Patent ID: 12187379

DESCRIPTION OF EMBODIMENTS

In a power unit according to an exemplary embodiment of the present invention, a gear case is provided on one side of the motor case in a vehicle width direction, and an opening of the gear case is covered with a gear case cover from the outside in the vehicle width direction. A motor shaft protrudes toward the gear case from the motor case, a drive shaft protrudes outward from the gear case cover in the vehicle width direction, and a power transmission mechanism is configured to transmit power from the motor shaft to the drive shaft. An output gear is fixed to the motor shaft inside the gear case cover, a drive sprocket is fixed to the drive shaft outside the gear case cover, and the output gear and the drive sprocket are provided on one side in the vehicle width direction. Accordingly, the power transmission mechanism is formed compactly. The drive sprocket outside the gear case cover is positioned inward, in the vehicle width direction, of the output gear inside the gear case cover, and the drive sprocket is prevented from protruding outward in the vehicle width direction. The chain line of the drive chain wound around the drive sprocket of the power unit and the driven sprocket of the drive wheel is moved inward in the vehicle width direction, and the sizes of the electric vehicle and the power unit are reduced.

Embodiment

Hereinafter, an electric vehicle according to the present embodiment will be described with reference to the accompanying drawings.FIG.1is a side view of a vehicle body frame and a vehicle rear portion according to the present embodiment. In the following drawings, an arrow FR indicates a vehicle front side, an arrow RE indicates a vehicle rear side, an arrow L indicates a vehicle left side, and an arrow R indicates a vehicle right side.

As shown inFIG.1, various components such as a power unit30and an electrical system are mounted on a vehicle body frame10of the electric vehicle. A main frame12extends rearward and obliquely downward from a head pipe11of the vehicle body frame10. A rear portion of the main frame12is a body frame13bent downward. A down frame14extends downward from the head pipe11. A lower frame15bent rearward is connected to a lower portion of the down frame14. As described above, the vehicle body frame10is formed in a cradle shape. The power unit30is attached to the inside of the vehicle body frame10, via a bracket (not shown) or the like.

A swing arm17is swingably supported at an intermediate portion of the body frame13. The swing arm17extends rearward from the body frame13. A rear wheel19is rotatably supported at a rear end of the swing arm17. A front side of the swing arm17and a lower portion of the rear cushion21are connected via a triangular cushion lever22. The cushion lever22and the body frame13are connected via a cushion rod23. The rear cushion21is configured to expand and contract according to the swinging of the swing arm17. Thus, the unevenness of a road surface is absorbed, the vibration is prevented, and the ground contact performance between the road surface and the rear wheel19is improved.

A drive sprocket67is fixed to a drive shaft65of the power unit30. A driven sprocket24is fixed to an axle18of the rear wheel19. A drive chain25is wound around the drive sprocket67and the driven sprocket24. Power of an electric motor61(seeFIG.5) of the power unit30is transmitted to the rear wheel19, via the drive chain25. In such an electric vehicle, the vehicle size increases due to the protrusion, of the drive chain line, toward the outside in a vehicle width direction. Therefore, in the power unit30according to the present embodiment, the drive sprocket67is moved inward in the vehicle width direction, and the protrusion of the drive chain line is reduced.

A power unit will be described with reference toFIGS.2to5.FIG.2is a perspective view of the power unit according to the present embodiment.FIG.3is a top view of the power unit according to the present embodiment.FIG.4is a perspective view of the power unit from which a gear case cover is removed, according to the present embodiment.FIG.5is a perspective view of a power transmission mechanism and an electric motor according to the present embodiment.

As shown inFIGS.2and3, a unit case of the power unit30is divided into five parts of a gear case cover51, a gear case41, a left motor case39, a right motor case32, and a motor case cover31, from a left side to a right side. An electric motor61(seeFIG.5) is provided inside the gear case41, the left motor case39, and the right motor case32. A power transmission mechanism70(seeFIG.4) including a plurality of gears and the like is provided inside the gear case cover51and the gear case41. In this way, the gear case41is used not only as a case for the gears but also as a case for the electric motor61.

The right motor case32covers a right opening of the left motor case39. An OUT pipe34for cooling water is provided on a front side of an upper surface of the right motor case32. An IN pipe35for cooling water is provided on a rear side of a lower surface of the right motor case32. A box-shaped housing36bulges rightward from an outer surface of the right motor case32. A resolver37for detecting a rotor angle of the electric motor61is provided on an upper surface of the housing36. A rear side of the upper surface of the housing36protrudes rearward and obliquely upward. A connector38for a three-phase line is provided at a protruding portion of the housing36.

The gear case41is formed with a cylindrical cover42that covers a left opening of the left motor case39and that accommodates a left end side of the electric motor61. A case protrudes rearward from the cylindrical cover42, and a peripheral wall44surrounds a protruding portion43and a center of the cylindrical cover42(seeFIG.6in particular). The gear case cover51is attached to the peripheral wall44of the gear case41, and a space for providing the power transmission mechanism70is formed. As described above, in the power unit30according to the present embodiment, the gear case41is provided on a left side (one side in the vehicle width direction) of the left motor case39, and an opening of the peripheral wall44of the gear case41is covered with the gear case cover51from the outside in the vehicle width direction.

A region of a side surface of the gear case cover51from a rear side to a center lower portion is one step lower inward in the vehicle width direction than a region of the side surface of the gear case cover51from a front side to a center upper portion. A lower step portion53of the gear case cover51is flat, and the drive sprocket67is provided on a flat surface. The drive sprocket67is positioned inward, in the vehicle width direction, of an upper step portion52of the gear case cover51. As viewed from above, a mating surface45of the gear case41and the gear case cover51is inclined inward in the vehicle width direction toward rear of the power unit. Thus, the drive sprocket67is easily provided inward in the vehicle width direction.

As shown inFIGS.4and5, a motor shaft62of the electric motor61penetrate through the center of the cylindrical cover42of the gear case41, and protrudes from a left motor case39side toward the gear case41. An output gear63is fixed to a distal end of the motor shaft62. The drive shaft65is provided in the protruding portion43of the gear case41behind the motor shaft62. The drive shaft65protrudes outward in the vehicle width direction from the gear case cover51(seeFIG.2). A drive gear66is provided in an inner side, in the vehicle width direction, of the drive shaft65. The drive sprocket67is fixed to a distal end of the drive shaft65on an outer side in the vehicle width direction.

The output gear63is fixed to the motor shaft62, inside the gear case cover51. The drive sprocket67is fixed to the drive shaft65, outside the gear case cover51. More specifically, the output gear63is accommodated inside the upper step portion52(seeFIG.2) of the gear case cover51. The drive sprocket67is exposed to the outside of the lower step portion53(seeFIG.2) of the gear case cover51. The drive sprocket67is positioned inward, in the vehicle width direction, of the output gear63such that the chain line of the drive chain25(seeFIG.1) does not protrude outward in the vehicle width direction, and the output gear63and the drive sprocket67are misaligned in the vehicle width direction.

The power transmission mechanism70configured to transmit power from the motor shaft62to the drive shaft65is accommodated inside the gear case41and the gear case cover51. The power transmission mechanism70includes first to third intermediate shafts71to73arranged from the motor shaft62toward the drive shaft65. The first intermediate shaft71is provided with first and second intermediate gears74,75. The second intermediate shaft72is provided with third and fourth intermediate gears76,77. The third intermediate shaft73is provided with a fifth intermediate gear78. The motor shaft62, the drive shaft65, and the first to third intermediate shafts71to73are supported, via bearings69, on the gear case41and the gear case cover51.

The first intermediate gear74meshes with the output gear63of the motor shaft62, and power is transmitted from the output gear63to the first intermediate gear74. The second intermediate gear75is located inside, in the vehicle width direction, the first intermediate gear74. The first intermediate gear74and the second intermediate gear75are integrally rotated via the first intermediate shaft71. The third intermediate gear76meshes with the second intermediate gear75, and power is transmitted from the second intermediate gear75to the third intermediate gear76. The fourth intermediate gear77is located inside, in the vehicle width direction, the third intermediate gear76. The third intermediate gear76and the fourth intermediate gear77are integrally rotated via the second intermediate shaft72.

The fifth intermediate gear78meshes with the fourth intermediate gear77, and power is transmitted from the fourth intermediate gear77to the fifth intermediate gear78. The drive gear66meshes with the fifth intermediate gear78, and power is transmitted from the fifth intermediate gear78to the drive gear66. The drive sprocket67is located outside, in the vehicle width direction, the drive gear66. The drive gear66and the drive sprocket67are integrally rotated via the drive shaft65. Power is transmitted from the electric motor61to the drive sprocket67, via a gear train including the output gear63, the first intermediate gear74to the fifth intermediate gear78, and the drive gear66.

The component layout of the power unit will be described in detail with reference toFIGS.6to8.FIG.6is a right side view of the power unit from which the gear case cover is removed, according to the present embodiment.FIG.7is a bottom view of the power unit from which the gear case cover is removed, according to the present embodiment.FIG.8is a rear view of the power unit from which the gear case cover is removed, according to the present embodiment.

As shown inFIG.6, as viewed from a side, the motor shaft62and the drive shaft65are positioned at the same height. The first intermediate shaft71to the third intermediate shaft73of the power transmission mechanism70are positioned above the motor shaft62and the drive shaft65. The first intermediate shaft71is located rearward and obliquely above the motor shaft62. The second intermediate shaft72is located rearward and obliquely above the first intermediate shaft71. The third intermediate shaft73is located rearward and obliquely below the second intermediate shaft72. The drive shaft65is located below the third intermediate shaft73. The space for providing the power transmission mechanism70is provided above the motor shaft62and the drive shaft65, and the longitudinal length of the power transmission mechanism70is reduced. Thus, the size of the power unit30is reduced.

The cylindrical cover42bulges from an outer surface of the gear case41. The motor shaft62and the first intermediate shaft71are located on the cylindrical cover42, as viewed from the side. The first intermediate shaft71is provided with the first intermediate gear74that is the most upstream gear, in a power transmission direction, among the plurality of intermediate gears. The first intermediate gear74has the largest diameter. Most of the first intermediate gear74overlaps the cylindrical cover42, as viewed from the side. The first intermediate gear74is provided on a side of the cylindrical cover42. Accordingly, the third intermediate gear76to the fifth intermediate gear78are provided at a position one step lower, in the vehicle width direction, than the cylindrical cover42. Thus, the drive sprocket67is easily provided on an inner side in the vehicle width direction.

The protruding portion43extends rearward from the cylindrical cover42of the gear case41. The second intermediate shaft72, the third intermediate shaft73, and the drive shaft65are provided along an outer periphery of the cylindrical cover42in the protruding portion43. The third intermediate gear76to the fifth intermediate gear78, the drive gear66(seeFIG.7), and the drive sprocket67(seeFIG.7) are compactly provided around the cylindrical cover42, and the size of the power unit30is reduced. In the present embodiment, not only the motor shaft62and the drive shaft65but also the first intermediate shaft71and the third intermediate shaft73have the same height. However, the two shafts do not need to have completely the same height, and may have an error to the extent that the two shafts can be regarded as having substantially the same height.

The power transmission mechanism70further includes the fifth intermediate gear78to provide the drive shaft65directly behind the motor shaft62. In order to increase the total speed reduction ratio of the power transmission mechanism70, it is desirable to increase the number of teeth of the drive gear66more than that of the fifth intermediate gear78. However, in that case, the outer diameter of the drive gear66is increased, and the drive shaft65is moved away from the motor shaft62. Therefore, in the present embodiment, by reducing the number of teeth of the drive gear66less than that of the fifth intermediate gear78, the outer diameter of the drive gear66is reduced, the drive shaft65is brought close to the motor shaft62, and the size of the power unit30is reduced.

As shown inFIGS.7and8, as viewed from above, the mating surface45of the gear case41and the gear case cover51is inclined inward in the vehicle width direction toward rear of the power unit30. The output gear63, the first intermediate gear74to the third intermediate gear76, and the drive sprocket67are provided outside, in the vehicle width direction, of the mating surface45. The fourth intermediate gear77, the fifth intermediate gear78(seeFIG.5), and the drive gear66are provided inside, in the vehicle width direction, of the mating surface45. The output gear63and the first intermediate gear74to the third intermediate gear76that protrude from the mating surface45are accommodated in the upper step portion52of the gear case cover51. The drive sprocket67protruding from the mating surface45is exposed from the lower step portion53of the gear case cover51.

The mating surface45is inclined inward in the vehicle width direction toward rear of the power unit30, and a rear portion of the gear case cover51is formed one step lower than a front portion of the gear case cover51. Accordingly, the rear portion of the gear case cover51is moved inward in the vehicle width direction, and the drive sprocket67outside the gear case cover51is provided on the inner side in the vehicle width direction. The drive sprocket67is positioned inward, in the vehicle width direction, of the output gear63. The chain line of the drive chain25(seeFIG.1) hooked on the drive sprocket67is moved inward, in the vehicle width direction, of an upper end portion of the gear case cover51, and the size of the power unit30is reduced.

Inside the gear case cover51, the output gear63is provided on the outermost side in the vehicle width direction, and the first intermediate gear74to the fifth intermediate gear78and the drive gear66are provided on the inner side in the vehicle width direction toward downstream in the power transmission direction. The first intermediate gear74is provided at the same position as the output gear63in the vehicle width direction. The second intermediate gear75and the third intermediate gear76are provided inside, in the vehicle width direction, of the first intermediate gear74. The fourth intermediate gear77, the fifth intermediate gear78, and the drive gear66are provided inside, in the vehicle width direction, of the third intermediate gear76. Accordingly, the drive sprocket67coaxial with the drive gear66is easily provided on the inner side in the vehicle width direction.

In a state in which the gear case cover51is removed, as viewed from the rear, most of the gears are visible. As viewed from the rear, the first intermediate gear74to the third intermediate gear76are provided outside an outer surface of the cylindrical cover42, and the fourth intermediate gear77, the fifth intermediate gear78, and the drive gear66are provided inside, in the vehicle width direction, of the outer surface of the cylindrical cover42. The fourth intermediate gear77, the fifth intermediate gear78, and the drive gear66overlap the cylindrical cover42. Accordingly, the drive sprocket67coaxial with the drive gear66is easily provided on the inner side in the vehicle width direction. The lateral width of the power transmission mechanism70is reduced, and the size of the power unit30is reduced.

As described above, according to the power unit30in the present embodiment, the output gear63and the drive sprocket67are provided on one side in the vehicle width direction. Thus, the power transmission mechanism70is formed compactly. The drive sprocket67outside the gear case cover51is positioned inward, in the vehicle width direction, of the output gear63inside the gear case cover51. Thus, the drive sprocket67is prevented from protruding outward in the vehicle width direction. The chain line of the drive chain25wound around the drive sprocket67of the power unit30and the driven sprocket24of the rear wheel19is moved inward in the vehicle width direction, and the sizes of the electric vehicle and the power unit30are reduced.

In the present embodiment, the power transmission mechanism includes a gear train. However, it is sufficient that the power transmission mechanism is configured to transmit power from the motor shaft to the drive shaft.

In the present embodiment, as viewed from above, the mating surface of the gear case and the gear case cover is inclined inward in the vehicle width direction toward rear of the power unit. Alternatively, the mating surface may not be inclined as long as the drive sprocket can be provided inside the output gear in the vehicle width direction.

In the present embodiment, the power transmission mechanism includes three intermediate shafts and five intermediate gears. However, the number, the installation locations, the sizes, and the like of the intermediate shafts and the intermediate gears of the power transmission mechanism are not particularly limited.

In the present embodiment, the number of teeth of the drive gear is smaller than that of the fifth intermediate gear. Alternatively, the number of teeth of the drive gear may be larger than that of the fifth intermediate gear as long as the drive shaft can be provided behind the motor shaft.

The power unit according to the present embodiment is not limited to the above straddle-type electric vehicle, and may be applied to other straddle-type electric vehicles. The straddle-type electric vehicle is not limited to an electric vehicle in which a driver rides on a seat in a posture of straddling the seat, and includes a scooter-type electric vehicle in which the driver rides on the seat without straddling the seat.

As described above, a first aspect provides a power unit (30) in which a gear case (41) is provided on one side, in a vehicle width direction, of a motor case (the left motor case39and the right motor case32), an opening of the gear case being covered with a gear case cover (51) from an outside in the vehicle width direction. The power unit (30) includes: a motor shaft (62) protruding toward the gear case from a motor case side; a drive shaft (65) protruding outward in the vehicle width direction from the gear case cover; and a power transmission mechanism (70) configured to transmit power, to the drive shaft, from the motor shaft. An output gear (63) is fixed to the motor shaft, inside the gear case cover. A drive sprocket (67) is fixed to the drive shaft, outside the gear case cover. The drive sprocket is positioned inward, in the vehicle width direction, of the output gear. According to this configuration, the output gear and the drive sprocket are provided on one side in the vehicle width direction, and the power transmission mechanism is formed compactly. The drive sprocket outside the gear case cover is positioned inward, in the vehicle width direction, of the output gear inside the gear case cover, and the drive sprocket is prevented from protruding outward in the vehicle width direction. The chain line of the drive chain wound around the drive sprocket of the power unit and the driven sprocket of the drive wheel is moved inward in the vehicle width direction, and the sizes of the electric vehicle and the power unit are reduced.

A second aspect is directed to the first aspect, in which, as viewed from above, a mating surface (45) of the gear case and the gear case cover is inclined inward in the vehicle width direction toward rear of the power unit, and in which the drive sprocket is positioned behind the output gear. According to this configuration, the rear portion of the gear case cover is moved inward in the vehicle width direction, and the drive sprocket outside the gear case cover is provided on the inner side in the vehicle width direction.

A third aspect is directed to the first aspect and the second aspect, in which the power transmission mechanism includes a plurality of intermediate shafts (the first intermediate shaft71to the third intermediate shaft73) provided with a plurality of intermediate gears (the first intermediate gear74to the fifth intermediate gear78), and in which, inside the gear case cover, the output gear is provided on an outermost side in the vehicle width direction, and inside the gear case cover, the plurality of intermediate gears are provided such that an intermediate gear positioned on a downstream side in a power transmission direction is positioned on an inner side, in the vehicle width direction, of an intermediate gear positioned on an upstream side in a power transmission direction. According to this configuration, the drive sprocket is easily provided on the inner side in the vehicle width direction.

A fourth aspect is directed to the third aspect, in which a cylindrical cover (42) bulges from an outer surface of the gear case, the cylindrical cover covering an opening of the motor case, in which among the plurality of intermediate gears, an intermediate gear (the first intermediate gear74) positioned on a most upstream in the power transmission direction has the largest diameter, and in which as viewed from a side, the intermediate gear positioned on the most upstream in the power transmission direction overlaps the cylindrical cover. According to this configuration, the intermediate gear having a large diameter is provided on the side of the cylindrical cover. Accordingly, the intermediate gear behind the intermediate gear having a large diameter is provided at a position one step lower, in the vehicle width direction, than the cylindrical cover. Thus, the drive sprocket is easily provided on a further inner side in the vehicle width direction.

A fifth aspect is directed to the third aspect or the fourth aspect, in which a first intermediate shaft (the second intermediate shaft72and the third intermediate shaft73) and the drive shaft (65) are provided along an outer periphery of the cylindrical cover, the first intermediate shaft being positioned behind a second intermediate shaft to which the intermediate gear positioned on the most upstream in the power transmission direction is fixed. According to this configuration, a part of the intermediate gears and the drive sprocket are compactly provided around the cylindrical cover, and the size of the power unit is reduced.

A sixth aspect is directed to any one of the third aspect to the fifth aspect, in which as viewed from the side, the motor shaft and the drive shaft are positioned at the same height, and as viewed from the side, the plurality of intermediate shafts are positioned above the motor shaft and the drive shaft. According to this configuration, the longitudinal length of the power transmission mechanism is reduced, and the size of the power unit is reduced.

A seventh aspect is directed to any one of the third aspect to the sixth aspect, in which the drive shaft is provided with a drive gear (66), and in which, as viewed from rear, the drive gear and an intermediate gear (the fourth intermediate gear77and the fifth intermediate gear78), among the plurality of intermediate gears, positioned on the downstream side in the power transmission direction overlap the cylindrical cover. According to this configuration, the drive sprocket coaxial with the drive gear is easily provided on the inner side in the vehicle width direction. The lateral width of the power transmission mechanism is reduced, and the size of the power unit is reduced.

An eighth aspect is directed to any one of the third aspect to the seventh aspect, in which the number of teeth of the drive gear is smaller than that the number of teeth of an intermediate gear (the fifth intermediate gear78) positioned on a most downstream in the power transmission direction. According to this configuration, even in a case where the intermediate gear is added in order to provide the drive shaft rearward, the drive shaft is brought close to the motor shaft by an amount corresponding to the reduction in the diameter of the drive gear, and the size of the power unit is reduced.

Although the present embodiment has been described, other embodiments may be used in which the above embodiment and modification are combined entirely or partially.

The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.