Engine Cam Phase Control for Stable Combustion During Fuel-Cut Transition
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Solution Overview
Problem
The existing control method for internal combustion engines with both variable intake and exhaust cam phase mechanisms can cause increased valve overlap periods during cleaning operations, leading to degraded combustion and potential engine stall when transitioning from decelerating fuel-cut to normal operation.
Innovation Solution
A control apparatus that selectively performs either intake-side or exhaust-side cleaning control, inhibiting the other, to prevent excessive valve overlap and ensure stable combustion by controlling the cam phases to specific advanced or retarded values, and uses detection mechanisms to confirm completion of cleaning processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If both intake-side and exhaust-side cleaning controls are performed during decelerating fuel-cut operation, then foreign matter removal effectiveness is improved, but valve overlap period becomes excessively long causing degraded combustion and potential engine stall
Solution Approach 1:
The cleaning control is segmented into separate intake-side and exhaust-side operations that are executed alternately rather than simultaneously. The control apparatus determines whether to perform intake-side cleaning control or exhaust-side cleaning control based on intake air amount and engine operating conditions, ensuring that only one cleaning operation is active at any given time. This segmentation prevents the harmful叠加 effect of both cleaning controls running concurrently.
Solution Approach 2:
The control apparatus dynamically adjusts the cleaning control strategy based on real-time engine operating conditions. It monitors intake air amount, engine speed, and other parameters to determine the appropriate cleaning mode. The system can switch between intake-side cleaning, exhaust-side cleaning, or normal operation modes, making the cleaning process adaptive to current engine states rather than fixed.
2Reliability
If intake cam phase is controlled to most advanced value and exhaust cam phase to most retarded value during cleaning control, then cleaning effectiveness is improved, but combustion stability deteriorates when transitioning from fuel-cut to normal operation
Solution Approach 1:
The control apparatus performs preliminary assessment of engine operating conditions before initiating cleaning control. It checks intake air amount, engine speed, and other parameters to ensure the engine is in a suitable state for cleaning operation. This preliminary check prevents cleaning control from being activated during conditions where it would harm combustion stability, such as during transitions from fuel-cut to normal operation.
Solution Approach 2:
The control apparatus continuously monitors engine operating conditions during cleaning control and uses this feedback to adjust or terminate the cleaning operation. It detects changes in intake air amount, engine speed, and combustion characteristics, and responds by modifying the cam phase control strategy or ending the cleaning mode when necessary to maintain combustion stability.
Data Source
AI summary
A control apparatus for an internal combustion engine, which, in the case of intake-side and exhaust-side cleaning controls being performed, is capable of ensuring stable combustion of a mixture when the engine is returned from a decelerating FC operation to a normal operation, thereby making it possible to enhance marketability. The control apparatus for the engine includes an ECU. The ECU performs intake-side cleaning control for controlling an intake cam phase CAIN to a predetermined most advanced value CAIN_ADV so as to increase a valve overlap period of an intake valve and an exhaust valve, and performs exhaust-side cleaning control for controlling an exhaust cam phase CAEX to a predetermined most retarded value CAEX_RET so as to increase the valve overlap period of the intake valve and the exhaust valve. Further, during execution of one of the intake-side and exhaust-side cleaning controls, the ECU inhibits execution of the other.