Clearance adjusting decelerator and electric power steering apparatus having the same

1. A clearance adjusting decelerator, comprising:

a rotary housing including a worm/motor housing having a worm therein and a worm wheel housing having both sides open and having a worm wheel therein, the rotary housing being rotatable about a worm wheel housing pivot center axis;

a first worm wheel housing cap including a first cap tooth formed on one side surface and a first body integrally formed with the first cap tooth, the first body having a first inserting hole, formed on a center portion, to have a shaft pass in it and at least one first assembly hole formed on a rim thereof, wherein a worm wheel center axis passing through a center of the first inserting hole is spaced apart from the worm wheel housing pivot center axis;

a second worm wheel housing cap including a second cap tooth formed on one side surface and a second body integrally formed with the second cap tooth, the second body having a second inserting hole, formed on a center portion, to have the shaft pass in it and at least one second assembly hole formed on a rim thereof, wherein a worm wheel center axis passing through a center of the second inserting hole is spaced apart from the worm wheel housing pivot center axis;

at least one fastening member passing through at least one first assembly hole formed on the first worm wheel housing cap and at least one second assembly hole formed on the second worm wheel housing cap; and

wherein clearance between the worm and the worm wheel is adjusted by rotating the rotary housing relative to the worm wheel housing pivot center axis.

2. The clearance adjusting decelerator as claimed in claim 1 , wherein both sides of the worm wheel housing includes a housing tooth, respectively, so that the housing tooth is fitted to the cap tooth.

3. The clearance adjusting decelerator as claimed in claim 1 , wherein the worm wheel center axis passing through the first inserting hole and the second inserting hole is spaced apart from the worm wheel housing pivot center axis by a range of 3˜7 mm.

4. The clearance adjusting decelerator as claimed in claim 1 , wherein a pivot angle(θ) by which the rotary housing rotates relative to the worm wheel housing pivot center axis is a range of 2°˜7°.

5. The clearance adjusting decelerator as claimed in claim 1 , wherein the fastening member includes a screw.

6. An electric power steering apparatus, comprising:

a worm wheel connected to a steering shaft;

a worm engaged with the worm wheel;

a motor for providing a rotational force to the worm; and

a gear housing enclosing the worm wheel, the worm and the motor,

wherein the gear housing comprises:

a rotary housing including a worm/motor housing having the worm therein and a worm wheel housing having both sides open and having a worm wheel therein, the rotary housing being rotatable about a worm wheel housing pivot center axis;

a first worm wheel housing cap including a first cap tooth formed on one side surface and a first body integrally formed with the first cap tooth, the first body having a first inserting hole, formed on a center portion, to have the steering shaft pass in it and at least one first assembly hole formed on a rim thereof, wherein a worm wheel center axis passing through a center of the first inserting hole is spaced apart from the worm wheel housing pivot center axis;

a second worm wheel housing cap including a second cap tooth formed on one side surface and a second body integrally formed with the second cap tooth, the second body having a second inserting hole, formed on a center portion, to have the steering shaft pass in it and at least one second assembly hole formed on a rim thereof, wherein a worm wheel center axis passing through a center of the second inserting hole is spaced apart from the worm wheel housing pivot center axis;

at least one fastening member passing through at least one first assembly hole formed on the first worm wheel housing cap and at least one second assembly hole formed on the second worm wheel housing cap; and

wherein clearance between the worm and the worm wheel is adjusted by rotating the rotary housing relative to the worm wheel housing pivot center axis.

7. A clearance adjusting speed reducer, comprising:

a worm/motor housing surrounding a worm;

a worm wheel housing surrounding a worm wheel and having both sides open;

a rotary housing having the worm/motor housing and the worm wheel housing, the rotary housing being rotatable about a worm wheel housing pivot center axis;

a first worm wheel housing cap including a first body having a first inserting hole, formed on a center portion, to have a shaft pass through it, wherein a worm wheel center axis passing through a center of the first inserting hole is spaced apart from the worm wheel housing pivot center axis; and

a second worm wheel housing cap including a second body having a second inserting hole, formed on a center portion, to have the shaft pass through it, wherein the worm wheel center axis passing through a center of the second inserting hole is spaced apart from the worm wheel housing pivot center axis,

wherein clearance between the worm and the worm wheel is adjusted by rotating the rotary housing relative to the worm wheel housing pivot center axis.