Hollow shaft motor

1. A hollow shaft motor, comprising:

a housing ( 11 ) having a cylindrical shape;

an upper cover ( 12 ) coupled to an upper portion of the housing ( 11 );

a lower cover ( 15 ) coupled to a lower portion of the housing ( 11 );

a stator assembly ( 20 ) located in the housing ( 11 );

a rotor assembly ( 30 ) located in the stator assembly ( 20 ) to rotate, wherein the rotor assembly ( 30 ) comprises a hollow shaft ( 31 ), a rotor core ( 32 ) coupled to an outer circumference of the hollow shaft ( 31 ), and a plurality of magnets ( 33 ) attached to an outer circumference of the rotor core ( 32 ); and

a lower bearing ( 14 ) located in the housing ( 11 ),

wherein the housing ( 11 ) has a lower protruding part ( 115 ) being formed with bent and folded to reinforce strength by a pressing process, wherein a bent portion of the lower protruding part ( 115 ) is folded by directly contacting with each other,

wherein the lower bearing ( 14 ) is supported by a support structure including a stopper ( 16 ) and a lower bearing receiving part ( 117 ), the stopper ( 16 ) located in the lower protruding part ( 115 ) and the lower bearing receiving part ( 117 ) formed such that a material of the lower protruding part ( 115 ) is bent by the pressing process to extend upwardly from a lower portion of the lower protruding part ( 115 ),

wherein the lower protruding part ( 115 ) is located in a space formed between an outer circumferential surface of the stopper ( 16 ) and in inner circumferential surface of the lower cover ( 15 ),

wherein the stopper ( 16 ) supports a lower surface of lower bearing ( 14 ) and is coupled to an inner circumferential surface of the lower protruding part ( 115 ).

2. The hollow shaft motor of claim 1 , wherein the hollow shaft ( 31 ) comprises a yoke coupling part ( 311 ) having a cylindrical shape, an upper bearing support part ( 312 ) having a diameter greater than that of the yoke coupling part ( 311 ), an upper bearing receiving part ( 313 ) having a shape bent inwardly in a lower portion of the upper bearing support part ( 312 ), and a lower bearing support part ( 316 ) protruding downwardly from the yoke coupling part ( 311 ).

3. The hollow shaft motor of claim 2 , wherein a lower sleeve ( 12 D) extending downwardly from a central portion of the upper cover ( 12 ) is formed, and the lower sleeve ( 12 D) extends inside the yoke coupling part ( 311 ).

4. The hollow shaft motor of claim 3 , wherein an upper bearing ( 13 ) is coupled to an upper side of the lower sleeve ( 12 D), and an outer race of the upper bearing ( 13 ) supports the rotation of the upper bearing support part ( 312 ).

5. The hollow shaft motor of claim 1 , wherein the lower protruding part ( 115 ) protruding downwardly is formed in a lower central portion of the housing, a space in the center of the lower protruding part ( 115 ) forms a lower opening part ( 116 ).

6. The hollow shaft motor of claim 5 , wherein an upper portion of the lower bearing ( 14 ) is received in the lower bearing receiving part ( 117 ), an outer circumference of the lower bearing ( 14 ) is press-fitted into an inner side of the lower protruding part ( 115 ), and the lower bearing ( 14 ) supports the rotation of the hollow shaft ( 31 ).

7. The hollow shaft motor of claim 6 , further comprising a lower cover ( 15 ) coupled to an outer circumferential surface of the lower protruding part ( 115 ).

8. The hollow shaft motor of claim 7 , wherein the stopper ( 16 ) is inserted into a space between the lower bearing ( 14 ) and the lower cover ( 15 ) to support the axial load of the lower bearing ( 14 ).

9. The hollow shaft motor of claim 8 , wherein the stopper ( 16 ) is integrally formed with the lower cover ( 15 ).