JP2013055804A - In-wheel motor drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an in-wheel motor drive device that can enhance the effect of cooling an electric motor and also improve lubricity of a deceleration mechanism.SOLUTION: A drive axle 28 for wheel drive is disposed coaxially with a rotor shaft 25 of an electric motor 16 incorporated into a motor case 10. A planet gear type deceleration mechanism 45 that decelerates the rotation of the rotor shaft 25 and transmits it to the drive axle 28 is disposed between the drive axle 28 and the rotor shaft 25 of the electric motor 16. An airtight deceleration mechanism housing space 42 for housing the deceleration mechanism 45 is disposed on the outside of an end plate 12 of the motor case 10. Lubricating oil is stored in the deceleration mechanism housing space 42. Cooling oil having a lower viscosity than the lubricating oil is stored in a motor housing space 15 in the motor case 10. Thus, different types of oils are respectively used for lubricating the deceleration mechanism 45 and for cooling the electric motor 16.

Description

  The present invention relates to an in-wheel motor drive device for driving drive wheels of an automobile.

  FIG. 1 shows an outline of an in-wheel electric vehicle. In this electric vehicle, a motor drive device A using an electric motor as a drive source is housed inside a pair of left and right rear wheels 1 as drive wheels, and each of the pair of rear wheels 1 is independently provided by the motor drive device A. To drive.

  The motor drive device A employed in the in-wheel electric vehicle as described above includes an electric motor, a speed reduction mechanism that reduces the rotation of the rotor shaft of the electric motor, and a drive that is rotationally driven by an output from the speed reduction mechanism. And the rear wheels are driven by the drive axle.

  In the motor drive device A, it is required to make the axial length compact because it is housed inside the rear wheel. In the motor drive device described in Patent Document 1, a planetary gear type reduction mechanism is disposed inside the rotor of the electric motor so as to reduce the axial length of the motor drive device.

  Here, since the electric motor generates heat due to its rotation, it needs to be cooled, and in the planetary gear type reduction mechanism, the reduction in durability due to wear of the gear is suppressed, and abnormal noise due to meshing is suppressed. Lubrication is necessary to suppress the occurrence.

  Therefore, in the motor drive device described in Patent Document 1, oil is accommodated in a motor case that accommodates the electric motor, the electric motor is cooled by the oil, and the planetary gear type reduction mechanism is lubricated. ing.

Japanese Patent No. 4286390

  By the way, in the motor drive device described in Patent Document 1, as described above, the electric motor is cooled and the speed reduction mechanism is lubricated by a kind of oil contained in the motor case. There is a problem like this.

  That is, when the oil amount increases, the rotational resistance of the electric motor increases and the efficiency decreases. Conversely, when the oil amount is small, the lubricity of the speed reduction mechanism decreases, and the decrease in durability can be suppressed. become unable.

  Moreover, if oil with high viscosity is used as the oil, the oil viscosity becomes rotational resistance of the electric motor, and the efficiency of the electric motor is reduced. If oil with low viscosity is used, the lubricity of the speed reduction mechanism is reduced. It will be.

  Further, metal powder due to wear of gears in the speed reduction mechanism is mixed into the oil, and the electric motor is cooled by the mixed oil of the metal powder, so that the metal powder enters the electric motor and adversely affects the electric motor. Become.

  The subject of this invention is providing the in-wheel motor drive device which can aim at the improvement of the lubricity of a speed-reduction mechanism while being able to raise the cooling effect of an electric motor.

  In order to solve the above-mentioned problems, the present invention has a motor case fixed to the vehicle body, a stator fixed in the motor case, and a rotor incorporated in the stator, on the central axis of the rotor. An electric motor provided with a rotor shaft, a drive axle for driving wheels arranged coaxially with the rotor shaft, and a planetary gear type that decelerates the rotation of the rotor shaft of the electric motor and outputs it to the drive axle In the in-wheel motor drive device, which is configured to cool the electric motor and lubricate the speed reduction mechanism with stored oil, a hermetically sealed type housing the speed reduction mechanism outside the end plate of the motor case. A speed reduction mechanism accommodating space is provided, lubricating oil is accommodated in the speed reducing mechanism accommodating space, and the lubricating oil is accommodated in the motor accommodating space inside the motor case. Houses the lower cooling oil viscosity than Le, it was adopted configuration using heterologous oil for cooling the lubricating and electric motor speed reduction mechanism.

Here, by using industrial lubricating oil with ISO viscosity grade number VG22 or higher as the lubricating oil, the kinematic viscosity at 40 ° C. of these lubricating oils is 22 mm ² / s or higher, so the speed reduction mechanism is good. Can be lubricated. Also, by using industrial lubricating oil with ISO viscosity grade number VG15 or lower as the cooling oil, the kinematic viscosity at 40 ° C. of these lubricating oils is 15 mm ² / s or lower. It can be cooled effectively.

  As described above, an appropriate amount of oil suitable for lubrication of the speed reduction mechanism is stored in the speed reduction mechanism accommodation space by providing the speed reduction mechanism accommodation space for accommodating the speed reduction mechanism outside the end plate of the motor case that accommodates the electric motor. In addition, an appropriate amount of oil for cooling the electric motor can be stored in the motor housing space.

  As a result, the speed reduction mechanism can be well lubricated and can be effectively cooled without reducing the efficiency of the electric motor.

  Here, by forming drain holes in the lower part of the peripheral wall of the speed reduction mechanism housing space and the lower part of the peripheral wall of the motor housing space, and closing the drain hole with a removable drain plug, oil exchange due to oil deterioration or the like Can be made possible.

  In addition, a cylindrical bulging portion that enters the inside of the rotor is provided at the center of the end plate of the motor case, and a vehicle body mounting flange is provided on a bearing outer ring of a wheel bearing that rotatably supports the drive axle, and an outer surface of the end plate of the motor case The outer peripheral portion of the vehicle body mounting flange is fixed to the vehicle body, the opening of the bulging portion is closed with the vehicle body mounting flange, and a reduction mechanism housing space is formed inside the bulging portion, thereby forming a rotor of the electric motor. Since the speed reduction mechanism is disposed inside the motor, a compact in-wheel motor drive device having an axial length can be obtained.

  In the reduction gear device according to the present invention, as described above, the reduction mechanism accommodation space for accommodating the reduction mechanism is provided outside the end plate of the motor case that accommodates the electric motor, and the lubricating oil is accommodated in the reduction mechanism accommodation space. The motor housing space in the motor case accommodates cooling oil having a viscosity lower than that of the lubricating oil, so that the speed reduction mechanism can be well lubricated, and the efficiency of the electric motor is not reduced. It can be cooled effectively.

Schematic diagram of an electric vehicle The front view which shows embodiment of the in-wheel motor drive device which concerns on this invention 2 is a longitudinal sectional view

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 2, an in-wheel motor drive device A according to the present invention is provided inside the wheel 2 of the drive wheel 1.

  As shown in FIG. 3, the in-wheel motor drive device A has a motor case 10. The motor case 10 includes a cylindrical case body 11 having an end plate 12 and a cover 13 that closes an opening of the case body 11.

  The cover 13 is formed with a cylindrical portion 13 a that is fitted into the open end of the case main body 11, and the fitting surface between the cylindrical portion 13 a and the case main body 11 is sealed by incorporating a seal ring 14.

  The motor case 10 is fixed to the vehicle body. The interior of the motor case 10 is a motor housing space 15, and an electric motor 16 is incorporated in the motor housing space 15.

  The electric motor 16 has a stator 17 fixed to the motor case 10 and a rotor 18 incorporated therein, and the rotor 18 is rotated by energization of the coil 17 a of the stator 17.

  The rotor 18 has a disk portion 19 at an axial end facing the cover 13, and a plurality of holes 20 are formed in the disk portion 19 at equal intervals in the circumferential direction, with a boss portion 21 at the center. Is provided.

  The end plate 12 of the case body 11 is formed with a cylindrical bulging portion 22 that enters the inside of the rotor 18, and the boss portion 21 is inserted into an insertion hole 23 formed at the center of the bulging portion 22. The motor housing space 15 is hermetically sealed by a seal member 24 incorporated between the outer diameter surface of the boss portion 21 and the inner diameter surface of the insertion hole 23.

  A rotor shaft 25 is inserted through the boss portion 21 of the rotor 18. The rotor shaft 25 is prevented from rotating on the rotor 18 by a key 26 and rotates together with the rotor 18.

  A wheel bearing 27 is provided on the outer side of the motor case 10, and a drive axle 28 that rotationally drives the drive wheel 1 is rotatably supported by the wheel bearing 27.

  The wheel bearing 27 has a bearing outer ring 29 and an inner member 30 incorporated inside thereof. A vehicle body mounting flange 31 is formed on the outer diameter surface of the bearing outer ring 29. The vehicle body mounting flange 31 is abutted against the outer surface of the end plate 12 of the motor case 10, and is tightened by a bolt 32 screwed into the end plate 12. The motor case 10 is attached.

  The inner member 30 includes a hub ring 33 and a bearing inner ring 34 provided on an inner side end of the hub ring 33, and the bearing inner ring 34 is a small-diameter shaft formed at an inner side end of the hub ring 33. It is fitted to the portion 33a. Each of the hub wheel 33 and the bearing inner ring 34 is rotatably supported by a rolling element 35 incorporated between the bearing outer ring 29 and the seal member 36 incorporated on the outer side of the rolling element 35. And both end openings of the bearing space formed at the opposite ends of the inner member 30 are closed.

  The hub wheel 33 is provided with a wheel mounting flange 37 on the outer periphery of the outer end of the bearing outer ring 29, and a nut 39 is screwed to each of a plurality of bolts 38 provided on the wheel mounting flange 37. The brake rotor 40 and the wheel 2 of the driving wheel 1 are attached to the wheel attachment flange 37 by engaging the nut 39.

  The drive axle 28 is inserted inside the hub wheel 33 and is prevented from rotating on the hub wheel 33 by engagement by the serration 41. By attaching the wheel bearing 27 supporting the drive axle 28 to the end plate 12, the opening of the bulging portion 22 provided in the end plate 12 is closed to form a sealed space inside, and the sealed space is decelerated. A mechanism accommodating space 42 is provided.

  The drive axle 28 is arranged coaxially with the rotor shaft 25, and a shaft insertion hole 43 is formed at the end of the drive axle 28 facing the rotor shaft 25. A bearing 44 is incorporated in the shaft insertion hole 43, and the end of the rotor shaft 25 is rotatably supported by the bearing 44.

  Between the rotor shaft 25 and the drive axle 28, a speed reduction mechanism 45 that decelerates the rotation of the rotor shaft 25 and transmits it to the drive axle 28 is provided. The speed reduction mechanism 45 includes a sun gear 46 provided at the shaft end portion of the rotor shaft 25, an internal gear 47 fitted and fixed to the inner diameter surface of the bulging portion 22, and an inner circumference of the internal gear 47. A planetary gear type comprising a tooth and a planetary gear 48 meshing with each of the outer teeth on the outer periphery of the sun gear 46, and the planetary gear 48 is a disk provided on the outer periphery of the inner side end of the drive axle 28. Is supported so as to be rotatable about a gear shaft 50 supported by a carrier 49 having a shape.

  In the in-wheel motor drive device having the above configuration, when the rotor 18 is rotationally driven by energization of the coil 17a of the stator 17, the rotor shaft 25 rotates together with the rotor 18.

  The rotation of the rotor shaft 25 is decelerated by the planetary gear type reduction mechanism 45 and transmitted to the drive axle 28, and the drive wheel 1 is rotationally driven by the drive axle 28.

  Due to the driving of the driving wheel 1 as described above, the electric motor 16 is loaded and generates heat, and the speed reduction mechanism 45 is of a planetary gear type. descend. In order to suppress the occurrence of such inconvenience, as shown in FIG. 3, oil is stored in the motor housing space 15, and the electric motor 16 is cooled with the stored oil. Further, oil is stored in the speed reduction mechanism accommodation space 42, and the speed reduction mechanism 45 is lubricated with the stored oil.

  Here, if the cooling oil and the lubricating oil are of the same type, the efficiency of the electric motor 16 is affected, or the lubrication of the speed reduction mechanism 45 is affected.

  Therefore, in the embodiment, oil having a low viscosity is accommodated in the motor accommodating space 15 to cool the electric motor 16. As an oil suitable for cooling, an industrial lubricating oil having ISO viscosity grade number VG15 or less can be mentioned.

  On the other hand, high-viscosity oil is accommodated in the speed reduction mechanism accommodation space 42 to lubricate the speed reduction mechanism 45. As an oil suitable for lubrication, an industrial lubricating oil having ISO viscosity grade number VG22 or higher can be exemplified.

If the amount of oil accommodated in the motor accommodating space 15 increases more than necessary, the rotational resistance of the electric motor 16 increases and efficiency decreases. Therefore, the oil amount of the cooling oil is set such that the lower part of the outer periphery of the rotor 18 is immersed, as indicated by l ₁ in FIG.

On the other hand, when the amount of oil accommodated in the speed reduction mechanism accommodation space 42 is less than necessary, the speed reduction mechanism 45 cannot be effectively lubricated. Therefore, the oil amount of the lubrication oil, as shown by l ₂ of FIG. 3, are almost the same level as the central axis of the rotor shaft 25.

  In the embodiment, as described above, the speed reduction mechanism accommodation space 42 for accommodating the speed reduction mechanism 45 is formed outside the end plate 12 of the motor case 10 for accommodating the electric motor 16, and the speed reduction mechanism accommodation space 42 and the motor are formed. Since the storage space 15 is partitioned by the end plate 12, an appropriate amount of oil suitable for lubricating the speed reduction mechanism 45 can be stored in the speed reduction mechanism storage space 42, and the motor storage space 15 can be stored in the motor storage space 15. An appropriate amount of oil suitable for cooling the electric motor 16 can be stored.

  As a result, the speed reduction mechanism 45 can be lubricated satisfactorily and can be effectively cooled without reducing the efficiency of the electric motor 16.

  Here, as shown in FIG. 3, a drain hole 51 is formed in each of the lower part of the peripheral wall of the speed reduction mechanism housing space 42 and the lower part of the peripheral wall of the motor housing space 15, and the drain hole 51 is closed by a removable drain plug 52. In this case, it is possible to change the oil due to deterioration of the oil or the like.

DESCRIPTION OF SYMBOLS 10 Motor case 15 Motor accommodation space 16 Electric motor 17 Stator 18 Rotor 22 Expansion part 25 Rotor shaft 27 Wheel bearing 28 Drive axle 29 Bearing outer ring 31 Car body mounting flange 42 Deceleration mechanism accommodation space 45 Deceleration mechanism 51 Drain hole 52 Drain plug

Claims (4)

An electric motor having a motor case fixed to the vehicle body, a stator fixed in the motor case and a rotor incorporated in the stator, and a rotor shaft provided on a central axis of the rotor, and the rotor A drive axle for driving a wheel disposed coaxially with the shaft, and a planetary gear type reduction mechanism that decelerates the rotation of the rotor shaft of the electric motor and outputs it to the drive axle. In-wheel motor drive device designed to perform cooling and lubrication of the speed reduction mechanism,
A sealed reduction mechanism accommodation space for accommodating the reduction mechanism is provided outside the end plate of the motor case, lubricating oil is accommodated in the reduction mechanism accommodation space, and the motor accommodation space inside the motor case is accommodated. An in-wheel motor drive device comprising: a cooling oil having a viscosity lower than that of the lubricating oil, and different types of oil used for lubricating the speed reduction mechanism and cooling the electric motor.   The in-wheel motor drive device according to claim 1, wherein the lubricating oil has an ISO viscosity grade number VG22 or higher and the cooling oil has an ISO viscosity grade number VG15 or lower.   The in-wheel motor drive device of Claim 1 or 2 which formed the drain hole obstruct | occluded by the drain plug which can be attached or detached to each of the surrounding wall lower part of the said deceleration mechanism accommodation space, and the surrounding wall lower part of a motor accommodation space.   A cylindrical bulging portion that enters the inside of the rotor is provided at a central portion of the end plate of the motor case, a vehicle body mounting flange is provided on a bearing outer ring of a wheel bearing that rotatably supports the drive axle, and an end of the motor case The opening of the said bulging part is obstruct | occluded by fixation of the outer peripheral part of the vehicle body mounting flange with respect to a board outer surface, The deceleration mechanism accommodation space was formed inside the bulging part. In-wheel motor drive device.

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