Fuel Injection Delay Control for Variable Displacement Engines
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Solution Overview
Problem
Variable displacement engines face challenges in accurately determining fuel injection delay due to cylinder deactivation, leading to air-fuel ratio oscillations and reduced engine efficiency, as existing methods rely on a single delay value that is no longer appropriate with varying cylinder activation patterns.
Innovation Solution
A method that calculates fuel injection delay using a weighted average of past and present engine cycles, incorporating a base delay time and extra delay time based on expected cylinder deactivation patterns, allowing for improved estimation and control regardless of known future cylinder firing patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single fuel injection delay value is used for all engine cycles, then the control system is simple, but air-fuel ratio oscillations occur due to cylinder deactivation patterns
Solution Approach 1:
The fuel injection delay value is made dynamic by calculating it as a weighted average between a base delay value and an extra delay value. The extra delay value is determined based on the current cylinder deactivation pattern, allowing the delay compensation to adapt to varying engine operating conditions while maintaining a relatively simple control structure.
2Speed
If the control gain is increased to reduce error quickly, then response time improves, but air-fuel ratio oscillations are induced
Solution Approach 1:
The controller calculates the fuel injection delay compensation value in advance based on the expected cylinder deactivation pattern before the actual fuel injection occurs. By determining the appropriate delay compensation beforehand, the controller can apply higher gains for faster error correction without inducing oscillations, as the timing of fuel injection is already optimized for the current operating conditions.
3Measurement precision
If fuel injection timing is adjusted to compensate for delay, then air-fuel ratio control accuracy improves, but complexity increases due to varying cylinder patterns
Solution Approach 1:
The fuel injection delay compensation is segmented into two distinct components: a base delay value that applies to all engine cycles, and an extra delay value that is specific to the current cylinder deactivation pattern. This segmentation allows the control algorithm to maintain accuracy by accounting for pattern-specific variations while keeping the overall structure manageable through modular calculation.
Data Source
AI summary
Systems and methods for determining fuel delay in a fuel injected engine with cylinders that may be deactivated are presented. In one example, the fuel injection delay is determined via a cylinder firing schedule array when the cylinder firing schedule array is available. The fuel injection delay is determined via weighted average of a fuel injection delay of a present engine cycle and a fuel injection delay of a past engine cycle when the cylinder firing schedule array is not available.