Steer-by-Wire Rotation Stop With Fail-Safe Steering Reaction Force
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Solution Overview
Problem
Steer by wire type steering systems lack mechanical connection between the steering wheel and vehicle wheels, leading to indefinite rotation of the steering wheel, reduced driver's steering feeling, and instability, and fail to generate steering reaction force during motor or electronic control device malfunctions.
Innovation Solution
A steer by wire type steering apparatus with a rotating shaft, housing, ball seating portion, support member, ball support elastic member, and actuator that mechanically limits steering wheel rotation at maximum point and generates physical steering reaction force even in the event of motor or electronic control device failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a steer by wire type steering system is used to eliminate mechanical connection components, then the vehicle can achieve more precise electronic control and reduced mechanical complexity, but the driver's steering feeling and steering stability are reduced due to the lack of mechanical connection between the steering wheel and vehicle wheels
Solution Approach 1:
The patent introduces a reaction force generation mechanism as an intermediary between the steering wheel and the driver. This mechanism includes a reaction force motor that generates artificial reaction force based on steering input signals, compensating for the loss of natural mechanical feedback. The reaction force motor acts as a mediator that simulates the mechanical connection's feedback function through electronic control.
Solution Approach 2:
The patent replaces the mechanical connection system with an electronic control system. Instead of relying on physical mechanical links between the steering wheel and wheels, the system uses sensors, controllers, and motors to detect steering input and generate corresponding wheel movement and reaction force. This substitution maintains steering stability through electronic feedback loops while eliminating complex mechanical components.
2Ease of operation
If the steering wheel is allowed to rotate indefinitely without mechanical connection, then the steering system can operate with greater freedom of movement, but the driver's steering feeling deteriorates and the steering wheel may rotate beyond the maximum rotation point of the vehicle wheel
Solution Approach 1:
The patent implements a feedback mechanism where sensors detect the steering wheel's rotation angle and position, and this information is fed back to the control system. The controller uses this feedback to determine when the maximum rotation point is reached and to generate appropriate reaction forces to prevent further rotation. This closed-loop feedback ensures the steering wheel operates within safe limits while maintaining natural steering feel.
Solution Approach 2:
The patent applies preliminary anti-action by generating reaction force before the steering wheel can rotate beyond its maximum point. The system monitors steering input and preemptively generates counteracting reaction force when approaching the rotation limit, preventing the steering wheel from rotating indefinitely. This preliminary action maintains steering feeling by providing resistance before excessive rotation occurs.
3Adaptability or versatility
If a motor or electronic control device malfunctions in a steer by wire system, then the system can continue to operate with redundancy, but steering reaction force cannot be generated leading to deteriorated driver steering feel and stability
Solution Approach 1:
The patent implements beforehand cushioning by preparing backup reaction force generation mechanisms that can activate when the primary motor or electronic control device fails. The system includes redundant components and pre-programmed failure modes that ensure reaction force can still be generated even when parts of the system malfunction. This cushioning approach maintains steering stability and driver feel during fault conditions.
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
Enhances driver's steering feel and stability by preventing further rotation of the steering wheel and providing steering reaction force, ensuring safety and stability even in system failures.
Implementation Method 1
a ball support elastic member coupled to the housing and elastically supporting the ball to another side in the circumferential direction
Data Source
AI summary
A steer by wire type steering apparatus according to the present embodiments comprises a rotating shaft that rotates in conjunction with a steering shaft, a housing provided with a ball seating portion at one end and a ball is coupled and supported between the ball seating portion and an inner circumferential surface of the rotating shaft, a support member disposed inside the housing and provided with a protruding support portion for supporting the ball to one side in a circumferential direction while protruding in an axial direction, a ball support elastic member coupled to the housing and elastically supporting the ball to another side in the circumferential direction, and an actuator for moving the support member in the axial direction.