Title of Invention

POWER UNIT

Abstract

To provide a power unit which has a small dimension in the width directions, and which is suitable for being mounted on a motorcycle. [Solving Means] Provided is a power unit configured of an engine and a belt-type continuously variable transmission which is provided as being separated from the engine by a wall of the crankcase housing the crankshaft of the engine, and which changes the torque of the crankshaft that sticks out of the wall of the crank case. The belt-type continuously variable transmission has a drive pulley to which the torque of the crankshaft is inputted, a driven pulley that is provided in parallel to the drive pulley, and a drive belt looped between the drive pulley and the driven pulley and transmitting the torque of the drive pulley to the driven pulley. Furthermore, in the configuration of the power unit, a rotation shaft (an oil-pump rotation shaft) of an oil pump for supplying oil to each portion of the engine is provided at a position offset from a supporting shaft of the drive pulley, that is, a drive-pulley shaft, and the oil pump is driven by an oil-pump drive gear provided on the drive-pulley shaft. [Selected Drawings] Fig. 3.

Full Text

[Document Name] Specification [Title of the Invention] POWER UNIT [Technical Field of the Invention] [0001] The present invention relates to a power unit equipped with an engine and a belt-type continuously variable transmission that changes the torque of the engine. [Background Art] [0002] A power unit of a type shown, for example, in the below-mentioned patent document is known as a power unit equipped with an engine and a belt-type continuously variable transmission that changes the torque of the engine. In this form of power unit, a drive pulley of the belt-type continuously variable transmission is provided on the crankshaft of the engine. The driven pulley of the belt-type continuously variable transmission, on the other hand, is provided on a driven-pulley shaft, which is provided in parallel to the crankshaft, While the crankshaft is supported by the crank case, one of its sides extends within a mission case and the end portion is supported by a bearing attached to the mission case. [0003] In the above-mentioned power unit, an oil pump is provided outside the mission case, and is driven directly by the crankshaft. This configuration has the following advantage. The belt-type continuously variable transmission has a common shaft that functions as a drive-pulley shaft as well as the crankshaft, while the crankshaft directly drives the oil pump. As a result, use of this configuration can reduce the number of parts. [Patent Document 1] Japanese Utility Model Examined Publication No. Hei 4-41204. [Disclosure of the Invention] [Problems to be Solved by the Invention] [0004] Such a configuration as of the above-mentioned conventional power unit has a problem. Specifically, in the conventional power unit the drive pulley is provided on the crankshaft and the oil pump is provided at an end portion of the crankshaft. This leads to a larger lateral dimension of the entire power unit. This power unit mounted on a motorcycle as a transverse-type engine, that is, the engine arranged in a lateral direction of the vehicle body, has the following problems. The power unit thus mounted renders the bank angle small. In addition, a motorcycle with the above-mentioned power unit mounted thereon has a larger dimension in the width directions of the vehicle body, which restricts a range of the movement of the legs of the driver straddling the motorcycle. [0005] The present invention has been made, taking the above-mentioned problems into consideration. An object of the present invention is to provide a power unit with a configuration which can make the dimension in the width directions small and which is suitable for being mounted on a motorcycle. [Means for Solving the Problem] [0006] A power unit of the present invention is made up of an engine and a belt-type continuously variable transmission. The belt-type continuously variable transmission is placed as being separated from the engine by a wall of a crank case which houses the crankshaft of the engine (for example, by a right-side wall lla of a crank case 11 in the embodiment) . The beIt-type continuously variable transmission changes the torque of the crankshaft which sticks out of the wall of the crank case. In the power unit, the belt-type continuously variable transmission includes a drive pulley, a driven pulley and a drive belt. To the drive pulley, the torque of the crankshaft is inputted. The driven pulley is provided in parallel to the drive pulley. The drive belt is looped between the drive pulley and the driven pulley, and transmits the torque of the drive pulley to the driven pulley. A rotation shaft of an oil pump (for example, an oil-pump rotation shaft 91 in the embodiment) , which supplies oil to each of the portions of the engine, is provided as being offset from a supporting shaft of the drive pulley (for example, an drive-pulley shaft 44 in the embodiment) , and the oil pump is driven by an oil-pump drive gear provided on the supporting shaft of the drive pulley. [0007] In the power unit with this configuration, the supporting shaft of the drive pulley and the crankshaft are preferably made as separate bodies and placed in parallel to each other. In addition, the supporting shaft of the drive pulley is preferably driven by a drive-pulley-supporting-shaft drive gear (for example, a drive-pulley-shaft drive gear Gl in the embodiment) . Furthermore, the crankshaft is preferably placed between the supporting shaft of the drive pulley and the supporting shaft of the driven pulley (for example, a driven-pulley shaft 45 in the embodiment). [0008] A second power unit of the present invention includes an engine and a belt-type continuously variable transmission. The belt-type continuously variable transmission is placed as being separated from the engine by a wall of a crank case which houses the crankshaft of the engine. The belt-type continuously variable transmission changes the torque of the crankshaft which sticks out of the wall of the crank case. In the power unit, the belt-type continuously variable transmission includes a drive pulley, a driven pulley and a drive belt. To the drive pulley, the torque of the crankshaft is inputted. The driven pulley is provided in parallel to the drive pulley. The drive belt is looped between the drive pulley and the driven pulley, and transmits the torque of the drive pulley to the driven pulley. A clutch mechanism for transmitting the torque of driven pulley to the supporting shaft of the driven pulley is provided on the supporting shaft of the driven pulley and at the position between the driven pulley and the wall of the crank case. In addition, an oil pump for supplying oil to each of the portions of the engine is driven by an oil-pump drive gear attached on a shaft different from the crankshaft (for example, a drive-pulley shaft 44 in the embodiment). [Effects of the Invention] [0009] In the power unit of the present invention, the rotation shaft of the oil pump is provided at a position offset from the supporting shaft of the drive pulley, and the oil pump is driven by the oil-pump drive gear provided on the supporting shaft of the drive pulley. As a result, the power unit of the present invention has a smaller dimension of the entire body of the power unit in the width directions than a power unit with an oil pump being provided at the end portion on the supporting shaft of the drive pulley. Consequently, the power unit of the present invention is suitable for being mounted on a motorcycle. In addition, the rotation speed of the oil pump can be adjusted easily by the gear ratio between the oil-pump drive gear and a gear (an oil-pump driven gear) which is provided on the rotation shaft of the oil pump, and which meshes with the oil-pump drive gear. Consequently, an advantage of the power unit of the present invention is that the oil pump is prevented from rotating so rapidly that such an inconvenience as getting air bubbles trapped in the oil would take place. [0010] Here, in the configuration of this power unit, the supporting shaft of the drive pulley and the crankshaft are separate bodies, these two shafts are placed in parallel to each other, and the supporting shaft of the drive pulley is driven by a drive-pulley-supporting-shaft drive gear provided on the crankshaft. This makes it possible to cause the power unit with the above-described configuration to have a smaller dimension in the front to rear directions than a power unit with a configuration in which a single shaft functions as the crankshaft and as the supporting shaft of the drive pulley (i.e. a power unit with a configuration in which the drive pulley is placed on the crankshaft). This is because the drive pulley can be arranged more closely to the crankshaft in the power unit of the present invention. [0011] Additionally, the crankshaft is placed between the supporting shaft of the drive pulley and the supporting shaft of the driven pulley. This arrangement allows an end portion of the crankshaft to be placed in a space between the supporting shaft of the drive pulley and the supporting shaft of the driven pulley. This renders the dimension of the entire body of the power unit in the front to rear directions smaller than otherwise. [0012] In a second power unit of the present invention, the oil pump is driven by the oil-pump drive gear attached on a shaft different from the crankshaft. Suppose a case where a clutch mechanism transmitting the torque of the driven pulley to the supporting shaft of the driven pulley is provided on the supporting shaft of the driven pulley and at a position between the driven pulley and the wall of the crankcase. In such a case, the dimension of the entire body of the power unit in the width directions can be made smaller than otherwise, and the power unit becomes suitable for being mounted on a motorcycle. Such an arrangement of the clutch mechanism may eliminate a space where the oil-pump drive gear can be provided on the crankshaft. Even in this case, provision of the oil-pump drive gear on a shaft different from the crankshaft enables the oil pump to be driven. In addition, the oil pump is driven not directly by the crankshaft but indirectly by the crankshaft via a gear. As a result, the rotation speed of the oil pump is adjusted easily. [Best Mode for Carrying Out the Invention] [0013] Explanations of a preferred embodiment of the present invention will be given below by referring to the drawings. Figs. 1 to 3 illustrate a power unit 2 related to an embodiment of the present invention. The power unit 2 is mounted, for example, on a motorcycle as a transverse-type engine. This power unit 1 has an engine 20, a belt-type continuously variable transmission 40, a starter clutch 50, an output shaft 60, a kick starter spindle 10, gears and the like linked with the kick starter spindle 70. These are housed in a casing 10, also included in the power unit 1. The casing 10 is configured of a crank case 11, a mission case 12, a mission cover 13 and an alternator cover 14. In addition, an alternator 80, an oil pump 90 and the like are attached in the casing 10 (see Figs, 2 and 3) . Note that the directions mentioned in the description here are the directions seen from the driver riding on the motorcycle♦ [0014] A piston 22 is provided in the cylinder 21 of the engine 20 and is capable of slidingly traveling freely. The upper end portion of a connecting rod 24 is attached to the piston 22 with a piston pin 23. The lower end portion of the connecting rod 24 is attached to the crankshaft 26 with a crankpin 25. The crankshaft 26 extends within the crankcase 21 in the lateral directions. Here, the crankshaft 26 is supported by bearings Bl and B2 respectively attached to the walls lla and 22Jb of the crankcase 11, and is capable of rotating freely. The right end portion of the crankshaft 26 extends to the right, penetrating the right-side wall lla of the crankcase 11. A drive-pulley-shaft drive gear Gl is fixed to the crankshaft 26 at the right end portion of the crankshaft 26 (the portion sticking out of the crankcase 11) . On the other hand, the left end portion of the crank shaft 26 extends to the left, penetrating the left-side wall lib of the crankcase 11. [0015] A mission case 12 is joined to the right side of the crankcase 11. To the right side of the mission case 12, a mission cover 13 is further joined. In a space surrounded by the mission case 12 and the mission cover 13 (at the position outside the crankcase 11 beyond the right-side wall lla of the crank case 11) , a belt-type continuously variable transmission 40 is placed. The belt-type continuously variable transmission 40 changes the torque of the crankshaft 26. The belt-type continuously variable transmission 40 has a drive pulley 41 and a driven pulley 42 which are disposed with their respective rotation axes AX1 and AX2 being parallel to each other. The belt-type continuously variable transmission 40 also has a drive belt (V-belt) 43 looped between the drive pulley 41 and the driven pulley 42. [0016] A drive-pulley shaft 44 is a supporting shaft of the drive pulley 41. The drive-pulley shaft 44 extends in the lateral directions, penetrating the drive pulley 41. The drive-pulley shaft 44 is supported, as being capable of rotating freely, by a bearing B3, a bearing B4 and a needle bearing NB, which are respectively attached to a wall 12a of the mission case 12, to the mission cover 13 and the right-side wall lla of the crank case 11. In a sector between the bearing B3 (i.e. the wall 12a of the mission case 12) and the right-side wall lla of the crank case 11, a drive-pulley-shaft driven gear G2, which meshes with the above-mentioned drive-pulley-shaft drive gear Gl, and an oil-pump drive gear Gl, which drives an oil pump 90 to be described later, are provided. Both of the gears G2 and Gl are fixed to the drive-pulley shaft 44. The drive-pulley shaft 44 is placed parallel to the crankshaft 26. When the crankshaft 26 rotates, the torque is transmitted from the crankshaft 26, via drive-pulley-shaft drive gear Gl and the drive-pulley-shaft driven gear G2, to the drive-pulley shaft 44. [0017] A driven-pulley shaft 45 is a supporting shaft of the driven pulley 42. The driven-pulley shaft 45 extends in lateral directions penetrating the driven pulley 42, and extends further to the left, penetrating the wall 12a of the mission case 12 and the right-side wall lla of the crank case 11. The driven-pulley shaft 45 is supported, as being capable of rotating freely, by a bearing B5, a bearing B6, and a bearing Bl, which are respectively attached to the wall lla and to the lib of the crank case 11, and to the mission cover 13. The driven-pulley shaft 45 is placed parallel to the drive-pulley shaft 44, so that the crankshaft 26, the drive-pulley shaft 44 and the driven-pulley shaft 45 are all parallel to one another. Here, as seen from the Figs. 1 and 2, the crankshaft 26 is placed between the drive-pulley shaft 44 and the driven-pulley shaft 45. [0018] The drive pulley 41 is made up of a fixed half 41a that is fixed on the drive-pulley shaft 44 and a movable half 41b provided at the right of the fixed half 41a. The movable half 41b is capable of moving in an axial direction of the drive-pulley shaft 4 4 relatively to the fixed half 41a. A guide member 41c is fixedly provided on the drive-pulley shaft 44 and at the right of the movable half 41b, and the guide member 41c is fixed to the drive-pulley shaft 44. A plurality of weight rollers 41d are housed in a space between the movable half 41b and the guide member 41c. Here, when the drive pulley 41 rotates, each weight roller 41d, due to the centrifugal force acting thereon, moves to a direction away from the axis of the drive-pulley shaft 41. The weight rollers 41b moving in an above-mentioned way press to move the movable half 42b towards the fixed half 41a (to the left). [0019] The driven pulley is made up of a fixed half 42a and a movable half 42b provided at the left of the fixed half 42a. The fixed half 42a is provided on the driven-pulley shaft 45 and is capable of rotating relatively to the driven-pulley shaft 45. The movable half 42b is capable of moving, relatively to the fixed half 42af in an axial direction of the driven-pulley shaft 45. The movable half 42b is biased towards the fixed half 42a (to the right) by a spring 42c provided, as being compressed, at the left of the movable half 42b and between the movable half 42b and a clutch inner 51 fixed to the fixed half 42a. [0020] The drive belt 43 is a rubber belt with its side surfaces forming a V-shape and is looped between a pulley groove of the drive pulley 41 (a V-shaped groove formed of a pulley slope of the fixed half 41a and a pulley slope of the movable half 41b) and a pulley groove of the driven pulley 42 (a V-shaped groove formed of a pulley slope of the fixed half 42a and a pulley slope of the movable half 42b). An adequate amount of frictional force acts between the V-shaped side surfaces of the drive belt 43 and the pulley groove of the drive pulley 41, and between the V-shaped side surfaces of the drive belt 43 and the pulley groove of the driven pulley 42. As a result, the torque of the engine 20 (or the torque of the crankshaft 26) inputted to the drive-pulley shaft 44 is transmitted from the drive pulley 41, via drive belt 43, to the driven pulley 42. [0021] When the drive pulley 41 does not rotate, and when the drive pulley rotates slowly, the weight rollers 41d, provided in the drive pulley 41, are positioned closely to the drive-pulley shaft 44. At this time, the movable half 42b of the driven pulley 42 is positioned, as being biased by the spring 42c, closely to the fixed half 42a of the driven pulley 42. As a result, the pulley groove of the drive pulley 41 is in a wider state and the pulley groove of the driven pulley 43 is in a narrower state. In this case, the radius of contact of the drive belt 43 to the drive pulley 41 becomes small and the radius of contact of the drive belt 43 to the driven pulley 42 becomes large, which makes the belt-type continuously variable transmission 4 0 have a reduction ratio larger than one. In other words, the belt-type continuously variable transmission 40 becomes in the low-speed (low-gear) state. [0022] When the drive pulley 41 increases its rotation speed from the speed in the above-mentioned low-speed state, the centrifugal force acting on the weight rollers 41d moves the weight rollers 41d away from the drive-pulley shaft 44. The above movement of the weight rollers 41d pressing the movable half 41b of the drive pulley 41 moves the movable half 41b towards the fixed half 41a. This movement of the movable half 41b narrows the width of the pulley groove of the drive pulley 41, with the length of the drive belt 43 being invariable, so that the drive belt 43 moves the movable half 42b of the driven pulley 42 away from the fixed half 42a (in a direction opposite the biasing direction of the spring 42c), which widens the width of the pulley groove of the driven pulley 42. As a result, the radius of contact of the drive belt 43 to the drive pulley 41 becomes approximately equal to the radius of contact of the drive belt 43 to the driven pulley 42, and the belt-type continuously variable transmission 40 has a reduction ratio approximately equal to one. In other words, the transmission 40 becomes in the medium-speed state. [0023] When the drive pulley 41 further increases its rotation speed from the speed in the above-mentioned medium-speed state, the centrifugal force acting on the weight rollers 41d moves the weight rollers 41d further away from the drive-pulley shaft 44. As a result, the movable half 41b moves further towards the fixed half 41a and the movable half 42b of the driven pulley 42 moves further away from the fixed half 42a. Consequently, the radius of contact of the drive belt 43 to the drive pulley 41 becomes even larger and the radius of contact of the drive belt 43 to the driven pulley 42 becomes even smaller. This makes the transmission 40 have a reduction ratio smaller than one. In other words, the belt-type continuously variable transmission 40 becomes in the high-speed (overdrive) state. [0024] The starter clutch 50 includes the above-described clutch inner 51, a clutch outer 52 fixed on the driven-pulley shaft 45 at the left of the clutch inner 51. A centrifugal clutch portion 53 is also included in the starter clutch 50. With this centrifugal clutch portion 53, the clutch inner 51 can be connected to, or disconnected from, the clutch outer 52. Here, when the rotation speed of the driven-pulley shaft 45 reaches, or even exceeds, a certain predetermined speed, the clutch inner 51 and the clutch outer 52 are connected to each other by the starter clutch 50. Then, the driven pulley 42 rotates integrally with the driven-pulley shaft 45 so that the torque of the driven pulley 42 is transmitted to the driven-pulley shaft 45 via the starter clutch 50. In contrast, when the rotation speed of the driven-pulley shaft 45 comes down to, or falls below, the certain predetermined speed, the clutch inner 51 and the clutch outer 52 are disconnected from each other. Then, the driven pulley 42 becomes loose on the driven-pulley shaft 45 so that the transmission of the torque from the driven pulley 42 to the driven-pulley shaft 45 is interrupted (the belt-type continuously variable transmission 4 0 is in the neutral state). [0025] The output shaft 60 is supported by the bearings B8 and B9, attached, respectively, to the walls lla and lib of the crank case 11, and is capable of rotating freely. The left end portion of the output shaft 60 extends, penetrating the left-side wall lib of the crank case 11, out of the casing 10 (out of the crank case 11) . The output shaft 60 and the left end portion of the driven-pulley shaft 45 (the portion of the driven-pulley shaft 45 extending within the crank case 11) are linked by a speed reduction mechanism 61, which is made up of a plurality of gears. The torque of the engine 20 (the torque of the crankshaft 26) , transmitted to the driven-pulley shaft 45 via the starter clutch 50, is subjected to a speed reduction by the speed reduction mechanism 61, and then is taken out of the power unit 1 from the output shaft 60. Note that a drive sprocket of the unillustrated second speed reduction mechanism (a chain-sprocket type power-transmission mechanism transmitting the torque of the engine 20 to the rear wheel of the motorcycle, while reducing the speed thereof) is attached to a portion of the output shaft 60, which portion sticks out of the casing 10. [0026] A kick starter spindle 10 is supported at the rear end of the mission case 12 and is capable of rotating freely. The right end portion of the kick starter spindle 10 extends out of the mission case 12. To this portion, which sticks out of the mission case 12, a kick starter pedal (not illustrated) is attached. A return spring 11 is attached to the middle portion of the kick starter spindle 10, and, at the left of the return spring 11, a kick starter drive gear G3 is fixed to the kick starter spindle 10. The kick starter drive gear G3 meshes with a first idle gear for kick starter G4, which is attached to the output shaft 60 at its right end portion and idles on the output shaft 60. Furthermore, the first idle gear for kick starter G4 meshes with a second idle gear for kick starter G5, which is provided at a portion of the driven-pulley shaft 45 between the bearing B5 and the wall 12a of the mission case 12. This second idle gear for kick starter G5 is placed in a way that the second idle gear idles on the driven-pulley shaft 45. A third idle gear for kick starter G6, which is provided integrally with, and at the right of, the second idle gear for kick starter G5, meshes with the above-described drive-pulley-shaft drive gear Gl, which is provided at the right end portion of the crank shaft 26. [0027] When the engine 20 is not in operation, a stamp of the driver on the above-mentioned kick starter pedal makes the kick starter spindle 10 rotate. The torque of the kick starter spindle 70 is transmitted sequentially to the kick starter drive gear G3, the first idle gear for kick starter G4, the second idle gear for kick starter G5r the third idle gear for kick starter G6, and the drive-pulley-shaft drive gear Gl. This torque, thus transmitted, forces the crankshaft 26 to rotate, and the engine 20 can be made to start. [0028] A rotation shaft 81 of the alternator 80 is attached to the left end portion of the crank shaft 26 (the end portion which extends to the left, penetrating the left-side wall lib of the crank case 11) . The alternator 80, which is housed in a space between the alternator cover 14 and the left-side wall lib of the crank case 11, rotates along with the crankshaft 26. The alternator 80 generates electricity while the crankshaft 26 is rotating. [0029] As is shown in Figs. 2 and 3, the oil pump 90 is provided in a space between the right-side wall lla of the crank case 11 and the wall 12a of the mission case 12. This oil pump 90 is a trochoid pump, and is made up of an oil-pump rotation shaft 91, an inner rotor 92, an outer rotor 93, a housing 94 and an oil-pump driven gear G8. The oil-pump rotation shaft 91 is supported at its both ends by the right-side wall lla of the crank case 11 and by the wall 12a of the mission case 12. The inner rotor 92 is supported by the oil-pump rotation shaft 91, and the outer rotor 93 is provided at the outer circumference side of the inner rotor 92. The housing 94 is attached to the right-side wall lla of the crank case 11, and covers the outer part of the outer rotor 93. The oil-pump driven gear G8 is provided at the portion of the oil-pump rotation shaft 91, which portion extends out to the right, penetrating the housing 94. In this way, the oil-pump rotation shaft 91 is placed at a position offset from the drive-pulley shaft 44 (see Fig. 3). When the torque of the crankshaft 26 rotates the drive-pulley shaft 44, the above-described oil-pump drive gear Gl, attached to this drive-pulley shaft 44, also rotates, and then the oil-pump driven gear G8, meshing with this oil-pump drive gear G7, rotates integrally with the oil-pump rotation shaft 91. Accordingly, the inner rotor 92 and the outer rotor 93 rotate relatively to each other, and the rotation makes the oil pump 90 suck the oil in and force it out. With this operation of oil pump 90— sucking the oil in and forcing it out—the oil is sucked in through the oil intake port 101 (see Fig. 2) , the oil is then pressurized, and, eventually, the oil is forced out through the oil outlet port 102 (see Fig. 2) . The oil is then supplied to each of the portions of the engine 20. [0030] In this power unit 1, as is described above, the rotation shaft of the oil pump 90 (the oil-pump rotation shaft 91) is provided at the position offset from the drive-pulley shaft 44 which is a supporting shaft of the drive pulley 41. In addition, the oil pump 90 is driven by the oil-pump drive gear Gl provided on the drive-pulley shaft 44. The power unit 1 with this configuration is characterized in that the entire body of the power unit 1 has a smaller dimension in the width directions than a power unit with the oil pump 90 being provided at an end portion of the drive-pulley shaft 44. For this reason, this power unit 1 is suitable for being mounted on a motorcycle. Furthermore, in this power unit 1, the rotation speed of the oil pump 90 can be adjusted easily by the gear ratio between the oil-pump drive gear Gl and the oil-pump driven gear G8, which is provided on the oil-pump rotation shaft 91, and which meshes with the oil-pump drive gear Gl. Consequently, the oil pump 90 is prevented from rotating so rapidly that such an inconvenience as getting air bubbles trapped in the oil would take place. [0031] This power unit 1 can have another configuration in which the drive-pulley shaft 44 and the crankshaft 26 are formed as a single shaft (i.e. the drive pulley 41 is provided on the crankshaft 26) . Even such a configuration can have the above described advantageous effects. Since the drive pulley can be arranged closely to the crankshaft, the dimension of the entire body of the power unit 1 in the width directions, however, can be made smaller than otherwise with the following configuration as shown in this embodiment. In the configuration, the drive-pulley shaft 44—the supporting shaft of the drive pulley 41—and the crankshaft 26 are separate bodies, the two shafts 44 and 26 are placed in parallel to each other, and the drive-pulley shaft 44 is driven by the drive-pulley-shaft drive Gear Gl provided on the crankshaft 26. [0032] Additionally, in this power unit 1, the crankshaft 26 is placed between the drive-pulley shaft 44 and the driven-pulley shaft 45. Accordingly, the end portion of the crankshaft 26 is placed in a space between the drive-pulley shaft 44 and the driven-pulley shaft 4 5, which renders the dimension of the entire body of the power unit 1 in the front to rear directions smaller than otherwise. [0033] Furthermore, in this power unit 1, the starter clutch 50, which transmits the torque of the driven pulley 42 to the driven-pulley shaft 45, is provided on the driven-pulley shaft 45, and at a place between the driven pulley 42 and the wall lla of the crank case 11. Accordingly, the entire body of the power unit 1 with this configuration has a smaller dimension in the width directions than a power unit 1 with the clutch 50 being provided outside of the driven-pulley shaft 45 (at the side opposite the crankshaft 26) . A different configuration is also possible, in which the starter clutch 50 is provided on the driven-pulley shaft 45 and at the position outside of the driven pulley 42 (at the right of the driven pulley, that is, at the side thereof near the mission cover 13) . Nevertheless, such an arrangement as in this embodiment renders the dimension of the entire body of the power unit 1 in the width directions small, which in turn renders the power unit 2 more suitable for being mounted on a motorcycle than otherwise. Here, in the above-described embodiment, the oil-pump drive gear Gl, which drives the oil pump 90, is provided on the drive-pulley shaft 44. The oil-pump drive gear Gl, however, is not necessarily provided on the drive-pulley shaft 44, as long as be attached to any shaft other than the crankshaft 26. Suppose a case where the starter clutch is provided on the driven-pulley shaft 45, and at the position between the driven pulley 42 and the wall lla of the crank case 22. In this case, the dimension of the entire body of the power unit 2 in the width directions can be made small, but such an arrangement of the starter clutch 50 may eliminate a space where the oil-pump drive gear Gl is provided on the crankshaft 26. Even in such a case, provision of the oil-pump drive gear Gl on any shaft other than the crankshaft 26 makes it possible to drive the oil pump. [0034] Explanations have been given thus far of a preferred embodiment of the present invention, but the scope of the present invention is not limited to the embodiment described above. For example, in the explanations of the above-described embodiment, the oil pump 90 is a trochoid pump, but other types of oil pump (for example, the internal gear type, the external gear type and the vane type) may be used as the oil pump 90, as long as the pump is operated by the torque of the engine 20 to supply oil to each of the portions of the engine 20. Furthermore, in the above-described embodiment, the present invention is employed in a motorcycle, but it is only an example. The present invention can be employed in other power machinery such as an automobile. [Brief Description of the Drawings] [0035] [Fig. 1] Fig. 1 is a cross-sectional view of a power unit in an embodiment of the present invention. [Fig. 2] Fig. 2 is a local sectional view of the above-mentioned power unit taken along the line II-II in Fig. 1. [Fig. 3] Fig. 3 is a local sectional view of the above-mentioned power unit taken along the line III-III in Fig. 1. [Explanation of the Reference Numerals] [0036] 2 POWER UNIT 11 CRANK CASE 11A RIGHT-SIDE WALL OF THE CRANK CASE (WALL OF THE CRANK CASE) 12 MISSION CASE 20 ENGINE 26 CRANKSHAFT 40 BELT-TYPE CONTINUOUSLY VARIABLE TRANSMISSION 41 DRIVE PULLEY 42 DRIVEN PULLEY 43 DRIVE BELT 44 DRIVE-PULLEY SHAFT 45 DRIVEN-PULLEY SHAFT 50 STARTER CLUTCH (CLUTCH MECHANISM) 90 OIL PUMP 91 OIL-PUMP ROTATION SHAFT (ROTATION SHAFT OF OIL PUMP) Gl DRIVE-PULLEY-SHAFT DRIVE GEAR G2 DRIVE-PULLEY-SHAFT DRIVEN GEAR Gl OIL-PUMP DRIVE GEAR [Document Name] Scope of Claims [Claim 1] A power unit comprising: an engine; and a belt-type continuously variable transmission, which is placed as being separated from the engine by a wall of a crank case, housing a crankshaft of the engine, and which changes the torque of the crankshaft sticking out of the wall of the crank case, the power unit wherein the belt-type continuously variable transmission has: a drive pulley to which the torque of the crankshaft is inputted; a driven pulley which is provided in parallel to the drive pulley; and a drive belt which is looped between the drive pulley and the driven pulley, and which transmits the torque of the drive pulley to the driven pulley; a rotation shaft of an oil pump supplying oil to each portion of the engine is provided at a position offset from a supporting shaft of the drive pulley; and the oil pump is driven by an oil-pump drive gear provided on the supporting shaft of the drive pulley. [Claim 2] The power unit as recited in claim 1, wherein the supporting shaft of the drive pulley and the crankshaft are separate bodies, and are placed in parallel to each other, and the supporting shaft of the drive pulley is driven by a drive-pulley-supporting-shaft drive gear that is provided on the crankshaft. [Claim 3] The power unit as recited in any one of claim 1 and 2, wherein the crankshaft is placed between the supporting shaft of the drive pulley and the supporting shaft of the driven pulley. [Claim 4] A power unit comprising: an engine; and a belt-type continuously variable transmission, which is placed as being separated from the engine by a wall of a crank case, housing a crankshaft of the engine, and which changes the torque of the crankshaft sticking out of the wall of the crank case, the power unit wherein the belt-type continuously variable transmission has: a drive pulley to which the torque of the crankshaft is inputted; a driven pulley which is provided in parallel to the drive pulley; and a drive belt which is looped between the drive pulley and the driven pulley, and which transmits the torque of the drive pulley to the driven pulley; a clutch mechanism for transmitting the torque of the driven pulley to the supporting shaft of the driven pulley is provided on the supporting shaft of the driven pulley and at a position between the driven pulley and the wall of the crank case; and an oil pump for supplying oil to each portion of the engine is driven by an oil-pump drive gear attached on a shaft different from the crankshaft.

Documents:

2400-che-2006 complete specification as granted.pdf

2400-che-2006 abstract.pdf

2400-che-2006 claims.pdf

2400-che-2006 correspondence others.pdf

2400-che-2006 form-3.pdf

2400-che-2006 petition.pdf

2400-che-2006-abstract.pdf

2400-che-2006-abstractimage.jpg

2400-che-2006-claims.pdf

2400-che-2006-correspondnece-others.pdf

2400-che-2006-description(complete).pdf

2400-che-2006-drawings.pdf

2400-che-2006-form 1.pdf

2400-che-2006-form 18.pdf

2400-che-2006-form 26.pdf

2400-che-2006-form 3.pdf

2400-che-2006-form 5.pdf

2400-che-2006-priority document.pdf

EXAMINATION REPORT REPLY.PDF