Individual-Cylinder Torque Control for Retarded-Ignition Misfire Detection
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Solution Overview
Problem
Existing control devices for internal combustion engines struggle to accurately determine misfires when ignition timing is retarded, leading to variations in combustion torques and engine vibrations.
Innovation Solution
A control device that adjusts fuel injection amounts for individual cylinders to equalize combustion torques and incorporates a misfire determination unit to correct determination thresholds based on combustion torque and rotational speed variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If ignition timing is retarded to warm up the catalytic device, then the catalytic device temperature increases, but combustion becomes unstable causing variation in crankshaft rotational speeds
Solution Approach 1:
The control device adjusts fuel injection amounts individually for each cylinder based on its specific combustion torque characteristics. By treating each cylinder locally rather than uniformly, the system compensates for combustion instability caused by retarded ignition timing, reducing crankshaft rotational speed variation while maintaining the temperature increase needed for catalyst warm-up.
Solution Approach 2:
The system changes the fuel injection amount parameter dynamically based on detected combustion torque variations. When ignition timing is retarded for catalyst warm-up, the control device increases fuel injection amounts in cylinders experiencing combustion instability, thereby stabilizing combustion without compromising the temperature rise required for catalytic converter activation.
2Stability of the object's composition
If fuel injection amounts are adjusted to equalize combustion torques, then crankshaft rotational speed variation is reduced, but misfire detection accuracy deteriorates
Solution Approach 1:
The control device segments the combustion cycle analysis by detecting combustion torque for each individual cylinder separately and comparing it against predetermined thresholds. This segmentation allows the system to identify misfires at the cylinder level rather than averaging across all cylinders, maintaining detection accuracy even when fuel injection amounts are adjusted to equalize overall combustion torques.
Solution Approach 2:
The system implements feedback by continuously monitoring combustion torque variations and using this information for dual purposes: adjusting fuel injection amounts to stabilize crankshaft rotational speed and simultaneously detecting misfires by comparing detected torque against thresholds. The feedback loop maintains both stability improvement and detection accuracy through iterative correction.
3Object-generated harmful factors
If ignition timing is retarded for GPF regeneration, then particulate matter is burned off, but engine output decreases
Solution Approach 1:
The control device applies local quality by adjusting fuel injection amounts specifically in cylinders where combustion torque falls below the predetermined threshold during GPF regeneration. Rather than uniformly reducing engine output across all cylinders, the system selectively compensates for underperforming cylinders, maintaining overall engine power while enabling PM burn-off through retarded ignition timing.
Solution Approach 2:
The system converts the harmful effect of retarded ignition timing (reduced engine output) into a beneficial outcome (GPF regeneration). By detecting combustion torque variations and compensating through increased fuel injection in affected cylinders, the control device transforms the power loss into an opportunity for particulate matter removal, ultimately improving engine performance and emissions.
Data Source
AI summary
A control device for an internal combustion engine capable of performing ignition retardation control in which an ignition timing for igniting an air-fuel mixture in a combustion chamber is retarded from a normal operation. The device includes: an individual cylinder torque calculation unit that obtains a variation amount of combustion torque of each cylinder; an injection amount correction unit that corrects a fuel injection amount for each cylinder so as to reduce the variation amount of combustion torque of each cylinder obtained by the individual cylinder torque calculation unit; and a misfire determination unit that determines a misfire of a predetermined cylinder based on a combustion torque of the predetermined cylinder among the cylinders. When the combustion torque of any one of the cylinders is equal to or less than a predetermined torque, the injection amount correction unit does not correct the fuel injection amount for each cylinder.