Hybrid Engine Torque Correction via Lookup Table Updates
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Solution Overview
Problem
Hybrid electric vehicles face challenges in maintaining consistent engine torque delivery due to noise factors such as part-to-part variation and degradation over time, leading to inaccuracies in total transmission input torque, which can affect vehicle performance and fuel efficiency.
Innovation Solution
A controller in the vehicle is programmed to use a table of torque correction factors based on engine speed and torque, updating these factors during steady-state conditions and periodically through a systematic procedure to ensure accurate torque delivery, adjusting both engine and motor torque to maintain constant transmission input torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the engine operates over a wide range of speeds and torque levels, then the vehicle can operate efficiently under various driving conditions, but the engine torque delivery becomes inconsistent due to noise factors such as part-to-part variation and degradation over time
Solution Approach 1:
The system pre-calculates and stores torque correction factors in a lookup table for various engine speeds and torque levels before actual operation. During runtime, the controller simply retrieves the appropriate correction factor from the table based on current operating conditions, avoiding complex real-time calculations and ensuring consistent torque delivery across the entire operating range.
Solution Approach 2:
The system implements a feedback mechanism where the controller continuously monitors actual engine torque delivery and compares it with commanded torque. Based on this feedback, the controller updates the torque correction factors in the lookup table to compensate for degradation and variation over time, maintaining reliable torque delivery across different operating conditions.
2Device complexity
If the controller uses a fixed torque correction factor, then the system complexity is reduced, but the torque delivery accuracy deteriorates over time due to engine degradation and wear
Solution Approach 1:
The system pre-calculates and stores torque correction factors in a lookup table for various engine speeds and torque levels before actual operation. During runtime, the controller simply retrieves the appropriate correction factor from the table based on current operating conditions, avoiding complex real-time calculations and ensuring consistent torque delivery across the entire operating range.
Solution Approach 2:
The torque correction factor is not fixed but dynamically updated based on engine operating conditions. The system adapts the correction factors over time to account for engine degradation and wear, maintaining accurate torque delivery without requiring increased system complexity.
3Measurement precision
If the system updates torque correction factors continuously during operation, then the torque delivery accuracy is maintained, but the processing time and computational load increase
Solution Approach 1:
The system pre-calculates and stores torque correction factors in a lookup table for various engine speeds and torque levels before actual operation. During runtime, the controller simply retrieves the appropriate correction factor from the table based on current operating conditions, avoiding complex real-time calculations and ensuring consistent torque delivery across the entire operating range.
Solution Approach 2:
The correction factor update process is segmented into discrete operating conditions represented as discrete points in the lookup table. Rather than continuously updating for every possible operating condition, the system updates factors at specific speed and torque levels, reducing computational load while maintaining accuracy across the full operating range.
Data Source
AI summary
A table of engine torque correction factors is used to compensate for noise factors. In a hybrid vehicle, the motor is used to measure engine torque during periods of constant transmission input shaft torque. By comparing the measured input torque to the requested engine torque, a controller can update the table of correction factors to compensate for changes in the noise factors. A service procedure may be implemented that systematically provides the controller an opportunity to update many values in the table.