Method of driving stepping motor

• US 5,627,443 A
• Filed: 03/31/1995
• Issued: 05/06/1997
• Est. Priority Date: 04/06/1994
• Status: Expired due to Fees

• Current Assignee: Unisia Jecs Corporation (Hitachi, Ltd.)
• Original Assignee: Unisia Jecs Corporation (Hitachi, Ltd.)
• Inventors: Emura, Junichi, Kimura, Makoto, Sasaki, Mitsuo, Kakizaki, Shinobu
• Primary Examiner(s): IP, SHIK LUEN PAUL
• Application Number:
  US08/414,426
• Time in Patent Office: 767 Days
• Field of Search: 318/560-696, 364/424.05, 364/424.01, 364/426.01, 364/508, 280/840, 280/707, 280/714, 280/709, 280/712, 267/64.11, 188/299
• US Class Current: 318/696
• CPC Class Codes: H02P 8/18 Shaping of pulses, e.g. to reduce torque ripple
• CPC Class Codes: H02P 8/32 Reducing overshoot or oscillation, e.g. damping

Abstract

A method of driving a stepping motor comprises dividing a drive signal for each drive step into a plurality of portions in the direction of a time axis, and controlling the drive signal in connection with the plurality of portions thereof in a way of PWM so as to obtain a pattern of a gradual change in a on-duty ratio of the drive signal.

Claims

1. A method of driving a stepping motor for driving means for varying a damping-force characteristic of a shock absorber, the stepping motor having a plurality of drive steps, the method comprising the steps of:

dividing a drive signal for each drive step of the stepping motor into a plurality of portions in a direction of a time axis;

controlling each portion of said drive signal in a way of PWM so as to obtain a pattern of a gradual change in an on-duty ratio of said each portion of said drive signal, said pattern being dependent on a voltage supplied to the stepping motor; and

supplying said each portion of said drive signal as controlled to the stepping motor.

2. In a motor vehicle:

a shock absorber including means for varying a damping force characteristic;

a stepping motor mounted to said shock absorber, said stepping motor serving to drive said damping-force characteristic varying means of said shock absorber, said stepping motor having a plurality of drive steps; and

a control unit connected to said stepping motor, said control unit comprising;

means for dividing a drive signal for each drive step of said stepping motor into a plurality of portions in a direction of a time axis;

means for controlling each portion of said drive signal in a way of PWM so as to obtain a pattern of a gradual change in an on-duty ratio of said each portion of said drive signal, said pattern being dependent on a voltage supplied to said stepping motor; and

means for supplying each portion of said drive signal as controlled to said stepping motor.

3. A system for driving a stepping motor for driving means for varying a damping-force characteristic of a shock absorber, the stepping motor having a plurality of drive steps, the system comprising:

means for dividing a drive signal for each drive step of the stepping motor into a plurality of portions in a direction of a time axis;

means for controlling each portion of said drive signal in a way of PWM so as to obtain a pattern of a gradual change in an on-duty ratio of said each portion of said drive signal, said pattern being dependent on a voltage supplied to the stepping motor; and

means for supplying said each portion of said drive signal as controlled to the stepping motor.