 is positioned below a lower end of the primary pulley 36. Consequently, the length L of the motor assembly 12 is lengthened in the axial direction of the cylinder 18a.

On the contrary, according to the embodiment, the axis C1 of the crankshaft 20 is positioned below the axis C2 of the shaft of the secondary pulley 38. In other words, the axis C2 of the shaft of the secondary pulley 38 is positioned above the axis C1 of the crankshaft 20. Therefore, the length L of the motor assembly 12 is shortened in the axial direction of the cylinder 18a. The axis C2 of the shaft of the secondary pulley 38 is preferably positioned in substantially the same position as the axis C1 of the crankshaft 20, or above the axis C1 of the shaft of the

ES 2 323 905 T3 crankshaft 20 in the axial direction of cylinder 18a. Accordingly, the length L of the motor assembly 12 in the axial direction of the cylinder 18a can be further effectively decreased.

Also, the embodiment has a higher torque at low speed and great comfort due to the adoption of the four-stroke engine 13.

Furthermore, for example, in the case where the axis C3 of the starter motor 71 is positioned rearward of the imaginary plane P1 and the axis C4 of the balancer 72 is positioned rearward of the imaginary plane P1, the starter motor 71, the Balancer 72 and secondary pulley 37 interfere with each other, so that it is difficult to make C1 axis of crankshaft 20 lower than axis C2 of secondary pulley 38 shaft.

On the contrary, according to the embodiment, as shown in Fig. 5, the starter motor 71 is arranged so that its axis C3 is arranged forward of the imaginary plane P1 when viewed in side view. Also, the balancer 72 is arranged such that its axis C4 is positioned forward of the imaginary plane P1 when viewed in side view. Therefore, the starter 71, balancer 72 and secondary pulley 37 are prevented from interfering with each other. Accordingly, it is possible to easily make the axis C1 of the crankshaft 20 lower than the axis C2 of the shaft of the secondary pulley 38.

Also, since the starter motor 71 and balancer 72 are not present on the axis of the cylinder 18a, the length of the motor assembly 12 in the axial direction of the cylinder 18a is relatively reduced.

Also, for example, in the case where both the starter 71 and the balancer 72 are positioned above the imaginary plane P2 and in the case where both the starter 71 and the balancer 72 are positioned below the imaginary plane P2, the starter 71 and balancer 72 are aligned in one direction, in which the primary pulley 36 and secondary pulley 37 are arranged. Therefore, the length of the motor assembly 12 in a direction, in which the primary pulley 36 and the secondary pulley 37 are arranged, is relatively increased. Consequently, the length of the motor assembly 12 in the longitudinal direction becomes relatively large.

On the contrary, according to the embodiment, in the vertical direction, the axis C3 of the starter motor 71 is positioned above the imaginary plane P2 while the axis C4 of the balancer 72 is positioned below the imaginary plane P2. Therefore, the starter 71 and balancer 72 are not aligned in that direction, in which the primary pulley 36 and secondary pulley 37 are disposed. Therefore, the length of the motor assembly 12 in that direction, in which the primary pulley 36 and secondary pulley 37 are arranged, can be relatively shortened. Consequently, the length of the motor assembly 12 in the longitudinal direction becomes relatively small.

According to the embodiment, as shown in Figures 2 and 3, the oil supply port 51a and the oil discharge port 51c are formed in the second crankcase block 53. Therefore, the clutch chamber 60 It is in communication with the inside of the crankcase 51. Accordingly, when the motor assembly 12 vibrates or fluctuates to cause the lubricating oil in the oil tank part 51b to splash, or cause the oil level of the lubricating oil to fluctuate, there is a danger that a large amount of oil Lubricant flows into clutch chamber 60 through oil supply port 51a and oil discharge port 51c. Accordingly, there is a danger that an excess amount of lubricating oil is supplied to the centrifugal clutch 61. When an excess amount of lubricating oil is supplied to the centrifugal clutch 61, a problem is caused that a loss is generated in the transmission. of the energy in the centrifugal clutch 61 by the viscous resistance of the lubricating oil. Also, a problem is caused that the rotational speed of the centrifugal clutch 61 is reduced. In addition, the problem is also caused that the lubricating oil rises in temperature and the lubricating oil degrades in lubricating ability.

As previously described herein, according to the invention, however, the axis C2 of the shaft of the secondary pulley 38 is positioned above the axis C1 of the crankshaft 20 when viewed in side view. That is, the belt type CVT transmission 14 is arranged in a rearwardly and upwardly extending manner. In other words, as shown in Figures 1 and 3, the straight line L10 passing through the center of the primary pulley shaft 20c and the center of the secondary pulley shaft 38 rises rearwardly as seen in view. in plant. Therefore, as shown in Fig. 3, the secondary pulley shaft 38, on which the centrifugal clutch 61 is mounted, is positioned relatively higher than the oil level S of the lubricating oil in the part oil tank 51b. Also, the oil supply hole 51a and the oil discharge hole 51c are also formed at positions relatively higher than the oil level S.

Therefore, even when the motor assembly 12 vibrates or fluctuates to cause the lubricating oil in the oil reservoir part 51b to splash, or to cause the lubricating oil level to fluctuate, the lubricating oil is prevented from entering the chamber. of clutch 60 from oil discharge port 51c. Also, lubricating oil is prevented from being supplied in excess to the centrifugal clutch 61. Accordingly, it is possible to suppress the loss in power transmission in the centrifugal clutch 61. The centrifugal clutch 61 can be prevented from reducing its rotational speed. Additionally, it is possible to prevent the lubricating oil from increasing its temperature. Accordingly, it is possible to prevent the lubricating oil from reducing its lubricating ability. Furthermore, the construction is especially effective in a straddle vehicle, which rolls on relatively uneven ground such as a mud track, etc., such as the off-road type motorcycle according to the embodiment.

ES 2 323 905 T3

In order to especially effectively suppress the ingress of lubricating oil into the clutch chamber 60 from the oil discharge port 51c, the oil discharge port 51c is preferably positioned above the lowest point of the rolling circle 15a of the connection 42 in the vertical direction when looking in side view. Furthermore, the oil discharge hole 51c is preferably positioned in the same position as the crankshaft 20, or above the crankshaft 20 in the vertical direction when viewed from the side view.

In this way, according to the embodiment, while effectively preventing the lubricating oil from being excessively supplied to the centrifugal clutch 61, the lubricating oil required for the centrifugal clutch 61 is efficiently supplied as described hereinafter. In particular, according to the embodiment, since the lubricating oil is supplied to the centrifugal clutch 61 as the crankshaft 20 rotates, the crankshaft 20 and the clutch shaft 40 rotate at high speed per unit of time and When a relatively large quantity of lubricating oil becomes necessary, a large additional quantity of lubricating oil is supplied to the centrifugal clutch 61, so that the seizure of the centrifugal clutch 61 is safely suppressed.

For example, with the construction depicted in Figure 4, a reduction shaft 216a prevents lubricating oil introduced into the clutch chamber 260 from being supplied to the clutch shaft 240. Specifically, as depicted in Figure 4, since reduction shaft 216a is arranged closer to crankshaft 220 than to clutch shaft 240. Therefore, most of the lubricating oil introduced into the clutch chamber 260 from an oil supply port 251a collides with the reduction shaft 216a. With the construction shown in Fig. 4, a part of the lubricating oil striking the reduction shaft 216a to spread it is only supplied to the clutch shaft 240 so that it is difficult to efficiently supply a lubricating oil to the clutch shaft 240.

On the contrary, the reduction shaft (transmission shaft) 16a is arranged rearward of the clutch shaft 40 according to the embodiment as shown in Figures 2 and 3. That is, the clutch shaft 40 is arranged closer to the crankshaft 20 than to the reduction shaft 16a. Accordingly, the lubricating oil supplied from the connection 42 is efficiently supplied to the clutch shaft 40 and the centrifugal clutch 61 without being obstructed by the reduction shaft 16a. In particular, according to the embodiment, a construction is realized in which there is no rotary shaft between the crankshaft 20 and the clutch shaft 40 and preferably from the point of view of efficient supply of lubricating oil to the clutch shaft 40 and centrifugal clutch 61.

As described hereinabove, according to the embodiment, since the efficient supply of lubricating oil to the centrifugal clutch 61 is realized, the seizure of the centrifugal clutch 61 is effectively suppressed. Also, it is possible to make the hole of oil supply 51a is relatively small in size. Furthermore, the oil pump 70 is not required to have a considerably large oil supply capacity per unit of time and therefore it is possible to make the oil pump 70 and consequently the motor assembly 12 small in size and light in weight. .

Also, arranging the motor assembly 12 so that a center (center of secondary pulley shaft 38) of secondary pulley 37 is positioned above the center (center of primary pulley shaft 20c) of primary pulley 36, it is possible to shorten the length of the motor assembly 12 in the longitudinal direction. Therefore, it is possible to arrange the saddle support 5 further forward. Accordingly, it is also possible to arrange the pivot shaft 5a further forward, so that it is possible to lengthen the rear arm 8. Accordingly, the kinematic behavior of the motorcycle 1 can be improved.

To improve the kinematic behavior of the motorcycle 1, the pivot shaft 5a is preferably positioned below the center of the secondary pulley 37 when viewed from the side. This is so because the housing of the assembly 50 and the pivot shaft 5a can be prevented from interfering with each other, since it is possible to arrange the pivot shaft 5a further forward.

While the embodiment has been described with respect to an example, in which in the vertical direction the axis C3 of the starter motor 71 is positioned above the imaginary plane P2 while the axis C4 of the balancer 72 is positioned below the plane imaginary P2. However, the invention is not limited to this. The axis C3 of the starter motor 71 can be positioned below the imaginary plane P2 while the axis C4 of the balancer 72 can be positioned above the imaginary plane P2.

As used herein, the term "vertically extended" is not limited only to being vertically extended in the strict sense. The expression includes the case where it extends obliquely at an angle of ± 45 ° or less from the vertical direction.

The invention finds application in a straddle-type vehicle provided with a continuously variable belt-type transmission. In particular, the invention is useful for a straddle-type vehicle having a belt-type continuously variable transmission and a relatively large displacement.

ES 2 323 905 T3

Description of reference numbers and signs

1. motorcycle

2. body frame

3. steering axle tube

Four. lower frame

5. saddle support

5th. pivot shaft

8. rear arm

9. rear wheel

12. motor assembly

13. motor

14. Continuously Variable Belt Type Transmission (CVT)

fifteen. crankshaft journal

15a. rolling circle

16. reduction mechanism

16th. reduction tree

twenty. crankshaft

20c. shaft than primary pulley

20d. oil supply step

30. stapes

36. primary pulley

37. secondary pulley

38. secondary pulley shaft

40. clutch shaft

fifty. crankcase of the set

51. crankcase crankshaft

51a. oil supply hole

51b. oil tank part

51c. oil discharge hole

54. generator crankcase

55. transmission crankcase

60. clutch chamber

61. centrifugal type clutch

70. oil pump.