Steering apparatus for automobile

• US 6,523,637 B1
• Filed: 02/06/1998
• Issued: 02/25/2003
• Est. Priority Date: 02/07/1997
• Status: Expired due to Term

• Current Assignee: Toyota Jidosha Kabushiki Kabushiki Kaisha, Koyo Seiko Co., Ltd. (Toyota Motor Corporation)
• Original Assignee: Koyo Seiko Co., Ltd. (Toyota Motor Corporation), Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Kawaguchi, Hiroshi, Nakano, Shiro, Higashira, Hideki, Takaoka, Manabu
• Primary Examiner(s): Olszewski; Robert P.
• Assistant Examiner(s): Fischer; Andrew J.
• Application Number:
  US09/020,132
• Time in Patent Office: 1,845 Days
• Field of Search: 180/402,403,405-407,446,443,422 701/41-43
• US Class Current: 180/402
• CPC Class Codes: B62D 5/003 Backup systems, e.g. for manual steering B62D5/30 takes precedence
• CPC Class Codes: B62D 5/046 Controlling the motor
• CPC Class Codes: B62D 5/0484 for reaction to failures, e.g. limp home

Abstract

A steering apparatus for automobiles having steering operating means which is not mechanically connected to a steering mechanism, a pair of steering motors provided to different positions in the steering mechanism, and a steering control unit for distributing a necessary steering force which is obtained on the basis of a deviation between an operating position of the steering operating means and an actual operating position of the steering mechanism in a prescribed ratio so as to determine target values of the outputs of the steering motors.

Claims

1. A steering apparatus for an automotive vehicle having two steerable vehicle wheels moveable to steer the vehicle, comprising:

steering operating means;

a steering mechanism which is not mechanically connected to said steering operating means and which has a shaft, which shaft is connected at either end with a respective vehicle wheel to move the steerable vehicle wheels;

a pair of steering motors which apply their outputs to the shaft at different positions along the shaft;

a first detector detecting an operating position of said steering operating means;

a second detector detecting an operating position of said shaft; and

a steering control unit calculating a necessary steering force based on a difference between the detected operating position of the steering operating means and detected operating position of the shaft and distributing the necessary steering force in a prescribed ratio between said steering motors so as to determine target values of the outputs of said steering motors,

in a normal mode of operation, both of said steering motors are driven in order to jointly produce the necessary steering force to move the pair of steerable vehicle wheels so that steering is performed according to an operation of said steering operating means.

2. A steering apparatus for an automotive vehicle having a steerable vehicle wheel moveable to steer the vehicle, comprising:

steering operating means;

a steering mechanism which is not mechanically connected to said steering operating means and which is coupled to move the steerable vehicle wheel;

a pair of steering motors which are provided to different positions in said steering mechanism and apply their outputs to said steering mechanism;

a first detector detecting an operating position of said steering operating means;

a second detector detecting an operating position of said steering mechanism; and

a steering control unit calculating a necessary steering force based on a difference between the detected operating position of the steering operating means and detected operating position of the steering mechanism and distributing the necessary steering force in a prescribed ratio between said steering motors so as to determine target values of the outputs of said steering motors,

whereby, in a normal mode of operation in which both steering motors are operative, both of said steering motors are driven in order to jointly produce the necessary steering force to move the steerable vehicle wheel so that steering is performed according to an operation of said steering operating means wherein said steering control unit includes;

a malfunction sensor actuable upon failure of said steering motors to operate; and

a fail-safe inhibitor operative upon actuation of the malfunction sensor and inhibiting the output of the steering motor on the malfunction side and changing the distribution ratio so that the output of the steering motor on the non-malfunction side is increased.

3. The steering apparatus for automobiles according to claim 2, wherein:

said steering control unit calculates a normal mode output according to the distribution ratio and a fail mode output corresponding to all of the steering force for each of said steering motors, and

said fail-safe inhibitor changing the normal mode output to the fail mode output for the steering motor on the non-malfunction side.

4. A steering apparatus for an automotive vehicle having two steerable vehicle wheels moveable to steer the vehicle by means of the movement of a shaft which extends between and is connected to the wheels, comprising:

steering operating means;

the shaft being free of a mechanical connection to said steering operating means;

a pair of steering motors which apply a moving force to the shaft at different positions along the shaft; and

a steering control unit calculating a necessary steering force based on a difference between an operating position of the steering operating means and an operating position of the shaft, the steering control unit distributing the necessary steering force between said steering motors so that the outputs of said steering motors may be different, both of said steering motors being driven in order to jointly produce the necessary steering force to move the steerable vehicle wheels so that steering is performed according to the operation of said steering operating means.