Burn-and-coast control for emission suppression
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Solution Overview
Problem
The existing burn-and-coast control in vehicles with internal combustion engines leads to emission deterioration due to frequent engine stop and restart, causing decreased cooling water and catalyst temperatures, resulting in increased emissions.
Innovation Solution
A travel control apparatus that includes a speed controller and a determination part to execute emission suppression control by adjusting the burn-and-coast control, preventing engine stop during coasting control when emission deterioration is detected, and maintaining engine operation during coasting to prevent temperature drops and emission increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If burn-and-coast control is executed with frequent engine stop and restart, then fuel efficiency is improved, but emission deteriorates due to temperature drops
Solution Approach 1:
The control apparatus changes the operating parameters of the internal combustion engine by adjusting the lower limit value of the engine rotation speed threshold based on engine temperature conditions. When the engine temperature is low, the threshold is raised to prevent coasting control that would cause further temperature drops and increase emissions. When temperature is adequate, normal coasting control is permitted to maintain fuel efficiency.
Solution Approach 2:
The system continuously monitors engine temperature and uses this feedback to dynamically adjust the coasting control decision-making process. The determination of whether to permit coasting control is based on real-time temperature data, creating a closed-loop control system that balances fuel efficiency and emission control based on current engine state.
2Loss of energy
If engine rotation is stopped during coasting control, then fuel consumption is reduced, but cooling water temperature and catalyst temperature decrease
Solution Approach 1:
The system performs preliminary assessment of engine temperature conditions before permitting coasting control. By checking whether the engine rotation speed exceeds the threshold and whether temperature conditions are favorable in advance, the control apparatus prevents coasting control that would lead to harmful temperature drops, while still allowing it when safe to do so for fuel savings.
3Speed
If burn control is repeatedly executed to accelerate vehicle, then driving performance is improved, but emission increases due to frequent engine restart
Solution Approach 1:
The control apparatus dynamically adjusts the engine rotation speed threshold parameter based on temperature conditions. This parameter change prevents frequent engine restarts that would occur with aggressive burn-and-coast control when temperatures are low, thereby reducing emission during restart while still permitting performance-oriented control when temperatures are adequate.
Data Source
AI summary
A travel control apparatus is provided with: a speed controller that controls speed of a vehicle having an internal combustion engine; and a determination part that determines an emission deterioration state of the internal combustion engine. The speed controller is configured to execute burn-and-coast control that repeatedly executes burn control in which the vehicle is accelerated by driving force of the internal combustion engine, and coasting control in which the vehicle is driven by inertia, by stopping the generation of the driving force or rotation of the internal combustion engine. The speed controller is configured to execute emission suppression control that suppresses emissions by adjusting the burn-and-coast control when the emission deterioration state of the internal combustion engine is determined by the determination part.