Power unit

Abstract

To reduce the body size of an electric vehicle and the unit size of a power unit.SOLUTION: In a power unit (30), a gear case (41) is provided at one side of motor cases (32, 39) in a vehicle width direction, and an opening of the gear case is covered with a gear case cover (51) from the outer side of the vehicle width direction. The power unit is provided with a motor shaft protruding to the gear case side from the motor case sides, a drive shaft protruding to the outside of the vehicle width direction from the gear case cover, and a power transmission mechanism (70) for transmitting power from the motor shaft to the drive shaft. An output gear (63) is fixed to the motor shaft on the inside of the gear case cover, and a drive sprocket (67) is fixed to the drive shaft on the outside of the gear case cover. The drive sprocket is located on the inner side of the vehicle width direction with respect to the output gear.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a power unit for an electric vehicle.

Background Art

[0002] Conventionally, as a power unit for an electric vehicle, one that decelerates the power from an electric motor and transmits it to the rear wheels is known (for example, see Patent Document 1). A reduction gear train is accommodated in the gear case of the power unit described in Patent Document 1, and power is transmitted from the motor shaft of the electric motor to the drive shaft via the reduction gear train. The drive shaft of the power unit protrudes laterally from the gear case cover, and a drive sprocket is attached to the tip of the drive shaft. A driven sprocket is attached to the axle of the rear wheel, and power is transmitted from the drive sprocket to the driven sprocket via a drive chain.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the electric vehicle described in Patent Document 1, since the chain line of the drive chain protrudes outward in the vehicle width direction, there is a problem that the electric vehicle and the power unit become larger in size.

[0005] The present invention has been made in view of this point, and an object thereof is to provide a power unit capable of reducing the vehicle size and the unit size.

Means for Solving the Problems

[0006] A power unit according to one aspect of the present invention is a power unit in which a gear case is provided on one side in the vehicle width direction of a motor case, and the opening of the gear case is covered by a gear case cover from the outside in the vehicle width direction, and comprises a motor shaft protruding from the motor case side to the gear case side, a drive shaft protruding outward from the gear case cover in the vehicle width direction, and a power transmission mechanism that transmits power from the motor shaft to the drive shaft, wherein an output gear is fixed to the motor shaft inside the gear case cover, and a drive sprocket is fixed to the drive shaft outside the gear case cover, and the drive sprocket is positioned further inward in the vehicle width direction than the output gear, thereby solving the above problem. [Effects of the Invention]

[0007] According to one embodiment of the present invention, the power transmission mechanism is made compact by providing the output gear and drive sprocket on one side in the vehicle width direction. Furthermore, the drive sprocket, which is outside the gear case cover, is positioned further inward in the vehicle width direction than the output gear, which is inside the gear case cover, thereby suppressing the outward protrusion of the drive sprocket in the vehicle width direction. The chain line of the drive chain, which is wrapped around the drive sprocket of the power unit and the driven sprocket of the drive wheel, is moved inward in the vehicle width direction, resulting in a smaller electric vehicle and power unit. [Brief explanation of the drawing]

[0008] [Figure 1] This is a side view of the vehicle body frame and the rear of the vehicle in this embodiment. [Figure 2] This is a perspective view of the power unit in this embodiment. [Figure 3] This is a top view of the power unit in this embodiment. [Figure 4] This is a perspective view of the power unit with the gear case cover removed in this embodiment. [Figure 5] This is a perspective view of the power transmission mechanism and electric motor of this embodiment. [Figure 6]This is a right side view of the power unit with the gear case cover removed in this embodiment. [Figure 7] This is a bottom view of the power unit with the gear case cover removed in this embodiment. [Figure 8] This is a rear view of the power unit with the gear case cover removed in this embodiment. [Modes for carrying out the invention]

[0009] In one embodiment of the present invention, a gear case is provided on one side of the motor case in the vehicle width direction, and the opening of the gear case is covered by a gear case cover from the outside in the vehicle width direction. The motor shaft protrudes from the motor case towards the gear case, and the drive shaft protrudes from the gear case cover outward in the vehicle width direction, and power is transmitted from the motor shaft to the drive shaft by a power transmission mechanism. An output gear is fixed to the motor shaft inside the gear case cover, and a drive sprocket is fixed to the drive shaft outside the gear case cover, and the power transmission mechanism is made compact by providing the output gear and drive sprocket on one side in the vehicle width direction. In addition, the drive sprocket outside the gear case cover is positioned further inward in the vehicle width direction than the output gear inside the gear case cover, so that the outward protrusion of the drive sprocket in the vehicle width direction is suppressed. The chain line of the drive chain wrapped around the drive sprocket of the power unit and the driven sprocket of the drive wheel is moved inward in the vehicle width direction, resulting in a smaller electric vehicle and power unit. [Examples]

[0010] The electric vehicle of this embodiment will be described below with reference to the attached drawings. Figure 1 is a side view of the vehicle frame and rear of the vehicle of this embodiment. In the following figures, arrow FR indicates the front of the vehicle, arrow RE indicates the rear of the vehicle, arrow L indicates the left side of the vehicle, and arrow R indicates the right side of the vehicle.

[0011] As shown in Figure 1, the vehicle body frame 10 of the electric vehicle is equipped with various components such as the power unit 30 and electrical systems. The main frame 12 extends diagonally downward and rearward from the head pipe 11 of the vehicle body frame 10, and the rear of the main frame 12 is a body frame 13 that is bent downward. In addition, a down frame 14 extends downward from the head pipe 11, and a lower frame 15 that is bent rearward is connected to the lower part of the down frame 14. In this way, the vehicle body frame 10 is formed in a cradle shape, and the power unit 30 is attached to the inside of the vehicle body frame 10 via brackets (not shown), etc.

[0012] A swingarm 17 is pivotably supported in the middle of the body frame 13. The swingarm 17 extends rearward from the body frame 13, and a rear wheel 19 is rotatably supported at the rear end of the swingarm 17. The front of the swingarm 17 and the lower part of the rear cushion 21 are connected via a triangular cushion lever 22. The cushion lever 22 and the body frame 13 are also connected via a cushion rod 23. As the swingarm 17 pivots, the rear cushion 21 expands and contracts, absorbing road surface irregularities and suppressing vibrations, while also improving the contact between the road surface and the rear wheel 19.

[0013] A drive sprocket 67 is fixed to the drive shaft 65 of the power unit 30, and a driven sprocket 24 is fixed to the axle 18 of the rear wheel 19. A drive chain 25 is wrapped around the drive sprocket 67 and the driven sprocket 24, and the power of the electric motor 61 of the power unit 30 (see Figure 5) is transmitted to the rear wheel 19 via the drive chain 25. In such an electric vehicle, the vehicle size increases due to the outward protrusion of the drive chain line in the vehicle width direction. Therefore, in the power unit 30 of this embodiment, the drive sprocket 67 is moved inward in the vehicle width direction, thereby suppressing the protrusion of the drive chain line.

[0014] The power unit will be described with reference to FIGS. 2 to 5. FIG. 2 is a perspective view of the power unit of this embodiment. FIG. 3 is a top view of the power unit of this embodiment. FIG. 4 is a perspective view of the power unit with the gear case cover removed in this embodiment. FIG. 5 is a perspective view of the power transmission mechanism and the electric motor of this embodiment.

[0015] As shown in FIGS. 2 and 3, the unit case of the power unit 30 is divided into five parts: a gear case cover 51, a gear case 41, a left motor case 39, a right motor case 32, and a motor case cover 31 from left to right. An electric motor 61 (see FIG. 5) is installed inside the gear case 41, the left motor case 39, and the right motor case 32, and a power transmission mechanism 70 (see FIG. 4) composed of a plurality of gears and the like is installed inside the gear case cover 51 and the gear case 41. Thus, the gear case 41 is used not only as a case for gears but also as a case for the electric motor 61.

[0016] The right motor case 32 covers the opening on the right side of the left motor case 39. An OUT pipe 34 for cooling water is provided on the front side of the upper surface of the right motor case 32, and an IN pipe 35 for cooling water is provided on the rear side of the lower surface of the right motor case 32. A box-shaped housing 36 bulges out to the right from the outer surface of the right motor case 32, and a resolver 37 for detecting the rotor angle of the electric motor 61 is provided on the upper surface of the housing 36. The rear side of the upper surface of the housing 36 protrudes obliquely upward to the rear, and a connector 38 for three-phase lines is provided on the protruding portion of the housing 36.

[0017] The gear case 41 is formed with a cylindrical cover 42 that covers the opening on the left side of the left motor case 39 and houses the left end side of the electric motor 61. A case projects rearward from the cylindrical cover 42, and a peripheral wall 44 is formed so as to surround the projecting portion 43 and the center of the cylindrical cover 42 (see particularly FIG. 6). A gear case cover 51 is attached to the peripheral wall 44 of the gear case 41, thereby forming an installation space for the power transmission mechanism 70. Thus, in the power unit 30 of the present embodiment, the gear case 41 is provided on the left side (one side in the vehicle width direction) of the left motor case 39, and the opening of the peripheral wall 44 of the gear case 41 is covered from the outside in the vehicle width direction by the gear case cover 51.

[0018] The region from the rear side to the lower center of the side surface of the gear case cover 51 is one step lower in the vehicle width direction than the region from the front side to the upper center of the side surface of the gear case cover 51. The lower stage portion 53 of the gear case cover 51 is flat, and a drive sprocket 67 is installed on the flat surface. The drive sprocket 67 is positioned more inward in the vehicle width direction than the upper stage portion 52 of the gear case cover 51. In a top view, the mating surface 45 of the gear case 41 and the gear case cover 51 is inclined inward in the vehicle width direction toward the rear, facilitating the installation of the drive sprocket 67 inward in the vehicle width direction.

[0019] As shown in FIGS. 4 and 5, the motor shaft 62 of the electric motor 61 projects from the left motor case 39 side to the gear case 41 side through the center of the cylindrical cover 42 of the gear case 41. An output gear 63 is fixed to the tip of the motor shaft 62. A drive shaft 65 is installed in the projecting portion 43 of the gear case 41 behind the motor shaft 62, and the drive shaft 65 projects outward in the vehicle width direction from the gear case cover 51 (see FIG. 2). A drive gear 66 is provided on the inner side in the vehicle width direction of the drive shaft 65, and a drive sprocket 67 is fixed to the tip on the outer side in the vehicle width direction of the drive shaft 65.

[0020] The output gear 63 is fixed to the motor shaft 62 inside the gear case cover 51, and the drive sprocket 67 is fixed to the drive shaft 65 outside the gear case cover 51. More specifically, the output gear 63 is housed inside the upper section 52 (see Figure 2) of the gear case cover 51, and the drive sprocket 67 is exposed outside the lower section 53 (see Figure 2) of the gear case cover 51. To prevent the chain line of the drive chain 25 (see Figure 1) from protruding outward in the vehicle width direction, the drive sprocket 67 is positioned further inward in the vehicle width direction than the output gear 63, resulting in a misalignment between the output gear 63 and the drive sprocket 67 in the vehicle width direction.

[0021] A power transmission mechanism 70, which transmits power from the motor shaft 62 to the drive shaft 65, is housed inside the gear case 41 and the gear case cover 51. The power transmission mechanism 70 is provided with first to third intermediate shafts 71-73 arranged in line from the motor shaft 62 toward the drive shaft 65. The first intermediate shaft 71 is provided with first and second intermediate gears 74 and 75, the second intermediate shaft 72 is provided with third and fourth intermediate gears 76 and 77, and the third intermediate shaft 73 is provided with a fifth intermediate gear 78. The motor shaft 62, the drive shaft 65, and the first to third intermediate shafts 71-73 are supported by the gear case 41 and the gear case cover 51 via bearings 69.

[0022] The output gear 63 of the motor shaft 62 is meshed with the first intermediate gear 74, and power is transmitted from the output gear 63 to the first intermediate gear 74. The second intermediate gear 75 is located on the inside of the first intermediate gear 74 in the vehicle width direction, and the first intermediate gear 74 and the second intermediate gear 75 rotate together via the first intermediate shaft 71. The third intermediate gear 76 is meshed with the second intermediate gear 75, and power is transmitted from the second intermediate gear 75 to the third intermediate gear 76. The fourth intermediate gear 77 is located on the inside of the third intermediate gear 76 in the vehicle width direction, and the third intermediate gear 76 and the fourth intermediate gear 77 rotate together via the second intermediate shaft 72.

[0023] The fourth intermediate gear 77 is meshed with the fifth intermediate gear 78, and power is transmitted from the fourth intermediate gear 77 to the fifth intermediate gear 78. The fifth intermediate gear 78 is meshed with the drive gear 66, and power is transmitted from the fifth intermediate gear 78 to the drive gear 66. A drive sprocket 67 is located on the outer side of the drive gear 66 in the vehicle width direction, and the drive gear 66 and drive sprocket 67 rotate together via the drive shaft 65. Power is transmitted from the electric motor 61 to the drive sprocket 67 via a gear train consisting of the output gear 63, the first to fifth intermediate gears 74-78, and the drive gear 66.

[0024] The component layout of the power unit will be described in detail with reference to Figures 6 to 8. Figure 6 is a right side view of the power unit with the gear case cover removed in this embodiment. Figure 7 is a bottom view of the power unit with the gear case cover removed in this embodiment. Figure 8 is a rear view of the power unit with the gear case cover removed in this embodiment.

[0025] As shown in Figure 6, in a side view, the motor shaft 62 and the drive shaft 65 are positioned at the same height, and the first to third intermediate shafts 71-73 of the power transmission mechanism 70 are positioned above the motor shaft 62 and the drive shaft 65. The first intermediate shaft 71 is positioned diagonally above and behind the motor shaft 62, and the second intermediate shaft 72 is positioned diagonally above and behind the first intermediate shaft 71. The third intermediate shaft 73 is positioned diagonally below and behind the second intermediate shaft 72, and the drive shaft 65 is positioned below the third intermediate shaft 73. By securing installation space for the power transmission mechanism 70 above the motor shaft 62 and the drive shaft 65, the front-to-back length of the power transmission mechanism 70 is reduced, and the power unit 30 is made smaller.

[0026] A cylindrical cover 42 bulges out from the outer surface of the gear case 41, and in a side view, the motor shaft 62 and the first intermediate shaft 71 are located on the cylindrical cover 42. The first intermediate shaft 71 is equipped with the first intermediate gear 74, which is the upstream of the multiple intermediate gears in the power transmission direction. The first intermediate gear 74 is formed to be the largest in diameter, and in a side view, most of the first intermediate gear 74 overlaps with the cylindrical cover 42. Because the first intermediate gear 74 is installed to the side of the cylindrical cover 42, the third to fifth intermediate gears 76-78 are installed at a lower position in the vehicle width direction than the cylindrical cover 42, making it easier to install the drive sprocket 67 inward in the vehicle width direction.

[0027] Furthermore, a protruding portion 43 extends rearward from the cylindrical cover 42 of the gear case 41, and the second and third intermediate shafts 72 and 73 and the drive shaft 65 are installed on the protruding portion 43 along the outer circumference of the cylindrical cover 42. The third to fifth intermediate gears 76-78, the drive gear 66 (see Figure 7), and the drive sprocket 67 (see Figure 7) are compactly installed around the cylindrical cover 42, resulting in a miniaturized power unit 30. In this embodiment, not only the motor shaft 62 and the drive shaft 65, but also the first intermediate shaft 71 and the third intermediate shaft 73 are at the same height, but it is not necessary for both shafts to be at exactly the same height; they may have an error that allows them to be considered to be at approximately the same height.

[0028] The power transmission mechanism 70 includes a fifth intermediate gear 78 to position the drive shaft 65 directly behind the motor shaft 62. To increase the overall reduction ratio of the power transmission mechanism 70, it is desirable to increase the number of teeth of the drive gear 66 compared to the fifth intermediate gear 78. However, this would increase the outer diameter of the drive gear 66, moving the drive shaft 65 further away from the motor shaft 62. Therefore, in this embodiment, by reducing the number of teeth of the drive gear 66 compared to the fifth intermediate gear 78, the outer diameter of the drive gear 66 is reduced, bringing the drive shaft 65 closer to the motor shaft 62 and thus miniaturizing the power unit 30.

[0029] As shown in Figures 7 and 8, in a top view, the mating surface 45 of the gear case 41 and the gear case cover 51 is inclined inward in the vehicle width direction toward the rear. The output gear 63, the first to third intermediate gears 74-76, and the drive sprocket 67 are installed on the outside in the vehicle width direction of the mating surface 45. The fourth and fifth intermediate gears 77, 78 (see Figure 5) and the drive gear 66 are installed on the inside in the vehicle width direction of the mating surface 45. The output gear 63 and the first to third intermediate gears 74-76 that protrude from the mating surface 45 are housed in the upper part 52 of the gear case cover 51, and the drive sprocket 67 that protrudes from the mating surface 45 is exposed from the lower part 53 of the gear case cover 51.

[0030] The mating surface 45 is inclined inward in the vehicle width direction toward the rear, so that the rear of the gear case cover 51 is lower than the front. As a result, the rear of the gear case cover 51 is positioned inward in the vehicle width direction, and the drive sprocket 67 on the outside of the gear case cover 51 is positioned inward in the vehicle width direction. The drive sprocket 67 is positioned inward in the vehicle width direction than the output gear 63. The chain line of the drive chain 25 (see Figure 1) that is attached to the drive sprocket 67 is positioned inward in the vehicle width direction than the upper end of the gear case cover 51, thus making the power unit 30 smaller.

[0031] Inside the gear case cover 51, the output gear 63 is positioned furthest outward in the vehicle width direction, while the first to fifth intermediate gears 74-78 and the drive gear 66 are positioned inward in the vehicle width direction toward the downstream direction of power transmission. In the vehicle width direction, the first intermediate gear 74 is positioned at the same location as the output gear 63, the second and third intermediate gears 75 and 76 are positioned inward in the vehicle width direction than the first intermediate gear 74, and the fourth and fifth intermediate gears 77 and 78 and the drive gear 66 are positioned inward in the vehicle width direction than the third intermediate gear 76. This makes it easier to position the drive sprocket 67, which is coaxial with the drive gear 66, inward in the vehicle width direction.

[0032] When the gear case cover 51 is removed in a rear view, most of the gears are visible. In a rear view, the first to third intermediate gears 74-76 are positioned outside the outer surface of the cylindrical cover 42, while the fourth and fifth intermediate gears 77, 78 and the drive gear 66 are positioned inside the outer surface of the cylindrical cover 42 in the vehicle width direction. The fourth and fifth intermediate gears 77, 78 and the drive gear 66 overlap the cylindrical cover 42. This makes it easier to position the drive sprocket 67, which is coaxial with the drive gear 66, inside the vehicle width direction. In addition, the width of the power transmission mechanism 70 is reduced, and the power unit 30 is made smaller.

[0033] As described above, with the power unit 30 of this embodiment, the power transmission mechanism 70 is made compact by providing the output gear 63 and drive sprocket 67 on one side in the vehicle width direction. Furthermore, the drive sprocket 67, which is on the outside of the gear case cover 51, is positioned further inward in the vehicle width direction than the output gear 63, which is on the inside of the gear case cover 51, thus suppressing the outward protrusion of the drive sprocket 67 in the vehicle width direction. The chain line of the drive sprocket 67 of the power unit 30 and the drive chain 25 wrapped around the driven sprocket 24 of the rear wheel 19 is moved inward in the vehicle width direction, resulting in a smaller electric vehicle and power unit 30.

[0034] In this embodiment, the power transmission mechanism is composed of a gear train, but any power transmission mechanism that can transmit power from the motor shaft to the drive shaft is acceptable.

[0035] Furthermore, in this embodiment, the mating surface between the gear case and the gear case cover is inclined inward in the vehicle width direction toward the rear when viewed from above, but the mating surface does not need to be inclined if the drive sprocket can be installed inward in the vehicle width direction relative to the output gear.

[0036] Furthermore, in this embodiment, the power transmission mechanism has three intermediate shafts and five intermediate gears, but the number, installation location, size, etc., of the intermediate shafts and intermediate gears of the power transmission mechanism are not particularly limited.

[0037] Furthermore, in this embodiment, the drive gear has fewer teeth than the fifth intermediate gear, but if the drive shaft can be installed behind the motor shaft, the drive gear may have more teeth than the fifth intermediate gear.

[0038] Furthermore, the power unit of this embodiment is not limited to the saddle-type electric vehicle described above, but may also be used in other saddle-type electric vehicles. Note that the term "saddle-type electric vehicle" is not limited to electric vehicles in which the driver straddles the seat, but also includes scooter-type electric vehicles in which the driver does not straddle the seat.

[0039] As described above, the first embodiment is a power unit (30) in which a gear case (41) is provided on one side in the vehicle width direction of a motor case (left motor case 39, right motor case 32), and the opening of the gear case is covered from the outside in the vehicle width direction by a gear case cover (51). The power unit (30) comprises a motor shaft (62) protruding from the motor case side to the gear case side, a drive shaft (65) protruding outward in the vehicle width direction from the gear case cover, and a power transmission mechanism (70) that transmits power from the motor shaft to the drive shaft. An output gear (63) is fixed to the motor shaft inside the gear case cover, and a drive sprocket (67) is fixed to the drive shaft outside the gear case cover, with the drive sprocket positioned further inward in the vehicle width direction than the output gear. With this configuration, the power transmission mechanism can be made compact by providing the output gear and drive sprocket on one side in the vehicle width direction. Furthermore, the drive sprocket on the outside of the gear case cover is positioned further inward in the vehicle width direction than the output gear inside the gear case cover, thus reducing the outward protrusion of the drive sprocket in the vehicle width direction. The chain line of the drive chain, which is wrapped around the drive sprocket of the power unit and the driven sprocket of the drive wheel, is moved further inward in the vehicle width direction, resulting in a smaller electric vehicle and power unit.

[0040] In the second embodiment, as in the first embodiment, the mating surface (45) of the gear case and the gear case cover is inclined inward in the vehicle width direction toward the rear, so that the drive sprocket is positioned behind the output gear. With this configuration, the rear part of the gear case cover is moved inward in the vehicle width direction, making it easier to install the drive sprocket on the outside of the gear case cover inward in the vehicle width direction.

[0041] In the third embodiment, as in the first and second embodiments, the power transmission mechanism has multiple intermediate shafts (first to third intermediate shafts 71 to 73) each provided with multiple intermediate gears (first to fifth intermediate gears 74 to 78), and inside the gear case cover, the output gear is positioned furthest outward in the vehicle width direction, while the multiple intermediate gears are positioned inward in the vehicle width direction toward the downstream of the power transmission direction. This configuration makes it easier to position the drive sprocket inward in the vehicle width direction.

[0042] In the fourth embodiment, a cylindrical cover (42) bulges out from the outer surface of the gear case to cover the opening of the motor case, and the upstream intermediate gear (first intermediate gear 74) in the power transmission direction among the multiple intermediate gears has the largest diameter, and in a side view, the upstream intermediate gear overlaps the cylindrical cover. With this configuration, the large-diameter intermediate gear is installed to the side of the cylindrical cover, so that the intermediate gear behind the large-diameter intermediate gear is installed at a lower position in the vehicle width direction than the cylindrical cover, making it easier to install the drive sprocket further inward in the vehicle width direction.

[0043] The fifth embodiment is such that, in the third or fourth embodiment, the intermediate shafts (second and third intermediate shafts 72 and 73) and the drive shaft (65) located behind the intermediate shaft to which the uppermost intermediate gear is fixed are installed along the outer circumference of the cylindrical cover. With this configuration, some of the intermediate gears and drive sprockets are compactly installed around the cylindrical cover, resulting in a smaller power unit.

[0044] The sixth embodiment is one of the third to fifth embodiments, in which the motor shaft and drive shaft are positioned at the same height in a side view, and multiple intermediate shafts are positioned above the motor shaft and drive shaft. With this configuration, the front-to-back length of the power transmission mechanism is reduced, and the power unit is made smaller.

[0045] The seventh embodiment is one of the third to sixth embodiments, in which a drive gear (66) is provided on the drive shaft, and in a rear view, the intermediate gears downstream in the power transmission direction (the fourth and fifth intermediate gears 77 and 78) and the drive gear overlap the cylindrical cover. With this configuration, the drive sprocket, which is coaxial with the drive gear, can be easily installed on the inside in the vehicle width direction. In addition, the width of the power transmission mechanism is reduced, and the power unit can be made smaller.

[0046] The eighth embodiment is one of the third to seventh embodiments in which the drive gear has fewer teeth than the downstream intermediate gear (the fifth intermediate gear 78) in the power transmission direction. With this configuration, even if an intermediate gear is added to position the drive shaft at the rear, the smaller diameter of the drive gear allows the drive shaft to be brought closer to the motor shaft, resulting in a smaller power unit.

[0047] Although this embodiment has been described, other embodiments may include combinations of the above embodiment and its modifications, either entirely or partially.

[0048] Furthermore, the technology of the present invention is not limited to the embodiments described above, and may be modified, substituted, or transformed in various ways without departing from the spirit of the technical idea. Moreover, if the technical idea can be realized in a different way by advances in the technology or by other derived technologies, it may be implemented by that method. Accordingly, the claims cover all embodiments that may fall within the scope of the technical idea. [Explanation of Symbols]

[0049] 30: Power Unit 32: Right-side motor case (motor case) 39: Left motor case (motor case) 41: Gear Case 42: Cylindrical cover 45: The mating surface between the gear case and the gear case cover. 51: Gear case cover 62: Motor shaft 63: Output gear 65: Drive shaft 66: Drive Gear 67: Drive sprocket 70: Power transmission mechanism 71: First intermediate axis (intermediate axis) 72: Second intermediate axis (intermediate axis) 73: The third intermediate axis (intermediate axis) 74: First intermediate gear (intermediate gear) 75: Second intermediate gear (intermediate gear) 76: Third intermediate gear (intermediate gear) 77: Fourth intermediate gear (intermediate gear) 78: Fifth intermediate gear (intermediate gear)

Claims

1. A power unit in which a gear case is provided on one side of the motor case in the vehicle width direction, and the opening of the gear case is covered by a gear case cover from the outside in the vehicle width direction, The motor shaft protruding from the motor case side to the gear case side, The drive shaft protrudes outward in the vehicle width direction from the gear case cover, The system includes a power transmission mechanism that transmits power from the motor shaft to the drive shaft, The output gear is fixed to the motor shaft inside the gear case cover. The drive sprocket is fixed to the drive shaft on the outside of the gear case cover. A power unit characterized in that the drive sprocket is positioned further inward in the vehicle width direction than the output gear.

2. In a top view, the mating surface between the gear case and the gear case cover is inclined inward in the vehicle width direction towards the rear. The power unit according to claim 1, characterized in that the drive sprocket is positioned behind the output gear.

3. The power transmission mechanism has multiple intermediate shafts, each equipped with multiple intermediate gears. The power unit according to claim 1 or 2, characterized in that, inside the gear case cover, the output gear is positioned furthest outward in the vehicle width direction, and the plurality of intermediate gears are positioned inward in the vehicle width direction toward the downstream direction of power transmission.

4. A cylindrical cover bulges out from the outer surface of the gear case, covering the opening of the motor case. Of the aforementioned multiple intermediate gears, the intermediate gear furthest upstream in the power transmission direction has the largest diameter. The power unit according to claim 3, characterized in that the uppermost intermediate gear overlaps the cylindrical cover when viewed from the side.

5. The power unit according to claim 4, characterized in that the intermediate shaft and the drive shaft located behind the intermediate shaft to which the uppermost intermediate gear is fixed are installed along the outer circumference of the cylindrical cover.

6. The power unit according to claim 5, characterized in that, in a side view, the motor shaft and the drive shaft are positioned at the same height, and the plurality of intermediate shafts are positioned above the motor shaft and the drive shaft.

7. The aforementioned drive shaft is provided with a drive gear. The power unit according to claim 6, characterized in that, in a rear view, the intermediate gear on the downstream side in the power transmission direction and the drive gear among the plurality of intermediate gears overlap the cylindrical cover.

8. The power unit according to claim 7, characterized in that the number of teeth of the drive gear is less than that of the downstream intermediate gear in the power transmission direction.

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