EP0706930A2
Expired / Lapsed
EP
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Electric power steering apparatus
Assignee: Koyo Seiko Co Ltd
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Filing: 1995-10-12
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Granted: —
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Expires: 2015-10-12
Abstract
Abstract In an electric power steering apparatus, a motor current target value of a steering force assisting motor is determined on the basis of a torque detected by a torque sensor, the drive of the motor is controlled with using the motor current target value as a target value of an automatic control, and the driving current of the motor as the feedback value of the automatic control, and, when the detected torque is within a predetermined range, the motor is inhibited from being driven in the direction opposite to the detected torque. The electric power steering apparatus has a motor non-drive detecting circuit for detecting that the motor current target value is zero, and a drive inhibition holding circuit for holding the motor drive inhibition state where the motor is inhibited from being driven in the direction opposite to the detected torque, until the motor non-drive detecting circuit detects that the motor current target value is zero. Even when a CPU runs away and the motor current target value becomes excessive, self-rotation of a steering wheel and reverse assist caused by the flow of the excess motor current are prevented from occurring. Even when a CPU runs away and the assist and the assist inhibition are repeated, furthermore, the steering is prevented from becoming unstable.
Inventors
- 👤 Mitsuhiko c/o Koyo Seiko Co. Ltd. Nishimoto
- 👤 c/o Koyo Seiko Co. Ltd. Higashira Hideki
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-26 03:21
CPC Classifications
B; B62; B62D; B62D5/00; B62D5/04; B62D5/0457; B62D5/046; B62D5/0463; B62D5/0481; B62D5/0493
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
163 words
An electric power steering apparatus in which a motor current target value of a steering force assisting motor (4) is determined on the basis of a torque detected by a torque sensor (1), a drive of said motor (4) is controlled with using the motor current target value as a target value of an automatic control, and a driving current of said motor (4) as a feedback value of the automatic control, and, when the detected torque is within a predetermined range, said motor (4) is inhibited from being driven in a direction opposite to the detected torque, characterized in that said apparatus comprises non-drive detecting means (11) for detecting that the motor current target value is zero, and drive inhibition holding means (13) for holding the motor drive inhibition state where said motor (4) is inhibited from being driven in the direction opposite to the detected torque, until said non-drive detecting means (11) detects that the motor current target value is zero.
Claim 2
Dependent Claim
105 words
An electric power steering apparatus according to claim 1, wherein said apparatus further comprises dead zone detecting means (10) for detecting a dead zone of the detected torque where the motor current target value is to be zero, and abnormal state detecting means (9) for detecting a state where the detected torque is outside the dead zone and the direction in which said motor (4) is to be driven in accordance with the motor current target value is opposite to the direction of the detected torque, and, when said abnormal state detecting means (9) detects the state, said motor (4) is inhibited from being driven.
Claim 3
Dependent Claim
90 words
An electric power steering apparatus according to claim 1, wherein said apparatus further comprises dead zone detecting means (10) for detecting a dead zone of the detected torque where the motor current target value is to be zero, and abnormal state detecting means (6) for detecting a state where the detected torque is inside the dead zone and the driving current of said motor (4) is greater than a predetermined value, and, when said abnormal state detecting means (6) detects the state, said motor (4) is inhibited from being driven.
Claim 4
Dependent Claim
141 words
An electric power steering apparatus according to claim 1, wherein said apparatus further comprises: dead zone detecting means (10) for detecting a dead zone of the detected torque where the motor current target value is to be zero; first abnormal state detecting means (9) for detecting a first state where the detected torque is outside the dead zone and the direction in which said motor (4) is to be driven in accordance with the motor current target value is opposite to the direction of the detected torque; and second abnormal state detecting means (6) for detecting a second state where the detected torque is inside the dead zone and the driving current of said motor (4) is greater than a predetermined value, and, when the first state or the second state is detected, said motor (4) is inhibited from being driven.
Claim 5
Dependent Claim
80 words
An electric power steering apparatus according to claim 4, wherein said apparatus further comprises a first timer (12) which, when the first state or the second state is detected, starts a timer operation for a first predetermined time (T1), and which, when the first state or the second state is not detected any longer, is reset, and, when said first timer (12) completes the timer operation for the first predetermined time (T1), said motor (4) is inhibited from being driven.
Claim 6
Dependent Claim
146 words
An electric power steering apparatus according to claim 5, wherein said apparatus further comprises: a second timer (15) which, when the first state or the second state is detected, starts a timer operation for a second predetermined time (T2), and which, when the first state or the second state is not detected any longer, is reset; abnormality detection signal holding means (16) for, when said second timer (15) completes the timer operation for the second predetermined time (T2), holding an abnormality detection signal from said first abnormal state detecting means (9) or said second abnormal state detecting means (6); and relay drive inhibiting means (17) for, during a period when said abnormality detection signal holding means (16) holds the abnormality detection signal, turning off a fail safe relay (18), said fail safe relay (18) connecting a drive circuit for said motor (4) with a power source.
Claim 7
Dependent Claim
149 words
An electric power steering apparatus according to claim 1, wherein said apparatus further comprises: dead zone detecting means (10) for detecting a dead zone of the detected torque where the motor current target value is to be zero; torque change direction detecting means (31) for detecting a change direction of the detected torque; and abnormal state detecting means (9a) for detecting a state where the detected torque is outside the dead zone, the direction in which said motor (4) is to be driven in accordance with the motor current target value is opposite to the direction of the detected torque, and the direction in which said motor (4) is to be driven in accordance with the motor current target value is opposite to the change direction of the detected torque, and, when said abnormal state detecting means (9a) detects the state, said motor (4) is inhibited from being driven.
Claim 8
Dependent Claim
129 words
An electric power steering apparatus according to claim 1, wherein said apparatus further comprises : dead zone detecting means (10) for detecting a dead zone of the detected torque where the motor current target value is to be zero; torque change direction detecting means (31) for detecting a change direction of the detected torque; and abnormal state detecting means (6a) for detecting a state where the detected torque is inside the dead zone, the driving current of said motor (4) is greater than a predetermined value, and the direction in which said motor (4) is driven by the driving current is opposite to the change direction of the detected torque, and, when said abnormal state detecting means (6a) detects the state, said motor (4) is inhibited from being driven.
Claim 9
Dependent Claim
208 words
An electric power steering apparatus according to claim 1, wherein said apparatus further comprises: dead zone detecting means (10) for detecting a dead zone of the detected torque where the motor current target value is to be zero; torque change direction detecting means (31) for detecting a change direction of the detected torque; third abnormal state detecting means (9a) for detecting a third state where the detected torque is outside the dead zone, the direction in which said motor (4) is to be driven in accordance with the motor current target value is opposite to the direction of the detected torque, and the direction in which said motor (4) is to be driven in accordance with the motor current target value is opposite to the change direction of the detected torque; and fourth abnormal state detecting means (6a) for detecting a fourth state where the detected torque is inside the dead zone, the driving current of said motor (4) is greater than a predetermined value, and the direction in which said motor (4) is driven by the driving current is opposite to the change direction of the detected torque, and, when the third state or the fourth state is detected, said motor (4) is inhibited from being driven.
Claim 10
Dependent Claim
80 words
An electric power steering apparatus according to claim 9, wherein said apparatus further comprises a first timer (12) which, when the third state or the fourth state is detected, starts a timer operation for a first predetermined time (T1), and which, when the third state or the fourth state is not detected any longer, is reset, and, when said first timer (12) completes the timer operation for the first predetermined time (T1), said motor (4) is inhibited from being driven.
Claim 11
Dependent Claim
146 words
An electric power steering apparatus according to claim 10, wherein said apparatus further comprises: a second timer (15) which, when the third state or the fourth state is detected, starts a timer operation for a second predetermined time (T2), and which; when the third state or the fourth state is not detected any longer, is reset; abnormality detection signal holding means (16) for, when said second timer (15) completes the timer operation for the second predetermined time (T2), holding an abnormality detection signal from said third abnormal state detecting means (9a) or said fourth abnormal state detecting means (6a); and relay drive inhibiting means (17) for, during a period when said abnormality detection signal holding means (16) holds the abnormality detection signal, turning off a fail safe relay (18), said fail safe relay (18) connecting a drive circuit for said motor (4) with a power source.
Claim 12
Dependent Claim
31 words
An electric power steering apparatus according to claim 3, 4, 8, or 9, wherein the predetermined value is greater than a maximum value of a return current of a steering wheel.
Claim 13
Dependent Claim
26 words
An electric power steering apparatus according to claim 6 or 11, wherein the second predetermined time (T2) is sufficiently longer than the first predetermined time (T1).
Claim 14
Dependent Claim
60 words
An electric power steering apparatus according to claim 6 or 11, wherein said apparatus further comprises an indication lamp (19) which is lit during a period when said drive inhibition holding means (13) holds the motor drive inhibition state of said motor (4), or during a period when said abnormality detection signal holding means (16) holds the abnormality detection signal.
References Cited (Backward Citations)
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