Electric Multi-Mode Steer-by-Wire with Electromagnetic Clutch Backup
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Solution Overview
Problem
Existing steer-by-wire systems lack mechanical redundancy backup and fail to achieve steering angle decoupling of left and right wheels, leading to safety issues when electrical components fail.
Innovation Solution
An electric multi-mode steer-by-wire system with a distributed structure that includes a steering hand wheel unit, steering execution unit, mode selection and display unit, and electronic control unit, enabling switching among three modes (two-side steering-road-wheel independent, steering-trapezoidal, and electric power steering) for redundancy and safety, with mechanical decoupling of steering angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electronic redundancy backup is used to improve functional safety, then safety is improved, but the system lacks mechanical redundancy backup structure and fails when electrical components fail
Solution Approach 1:
The steering system is segmented into multiple independent working modes (steer-by-wire mode, EPS mode, and manual mode), allowing the system to function through different pathways. The electromagnetic clutch segments the mechanical connection, enabling selective engagement/disengagement of mechanical vs. electronic steering paths, thus providing both electronic and mechanical redundancy.
Solution Approach 2:
The system dynamically switches between different working modes based on operational conditions and fault states. The electromagnetic clutch dynamically engages or disengages to transition between steer-by-wire mode (electronic control only) and EPS mode (mechanical connection engaged), providing adaptability and mechanical redundancy when electrical systems fail.
2Stability of the object's composition
If traditional steering-trapezoidal structure is used, then mechanical connection is maintained, but steering angle decoupling of left and right wheels is not achieved
Solution Approach 1:
The steering execution unit is segmented into independent left and right wheel steering mechanisms, each capable of independent angle control. The electromagnetic clutch segments the mechanical connection path, allowing selective engagement of mechanical steering assistance while maintaining the ability to decouple left and right wheel steering angles through electronic control in steer-by-wire mode.
Solution Approach 2:
The steering system achieves multi-functionality by combining steer-by-wire capability with traditional EPS functionality. The same mechanical components serve dual purposes: providing mechanical connection for stability when engaged, and allowing independent wheel control when the electromagnetic clutch is disengaged, thus achieving both mechanical stability and steering angle decoupling.
3Object-affected harmful factors
If mechanical connection is eliminated for steer-by-wire operation, then driver protection in crash is improved, but mechanical redundancy backup is lost
Solution Approach 1:
The electromagnetic clutch acts as an intermediary device that can engage or disengage the mechanical connection between the steering wheel and steering execution unit. In normal steer-by-wire operation, it disengages to eliminate mechanical connection for driver protection. In failure scenarios, it engages to restore mechanical redundancy and provide backup steering capability through EPS mode.
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
Ensures reliable steering even in component failures, enhances safety, and provides flexible steering options, enriching driving experience with manual mode switching and reducing system space requirements.
Implementation Method 1
an electromagnetic clutch, configured to transmit or disconnect torque between the steering wheel and the steering execution unit
Implementation Method 2
a lead screw-nut motion conversion mechanism
Implementation Method 3
the reducer is a worm gear-worm reducer
Data Source
AI summary
An electric multi-mode steer-by-wire system and a mode switching method thereof. The electric multi-mode steer-by-wire system includes a steering hand wheel unit including a steering hand wheel, a road-feeling motor, a reducer and an electromagnetic clutch, a steering execution unit including two steering electric motor mechanisms, a steering gear and two steering road wheels, an electronic control unit configured to control the steering hand wheel unit and the steering execution unit to achieve switching among two-side steering-road-wheel independent steer-by-wire mode, steering-trapezoidal steer-by-wire mode and electric power steering mode, and a mode selection and display unit. The electromagnetic clutch connected to the steering execution unit. The steering electric motor mechanisms drive the steering road wheels to steer independently through lead screw-nut pairs; or respectively form a hydraulic cylinder with the steering gear to jointly or independently drive the steering road wheels to steer with steering-trapezoidal manner.