SIDI Cold Start Strategy Using High Pressure Fuel Injection
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Solution Overview
Problem
Conventional spark-ignition direct-injection (SIDI) engine control systems face challenges in reducing hydrocarbon emissions during cold starts due to low fuel pressure, which limits fuel injection timing and increases emissions.
Innovation Solution
The engine control system delays fuel injection until high fuel pressure is reached and retards ignition timing and exhaust cam phaser after oil pressure exceeds a threshold, using high pressure fuel near top dead center to reduce emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If fuel injection is delayed until high fuel pressure is reached during engine cranking, then hydrocarbon emissions are reduced, but engine starting time is extended
Solution Approach 1:
The fuel pump is activated before engine cranking to pre-pressurize the fuel system, ensuring high fuel pressure is available when injection is needed. This preliminary action prevents the delay caused by waiting for pressure buildup during cranking, thus reducing emissions without extending starting time
2Object-generated harmful factors
If ignition timing is retarded during engine cranking, then hydrocarbon emissions are reduced, but combustion efficiency decreases
Solution Approach 1:
The ignition timing is dynamically adjusted based on engine operating conditions: retarded during cranking to reduce emissions, then progressively advanced as the engine stabilizes to optimize combustion efficiency. This dynamic adjustment resolves the contradiction by adapting timing to the engine's operational state
3Object-generated harmful factors
If exhaust cam phaser is retarded after starting, then hydrocarbon emissions are reduced, but engine power output decreases
Solution Approach 1:
The exhaust cam phaser is dynamically controlled to be retarded after engine starting to reduce hydrocarbon emissions, then progressively returned to its optimal position as the engine warms up and operating conditions stabilize, thereby minimizing the impact on power output while achieving emission reductions during the critical cold start period
Data Source
AI summary
An engine control system for a spark-ignition direct-injection (SIDI) engine comprises a fuel control module delays injection of fuel during engine cranking until fuel pressure is greater than a predetermined fuel pressure, retards ignition timing, and retards fuel injection until near top dead center (TDC). An exhaust cam phaser module retards an exhaust cam phaser after starting and oil pressure is greater than a predetermined oil pressure.