Motor vehicles – Steering gear – No mechanical connection between steering shaft and steering...
Reexamination Certificate
2000-01-06
2001-07-24
Hurley, Kevin (Department: 3619)
Motor vehicles
Steering gear
No mechanical connection between steering shaft and steering...
C180S315000
Reexamination Certificate
active
06263997
ABSTRACT:
BACKGROUND OF THE INVENTION
This application claims the priority of International Application PCT/EP98/01344, filed Mar. 7, 1998, and German patent 197 13 245.6, filed Mar. 29, 1997, the disclosure of which are expressly incorporated by reference herein.
Modern motor vehicles usually have, as the operating elements, a steering wheel and various pedals, in particular brake pedal and accelerator pedal. By way of their connection to the parts which they activate these operating elements are also suitable for providing feedback on the position set for the particular part or for the driving condition of the vehicle. This particularly applies to the steering wheel because, in the case of steering, there is no inactive condition and there is a direct and noticeable mutual relationship between the steering wheel and the position of the wheels.
In such a the vehicle, but particularly in passenger cars, the steering wheel also frequently represents an annoying element, not only because of its substantial spatial requirement but also because of its position, fixed for handling reasons, in front of the driver as the operating person.
There has, therefore, been no lack of attempts in motor vehicle design to realize a steering system in the form of operating levers as so-called side-sticks, somewhat analogous to aircraft construction. The operating relationships are by no means directly comparable, both with regard to the space available and also because of a much higher degree of orientation based on instruments in the case of aircraft operation.
In addition, the steering wheel in motor vehicles is also used, often enough, as a support for the hands, as an aid in getting out or the like. This, in association with the actuation of parts by operating levers involves particular difficulties at least if there is no positive connection between the operating lever and the part to be controlled resulting in a direct association of the respective positions, such as is provided with mechanical connections between the steering wheel and the wheels and, therefore, permitting conclusions to be drawn with respect to the position of the part to be controlled from the position of the operating lever.
SUMMARY OF THE INVENTION
The present invention relates to operating lever actuation systems for motor vehicles, in particular for the steered wheels of motor vehicles, in which a positive connection of the operating lever to the part to be controlled and therefore an association of the positions with mechanical or hydraulic apparatus is not provided. This is, for example, the case in the so-called “steer-by-wire” steering systems, i.e. steering systems in which the control instructions are transmitted electrically between an operating element, i.e. an operating lever or a steering wheel, and the corresponding wheel to be steered.
With respect to such operating lever actuation systems in which the movement of the operating lever is virtually independent of the respective part to be controlled, an object of the present invention is to ensure a feedback for making the position of the operating lever to correspond to the position of the respective part which can be controlled or has to be adjusted and, in fact, notwithstanding any forces exerted on the operating lever which have nothing to do with the actual operating function.
This object has been achieved in accordance with the present invention by providing that the control instructions are recorded by a sensor system associated with the operating lever. The sensor system is so placed and/or configured with respect to the actuation and/or arrangement that the forces exerted on the sensor system for control purposes have to be specifically applied and cannot, at least in the usual case, be caused by forces which are exerted on the operating lever for other reasons, be it for support or for other purposes.
Consequently, the operating lever can only be displaced from its basic position by way of the feedback and to match the position of the respectively activated part. The servomotor effecting this adjustment is connected to the operating lever via a gearbox, which not only ensures the necessary, small-step and also, in view of the small adjustment path of an operating lever, sensitive adjustment but also ensures a sufficiently large holding torque in order, in association with the holding force of the motor, to exclude movements of the operating lever resulting from forces not caused by the feedback.
As a gearbox suitable for the foregoing purpose and to be employed in accordance with the present invention, a gearbox, particularly a harmonic drive gearbox, is provided to permit correspondingly high transmission ratios and also, in association there with, correspondingly high holding torques in the opposite direction in the case of a drive by a commercial, small-size and high-speed electric motor with a comparatively small drive power.
An operating unit of this configuration is also characterized by a very low space requirement. This feature is of substantial importance given the restricted spatial conditions in motor vehicles. It also expediently forms an assembly unit with which can be coaxially arranged with a control unit activating the servomotor with feedback from a position pick-up associated with the adjustable part and, if appropriate, an additional brake.
Such an operating unit is advantageous in particular in the so-called “steer-by-wire” steering systems in motor vehicles, particularly as commercially available elements can be used for the overall configuration. These commercially available elements ensure a high level of operating reliability and, because of the small installation volume achieved, can also be employed redundantly, if required.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.
REFERENCES:
patent: 4297845 (1981-11-01), Kyster
patent: 5228356 (1993-07-01), Chuang
patent: 6039142 (2000-03-01), Eckstein et al.
patent: 0 493 795 (1992-07-01), None
Bolte, Uwe, “Das Aktive Stellteil—ein ergonomisches Bedienkonzept, In: Fortschritt Berichte BDE, Reihe 17: Biotechnik, Nr. 75”, 1991, VDI-Berlag, Duesseldorf, Germany.
“Une Saab Sans Volant” Ingenieurs de L'Automobile, No. 671, 1992.
Breuning Edwin
Rachel Ruediger
Crowell & Moring , L.L.P.
Hurley Kevin
Mercedes-Benz Lekungen GmbH
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