Split Injection Control for Engine Fuel Linearity
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Solution Overview
Problem
Fuel injection control systems for cylinder injection type engines face challenges in maintaining accuracy and reducing variation in fuel injection amounts, especially at low engine loads, due to non-linear changing characteristics and the inability to correct injection control characteristics under varying operation conditions.
Innovation Solution
A fuel injection control device that employs split injection techniques, separating fuel injection into fixed and variable injections, with the first means setting injection amounts in low and high ranges, and the second and third means adjusting the variable injection based on engine load changes and actual air-fuel ratio detection before and after load variations to correct the injection control characteristic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a fuel injection valve of cylinder injection type is used to inject large amount of fuel in short period at high load, then the injection capability is improved, but the linearity of changing characteristic of actual injection amount becomes worse in low range
Solution Approach 1:
The patent divides the fuel injection process into two separate injections: a base injection with a predetermined injection period and a supplementary injection with an adjustable injection period. This segmentation allows the base injection to operate in the linear high-range region while the supplementary injection compensates for deviations in the low-range region, thereby resolving the contradiction between maintaining high injection capability and improving linearity at low injection amounts.
2Reliability
If split injection is performed and correction is based on difference between target air-fuel ratio and actual air-fuel ratio, then the variation in fuel injection amount is reduced, but the accuracy of correction becomes low when difference is generated by other factors
Solution Approach 1:
The patent extracts and isolates the injection period as a separate correction parameter from the air-fuel ratio difference. Instead of directly correcting based on air-fuel ratio deviation (which may be influenced by multiple factors), the system specifically adjusts the supplementary injection period based on the detected injection amount deviation, thereby improving correction accuracy by focusing on the controllable injection parameter rather than the composite air-fuel ratio outcome.
3Adaptability or versatility
If fuel injection is performed by switching normal injection and split injection, then the system can adapt to different conditions, but when operation condition changes during correction time, it is impossible to perform correction and predetermined frequency cannot be secured
Solution Approach 1:
The patent performs correction calculations in advance during stable operation periods before conditions change. By continuously monitoring operation conditions and pre-calculating correction values when conditions are stable, the system ensures that correction data is ready and can be applied immediately when switching between injection modes, thereby maintaining the predetermined correction frequency even during transitions.
Data Source
AI summary
A fuel injection control device for an engine executes a split injection constructed by a fixed injection and a variable injection. A required injection amount of the fixed injection is set in a low range. A required injection amount of the variable injection is set in a high range. An injection amount in the high range is larger than that of the low range. The required injection amount of the variable injection is changed within the high range while the required injection amount of the fixed injection is fixed when a load of the engine is varied while the split injection is performed. An injection control characteristic is corrected based on an actual air-fuel ratio detected before the load is varied and an actual air-fuel ratio detected after the load is varied.