Patent ID: 7465918

Claim:
A rotation angle sensing device comprising: a case having an opening therethrough, said opening being defined by an opening inner wall; a rotary body rotatably supported in said opening of said case and configured to be rotatable together with a steering shaft; a first detector body mounted in said case and engaged with said rotary body so as to rotate with rotation of said rotary body; a first detector device arranged to detect rotation of said first detector body and generate a first rotation detection signal; a control circuit configured to detect a rotation angle of said rotary body based on said first rotation detection signal; a plurality of protrusions formed on said opening inner wall and protruding radially inwardly from said opening inner wall into said opening of said case; and a thrusting device arranged to thrust one of said rotary body and said first detector body toward the other of said rotary body and said first detector body such that said rotary body is pressed toward and into contact against said protrusions protruding radially inwardly from said opening inner wall so that, during rotation of said rotary body relative to said case, said rotary body rotates in sliding contact with said protrusions, to prevent play and eccentricity of said rotary body during rotation thereof.