DRIVE FORCE DISTRIBUTION APPARATUS

Abstract

A drive force distribution apparatus is provided with an input shaft, first and second output shafts, a first epicyclic gear group, a second epicyclic gear group and a motor/generator. The first epicyclic gear group has two degrees of freedom, with the first epicyclic gear group including a first gear coupled to the input shaft, a second gear coupled to the first output shaft and a third gear. The second epicyclic gear group has two degrees of freedom, with the second epicyclic gear group including a first gear coupled to the input shaft, a second gear coupled to the second output shaft and a third gear. The motor/generator is operatively coupled to the third gears of the first and second epicyclic gear groups so that mutually different drive forces are transmitted from the motor/generator to the first and second epicyclic gear groups.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the attached drawings which form a part of this original disclosure:

FIG. 1 is a longitudinal side cross-sectional view of a drive force distribution apparatus that is configured as a center differential gear apparatus for driving the wheels of a four-wheel-drive vehicle in accordance with a first embodiment of the present invention;

FIG. 2 is a simplified perspective view of the drive force distribution apparatus showing a motor-output transmission system of a motor/generator for controlling the distribution of drive force in the drive force distribution apparatus in accordance with the first embodiment of the present invention;

FIG. 3 is a simplified schematic view (skeleton diagram) of the drive force distribution apparatus of the first embodiment of the present invention;

FIG. 4 is a collinear graph of the drive force distribution apparatus in accordance with the first embodiment of the present invention;

FIG. 5 is a graph of the operation characteristics of the drive force distribution apparatus in accordance with the first embodiment of the present invention;

FIG. 6 is a performance line graph that illustrates the general correlation between the number of motor rotations and the motor torque of a motor/generator;

FIG. 7 is a transverse cross sectional view of a differential-limiting drive force distribution apparatus configured as a differential gear apparatus provided between the left and right driven wheels of a vehicle in accordance with a second embodiment of the present invention;

FIG. 8 is a simplified perspective view of the differential-limiting drive force distribution apparatus showing the output transmission system of a (differential-limiting) motor/generator for controlling differences in output rotation in the differential-limiting drive force distribution apparatus in accordance with the second embodiment of the present invention;

FIG. 9 is a simplified schematic view (skeleton diagram) of the differential-limiting drive force distribution apparatus in accordance with the second embodiment of the present invention;

FIG. 10 is a graph of the operation characteristics of the differential-limiting drive force distribution apparatus in accordance with the second embodiment of the present invention; and

FIG. 11 is a series of collinear graphs of the drive force distribution apparatus in accordance with the second embodiment of the present invention, with graph (a) showing where the drive force to the left wheel and the drive force to the right wheel are the same and the distribution of the drive force to the left and right wheels is 50:50; graph (b) showing where the drive force to the left wheel is larger than the drive force to the right wheel when turning right; and graph (c) showing where the drive force to the left wheel is smaller than the drive force to the right wheel when turning left.

Claims

1. A drive force distribution apparatus comprising: an input shaft;first and second output shafts;a first epicyclic gear group having two degrees of freedom, with the first epicyclic gear group including a first gear coupled to the input shaft, a second gear coupled to the first output shaft and a third gear;a second epicyclic gear group having two degrees of freedom, with the second epicyclic gear group including a first gear coupled to the input shaft, a second gear coupled to the second output shaft and a third gear; anda motor/generator operatively coupled to the third gears of the first and second epicyclic gear groups so that mutually different drive forces are transmitted from the motor/generator to the first and second epicyclic gear groups.

2. The drive force distribution apparatus according to claim 1, further comprising a motor-output transmission system including a pair of fourth gears engaged with the third gears of the first and second epicyclic gear groups, respectively, and a pair of fifth gears engaged with each other and coupled with the fourth gears, respectively, to rotate therewith,the motor-output transmission system being connected to the motor/generator to transmit a torque from the motor/generator to rotate the third gears of the first and second epicyclic gear groups in mutually opposite directions via the fourth and fifth gears.

3. The drive force distribution apparatus according to claim 1, wherein the first gears of the first and second epicyclic gear groups are both configured as sun gears that are coaxially arranged.

4. The drive force distribution apparatus according to claim 1, wherein the second gears of the first epicyclic gear group are configured as a plurality of first planet gears; andthe second gears of the second epicyclic gear group are configured as a plurality of second planet gears; andthe third gears of the first and the second epicyclic gear groups are both configured as ring gears.

5. The drive force distribution apparatus according to claim 4, wherein the first epicyclic gear group further includes a first carrier that rotatably supports the first planet gears together with the first carrier being operatively connected to the first output shaft to rotate therewith; andthe second epicyclic gear group further includes a second carrier that rotatably supports the second planet gears together with the second carrier being operatively connected to the second output shaft to rotate therewith t.

6. The drive force distribution apparatus according to claim 1, wherein the first and second gears of the first and second epicyclic gear groups have identical to gear ratios; andthe second and third gears of the first and second epicyclic gear groups have identical to gear ratios.

7. The drive force distribution apparatus according to claim 1, wherein the third gears of the first and the second epicyclic gear groups are coupled to the motor/generator to be rotated by the motor/generator to control a difference in rotational velocities of the first and second output shafts that are connected to the second gears of the first and second epicyclic gear groups, respectively.

8. The drive force distribution apparatus according to claim 7, wherein the motor/generator is configured to generate electricity when limiting rotation of the third gears of the first and the second epicyclic gear groups to limit the difference in rotational velocities of the two output shafts.

9. A drive force distribution apparatus comprising: first differential means for providing two degrees of freedom to transmit a drive force from an input shaft to a first output shaft;second differential means for providing two degrees of freedom to transmit the drive force from the input shaft to a second output shaft; andtorque providing means for providing a torque for distribution of the drive force from the input shaft to the first and second output shafts,each of the first and second differential means including first rotational transmitting means for transmitting the drive force from the input shaft, second rotational transmitting means for selectively outputting the drive force to a respective one of the first and second output shafts, and third rotational transmitting means for receiving the torque in mutually opposite directions from the torque providing means.

10. The drive force distribution apparatus according to claim 9, further comprising: conversion means for converting the torque for controlling distribution of the drive force into the opposite directions between the third rotational transmitting means of the first and second differential means.

11. The drive force distribution apparatus according to claim 9, wherein the torque providing means further comprises rotation limiting means for limiting rotation in mutually opposite directions of the third rotational transmitting means of the first and second differential means and limiting a difference in rotational velocity between the second rotational transmitting means of the first and second differential means.

12. A method for distributing drive force comprising: providing a first differential unit with two degrees of freedom using a first element, a second element and a third element;providing a second differential unit with two degrees of freedom using a first element, a second element and a third element;inputting a drive force transmitted from an input shaft to the first elements of the two differential units;distributing the drive force to a pair of output shafts via the second elements of the first and second differential units; andproviding a torque for controlling distribution of the drive force in a direction so that the third elements of the two differential units rotate in mutually opposite directions to selectively increase the drive force that is distributed to one of the output shafts and reduce the drive force distributed to the other of the output shafts.