Electric power steering apparatus
First Claim
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1. An electric power steering apparatus for applying rotation force of a motor to a steering system including a steering member and steering wheels for performing a steering assist, the power steering apparatus comprising:
- an input shaft coupled to the steering member;
an output shaft;
a torsion bar coupling the input shaft to the output shaft;
an input shaft rotation detection unit for outputting a signal in response to rotation of the input shaft;
an output shaft rotation detection unit for outputting a signal in response to rotation of the output shaft;
a computation unit for obtaining information concerning torque transmitted between the input and output shafts and angular displacement with respect to each of the input and output shafts on the basis of outputs of the input shaft rotation detection unit and the output shaft rotation detection unit; and
a driving control unit for generating a steering assist force by driving the motor in response to the torque transmitted between the input and output shafts, wherein the driving control unit determines which of the input shaft and the output shaft is dynamically superior based on the obtained information and when the output shaft is dynamically superior to the input shaft, the driving control unit controls the motor to apply a torque that is smaller than the torque that is transmitted between the input and output shafts in a backward assist direction.
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Abstract
A driving control unit (21b) of a controller (21) determines which of an input shaft (32) and an output shaft (33) in a steering shaft (3) is dynamically superior and when the output shaft (33) is dynamically superior to the input shaft (32), a motor (6) is driven so that torque resulting in a time integral value smaller than a time integral value of relative torque between the input shaft (32) and the output shaft (33) is generated in a backward assist direction.
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Citations
16 Claims
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1. An electric power steering apparatus for applying rotation force of a motor to a steering system including a steering member and steering wheels for performing a steering assist, the power steering apparatus comprising:
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an input shaft coupled to the steering member; an output shaft; a torsion bar coupling the input shaft to the output shaft; an input shaft rotation detection unit for outputting a signal in response to rotation of the input shaft; an output shaft rotation detection unit for outputting a signal in response to rotation of the output shaft; a computation unit for obtaining information concerning torque transmitted between the input and output shafts and angular displacement with respect to each of the input and output shafts on the basis of outputs of the input shaft rotation detection unit and the output shaft rotation detection unit; and a driving control unit for generating a steering assist force by driving the motor in response to the torque transmitted between the input and output shafts, wherein the driving control unit determines which of the input shaft and the output shaft is dynamically superior based on the obtained information and when the output shaft is dynamically superior to the input shaft, the driving control unit controls the motor to apply a torque that is smaller than the torque that is transmitted between the input and output shafts in a backward assist direction. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An electric power steering apparatus comprising:
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an input shaft; an output shaft; a torsion bar coupling the input shaft to the output shaft; an input shaft rotation detector that outputs an input shaft rotation signal; an output shaft rotation detector that outputs an output shaft rotation signal; a processor that calculates angular displacement signals for each of the input shaft and the output shaft and a torque signal that represents the torque between the input shaft and the output shaft based upon the input shaft rotation signal and the output shaft rotation signal; and a driving controller that determines which of the input shaft and the output shaft is dynamically superior based on the torque signal and the angular displacement signals, and that controls a steering assist motor so that the steering assist motor applies a torque that is smaller than the torque transmitted between the input shaft and the output shaft in a backward assist direction when the output shaft is dynamically superior to the input shaft. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification