Patent US4991676A successfully refreshed from Google Patents.
US4991676A
Expired / Lapsed
US
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Motorized power steering apparatus
Assignee: Mitsubishi Electric Corp
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Filing: 1989-09-18
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Granted: 1991-02-12
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Expires: 2009-09-18
Abstract
Abstract A motorized power steering apparatus for a vehicle has a torque sensor which generates an output voltage corresponding to a steering torque exerted by the driver of the vehicle. A motor controller controls the output torque of a drive motor which generates an auxiliary steering force corresponding to the output voltage of the torque sensor. The motor controller is a self-excited pulse width modulation circuit with feedback from the motor which supplies the motor with drive pulses having a pulse width modulated by the output voltage of the torque sensor.
Inventors
- 👤 Mitsuharu Morishita
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 16:32
CPC Classifications
B; B62; B62D; B62D5/00; B62D5/04; B62D5/0457; B62D5/046; B62D5/0463
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
109 words
A motorized power steering apparatus for a vehicle comprising: torque sensing means for generating an output voltage proportional to both a supply voltage and to a steering torque exerted by a driver of the vehicle; a motor for generating an auxiliary steering force; a self-excited pulse width modulation circuit for supplying the motor with drive pulses having a pulse width which is modulated by the output voltage of the torque sensing means; and feedback means embodying RC time constant means (941-946) connected between the motor and the pulse width modulation circuit for preventing variations in the net energy applied to the motor due to variations in the supply voltage.
Claim 2
Dependent Claim
109 words
A motorized power steering apparatus for a vehicle comprising: torque sensing means for generating an output voltage proportional to both a supply voltage and to a steering torque exerted by a driver of the vehicle; a motor for generating an auxiliary steering force; a self-excited pulse width modulation circuit for supplying the motor with drive pulses having a pulse width which is modulated by the output voltage of the torque sensing means; and feedback means embodying RC time constant means (941-946) connected between the motor and the pulse width modulation circuit for preventing variations in the net energy applied to the motor due to variations in the supply voltage.
Claim 3
Dependent Claim
105 words
A power steering apparatus as claimed in claim 1, wherein the pulse width modulation circuit comprises: a bridge circuit including a plurality of switching elements, the motor being connected across the bridge circuit; a capacitor and a resistor connected in parallel between the motor and ground, and defining said feedback means; and a comparator having a first input terminal to which the output voltage of the torque sensing means is applied and a second input terminal connected to the junction of the capacitor and the resistor, the output voltage of the comparator being supplied to a gate of the switching element of the bridge circuit.
Claim 4
Dependent Claim
87 words
A power steering apparatus as claimed in claim 1, wherein the torque sensing means comprises a right turn potentiometer for generating an output voltage corresponding to a steering torque exerted by a driver of the vehicle only when the steering torque is in a direction to turn the vehicle to the right and a left turn potentiometer for generating an output voltage corresponding to a steering torque exerted by the driver only when the steering torque is in a direction to turn the vehicle to the left.
Claim 5
Dependent Claim
78 words
A power steering apparatus as claimed in claim 3, wherein: the torque sensing means includes a torque-displacement converter for generating a displacement proportional to a steering torque exerted thereon; and each of the potentiometers has a resistive element and a wiper arm which is linked to the torque-displacement converter so as to be moved along the resistive element by the displacement of the torque-displacement converter, the output voltage of each potentiometer being the voltage at its wiper arm.
Claim 6
Dependent Claim
37 words
A power steering apparatus as claimed in claim 3, further comprising mean (916,917) for preventing the motor from operating when both of the potentiometers generate an output voltage of above a prescribed level at the same time.
References Cited (Backward Citations)
EP0081398A1
Cited
US4661750A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-02-11 | 1994-08-13 | 1995-02-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-02-11 | 1998-08-13 | 1999-02-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-02-11 | 2002-08-13 | 2003-02-12 | $7700.00 | Window Closed / Lapsed |