Engine Fuel Injection Control for Altitude EGR Linearity
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Solution Overview
Problem
Internal combustion engines face challenges in maintaining accuracy of fuel injection at high altitudes and varying internal exhaust gas recirculation (EGR) rates, leading to potential errors in output control due to non-linear fuel injection characteristics and difficulty in estimating EGR from atmospheric pressure.
Innovation Solution
A control device that includes a signal generator to adjust the fuel injection rate based on estimated internal EGR, using pre-turbine exhaust gas pressure as a parameter to ensure accurate fuel injection by adjusting the fuel pressure supplied to the fuel injection valve, thereby maintaining linearity between fuel injection period and amount.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the fuel injection amount is reduced to compensate for decreased pumping loss at high altitudes, then the output loss is reduced, but the fuel injection period becomes shorter and linearity between injection period and injection amount deteriorates
Solution Approach 1:
The patent changes the fuel injection rate parameter in response to changes in atmospheric pressure. Specifically, when atmospheric pressure decreases (indicating high altitude operation), the control device increases the fuel injection rate to compensate for the shortened injection period, thereby maintaining the linearity between injection period and injection amount despite the reduced total injection quantity needed for pumping loss compensation
2Productivity
If the fuel injection amount is reduced to improve combustion state by reducing internal EGR, then the combustion efficiency is improved, but the fuel injection period becomes shorter and linearity deteriorates
Solution Approach 1:
The patent adjusts the fuel injection rate parameter based on the internal EGR rate. When the internal EGR rate is low (which occurs when fuel injection amount is reduced to improve combustion), the control device increases the injection rate to maintain the linear relationship between injection period and injection amount, thus preserving injection accuracy while allowing combustion efficiency improvements
3Device complexity
If atmospheric pressure is used to estimate internal EGR rate, then the estimation is simplified, but the accuracy deteriorates because atmospheric pressure does not directly reflect internal EGR conditions
Solution Approach 1:
The patent introduces atmospheric pressure as an intermediary parameter to estimate the internal EGR rate. Although atmospheric pressure does not directly measure internal EGR, it serves as a useful proxy that correlates with operating conditions affecting EGR. The control device uses this intermediary estimation to adjust the fuel injection rate, achieving a practical balance between system simplicity and control accuracy
Data Source
AI summary
A fuel injection valve is for injecting fuel to cause combustion in an internal combustion engine. An injection rate adjuster is for adjusting an injection rate of the fuel injected by the fuel injection valve. A control device for the internal combustion engine includes a signal generator, and an outputter. The signal generator generates a command signal to cause the injection rate adjuster to adjust the injection rate based on a parameter, which is to estimate an internal EGR amount in which a part of exhaust gas remains in a cylinder. The outputter outputs the command signal to the injection rate adjuster.