JP2018009584A - Vehicle drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize a vehicle by restraining the center of gravity height of a vehicle drive device, which increases the weight by incorporating a torque difference amplifier 30, to be low while preferably supplying tube oil into a planet gear Pof the torque difference amplifier 30.SOLUTION: Intermediate gear shafts 13L and 13R of reduction gears 3L and 3R incorporating the torque difference amplifier 30 are disposed at the lowest position from the ground surface among gear shafts constituting the reduction gears 3L and 3R so as to restrain the center of gravity height of the vehicle drive device to be low; and the oil level of lube oil included in a reduction gear housing 9 is set at a height in which a planet gear of the torque difference amplifier 30 located at lowest point immerses in a vehicle stopping state.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a vehicle drive device capable of amplifying a torque difference and transmitting drive torque from two independent drive sources to left and right drive wheels.

  In a vehicle such as an electric vehicle, an electric motor is disposed on each of the left and right drive wheels, and the turning moment of the vehicle is controlled by giving an appropriate drive torque difference to the left and right wheels by controlling each electric motor independently. It is known. When it is effective to generate a large difference in driving torque between the left and right drive wheels in order to achieve smooth turning of the vehicle and to suppress changes in vehicle behavior such as extreme understeer and extreme oversteer There is. For this reason, it is desirable to amplify the difference between the torques output from the two electric motors and transmit them to the left and right drive wheels.

  In Patent Document 1 and Patent Document 2, a vehicle drive provided with a torque difference amplifying device in which two planetary gear mechanisms with three elements and two degrees of freedom are coaxially arranged between two drive sources and left and right drive wheels. An apparatus is disclosed.

  The vehicle drive device disclosed in FIG. 5A of Patent Document 1 (hereinafter referred to as Conventional Technology 1) has a configuration as shown in the skeleton diagram shown in FIG.

  The vehicle drive device 100 includes left and right electric motors 102L and 102R mounted on the vehicle, and gears constituting a gear train of left and right reduction gears provided between the electric motors 102L and 102R and the left and right drive wheels 104L and 104R. 106L, 106R, 107L, 107R, and the torque difference amplifying device 105 is incorporated between the gears 106L, 106R, 107L, 107R constituting the gear train of the left and right reduction gears.

  The electric motors 102L and 102R operate by electric power from a battery (not shown) mounted on the vehicle, are individually controlled by an electronic control device (not shown), and can generate and output different torques.

  The output shafts 102aL and 102aR of the electric motors 102L and 102R are connected to the coupling members 111 and 112 of the torque difference amplifying device 105 via gears 106L and 106R of the gear train of the reduction gear, respectively. The output from the torque difference amplifying device 105 is given to the left and right drive wheels 104L, 104R via gears 107L, 107R of the gear train of the speed reducer.

  The torque difference amplifying device 105 is configured by combining two identical planetary gear mechanisms 110L and 110R having three elements and two degrees of freedom on the same axis.

As the planetary gear mechanisms 110L and 110R, for example, single-pinion type planetary gear mechanisms are employed. The single-pinion type planetary gear mechanism includes a sun gear S _L , S _R and internal gears R _L , R _R provided on the same axis, and these sun gears S _L , S _R and internal gears R _L , R _R. A plurality of planetary gears P _L and P _R and planetary gears P _L and P _R are rotatably supported, and are provided coaxially with the sun gears S _L and S _R and the internal gears R _L and R _R. was planet carrier C _L, is composed of a C _R, the planetary gear P _L, P _R is engaged the sun gear S _L, S _R and the internal gear R _L, in the R _R. Here, the sun gear S _L, S _R and the planetary gears P _L, P _R is the external gear having gear teeth on the outer circumference, the internal gear R _L, R _R is the internal gear having gear teeth on the inner peripheral is there.

As shown in FIG. 14, the torque difference amplifying device 105 includes a first planetary gear mechanism 110L having a sun gear S _L , a planet carrier C _L , a planet gear P _L and an internal gear R _L , as well as the sun gear S _R , planet carrier C _R, constitutes a combination of the second planetary gear mechanism 110R having a planetary gear P _R and the internal gear R _R coaxially.

Then, the sun gear S _L of the first planetary gear mechanism 110L and the internal gear R _R of the second planetary gear mechanism 110R is coupled by a first coupling member 111, and the internal gear R _L of the first planetary gear mechanism 110L second The sun gear S _R of the planetary gear mechanism 110R is coupled by the second coupling member 112.

Torque TM1 generated by the electric motor 102L is input to the first coupling member 111 via the gear 106L, and torque TM2 generated by the electric motor 102R is input to the second coupling member 112 via the gear 106R. Is done. Further, the planet carrier C _R of the planetary carrier C _L and the second planetary gear mechanism 110R of the first planetary gear mechanism 110L, respectively gears 107L, through 107R left and right drive wheels 104L, the output is connected to the 104R is taken out .

  Next, the vehicle drive device disclosed in Patent Document 2 (hereinafter referred to as Conventional Technology 2) has a configuration as shown in the skeleton diagram shown in FIG.

  In FIG. 15, in order to make the difference from the prior art 1 easier to understand, the electric motors 102L and 102R are arranged on the left and right sides so as to be the same as in the prior art 1, and the same components are denoted by the same reference numerals. ing.

  As shown in FIG. 15, the vehicle drive device 100 is provided between a first electric motor 102L and a second electric motor 102R mounted on the vehicle, a left drive wheel 104L and a right drive wheel 104R, and these. A torque difference amplifying device 105 and gears 106L and 106R are provided.

The first electric motor 102L and the second electric motor 102R operate with electric power from a battery (not shown) mounted on the vehicle, and are individually controlled by an electronic control device (not shown) to generate different torques. Can be output. The output shaft 102aL of the first electric motor 102L and the output shaft 102aR of the second electric motor 102R are connected to the sun gears S _L and S _R of the torque difference amplifying device 105 via gears 106L and 106R, respectively. The output from the torque difference amplifying device 105 is given to the left and right drive wheels 104L, 104R.

  Like the prior art 1, the torque difference amplifying apparatus 105 of the prior art 2 is configured by combining two identical planetary gear mechanisms 110L and 110R having three elements and two degrees of freedom on the same axis. As the planetary gear mechanisms 110L and 110R, for example, single-pinion type planetary gear mechanisms are employed.

Then, the planet carrier C _L of the first planetary gear mechanism 110L and the internal gear R _R of the second planetary gear mechanism 110R is coupled by a first coupling member 111, the internal gear R _L of the first planetary gear mechanism 110L When the planet carrier C _R of the second planetary gear mechanism 110R is coupled by the second coupling member 112.

The first electric motor torque TM1 generated in 102L is input to the sun gear S _L of the first planetary gear mechanism 110L via a gear 106L of the reduction gear train, the torque TM2 generated by the second electric motor 102R is input to the sun gear S _R of the second planetary gear mechanism 110R via the gears 106R of the reduction gear train.

  The first coupling member 111 and the second coupling member 112 are connected to the left and right drive wheels 104L and 104R, respectively, and output is taken out.

  As described above, in the techniques described in the related art 1 and the related art 2, when the torques TM1 and TM2 different from each other are generated by the two electric motors 102L and 102R to give the input torque difference ΔTIN, the torque difference amplifying device 105 The input torque difference ΔTIN is amplified, and a driving torque difference ΔTOUT larger than the input torque difference ΔTIN can be obtained.

JP 2015-21594 A Japanese Patent No. 4907390

  Incidentally, the torque difference amplifying device 105 that connects the two planetary gear mechanisms may be arranged so that the connecting portion is coaxially arranged or covers the carrier, depending on the connecting method. The torque difference amplifying device 105 only engages at the same position as long as no torque difference occurs. However, since the inside rotates at the time of torque difference or corner driving, if the lubrication is insufficient, the life of the meshing surface is reduced. To do. Also, if the planetary gear mechanism is going to operate at the start of starting after a long stop, for example, the support bearing inside the planetary gear may be in a dry state, and in the worst case due to metal contact, the planetary gear There is concern about early peeling of parts.

  The torque difference amplifying device 105 does not have a reduction function in itself, and is incorporated in a gear shaft of a gear train constituting a normal reduction device. Therefore, when the torque difference amplifying device 105 is added to the gear train of the speed reducer, the weight is increased purely. Since it is necessary to receive the power of the vehicle drive device and transmit the amplified torque, an increase in weight by the torque difference amplifying device 105 is unavoidable in order to obtain a required strength.

  Even if the gears of the gear train of the reduction gear and the torque difference amplifying device 105 are partially integrated, an increase in weight is inevitable.

  And if the height of the center of gravity of the vehicle drive device that has increased in weight increases due to the incorporation of the torque difference amplification device, the stability of the vehicle will deteriorate, so even if the torque difference amplification device is incorporated, the vehicle drive without the torque difference amplification device I want to avoid having a higher center of gravity than equipment.

  Therefore, the present invention can satisfactorily supply the lubricating oil into the planetary gear mechanism constituting the torque difference amplifying device, and further, the center of gravity of the vehicle drive device whose weight is increased by incorporating the torque difference amplifying device. An object of the present invention is to improve vehicle stability by keeping the height low.

  In order to solve the above-described problems, the present invention has an input gear connected to the two drive sources between two drive sources mounted on the vehicle and independently controllable and the left and right drive wheels. An input gear shaft, an output gear shaft connected to the left and right drive wheels and having an output gear, and at least one intermediate gear shaft that transmits power between the input gear shaft and the output gear shaft by meshing of the gears A combination of two planetary gear mechanisms coaxially with one intermediate gear shaft of the reduction device, and a specific element of one planetary gear mechanism and a specific element of the other planetary gear mechanism An intermediate gear of a speed reducer incorporating the torque difference amplifying device in a vehicle drive device incorporating a torque difference amplifying device coupled to the left and right drive wheels to amplify and transmit the torque difference to the left and right drive wheels Shaft, reducer It is characterized in that it is arranged at the lowest position from the ground among the respective gear shafts constituting it.

  A part of the planetary gear located at the lowest point of the planetary gear mechanism that constitutes the torque difference amplifying device when the oil level of the lubricating oil sealed in the speed reducer housing that houses the speed reducer is stopped is ensured. By setting the immersion height, the internal lubrication of the planetary gear mechanism can be effectively performed.

  Also, lubrication oil can flow between the left and right sides of the torque difference amplifying device by providing a lubricating oil supply hole penetrating left and right in the center of the intermediate gear shaft of the reduction gear incorporating the torque difference amplifying device. can do.

  By providing a radial oil supply passage in the axial oil supply hole, lubricating oil can be supplied to the components on the outer peripheral side of the planetary gear mechanism.

  A lubricating oil introduction cylinder that guides the lubricating oil sealed in a reduction gear housing that houses the reduction gear to the oil supply hole can be attached to an end portion on the outboard side of the axial oil supply hole.

  The lubricating oil introduction cylinder is formed by a cylindrical portion and a conical cylindrical portion that is narrowed from the end on the inboard side of the cylindrical portion toward the outer end surface of the oiling hole, thereby supplying external lubricating oil to the lubricating oil. Can preferentially flow into the hole.

  An engagement claw protruding to the outer peripheral side is provided in the cylindrical portion of the lubricating oil introduction cylinder, and the engagement groove engaged with the engagement claw is a hollow shaft of an intermediate gear shaft of a reduction gear incorporating a torque difference amplifying device. You may make it provide in the internal peripheral surface of a part.

  By providing a missing tooth on a part of the spline teeth that connect the intermediate gear shaft and the connecting shaft of the torque difference amplifying device, the flow of lubricating oil from the outer surface of the torque difference amplifying device to the inside can be improved. it can.

  As described above, according to the present invention, the intermediate gear shaft incorporating the torque difference amplifying device is disposed at a position where the ground height is the lowest in the speed reducer housing constituting the speed reducer than the other gear shafts. Therefore, the height of the center of gravity of the vehicle drive device that has increased in weight by incorporating the torque difference amplifying device can be kept low, so that the stability of the vehicle can be achieved and the torque difference amplifying device can be lubricated inside the planetary gear. Oil can be supplied satisfactorily.

It is a cross-sectional top view which shows embodiment of the vehicle drive device of this invention. It is an enlarged view of the torque difference amplifying device portion of the embodiment of FIG. It is sectional drawing of the AA line of FIG. FIG. 4 is a cross-sectional view showing a relationship with the ground by rotating FIG. 3 by 90 degrees. It is sectional drawing which shows the oil quantity of the lubricating oil enclosed in the reduction gear housing. It is sectional drawing which shows other embodiment of the torque difference amplifier part. It is sectional drawing which shows other embodiment of the torque difference amplifier part. It is an expanded sectional view of a lubricating oil introduction cylinder. It is sectional drawing which shows other embodiment of the torque difference amplifier part. (A) is an expanded sectional view of the lubricating oil introduction cylinder used in the embodiment of FIG. 9, and (b) is a side view seen from the end face side of the conical cylinder portion of the lubricating oil introduction cylinder. It is sectional drawing of the BB line of FIG. It is explanatory drawing of the electric vehicle which showed the torque difference amplifier of the vehicle drive device which concerns on embodiment of FIG. 1 with the skeleton figure. It is a speed diagram for demonstrating the torque difference amplification factor by the torque difference amplification apparatus incorporated in the vehicle drive device which concerns on embodiment of FIG. It is a skeleton figure which shows the torque difference amplifier of the vehicle drive device which concerns on the prior art 1. FIG. It is a skeleton figure which shows the torque difference amplifier of the vehicle drive device which concerns on the prior art 2. FIG.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  An electric vehicle AM shown in FIG. 12 is a rear wheel drive system, and includes a chassis 60, drive wheels 61L and 61R as rear wheels, front wheels 62L and 62R, and a two-motor vehicle drive device 1 according to the present invention. A battery 63, an inverter 64, and the like are provided. In FIG. 12, the gear structure of the vehicle drive device 1 is shown with the skeleton figure.

  A vehicle drive device 1 shown in FIG. 1 includes two electric motors 2L and 2R that are mounted on a vehicle and can be controlled independently, and left and right drive wheels 61L and 61R and two electric motors 2L and 2R. 2 left and right reduction gears 3L and 3R provided between them.

  The drive torque of the two-motor type vehicle drive device 1 is transmitted to the left and right drive wheels 61L and 61R via a drive shaft composed of constant velocity joints 65a and 65b and an intermediate shaft 65c (FIG. 12).

  As a mounting form of the two-motor type vehicle drive device 1, a front wheel drive system or a four wheel drive system may be used in addition to the rear wheel drive system shown in FIG. In the four-wheel drive system, the vehicle drive device 1 shown in FIG. 1 may be mounted on either the front wheel or the rear wheel, or may be mounted on one of them, and the other may be another drive means such as an engine. There may be.

  The left and right electric motors 2L and 2R in the two-motor type vehicle drive device 1 use electric motors having the same maximum output and the same output characteristics. As shown in FIG. Contained.

  The motor housings 4L and 4R include cylindrical motor housing bodies 4aL and 4aR, outer walls 4bL and 4bR that close the outer surfaces of the motor housing bodies 4aL and 4aR, and reduction gears on the inner surfaces of the motor housing bodies 4aL and 4aR. It consists of inner walls 4cL and 4cR separated from 3L and 3R. The inner walls 4cL and 4cR are provided with openings through which the motor shaft 5a is drawn.

  As shown in FIG. 1, the electric motors 2 </ b> L and 2 </ b> R are of a radial gap type in which a stator 6 is provided on the inner peripheral surface of the motor housing main body 4 aL and 4 aR, and a rotor 5 is provided with a gap in the inner periphery of the stator 6. I am using something. The electric motors 2L and 2R may be axial gap types.

  The rotor 5 has a motor shaft 5a in the center, and the motor shaft 5a is drawn from the openings of the inner walls 4cL and 4cR of the motor housing main bodies 4aL and 4aR to the reduction gears 3L and 3R, respectively. A seal member 7 is provided between the periphery of the inner side walls 4cL and 4cR of the motor housing bodies 4aL and 4aR and the motor shaft 5a.

  The motor shaft 5a is rotatably supported by the rolling bearings 8a and 8b on the inner walls 4cL and 4cR and the outer walls 4bL and 4bR of the motor housing bodies 4aL and 4aR. In FIG. 1, the rolling bearings 8a and 8b are the same, but those of different sizes may be combined.

  A reduction gear housing 9 that accommodates two reduction gears 3L and 3R provided in parallel on the left and right is divided into three pieces in a direction perpendicular to the gear shafts of the reduction gears 3L and 3R, as shown in FIG. The housing 9a has a three-piece structure including left and right side housings 9bL and 9bR fixed to both side surfaces of the central housing 9a. The left and right side housings 9bL and 9bR are fixed to the openings on both sides of the central housing 9a by a plurality of bolts (not shown).

  A plurality of bolts 10 are used to fix side faces 9bL and 9bR of the reduction gear housing 9 on the side of the outboard side (outside the vehicle body) and the inner side walls 4cL and 4cR of the motor housing bodies 4aL and 4aR of the electric motors 2L and 2R Thus, the two electric motors 2L and 2R are fixedly arranged on the left and right sides of the reduction gear housing 9 (FIG. 1).

  As shown in FIG. 1, the central housing 9a is provided with a partition wall 11 at the center. The speed reducer housing 9 is divided into left and right parts by the partition wall 11, and independent left and right accommodation chambers for accommodating the two speed reducers 3L and 3R are provided in parallel.

  As shown in FIG. 1, the reduction gears 3L and 3R are provided symmetrically, and input gear shafts 12L and 12R having an input gear 12a to which power is transmitted from the motor shaft 5a, and the input gear 12a are large. Intermediate gear shafts 13L and 13R having both an output-side small gear 13b meshing with the input-side external gear 13a and the output gear 14a, and an output gear 14a. The constant-velocity joint 65a is pulled out from the speed reducer housing 9; 65 is a parallel shaft gear reducer including output gear shafts 14L and 14R that transmit torque to the drive wheels 61L and 61R via an intermediate shaft 65c (see FIG. 11). The input gear shafts 12L and 12R, the intermediate gear shafts 13L and 13R, and the output gear shafts 14L and 14R of the left and right reduction gears 3L and 3R are coaxially arranged.

  Both ends of the input gear shafts 12L and 12R of the reduction gears 3L and 3R are respectively connected to bearing fitting holes 16a formed on both left and right sides of the partition wall 11 of the central housing 9a and bearing fitting holes 16b formed on the side housings 9bL and 9bR. It is rotatably supported via rolling bearings 17a and 17b.

  The end portions on the outboard side of the input gear shafts 12L, 12R are drawn outward from the openings provided in the side housings 9bL, 9bR, and between the openings and the outer ends of the input gear shafts 12L, 12R. Is provided with an oil seal 18 to prevent leakage of the lubricating oil sealed in the speed reducer housing 9.

  The input gear shafts 12L and 12R have a hollow structure, and end portions of the motor shaft 5a are inserted into the hollow input gear shafts 12L and 12R. The input gear shafts 12L, 12R and the motor shaft 5a are coupled by splines (including serrations, the same applies hereinafter).

  At least one or more intermediate gear shafts 13L and 13R are arranged. In the embodiment shown in FIG. 1, the intermediate gear shafts 13L and 13R have a pair of intermediate gear shafts 13L and 13R.

  The intermediate gear shafts 13L and 13R constitute a stepped gear shaft having an input side external gear 13a meshing with the input gear 12a on the outer peripheral surface thereof and an output side small diameter gear 13b meshing with the output gear 14a. At both ends of the intermediate gear shafts 13L and 13R, rolling bearings 20a and 20b are fitted into bearing fitting holes 19a formed on both surfaces of the partition wall 11 of the central housing 9a and bearing fitting holes 19b formed on the side housings 9bL and 9bR. Is supported through. And the partition wall 11 of the center housing 9a which provides the bearing fitting hole 19a has penetrated so that the 1st coupling member 31 and the 2nd coupling member 32 which are mentioned later may pass. In FIG. 1, the rolling bearings 20a and 20b have different sizes, but they may be combined with each other.

  The intermediate gear shafts 13L and 13R arranged on the same axis are connected to the intermediate gear shafts 13L and 13R so that the drive torque applied from the two electric motors 2L and 2R is a torque difference between the left and right drive wheels 61L and 61R. The torque difference amplifying device 30 for amplifying and distributing the signal is incorporated.

  The torque difference amplifying device 30 includes three-element and two-degree-of-freedom planetary gear mechanisms 30L and 30R that are coaxially combined with a pair of left and right intermediate gear shafts 13L and 13R arranged coaxially.

The planetary gear mechanism constitute a torque difference amplifier 30 30L, 30R, the intermediate gear shaft 13L, internal gear incorporated to the input-side external gear 13a of the large diameter 13R R _L, and R _R, the internal gear R _L, R _R and the sun gear S _L provided coaxially, S _R and internal gear R _L, R _R and the sun gear S _L, a plurality of planetary gears which are arranged equally circumferentially revolving gear meshing with S _R P _L and P _R and planetary gears P _L and P _R are rotatably supported, and planetary carriers C _L and C _R provided coaxially with the internal gears R _L and R _R and one planet carrier C _A first coupling member 31 that couples _L (left side of the figure in FIG. 1) and the other sun gear S _R (right side of the figure in FIG. 1), and one sun gear S _L (left side of the figure in FIG. 1); a second coupling member 32 for coupling the other of the planet carrier C _R (right side in FIG. in FIG. 1), the internal gear R _L, is connected to R _R Further, the output side small diameters of the intermediate gear shafts 13L, 13R that mesh with the input side external gear 13a of the intermediate gear shafts 13L, 13R that mesh with the input gear 12a of the input gear shafts 12L, 12R and the output gear 14a of the output gear shafts 14L, 14R. And the output side small-diameter gear 13b of the intermediate gear shafts 13L and 13R is connected to the planetary carriers C _L and C _R.

When a plurality of pairs of intermediate gear shafts 13L and 13R are provided, the planetary gear mechanisms 30L and 30R constituting the torque difference amplifying device 30 are incorporated only into any one of the pair of intermediate gear shafts 13L and 13R. The input-side external gear 13a connected to the internal gears R _L , R _R is an output-side small gear 13b provided on the drive-side intermediate gear shafts 13L, 13R among the plural pairs of intermediate gear shafts 13L, 13R, or An output-side small-diameter gear 13b that is disposed so as to mesh with the input gear 12a of the input gear shafts 12L and 12R and is provided coaxially with the planetary gear mechanisms 30L and 30R includes a plurality of pairs of intermediate gear shafts 13L and 13R. Are arranged so as to mesh with the input side external gear 13a provided on the driven intermediate gear shafts 13L, 13R or the output gear 14a of the output gear shafts 14L, 14R.

As shown in FIG. 2, the planetary carriers C _L and C _R are composed of a carrier pin 33 that supports the planetary gears P _L and P _R , and an outboard side carrier flange that is connected to the outboard side end of the carrier pin 33. 34a and an inboard carrier flange 34b connected to the inboard side end.

  The carrier flange 34a on the outboard side includes a hollow shaft portion 35 extending toward the outboard side, and the end portion on the outboard side of the hollow shaft portion 35 is formed on the side housings 9bL and 9bR of the speed reducer housing 9. It is supported by the fitting hole 19b via the rolling bearing 20b (refer FIG. 1).

  The carrier flange 34b on the inboard side includes a hollow shaft portion 36 extending toward the inboard side, and an end portion on the inboard side of the hollow shaft portion 36 is formed in a bearing fitting hole formed in the partition wall 11 of the central housing 9a. 19a is supported via a rolling bearing 20a.

  In the embodiment shown in FIG. 1, the output-side small-diameter gear 13b is integrally formed on the outer peripheral surface of the hollow shaft portion 35 of the carrier flange 34a.

The planetary gears P _L and P _R are supported by the carrier pin 33 via the needle roller bearing 37.

Here, each of the carrier flanges 34a, 34b facing surface and a planetary gear P _L of, inserting the thrust plate (not shown) between the P _R, the planetary gear P _L, even working to smooth rotation of the P _R Good.

Wherein each carrier flange 34a, 34b outer peripheral surface and the inner gear R _L of the, between the R _R, are arranged rolling bearing 39.

  As shown in FIG. 2, a collar 40 is arranged between the inboard carrier flange 34b and the rolling bearing 20a that supports the hollow shaft portion 36 of the inboard carrier flange 34b.

  The first coupling member 31 and the second coupling member 32 that couple the two planetary gear mechanisms 30L and 30R that constitute the torque difference amplifying device 30 of the vehicle drive device 1 have the central housing 9a of the reduction gear housing 9 left and right. The partition wall 11 is partitioned and incorporated.

  The first coupling member 31 and the second coupling member 32 are arranged on the same axis, and one coupling member (second coupling member 32 in FIG. 1) is a hollow shaft, and the other coupling member (first coupling member in FIG. 1). The coupling member 31) has a double structure consisting of a shaft inserted through the hollow shaft.

As shown in FIG. 2, the end portion of the right side of the planetary gear mechanism 30R side in the second coupling member 32 consists of a hollow shaft, the hollow shaft portion 36 of the carrier flange 34b on the inboard side of the planet carrier C _R the spline 41 is provided, it is connected by spline fitting to the second coupling member 32 the planet carrier C _R.

Further, the end portion of the left planetary gear mechanism 30L side of the first coupling member 31, a spline 42 provided on the hollow shaft portion 35 of the carrier flange 34a on the outboard side of the planet carrier C _L, first coupling member 31 Are connected to the planet carrier C _L by spline fitting.

As described above, the two planetary gear mechanisms 30L, first coupling member 31 of the 30R and a second binding member 32, by connecting the splined to the planet carrier C _L and the planet carrier C _R, two The planetary gear mechanism can be divided into left and right, and can be incorporated into the three-piece reduction gear housing 9 from the left and right in the same manner as other reduction gear shafts.

End of the planet carrier C _L of the second coupling member 32 has, on its outer peripheral surface, the external gear meshing with the planetary gears P _L of the left planetary gear mechanism is formed, the sun the external gear of the left planetary gear mechanism A gear S _L is configured.

The first coupling member 31 inserted through the second coupling member 32 constituted by a hollow shaft has a large diameter portion 43 at an end portion on the right planetary gear mechanism 30R side, and an outer peripheral surface of the large diameter portion 43 is provided. , external gear meshing with the planetary gears P _R of the right planetary gear mechanism 30R is formed, the outer gear constitutes the sun gear S _R of the right planetary gear mechanism 30R.

Of the first coupling member 31 and second coupling member 32, the maximum diameter of the sun gear S _R are connected to the inner diameter side of the coupling member (first coupling member 31), the binding of the outer diameter side member (the second coupling by member 32) is set smaller than the minimum diameter of the spline hole of the inner surface of the hollow shaft portion 36 of the carrier flange 34b on the inboard side of the planet carrier C _R for mating, the inner diameter side of the coupling member (first coupling member 31 ) Can be easily incorporated.

  Between the outer peripheral surface of the inner diameter side coupling member (first coupling member 31) and the inner peripheral surface of the outer diameter side coupling member (second coupling member 32), there are needles 44 at both ends of the collar 44. The roller bearings 45 and 46 are interposed.

The first coupling member 31 and the second coupling member 32 and the planetary carriers C _L and C _R are fitted (splines 42 and 41) with a fitting tolerance that can be slid in the axial direction. large diameter of the input-side external gear 13a meshing, the output gear 14a and the output-side small-diameter external gear 13b meshing with this sun gear S _L, S _R and the planetary gears P _L, P _R and the internal gear R _L, the R _R There is a helical gear for at least one meshing, and even if an axial load is generated, it is possible to prevent an uneven load on the gear tooth surface.

Further, the load due to the axial movement due to the sliding movement of the spline (splines 42, 41) between the first coupling member 31 and the second coupling member 32 and the planetary carriers C _L , C _R is the outer diameter side coupling member ( In each embodiment, thrust bearings 47 and 48 are provided and supported at both ends of the second coupling member 32).

The coupling member (the first coupling member 31 in the embodiment of FIG. 1) on the inner diameter side of the double-structure shaft that couples the two planetary gear mechanisms 30L and 30R is the coupling member (the first coupling member in the embodiment of FIG. 1). 31) and the planet carrier (C _{L in the} embodiment of FIG. 1) on the side opposite to the spline fitting, the deep planetary bearing (C _{R in the} embodiment of FIG. 1) is connected by a deep groove ball bearing 49 to the other planet carrier. I support it.

  By the way, the intermediate gear shafts 13L and 13R incorporating the torque difference amplifying device 30 are reduced more than the other gear shafts constituting the reduction gears 3L and 3R, that is, the input gear shafts 12L and 12R and the output gear shafts 14L and 14R. The housing 9 is disposed at a position where the ground height is lowest (see FIGS. 4 and 5). 4 and 5, the symbol G indicates the ground.

  For example, if the gear shafts constituting the reduction gears 3L and 3R are a three-axis structure, the intermediate gear shafts 13L and 13R incorporating the torque difference amplifying device 30 are arranged on the second axis, and if the gear shaft is a four-axis structure, 2 It arrange | positions to the axis | shaft or the 3rd axis | shaft, and arrange | positions so that the axis | shaft which has arrange | positioned the intermediate gear shafts 13L and 13R incorporating the torque difference amplifier 30 may become the lowest position from the ground G.

  Thus, by arranging the heavy intermediate gear shafts 13L and 13R incorporating the torque difference amplifying device 30 at the lowest position from the ground G, the vehicle driving device 1 can be lowered in the center of gravity.

Further, by arranging the intermediate gear shafts 13L and 13R incorporating the torque difference amplifying device 30 at a position lower than the other gear shafts from the ground, as shown in FIG. 5, the planetary gear constituting the torque difference amplifying device 30 is provided. The planetary gears P _L and P _{R of the} mechanisms 30L and 30R can be brought closest to the oil level F of the lubricating oil sealed in the reduction gear housing 9.

Then, the oil level F of the lubricating oil enclosed inside the reduction gear housing 9, as shown in FIG. 5, the planetary gear mechanism 30L, the planetary gear P _L of 30R, a part of the P _R can be reliably immersed when the vehicle is stopped by setting the height, the planetary gears P _L, the internal lubrication of P _R performed effectively.

  Also, the coupling member (the first coupling member 31 in the embodiment of FIG. 1) on the inner diameter side of the double-structure shaft that couples the two planetary gear mechanisms 30L and 30R is lubricated between the left and right sides of the torque difference amplifying device 30. An oil supply hole 50 is provided in the shaft center so that oil can flow.

Furthermore, in the embodiment shown in FIG. 6, the outer diameter side coupling member (the second coupling member 32 in the embodiment of FIG. 1) is inserted into the oil supply hole 50 of the inner diameter side coupling member (the first coupling member 31 in the embodiment of FIG. 1). the position of the thrust bearing 47, 48 at both ends of) the provided radial oil supply passage 51, the sun gear S _L, the tooth surfaces of the S _R, the planetary gear P _L, the tooth surface or the like of the P _R, the torque difference amplifier Lubricating oil is supplied to the components on the outer peripheral side of the first coupling member 31 of the device 30.

  In the embodiment shown in FIG. 7, the oil supply hole 50 of the coupling member (the first coupling member 31 in the embodiment of FIG. 1) on the inner diameter side from the outer surface of the intermediate gear shafts 13 </ b> L and 13 </ b> R incorporating the torque difference amplifying device 30. In order to facilitate the introduction of the lubricating oil, a lubricating oil introducing cylinder 70 having a shape narrowed toward the outer end surface of the oil supply hole 50 is attached to the inner peripheral surface of the hollow shaft portion 35 of the carrier flange 34a. The external lubricating oil flows preferentially into the oil supply hole 50.

  The lubricating oil introduction cylinder 70 is narrowed toward the outer end surface of the oil supply hole 50 from the cylindrical portion 70a fitted on the inner peripheral surface of the hollow shaft portion 35 of the carrier flange 34a and the end portion on the inboard side of the cylindrical portion 70a. It consists of a conical cylinder part 70b.

  In the embodiment shown in FIG. 9, the engaging claw 70c protruding to the outer peripheral side is provided in the cylindrical portion 70a of the lubricating oil introducing cylinder 70, and the engaging groove 70d with which the engaging claw 70c engages is provided with the carrier flange. It is formed on the inner peripheral surface of the hollow shaft portion 35 of 34a.

  In the conical cylinder portion 70b of the lubricating oil introducing cylinder 70 of the embodiment shown in FIG. 9, a part of the lubricating oil introduced into the lubricating oil introducing cylinder 70 can be supplied to the outer surface side of the conical cylinder section 70b. A notch hole 70e is provided.

Moreover, the spline 42 for coupling the end portion of the left planetary gear mechanism 30L side of the first coupling member 31, and a hollow shaft portion 35 of the carrier flange 34a on the outboard side of the planet carrier C _L, as shown in FIG. 11 In addition, a missing tooth 71 may be provided to improve the flow of lubricating oil from the outer surface of the intermediate gear shafts 13L and 13R incorporating the torque difference amplifying device 30 into the torque difference amplifying device 30.

  Next, the output gear shafts 14L and 14R have a large-diameter output gear 14a, and bearing fitting holes 53a formed on both surfaces of the partition wall 11 of the central housing 9a and bearing fittings formed on the side housings 9bL and 9bR. The hole 53b is supported by rolling bearings 54a and 54b. The bearing fitting holes 53a and 53b have a stepped shape having a wall portion with which the outer rings of the rolling bearings 54a and 54b come into contact. In FIG. 1, the rolling bearings 54a and 54b are the same, but they may be combined in different sizes.

  Outboard side ends of the output gear shafts 14L and 14R are drawn out of the reduction gear housing 9 from openings formed in the side housings 9bL and 9bR, and are pulled out to the outboard side of the output gear shafts 14L and 14R. The outer joint portion of the constant velocity joint 65a is splined to the outer peripheral surface of the end portion.

  The constant velocity joint 65a coupled to the output gear shafts 14L and 14R is connected to the drive wheels 61L and 61R via the intermediate shaft 65c and the constant velocity joint 65b (see FIG. 11).

  An oil seal 55 is provided between the end of the output gear shafts 14L and 14R on the outboard side and the opening formed in the side housings 9bL and 9bR, and leakage of the lubricating oil sealed in the speed reducer housing 9 and the outside Intrusion of muddy water from

  The gear configuration of the two-motor type vehicle drive device 1 of the embodiment shown in FIG. 1 is as shown in the skeleton diagram shown in FIG.

  As shown in FIG. 12, the left and right electric motors 2 </ b> L and 2 </ b> R are operated by electric power supplied from a battery 63 mounted on the vehicle via an inverter 64. The electric motors 2L and 2R are individually controlled by an electronic control device (not shown), and can generate and output different torques.

The torque of the motor shaft 5a of the electric motors 2L, 2R is the gear ratio between the input gear shaft 12a of the reduction gears 3L, 3R and the input gear 12a of the intermediate gear shafts 13L, 13R and the large input side external gear 13a. And transmitted to the internal gears R _L and R _R of the torque difference amplifying device 30.

  Then, the output side small diameter gear 13b of the intermediate gear shafts 13L and 13R is engaged with the large diameter output gear 14a of the output gear shafts 14L and 14R via the torque difference amplifying device 30, and the output side small diameter gear 13b and the output gear 14a are engaged. The torque of the motor shaft 5a of the electric motors 2L, 2R is further increased by the gear ratio, and is output to the drive wheels 61L, 61R.

  The torque difference amplifying device 30 is configured by combining two planetary gear mechanisms 30L and 30R having the same three-element two-degree-of-freedom with coaxial intermediate gear shafts 13L and 13R. The planetary gear mechanisms 30L and 30R are single pinions. The model planetary gear mechanism is adopted.

The planetary gear mechanisms 30L and 30R are coaxially provided with sun gears S _L and S _R and internal gears R _L and R _R, and between these sun gears S _L and S _R and the internal gears R _L and R _R. a plurality of planetary gears P _L, P _R is close to the planetary gear P _L, provided the P _R rotatably supported by the sun gear S _L, S _R and the internal gear R _L, on R _R coaxial It is composed of planetary carriers C _L and C _R. Here, the sun gear S _L, S _R and the planetary gears P _L, P _R is the external gear having gear teeth on the outer circumference, the internal gear R _L, R _R is the internal gear having gear teeth on the inner peripheral is there. The planetary gears P _L and P _R mesh with the sun gears S _L and S _R and the internal gears R _L and R _R.

In the planetary gear mechanisms 30L, 30R, when the planet carriers C _L , C _R are fixed, the sun gears S _L , S _R and the internal gears R _L , R _R rotate in opposite directions, so the speed line shown in FIG. In the figure, the internal gears R _L and R _R and the sun gears S _L and S _R are arranged on the opposite side to the planetary carriers C _L and C _R.

As described above, the torque difference amplifying device 30 includes the first planetary gear mechanism 30L having the sun gear S _L , the planetary carrier C _L , the planetary gear P _L and the internal gear _RL , and the sun gear S _R , the planetary gear. carrier C _R, and a second planetary gear mechanism 30R having a planetary gear P _R and the internal gear R _R is configured by combining coaxially.

Then, coupled with the planet carrier C _L of the first planetary gear mechanism 30L and the sun gear S _R of the second planetary gear mechanism 30R form a first coupling member 31, the sun of the first planetary gear mechanism 30L a planet carrier C _R gear S _L and the second planetary gear mechanism 30R form a second coupling member 32 are coupled.

  Here, the torque TM1 generated by the electric motor 2L is transmitted to the intermediate gear shaft 13L by meshing the input gear 12a of the input gear shaft 12L and the input side external gear 13a, and the torque transmitted to the intermediate gear shaft 13L is It is transmitted to the output-side small gear 13b of the intermediate gear shaft 13L via the first planetary gear mechanism 30L, and the output-side small gear 13b of the intermediate gear shaft 13L and the output gear 14a of the output gear shaft 14L are engaged with each other to produce an output gear shaft. Drive torque TR is output from 14L to drive wheel 61L.

  The torque TM2 generated by the electric motor 2R is transmitted to the intermediate gear shaft 13R when the input gear 12a of the input gear shaft 12R and the input side external gear 13a are meshed, and the torque transmitted to the intermediate gear shaft 13R is the second torque. It is transmitted to the output-side small gear 13b of the intermediate gear shaft 13R via the planetary gear mechanism 30R, and the output-side small gear 13b of the intermediate gear shaft 13R and the output gear 14a of the output gear shaft 14R are meshed to drive from the output gear shaft 14R. A driving torque TL is output to the wheel 61R.

The outputs from the electric motors 2L and 2R are also given to the internal gears R _L and R _R of the two planetary gear mechanisms 30L and 30R, respectively, and the outputs from the first coupling member 31 and the second coupling member 32 are drive wheels. It is given to 61L and 61R.

  The 2nd coupling member 32 is comprised by the hollow shaft, the 1st coupling member 31 is penetrated in the inside, and the axis | shaft which comprises the 1st coupling member 31 and the 2nd coupling member 32 has a double structure. .

The first coupling member 31 has one end a rotation shaft of the (right end in the drawing) is the sun gear S _R, the other end (left end in the drawing) are provided through the sun gear S _L, connected to the planet carrier C _L Has been. The second coupling member 32 is a hollow shaft, one end (left end in the drawing) has a rotation shaft of the sun gear S _L, the other end (right end in the drawing) is connected to the planet carrier C _R. The first planetary gear mechanisms 30L and 30R are coupled by the first coupling member 31 and the second coupling member 32.

Next, since the torque difference amplifying device 30 is configured by combining two identical single pinion type planetary gear mechanisms 30L and 30R, it can be represented by two velocity diagrams as shown in FIG. Here, for easy understanding, the two speed diagrams are shifted up and down, the speed diagram of the left planetary gear mechanism 30L is shown on the upper side, and the speed diagram of the right planetary gear mechanism 30R is shown on the lower side. Originally, in the embodiment of FIG. 1, the torques TM1 and TM2 output from the electric motors 2L and 2R are respectively connected to the internal gears via the input side external gears 13a that mesh with the input gears 12a of the input gear shafts 12L and 12R. Since it is input to R _L and R _R , a reduction ratio is applied, and the drive torques TL and TR extracted from the torque difference amplifying device 30 are applied to the left and right drive wheels 61L via the output-side small gear 13b that meshes with the output gear 14a. , 61R is transmitted, so a reduction ratio is applied. Here, for easy understanding, hereinafter, in the speed diagram and the calculation formulas shown in FIG. 12, the reduction ratio is omitted, and the torques input to the internal gears R _L and R _R are TM1 and TM2. The drive torque remains TL and TR, and the drive torque extracted from the torque difference amplifying apparatus 30 remains TL and TR.

Two planetary gear mechanism 30L constituting the torque difference amplifier 30, 30R is due to the use of gear elements of the same number of teeth, the distance between the internal gear R _L and the planet carrier C _L in the velocity diagram, and an inner The distance between the gear R _R and the planet carrier C _R is equal, which is a. Further, the distance between the sun gear S _L and the planet carrier C _L and the distance between the sun gear S _R and the planet carrier C _R are also equal, which is b. The ratio of the length from the planet carrier C _L , C _R to the internal gear R _L , R _R and the length from the planet carrier C _L , C _R to the sun gear S _L , S _R is the ratio of the internal gear R _L , R _R It is equal to the ratio of the reciprocal number (1 / Zr) of the number of teeth Zr and the reciprocal number (1 / Zs) of the number of teeth Zs of the sun gears S _L and S _R. Therefore, it can be expressed as a = (1 / Zr), b = (1 / Zs).

The following equation (1) is calculated from the balance of moment M with reference to the point of R _R. In FIG. 8, the arrow direction M in the figure is the positive direction of the moment.
a * TR + (a + b) * TL- (b + 2a) * TM1 = 0 (1)

The following equation (2) is calculated from the balance of moment M with reference to point R _L.
-A.TL- (a + b) .TR + (b + 2a) .TM2 = 0 (2)

The following formula (3) is obtained from the sum of the formulas (1) and (2).
-B. (TR-TL) + (2a + b). (TM2-TM1) = 0
(TR-TL) = ((2a + b) / b). (TM2-TM1) (3)

  (2a + b) / b in the equation (3) is the torque difference amplification factor α. When a = 1 / Zr and b = 1 / Zs are substituted, α = (Zr + 2Zs) / Zr, and the following torque difference amplification factor α is obtained.

  α = (Zr + 2Zs) / Zr

In the present invention, the inputs from the electric motors 2L and 2R are the internal gears R _L and R _R , and the outputs to the drive wheels 61L and 61R are the sun gear S _R and the carrier C _L , and the sun gear S _L and the carrier C _R Become.

  When different torques TM1 and TM2 are generated by the two electric motors 2L and 2R to give an input torque difference ΔTIN (= (TM2−TM1)), the torque difference amplifier 30 amplifies the input torque difference ΔTIN and A driving torque difference α · ΔTIN larger than the torque difference ΔTIN can be obtained. That is, even if the input torque difference ΔTIN is small, the torque difference amplification device 30 can amplify the input torque difference ΔTIN with the above-described torque difference amplification factor α (= (Zr + 2Zs) / Zr). A drive torque difference ΔTOUT (= α · (TM2−TM1)) larger than the input torque difference ΔTIN can be given to the drive torques TL and TR transmitted to the drive wheel 61R.

  In the prior art 1 and the prior art 2, since the internal gear R is included in the left and right connecting members of the two planetary gear mechanisms constituting the torque difference amplifying device 105, the connecting member 1 that connects either the left or right internal gear and another member is used. One must have a larger diameter than the other internal gear R.

On the other hand, in the embodiment of the present invention, the connection between the two planetary gear mechanisms 30L and 30R constituting the torque difference amplifying device 30 is the sun gear S _L and the planet carrier C _R , and the sun gear S _R and the planet carrier C. _Since it is _L , a connecting member having a larger diameter than the internal gears R _L and R _R is not required. For this reason, in this invention, since the torque difference distribution mechanism can be made smaller than those of the prior art 1 and the prior art 2, the vehicle drive device 1 for an electric vehicle incorporating the torque difference distribution mechanism can be made smaller and lighter. Can be

  By reducing the size and weight of the vehicle driving device 1 for an electric vehicle, the degree of freedom of the vehicle body mounting layout of peripheral accessories is improved along with the vehicle body mounting layout of the vehicle driving device 1.

  Further, there is a merit that the vehicle interior space is expanded by downsizing the vehicle drive device 1.

  In the embodiment shown in FIG. 1, the case where the electric motors 2L and 2R are used as the two drive sources and the electric motors have the same maximum output and the same output characteristics is illustrated, but the two drive sources are not limited to this. I can't.

  The vehicle on which the vehicle drive device 1 is mounted is not limited to an electric vehicle or a hybrid electric vehicle, but may be, for example, a fuel cell vehicle that uses the first electric motor 2L and the second electric motor 2R as driving sources. Good.

  The present invention is not limited to the above-described embodiments, and can be further implemented in various forms without departing from the gist of the present invention.

1: Vehicle drive device 2L, 2R: Electric motor 3L, 3R: Deceleration device 4L, 4R: Motor housing 4aL, 4aR: Motor housing body 4bL, 4bR: Outer wall 4cL, 4cR: Inner wall 5: Rotor 5a: Motor shaft 6 : Stator 7: Sealing members 8a and 8b: Rolling bearing 9: Reduction gear housing 9a: Central housing 9bL and 9bR: Side housing 10: Bolt 11: Partition walls 12L and 12R: Input gear shaft 12a: Input gear shafts 13L and 13R: Intermediate Gear shaft 13a: Input side external gear 13b: Output side small diameter gears 14L, 14R: Output gear shaft 14a: Output gears 16a, 16b: Bearing fitting holes 17a, 17b: Rolling bearing 18: Oil seals 19a, 19b: Bearing fitting Holes 20a, 20b: Rolling bearing 30: Torque difference amplifying devices 30L, 30R : Planetary gear mechanism 31: first coupling member 32: second coupling member 33: carrier pins 34a and 34b: carrier flanges 35 and 36: hollow shaft portion 37: bearing 39: bearing 40: collar 41 and 42: spline 43: large Diameter portion 44: collar 45, 46: bearing 47, 48: thrust bearing 49: deep groove ball bearing 50: oil supply hole 51, 52: oil supply passage 53a, 53b: bearing fitting hole 54a, 54b: rolling bearing 55: oil seal 60 : Chassis 61L, 61R: Drive wheel 62L, 62R: Front wheel 63: Battery 64: Inverter 65a, 65b: Constant velocity joint 65c: Intermediate shaft 70: Lubricating oil introduction cylinder 70a: Cylindrical part 70b: Conical cylinder part 70c: Engaging claw 70d: engaging groove 70e: cut-out hole 71: toothless AM: electric vehicles C _L, C _R: the planet carrier M: Mento P _L, P _R: planetary gear _{R L,} R R: internal gear S _L, S _R: sun gear TM1, TM2: torque generated by the electric motor TL, TR: drive torque Zr: internal gear teeth Zs: Number of teeth of sun gear a, b: distance α: torque difference amplification factor ΔTIN: input torque difference ΔTOUT: drive torque difference

Claims (8)

  Between the two drive sources mounted on the vehicle and independently controllable and the left and right drive wheels, connected to the two drive sources, connected to the input gear shaft having the input gear, and the left and right drive wheels, An output gear shaft having an output gear, and at least one intermediate gear shaft that transmits power between the input gear shaft and the output gear shaft by meshing of the gear, and one of the reduction gears Two planetary gear mechanisms are combined on the same axis as the intermediate gear shaft, and a specific element of one planetary gear mechanism and a specific element of the other planetary gear mechanism are interconnected to generate power from two drive sources. In a vehicle drive device incorporating a torque difference amplifying device that amplifies and transmits a torque difference to the left and right drive wheels, an intermediate gear shaft of the speed reducer incorporating the torque difference amplifying device is used for each gear shaft constituting the speed reducer The lowest place from the ground A vehicle drive device characterized in that the vehicle drive device is arranged in a position.   The oil level of the lubricating oil sealed in the speed reducer housing that houses the speed reducer is set to a height at which the planetary gear positioned at the lowest point of the planetary gear mechanism that constitutes the torque difference amplifying device is immersed in the stationary state. The vehicle drive device according to claim 1, wherein the vehicle drive device is set.   3. The vehicle drive device according to claim 1, wherein an oil supply hole for lubrication penetrating right and left is provided in an axial center of an intermediate gear shaft of a speed reducer incorporating the torque difference amplifying device.   4. The vehicle drive device according to claim 3, wherein a radial oil supply passage is provided in the axial oil supply hole.   5. A lubricating oil introduction cylinder for guiding lubricating oil sealed in a reduction gear housing that houses the reduction gear device is attached to an end portion on the outboard side of the axial oil supply hole. The vehicle drive device described in 1.   The said lubricating oil introduction cylinder consists of a cylindrical part and a conical cylinder part narrowed narrowly toward the outer end surface of an oil supply hole from the edge part of the inboard side of a cylindrical part. Vehicle drive device.   An engagement claw protruding to the outer peripheral side is provided in the cylindrical portion of the lubricating oil introduction cylinder, and the engagement groove engaged with the engagement claw is a hollow shaft of an intermediate gear shaft of a reduction gear incorporating a torque difference amplifying device. The vehicle drive device according to claim 6, wherein the vehicle drive device is provided on an inner peripheral surface of the portion.   The vehicle drive device according to any one of claims 3 to 7, wherein the intermediate gear shaft and the torque difference amplifying device are connected by a spline, and a missing tooth is provided on a part of the teeth of the spline.

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