Electromagnetic servo drive for power steering

• US 4,855,655 A
• Filed: 07/27/1987
• Issued: 08/08/1989
• Est. Priority Date: 11/02/1984
• Status: Expired due to Term

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Shimizu, Yasuo
• Primary Examiner(s): Ro, Bentsu
• Application Number:
  US07/077,951
• Time in Patent Office: 743 Days
• Field of Search: 180/79.1, 180/6.44, 180/142, 180/143, 180/79, 318/628, 318/314, 318/2
• US Class Current: 388/820
• CPC Class Codes: B60G 17/0157 non-fluid unit, e.g. electric motor
• CPC Class Codes: B60G 21/0553 adjustable
• CPC Class Codes: B60G 21/0555 including an actuator inducing vehicle roll
• CPC Class Codes: B60G 2204/4191 Planetary or epicyclic gears
• CPC Class Codes: B62D 5/0463 calculating assisting torque from the motor based on driver input
• CPC Class Codes: Y10S 388/93 Load or torque

Abstract

An electromagnetic servo device (200) includes a driving control circuit (100), for an electric motor (20) for producing auxiliary torque to be applied to an output shaft (4). A control signal (Va) is provided to thereby supply an armature current (Io) of a controlled quantity, in a controlled direction of conduction thereof, in accordance with a detection signal (Vr, Vl) from a detection mechanism (13). The detection mechanism detects a phase difference (dP) between an input shaft (1) and the output shaft (4). The rotation speed (N) of the electric motor (20) is controlled with the control signal (Va), and is proportional to the quantity of the phase difference (dP).

Claims

1. An electromagnetic servo device comprising:

an input shaft;

an output shaft;

an electric motor for producing assistive torque to be applied to said output shaft;

detecting means for detecting a phase difference between said input and output shafts and for producing a phase difference signal corresponding to the magnitude and direction of said phase difference; and

motor control means for driving said electric motor and for controlling the rotational speed of said electric motor, said motor control means comprising,

a first circuit means, coupled to said detecting means for producing a phase difference magnitude signal and a phase difference direction signal corresponding to the magnitude and direction of said phase difference detected by said detecting means,

feedback circuit means for generating a rotational speed feedback signal corresponding to the rotational speed of said motor, said rotational speed feedback signal being generated by subtracting an armature current signal corresponding to the armature current from a voltage signal corresponding to the armature voltage and for feeding back said rotational speed feedback signal for combination with said phase difference magnitude signal,

a second circuit means, coupled to said first circuit means, said feedback circuit means, and said electric motor, for receiving said phase difference magnitude and direction signals and said rotational speed feedback signal, and for producing a driving pulse for said electric motor, said driving pulse having a voltage polarity which is a function of said phase difference direction signal and a mean voltage level which is a function of the combination of said phase difference magnitude signal and said rotational speed feedback signal.

2. An electromagnetic servo device according to claim 1, further comprising

a speed reducing mechanism for transmitting motor torque of said electric motor to said output shaft, in a speed reducing manner.