Engine Shutdown Timing With Clutch-Air Flap Synchronization
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Solution Overview
Problem
Existing vehicle powertrain control systems, particularly those with 'stop and start' and 'coasting stop' functions, experience significant engine stop and restart cycles, leading to increased fuel consumption and imperceptible engine shutdowns, which are challenging to manage due to differing actuator dynamics between the engine air shutter and injection systems.
Innovation Solution
The method anticipates engine stopping by synchronizing the opening of the clutch with the closing of the engine air shutter, using advanced communication between the transmission and engine computers to coordinate these events, ensuring simultaneous closure of the air shutter and cut-off of injection, and anticipating clutch opening during 'coasting stop' or 'sailing' to achieve seamless disconnection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the clutch opening and air flap closing are commanded at the same time, then the control sequence is simplified, but the generator continues to produce electrical power causing energy loss and the shutdown is not smooth
Solution Approach 1:
The patent applies preliminary action by commanding the air flap closure before the clutch opening. This sequencing ensures that the generator is disconnected from the electrical system before the clutch opens, preventing the generator from producing electrical power during the shutdown transition. The air flap closing is initiated at a first time, and only after it is confirmed closed does the system command the clutch opening at a second time.
2Productivity
If the air flap closure and fuel injection cut-off are commanded simultaneously, then the shutdown is efficient, but the 300 ms delay in air flap closure causes mismatched actuator dynamics and imperfect shutdown quality
Solution Approach 1:
The patent applies preliminary action by anticipating the air flap closure command relative to the fuel injection cut-off command. Since the air flap has a 300 ms delay between command and actual closure, the system sends the air flap closure command earlier than the fuel injection cut-off command. This timing adjustment ensures that both actuators reach their final states simultaneously, achieving smooth engine shutdown with minimal vibrations and acoustic noise.
3Ease of operation
If the engine shutdown is made imperceptible to users, then user comfort is improved, but the coordination between multiple actuators with different dynamics becomes more complex
Solution Approach 1:
The patent applies preliminary action by anticipating control commands for actuators with known delays. The transmission control unit receives information about imminent clutch opening and sends anticipatory commands to the engine control unit for air flap closure and fuel injection cut-off. This coordinated timing strategy ensures all actuators complete their actions simultaneously, making the shutdown imperceptible to users while managing complexity through pre-planned sequencing.
Solution Approach 2:
The patent applies feedback by having the transmission control unit send information about the imminent opening of the clutch to the engine control unit. This feedback loop allows the engine control unit to adjust its timing of air flap closure and fuel injection cut-off commands based on the actual state and upcoming actions of the clutch, ensuring precise synchronization despite different actuator dynamics.
Data Source
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AI summary
Method for controlling a vehicle power train comprising a heat engine connected to the transmission of the vehicle by a clutch that is controlled between an open position and a closed position of the transmission by a transmission calculator (ATCU) exchanging information with a heat engine calculator (ECU), in such a way as to close the air flap of the engine and to disconnect the engine from the transmission when the vehicle is rolling, characterized in that the shutdown of the heat engine is early in relation to the opening of the clutch (E), in such a way that said opening occurs at the same time that the air flap (V) of the engine closes.