| 摘要 |
PROBLEM TO BE SOLVED: To provide a transmission ratio variable steering device preventing switching noise generated from a switching transistor from making an occupant uncomfortable while restraining heat generation of the switching transistor. SOLUTION: A microcomputer 31 is provided with a frequency varying means 311 varying the frequency of a PWM driving signal driving the switching transistor 324 to fall within an audible frequency region (low frequency) when an engine speed EG is more than a prescribed engine speed, and varying the frequency of the PWM driving signal driving the switching transistor 324 to be the frequency higher than audible frequency out of the audible frequency region (high frequency) when the engine speed EG is less than the prescribed engine speed. COPYRIGHT: (C)2005,JPO&NCIPI |
