SIDI Engine Cold Start Control via Fuel Prime Pulse Injection
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Solution Overview
Problem
Spark ignition direct injection (SIDI) engines face challenges in starting at cold temperatures due to insufficient fuel delivery from conventional fuel pumps and injectors, which can increase engine costs and worsen fuel injection control at low pulse widths.
Innovation Solution
A control system and method that determines predetermined operating conditions to enable an engine prime mode, allowing a fuel injector to deliver a prime pulse to the engine cylinders before cranking, improving fuel wetting and combustion likelihood at cold temperatures, without the need for high-capacity fuel pumps and injectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fuel pump and fuel injectors with larger capacities are used to meet cold start fuel demands, then cold startability is improved, but engine cost increases and fuel injection control at low pulse widths worsens
Solution Approach 1:
The system performs preliminary fuel injection action by delivering a prime pulse to the cylinder before engine cranking when cold start conditions are detected. This advance fuel delivery ensures adequate fuel is present in the combustion chamber before combustion begins, resolving the cold startability issue without requiring oversized fuel delivery components.
Solution Approach 2:
The control system changes the injection timing parameter by injecting fuel before cranking (negative camshaft position timing) rather than during or after cranking. This parameter change allows the existing fuel system to deliver adequate fuel for cold starts by optimizing when the injection occurs, not by increasing system capacity.
2Device complexity
If conventional fuel pumps and injectors are used for SIDI engines, then device complexity is reduced, but cold start fuel delivery is insufficient
Solution Approach 1:
The control system commands the fuel injector to deliver a prime pulse before engine cranking when cold start conditions are detected. This preliminary fuel delivery ensures adequate fuel quantity is present in the cylinder before combustion begins, allowing conventional fuel system components to meet cold start demands.
Solution Approach 2:
The system uses the existing fuel injector hardware designed for normal operation to perform an additional preliminary injection function. By reusing the conventional injector for both normal injection and cold start prime pulse delivery, the system avoids needing separate high-capacity fuel delivery components.
3Productivity
If fuel is injected at high pressure directly into combustion chambers, then combustion efficiency is improved, but cold start fuel delivery control becomes difficult
Solution Approach 1:
The control system performs preliminary fuel injection before cranking when the engine is stationary and conditions are stable. This timing allows precise control of the prime pulse delivery to ensure adequate fuel is present in the cylinder before combustion begins, maintaining control ease while achieving good combustion efficiency.
Solution Approach 2:
The system changes the injection timing parameter to occur before cranking (negative camshaft position) rather than during operation. This parameter change simplifies control by injecting fuel when the engine is stationary and conditions are stable, avoiding the complexity of controlling high-pressure injection during dynamic cold start conditions.
Data Source
AI summary
A control system includes an engine enable module and a fuel control module. The engine enable module determines whether predetermined operating conditions of a spark ignition direct injection (SIDI) engine are satisfied and enables an engine prime mode when the predetermined operating conditions are satisfied. The fuel control module controls a fuel injector to deliver a prime pulse to a cylinder of the SIDI engine when the engine prime mode is enabled. The fuel injector delivers the prime pulse by opening for a pulse width to inject fuel directly into the cylinder when the SIDI engine is stopped.