Cantilevered Worm Gear Brake Bushing for Steer-by-Wire
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Solution Overview
Problem
Steer-by-wire (SbW) systems require increased power and packaging space due to the use of low friction bushings or bearings, which are inefficient in applying resistive torque, leading to larger motor requirements.
Innovation Solution
A SbW system employing a bushing or bearing with a high coefficient of friction to resist rotation, reducing motor output and power consumption, and allowing for smaller motor sizes and reduced packaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If low friction bushings or bearings are used in SbW systems, then efficiency in EPS systems is improved, but motor size and power consumption increase
Solution Approach 1:
The patent changes the coefficient of friction parameter from low (in prior art) to high (in this invention). By selecting bushing materials with a coefficient of friction between 0.15 and 0.35, the system achieves optimal balance between energy efficiency and motor size reduction. This parameter change allows the motor to generate sufficient resistive torque without requiring excessive power, thereby reducing overall motor size and power consumption in SbW systems.
2Ease of operation
If low friction bushings or bearings are used in SbW systems, then rotation resistance is reduced, but motor size increases
Solution Approach 1:
The patent optimizes the coefficient of friction parameter to a specific range (0.15-0.35) that provides adequate rotation resistance while minimizing motor size. This is achieved by selecting appropriate bushing materials and surface treatments that deliver the right amount of friction - not too low to require large motors, not too high to cause excessive wear or energy loss.
3Power
If high power motors are used in SbW systems, then resistive torque is sufficient, but packaging space increases
Solution Approach 1:
By changing the friction parameter in the bushing to an optimal range, the patent enables the use of smaller motors that still generate sufficient resistive torque. This directly reduces the packaging space required for the motor assembly in the vehicle, addressing the space constraints associated with high-power motor designs.
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 high friction bushing or bearing reduces motor torque and power consumption, lowering stress on components and reducing system costs and packaging space, while maintaining effective resistance to rotation.
Implementation Method 1
A friction pad is positioned at the end of the motor shaft, and the friction pad has a coefficient of friction configured to resist rotation of the motor shaft
Data Source
AI summary
A steering assembly including an electric motor, and a motor shaft coupled to and extending from the electric motor to an end. The motor shaft is rotatable about a motor shaft axis by the motor. The steering assembly further includes a friction pad at the end of the motor shaft, where the friction pad has a coefficient of friction configured to resist rotation of the motor shaft.