Universal driving device

1. A universal driving apparatus comprising:

a sun gear rotatably provided;

a ring gear, wherein a rotation axis of the ring gear is moved relative to a rotation axis of the sun gear in a plane of rotation parallel to a plane of rotation of the sun gear;

at least one gear train configured to allow relative motion between the rotation axes of the sun gear and the ring gear and to form a continuous power transmission state between the sun gear and the ring gear; and

at least one balance gear only engaged with the ring gear.

2. The universal driving apparatus of claim 1 , wherein each of the at least one gear train is provided through a plurality of links, connection angles between which are changed depending on the relative motion between the rotation axes of the sun gear and the ring gear.

3. The universal driving apparatus of claim 2 ,

wherein the plurality of links includes a first link, a first end of which is connected to the rotation axis of the sun gear and a second link, a first end of which is connected to a second end of the first link, and

wherein a joint pinion of the at least one gear train and having a same number of gear teeth as the sun gear is provided at a connection portion between the second end of the first link and the first end of the second link.

4. The universal driving apparatus of claim 3 ,

wherein a final pinion of the at least one gear train and engaged with the ring gear is provided at a second end of the second link, and

wherein the final pinion has a same number of gear teeth as the sun gear.

5. The universal driving apparatus of claim 4 , wherein the final pinion is configured to transmit power from the sun gear to the ring gear by a series of gears through the joint pinion.

6. The universal driving apparatus of claim 4 , wherein the at least one gear train includes a plurality of gear trains provided in a circumferential direction of the sun gear.

7. The universal driving apparatus of claim 6 , wherein rotation axes of respective final pinions of the plurality of gear trains and a rotation axis of the at least one balance gear are supported by a carrier.

8. The universal driving apparatus of claim 2 ,

wherein the plurality of links includes a first link, a first end of which is connected to the rotation axis of the sun gear and a second link, a first end of which is connected to a second end of the first link, and

wherein rotation axes of a series of gears configured to transmit power from the sun gear to the ring gear are provided on the first link and the second link.

9. The universal driving apparatus of claim 8 , wherein, among the series of gears configured to form each of the at least one gear train, gears located at even-numbered positions from the sun gear have a same number of gear teeth as the sun gear.

10. The universal driving apparatus of claim 9 ,

wherein a gear located at a second position from the sun gear, among the gears located at even-numbered positions is a joint pinion provided concentrically with rotation axes of the first link and the second link, and

wherein a gear located at a fourth position from the sun gear among the gears located at even-numbered positions is a final pinion engaged with the ring gear.

11. The universal driving apparatus of claim 10 ,

wherein the series of gears further includes a first intermediate pinion and a second intermediate pinion,

wherein the first intermediate pinion, a rotation axis of which is provided on the first link, is engaged with the sun gear and the joint pinion, and

wherein the second intermediate pinion, a rotation axis of which is provided on the second link, is engaged with the joint pinion and the final pinion.

12. The universal driving apparatus of claim 10 ,

wherein the at least one gear train includes a plurality of gear trains provided in a circumferential direction of the sun gear, and

wherein respective final pinions of the gear trains are supported by a carrier so that relative positions of the final pinions to one another remain constant and rotation of the final pinions about rotation axes thereof is allowed.

13. The universal driving apparatus of claim 2 ,

wherein each of the at least one gear train is formed by consecutively engaging at least four gears, and

wherein rotation axes of the at least four gears are rotatably supported by the plurality of links consecutively connected.

14. The universal driving apparatus of claim 13 , wherein the at least one gear train is configured so that relative phases of the sun gear and the ring gear remain constant in response to the relative motion between the rotation axes of the sun gear and the ring gear.

15. The universal driving apparatus of claim 13 , wherein

among the at least four gears, a final pinion engaged with the ring gear is supported by a carrier so that revolution of the final pinion around the sun gear is restrained and rotation of the final pinion about a rotation axis thereof is allowed; and

the at least one balance gear is rotatably supported by the carrier.

16. The universal driving apparatus of claim 1 , wherein the at least one balance gear is provided at a position configured not to interfere with the at least one gear train and a plurality of links, during the relative motion between the rotation axes of the sun gear and the ring gear.

17. The universal driving apparatus of claim 16 , wherein the at least one balance gear is provided at a position including an angle configured to be an integer multiple of a Least Mesh Angle (LMA) of a double-pinion planetary gear set.

18. The universal driving apparatus of claim 16 , wherein the at least one balance gear includes a plurality of balance gears provided to be symmetric about the rotation axis of the ring gear.

19. The universal driving apparatus of claim 16 , wherein the at least one balance gear includes a plurality of balance gears provided to be symmetric with respect to a straight line passing through the rotation axis of the ring gear in a radial direction of the rotation axis.

20. The universal driving apparatus of claim 16 ,

wherein the at least one balance gear is rotatably supported by a carrier,

wherein among gears forming each of at least one gear train, a rotation axis of a final pinion engaged with the ring gear is rotatably supported by the carrier,

wherein the carrier is supported by a vehicle body to be raisable and lowerable,

wherein a wheel is connected to the ring gear, and

wherein a rotation axis of a motor mounted in the vehicle body is connected to the sun gear.