Combustion Engine Shutdown Control via Speed Profile Simulation
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Solution Overview
Problem
Current methods for reducing fuel consumption in vehicles, such as coasting and reduced engine torque, do not always achieve optimal results due to unnecessary fuel consumption and inefficient engine braking, especially during downhill slopes or speed reductions.
Innovation Solution
A method and system that simulate future speed profiles to determine the applicability of coasting and assess conditions for shutting down the combustion engine, ensuring that system conditions are met to secure vehicle function and prevent excessive speed, thereby optimizing fuel savings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If coasting is applied to reduce fuel consumption, then fuel efficiency is improved, but vehicle speed control becomes difficult and may exceed maximum permitted speed
Solution Approach 1:
The system performs preliminary simulation of future speed profiles before actual coasting execution. By predicting the vehicle speed trajectory in advance and evaluating whether it will exceed maximum permitted speed, the system can proactively adjust coasting duration or initiate braking preparation, thus resolving the contradiction between fuel efficiency and speed control.
2Use of energy by moving object
If combustion engine is shut down during coasting to save fuel, then fuel consumption is reduced, but vehicle functionality and braking capability may be compromised
Solution Approach 1:
The system continuously monitors system conditions (brake temperature, battery charge state, air pressure) during coasting with engine shutdown. Based on real-time feedback, the control unit can dynamically adjust the coasting strategy - either extending engine shutdown for fuel savings or resuming engine operation to maintain vehicle functionality, thus resolving the contradiction between fuel efficiency and reliability.
3Use of energy by moving object
If engine shutdown is implemented without proper evaluation, then fuel savings increase, but inconsistent shutdowns occur affecting driveability
Solution Approach 1:
The system evaluates multiple conditions in advance before implementing engine shutdown - including minimum coasting duration, system state readiness, and road gradient analysis. This preliminary evaluation ensures that engine shutdowns occur only under appropriate conditions, preventing inconsistent shutdowns that would affect driveability while still achieving fuel savings.
4Use of energy by moving object
If coasting is applied on downhill slopes, then fuel consumption is reduced, but brake systems may overheat due to excessive speed reduction requirements
Solution Approach 1:
The system monitors brake temperature and cooling requirements in real-time during coasting operations. When feedback indicates that brakes are approaching overheating thresholds, the control unit adjusts the coasting strategy - either reducing coasting duration, maintaining engine operation for braking capability, or initiating earlier braking interventions, thus resolving the contradiction between fuel efficiency and brake temperature management.
Data Source
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AI summary
The present invention relates to a method and a system arranged for the control of a combustion engine in a vehicle. According to the invention, at least one future speed profile vSim coast for an actual speed vact of the vehicle during a road section is simulated. The simulation is based on information about the road section, and assumes that coasting will at least partly be applied during the road section. Subsequently, an applicability for coasting during the road section is evaluated. Subsequently, it is evaluated whether the combustion engine may be shut down during a coasting for at least a part of the road section that is deemed applicable. The evaluation of the shutdown of the combustion engine is here based at least on whether one or several system conditions for engine shutdown have been met, on one or several properties for one or several brake systems in the vehicle, and on a shutdown period TICE_off, when the combustion engine could be shut down. The combustion engine is then controlled based on this evaluation of turning off the engine.