Ignition Timing Control for Cold Start Combustion Stability
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Solution Overview
Problem
Existing ignition timing correction methods for internal combustion engines during cold starts can worsen combustion stability at very low water temperatures, leading to idle roughness, while setting large retard amounts at higher temperatures may not adequately promote exhaust gas temperature rise for catalyst activation.
Innovation Solution
An ignition timing control device that adjusts the retard amount based on the startup-timing water temperature, setting it higher when the temperature is lower than a predetermined value and lower when it is higher, ensuring stable combustion and effective exhaust gas temperature rise for catalyst activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the retard amount and retard-correcting period are enlarged to promote catalyst activation, then the exhaust gas temperature rises and catalyst activation is promoted, but combustion stability deteriorates and idle roughness occurs at very low water temperatures
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the ignition timing retard amount based on water temperature parameters. The ECU calculates different retard amounts according to the detected water temperature, using larger retard amounts at higher temperatures to promote catalyst activation while using smaller or zero retard amounts at very low temperatures to maintain combustion stability and prevent idle roughness.
2Temperature
If the retard amount is set at large values to promote catalyst activation, then the exhaust gas temperature rises, but drivability deteriorates due to generation of idle roughness
Solution Approach 1:
The patent changes the retard amount parameter dynamically based on water temperature conditions. At very low water temperatures, the retard amount is set to zero or small values to maintain smooth idle operation and favorable drivability. At higher water temperatures where combustion is more stable, larger retard amounts are applied to promote catalyst activation, thus optimizing drivability across different operating conditions.
3Stability of the object's composition
If the retard amount is set at small values to maintain combustion stability, then combustion stability is maintained, but the exhaust gas temperature rise effect is insufficient for catalyst activation
Solution Approach 1:
The patent applies parameter changes by adjusting the ignition timing retard amount according to water temperature. At higher water temperatures where combustion stability is sufficient, larger retard amounts are applied to achieve the necessary exhaust gas temperature rise for catalyst activation. At very low water temperatures, smaller or zero retard amounts are used to maintain combustion stability, accepting that catalyst activation will be slower under these extreme conditions.
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
This approach improves combustion stability and exhaust performance by optimizing the retard amount according to the water temperature, preventing idle roughness and ensuring quick catalyst activation without excessive drivability or fuel economy impacts.
Implementation Method 1
a spark plug 14 configured to ignite an air-fuel mixture in a combustion chamber
Implementation Method 2
a catalyst 10 interposed in an exhaust passage 5 of the internal combustion engine 1 and configured to purify an exhaust gas flowing in the exhaust passage 5
Implementation Method 3
heat transmitted from combustion gas to an engine block and heat transmitted from the engine block to cooling water
Data Source
Figure 1
Figure 2
Figure 3(A)~3(C)
AI summary
A water temperature indicated at a startup timing of an engine is stored as a startup-timing water temperature. During an idling state generated after a cold start, a retard amount (S) is calculated based on the startup-timing water temperature. At this time, the retard amount (S) is set at a larger level as the startup-timing water temperature becomes higher. However, in a case that the startup-timing water temperature is higher than a predetermined temperature, the retard amount (S) is set at a smaller level as the startup-timing water temperature becomes higher. A retard amount (R) is calculated based on a current water temperature in the same manner as the retard amount (S). A smaller one is selected from the retard amount (S) and the retard amount (R), as a basic retard amount.