Engine Control for Catalyst Warm-Up via Compression Injection
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Solution Overview
Problem
In spark ignition type gasoline engines, increasing ignition timing retard to enhance catalyst activation is hindered by combustion instability due to low in-cylinder temperatures during cold starting, which slows down catalyst warm-up and increases hydrocarbon emissions.
Innovation Solution
An internal combustion engine control apparatus that prioritizes in-cylinder temperature raising using variable valve timing mechanisms to create a Negative Valve Overlap period, followed by increased ignition timing retard, thereby enhancing combustion stability and accelerating catalyst warm-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If ignition timing is retarded to raise exhaust temperature for catalyst activation, then catalyst warm-up is accelerated, but combustion stability is deteriorated due to low in-cylinder temperature during cold starting
Solution Approach 1:
The patent applies preliminary action by performing compression-stroke fuel injection before ignition to pre-heat the in-cylinder temperature. This preliminary heating action enables subsequent large ignition timing retard to be implemented without causing combustion instability, as the fuel is injected during compression stroke when the cylinder temperature is already elevated, creating favorable conditions for both stable combustion and high exhaust temperature
Solution Approach 2:
The patent segments the fuel injection process into specific phases: compression-stroke injection separate from normal intake-stroke injection. This segmentation allows the fuel to be injected at a specific moment when in-cylinder temperature is optimal, decoupling the fuel delivery timing from the ignition timing retard strategy and enabling independent optimization of both combustion stability and exhaust temperature
2Productivity
If large ignition timing retard is applied immediately after cold starting, then exhaust temperature increases for catalyst activation, but combustion instability occurs due to low in-cylinder temperature
Solution Approach 1:
The compression-stroke fuel injection serves as a preliminary action that prepares the in-cylinder environment before ignition. By injecting fuel during the compression stroke when the cylinder is already warming up, the system creates optimal conditions for immediate large ignition timing retard without compromising combustion reliability, thus enabling fast catalyst activation from cold start
Solution Approach 2:
The patent changes the fuel injection timing parameter from the conventional intake-stroke timing to compression-stroke timing. This parameter change fundamentally alters the thermal and chemical state of the fuel-air mixture at injection time, enabling the system to tolerate larger ignition timing retard values while maintaining stable combustion and achieving rapid catalyst activation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach secures combustion stability, increases the ignition timing retard amount, reduces catalyst warm-up time, and decreases hydrocarbon emissions by raising exhaust temperatures and optimizing heat transfer.
Implementation Method 1
a fuel is injected into a cylinder in a compression stroke
Implementation Method 2
a spark ignition type gasoline engine that directly injects fuel into a cylinder
Implementation Method 3
activation of a catalyst is accelerated to reduce unburned hydrocarbon
Data Source
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AI summary
Because an in-cylinder temperature becomes low immediately after cold starting, it is impossible to take large ignition timing retard to avoid combustion instability and it takes time to activate a catalyst existing downstream of an internal combustion engine. The present invention provides an internal combustion engine control apparatus including an ignition timing control unit to control an ignition timing of an ignition device attached to an internal combustion engine. The internal combustion engine control apparatus includes an in-cylinder temperature raising unit that raises an in-cylinder temperature, the in-cylinder temperature is raised by the in-cylinder temperature raising unit, and a retard amount of the ignition timing of the ignition device is increased by the ignition timing control unit.