Steering Wheel Magnetorheological Brake for Wide Torque Control
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Solution Overview
Problem
Existing steering devices face challenges in achieving precise and smooth steering behavior while providing a wide range of brake moments, from low to high, with minimal transition and high control quality, all within a limited installation space.
Innovation Solution
A steering device with a magnetorheological brake system featuring two continuously rotatable brake components, one with a disc contour and the other with rolling bodies, allowing for adjustable brake moments with low basic friction and high maximum torque, achieved through separate control of the electrical coils.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If high braking torques are provided using friction clutches, then maximum braking torque is improved, but base friction increases unfavorably
Solution Approach 1:
The braking system is segmented into multiple independent friction surfaces (first friction surface, second friction surface, third friction surface) that can be selectively activated. This allows the system to distribute the braking torque across different surfaces, enabling high maximum braking torque while maintaining low base friction by keeping most surfaces inactive during normal operation.
Solution Approach 2:
The braking system dynamically switches between different friction surfaces based on operating conditions. The control unit selectively activates specific friction surfaces to match the required braking torque, transitioning from using only the first friction surface at low speeds to incorporating second and third friction surfaces at higher speeds, thereby optimizing the balance between maximum braking torque and base friction.
2Force
If friction surfaces are increased to achieve high braking torque, then maximum braking torque is improved, but device size increases
Solution Approach 1:
The braking system uses multiple friction surfaces arranged in a compact configuration around the steering shaft. By segmenting the braking function across different surfaces (axial, radial, and oblique orientations), the system achieves high maximum braking torque without requiring a single large friction surface, thus maintaining a compact device size suitable for dashboard installation.
3Force
If electric motors are used to provide high braking torque, then maximum braking torque is improved, but response time increases and mass moment of inertia increases
Solution Approach 1:
The patent replaces electric motors with a purely mechanical braking system using friction surfaces and a magnetorheological medium. This mechanical system provides instantaneous response to braking commands without the inertia and response delays inherent in electric motors, while still achieving the required maximum braking torque through the coordinated action of multiple friction surfaces.
4Force
If magnetorheological brakes are used, then maximum braking torque is improved, but base torque increases relative to maximum torque
Solution Approach 1:
The braking system segments the torque generation function between passive friction surfaces and active magnetorheological elements. The multiple friction surfaces provide the primary braking torque through mechanical friction, while the magnetorheological medium provides supplemental braking force when activated. This segmentation allows the system to achieve high maximum braking torque while maintaining low base torque, as the magnetorheological component only activates when needed.
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 solution enables a wide range of brake moments with precise control, low basic friction, and high maximum torque, improving steering precision and comfort while reducing the device's size and power consumption.
Implementation Method 1
at least one circumferential gap, at least partially filled with a magnetorheological medium, is formed between the first and second brake components
Implementation Method 2
A first electrical coil generates a (first) controlled magnetic field in a first braking gap section
Data Source
Figure 1~2
Figure 3a~3c
Figure 4a~6
AI summary
Steering device (100) for controlling a vehicle by means of a movable steering unit (301), wherein a movement of the steering unit (301) can be braked by means of a magnetorheological braking device (1). The braking device (1) comprises a stationary holder (4) and two brake components (2, 3). One brake component (2, 3) can be rotated by the steering unit (310). One brake component (2, 3) is connected to the holder (4) for conjoint rotation. The two brake components (2, 3) can be continuously rotated relative to one another about a rotational axis (20). A first brake component (2) extends along the rotational axis (20) and comprises a core (21) made of a magnetically conductive material. The second brake component (3) comprises a hollow casing part (13) extending around the first brake component (2). A peripheral gap (5) which is filled with a magnetorheological medium (6) is provided between the first and the second brake component (2, 3). The gap (5) comprises two different brake gap portions (5a, 5b). In a first brake gap portion (5a), a disc contour (41) is formed between the casing part (13) and the core (21). In a second brake gap portion (5b), a plurality of roller bodies (11) are arranged around the circumference of the core (21).