Engine Fuel Injection Control for Cutoff Duration
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Solution Overview
Problem
The existing control devices for internal combustion engines prolong the period of increased fuel injection amount correction after a fuel-supply cutoff process, leading to an excessively lean air-fuel ratio due to residual air and unburned fuel, especially when the fuel-supply cutoff duration is long.
Innovation Solution
A control device with an electronic control unit that calculates a base injection amount based on air intake and adjusts the increase ratio and decrease rate of fuel injection, setting a higher increase ratio and decrease rate for longer fuel-supply cutoff durations to prevent unnecessary prolongation of the correction period, using an increase coefficient and attenuation coefficient to exponentially decrease the fuel injection correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the increase ratio for fuel injection amount is set to a high value due to long duration of fuel-supply cutoff process, then the air-fuel ratio is improved to prevent excessive leanness, but the period during which fuel injection amount is corrected to be increased becomes unnecessarily long
Solution Approach 1:
The patent applies dynamics by making the decrease rate of the increase ratio variable rather than constant. The control device dynamically adjusts the decrease rate based on the duration of the fuel-supply cutoff process, using a higher decrease rate for longer durations and a lower decrease rate for shorter durations. This dynamic adjustment allows the system to quickly resolve the air-fuel ratio issue after long cutoffs while avoiding unnecessarily long correction periods for shorter cutoffs.
Solution Approach 2:
The patent changes the parameter of the decrease rate based on the fuel-supply cutoff duration. By setting different decrease rates corresponding to different cutoff durations, the system optimizes the correction period length. This parameter change approach allows the increase ratio to be reduced more quickly after long cutoffs (preventing excessive leanness) while maintaining appropriate correction periods for shorter cutoffs.
2Stability of the object's composition
If the increase ratio for fuel injection amount is gradually decreased at a prescribed rate, then the air-fuel ratio transitions smoothly, but the transition period becomes excessively long when the initial increase ratio is high
Solution Approach 1:
The patent makes the decrease rate dynamic by linking it to the fuel-supply cutoff duration. Instead of using a fixed prescribed rate, the system selects from multiple decrease rates based on the cutoff duration, creating a dynamic transition process that adapts to the specific operating condition.
Solution Approach 2:
The patent changes the transition characteristics by adjusting the decrease rate parameter according to cutoff duration. For long cutoffs, a higher decrease rate provides faster stabilization; for short cutoffs, a lower decrease rate provides smoother transition. This parameter adaptation resolves the contradiction between transition smoothness and transition speed.
Data Source
AI summary
In a control device for an internal combustion engine, when a fuel-supply cutoff process ends and fuel injection restarts, an increase ratio based on which a base injection amount is increased is set such that the increase ratio when a duration of the fuel-supply cutoff process is long is higher than the increase ratio when a duration of the fuel-supply cutoff process is short. In addition, the increase ratio is decreased with a lapse of time after fuel injection restarts. Further, a decrease rate that is an amount by which the increase ratio is decreased within a prescribed period of time is set such that the decrease rate in the case where the duration of the fuel-supply cutoff process is long is higher than the decrease rate in the case where the duration of the fuel-supply cutoff process is short.