Engine Misfire Avoidance via Ignition Timing Control
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Solution Overview
Problem
Internal combustion engines with EGR devices face misfires due to excessive EGR gas during deceleration and re-acceleration, leading to inefficient fuel consumption and inadequate misfire avoidance despite existing control measures.
Innovation Solution
A control device that delays ignition timing and executes misfire avoidance control by estimating cylinder-inflow EGR gas amount, predicting misfire occurrence, and restricting ignition timing delay when necessary, thereby maintaining fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If ignition timing is delayed to decrease torque during deceleration, then fuel consumption is improved, but misfire limit decreases making misfire more likely
Solution Approach 1:
The system dynamically changes ignition timing parameters based on operating conditions. During deceleration, ignition timing is delayed to improve fuel consumption, but when EGR gas amount exceeds thresholds, the system adjusts ignition timing parameters to prevent misfire, thus resolving the contradiction between fuel efficiency and reliability
Solution Approach 2:
The system uses feedback from EGR gas amount detection and misfire occurrence patterns to continuously adjust ignition timing. When misfire is predicted based on accumulated EGR gas, the ignition timing control is modified in real-time to maintain reliable combustion while preserving fuel efficiency benefits
2Reliability
If EGR gas amount is decreased to avoid misfire, then misfire is prevented, but fuel efficiency benefits from EGR gas are lost
Solution Approach 1:
The system dynamically controls EGR valve opening degree based on real-time operating conditions and accumulated EGR gas amounts. Rather than maintaining a fixed EGR rate, the control system adjusts EGR gas recirculation dynamically to prevent misfire while maximizing fuel efficiency benefits during appropriate operating conditions
Solution Approach 2:
The system changes EGR gas amount parameters dynamically based on accumulated EGR gas thresholds and ignition timing delay amounts. When thresholds are exceeded, EGR gas amount is adjusted to prevent misfire; otherwise, optimal EGR rates are maintained for fuel efficiency
3Reliability
If misfire avoidance control is executed during deceleration, then misfire is avoided, but the control effectiveness is insufficient when ignition timing is heavily delayed
Solution Approach 1:
The system performs preliminary detection and accumulation of EGR gas amounts before misfire actually occurs. By monitoring EGR gas buildup in advance and predicting misfire risk based on accumulated amounts, the system can take preventive action on ignition timing and EGR control before combustion failure happens, ensuring effective misfire avoidance even during heavy ignition timing delays
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively prevents misfires during deceleration and re-acceleration while maintaining fuel efficiency by accurately predicting and addressing EGR gas-related combustion issues without reducing EGR gas amounts.
Implementation Method 1
an EGR device that recirculates, as EGR gas, a portion of exhaust gas of the internal combustion engine to an intake passage
Implementation Method 2
internal combustion engine
Data Source
AI summary
A cylinder-inflow EGR gas amount is estimated, a misfire limit EGR gas amount is calculated on the basis of an engine operation state, and the misfire limit EGR gas amount is compared with the cylinder-inflow EGR gas amount to predict whether a misfire occurs. When the misfire is predicted, a misfire avoidance control is executed. Further, an actual misfire countermeasure effect amount in a case of the execution of the misfire avoidance control is calculated, and the actual misfire countermeasure effect amount is compared with a required misfire countermeasure effect amount to determine whether the misfire is avoidable when the misfire avoidance control is executed. If the misfire is unavoidable even if the misfire avoidance control is executed, a delay restriction value of an ignition timing to avoid the misfire is calculated, and the amount of a delay in the ignition timing is restricted using the delay restriction value.