Drum washing machine

1 . A drum washing machine comprising:

an inner tub that extends in a horizontal direction; and

a drive system coupled to the inner tub, the drive system comprising:

a housing that has an internal space and is integrally provided with the inner tub,

a motor disposed at a side of the housing,

a rotor shaft coupled to the motor and the housing,

an output shaft coupled to the housing, at least a part of the output shaft being disposed in the rotor shaft,

a planetary gear set disposed in the internal space of the housing, the planetary gear set comprising (i) a first portion coupled to the rotor shaft and (ii) a second portion coupled to the output shaft,

an actuator configured to move the planetary gear set along the horizontal direction,

a first bearing disposed in the internal space of the housing and disposed between an outer surface of the output shaft and an inner surface of the housing, and

a second bearing disposed in the internal space of the housing and disposed between an outer surface of the rotor shaft and the inner surface of the housing, the second bearing rotatably coupling the rotor shaft to the inner surface of the housing.

2 . The drum washing machine of claim 1 , wherein the inner tub is made of a plastic material, and

wherein the housing is made of a metal material and double-injected with the inner tub.

3 . The drum washing machine of claim 2 , wherein the inner tub comprises a protruding area that protrudes from a central area of a first surface of the inner tub toward a second surface opposite to the first surface, and

wherein the housing is double-injected into the protruding area.

4 . The drum washing machine of claim 1 , wherein the planetary gear set is disposed between the first bearing and the second bearing.

5 . The drum washing machine of claim 4 , wherein the inner tub comprises a protruding area that protrudes from a central area of a first surface of the inner tub toward a second surface opposite to the first surface,

wherein the first bearing overlaps with the protruding area along a vertical direction orthogonal to the horizontal direction, and

wherein the second bearing is spaced apart from the first bearing in the horizontal direction such that the second bearing does not overlap with the inner tub along the vertical direction.

6 . The drum washing machine of claim 1 , wherein an entirety of the planetary gear set overlaps with the inner tub along a vertical direction orthogonal to the horizontal direction.

7 . The drum washing machine of claim 1 , wherein the motor is spaced apart from the inner tub in the horizontal direction such that the motor does not overlap with the inner tub along a vertical direction orthogonal to the horizontal direction.

8 . The drum washing machine of claim 1 , wherein the planetary gear set comprises:

a sun gear coupled to the rotor shaft;

a plurality of pinion gears spaced apart from one another in a circumferential direction and coupled to an outer circumferential surface of the sun gear;

a ring gear having an inner circumferential surface coupled to the plurality of pinion gears; and

a carrier coupled to the plurality of pinion gears and the output shaft.

9 . The drum washing machine of claim 8 , wherein the planetary gear set is configured to:

based on the actuator moving the planetary gear set to a first side along the horizontal direction to thereby couple a part of the planetary gear set to the rotor shaft, transmit a rotational force of the rotor shaft to the output shaft with a first gear ratio; and

based on the actuator moving the planetary gear set to a second side along the horizontal direction to thereby couple another part of the planetary gear set to the housing, reduce and transmit the rotational force of the rotor shaft to the output shaft with a second gear ratio different from the first gear ratio.

10 . The drum washing machine of claim 9 , wherein the first gear ratio is 1:1, and the second gear ratio is n:1, wherein n is greater than 1.

11 . The drum washing machine of claim 8 , wherein each of the sun gear, the plurality of pinion gears, and the ring gear comprises one or more helical gears.

12 . A drum washing machine comprising:

an inner tub that extends in a horizontal direction; and

a drive system coupled to the inner tub, the drive system comprising:

a housing that has an internal space,

a motor disposed at one side of the housing,

a rotor shaft coupled to the motor and the housing,

an output shaft coupled to the housing, at least a part of the output shaft being disposed in the rotor shaft,

a planetary gear set disposed in the internal space of the housing, the planetary gear set comprising (i) a first portion coupled to the rotor shaft and (ii) a second portion coupled to the output shaft,

an actuator configured to move the planetary gear set along the horizontal direction,

a first bearing disposed in the internal space of the housing and disposed between an outer surface of the output shaft and an inner surface of the housing, and

a second bearing disposed in the internal space of the housing and disposed between an outer surface of the rotor shaft and the inner surface of the housing, the second bearing rotatably coupling the rotor shaft to the inner surface of the housing,

wherein an entirety of the planetary gear overlaps with the inner tub in a vertical direction orthogonal to the horizontal direction.

13 . The drum washing machine of claim 12 , wherein the inner tub comprises a protruding area that protrudes from a central area of a first surface of the inner tub toward a second surface opposite to the first surface, and

wherein the housing is double-injected into the protruding area.

14 . The drum washing machine of claim 12 , wherein the planetary gear set is disposed between the first bearing and the second bearing.

15 . The drum washing machine of claim 14 , wherein the inner tub comprises a protruding area that protrudes from a central area of a first surface of the inner tub toward a second surface opposite to the first surface,

wherein the first bearing overlaps with the protruding area in the vertical direction, and

wherein the second bearing is spaced apart from the first bearing in the horizontal direction such that the second bearing does not overlap with the inner tub along the vertical direction.

16 . The drum washing machine of claim 12 , wherein the motor is spaced apart from the inner tub in the horizontal direction such that the motor does not overlap with the inner tub along the vertical direction.

17 . The drum washing machine of claim 12 , wherein the planetary gear set comprises:

a sun gear coupled to the rotor shaft;

a plurality of pinion gears spaced apart from one another in a circumferential direction and coupled to an outer circumferential surface of the sun gear;

a ring gear having an inner circumferential surface coupled to the plurality of pinion gears; and

a carrier coupled to the plurality of pinion gears and the output shaft.

18 . The drum washing machine of claim 17 , wherein each of the sun gear, the plurality of pinion gears, and the ring gear comprises one or more helical gears.

19 . The drum washing machine of claim 12 , wherein the planetary gear set is configured to:

based on the actuator moving the planetary gear set to a first side along the horizontal direction to thereby couple a part of the planetary gear set to the rotor shaft, transmit a rotational force of the rotor shaft to the output shaft with a first gear ratio; and

based on the actuator moving the planetary gear set to a second side along the horizontal direction to thereby couple another part of the planetary gear set to the housing, reduce and transmit the rotational force of the rotor shaft to the output shaft with a second gear ratio different from the first gear ratio.

20 . The drum washing machine of claim 19 , wherein the first gear ratio is 1:1, and the second gear ratio is n:1, wherein n is greater than 1.