Reducer of electric power steering apparatus

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

a worm shaft bearing coupled to a worm shaft, which is tooth-engaged with a worm wheel, at an end of the worm shaft opposite to a motor shaft coupling portion;

a bearing bush fitted on an outer circumference surface of the worm shaft bearing and formed with a through-hole at a side opposite to a worm wheel side;

a damping member fitted on an outer circumference surface of the bearing bush, the damping member having an inner circumference surface on which elongated recesses are formed in an axial direction on opposite sides of the inner circumference surface such that an inner diameter may be contracted toward the worm wheel side, and an outer circumference surface which is supported on an inner surface of a gear housing;

a cover member coupled to an end of the gear housing opposite to the motor shaft coupling portion; and

a compression adjustment member coupled to the gear housing, and configured to compress the outer circumference surface of the worm shaft bearing to elastically support the worm shaft bearing toward the worm wheel so as to compensate for a clearance between the worm shaft and the worm wheel.

2. The reducer of claim 1 , wherein a plurality of axial slots are formed on the outer circumference surface of the damping member at the worm wheel side and the side opposite to the worm wheel side so as to reduce a contact area between the outer circumference surface of the damping member and an inner surface of the gear housing.

3. The reducer of claim 1 , wherein a protruding support portion inserted into and supported by an insertion recess formed in the gear housing is formed on an end of the damping member so as to prevent the damping member from being rotated about the axial direction.

4. The reducer of claim 3 , wherein a protruding insertion portion inserted into and supported by the insertion recess formed in the gear housing is further foinied on the outer circumference of the cover member.

5. A reducer of claim 1 , wherein the compression adjustment member includes:

a support member configured to pass through the damping member and the bearing bush to support the outer circumference surface of the worm shaft bearing;

an elastic member, one end of which is coupled to the support member; and

a hollow adjustment member coupled to the gear housing, the other end of the elastic member being supported inside the hollow adjustment member.

6. A reducer of claim 5 , wherein the elastic member is further provided with an elastic force measurement member which is come in contact with an elastic force measurement instrument so that the elastic force measurement instrument is introduced through a hollow portion of the adjustment member to measure an elastic force of the elastic member.