Steering apparatus for vehicle

A steering apparatus for a vehicle, the apparatus comprising:

• at least one of an electric telescopic mechanism driving a steering wheel provided at a steering shaft such that the steering wheel moves in a front and rear direction relative to a vehicle body, and an electric tilt mechanism driving the steering wheel in an upper and lower direction;
• the one of the electric telescopic mechanism and the electric tilt mechanism including:
• an electric motor supported by the steering shaft;
• a threaded shaft connected to an output shaft of the electric motor;
• a speed reduction mechanism decelerating rotation of the threaded shaft relative to rotation of the output shaft;
• and
• the speed reduction mechanism including:
• a worm gear provided at the output shaft;
• a screw gear provided at the threaded shaft;
• an idle gear including a screw tooth meshing with the screw gear and the worm gear;
• and
• the output shaft and the threaded shaft being connected to each other via the idle gear such that at least one of a relationship of parallelism, a relationship of inclination and a relationship of skew is established between the output shaft and the threaded shaft wherein
• at the speed reduction mechanism, the idle gear includes a helix angle corresponding to A, the screw gear includes a helix angle corresponding to B, and the worm gear includes a lead angle corresponding to C, and
• the speed reduction mechanism is configured such that A+2×B+C=90 degrees or A+2×B−C=90 degrees is satisfied.