In-wheel motor powertrain

1. An in-wheel motor powertrain comprising:

an input gear directly connected to a motor;

an output gear disposed in parallel to the input gear;

at least one intermediate gear including a first gear and a second gear integrally and concentrically coupled to the first gear, the first gear being meshed with the input gear, and the second gear being meshed with the output gear having a pitch circle diameter different from that of the first gear; and

a planetary reduction mechanism including three rotating elements,

wherein one of the three rotating elements is concentrically connected to the output gear and another of the three rotating elements is connected to a wheel hub.

2. The in-wheel motor powertrain of claim 1 , wherein the first gear has the pitch circle diameter larger than that of the input gear, and the second gear has the pitch circle diameter smaller than those of the first gear and the output gear.

3. The in-wheel motor powertrain of claim 2 , wherein the at least one intermediate gear includes two or more intermediate gears that are installed in parallel between the input gear and the output gear.

4. The in-wheel motor powertrain of claim 1 , wherein the planetary reduction mechanism is a single-pinion simple planetary gear device comprising a sun gear connected concentrically to the output gear, a ring gear fixed to a housing, and a carrier connected to the wheel hub.

5. The in-wheel motor powertrain of claim 4 , wherein the housing is disposed to surround and support the input gear, the at least one intermediate gear, and the output gear, the wheel hub is rotatably supported on an outer circumferential surface of the housing, and the planetary reduction mechanism is positioned to surround an end of the housing on an opposite side of the output gear from the wheel hub.

6. The in-wheel motor powertrain of claim 1 , wherein a pump gear meshes with the input gear and a lubrication pump is connected to the pump gear.

7. The in-wheel motor powertrain of claim 6 , wherein the output gear is disposed on a first side of the input gear, the pump gear is disposed on a second side of the input gear, and the least one intermediate gear is disposed on a side of the input gear from the output gear.

8. The in-wheel motor powertrain of claim 5 , wherein the motor is coupled to the housing at a position on an opposite side of the planetary reduction mechanism from the housing so that the motor is configured to be separated from the housing and the input gear.

9. The in-wheel motor powertrain of claim 7 , wherein a rotation shaft of the motor passes through the housing and is coupled to the input gear inside the housing by a spline.