Steering Column Dual-Motor Feedback for Fast, Compact Steer-By-Wire
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Solution Overview
Problem
In steer-by-wire steering systems, providing driver feedback without using a large motor while maintaining a good response is challenging, as direct acting motors require larger dimensions and additional transmissions can introduce noise.
Innovation Solution
A dual-motor feedback actuator system is employed, comprising a primary motor acting directly on the steering wheel and a secondary motor acting via a transmission, allowing for variable torque production and compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a direct acting motor is used for the feedback actuator, then the response is very good, but the motor must be dimensioned larger to produce the required torque
Solution Approach 1:
The feedback actuator is divided into two separate motors: a first motor for providing feedback torque and a second motor for providing assist torque. This segmentation allows each motor to be optimized for its specific function, with the first motor being smaller and faster-responding since it only needs to provide feedback torque rather than total torque.
2Force
If the torque of a smaller motor is increased via an additional transmission, then the torque is sufficient, but more noise may be produced
Solution Approach 1:
The system segments the torque requirement into two parts: feedback torque handled by the first motor directly on the steering wheel, and assist torque handled by the second motor through the transmission. This reduces the noise burden on the transmission since the first motor's torque needs are met without transmission intervention.
Solution Approach 2:
The control unit acts as an intermediary that determines when and how much assist torque is needed from the second motor, allowing the system to minimize transmission usage and thus minimize noise while still providing sufficient total torque when necessary.
3Force
If a single large motor is used for the feedback actuator, then sufficient torque is provided, but the actuator is not compact and response is slower
Solution Approach 1:
The feedback actuator is segmented into two motors with different characteristics: a smaller first motor optimized for fast response and feedback torque, and a second motor optimized for providing additional assist torque through transmission. This segmentation enables both compact size and fast response while maintaining sufficient torque capability.
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 dual-motor system provides a compact and responsive feedback actuator that simulates steering feel effectively, adapting to driving conditions without the need for large motors or noisy transmissions.
Implementation Method 1
A first electric motor (3) is arranged in the steering wheel (1) and acts directly there. With this motor, lower torques may be produced.
Implementation Method 2
A second electric motor (12) is arranged behind the first motor (3) and acts on the steering wheel (1) via a transmission (13). With this motor, larger torques may be produced as needed.
Implementation Method 3
A second electric motor (12) is arranged behind the first motor (3) and acts on the steering wheel (1) via a transmission (13). With this motor, larger torques may be produced as needed.
Data Source
AI summary
A steering column for a steer-by-wire steering system for a motor vehicle having a steering wheel is disclosed. The steering column includes (i) a fixed steering wheel hub, and (ii) a force-feedback unit which can transmit torque to the steering wheel. The force-feedback unit includes a first electrical motor and a second electrical motor. The first electric motor acts directly on the steering wheel. The second electric motor acts on the steering wheel via a transmission.