Power transmission device and automobile including the same
Disclosed is a power transmission device including a motor including a rotary shaft, a speed reducer provided on one side of the motor, and a power transmitter, provided inside the speed reducer, that transmits rotational force generated by driving of the motor to the speed reducer. The power transmitter transmits the power such that a ratio of rotational angular velocity of the speed reducer to rotational angular velocity of the rotary shaft is changed according to rotation directions of the rotary shaft of the motor.
1. A power transmission device comprising:
a motor comprising a rotary shaft;
a speed reducer provided on one side of the motor; and
a power transmitter, provided inside the speed reducer, configured to transmit rotational force generated by driving of the motor to the speed reducer,
wherein the power transmitter is configured to transmit the power such that a ratio of rotational angular velocity of the speed reducer to rotational angular velocity of the rotary shaft is changed according to rotation directions of the rotary shaft of the motor,
wherein the speed reducer comprises:
a sun gear provided on the outside of the rotary shaft of the motor in a radial direction (R);
a plurality of planetary gears provided on the outside of the sun gear in the radial direction (R) configured to engage with the sun gear; and
a carrier coupled to the plurality of planetary gears and configured to rotate in engagement with revolution of the plurality of planetary gears around the sun gear, and
wherein the power transmission unit further comprises:
a first one-way clutch provided between the rotary shaft of the motor and the sun gear, and
a second one-way clutch provided between the rotary shaft of the motor and the carrier.
2. The power transmission device of claim 1 , wherein the first one-way clutch and the second one-way clutch have phases opposite to each other.
3. The power transmission device of claim 1 , wherein when the rotary shaft of the motor rotates in a first direction (D 1 ),
the first one-way clutch is configured to transmit power to the sun gear, wherein the power is generated by rotation of the rotary shaft of the motor.
4. The power transmission device of claim 3 , wherein when the rotary shaft of the motor rotates in the first direction (D 1 ), the second one-way clutch is configured to interrupt the power transmission between the motor and the carrier.
5. The power transmission device of claim 1 , wherein when the rotary shaft of the motor rotates in a second direction (D 2 ) opposite to the first direction (D 1 ), the second one-way clutch is configured to transmit power to the carrier, wherein the power is generated by rotation of the rotary shaft of the motor.
6. The power transmission device of claim 1 , wherein the first one-way clutch and the second one-way clutch are spaced apart from each other in an axial direction (A) in which the rotary shaft extends.
7. The power transmission device of claim 1 , wherein an outer diameter of the first one-way clutch is equal to an outer diameter of the second one-way clutch.
8. The power transmission device of claim 1 , wherein the speed reducer further comprises a ring gear provided on the outside of the plurality of planetary gears in the radial direction (R) to engage with the plurality of planetary gears.
9. The power transmission device of claim 1 , further comprising a speed reducer housing configured to accommodate the speed reducer,
wherein the power transmitter further comprises a third one-way clutch provided between the carrier and the speed reducer housing.
10. The power transmission device of claim 9 , wherein the third one-way clutch has the same phase as the first one-way clutch.
11. An automobile comprising:
a power transmission device; and
a wheel configured to receive rotational force from the power transmission device,
wherein the power transmission device comprises:
a motor comprising a rotary shaft;
a speed reducer provided on one side of the motor; and
a power transmitter, provided inside the speed reducer, configured to transmit rotational force generated by driving of the motor to the speed reducer,
wherein the power transmitter is configured to transmit the power such that a ratio of rotational angular velocity of the speed reducer to rotational angular velocity of the rotary shaft is changed according to rotation directions of the rotary shaft of the motor,
wherein the speed reducer comprises:
a sun gear provided on the outside of the rotary shaft of the motor in a radial direction (R);
a plurality of planetary gears provided on the outside of the sun gear in the radial direction (R) to engage with the sun gear; and
a ring gear provided on the outside of the plurality of planetary gears in the radial direction (R) to engage with the plurality of planetary gears, and
wherein the automobile further comprises a wheel bearing coupled to the outside of the ring gear in the radial direction (R).
12. The automobile of claim 11 , wherein the speed reducer comprises:
a carrier which is coupled to the plurality of planetary gears and configured to rotate in engagement with revolution of the plurality of planetary gears around the sun gear.
13. The automobile of claim 12 ,
wherein the wheel bearing comprises:
an inner race fixed to the ring gear; and
an outer race provided on the outside of the inner race in the radial direction (R).