Engine Control Stabilizing Compression Ratio During Transients
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Solution Overview
Problem
In internal combustion engines, the ultra high expansion cycle faces challenges in maintaining actual compression ratio stability during transient operation states, leading to potential knocking or misfire issues, which can reduce output torque and deteriorate fuel efficiency when adjustments are made to the intake valve closing timing or mechanical compression ratio.
Innovation Solution
A control apparatus that includes a reference state determining unit and a control unit to adjust the intake valve closing timing and mechanical compression ratio based on the engine's operation state, using feedback controls to maintain the actual compression ratio within a predetermined range, and employs ignition timing corrections to prevent knocking and misfire, while optimizing output torque and fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the intake valve closing timing is adjusted to control the cylinder intake air quantity, then the output torque can be optimized, but the actual compression ratio shifts causing knocking or misfire
Solution Approach 1:
The patent dynamically adjusts the mechanical compression ratio in response to changes in intake valve closing timing. When the intake valve closing timing is retarded to increase output torque, the mechanical compression ratio is increased to compensate and maintain the actual compression ratio within the optimal range, thereby preventing knocking and misfire while preserving the torque enhancement benefit
Solution Approach 2:
The control apparatus implements a feedback mechanism where the actual compression ratio is continuously monitored based on the intake valve closing timing and mechanical compression ratio settings. When deviations from the target compression ratio are detected, the system automatically adjusts the mechanical compression ratio to restore the actual compression ratio to the optimal range, ensuring combustion stability
2Reliability
If the mechanical compression ratio is increased to maintain actual compression ratio, then knocking is prevented, but the expansion ratio increases causing thermal efficiency loss
Solution Approach 1:
The patent employs dynamic adjustment of the mechanical compression ratio based on real-time operating conditions. Rather than maintaining a fixed high compression ratio, the system only increases the mechanical compression ratio when necessary to compensate for retarded intake valve closing timing, and reduces it when the timing is advanced, thereby minimizing energy losses while maintaining knocking prevention
3Reliability
If feedback control is implemented to maintain actual compression ratio, then combustion stability is improved, but the device complexity increases
Solution Approach 1:
The patent replaces complex mechanical compression ratio adjustment mechanisms with a control system that calculates and manages the actual compression ratio through software algorithms. The control apparatus uses sensor data and pre-stored maps to determine optimal mechanical compression ratio settings, substituting physical complexity with computational control while maintaining combustion stability
Data Source
AI summary
A control pattern corresponding to a ultra high expansion cycle is executed, wherein an actual timing IVCa of an intake valve closing timing is controlled to agree with a steady adapted value IVCt, an actual value εma of a mechanical compression ratio is controlled to agree with a steady adapted value εmt, and an ignition timing SA is controlled to agree with a steady adapted timing SAt. There are four cases that might be generated, including a case in which the IVCa is shifted toward a retard angle side or toward an advance angle side from the IVCt due to a response delay of a variable intake valve timing apparatus, and a case in which εma is shifted to a greater side or to a smaller side from the εmt due to the response delay of a variable compression ratio mechanism.