Reducer of electric power-assisted steering apparatus

1. A reducer of an electric power-assisted steering apparatus, the reducer comprising:

a worm shaft configured to mesh with a worm wheel and comprising recesses;

a worm shaft bush configured to be coupled to an outer periphery of an end of the worm shaft to be coupled with a motor shaft among opposite ends of the worm shaft, the worm shaft bush comprising ribs; and

a connection member configured to be coupled to an outer periphery of the worm shaft bush at one side thereof, and to be coupled to an outer periphery of the motor shaft at another side thereof such that a torque of the motor shaft is coaxially delivered to the worm shaft,

wherein first through-holes are formed in the ribs of the worm shaft bush, and rolling members are engaged in the first through-holes to be inserted into the recesses of the worm shaft.

2. The reducer of claim 1 , wherein the worm shaft bush is formed in a cylindrical shape and is provided with the ribs that are formed at circumferentially spaced positions to protrude toward an inner peripheral surface and an outer peripheral surface while being elongated in an axial direction, and the recesses are formed in an axial direction on the end of the worm shaft and the inner peripheral surface of the connection member such that the ribs are inserted into the recesses.

3. The reducer of claim 1 , wherein the first through-holes are formed to be spaced apart from each other in an axial direction of the ribs, and the rolling members are engaged in the first through-holes, respectively.

4. The reducer of claim 1 , further comprising second through-holes formed in the ribs of the worm shaft bush, wherein damping members are engaged in the second through-holes to be inserted into the recesses, respectively.

5. The reducer of claim 4 , wherein the damping members and the rolling members are alternately arranged in the circumferential direction.

6. The reducer of claim 5 , wherein six ribs are formed, the rolling members are coupled to three ribs, respectively, and the damping members are coupled to remaining three ribs, respectively, and the damping members and the rolling members are alternately arranged in the circumferential direction.

7. The reducer of claim 5 , wherein the connection member includes an inner member coupled to the outer periphery of the worm shaft bush, an outer member coupled to the outer periphery of the motor shaft, and an elastic member interposed between the inner member and the outer member to be in close contact with the inner and outer members.

8. The reducer of claim 7 , wherein the outer member includes a spline provided in a coupling hole to correspond to an axial spline formed on the motor shaft, the motor shaft being coupled to the coupling hole.

9. The reducer of claim 7 , wherein the rolling members are engaged in the recesses of the worm shaft and the inner member to be in point contact with the recesses, respectively, at one or more locations, and the damping members are engaged in the recesses of the worm shaft and the inner member to form gaps with the recesses, respectively.

10. A reducer of an electric power-assisted steering apparatus, the reducer comprising:

a worm shaft configured to mesh with a worm wheel and comprising recesses;

a worm shaft bush configured to be coupled to an outer periphery of an end of the worm shaft to be coupled with a motor shaft among opposite ends of the worm shaft, the worm shaft bush comprising ribs; and

a connection member configured to be coupled to an outer periphery of the worm shaft bush at one side thereof, and to be coupled to an outer periphery of the motor shaft at another side thereof such that a torque of the motor shaft is coaxially delivered to the worm shaft,

wherein first through-holes are formed in the ribs of the worm shaft bush, and damping members are engaged in the first through-holes to be inserted into the recesses of the worm shaft.

11. The reducer of claim 10 , wherein the worm shaft bush is formed in a cylindrical shape and is provided with the ribs that are formed at circumferentially spaced positions to protrude toward an inner peripheral surface and an outer peripheral surface while being elongated in an axial direction, and the recesses are formed in an axial direction on the end of the worm shaft and the inner peripheral surface of the connection member such that the ribs are inserted into the recesses.

12. The reducer of claim 10 , wherein the second through-holes are formed in the ribs of the worm shaft bush, and the rolling members are engaged in the second through-holes to be inserted into the recesses.

13. The reducer of claim 10 , wherein second through-holes are formed to be spaced apart from each other in an axial direction of the ribs, and rolling members are engaged in the second through-holes.

14. A reducer of an electric power-assisted steering apparatus, the reducer comprising:

a worm shaft configured to mesh with a worm wheel and comprising recesses;

a worm shaft bush configured to be coupled to an outer periphery of an end of the worm shaft to be coupled with a motor shaft among opposite ends of the worm shaft, the worm shaft bush comprising ribs; and

a connection member configured to be coupled to an outer periphery of the worm shaft bush at one side thereof, and to be coupled to an outer periphery of the motor shaft at another side thereof such that a torque of the motor shaft is coaxially delivered to the worm shaft,

wherein the connection member includes an inner member coupled to the outer periphery of the worm shaft bush, an outer member coupled to the outer periphery of the motor shaft, and an elastic member interposed between the inner member and the outer member to be in close contact with the inner and outer members.

15. The reducer of claim 14 , wherein the worm shaft bush is formed in a cylindrical shape and is provided with the ribs that are formed at circumferentially spaced positions to protrude toward an inner peripheral surface and an outer peripheral surface while being elongated in an axial direction, and the recesses are formed in an axial direction on the end of the worm shaft and the inner peripheral surface of the connection member such that the ribs are inserted into the recesses.

16. The reducer of claim 15 , wherein first through-holes are formed in the ribs of the worm shaft bush, and rolling members are engaged in the first through-holes to be inserted into the recesses of the worm shaft.

17. The reducer of claim 15 , wherein second through-holes are formed in the ribs of the worm shaft bush, and damping members are engaged in the second through-holes to be inserted into the recesses, respectively.

18. The reducer of claim 15 , wherein first through-holes are formed in the ribs of the worm shaft bush, and rolling members are engaged in the first through-holes to be inserted into the recesses of the worm shaft, second through-holes are formed in the ribs of the worm shaft bush, and damping members are engaged in the second through-holes to be inserted into the recesses, respectively, and the damping member and the rolling member are alternately arranged in the circumferential direction.

19. The reducer of claim 14 , wherein the connection member includes shapes that protrude diametrically to be orthogonal to each other from the central hole in order to prevent a rotational slip from occurring among the inner member, the outer member, and the elastic member.