Motor vehicles – Steering gear – No mechanical connection between steering shaft and steering...
Reexamination Certificate
2002-03-18
2003-12-09
Morris, Lesley D. (Department: 3611)
Motor vehicles
Steering gear
No mechanical connection between steering shaft and steering...
C180S419000, C180S421000
Reexamination Certificate
active
06659218
ABSTRACT:
TECHNICAL FIELD
This invention relates to steering systems for vehicles. More particularly, this invention relates to a mechanical back-up system for a steer-by-wire system for vehicles and a security system therefor.
BACKGROUND
Automobiles are conventionally equipped with a pair of front road wheels that are steered to enable the vehicle to turn left and right as it maneuvers on land. It is also known to provide actuators for steering rear wheels in automobiles. In the past, vehicle steering systems commonly employed a mechanical connection between the driver-operated hand wheel and the front road wheels of an automotive vehicle. As the driver rotated the hand wheel, a mechanical linkage through the vehicle's tie-rods actuated the road wheels sometimes with the assistance of a power assist steering motor or hydraulic piston.
Recently, steer-by-wire steering systems have been introduced into automotive vehicles to provide road wheel steering function. Included in a typical steer-by-wire steering system is a hand wheel actuator for monitoring the angular position of the steering wheel, and road wheel motor actuators which are controlled by controllers in response to tracking the sensed angular displacement of the hand wheel from a central position. In contrast to prior steering systems, the steer-by-wire steering system does not employ a mechanical linkage between the steering wheel and the individual road wheels. Exemplary of such known steer-by-wire systems is commonly-assigned U.S. Pat. No. 6,176,341, issued Jan. 23, 20001 to Ansari. Other proposed systems are described in “Future Electrical Steering Systems: Realizations with Safety Requirements” by Harter, et al. and “Steer-by-Wire” by Ebner.
Because there is no mechanical linkage between the hand wheel and road wheels in a steer-by-wire system, steering enhancements such as variable-ratio steering and oversteer/understeer correction are easily implemented to improve the drivability and safety of the vehicle. At the same time, mechanical back-up systems are known to engage a traditional mechanical steering linkage in the event of a failure of the electronic steer-by-wire system. See, for example, “Steer-by-Wire” by Dr. Christian Ebner, for a typical example of such a system, which includes a hand wheel actuator having a steering shaft, and a steering column selectively engaging the shaft via a clutch, which is electrically actuated. It would be desirable to provide a steer-by-wire system with a mechanical back-up device that does not require moving parts to engage, thereby improving overall reliability.
At the same time, mechanical column locks, used as a theft deterrent and to prevent the steering wheel from turning as an aid when exiting and entering the vehicle (thereby providing a grab-handle) presents the problem in that its convenient location presents thieves with the opportunity to disable it, and adds undesirable weight at the top of the steering column. Extra weight near the top of the steering column requires a strong support and presents safety issues during a frontal collision.
SUMMARY
The above-discussed and other drawbacks and deficiencies of the prior art are overcome or alleviated by a steering system comprising a hand wheel positioned for manipulation by a driver and a steering shaft, extending from the hand wheel and a magnetic column lock. The steering shaft is supported by a steering column housing so that it can rotate on its own axis. The magnetic column lock includes a rotor attached to steering shaft, a stator attached to column housing, and magnetorheological fluid filling a space between the rotor and stator.
In another aspect of the steering system, the steering shaft extends from the hand wheel through a hand wheel actuator having a position sensor and a motor for providing driver feedback. A steering column extends from a lower portion of said steering shaft to a rack, and includes a pinion at its lower end for engagement with the rack, so that the rack translates left and right when the pinion is rotated in corresponding directions. The rack is connected to the front road wheels and causes the front road wheels to steer when it is translated. An electronic controller receives signals indicative of an angular position of the hand wheel from the position sensor, and a road wheel actuator connected to the steering rack receives signals from the electronic controller and repositions the steering rack in response to the signals from said electronic controller. A magnetic clutch having MR fluid is provided for selectively engaging said steering shaft to said steering column.
REFERENCES:
patent: 5137128 (1992-08-01), Takei et al.
patent: 5598908 (1997-02-01), York et al.
patent: 5602735 (1997-02-01), Wada
patent: 5718131 (1998-02-01), Bobbitt, III
patent: 5732791 (1998-03-01), Pinkos et al.
patent: 5787759 (1998-08-01), Olgren
patent: 5823309 (1998-10-01), Gopalswamy et al.
patent: 5848753 (1998-12-01), Bansbach
patent: 5906120 (1999-05-01), Thacker et al.
patent: 6035739 (2000-03-01), Milton
patent: 6053067 (2000-04-01), Garnault et al.
patent: 6138788 (2000-10-01), Bohner et al.
patent: 6318531 (2001-11-01), Usoro et al.
patent: 6354626 (2002-03-01), Cartwright
patent: 6389343 (2002-05-01), Hefner et al.
patent: 6442462 (2002-08-01), Nishizaki et al.
Park et al., Steer-by-wire using semi-active actuator, Jan. 22, 2002, Pub. No. US 2002/0108804 A1.*
Werner Harter et al, Future Electrical Steering Systems: Realizations with Safety Requirements, SAE Technical Papers Series, Mar. 6-9, 2000, pp 1-9.
Dr. Christian Ebner, Steer-by-Wire, A rough outline of ongoing thoughts, BMW Technik, May 2000, pp1-13.
Card James Myrl
Thomas Steven M
Delphi Technologies Inc.
Morris Lesley D.
Smith Michael D.
Winner Tony
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