Engine Control Device for Catalyst Warm-up and Emission Reduction
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Solution Overview
Problem
In cylinder direct injection type spark ignition engines, liquefied fuel accumulation on the piston crown surface during cold engine operation leads to increased exhaust gas particulate matter (PM) emissions, as existing control methods are ineffective in suppressing fuel accumulation due to differences in heating and temperature increase purposes between port injection and direct injection engines.
Innovation Solution
An engine control device that retards the ignition timing and increases the valve overlap period as the piston crown surface temperature rises, implementing a two-stage fuel injection strategy and adjusting fuel injection timing to prevent fuel accumulation, while promoting fuel vaporization through internal exhaust gas recirculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the ignition timing is retarded and valve overlap period is increased to warm up the catalyst during cold engine operation, then the catalyst warm-up efficiency is improved, but the fuel accumulation on piston crown surface increases leading to higher particulate emissions
Solution Approach 1:
The valve overlap period is made variable rather than fixed, allowing it to be dynamically adjusted based on engine operating conditions. The control device increases the valve overlap period gradually as the piston crown surface temperature increases during catalyst warm-up operation, optimizing both catalyst heating and fuel vaporization at different stages of the warm-up process
Solution Approach 2:
The ignition timing and valve overlap period are adjusted as controllable parameters to achieve optimal performance. By retarding ignition timing and dynamically changing the valve overlap period duration, the system balances catalyst warm-up efficiency with fuel vaporization to suppress particulate emissions
2Object-generated harmful factors
If the valve overlap period is increased to promote fuel vaporization on the piston crown surface, then the particulate emissions are reduced, but the combustion stability deteriorates
Solution Approach 1:
The valve overlap period is dynamically adjusted based on real-time temperature conditions. As the piston crown surface temperature increases during catalyst warm-up operation, the valve overlap period is gradually increased to promote fuel vaporization while maintaining combustion stability at each temperature stage
Solution Approach 2:
The control is implemented in stages during the catalyst warm-up operation, with the valve overlap period being periodically adjusted as temperature milestones are reached, allowing the system to adapt to changing thermal conditions while maintaining stable combustion
3Temperature
If the ignition timing is retarded to warm up the catalyst, then the exhaust gas temperature increases, but the engine torque decreases
Solution Approach 1:
The ignition timing is adjusted as a controllable parameter during catalyst warm-up operation. By retarding the ignition timing, the combustion process occurs later in the expansion stroke, increasing exhaust gas temperature for catalyst warm-up while the control device manages the trade-off with engine torque output
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 effectively reduces particulate number (PN) emissions by ensuring fuel vaporization and preventing accumulation on the piston crown surface, maintaining combustion stability and engine torque, and promoting catalyst warm-up.
Implementation Method 1
promoting fuel vaporization through internal exhaust gas recirculation
Implementation Method 2
stratified charge combustion is performed
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An engine control device controls a cylinder direct fuel injection type spark ignition engine provided with a fuel injection valve configured to directly inject fuel into a cylinder and an ignition plug configured to perform spark ignition for a gas mixture inside the cylinder. The engine control device executes a catalyst warm-up operation for retarding an ignition timing, during a compression stroke of the fuel injection timing, in a case where it is necessary to warm up an exhaust gas purifying catalyst inserted into an exhaust passage. In addition, the engine control device increases a valve overlap period as a piston crown surface temperature increases during execution of the catalyst warm-up operation.