Fuel Injection Fraction Filtering for Transient Air-Fuel Ratio Control
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Solution Overview
Problem
Fuel puddle formation and dispersal in engine cylinders due to port and direct fuel injectors lead to air-fuel ratio errors during transient engine conditions, as the mass of fuel puddles increases or decreases with engine operating conditions, necessitating a method to compensate for these changes.
Innovation Solution
Retrieving engine operating information to adjust the direct fuel injection fuel fraction, filtering this fraction, and adjusting the fuel amount injected to compensate for differences between the direct fuel injection fuel fraction and its filtered value, ensuring that the fuel proportion from both port and direct injectors remains consistent with desired engine fuel amounts despite changing puddle sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If port fuel injectors are used to supply fuel to engine cylinders, then lower engine emissions are achieved at lower engine temperatures, but fuel puddles form in cylinder intake ports leading to air-fuel ratio errors during transient conditions
Solution Approach 1:
The fuel injection system is segmented into two separate injectors: a port fuel injector that delivers port fuel injection (PFI) and a direct fuel injector that delivers direct injection (DFI). This segmentation allows each injector to operate in its optimal regime, with the PFI providing stable combustion at low temperatures and the DFI providing precise air-fuel ratio control, thereby resolving the contradiction between emission performance and air-fuel ratio precision
Solution Approach 2:
The system dynamically changes the fuel fraction parameter delivered by each injector type based on engine operating conditions. During transient conditions, the control system adjusts the DFI fraction to compensate for fuel puddle formation and dispersal, maintaining accurate air-fuel ratio control while preserving the emission benefits of PFI during steady-state operation
2Measurement precision
If direct fuel injectors are used to improve air-fuel ratio control, then vehicle emissions are improved during warm engine operating conditions, but fuel puddles form within the cylinder leading to air-fuel ratio errors during transient conditions
Solution Approach 1:
The control system continuously monitors engine operating conditions and uses feedback to dynamically adjust the direct fuel injection fraction. When fuel puddles form or disperse during transient conditions, the system detects these changes and compensates by adjusting the DFI amount, thereby maintaining reliable air-fuel ratio accuracy despite the presence of fuel puddles
Solution Approach 2:
The system transitions from a static fuel injection approach to a dynamic one where the fuel fraction from direct injectors is continuously adjusted based on real-time engine conditions. This dynamic adjustment allows the system to maintain high air-fuel ratio control precision during both steady-state and transient operations, overcoming the limitation of fixed injection strategies
3Reliability
If the direct fuel injection fuel fraction is adjusted based on engine operating conditions, then transient fuel control is improved, but the system complexity increases due to filtering and compensation requirements
Solution Approach 1:
The control system applies filtering to the direct fuel injection fraction signal in advance of the actual fuel injection event. This preliminary filtering action smooths out rapid fluctuations in the desired fuel fraction and anticipates fuel puddle behavior, allowing the system to achieve reliable transient fuel control without requiring complex real-time compensation algorithms during the injection process itself
Data Source
AI summary
Methods and systems are presented for adjusting an amount of fuel supplied to an engine via port and direct fuel injectors during transient engine operating conditions where the fuel injection amount is adjusted responsive to the transient engine operating conditions. In one example, a fuel injection amount is adjusted based on a time constant for a filter that is based on a direct fuel injection fuel fraction.