Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
2001-05-15
2004-07-06
Chin, Gary (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
C701S041000, C180S443000
Reexamination Certificate
active
06760653
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an electric power assisted steering system.
BACKGROUND OF THE INVENTION
Known electric power assisted steering systems include two controllers. A main controller receives signals from a vehicle speed sensor and a torsion sensor. In response to the received signals, the main controller generates an output signal to control an electric motor that provides steering assistance for turning steerable wheels of a vehicle. A secondary controller also receives signals from the vehicle speed sensor and the torsion sensor. In response to the received signals, the secondary controller determines a desired motor torque for the electric motor. The secondary controller also receives a signal from a motor current sensor that senses the actual current of the electric motor. The secondary controller compares the desired motor torque to the actual motor current and, if the difference between the desired motor torque and the actual motor current exceeds a predetermined value, the secondary controller disables the electric motor. Such a system is described in U.S. Pat. Nos. 5,259,473 and 5,271,474.
Two controllers increase both the size and the cost of the electric power assisted steering system. Additionally, since signals from the vehicle speed and the torsion sensors are input into each controller, the installation requires a separate electrical connection to each controller.
SUMMARY OF THE INVENTION
The present invention is an electric power assisted steering system for a vehicle. The electric power assisted steering system comprises a steering gear having a rack bar and a housing. The rack bar is movable linearly relative to the housing for turning steerable wheels of the vehicle. An electric motor is coupled with the rack bar of the steering gear. Energization of the electric motor causes linear movement of the rack bar relative to the housing. At least one vehicle condition sensor senses a vehicle condition and generates a signal indicative of the vehicle condition. A motor current sensor senses an actual current of the electric motor and generates a signal indicative of the actual motor current. A single integrated circuit includes a main processor and a monitoring processor. The main processor receives the at least one vehicle condition signal and, in response, controls the electric motor by controlling the actual motor current delivered to the electric motor. The monitoring processor receives the at least one vehicle condition signal and, in response, determines a desired motor torque. The monitoring processor also receives the actual motor current signal and compares the actual motor current to the desired motor torque to determine if the actual motor current is in an acceptable range and thus, determine if the main processor is properly functioning.
REFERENCES:
patent: 4621327 (1986-11-01), Dolph et al.
patent: 4869334 (1989-09-01), Marumoto et al.
patent: 5001641 (1991-03-01), Makino
patent: 5016249 (1991-05-01), Hurst et al.
patent: 5074626 (1991-12-01), Kramer et al.
patent: 5259473 (1993-11-01), Nishimoto et al.
patent: 5271474 (1993-12-01), Nishimoto et al.
patent: 5360077 (1994-11-01), Nishimoto et al.
patent: 5440487 (1995-08-01), Althoff et al.
patent: 5448480 (1995-09-01), Rauner et al.
patent: 5479081 (1995-12-01), Seibel et al.
patent: 5504679 (1996-04-01), Wada et al.
patent: 5526264 (1996-06-01), Niggemann et al.
patent: 5588118 (1996-12-01), Mandava et al.
patent: 5656897 (1997-08-01), Carobolante et al.
patent: 5832395 (1998-11-01), Takeda et al.
patent: 5912539 (1999-06-01), Sugitani et al.
patent: 5980081 (1999-11-01), Watari et al.
patent: 6422335 (2002-07-01), Miller
patent: 2001/0051845 (2001-12-01), Itoh
patent: 4122016 (1993-01-01), None
patent: WO0146806 (2001-06-01), None
Fruehling, Terry L., “Delphi Secured Microcontroller Architecture”, Delphi Delco Electronics Systems, pp. 33-42, Copyright © 2000 Society of Automotive Engineers, Inc.
Chin Gary
Tarolli, Sundheim Covell & Tummino L.L.P.
TRW Inc.
LandOfFree
Electric power assisted steering system having a single... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electric power assisted steering system having a single..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electric power assisted steering system having a single... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3247952