Engine Controller Combustion Air-Fuel Ratio Estimation
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Solution Overview
Problem
Existing engine controllers struggle to precisely control the air-fuel ratio at engine start, leading to inefficient exhaust emission control and unstable engine operation, particularly due to low fuel vaporization rates and uneven air-fuel ratio distribution across cylinders.
Innovation Solution
An engine controller that includes combustion state detection and estimation means, using exhaust air-fuel ratio feedback and additional parameters like engine revolutions, intra-cylinder pressure, and torque to accurately estimate the combustion air-fuel ratio, allowing for precise control of fuel injection and ignition timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If exhaust air-fuel ratio feedback control is initiated at a fixed time after start, then the control system is simple and easy to operate, but the combustion air-fuel ratio cannot be precisely controlled at engine start
Solution Approach 1:
The patent implements feedback control by continuously monitoring exhaust air-fuel ratio and using it to adjust fuel injection amount. The controller compares detected exhaust air-fuel ratio with target values and dynamically corrects fuel injection to maintain precise combustion air-fuel ratio control during engine start and warm-up phases.
Solution Approach 2:
The patent initiates exhaust air-fuel ratio feedback control at engine start rather than waiting for a fixed time delay. By starting control immediately and progressively adjusting based on engine temperature and operating conditions, the system achieves precise air-fuel ratio control from the beginning while adapting to changing combustion characteristics during warm-up.
2Measurement precision
If air-fuel ratio sensor is activated early with preheat system, then exhaust air-fuel ratio feedback control can be initiated at start, but fuel vaporization is incomplete at low temperature causing inaccurate measurements
Solution Approach 1:
The patent dynamically changes control parameters including fuel injection amount, ignition timing, and feedback control activation timing based on engine temperature and operating conditions. By adjusting these parameters progressively during warm-up, the system ensures complete fuel vaporization and accurate exhaust air-fuel ratio measurements while maintaining reliable combustion control.
Solution Approach 2:
The patent uses engine temperature and operating condition parameters as intermediaries to mediate between the need for early feedback control initiation and the requirement for complete fuel vaporization. These intermediary parameters allow the system to progressively enable feedback control only when combustion conditions are sufficient for accurate measurements.
3Reliability
If lower fuel correction limit is restricted according to exhaust air-fuel ratio feedback, then excessively lean burn is prevented, but combustion air-fuel ratio cannot be controlled to appropriate value and lean firemiss risk increases
Solution Approach 1:
The patent implements dynamic adjustment of fuel correction limits based on real-time exhaust air-fuel ratio feedback and engine operating conditions. Rather than using fixed lower limits, the system continuously adapts the correction range to match actual combustion characteristics, preventing both excessively lean burn and lean firemiss while maintaining precise air-fuel ratio control.
Solution Approach 2:
The patent uses exhaust air-fuel ratio feedback to dynamically determine appropriate fuel correction limits. The controller continuously monitors exhaust air-fuel ratio and adjusts fuel injection correction limits in real-time, ensuring that the combustion air-fuel ratio is maintained within optimal ranges without risking lean firemiss or excessive leaning.
4Measurement precision
If air-fuel ratio sensor is attached for each cylinder, then combustion air-fuel ratio can be directly detected with high precision, but system cost increases significantly
Solution Approach 1:
The patent merges the air-fuel ratio measurement function from individual cylinder sensors to a single exhaust air-fuel ratio sensor that measures the combined exhaust from all cylinders. By combining measurements and using feedback control to regulate total fuel injection, the system achieves effective air-fuel ratio control without the complexity and cost of multiple sensors.
Solution Approach 2:
The patent uses exhaust air-fuel ratio as a representative copy that reflects the overall combustion air-fuel ratio across all cylinders. Rather than directly measuring each cylinder's combustion air-fuel ratio, the system uses the exhaust measurement as a proxy and applies feedback control to maintain accurate overall combustion control.
Data Source
AI summary
An engine controller comprises a combustion state detection or estimation means for detecting or estimating a combustion state in the combustion chamber, a combustion air-fuel ratio estimation means for estimating a combustion air-fuel ratio in the combustion chamber according to an exhaust air-fuel ratio and the detected or estimated combustion state, and a means for calculating engine control parameters according to the estimated combustion air-fuel ratio.