US4765426A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Motor driven power steering system
Assignee: Honda Motor Co Ltd
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Filing: 1987-03-31
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Granted: 1988-08-23
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Expires: 2007-03-31
Abstract
Abstract A power steering system includes an electric motor associated as an assistive power source with a steering mechanism. The steering system includes an electric power source for the motor, a motor driver connected to the electric power source for driving the motor, and a control system for controlling the motor driver. The steering system also includes a relay circuit for selectively electrically connecting and disconnecting the motor driver and the motor, thereby to effectively prevent a closed loop being formed which would otherwise provide a short circuit between the input terminals of the motor when the steering mechanism is manually operated without assistive steering power upon a failure of the power steering system.
Inventors
- 👤 Yasuo Shimizu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 19:34
CPC Classifications
B; B62; B62D; B62D5/00; B62D5/04; B62D5/0457; B62D5/0481; B62D5/0484; B62D5/0475
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
129 words
A motor-driven power steering system comprising: a steering mechanism; an electric motor operatively coupled to said steering mechanism for generating assistive steering power; a power source; motor driver means connected to said power source for driving said motor; control means for controlling said motor driver means; and switch means for selectively electrically connecting and disconnecting said motor driver means and said motor, wherein said motor driver means includes an arrangement capable of cooperating with said motor in forming a closed loop for allowing an induced current produced in said motor to flow therethrough when the steering system is subjected to a trouble, and wherein said switching means comprises a relay circuit controlled by said control means for selectively electrically connecting and disconnecting said motor driver means and said motor.
Claim 2
Dependent Claim
129 words
A motor-driven power steering system comprising: a steering mechanism; an electric motor operatively coupled to said steering mechanism for generating assistive steering power; a power source; motor driver means connected to said power source for driving said motor; control means for controlling said motor driver means; and switch means for selectively electrically connecting and disconnecting said motor driver means and said motor, wherein said motor driver means includes an arrangement capable of cooperating with said motor in forming a closed loop for allowing an induced current produced in said motor to flow therethrough when the steering system is subjected to a trouble, and wherein said switching means comprises a relay circuit controlled by said control means for selectively electrically connecting and disconnecting said motor driver means and said motor.
Claim 3
Dependent Claim
36 words
A motor-driven power steering system according to claim 1, wherein said motor driver means comprises a bridge circuit, said bridge circuit comprising two input terminals, two output terminals, and four bridge branches connected between said terminals.
Claim 4
Dependent Claim
23 words
a motor-driven power steering system according to claim 2, wherein each of said bridge branches comprises a field-effect transistor incorporating a diode therein.
Claim 5
Dependent Claim
120 words
A motor-driven power steering system according to claim 1, wherein said steering mechanism includes a steering wheel to which a steering torque can be applied, said control means comprising steering torque sensor means for issuing a signal indicative of the steering torque applied to said steering wheel, steering speed sensor means for issuing a signal indicative of the speed of rotation of said steering wheel, and current detector means for issuing a signal indicative of a current flowing through said motor, said control means being arranged such that when at least one of said signals indicates a failure as detected by said control means, said control means operates said relay circuit to electrically disconnect said motor from said motor driver.
Claim 6
Dependent Claim
28 words
A motor-driven power steering system according to claim 4, further including another switch means for selectively electrically connecting and disconnecting said power source and said motor driver means.
Claim 7
Dependent Claim
33 words
a motor-driven power steering system according to claim 2, wherein each of said bridge branches comprises a switching element controlled by said control means and a diode connected parallel to said switching element.
Claim 8
Dependent Claim
55 words
A motor-driven power steering system according to claim 2, wherein each of said bridge branches comprises an electrical combination selected from the group consisting of: (a) a combination of a switching element controlled by the control means and a diode connected parallel to the switching element and (2) a field-effect transistor incorporating a diode therein.
References Cited (Backward Citations)
JPS544309A
Cited
US4394605A
Cited
GB2132950A
Cited
US4574903A
Cited
US4557342A
Cited
US4574229A
Cited
US4645025A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-08-23 | 1992-02-22 | 1992-08-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-08-23 | 1996-02-22 | 1996-08-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-08-23 | 2000-02-22 | 2000-08-23 | $7700.00 | Window Closed / Lapsed |