Superimposition Steering Gearing for Direct Response Control
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Solution Overview
Problem
Existing superimposition steering systems in motor vehicles experience a deteriorating steering response at increasing speeds, leading to an indirect and 'fuzzy' steering experience, particularly in the mid to upper speed range, where turning the steering wheel results in a small reaction at the steered wheels.
Innovation Solution
A method that controls the superimposition gearing to impose a positive superimposition angle within a predetermined angular range for a direct steering response at neutral straight ahead drive, transitioning to a negative superimposition angle outside this range, with speed-dependent and steering-wheel-angle-dependent adjustments to prevent oversteering and maintain a comfortable steering feel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If superimposition steering systems use indirect steering transmission to improve stability at higher speeds, then vehicle stability is improved, but steering response deteriorates causing a fuzzy steering experience
Solution Approach 1:
The patent applies dynamics by making the steering transmission ratio variable rather than fixed. The superimposition steering system dynamically adjusts the steering angle at the steered wheels independently of the steering wheel angle, allowing the system to optimize between direct steering response and indirect steering stability based on driving conditions. This dynamic adjustment resolves the contradiction by enabling both direct feeling when needed and indirect stability when appropriate.
Solution Approach 2:
The patent changes the parameter of steering transmission ratio from a fixed value to a variable parameter. By using a superimposition steering mechanism that adds or subtracts angles from the basic steering transmission, the system can modify the effective steering ratio in real-time. This parameter change allows the vehicle to switch between direct and indirect steering characteristics, resolving the contradiction between response and stability.
2Ease of operation
If superimposition steering systems impose a positive superimposition angle within a predetermined angular range, then direct steering response is achieved, but excessive steering may occur outside this range
Solution Approach 1:
The patent applies local quality by implementing different steering characteristics for different steering wheel angle ranges. Within the predetermined angular range (typically smaller angles), the system imposes a positive superimposition angle to provide direct steering response. Outside this range (larger angles), the system transitions to a negative superimposition angle to prevent excessive steering. This localized differentiation resolves the contradiction by providing appropriate steering behavior for each operating condition.
Solution Approach 2:
The patent segments the steering operation into distinct angular ranges with different superimposition angle characteristics. The steering control is divided into at least two regions: a first region with positive superimposition angle for direct response, and a second region with negative superimposition angle to limit excessive steering. This segmentation allows the system to optimize performance in each region without compromising the other.
Data Source
AI summary
A method for operating a steering system of a motor vehicle includes controlling with a control device a superimposition gearing of a superimposition steering of a front axle of the motor vehicle via an actuator so as to impose via the superimposition gearing a superimposition angle on a steering angle of a steering wheel of the motor vehicle as a function of a speed of the motor vehicle and of the steering angle of the steering wheel, wherein within a predetermined angular range of the steering wheel measured from a position of the steering wheel during a neutral straight ahead drive with neutral superimposition angle, the superimposition angle is positive resulting in a direct steering response; and wherein outside the predetermined angular range the superimposition angle is negative resulting in an indirect steering response.