Engine EGR Control During Shifts
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Solution Overview
Problem
Existing control methods for internal combustion engines with manual transmissions fail to efficiently recirculate exhaust gas (EGR) during gear shifts due to the exhaust passage being filled with fresh air during fuel-cut, leading to prolonged periods where EGR cannot be introduced into the intake passage, which hampers fuel efficiency improvements.
Innovation Solution
A control method that determines whether to perform fuel-cut based on vehicle operating conditions during shifts, predicting the fuel efficiency benefits of EGR recirculation post-shift, and adjusting the fuel-cut timing to ensure the exhaust passage is filled with exhaust gas before resuming EGR, thereby optimizing fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If fuel-cut is performed upon shifting during EGR execution, then fuel efficiency during shift is improved, but EGR recirculation cannot be performed immediately after shift causing prolonged period of reduced fuel efficiency
Solution Approach 1:
The control device predicts whether EGR execution is favorable after shift based on vehicle operating conditions before the shift occurs. This preliminary assessment allows the system to prepare the optimal control strategy in advance, determining whether to maintain or cancel fuel-cut to ensure favorable EGR execution conditions are met post-shift.
Solution Approach 2:
The fuel-cut control strategy is made dynamic and adaptive based on predicted EGR favorability. The control device flexibly adjusts the fuel-cut cancellation timing according to real-time vehicle operating conditions and predicted post-shift EGR conditions, transitioning from fixed fuel-cut execution to condition-based dynamic control.
2Loss of time
If fuel-cut is not performed upon shifting, then EGR can be immediately reintroduced post-shift, but fuel efficiency during shift is not optimized
Solution Approach 1:
The control device uses feedback from vehicle operating conditions (accelerator opening degree, engine load, vehicle speed) to predict post-shift EGR favorability. This feedback mechanism allows the system to continuously monitor conditions and adjust fuel-cut control decisions based on the predicted ability to execute EGR favorably after the shift.
Data Source
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AI summary
Upon shifting during execution of EGR, vehicle operating condition after shift is predicted at a timing at which fuel-cut condition is satisfied. When it is predicted that fuel efficiency of a case where fuel-cut is not performed is relatively improved, the fuel-cut is not going to be performed. On the other hand, when it is predicted that fuel efficiency of a case where the fuel-cut is performed is relatively improved, the fuel-cut is going to be performed. That is, upon shifting during execution of EGR, when it is predicted that fuel efficiency improving effect by EGR after shift is relatively large, the fuel-cut is not going to be performed, whereas when it is predicted that fuel efficiency improving effect by EGR after shift is relatively small, the fuel-cut is going to be performed. With this, fuel efficiency of vehicle can be relatively improved upon shifting during execution of EGR.