Engine Torque Control for Reverse Shock Reduction
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Solution Overview
Problem
During coasting mode in vehicles, engine-turbine reverse shock occurs due to rapid engine torque rise after shifting, leading to reduced fuel efficiency and increased NOx emissions when the engine is re-accelerated, as the engine RPM exceeds the turbine RPM.
Innovation Solution
A control system and method that utilize sensors to monitor accelerator pedal, engine RPM, and turbine RPM signals, outputting a D-stage connection signal and engine torque limitation signal during tip-in conditions in coasting mode, and releasing the torque limitation when the engine RPM exceeds the turbine RPM, thereby controlling the engine and transmission to reduce engine-turbine reverse shock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the engine torque limitation signal is released after shift ends, then the vehicle acceleration performance is improved, but engine-turbine reverse shock occurs causing increased NOx emissions
Solution Approach 1:
The control system applies preliminary anti-action by detecting the engine-turbine reverse condition (engine RPM exceeding turbine RPM) and maintaining the engine torque limitation signal to prevent the harmful effect of rapid torque rise that causes NOx emissions. This anticipatory control prevents the reverse shock before it fully occurs.
Solution Approach 2:
The control system uses feedback by continuously monitoring engine RPM and turbine RPM signals to detect when engine RPM exceeds turbine RPM after shift. Based on this feedback, the controller maintains or releases the torque limitation signal to control engine torque rise and prevent excessive NOx emissions while enabling acceleration.
2Power
If the engine torque rises rapidly after shift, then the vehicle acceleration response is improved, but engine-turbine reverse shock occurs reducing fuel efficiency
Solution Approach 1:
The control system prevents energy loss from engine-turbine reverse shock by maintaining the torque limitation signal when detecting reverse conditions, thereby preliminarily counteracting the harmful effect of rapid torque rise that would otherwise cause fuel efficiency degradation.
Solution Approach 2:
Through continuous monitoring of engine and turbine RPM, the system uses feedback to determine when to maintain or release torque limitation, optimizing the balance between power delivery and fuel efficiency by preventing reverse shock conditions.
3Speed
If the D-stage connection signal is entered quickly, then the transmission response is improved, but torque-to-shift connection oil pressure shortage occurs
Solution Approach 1:
The control system applies preliminary action by entering the engine torque limitation signal before the D-stage connection is complete, thereby preemptively controlling engine torque to prevent the harmful effect of oil pressure shortage during the torque-to-shift connection process.
Data Source
AI summary
The present disclosure provides a control method for an engine and a transmission. The control method may include: determining whether a current mode corresponds to a coasting mode; outputting a neutral operation signal to the transmission when the current mode corresponds to the coasting mode; determining whether an operation condition corresponds to a coasting mode release condition based on the signal of each sensor; outputting a D-stage connection signal to the transmission and outputting an engine torque limitation signal to the engine when the operation condition corresponds to the coasting mode release condition; determining whether the operation condition corresponds to a release of the engine torque limitation condition according to an entry of D stage and the signals of the engine RPM and turbine RPM; and outputting a normal operation signal to the engine when the operation condition corresponds to the release of the engine torque limitation condition.