Steering Column Damper With Variable Shear Torque Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Steer-by-wire vehicle steering systems lack sufficient feedback torque, leading to potential failure in meeting driver steering demands due to high rotational speeds and reduced angular travel, as they do not provide adequate resistance to excessive steering wheel rotation.
Innovation Solution
A damper system with varying total surface area of shear surfaces between a rotor and a stator, which increases drag and feedback torque as the steering wheel rotates beyond a threshold speed, ensuring sufficient resistance and torque feedback to regulate steering wheel speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a steer-by-wire steering system is used to break the mechanical connection between steering wheel and steered wheels, then the steering wheel can be rotated at high speed without perceived torque feedback increase, but the steering actuator does not have sufficient power to meet the driver's steering demand
Solution Approach 1:
A viscous damper is introduced as an intermediary component between the steering wheel and steering actuator. The damper provides passive resistance to steering wheel rotation through viscous coupling, reducing the power demand on the steering actuator while allowing high-speed rotation capability.
Solution Approach 2:
The viscous damper provides self-regulating feedback torque that automatically increases with steering wheel rotational speed. The damper serves itself by using the kinetic energy of rapid rotation to generate opposing torque through viscous fluid coupling, without requiring external control systems.
2Ease of operation
If a constant surface area damper is used to provide feedback torque, then the damper provides passive resistance, but the feedback torque does not increase with rotational speed to limit maximum steering wheel speed
Solution Approach 1:
The damper transitions from a static constant surface area design to a dynamic variable surface area design. The shear surface area between the rotor and stator changes dynamically with steering wheel rotational speed, allowing the feedback torque to automatically increase when rotation speed exceeds a threshold.
Solution Approach 2:
The physical parameter of shear surface area is changed from constant to variable. As rotational speed increases, the relative displacement between rotor and stator changes the effective shear surface area, thereby changing the damping coefficient and increasing feedback torque proportionally with speed.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The damper system effectively limits excessive steering wheel rotation by providing increased feedback torque, preventing actuator failure and enhancing driver control by varying the surface area of shear surfaces in response to rotational speed, thus ensuring the steering actuator can meet driver demands.
Implementation Method 1
a damper comprising: a housing defining a volume for receipt of damping fluid; a rotor within the housing, the rotor being coupled with the steering column and rotatable therewith; a stator mounted within the housing, the stator being moveable within the housing within a defined range of movement; and a biasing arrangement acting on the stator; wherein each of the stator and rotor comprises a shear surface, the shear surfaces of the stator and the rotor being positioned adjacent one another to generate a resistance to rotation of the rotor when the housing contains damping fluid
Data Source
AI summary
A steering assembly for a steer-by-wire vehicle comprises a rotatably mounted steering column configured for attachment of a steering member at one end, the steering column being rotatable about its longitudinal axis. The steering assembly further comprises a damper having a housing defining a volume for receipt of damping fluid; a rotor within the housing, the rotor being coupled with the steering column and rotatable therewith; a stator mounted within the housing, the stator being moveable within the housing within a defined range of movement; and a biasing arrangement acting on the stator. Each of the stator and rotor comprises a shear surface, the shear surfaces of the stator and the rotor being positioned adjacent one another to generate a resistance to rotation of the rotor when the housing contains damping fluid. Furthermore, the total surface area of the shear surfaces of the stator and the rotor positioned adjacent one another which generates the resistance to rotation of the rotor varies as the steering column is rotated from the straight ahead position by virtue of displacement of the stator relative to the rotor.