JP2012241820A - Electric vehicle reduction differential gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric vehicle reduction differential gear including electric motors, a reduction part and a differential part, achieving lower cost and higher efficiency of the electric motor.SOLUTION: The electric vehicle reduction differential gear includes the electric motors 11, the reduction part 12 consisting of a small gear 31 and a large gear 32 in combination, and the differential part 13 constructed by a planetary gear mechanism. As the electric motors 11, a plurality of general motors are used in combination to achieve the lower cost. The number of the electric motors 11 to be driven is properly determined depending on a load to achieve the higher efficiency of the electric motors 11.

Description

  The present invention relates to a reduction differential for an electric vehicle using a motor as a drive source, and in particular, extends the travel distance per charge by reducing the cost and efficiency of an electric motor.

  A conventionally known reduction differential device for an electric vehicle is configured by a combination of an electric motor, a planetary gear type reduction unit, and a planetary gear type differential unit (Patent Documents 1 and 2). The speed reduction portion includes an input shaft integrated with a motor shaft of the electric motor, and a speed reduction portion sun gear is integrally provided on the input shaft in a coaxial state. The reduction part pinion gear is interposed between the reduction part sun gear and the reduction part ring gear fixed to the casing, and the reduction part carrier is integrated with the shaft of the pinion gear. A speed reduction part carrier is connected to the differential side ring gear and inputs a reduced driving force to the differential part.

  In the differential section, the reduction driving force is differentially distributed to two distribution members, that is, the differential section sun gear and the differential section carrier. A first output shaft is inserted and coupled to the center of the differential sun gear. The first output shaft passes coaxially through the inside of the speed reducer input shaft and the motor shaft integral therewith, and is connected to one of the wheels via a motor side constant velocity joint. In addition, a second output shaft is coupled to the speed reducer carrier, and the second output shaft is connected to the other wheel via a differential portion constant velocity joint.

JP-A-8-42656 JP-A-6-323404

  As described above, the conventional reduction gear unit uses a planetary gear mechanism in order to obtain a large reduction ratio, and has a configuration in which the motor shaft is inserted into the center of the reduction-side sun gear and integrally coupled. This planetary gear mechanism has a one-to-one configuration. As a result, one electric motor is used for one device.

  However, since the size and capability of the apparatus vary depending on the specifications, it is necessary to design a dedicated product for the electric motor according to the specifications of the apparatus, which is a factor that increases the manufacturing cost of the apparatus. In addition, since a single electric motor can handle all loads during vehicle travel, there is a problem in that the use efficiency of the motor is low.

  Further, in a small automobile or the like, there is a case where it is not necessary to use a planetary gear mechanism for the speed reduction portion because the speed reduction ratio of the speed reduction portion does not need to be set as high as the left.

  Accordingly, an object of the present invention is to improve the electric motor and the speed reduction unit to reduce the manufacturing cost, increase the use efficiency of the electric motor, and extend the travel distance per charge.

  In order to solve the above-mentioned problems, the present invention comprises a combination of an electric motor, a speed reduction unit and a differential unit, a casing housing each member, and first and second output shafts. Is decelerated in the decelerating unit and output to the differential unit, and the decelerated driving force is output to the two distributing members in accordance with the load in the differential unit, and one distributing member is the first output shaft. And the other distribution member is a reduction differential for an electric vehicle connected to the second output shaft, wherein a plurality of the electric motors are arranged around the first output shaft, and the reduction unit is an electric motor A small gear supported by the motor shaft and a large gear meshed with the small gear rotatably supported by the first shaft, and a part of the large gear is the difference Parts is obtained by the coupling configurations in the input gear.

  According to the above configuration, since a predetermined driving force is obtained by a plurality of electric motors, general-purpose motors can be used as the electric motors.

  Further, a configuration in which a one-way clutch for transmitting a driving force from the motor shaft but interrupting a driving force from the small gear is interposed between the motor shaft and the small gear can be adopted. When an appropriate number of electric motors among the plurality of electric motors is stopped, the motor shaft of the stopped electric motor is prevented from being rotated by the action of the one-way clutch.

  As described above, according to the present invention, since the electric motor is a general-purpose product, there is an advantage that the manufacturing cost of the apparatus is lower than that in the case of designing a dedicated product. In addition, by appropriately selecting the number of electric motors to be driven according to the load, the motor can be operated in an efficient region of the motor, and the power consumption is further reduced, so the travel distance per charge is increased. Can do.

FIG. 1 is a cross-sectional view of the first embodiment. 2 is a cross-sectional view taken along line X1-X1 of FIG. 3 is a cross-sectional view taken along line X2-X2 of FIG. 4 is a partially enlarged cross-sectional view of FIG. FIG. 5 is a sectional view taken along line X3-X3 in FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

[Embodiment 1]

  As shown in FIG. 1, the electric vehicle deceleration differential apparatus according to the first embodiment includes an electric motor 11 arranged in a coaxial state, a speed reduction unit 12 configured by a parallel shaft gear mechanism, and a planetary gear mechanism. The differential portion 13, the casing 14 housing the respective members, and a combination of a first output shaft 15 and a second output shaft 16 arranged on the same axis.

  The casing 14 includes a motor casing 14a that is closed at one end that houses the electric motor 11, a deceleration differential casing 14b that is open at both ends that houses the speed reduction portion 12 and the differential portion 13, and is interposed between the motor casing 14a and the speed reduction differential casing 14b. The partition casing 14c and the lid casing 14d for closing the other end of the speed-reducing differential casing 14b are combined and integrated.

  A boss 17 projecting inward in the axial direction is provided at the center of the closed end of the motor casing 14 a, and one end of the first output shaft 15 penetrates the inner diameter surface of the boss 17. Between the first output shaft 15 in the penetrating portion and the inner diameter surface of the boss 17, a first output shaft support bearing 18 formed of a rolling bearing is disposed inside, and an oil seal 19 is disposed outside. The oil seal 19 prevents the lubricating oil accumulated in the motor casing 14a from leaking out.

  In the motor casing 14a, four electric motors 11 are arranged at equal intervals in the circumferential direction, and each motor case 21 is fixed to the partition casing 14c. One end portion of the motor shaft 22 of each electric motor 11 is rotatably supported by each motor case 21 by a rolling bearing 23, and the other end portion penetrates the partition casing 14c. A rolling bearing 24 is interposed on the electric motor 11 side of the penetrating portion, and an oil seal 25 is interposed on the speed reduction unit 12 side.

  Inside the motor case 21, a rotor 26 is attached to the motor shaft 22, and a stator 27 diametrically opposed to the rotor 26 is fixed to the inner diameter surface of the motor case 21.

  Each of the electric motors 11 is a general-purpose motor, and the total driving force of the four units corresponds to the driving force of one conventional unit. The number of electric motors 11 to be driven from one to four is selectively determined according to the magnitude of the load by the vehicle control device. As a result, the electric motor 11 can be efficiently operated, and power consumption can be reduced.

  The first output shaft 15 passes through the center of the motor casing 14a and further passes through the center of the partition wall casing 14c. An oil seal 28 is interposed in the through portion of the partition casing 14c. The first output shaft 15 further passes through the center of the deceleration differential casing 14b and is rotatably inserted into a bearing hole 51 provided in the boss 50 of the carrier 43 of the differential section 13 described later.

  The speed reduction part 12 includes a small gear 31 attached to a small diameter part 22 a formed at the tip of each motor shaft 22 via a one-way clutch 30 (see FIG. 3), and an outer diameter of the first output shaft 15. It is constituted by a parallel shaft gear mechanism composed of a combination of external gear type large gears 32 that are rotatably mounted on the surface via a rolling bearing 29. A plurality of arms 33 (see FIG. 3) are provided radially on the boss of the large gear 32, and tip portions thereof are bent toward the differential portion 13 to form an annular portion 34. The reduction ratio of the speed reduction unit 12 is the ratio of the number of teeth of the small gear 31 and the large gear 32, and the driving force reduced by the reduction ratio is transmitted to the annular part 34.

  Instead of the arm 33, a disc portion may be provided integrally with the boss of the large gear 32, and the annular portion 34 may be formed by bending the outer peripheral portion of the disc portion toward the differential portion 13 side. .

  The one-way clutch 30 transmits the driving force from the motor shaft 22 to the small gear 31, but interrupts the transmission of torque in the opposite direction, and is known as a so-called free wheel.

  Instead of the external gear type large gear 32, an internal gear type large gear may be used. In that case, the internal gear type large gear is rotatably mounted on the inner diameter surface of the reduction differential casing 14b via a rolling bearing, and the small gears 31 are engaged with the inner diameter side.

  As shown in FIGS. 1 and 5, the differential portion 13 is constituted by a planetary gear mechanism, and is provided in a coaxial state on the inner diameter side of a ring gear 38 that is integrally provided on the inner diameter surface of the annular portion 34. A sun gear 39, double pinion type differential pinion gears 41a and 41b interposed between the ring gear 38 and the sun gear 39 and meshing with each other, pinion shafts 42a and 42b supporting these pinion gears 41a and 41b, and these pinion shafts 42a , 42b.

  The sun gear 39 is integrated with the first output shaft 15 by serration coupling, with the first output shaft 15 being inserted into a serration hole 45 provided at the center thereof. Further, the sun gear 39 is provided with an oil passage hole 56 formed by an arc-shaped long hole.

  The pinion gears 41a and 41b are gears having the same number of teeth and the same size. As shown in FIG. 5, the one pinion gear 41 a meshes with the ring gear 38 with one of the pinion gears 41 a having a larger PCD than the other pinion gear 41 b, and the pinion gear 41 b with a smaller PCD meshes with the sun gear 39. Needle roller bearings 44a and 44b are interposed between the pinion gears 41a and 41b and the pinion shafts 42a and 42b, respectively. Each pinion shaft 42a, 42b is provided with an oil supply hole 40.

  As shown in FIG. 1, the carrier 43 is disposed along the inner surface of the lid casing 14d, and between the carrier auxiliary member 46 disposed along the arm 33, the pinion shafts 42a and 42b. Support each end. Coupling protrusions 47 are provided at a plurality of locations on the outer peripheral edge of the carrier 43 toward the differential side carrier auxiliary member 46, and small protrusions 48 provided at the tips of the coupling protrusions 47 are coupled to the carrier auxiliary member 46. It is inserted and fixed in the hole 49. As a result, the carrier 43 and the carrier auxiliary member 46 are combined and integrated.

  The carrier 43 has a boss 50 protruding outward at its center. An axial bearing hole 51 is provided at the inner end of the boss 50 (the end on the differential portion 13 side), and the end of the first output shaft 15 is inserted into the bearing hole 51 as described above to form a needle shape. A first output shaft support bearing 52 formed of a roller bearing is rotatably supported.

  The second output shaft 16 is integrally provided at the center of the closed outer end of the boss 50. A carrier support bearing 54 constituted by a rolling bearing is interposed between the boss 50 and the boss 53 of the lid casing 14 d, and the carrier 43 and the second output shaft 16 are supported by the casing 14 by the carrier support bearing 54. An oil seal 55 is mounted between the bosses 50 and 53 outside the carrier support bearing 54 to seal the lubricating oil in the speed-reducing differential casing 14b.

  As described above, since the first output shaft support bearing 52 and the carrier support bearing 54 are disposed in the radial direction, the position of the second output shaft 16 approaches the first output shaft 15. Since the left and right wheels are attached to the distal ends of the first output shaft 15 and the second output shaft 16 via constant velocity joints, the mounting angle of the constant velocity joint is determined by the close proximity of the positions of the output shafts 15 and 16. There is an advantage of becoming smaller.

  As shown in FIGS. 1 and 4, thrust bearings 57, between the large gear 32 and the partition casing 14 c, between the large gear 32 and the sun gear 39, and between the sun gear 39 and the carrier 43, respectively. 58 and 59 are interposed.

  The electric vehicle deceleration differential apparatus of Embodiment 1 is configured as described above, and the operation thereof will be described next.

  Now, assuming that all the electric motors 11 (four in the illustrated example) are driven simultaneously, each motor shaft 22 rotates, and the small gear 31 rotates via the one-way clutch 30. At the same time, the large gear 32 meshed with the small gear 31 is decelerated and rotated, and the annular portion 34 of the differential portion 13 and the ring gear 38 integrated therewith are rotated via the arm 33.

  The load on one wheel of the vehicle is applied to the sun gear 39 of the differential section 13 via the first output shaft 15, and the load on the other wheel is applied to the carrier 43 via the second output shaft 16. When the loads acting on both wheels are equal, the sun gear 39, the pinion gears 41a and 41b, and the carrier 43 rotate together with the rotation of the ring gear 38 and do not rotate relative to each other.

  For this reason, the driving forces of the four electric motors 11 are equally distributed to the first output shaft 15 via the sun gear 39 and to the second output shaft 16 via the carrier 43, and the left and right wheels are rotated at a constant speed.

  On the other hand, if a difference occurs between the loads acting on the left and right wheels, the driving force is driven by the rotation and revolution of the pinion gears 41a and 41b, and the first output shaft 15 and the second output through the above path according to the load difference. Differentially distributed to the shaft 16.

That is, when the load acting on the first output shaft 15 becomes relatively large and the rotational speed Ns of the sun gear 39 integrated therewith is smaller than the input rotational speed Nr of the ring gear 38 by ΔN, the rotational speed of the carrier 43 is increased. Nc is
Nc = Nr + λ / (1-λ) · ΔN
Thus, the speed of the second output shaft 16 is increased. Where λ is the gear ratio (= Zs / Zr), Zs is the number of teeth of the sun gear 39, and Zr is the number of teeth of the ring gear 38.

On the contrary, when the load acting on the second output shaft 16 becomes relatively large and the rotation speed Nc of the carrier 43 integrated therewith is smaller than the input rotation speed Nr by ΔN, the rotation speed Ns of the sun gear 39 is ,
Ns = Nr + (1-λ) / λ · ΔN
Thus, the first output shaft 15 is accelerated.

  Note that the number of the electric motors 11 to be operated is appropriately determined in the control device according to the magnitude of the load. When there is a stopped electric motor 11, the one-way clutch 30 attached to the motor shaft 22 is turned off to prevent the motor shaft 22 from rotating from the large gear 32.

  Oil bath lubrication is performed as a lubrication method for the speed reduction unit 12 and the differential unit 13. That is, the lubricating oil is accumulated up to a certain level in the inner bottom portion of the deceleration differential casing 14b, and the arm 33 supporting the annular portion 34 in the deceleration portion 12 scoops up the lubricating oil during rotation. In the differential portion 13, the coupling protrusion 47, the pinion gears 41a and 41b, and the like provided on the outer peripheral portion of the carrier 43 perform a scraping action of the lubricating oil. The scraped lubricating oil is scattered inside the speed reduction unit 12 and the differential unit 13 and applied to each component.

  The lubricating oil moves in the axial direction in the oil passage hole 56 of the sun gear 39 between the arms 33 extending in the radial direction from the large gear 32.

  In the first embodiment described above, the differential unit 13 is a planetary gear mechanism. However, the differential unit 13 may be a bevel gear type composed of a differential case, a pinion gear, and a side gear.

DESCRIPTION OF SYMBOLS 11 Electric motor 12 Deceleration part 13 Differential part 14 Casing 14a Motor casing 14b Deceleration differential casing 14c Bulkhead casing 14d Lid casing 15 1st output shaft 16 2nd output shaft 17 Boss 18 1st output shaft support bearing 19 Oil seal 21 Motor Case 22 Motor shaft 22a Small diameter portion 23 Rolling bearing 24 Rolling bearing 25 Oil seal 26 Rotor 27 Stator 28 Oil seal 29 Rolling bearing 30 One-way clutch 31 Small gear 32 Large gear 33 Arm 34 Annular portion 38 Ring gear 39 Sun gear 40 Oiling hole 41a, 41b Pinion gear 42a, 42b Pinion shaft 43 Carrier 44a, 44b Needle roller bearing 45 Serration hole 46 Carrier auxiliary member 47 Coupling projection 48 Small projection 9 coupling hole 50 boss 51 bearing hole 52 first output shaft support bearing 53 boss 54 carrier support bearing 55 oil seal 56 Tsuyuana 57, 58, 59 Thrust bearing

Claims (11)

  It consists of a combination of an electric motor, a decelerating unit and a differential unit, a casing containing the respective members, and first and second output shafts, and the driving force of the electric motor is decelerated at the decelerating unit and output to the differential unit The decelerated driving force is output to the two distribution members according to the magnitude of the load in the differential device, one distribution member is connected to the first output shaft, and the other distribution member is the second output. In the reduction differential for an electric vehicle connected to a shaft, a plurality of the electric motors are arranged around the first output shaft, and the reduction gear is supported by the motor shaft of the electric motor; A large gear meshed with the small gear rotatably supported by a shaft, and a part of the large gear is connected to an input gear of the differential unit. Electric vehicle deceleration differential.   2. The electric according to claim 1, wherein a one-way clutch is interposed between the motor shaft and the small gear to transmit a driving force from the motor shaft but cut off a driving force from the small gear. Deceleration differential for automobiles.   The electric vehicle deceleration differential apparatus according to claim 2, wherein each of the electric motors can be operated independently.   The electric vehicle deceleration differential apparatus according to any one of claims 1 to 3, wherein the electric motor is a general-purpose motor.   The large gear of the speed reduction part is an external tooth type, and is rotatably supported on the outer diameter surface of the first output shaft via a rolling bearing. Reducer differential for electric vehicles.   5. The electric vehicle reduction gear according to claim 1, wherein the large gear of the speed reduction portion is an internal tooth type, and is rotatably supported on an inner diameter surface of the casing via a rolling bearing. Differential device.   The differential portion is constituted by a planetary gear mechanism, the input gear to which the reduced driving force from the reduction portion is input is a ring gear of the planetary gear mechanism, the one distribution member is a sun gear, and the first gear 7. A reduction differential for an electric vehicle according to claim 1, wherein the other distribution member is a carrier connected to an output shaft, and the carrier is connected to the second output shaft. apparatus.   The reduction differential apparatus for an electric vehicle according to claim 7, wherein the second output shaft is integrally provided at one end of the boss of the carrier.   The boss is provided with an axial bearing hole, and a first output shaft support bearing is interposed between one end of the first output shaft inserted into the bearing hole and the inner surface of the bearing hole. An electric vehicle deceleration differential apparatus according to any one of claims 1 to 8.   10. The electric vehicle deceleration differential apparatus according to claim 1, wherein a carrier support bearing is interposed between an outer diameter surface of the boss and the casing.   11. The electric vehicle differential reduction apparatus according to claim 1, wherein the lubrication of the speed reduction part and the differential part is oil bath lubrication.

Images