Power steering apparatus

An electric power steering apparatus, comprising:

• a steering assisting electric motor;
• a worm directly connected to an output side of said electric motor;
• an output shaft connected to a steering mechanism of a vehicle;
• a worm wheel installed coaxially with said output shaft and engaging with said worm;
• a lock nut having a nut portion that is screwed onto a threaded portion formed on an outer circumference of said output shaft, and a tapered portion formed integrally on the advancing side of said nut portion and whose outer diameter gradually decreases toward an forward end thereof;
• a tapered fitting hole which is formed through an axis of said worm wheel and to which the tapered portion of said lock nut is fitted;
• and
• a support portion for supporting said worm wheel against axial pressure being exerted thereon via fitting faces of said tapered portion and said fitting hole by the advancing motion of said lock nut.

An electric power steering apparatus, comprising:

• a steering assisting electric motor;
• a worm directly connected to an output side of said electric motor;
• an output shaft connected to a steering mechanism of a vehicle;
• a worm wheel installed coaxially with said output shaft and engaging with said worm;
• a lock nut screwed on a threaded portion on an outer circumference of said output shaft;
• a tapered ring fitted on said output shaft on the advancing side of said lock nut, and whose outer diameter gradually decreases in the advancing direction;
• tapered fitting hole which is formed through an axis of said worm wheel and to which said tapered ring is fitted;
• and
• a support portion for supporting said worm wheel against axial pressure which is exerted thereon via fitting faces of said tapered ring and said fitting hole by the advancing motion of said lock nut.

An electric power steering apparatus, comprising:

• a steering assisting electric motor;
• a worm directly connected to an output side of said electric motor;
• an output shaft connected to a steering mechanism of a vehicle;
• a worm wheel installed coaxially with said output shaft and engaging with said worm;
• a tapered portion formed on an outer circumference of said output shaft and whose diameter gradually decreases toward one end thereof in an axial direction;
• threaded portion formed integrally on the outer circumference of said output shaft on the smaller diameter side of said tapered portion;
• tapered fit, ting hole formed through an axis of said worm wheel and having a tapered shape that matches said tapered portion;
• and
• a lock nut screwed on said threaded portion,
• wherein said worm wheel is fitted on said tapered portion via said fitting hole, and is clamped in position with the pressure exerted toward the larger diameter side thereof by the tightening of said lock nut being supported by fitting faces of said tapered portion and said fitting hole.

An electric power steering apparatus, comprising:

• a steering assisting electric motor;
• a worm directly connected to an output side of said electric motor;
• an output shaft connected to a steering mechanism of a vehicle;
• and
• a worm wheel installed coaxially with said output shaft and engaging with said worm,
• wherein said worm wheel is fitted to an outer circumference of said output shaft via a plurality of rolling members arranged circumferentially, and by tightening a lock nut that is screwed onto one end of a fitting portion of said output shaft, said worm wheel is held in position between said lock nut and a support portion formed on the other end of the fitting portion.