Electric Power Steering Friction Control for Stability
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Solution Overview
Problem
Existing power steering systems fail to provide sufficient mechanical friction when the steering wheel is held still, leading to reduced steering stability and increased friction loss when the wheel is turned.
Innovation Solution
An electric power steering apparatus that uses a friction controller and motor to generate and apply appropriate mechanical friction to the steering wheel, determined by a steering torque sensor and converted into a current value to enhance stability and reduce friction loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If mechanical friction is increased to improve steering stability when the steering wheel is held still, then steering stability is improved, but friction loss increases when the steering wheel is turned
Solution Approach 1:
The patent applies dynamic control by varying the pressing force of the rack guide on the pinion based on steering conditions. A pressing force adjustment mechanism modifies the friction characteristics in real-time: increasing pressing force (and thus friction) when the steering wheel is held still to improve stability, and reducing pressing force when the steering wheel is turned to minimize friction loss. This dynamic adjustment resolves the contradiction between maintaining steering stability and reducing energy loss.
2Stability of the object's composition
If a rack guide pressing mechanism is added to provide friction for steering stability, then steering stability is improved, but device complexity increases
Solution Approach 1:
The patent merges the rack guide pressing mechanism with the existing power steering components. The rack guide is integrated into the pinion support structure, and the pressing force adjustment is achieved by modifying the existing hydraulic or electric actuator control system. This integration approach provides the necessary friction for steering stability while minimizing additional complexity by utilizing and adapting existing system elements rather than adding completely separate mechanisms.
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 system improves steering stability by electrically generating and applying friction when the steering wheel is held still and reduces friction loss when turned, resulting in a simpler, lighter, and cost-effective steering mechanism.
Implementation Method 1
an electric motor that generates a steering assisting force against a steering shaft in accordance with operation of a steering wheel
Implementation Method 2
a steering torque sensor that detects a steering torque value depending on operation of the steering wheel
Data Source
AI summary
An electric power steering device wherein mechanical friction is electrically provided. A steering torque value is detected by a steering torque sensor according to the operation of a steering wheel. An assist current value is calculated by an assist control section on the basis of the steering torque value. A target current value based on the assist current value is determined. For providing friction to the operation of the steering wheel, a friction control section and a friction torque value/current value conversion section generate a corrected steering torque value. A second corrected target current value is created by correcting a first corrected target current value by a friction current value. The corrected steering torque value is obtained by correcting the steering torque value by a friction torque value. The target current value is generated, resulting in a motor being subjected to driving control.