JP6011132B2 - Driving force distribution device - Google Patents

Description

  The present invention relates to a driving force distribution device useful as a transfer for a four-wheel drive vehicle, and more particularly to a traction transmission type driving force distribution device.

As a traction force transmission type driving force distribution device, a device as described in Patent Document 1, for example, has been conventionally known.
The driving force distribution device described in this document includes a first roller mechanically coupled to the transmission system of the main driving wheel and a second roller mechanically coupled to the driving system of the driven wheel. A part of the torque to the main driving wheel can be distributed and output to the driven wheel by bringing the first roller and the second roller into radial contact with each other on their outer peripheral surfaces. is there.

  In such a driving force distribution device, by adjusting the radial pressing force between the first roller and the second roller, the torque transmission capacity between these rollers, and accordingly, the driving force distribution between the main driving wheel and the sub driving wheel Can be controlled.

  As a mechanism for performing this driving force distribution control, Patent Document 1 describes that the second roller is made to be radially relative to the first roller by turning the shaft portion of the second roller around the fixed axis of the housing with a motor or the like. A configuration has been proposed in which the displacement can be controlled to control the radial pressing force between the first roller and the second roller, that is, the distribution of the driving force between the main driving wheel and the sub driving wheel.

  That is, the outer periphery of the hollow crankshaft is rotatably provided around the fixed axis of the housing, and the shaft portion of the second roller is rotatably supported in the eccentric hollow hole of the hollow crankshaft. By rotating the second roller around the fixed axis by rotation around the fixed axis, the driving force distribution control between the main drive wheel and the sub drive wheel is controlled by adjusting the radial pressing force of the second roller against the first roller. A possible configuration is proposed.

JP 2009-173261 A (FIG. 5)

  By the way, in the driving force distribution device of the above type, when the second roller is mechanically coupled to the drive system of the driven wheel, the shaft portion of the second roller is exposed from the housing of the driving force distribution device at one end, The drive wheel transmission system is coupled according to the exposed end portion of the second roller shaft portion exposed from the housing.

  In order to ensure a seal between the exposed end portion of the second roller shaft portion and the housing despite the above rotation of the second roller, Patent Document 1 describes the second roller shaft portion exposed from the housing. A liquid-tight sealing structure is also proposed in which a seal is interposed between the inner and outer circumferences of the hollow crankshaft and the second roller shaft portion and the housing at the exposed end portion.

  However, in such a liquid-tight sealing structure, the annular space between the inner periphery of the hollow crankshaft and the second roller shaft portion becomes a dead end space due to the presence of the seal between them, and the scraped roller that reaches here The raised oil cannot return to the oil reservoir in the housing, and the hydraulic oil that has entered the annular cavity tends to stay here.

  If the fluidity of the hydraulic fluid in the annular space between the hollow crankshaft and the second roller shaft is poor, the lubrication and cooling capacity of the hydraulic oil is insufficient, especially between the hollow crankshaft and the second roller shaft. As a result, the friction of the bearing that controls the rotation support increases, resulting in a problem that transmission efficiency is deteriorated and durability is lowered.

  The present invention improves the driving force distribution device so as to improve the fluidity of the hydraulic oil in the annular space between the hollow crankshaft and the second roller shaft, and deteriorates the transmission efficiency and durability due to the lack of lubrication / cooling capability. The purpose is to eliminate the problems related to the decline of sex.

For this purpose, the driving force distribution device according to the present invention is configured as follows.
First of all, to explain the premise driving force distribution device,
Distributing the driving force to the driven wheels by bringing the first roller that rotates together with the main drive wheel transmission system and the second roller that rotates together with the driven wheel transmission system into radial contact with each other on the outer peripheral surfaces of both. Is possible,
The respective shaft portion in the axial direction on both sides of the second roller, and rotatably supported via an inner peripheral bearings in the eccentric hollow hole of the crankshaft, which is supported by rotatably periphery bearings around a fixed axis of housing, the By rotating the crankshaft around the fixed axis by rotating the crankshaft around the fixed axis , the radial pressing force of the second roller against the first roller is adjusted to adjust between the main driving wheel and the driven wheel. Drive power distribution can be controlled,
And the tip of the second roller shaft portion of one of the shaft portion is exposed from the housing to couple the exposed tip of the second roller shaft portion of one said to said auxiliary driving wheel transmission system in the axial direction on both sides of the second roller In addition, the inner and outer circumferences of the crankshaft related to the one second roller shaft portion and the space between the one second roller shaft portion and the housing are respectively in the vicinity of the exposed tip of the one second roller shaft portion. Liquid-tightly sealed with a peripheral seal and an outer peripheral seal .

The driving force distribution device of the present invention is based on the above premise configuration.
An inner periphery defined between the one second roller shaft portion and the crank shaft related to the one second roller shaft portion by an inner bearing and an inner seal related to the one second roller shaft portion. A side annular cavity, and an outer circumferential side annular cavity defined between the housing and the crankshaft associated with the one second roller shaft portion by the outer peripheral bearing and the outer periphery seal associated with the one second roller shaft portion. Is characterized in that a radial oil hole is provided in the crankshaft related to the one second roller shaft portion .

According to the driving force distribution device of the present invention, the following effects can be obtained.
That is, after the roller scooping oil reaches the inner circumferential annular cavity , it does not stay here, but passes through the radial oil hole provided in the crankshaft related to one of the second roller shafts to the outer circumferential annular cavity. lead, it is possible to return from the outer circular cavity in an oil reservoir in the housing, a good fluidity of the hydraulic fluid in the inner circumferential side annular cavity.
For this reason, the lubrication / cooling capacity by the hydraulic oil in the inner circumferential side annular space can be kept high, and the inner circumference bearing related to one of the second roller shafts can be reliably lubricated / cooled, and the transmission efficiency can be improved. It is possible to reliably solve the above-described conventional problems related to deterioration and deterioration of durability.

1 is a schematic plan view showing a power train of a four-wheel drive vehicle including a driving force distribution device according to an embodiment of the present invention when viewed from above the vehicle. FIG. 2 is a longitudinal side view of the driving force distribution device in FIG. FIG. 3 is a longitudinal front view showing a crankshaft used in the driving force distribution device shown in FIG. FIG. 3 is an operation explanatory diagram of the driving force distribution device shown in FIG. 2, wherein (a) is an operation explanatory diagram showing a separation state of the first roller and the second roller at a position where the crankshaft rotation angle is 0 ° of the reference point; b) is an operation explanatory diagram showing the contact state of the first roller and the second roller when the crankshaft rotation angle is 90 °, and (c) is the first roller when the crankshaft rotation angle is 180 °. FIG. 6 is an operation explanatory view showing a contact state of the second roller.

Hereinafter, embodiments of the present invention will be described in detail based on the illustrated examples.
<Configuration of Example>
FIG. 1 is a schematic plan view showing a power train of a four-wheel drive vehicle provided with a driving force distribution device 1 according to an embodiment of the present invention as a transfer as viewed from above the vehicle.

The four-wheel drive vehicle in FIG. 1 is a rear-wheel drive vehicle in which rotation from the engine 2 is transmitted to the left and right rear wheels 6L and 6R through the rear propeller shaft 4 and the rear final drive unit 5 after being shifted by the transmission 3. As a base vehicle,
A part of the torque to the left and right rear wheels (main drive wheels) 6L, 6R is transmitted to the left and right front wheels (slave drive wheels) 9L, 9R through the front propeller shaft 7 and the front final drive unit 8 sequentially by the driving force distribution device 1. By doing so, the vehicle can be driven by four-wheel drive.

  As described above, the driving force distribution device 1 distributes and outputs a part of the torque to the left and right rear wheels (main driving wheels) 6L and 6R to the left and right front wheels (secondary driving wheels) 9L and 9R. (Main drive wheels) 6L, 6R and left and right front wheels (secondary drive wheels) 9L, 9R to determine the drive force distribution ratio. In this embodiment, this drive force distribution device 1 is as shown in FIG. Configure.

In FIG. 2, reference numeral 11 denotes a housing of the driving force distribution device 1, and the input shaft 12 and the output shaft 13 are horizontally inclined in the housing 11 so that the respective rotation axes O ₁ and O ₂ intersect with each other. To do.
The input shaft 12 is rotatably supported with respect to the housing 11 by ball bearings 14 and 15 at both ends thereof.
Both ends of the input shaft 12 are protruded from the housing 11 under liquid-tight sealing by seal rings 25 and 26, respectively.
2, the left end of the input shaft 12 is drivingly coupled to the output shaft of the transmission 3 (see FIG. 1), and the right end is drivingly coupled to the rear final drive unit 5 via the rear propeller shaft 4 (see FIG. 1).

Arranged near the both ends of the input shaft 12 and the output shaft 13, respectively, a pair of bearing supports 16, 17 are installed between the input / output shafts 12, 13, and the bearing supports 16, 17 are arranged in the middle of each bolt. (Not shown) is attached to the axially opposed inner wall of the housing 11.
Roller bearings 21 and 22 are interposed between the bearing supports 16 and 17 and the input shaft 12 so that the input shaft 12 can be rotated with respect to the bearing supports 16 and 17. However, the input shaft 12 is rotatably supported in the housing 11.

A first roller 31 is integrally formed coaxially in the middle of the axial direction of the input shaft 12 between the bearing supports 16 and 17 (between the roller bearings 21 and 22) so that the first roller 31 can be pressed into the radial direction. The second roller 32 is coaxially and integrally formed at the middle position of the output shaft 13 in the axial direction.
The outer peripheral surfaces 31a and 32a of the first roller 31 and the second roller 32 are conical tapered surfaces that can be in line contact with each other even when the input shaft 12 and the output shaft 13 are inclined as described above.

The output shaft 13 pivots into the housing 11 via the bearing supports 16 and 17 by pivotally supporting the bearing supports 16 and 17 near both ends (second roller shaft portions) 13L and 13R. Support as possible.
Thus, when the output shaft 13 (13L, 13R) is rotatably supported with respect to the bearing supports 16, 17, the following eccentric support structure is used.

A hollow outer shaft type crankshaft 51L, 51R is loosely fitted between the output shaft 13 (13L, 13R) and the bearing supports 16, 17 through which the output shaft 13 (13L, 13R) passes.
It protrudes from the housing 11 in crankshafts 51L and the output shaft 13 above end in the left side of FIG. 2, respectively (one second roller shaft portion 13L of), projecting sealing ring between the housing 11 and crankshaft 51L in section (outer circumference a seal) 27 together with the intervention, by interposing the crankshaft 51L and output shaft 13 (13L) seal ring between (inner peripheral seal) 28, crankshafts 51L and the output shaft 13 protrudes from the housing 11 of the (13L) Each protrusion is liquid-tightly sealed.

  In FIG. 2, the left end 13L of the output shaft 13 discharged from the housing 11 is drivingly coupled to the left and right front wheels 9L and 9R via the front propeller shaft 7 (see FIG. 1) and the front final drive unit 8.

Roller bearings (inner peripheral bearings) 52L and 52R are interposed between the hollow holes 51La and 51Ra (radius Ri) of the crankshafts 51L and 51R and the corresponding ends 13L and 13R of the output shaft 13, respectively. (13L, 13R) and crankshaft 51L, hollow hole 51La of 51R, in 51Ra, supports that can freely rotate around these central axis O _2.

As clearly shown in FIG. 3, the hollow holes 51La and 51Ra (center axis O ₂ ) of the crankshafts 51L and 51R are eccentric hollow holes eccentric to the outer peripheral portions 51Lb and 51Rb (center axis O ₃ and radius Ro). The central axis O ₂ of the eccentric hollow holes 51La and 51Ra is offset from the central axis O ₃ of the outer peripheral portions 51Lb and 51Rb by the eccentricity ε between them.
The outer peripheral portions 51Lb and 51Rb of the crankshafts 51L and 51R are rotatably supported in bearing supports 16 and 17 on the corresponding side via roller bearings (outer peripheral bearings) 53L and 53R,
At this time, the crankshafts 51L and 51R, together with the second roller 32, are positioned in the axial direction by the thrust bearings 54L and 54R.

Ring gears 51Lc and 51Rc of the same specification are integrally provided at adjacent ends of the crankshafts 51L and 51R facing each other.
A common crankshaft drive pinion 55 is engaged with each of the ring gears 51Lc and 51Rc, and the crankshaft drive pinion 55 is coupled to the pinion shaft 56.

  As described above, when the crankshaft drive pinion 55 is engaged with the ring gears 51Lc and 51Rc, the rotational positions where the outer peripheral portions 51Lb and 51Rb of the crankshafts 51L and 51R are aligned in the circumferential direction and in phase with each other. In this state, the crankshaft drive pinion 55 is engaged with the ring gears 51Lc and 51Rc.

Both ends of the pinion shaft 56 are rotatably supported with respect to the housing 11 by bearings 56a and 56b.
The right end of the pinion shaft 56 on the right side of FIG.
An output shaft 35a of an inter-roller pressing force control motor 35 attached to the housing 11 is drivingly coupled to the exposed end surface of the pinion shaft 56 by serration fitting or the like.

Therefore, when the rotational position of the crankshafts 51L, 51R is controlled by the inter-roller radial pressing force control motor 35 via the pinion 55 and the ring gears 51Lc, 51Rc,
The rotation axis O ₂ of the output shaft 13 and the second roller 32 turns around the central axis O ₃ along a locus circle α indicated by a broken line in FIG.

The second roller 32 is rotated by the rotation axis O ₂ (second roller 32) along the locus circle α in FIG. 3, but the first roller 31 will be described in detail later, as shown in FIGS. 4 (a) to 4 (c). As the rotation angle θ of the crankshafts 51L and 51R increases, the radius L1 between the first roller 31 and the second roller 32 increases. It can be made smaller than the sum of the radius.
Due to such a decrease in the distance L1 between the roller shafts, the radial pressing force of the second roller 32 against the first roller 31 (the transmission torque capacity between the rollers: traction transmission capacity) increases, and according to the degree of decrease in the distance L1 between the roller axes. The inter-roller radial pressing force (inter-roller transmission torque capacity: traction transmission capacity), that is, the driving force distribution ratio can be arbitrarily controlled.

As shown in FIG. 4 (a), in this embodiment, the second roller rotation axis O ₂ is located immediately below the crankshaft rotation axis O ₃ and the inter-axis distance L1 between the first roller 31 and the second roller 32 is The distance L1 between the roller axes at the maximum bottom dead center is made larger than the sum of the radius of the first roller 31 and the radius of the second roller 32.
Thus, at the bottom dead center of the crankshaft rotation angle θ = 0 °, the first roller 31 and the second roller 32 are not pressed against each other in the radial direction, and traction transmission is performed between the rollers 31 and 32. No traction transmission capacity = 0 can be obtained,
The traction transmission capacity can be arbitrarily controlled between 0 at the bottom dead center and the maximum value obtained at the top dead center (θ = 180 °) shown in FIG.

  In the present embodiment, the description will be made assuming that the rotation angle reference point of the crankshafts 51L and 51R is the bottom dead center of the crankshaft rotation angle θ = 0 °.

<Driving force distribution action>
The drive force distribution action of the transfer 1 described above with reference to FIGS.
On the other hand, the torque that has reached the input shaft 12 of the transfer 1 from the transmission 3 (see FIG. 1) passes directly from the input shaft 12 through the rear propeller shaft 4 and the rear final drive unit 5 (both see FIG. 1) to the left and right rear wheels 6L. , 6R (main drive wheel).

On the other hand, the transfer 1 controls the rotational position of the crankshafts 51L and 51R via the pinion 55 and the ring gears 51Lc and 51Rc by the motor 35, and the distance L1 between the roller axes (see FIG. 4) is set to the first roller 31 and the second roller 32. Since the rollers 31, 32 have a torque transfer capacity between the rollers according to the radial mutual pressing force, the left and right rear wheels 6L, 6R (main A part of the torque to the drive wheels) is directed from the first roller 31 to the output shaft 13 via the second roller 32, and the left and right front wheels 9L and 9R (secondary drive wheels) can also be driven.
Thus, the vehicle is capable of four-wheel drive running by driving all of the left and right rear wheels 6L and 6R (main drive wheels) and the left and right front wheels (secondary drive wheels) 9L and 9R.

Note that the radial pressing reaction force between the first roller 31 and the second roller 32 during the transmission is received by the bearing supports 16 and 17 which are rotation support plates common to them, and does not reach the housing 11.
The radial pressing reaction force is 0 when the crankshaft rotation angle θ is 0 ° to 90 °, and increases as θ increases while the crankshaft rotation angle θ is 90 ° to 180 °. The maximum value is obtained when the crankshaft rotation angle θ is 180 °.

During such four-wheel drive traveling, the rotation angle θ of the crankshafts 51L and 51R is 90 ° of the reference position as shown in FIG. 4 (b), and the first roller 31 and the second roller 32 are mutually connected. When pressed by a radial pressing force corresponding to the offset amount OS at the time of radial pressing,
Power is transmitted to the left and right front wheels (sub driven wheels) 9L and 9R with a traction transmission capacity corresponding to the offset amount OS between these rollers.

  Then, the crankshafts 51L and 51R are rotated from the reference position in FIG. 4 (b) toward the top dead center of the crankshaft rotation angle θ = 180 ° shown in FIG. 4 (c) to increase the crankshaft rotation angle θ. As a result, the distance L1 between the roller shafts further decreases, and the mutual overlap amount OL of the first roller 31 and the second roller 32 increases. As a result, the first roller 31 and the second roller 32 increase the radial mutual pressing force. Thus, the traction transmission capacity between these rollers can be increased.

When the crankshafts 51L and 51R reach the top dead center position in FIG. 4 (c), the first roller 31 and the second roller 32 are in the radial direction with a maximum radial pressing force corresponding to the maximum overlap amount OL. The traction transmission capacity between them can be maximized.
The maximum overlap amount OL is the sum of the eccentric amount ε between the second roller rotation axis O ₂ and the crankshaft rotation axis O ₃ and the offset amount OS described above with reference to FIG. 4B.

As is apparent from the above description, the crankshaft rotation angle is controlled by rotating the crankshafts 51L and 51R from the rotation position of the crankshaft rotation angle θ = 0 ° to the rotation position of the crankshaft rotation angle θ = 180 °. As θ increases, the traction transmission capacity between rollers can be continuously changed from 0 to the maximum value.
Conversely, by rotating the crankshaft 51L, 51R from the rotation position of the crankshaft rotation angle θ = 180 ° to the rotation position of θ = 0 °, the traction transmission between the rollers is reduced as the crankshaft rotation angle θ decreases. The capacity can be continuously changed from the maximum value to 0, and the traction transmission capacity between the rollers can be freely controlled by rotating the crankshafts 51L and 51R.

<Lubrication structure of transfer>
When lubricating the transfer (driving force distribution device) 1 according to the present embodiment described above with reference to FIG. 2, the hydraulic oil stored in the lower portion of the housing 11 is removed while the first roller 31 and the second roller 32 are rotating. This is accomplished by scooping up and reaching the lubrication points of each part while the scooping oil falls.

The left end portion 13L in FIG. 2 to which the left and right front wheels 9L, 9R, which are the driven wheels, of the lubrication point according to the present invention, that is, the output shaft 13 (13L, 13R) constituting the shaft portion of the second roller 32, The dropping path of the scraped oil toward the annular space (inner circumferential side annular space) between the crankshaft 51L (hollow hole 51La) is as follows.

  The hydraulic oil scooped up by the rotation of the first roller 31 and the second roller 32 was interposed between the second roller 32 and the ring gear 51Lc from the gap between the second roller 32 and the ring gear 51Lc as indicated by an arrow A1. It passes through the thrust bearing 54L and enters the annular space between the left end portion 13L of the output shaft 13 and the crankshaft 51L (hollow hole 51La).

  Therefore, since the seal ring 28 is interposed between the left end portion 13L of the output shaft 13 and the crankshaft 51L (hollow hole 51La) at the connecting portion of the front wheel drive system, the left end portion 13L of the output shaft 13 and the crankshaft 51L There is no passage through which the hydraulic oil that has entered the annular space between the (hollow holes 51La) escapes and tends to stay in this annular space.

The reason why the seal ring 28 is interposed between the left end portion 13L of the output shaft 13 and the crankshaft 51L (hollow hole 51La) at the coupling portion of the front wheel drive system is as follows.
The second roller 32 (output shaft 13) rotates around its own axis O ₂ and, as described above, pivots around the rotational axis O ₃ of the crankshaft 51L. It is necessary to liquid-tightly seal the left end portion 13L of the output shaft 13 protruding from the housing 11 with respect to the housing 11.

  Therefore, in the present embodiment, as described above, the crankshaft 51L and the left end portion 13L of the output shaft 13 are protruded from the housing 11 at the left end of FIG. By interposing, and by interposing a seal ring 28 between the crankshaft 51L and the output shaft 13 (13L), the projecting ends of the crankshaft 51L and the output shaft left end portion 13L protruding from the housing 11 are liquid-tightly sealed.

According to the liquid-tight sealing structure, the crankshaft 51L is not displaced relative to the housing 11 in the radial direction while the crankshaft 51L is rotating and the output shaft left end portion 13L is rotating and turning. The shaft left end 13L is not radially displaced relative to the crankshaft 51L,
The second roller 32 (the output shaft 13) even though pivots about the rotation axis O ₃ of the crank shaft 51L, is fluid-tight seal with respect to the housing 11 at the left end portion 13L of the output shaft 13 projecting from the housing 11 be able to.

However, the seal ring 28 prevents the hydraulic oil that has entered the annular space between the left end portion 13L of the output shaft 13 and the crankshaft 51L (hollow hole 51La) from escaping, so that the inflowing hydraulic oil can flow into the annular space. I will stay.
Thus, if the fluidity of the hydraulic oil in the annular space between the crankshaft 51L and the second roller shaft portion 13L is poor, the lubrication / cooling capacity by the hydraulic oil is insufficient, especially the crankshaft 51L and the second roller shaft portion. There is a problem that the friction of the roller bearing 52L, which controls the rotation support between 13L, is increased, leading to deterioration of transmission efficiency and deterioration of durability.

In this embodiment, to solve this problem, as shown in FIG. 2, the hollow crankshaft 51L is provided with a radial oil hole 51Ld communicating between the inner and outer circumferences at the axial position between the seal ring 28 and the roller bearing 52L. It is a thing.
The radial oil holes 51Ld are a large number of oil holes arranged at equal intervals in the circumferential direction, and the total opening area corresponds to the required amount of lubricating oil.

As a result, after flowing through the roller bearing 52L as indicated by arrows A1 and A2 , the hydraulic oil that has entered the annular space (inner circumferential side annular space) between the crankshaft 51L and the second roller shaft portion 13L becomes the arrow A3. As shown, it passes through the radial oil hole 51Ld to reach the annular space (outer circumferential side annular space) between the crankshaft 51L and the housing 11, and from this annular space (outer circumferential side annular space) to the lower oil reservoir of the housing 11 Try to get back.

<Effect of Example>
According to the lubrication structure of the driving force distribution device according to the above-described embodiment, the radial oil hole 51Ld is provided in the crankshaft 51L.
Since the fluidity of the hydraulic oil in the annular space between the crankshaft 51L and the second roller shaft portion 13L is improved as described above,
Crankshaft 51L can maintain high lubrication / cooling capacity due to hydraulic oil in the annular space.
In addition, the roller bearing 52L that controls rotation support between the second roller shaft portion 13L can also be reliably lubricated and cooled, and the above-described conventional problems related to the deterioration of transmission efficiency and the decrease in durability can be surely solved. .

1 Driving force distribution device (transfer)
2 Engine
3 Transmission
4 Rear propeller shaft
5 Rear final drive unit
6L, 6R Left and right rear wheels (main drive wheels)
7 Front propeller shaft
8 Front final drive unit
9L, 9R Left and right front wheels (sub driven wheels)
11 Housing
12 Input shaft
13 Output shaft
13L, 13R Second roller shaft
16,17 Bearing support
31 1st roller
32 2nd roller
35 Roller radial pressing force control motor
51L, 51R Crankshaft
51La, 51Ra eccentric hollow hole
51Lb, 51Rb Outer part
51Lc, 51Rc Ring gear
51Ld radial oil hole
55 Crankshaft drive pinion
56 Pinion shaft

Claims (1)

Distributing the driving force to the driven wheels by bringing the first roller that rotates together with the main drive wheel transmission system and the second roller that rotates together with the driven wheel transmission system into radial contact with each other on the outer peripheral surfaces of both. Is possible,
Wherein each shaft portion in the axial direction on both sides of the second roller, and rotatably supported via an inner peripheral bearings in the eccentric hollow hole of the crankshaft, which is supported by rotatably periphery bearings around a fixed axis of housing, the By rotating the crankshaft around the fixed axis by rotating the crankshaft around the fixed axis , the radial pressing force of the second roller against the first roller is adjusted to adjust between the main driving wheel and the driven wheel. Drive power distribution can be controlled,
And the tip of the second roller shaft portion of one of the shaft portion is exposed from the housing to couple the exposed tip of the second roller shaft portion of one said to said auxiliary driving wheel transmission system in the axial direction on both sides of the second roller In addition, the inner and outer circumferences of the crankshaft related to the one second roller shaft portion and the space between the one second roller shaft portion and the housing are respectively in the vicinity of the exposed tip of the one second roller shaft portion. In the driving force distribution device that is liquid-tightly sealed by the peripheral seal and the peripheral seal ,
An inner periphery defined between the one second roller shaft portion and the crank shaft related to the one second roller shaft portion by an inner bearing and an inner seal related to the one second roller shaft portion. A side annular cavity, and an outer circumferential annular cavity defined between a crankshaft associated with the one second roller shaft portion and the housing by an outer peripheral bearing and an outer periphery seal associated with the one second roller shaft portion. A driving force distribution device characterized in that a radial oil hole that communicates with the first roller shaft portion is provided in a crankshaft associated with the one second roller shaft portion .

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