Power train device for electric vehicle

1. A power train device for an electric vehicle, the power train device comprising:

a first planetary gear set including:

a first sun gear rotatably mounted on one side axle shaft,

a first planet gear configured to externally engage with the first sun gear, and

a first carrier configured to support the first planet gear;

a second planetary gear set including:

a second planet gear disposed at one side of the first planet gear, the second planet gear being supported by the first carrier together with the first planet gear, and

a first ring gear configured to externally engage with the second planet gear while surrounding the second planet gear; and

a third planetary gear set including:

a second sun gear rotatably mounted on the one side axle shaft to be opposite to the first carrier,

a third planet gear configured to externally engage with the second sun gear,

a second carrier configured to support the third planet gear, and

a second ring gear configured to externally engage with the third planet gear while surrounding the third planet gear,

wherein a sleeve is disposed between the first carrier and the second carrier, and

wherein the sleeve is configured to transmit power between the first carrier and the second sun gear while moving in a first shift position engagement direction or transmit power between the first carrier and the second carrier while moving in a second shift position engagement direction.

2. The power train device of claim 1 ,

wherein the sleeve is configured to perform a first shift position engagement operation or a second shift position engagement operation while being moved in an axial direction by a controller.

3. The power train device of claim 1 ,

wherein the sleeve is spline-coupled to a first hub disposed at one side of the first carrier, and the first hub is positioned opposite to a second hub disposed at one side of the second carrier.

4. The power train device of claim 3 ,

wherein the sleeve comprises:

a first spline defined on an outer-diameter portion of the sleeve; and

a second spline defined on an inner-diameter portion of the sleeve, and

wherein during a first shift position engagement operation of the sleeve, the first spline is configured to engage with a third spline defined on an inner-diameter portion of the first hub, and the second spline is configured to engage with a fourth spline defined at one side of the second sun gear.

5. The power train device of claim 4 ,

wherein during a second shift position engagement operation of the sleeve, the first spline is configured to engage with the third spline, and the second spline is configured to engage with a fifth spline defined on an outer-diameter portion of the second hub.

6. The power train device of claim 1 ,

wherein the second carrier is connected to a differential device.

7. The power train device of claim 6 ,

wherein the differential device comprises:

a casing connected to another side of the second carrier;

a pinion gear connected to the casing by a connection shaft in the casing, the pinion gear being rotatable about the connection shaft;

one side gear connected to the one side axle shaft while engaging with one side of the pinion gear; and

another side gear connected to another side axle shaft while engaging with another side of the pinion gear.

8. The power train device of claim 7 ,

wherein the one side axle shaft is connected to one side driving wheel, and the another side axle shaft is connected to another side driving wheel.

9. The power train device of claim 1 ,

wherein the first sun gear is connected to an input shaft of a motor.

10. The power train device of claim 9 ,

wherein the input shaft is a hollow shaft rotatably mounted on an outer-diameter portion of the one side axle shaft, the input shaft being configured to transmit power of the motor to the first sun gear.

11. The power train device of claim 1 ,

wherein the first ring gear and the second ring gear are fixed to an axle housing.