Abstract
A revolutionary steering system for electrical and hybrid power trains is presented. This steering system was developed and patented primarily for un-manned vehicles in service and logistics applications, but can also be used in cars which have individual electrical motors for the wheels of one or two axles (Stania et al. 2008). These electrical motors could primarily be wheel hub motors but also other electrical motors in the vicinity of the wheels, e. g. connected with the wheels by means of a drive shaft to reduce the unsprung masses. Such motor arrangements may occur in pure electrical cars as well as in serial hybrid vehicles.
The revolutionary steering system disposes of the potential to improve manoeuvrability, efficiency and dynamic behaviour of vehicles of all kinds. The patented steering principle is based on the concept to use the torque of the drive motors additionally to the propulsion purposes for steering independent or coupled wheels (torque steering). In the case of manned vehicles the usage of at least two coupled wheels is proposed. The wheels can be coupled by a simplified, light-weight tie rod. Especially for small urban vehicles a much smaller turning circle can be achieved if the innovative steering principle is applied. By means of an appropriate control system the two wheels of an axle or all wheels of a car can be steered sequentially or simultaneously. However, the challenges concerning this control system in terms of velocity and processing capacity are high. At the Hochschule Ravensburg- Weingarten a first prototype was successfully realised proving the general feasibility of the concept and underlining the prominent advantages. Elaborate tests with this vehicle have shown unlimited manoeuvrability combined with promising controllability.
Keywords: steering systems, torque steering, electrical drive train, hybrid drive train