ELECTRIC POWER STEERING APPARATUS
First Claim
1. An electric power steering apparatus comprising:
- a steering torque detection part which detects steering torque inputted to a steering mechanism;
a current command value calculation part which calculates a current command value on the basis of at least the steering torque detected by the steering torque detection part;
an electric motor which generates a steering assist torque applied on a steering shaft of the steering mechanism; and
a motor control part which controls the electric motor by a pulse-width modulating signal on the basis of the current command value,wherein the motor control part comprises;
a motor torque detection part which detects a motor torque generated between the electric motor and the steering shaft;
a motor torque change rate detection part which calculates a change rate of the motor torque detected by the motor torque detection part; and
a duty ratio limiting part which judges that a duty ratio limiting condition is satisfied when the change rate of the motor torque calculated by the motor torque change rate detection part is not less than a threshold value for judging a steering limit, andwherein the duty ratio limiting part fixes a duty ratio of the pulse-width modulating signal to a predetermined value for limiting a torque transmitted to a torque transmitting member between the steering shaft of the steering mechanism and a steering road wheel when the duty ratio limiting condition is satisfied.
1 Assignment
0 Petitions
Accused Products
Abstract
There is provided an electric power steering apparatus having an electric motor 12 for generating a steering assist torque to a steering mechanism and a motor control part 24 for controlling the electric motor 12 by a pulse-width modulating signal in accordance with a current command value corresponding to a steering torque. The motor control part 24 has a motor torque detection part 67 detecting a motor torque, a motor torque change rate detection part 68 calculating a motor torque change rate, and a duty ratio limiting part 64 fixing a duty ratio of the pulse-width modulating signal to a predetermined value for limiting a torque transmitted to a torque transmitting member disposed between a steering shaft of a steering mechanism and a steering road wheel when a calculated torque change rate is not less than a threshold value for judging a steering limit position.
37 Citations
41 Claims
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1. An electric power steering apparatus comprising:
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a steering torque detection part which detects steering torque inputted to a steering mechanism; a current command value calculation part which calculates a current command value on the basis of at least the steering torque detected by the steering torque detection part; an electric motor which generates a steering assist torque applied on a steering shaft of the steering mechanism; and a motor control part which controls the electric motor by a pulse-width modulating signal on the basis of the current command value, wherein the motor control part comprises; a motor torque detection part which detects a motor torque generated between the electric motor and the steering shaft; a motor torque change rate detection part which calculates a change rate of the motor torque detected by the motor torque detection part; and a duty ratio limiting part which judges that a duty ratio limiting condition is satisfied when the change rate of the motor torque calculated by the motor torque change rate detection part is not less than a threshold value for judging a steering limit, and wherein the duty ratio limiting part fixes a duty ratio of the pulse-width modulating signal to a predetermined value for limiting a torque transmitted to a torque transmitting member between the steering shaft of the steering mechanism and a steering road wheel when the duty ratio limiting condition is satisfied. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An electric power steering apparatus comprising:
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a steering torque detection part which detects a steering torque inputted to a steering mechanism; a current command value calculation part which calculates a current command value on the basis of at least the steering torque detected by the steering torque detection part; an electric motor which generates a steering assist torque applied on a steering shaft of the steering mechanism; and a motor control part which controls the electric motor by a pulse-width modulating signal on the basis of the current command value, wherein the motor control part comprises; a driving current detection part which detects a driving current of the electric motor; a current change rate detection part which calculates a change rate of the driving current of the electric motor detected by the driving current section, and a duty ratio limiting part which judges that a duty ratio limiting condition is satisfied when the change rate of the driving current of the electric motor calculated by the current change rate detection part is not less than a threshold value for judging a steering limit, and wherein the duty ratio limiting part fixes a duty ratio of the pulse-width modulating signal to a predetermined value for limiting a torque transmitted to a torque transmitting member between the steering shaft of the steering mechanism and a steering road wheel when the duty ratio limiting condition is satisfied. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. An electric power steering apparatus comprising:
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a steering torque detection part which detects a steering torque inputted to a steering mechanism which steers a steering road wheel; a current command value calculation part which calculates a current command value on the basis of at least the steering torque detected by the steering torque detection part; an electric motor which generates a steering assist torque applied on a steering shaft of the steering mechanism; a motor control part which controls the electric motor by a pulse-width modulating signal on the basis of the current command value; and a self-aligning torque detection part which detects a self-aligning torque inputted to the steering shaft from the steering road wheel, wherein the motor control part comprises; a self-aligning torque change rate detection part which calculates a change rate of the self-aligning torque detected by the self-aligning torque detection part; and a duty ratio limiting part which judges that a duty ratio limiting condition is satisfied when the change rate of the self-aligning torque is not less than a threshold value for judging a steering limit, and wherein the duty ratio limiting part fixes a duty ratio of the pulse-width modulating signal to a predetermined value for limiting a torque transmitted to a torque transmitting member between the steering shaft of the steering mechanism and the steering road wheel when the duty ratio limiting condition is satisfied. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
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Specification