Turbocharged Engine Torque Calculation via Boost Disparity Correction
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Solution Overview
Problem
Existing methods for calculating engine brake torque in turbocharged engines, especially during transient operations, face inaccuracies due to the dynamic nature of turbochargers and other factors, affecting the timing and quality of automatic transmission shifting.
Innovation Solution
A method that utilizes an intake manifold pressure model and actual engine boost to calculate engine brake torque by processing engine speed and load data, incorporating a boost map and a torque map to account for discrepancies and provide more accurate torque calculations during acceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If steady-state torque calculation algorithms are used during transient engine operation, then computational simplicity is maintained, but torque calculation accuracy deteriorates due to turbocharger dynamics and transient effects
Solution Approach 1:
The patent applies dynamics by transitioning from static steady-state torque maps to a dynamic calculation method that incorporates real-time engine acceleration rate (dNme/dt). The controller continuously updates torque calculations based on current operating conditions and rate of change, allowing the system to adapt to transient operations while maintaining computational efficiency through predefined lookup tables and correction factors.
Solution Approach 2:
The patent implements feedback by using actual measured parameters (engine speed, accelerator pedal position, transmission shift state) to continuously correct and update the calculated torque values. The system compares calculated torque with actual operating conditions and adjusts calculations accordingly, creating a closed-loop system that improves accuracy during transient operations without requiring complex real-time physics-based modeling.
2Speed
If transmission shift control is based on inaccurate brake torque data during transient operation, then control response speed is maintained, but shift quality deteriorates due to improper shift timing
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing torque correction factors and acceleration compensation data in lookup tables during system initialization or calibration. These pre-prepared data structures allow the controller to quickly retrieve and apply appropriate corrections during transient operations without performing complex real-time calculations, thus maintaining fast response while improving accuracy for transmission shift control.
3Productivity
If turbocharger dynamics are not accounted for in torque calculation, then calculation speed is maintained, but torque tracking accuracy deteriorates during engine acceleration
Solution Approach 1:
The patent introduces an intermediary approach by using measured engine parameters (intake manifold pressure, exhaust pressure, engine speed) as intermediate variables to infer turbocharger state and its impact on torque. Instead of directly modeling complex turbocharger dynamics, the system uses these intermediate measurements to calculate correction factors that account for turbo lag and transient effects, maintaining calculation speed while improving torque tracking accuracy.
Data Source
Figure 1~2
AI summary
Torque being produced by a turbocharged internal combustion engine (12) during acceleration under load is calculated by processing (34) a value for actual boost MAP and a value MAP_NOMINAL selected from a map (32) that contains data values for boost that would prevail during steady state engine operation at a respective speed with the engine developing a respective torque. The selection is made using engine speed N and estimated torque TQI_SP that possesses some inaccuracy due to some disparity between the data value for actual boost and the data value selected from the map. The selection yields a boost disparity value that is used along with the estimated torque to select from a torque map (36) a value for calculated torque that provides a better correlation with actual torque than does the estimated torque during acceleration.