Electric Power Steering Torque Sensor Failure Recovery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electric power steering systems fail to provide assistive torque when the torque sensor fails, especially in vehicles without a steering angle sensor, rendering the system manually operable.
Innovation Solution
An electric power steering apparatus that includes a torque detector, a motor, a rotor angular displacement detector, and a motor controller, with an abnormality detector to control the motor based on rotor angular displacement, allowing assistive torque generation even if the torque sensor is faulty, using a stored characteristic curve to adjust the electric current based on vehicle speed and angular displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the torque sensor fails and is unable to detect the steering torque, then the electric motor control must rely on steering angular velocity calculation, but on vehicles without a steering angle sensor this results in cancellation of motor assistance and manual operation only
Solution Approach 1:
The patent uses the rotor angular displacement detector as an intermediary component to provide angular displacement information that serves dual purposes: normal motor control and torque estimation during torque sensor failure. This intermediary data source enables the system to maintain steering assistance without requiring a separate steering angle sensor.
Solution Approach 2:
The rotor angular displacement detector performs multiple functions: it provides angular displacement information for normal motor control operation and simultaneously serves as a backup for torque estimation when the torque sensor fails. This multi-functionality eliminates the need for dedicated backup sensors in vehicles without steering angle sensors.
2Adaptability or versatility
If the system uses steering angular velocity calculated from steering angle sensor output to control motor current, then steering assistance can be maintained, but the system becomes inapplicable to vehicles without steering angle sensors
Solution Approach 1:
The rotor angular displacement detector acts as an intermediary that provides angular displacement data which can be processed to estimate torque. This intermediary approach enables the system to function on vehicles without steering angle sensors, as the rotor angular displacement can be measured directly from the motor rotor position.
Solution Approach 2:
The patent replaces the mechanical steering angle sensor system with an electrical measurement approach using the rotor angular displacement detector. By measuring the rotor position electrically and using it to estimate torque through control algorithms, the system eliminates dependence on mechanical steering angle sensors, thereby improving adaptability to different vehicle platforms.
3Reliability
If the torque sensor is made redundant with backup detection methods, then steering assistance reliability improves, but the device complexity and cost increase
Solution Approach 1:
The rotor angular displacement detector is designed to serve dual purposes: primary motor control function and backup torque estimation function. This multi-functionality provides redundancy for steering assistance reliability without adding separate backup detection systems, thereby avoiding increased device complexity and cost.
Solution Approach 2:
The system uses its own existing components (motor rotor and angular displacement detector) to provide backup torque detection capability. Instead of adding external redundant sensors, the system leverages its inherent motor control components to maintain steering assistance during torque sensor failure,实现ing self-service redundancy.
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
Enables continuous application of steering assistive force across the entire vehicle speed range, preventing excessive current supply and ensuring the system remains functional even without a functioning torque sensor.
Implementation Method 1
a torque detector for detecting a torque generated in a steering system
Implementation Method 2
a rotor angular displacement detector for detecting an angular displacement of a rotor of the motor
Implementation Method 3
a motor for applying an assistive torque to a rotational shaft of the steering system
Data Source
AI summary
Disclosed is an electric power steering device capable of applying a prescribed steering assist force to a steering assembly, even when a torque sensor is out of order and the electric power steering device is in a state of being unable to sense steering torque by the torque sensor. Using an angle of rotation of a rotating element, which is detected by a resolver that serves as a rotating element angle of rotation sensing unit of a motor, a steering angle and a steering angular velocity are estimated, and a prescribed steering assist force is applied to a steering assembly by the motor, on the basis of an estimated steering angle and/or an estimated steering angular velocity.