Engine Ignition Timing Correction for Torque Stability
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Solution Overview
Problem
Existing temperature raising processes for internal combustion engines cause torque fluctuations, leading to deteriorated drivability and fuel economy, as they involve controlling cylinders to rich and lean air-fuel ratios, which result in increased rotational speed fluctuations and torque imbalances.
Innovation Solution
A control apparatus with an electronic control unit that calculates theoretical ignition timings, adjusts air-fuel ratios, and corrects ignition timings in rich and lean cylinders to manage torque fluctuations, ensuring the torque generated in each cylinder remains within optimal ranges during temperature raising processes, particularly in low-load operating states to minimize fuel consumption impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If ignition timing is corrected to be retarded in rich cylinders to restrain torque increase, then drivability is improved, but fuel economy deteriorates
Solution Approach 1:
The patent applies dynamics by making the ignition timing correction variable rather than fixed. The control unit dynamically adjusts the ignition timing correction amount based on real-time detection of torque fluctuations and engine operating conditions. This allows the system to optimize between drivability and fuel economy by adapting the correction magnitude to current engine state, rather than using a static retarding correction that would permanently sacrifice fuel efficiency.
Solution Approach 2:
The patent implements feedback by continuously monitoring torque fluctuations during temperature raising processes and using this information to adjust ignition timing corrections. The control unit detects actual torque deviations and modifies ignition timing accordingly, creating a closed-loop control system that balances the conflicting objectives of smooth operation and fuel efficiency based on real-time performance data.
2Reliability
If air-fuel ratio is controlled to rich and lean cylinders to raise catalyst temperature, then emission properties are improved, but torque fluctuations increase
Solution Approach 1:
The patent applies parameter changes by modifying ignition timing as a control variable to compensate for torque fluctuations caused by air-fuel ratio changes. When cylinders are controlled to rich or lean mixtures for catalyst temperature raising, the control unit simultaneously adjusts ignition timing parameters to counteract the resulting torque variations, thereby maintaining overall torque stability while preserving the emission benefits of the air-fuel ratio manipulation.
Solution Approach 2:
The patent uses ignition timing correction as an intermediary mechanism to mediate between the conflicting effects of air-fuel ratio control. The ignition timing adjustment acts as a compensating factor that translates the harmful torque fluctuations into manageable corrections, allowing the system to achieve both emission improvement and torque stability through coordinated control of multiple parameters.
3Ease of operation
If rotational speed is restrained from increasing during rich air-fuel ratio control, then drivability is improved, but temperature raising effectiveness decreases
Solution Approach 1:
The patent applies dynamics by making the ignition timing correction adaptive to engine operating conditions. The control unit dynamically adjusts the degree of ignition timing retardation based on detected torque fluctuations and engine state, allowing the system to optimize between rotational speed control for drivability and temperature raising effectiveness for emission control, rather than using a fixed correction that would permanently sacrifice one objective.
Data Source
AI summary
In a control apparatus for an internal combustion engine, The ignition timing in a rich-cylinder is corrected toward a retardation side from a theoretical-MBT such that the torque generated in the rich-cylinder exceeds a torque generated in the rich-cylinder at the theoretical-MBT, and the ignition timing in a lean-cylinder is corrected toward an advancement side from the theoretical-MBT such that the torque generated in the lean-cylinder exceeds a torque generated in the lean-cylinder at the theoretical-MBT, when a temperature raising process is being executed, and the ignition timing in the rich-cylinder is corrected further toward the retardation side such that the torque generated in the rich-cylinder becomes equal to or smaller than a maximum theoretical generated torque and equal to or larger than the torque generated in the lean-cylinder at the theoretical-MBT, when the temperature raising process is being executed and the engine is in a low-load operating state.