Engine Control Apparatus EGR-Dependent Ignition Timing Correction
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Solution Overview
Problem
Existing internal combustion engine control systems with exhaust gas recirculation devices do not adequately account for the presence and amount of EGR gas when adjusting ignition timing based on intake air temperature, leading to inefficiencies in torque and fuel consumption.
Innovation Solution
A control apparatus and method that calculates a retardation amount for ignition timing based on intake air temperature, coolant temperature, and oil temperature, with separate maps for when the exhaust gas recirculation device is on or off, to optimize ignition timing correction and enhance torque and fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the correction amount regarding intake air temperature is increased as intake air temperature rises, then combustion speed is improved, but the influence of EGR gas amount on ignition timing correction is not considered leading to suboptimal torque and fuel consumption
Solution Approach 1:
The patent applies parameter changes by introducing a dual-map correction system where the intake air temperature correction map is selected based on the EGR valve opening degree. When EGR is active (EGR valve opening degree ≥ threshold), a first correction map is used; when EGR is inactive, a second correction map is used. This allows the correction amount to dynamically adapt to both temperature and EGR conditions, optimizing both combustion speed and overall engine efficiency.
Solution Approach 2:
The system dynamically switches between different correction maps based on the EGR valve opening degree. The calculation portion determines whether EGR is present by comparing the EGR valve opening degree against a threshold, then selects the appropriate correction map accordingly. This dynamic adaptation ensures that the ignition timing correction accurately reflects the actual combustion conditions whether EGR is active or inactive.
2Speed
If the base ignition timing is advanced as EGR amount increases to compensate for decreased combustion speed, then combustion speed is maintained, but the interaction between EGR amount and intake air temperature on ignition timing is not optimized
Solution Approach 1:
The patent changes the parameter of ignition timing correction by introducing EGR-dependent correction maps. Instead of using a single correction amount for all conditions, the system selects different correction maps based on EGR valve opening degree. This allows the correction to account for the interaction between EGR amount and intake air temperature, optimizing both combustion speed and engine productivity simultaneously.
Solution Approach 2:
The patent applies local quality by providing different correction characteristics for different EGR conditions. The first correction map (for EGR active conditions) and second correction map (for EGR inactive conditions) have different local characteristics tailored to their respective operating conditions. This localized optimization ensures that each operating regime receives the most appropriate correction for its specific conditions.
Data Source
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AI summary
When EGR is on (YES in SlOO), an ECU selects a first map for the time when EGR is on as an intake air temperature correction map (S 102). Thus, an intake air temperature correction retardation amount a is set to an intake air temperature correction retardation amount aon (THa, KL) for the time when EGR is on, which corresponds to an intake air temperature THa and an engine load KL. On the other hand, when EGR is off (NO in SlOO), the ECU selects a second map for the time when EGR is off as an intake air temperature correction map (S 104). Thus, the intake air temperature correction retardation amount a is set to an intake air temperature correction retardation amount aoff (THa, KL) for the time when EGR is off, which corresponds to the intake air temperature THa and the engine load KL.