Axle Torque Limit Control for Vehicle Grade Assist
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Solution Overview
Problem
Existing vehicle systems apply a static torque limit to axles, which impedes performance on hills or road grades, particularly in vehicles with frequent start-and-stop scenarios like delivery vans or taxis.
Innovation Solution
A system that adjusts the axle torque upper limit based on road grade, vehicle speed, and power flow direction using sensors and a processor to determine a clipped axle torque request, ensuring the torque does not exceed the limit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a static torque limit is applied to the vehicle, then wear on the vehicle components is reduced, but performance on hills or road grades is impeded
Solution Approach 1:
The patent applies dynamics by transitioning from a static torque limit to a dynamic torque limit that adjusts in real-time based on road grade conditions. The system continuously monitors road grade via sensors and modifies the torque upper limit accordingly, allowing the torque limit to be movable and adaptive rather than fixed, thereby resolving the contradiction between wear protection and performance.
Solution Approach 2:
The patent implements parameter changes by modifying the torque limit parameter based on road grade measurements. The system changes the torque upper limit value dynamically according to the detected road grade, vehicle speed, and power flow direction, enabling the torque parameter to adapt to varying operating conditions and thus maintain both component protection and performance.
2Reliability
If a static torque limit is applied to the vehicle, then component wear is prevented, but torque application on grades is restricted
Solution Approach 1:
The system makes the torque limit dynamic by continuously adjusting it based on real-time road grade data. When the vehicle is on a grade, the torque upper limit increases accordingly, allowing sufficient axle torque for performance while still protecting components during level operation. This dynamic adjustment resolves the contradiction between torque availability and component protection.
Solution Approach 2:
The patent implements feedback by using road grade sensors to continuously monitor conditions and feed this information back to the torque limit determination logic. The system adjusts the torque upper limit based on this feedback loop, ensuring that torque application is optimized for current road conditions while maintaining component protection, thus resolving the contradiction between force availability and reliability.
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 vehicle performance on varying road grades by dynamically adjusting torque limits, reducing wear and improving operational efficiency.
Implementation Method 1
A road grade of a road section being traversed by the vehicle is measured using a road grade sensor located on the vehicle. The road grade sensor is an accelerometer.
Data Source
AI summary
A vehicle includes a system that performs a method of operating the vehicle. The system includes a road grade sensor for measuring a road grade of a road section being traversed by the vehicle, a speedometer for measuring a vehicle speed, a power flow direction sensor for obtaining a power flow direction of the vehicle, a pedal position sensor for measuring a pedal position, and a processor. The processor is configured to determine an axle torque upper limit for a motor of the vehicle based on the road grade, the vehicle speed and the power flow direction, determine an axle torque request based on the vehicle speed and the pedal position, determine a clipped axle torque request from the axle torque request and the axle torque upper limit, and control the vehicle by implementing the clipped axle torque request at the vehicle.