JP2008213775A - Drive of electric vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drive of an electric vehicle lowering the center of gravity of an electric motor relative to the vehicle, improving the cooling effect of the electric motor and lowering the position of its center of gravity relative to the vehicle even though it is arranged on the electric motor. <P>SOLUTION: This drive 23 of the electric vehicle 11 is constituted so that the electric motor 12 is arranged between a left wheel 71 and a right wheel 72 and driving force of the electric motor is transmitted to the wheels through a drive shaft 32. The electric motor 12 is arranged below the drive shaft 32, and a motor output shaft of the electric motor 12 is arranged so as to be in the vertical direction of the vehicle. The electric motor 12 is arranged under the drive shaft 32 and lowers the position of its center of gravity. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a driving device for an electric vehicle in which driving force of an electric motor is transmitted to a driving shaft of a wheel and the electric motor is included in a sprung mass.

In some electric vehicles, an electric motor is disposed between both wheels, and the electric motor is disposed at a height substantially the same as the height of the wheels, and travels through a planetary gear reducer (for example, patents). Reference 1).
JP 2003-254396 A (page 7, FIG. 2)

Next, Patent Document 1 will be briefly described.
FIG. 8 is an explanatory diagram of a conventional technique (Patent Document 1). In a conventional automobile drive device 201, a motor 202 is disposed between a front wheel 203 and a front wheel 203, and power is sequentially rotated on a rotating shaft of the motor 202. 204, the power is transmitted to the input shaft 206, the output shaft 207, and the rear wheel shaft 208 of the power transmission device 205 to travel.

  However, the automobile drive device 201 of Patent Document 1 has a problem that the mounting position of the motor 202 is high and the center of gravity of the motor 202 is high. Specifically, if the center of gravity of the motor 202 is on the rotating shaft 204, the center of gravity of the motor 202 is the same height as the rear wheel shaft 208, and the suspension spring corresponding to the force when the automobile bends (turns). There is a problem that the rate tends to increase and the ride quality is deteriorated.

In addition, there is a problem that the air flow that cools the motor 202 is poor and it is difficult to cool the motor 202.
Furthermore, the space occupied by the motor 202 becomes large, and there is a problem that it is difficult to increase the degree of design freedom. For example, when a control device or an auxiliary machine is arranged above the electric motor, there is a problem that the position of the center of gravity becomes high.

  An object of the present invention is to provide a drive device for an electric vehicle that lowers the center of gravity of the electric motor with respect to the vehicle, enhances the cooling effect of the electric motor, and is disposed on the electric motor but has a lower position of the center of gravity with respect to the vehicle.

  The invention according to claim 1 is an electric vehicle driving device in which an electric motor is disposed between wheels of the vehicle, and the driving force of the electric motor is transmitted to the wheels via the driving shaft, and the electric motor is disposed below the driving shaft, And it is arrange | positioned so that the motor output shaft of an electric motor may become the vertical direction of a vehicle.

  In the invention according to claim 1, since the electric motor is arranged below the drive shaft and the motor output shaft of the electric motor is arranged in the vertical direction of the vehicle, the electric motor is located below the drive shaft. There is an advantage that the center of gravity of the motor can be lowered to lower the center of gravity of the motor relative to the vehicle.

  In addition, since the electric motor is disposed below the drive shaft and the motor output shaft of the electric motor is disposed in the vertical direction of the vehicle, the electric motor easily hits traveling wind flowing through the bottom of the vehicle. There is an advantage that the cooling effect can be enhanced.

  Further, since the electric motor is arranged below the drive shaft and the motor output shaft of the electric motor is arranged in the vertical direction of the vehicle, the arrangement position of the electric motor is lowered from the drive shaft and arranged on the electric motor. For example, there is an advantage that the position of the center of gravity of the control device and other auxiliary machines with respect to the vehicle can be lowered.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a perspective view for explaining an outline of a drive device (first embodiment) for an electric vehicle according to the present invention.
The electric vehicle 11 drives the rear wheel 13 with an electric motor 12 disposed later.
Specifically, the vehicle body 15, the underbody 16 that forms the floor of the vehicle body 15, the passenger compartment 17, the accelerator pedal 21 disposed in the driver seat of the passenger compartment 17, the electric motor 12 corresponding to the accelerator pedal 21, and the electric motor 12 An electric rear wheel drive device 23 that is a drive device connected to the vehicle, a control device 24 that controls the motor torque of the electric motor 12 based on accelerator information of the accelerator pedal 21, and a sensor that detects the state of the vehicle. And an auxiliary machine 25.

FIG. 2 is a sectional view taken along line 2-2 of FIG. 1 (first embodiment). This will be described with reference to FIG.
The electric rear wheel drive device 23 includes a shaft housing 31 that is supported on the vehicle body 15 via a rear wheel suspension device (not shown), and a drive shaft 32 that is rotatably mounted in the shaft housing 31. A reduction gear 33 that transmits a driving force to the drive shaft 32, and the reduction gear 33 is connected to the electric motor 12.

The drive shaft 32 includes a left rear drive shaft 35 connected to the speed reducer 33 and a right rear drive shaft 36.
The left rear drive shaft 35 includes a left universal joint 37 on the wheel side, a left axle 38 is connected to the left universal joint 37, and the rear wheel 13 is attached to the left axle 38 via a hub.

  The right rear drive shaft 36 includes a right universal joint 41 on the wheel side, a right axle 42 is connected to the right universal joint 41, and the rear wheel 13 is attached to the right axle 42 via a hub.

In the reduction gear 33, a planetary gear speed reducer 45 is provided in the electric motor 12, a first bevel gear 46 is integrally fitted to the planetary gear speed reducer 45, and a second bevel gear 47 is engaged with the first bevel gear 46. One end of the hollow shaft 48 is integrally fitted to the second bevel gear 47, the other end of the hollow shaft 48 is fitted to one side of the differential device 51, and the right rear drive shaft is connected to the other side of the differential device 51. 36 are integrally fitted and arranged in the shaft housing 31.
The differential device 51 has an existing configuration.

  The shaft housing 31 has a motor mounting opening 54 and a mounting boss 55 for mounting the electric motor 12 on the lower portion 53.

The electric motor 12 is a drive source of the rear wheel 13 and is a disk-shaped thin motor, and includes a stator 57, a rotor 58, and a motor housing 61.
The motor housing 61 has a flange portion 62 attached to the attachment boss 55 of the shaft housing 31, a connection sheet portion 63 brought into close contact with the motor attachment opening 54, and a cooling fin 64 formed on the outer surface.

  The cooling fin 64 is formed so as to correspond to the direction of the wind flowing in the bottom 66 (see FIG. 1) of the vehicle 11 (the direction of the arrow a1 in FIG. 3). As a result, the wind flowing through the bottom 66 of the vehicle 11 can be effectively used for air cooling.

The electric motor 12 incorporates a planetary gear speed reducer 45.
The planetary gear reducer 45 has an existing configuration, and each gear is attached to the rotor 58 of the electric motor 12 so that the reduction output shaft 67 is extended from the motor housing 61 of the electric motor 12. The first bevel gear 46 is fitted to the deceleration output shaft 67 (motor output shaft).
The planetary gear speed reducer 45 is an example, and a specific configuration is arbitrary.

  Here, the reduction output shaft 67 of the planetary gear speed reducer 45 also serves as the motor output shaft. When a speed reducer such as the planetary gear speed reducer 45 is provided outside the electric motor 12, the speed reduction output shaft 67 and the motor output shaft of the planetary gear speed reducer 45 are called separately.

  Specifically, the electric motor 12 is configured such that the central axis Cd of the drive shaft 32 is arranged in parallel to the vehicle width direction (X-axis direction) of the vehicle 11, and the motor of the electric motor 12 with respect to the central axis Cd of the drive shaft 32. The center axis Cm of the output shaft (deceleration output shaft 67) is orthogonal (Z-axis direction), and the center axis Cm of the motor output shaft (deceleration output shaft 67) of the electric motor 12 is arranged in the vertical direction (Z-axis direction). The electric motor 12 is disposed below the central axis Cd of the drive shaft 32 and is disposed substantially at the center between the left wheel 71 and the right wheel 72 of the rear wheel 13.

“Disposed below the central axis Cd of the drive shaft 32” means that the center of gravity G of the electric motor 12 is located below the central axis Cd and is located between the central axis Cd and the ground Gr (see FIG. 3). It is in the state where it is arranged.
The configuration of the electric motor 12 is an example, and an existing configuration may be used.

Next, the operation of the electric vehicle drive device (first embodiment) of the present invention will be described.
FIG. 3 is a diagram illustrating the mechanism of the drive device (first embodiment) for the electric vehicle. This will be described with reference to FIGS.
In the drive device (electric rear wheel drive device) 23, when the electric motor 12 operates, the motor torque of the electric motor 12 is transmitted to the drive shaft 32 via the reduction gear 33 (including the planetary gear reduction gear 45), and the left wheel 71 and the right wheel 72 can be driven.

  In the drive device (first embodiment) 23, since the motor 12 is attached to the lower portion 53 of the shaft housing 31 of the drive shaft 32 that drives the left wheel 71 and the right wheel 72, the center of gravity G of the motor 12 is driven. The height Hg of the center of gravity G of the motor 12 below the shaft 32 can be made lower than the height Hd of the drive shaft 32 by a height Hs, and the center of gravity of the motor 12 relative to the vehicle 11 can be lowered. .

In the drive device (first embodiment) 23, when the motor 12 is attached to the lower portion 53 of the shaft housing 31 of the drive shaft 32, the motor 12 becomes substantially the same as the height Hu of the underbody 16 that forms the floor of the vehicle body 15. The traveling wind A flowing on the lower surface of the underbody 16 (the bottom 66 of the vehicle 11) flows along the underbody 16 and then flows along the electric motor 12. As a result, the electric motor 12 is easily cooled by the traveling wind that flows through the bottom 66 of the vehicle body 15 or the wind that passes when the motor 12 is stopped.
That is, the cooling effect of the drive motor 12 disposed between the left wheel 71 and the right wheel 72 can be enhanced.

In the drive device (first embodiment) 23, when the electric motor 12 is arranged below the drive shaft 32, the space above the drive shaft 32 is made wider than when the electric motor 12 is arranged on the drive shaft 32. Can be placed on the electric motor 12 in a wide space, for example, the control device 24 and other auxiliary devices can be placed, and the center of gravity of the control device 24 and other auxiliary devices with respect to the vehicle 11 can be lowered. can do.
Moreover, the vehicle compartment 17 on the electric motor 12 can be enlarged.

The cooling fin 64 is disposed at a height Hf that is substantially the same as the height Hu of the underbody 16 that forms the floor. As a result, the wind flowing through the bottom 66 of the vehicle 11 can be effectively used for air cooling.
The cooling fin 64 is disposed at substantially the same height as the height Hu of the underbody 16 forming the floor. As a result, even if the electric motor 12 is disposed below the drive shaft 32, the resistance against wind flowing through the bottom 66 of the vehicle 11 can be reduced.

Next, “another embodiment” of the drive device for an electric vehicle according to the present invention will be described.
FIG. 4 is a diagram for explaining the second embodiment and corresponds to FIG. The same configurations as those in the embodiment shown in FIGS. 1 to 3 are denoted by the same reference numerals and description thereof is omitted.
The drive device 23B according to the second embodiment includes an electric motor 12B and a planetary gear speed reducer 45B disposed outside the electric motor 12B.

The electric motor 12 </ b> B is disposed at substantially the same position as the electric motor 12 of the first embodiment, and the first bevel gear 46 is fitted to the motor output shaft 74.
In addition, although the cooling fin is not shown in the electric motor 12 </ b> B, the cooling fin may naturally be formed in the same manner as the cooling fin 64.

  The planetary gear speed reducer 45 </ b> B is included in the speed reduction device 33 </ b> B, and the input gear 75 is integrally fixed to the hollow shaft 48 rotated by the second bevel gear 47 meshed with the first bevel gear 46. The gear 76 meshes, the revolution gear 76 meshes with the output gear (sun gear) 77, and the output gear (sun gear) 77 transmits power to the differential device 51. That is, the drive device 23B using the electric motor 12B as a drive source drives the rear wheel 13.

  The drive device 23B of the second embodiment exhibits the same effects as the drive device 23 of the first embodiment.

FIG. 5 is a diagram for explaining the third embodiment and corresponds to FIG. The same configurations as those in the embodiment shown in FIGS. 1 to 3 are denoted by the same reference numerals and description thereof is omitted.
The drive device 23C of the third embodiment is symmetrical with respect to the symmetry center line S, and includes the electric motor 12 that drives the left wheel 71 and the electric motor 12 that drives the right wheel 72. Features. That is, the left wheel 71 is independently driven by the left electric motor 12, and the right wheel 72 is independently driven by the right electric motor 12.

The left reduction gear 33C has a second bevel gear 47 that drives only the left rear drive shaft 35C fixed to the left rear drive shaft 35C.
The right reduction gear 33C has a second bevel gear 47 that drives only the right rear drive shaft 36C fixed to the right rear drive shaft 36C.

  The drive device 23C of the third embodiment exhibits the same effect as the drive device 23 of the first embodiment.

FIG. 6 is a diagram for explaining the fourth embodiment and corresponds to FIG. The same configurations as those in the embodiment shown in FIGS. 1 to 3 are denoted by the same reference numerals and description thereof is omitted.
The drive device 23D of the fourth embodiment is symmetrical with respect to the symmetry center line S, and includes an electric motor 12D that drives the left wheel 71 and an electric motor 12D that drives the right wheel 72. Features.
The electric motor 12D is the same as the electric motor 12B.

  The left reduction gear 33D has a second bevel gear 47 that drives only the left rear drive shaft 35D fixed to the left rear drive shaft 35D, and the output gear (sun gear) 77 is fitted to the left rear drive shaft 35D. Yes.

  The right reduction gear 33D has a second bevel gear 47 that drives only the right rear drive shaft 36D fixed to the right rear drive shaft 36D, and the right rear drive shaft 36D is fitted to the output gear (sun gear) 77. Yes.

  The drive device 23D of the fourth embodiment exhibits the same effect as the drive device 23 of the first embodiment.

FIG. 7 is a diagram for explaining the fifth embodiment and corresponds to FIG. The same configurations as those in the embodiment shown in FIGS. 1 to 3 are denoted by the same reference numerals and description thereof is omitted.
The drive device 23E according to the fifth embodiment includes a reduction gear 33E and an electric motor 12E.

  The reduction gear 33E transmits a driving force to the drive shaft 32E, and the first bevel gear 46, the second bevel gear 47, the hollow shaft 48, the differential device 51, and the differential device 51 that are fitted to the electric motor 12E. Left and right eccentric speed reduction mechanisms 81 and 81 connected to each other.

The left eccentric speed reduction mechanism 81 offsets the central shaft 82 of the drive shaft 32E upward by a distance Z1 with respect to the axis Cs of the left rear drive shaft 35. The first gear 83 formed on the central shaft 82 and the second gear 84 meshed with the first gear 83 are provided, and the left rear drive shaft 35 is formed on the second gear 84.
The right eccentric speed reduction mechanism 81 is the same as the left eccentric speed reduction mechanism 81.
The electric motor 12 </ b> E is a disk type motor, and a rotor 87 is disposed on a disk rotor member 86.

The drive device 23E of the fifth embodiment exhibits the same effect as the drive device 23 of the first embodiment.
Moreover, in the drive device 23E of the fifth embodiment, a large output can be ensured by employing the large disk type motor 12E.
Furthermore, in the drive device 23E of the fifth embodiment, the center of gravity of the electric motor 12E with respect to the vehicle 11 can be greatly lowered by adopting the disk type motor 12E.
In addition, the distance from the ground Gr to the electric motor 12E can be increased while lowering the center of gravity of the electric motor 12E with respect to the vehicle 11.

In addition, although the drive device of the electric vehicle of this invention was employ | adopted for the rear-wheel drive in embodiment, it may be employ | adopted for front-wheel drive and naturally may be employ | adopted for AWD (four-wheel drive).
An electric vehicle is a vehicle (including a part) driven by an electric motor, and includes a combination with an internal combustion engine (including a plug-in), a fuel cell vehicle, and an electric vehicle.
Although the bevel gear is used, a gear other than the bevel gear may be used. For example, a screw gear and a hypoid gear pair.

  The drive device for an electric vehicle according to the present invention is suitable for a drive device using a thin motor.

It is a perspective view explaining the outline | summary of the drive device (1st Embodiment) of the electric vehicle of this invention. FIG. 2 is a sectional view taken along line 2-2 of FIG. 1 (first embodiment). It is a figure explaining the mechanism of the drive device (1st Embodiment) of an electric vehicle. It is a figure explaining 2nd Embodiment. It is a figure explaining 3rd Embodiment. It is a figure explaining 4th Embodiment. It is a figure explaining 5th Embodiment. It is explanatory drawing of a prior art (patent document 1).

Explanation of symbols

11 ... Electric vehicle (vehicle)
12 ... Electric motor 15 ... Drive shaft 32
23 ... Drive device (electric rear wheel drive device)
71: Left wheel of rear wheel 72 ... Right wheel of rear wheel 74 ... Motor output shaft

Claims (1)

In an electric vehicle drive device in which an electric motor is disposed between wheels of a vehicle and the driving force of the electric motor is transmitted to the wheels via a drive shaft,
The electric motor is disposed below the drive shaft, and the motor output shaft of the electric motor is disposed in a vertical direction of the vehicle.

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