Multicylinder Engine Cylinder-Specific Control for Combustion Uniformity
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Solution Overview
Problem
Multicylinder engines face variations in combustion due to imbalances between tumble flow and fuel spray strength caused by errors in intake port shape, leading to inconsistent ignition performance across cylinders, which existing technologies struggle to correct before the engine leaves the production line.
Innovation Solution
A multicylinder engine design with electronically controlled intake ports and injectors, where each cylinder's intake port throat has a narrowed portion with varying distance from the cylinder head, and an electronic control unit sets specific control parameters like ignition timing, fuel injection pressure, and tumble flow strength to balance the air-fuel ratio uniformly across cylinders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If intake ports are formed by separate cores in casting, then manufacturing is easier, but displacement errors occur causing tumble flow imbalance among cylinders
Solution Approach 1:
The patent divides the correction task into segments: measuring the actual distance L for each cylinder's intake port throat separately, then individually adjusting the control parameter for each cylinder based on its specific measurement, rather than attempting to correct all cylinders uniformly
Solution Approach 2:
The patent changes the control parameter (ignition timing, fuel injection amount, or tumble flow production) based on the measured distance L for each cylinder. By establishing a relationship between distance L and control parameter values, the system compensates for manufacturing variations without requiring perfect manufacturing precision
2Reliability
If fuel injection timing is corrected after combustion fluctuations are detected, then combustion balance is improved, but correction time is delayed until after production line operation
Solution Approach 1:
The patent performs the critical measurement action in advance: the distance L from the intake port throat narrowed portion to the cylinder head lower surface is measured before the engine leaves the production line. This preliminary measurement enables subsequent control parameter adjustments to be made immediately, rather than waiting for operational detection of combustion fluctuations
Solution Approach 2:
The patent replaces the operational trial-and-error detection method with a direct mechanical measurement approach. Instead of running the engine and detecting combustion fluctuations to infer tumble flow issues, the system directly measures the geometric parameter L that causes the problem, enabling immediate correction
3Reliability
If tumble flow strength varies among cylinders due to intake port errors, then combustion quality deteriorates, but manufacturing variations are difficult to eliminate
Solution Approach 1:
The patent applies local quality correction by adjusting control parameters individually for each cylinder based on its specific measured distance L. Each cylinder receives a customized control parameter value tailored to its local geometric characteristics, compensating for manufacturing variations without requiring uniform high-precision manufacturing across all cylinders
Solution Approach 2:
The system enables each cylinder to self-correct its combustion performance by measuring its own distance L and applying its own specific control parameter adjustment. The engine system uses its own manufacturing variations as input data to automatically compensate for them, eliminating the need for external manual adjustment
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 ensures uniform combustion conditions across all cylinders by adjusting control parameters based on the unique geometry of each intake port, reducing variations in tumble flow strength and enhancing ignition performance from the outset, thereby minimizing combustion inconsistencies.
Implementation Method 1
each having a throat including a narrowed portion, such that tumble flow is produced in a combustion chamber of each of the cylinders
Implementation Method 2
fuel is injected from an in-cylinder injector against the tumble flow, so that the penetration force of fuel spray in the combustion chamber is controlled
Implementation Method 3
stratified charge combustion operation using fuel injection by the in-cylinder injector is performed
Data Source
AI summary
A multicylinder engine includes a plurality of intake ports, a plurality of in-cylinder injectors, and an electronic control unit. The electronic control unit is configured to initially set a value of a control parameter of the multicylinder engine, individually for each of the cylinders, such that there is a common regularity between a distribution among the cylinders, of a difference of the value of the control parameter of each of the cylinders from the value of the control parameter of a reference cylinder, and a distribution among the cylinders, of a difference of the distance of a narrowed portion of each of the cylinders from the distance of the narrowed portion of a reference cylinder. The control parameter is a parameter that determines an air-fuel ratio of an air-fuel mixture around an ignition plug at a time of ignition in stratified charge combustion operation.