Dual CVVD Engine Control for GPF Regeneration
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Solution Overview
Problem
Gasoline engines face challenges in maintaining high exhaust gas temperatures and oxygen concentrations necessary for effective soot combustion in gasoline particulate filters (GPFs), leading to soot accumulation and potential filter damage due to low-speed driving conditions.
Innovation Solution
An engine control method using a dual continuously variable valve duration device adjusts exhaust duration to increase exhaust gas temperature by retarding exhaust valve opening and advancing closing timing, maintaining a negative valve overlap, and controlling ignition timing to force GPF regeneration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the exhaust gas temperature is increased to promote soot combustion in the GPF, then the regeneration efficiency is improved, but the fuel consumption increases and combustion stability may deteriorate
Solution Approach 1:
The patent implements dynamic adjustment of exhaust valve timing based on real-time detection of soot accumulation level in the GPF. The control ECU varies the exhaust valve opening timing and duration according to the detected soot amount, enabling the exhaust gas temperature to be dynamically optimized for soot combustion while preventing excessive fuel consumption and maintaining combustion stability under varying engine operating conditions
Solution Approach 2:
The patent changes the timing parameter of the exhaust valve opening as a control variable to regulate exhaust gas temperature. By adjusting the exhaust valve opening timing relative to the piston position and engine speed, the system modifies the exhaust gas flow characteristics and temperature to create optimal conditions for soot combustion in the GPF without requiring excessive fuel injection
2Temperature
If the exhaust valve opening timing is retarded to increase exhaust gas temperature, then the GPF regeneration is promoted, but the engine power output may decrease
Solution Approach 1:
The system dynamically adjusts the exhaust valve timing based on detected engine operating conditions including engine speed, load, and soot accumulation level. The control ECU selects optimal exhaust valve opening timing from multiple possible timing patterns, enabling the system to maintain engine power output under normal operating conditions while switching to power-preserving timing patterns when GPF regeneration is required
Solution Approach 2:
The patent implements periodic GPF regeneration cycles based on detected soot accumulation levels. The exhaust valve timing is adjusted in a periodic manner to create temperature conditions favorable for soot combustion, while the control system schedules these timing adjustments to occur during appropriate engine operating cycles, thereby maintaining overall engine power output while enabling effective GPF regeneration
3Device complexity
If the valve duration is fixed to simplify the valve control mechanism, then the device complexity is reduced, but the ability to optimize valve operation for different engine speeds and loads is limited
Solution Approach 1:
The patent implements a continuously variable valve duration mechanism that dynamically adjusts the valve opening duration based on engine speed and load conditions. The valve duration is varied continuously rather than in discrete steps, allowing optimal valve operation across the entire engine operating range. This dynamic adjustment capability enables the system to adapt valve timing to different driving conditions while maintaining a relatively simple mechanical structure
Solution Approach 2:
The valve control mechanism is designed to perform multiple functions: it provides continuous variable duration control for optimizing engine performance, enables specific timing patterns for GPF regeneration, and adapts to various engine operating conditions. This multi-functionality is achieved through a unified valve control system that can generate different timing patterns without requiring separate mechanical mechanisms for each function
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 enhances exhaust gas temperature, reduces emissions, and accelerates GPF regeneration, minimizing soot accumulation and filter damage while maintaining fuel efficiency and combustion stability.
Implementation Method 1
adjusts exhaust duration to increase exhaust gas temperature by retarding exhaust valve opening and advancing closing timing, maintaining a negative valve overlap
Implementation Method 2
controlling ignition timing to force GPF regeneration
Implementation Method 3
Combustion of soot deposited in the filter is closely related to an exhaust gas temperature
Implementation Method 4
the higher the exhaust gas temperature and the higher oxygen concentration, increase the exhaust gas combustion speed
Data Source
AI summary
An engine control system is provided with a dual continuously variable valve duration (CVVD) device to optimize engine performance. The system includes an engine with a combustion chamber, an intake valve for selectively supplying an air-fuel mixture, an ignition plug for combustion, and an exhaust valve for expelling exhaust gas. The CVVD device adjusts the intake and exhaust valve durations. A turbine positioned downstream of the engine increases exhaust pressure, followed by a warm-up catalyst to preheat the exhaust gas, and a gasoline particulate filter (GPF) to filter soot. A controller, based on vehicle driving conditions, adjusts ignition timing, intake, and exhaust durations. When lambda (λ) is 1, the controller controls exhaust duration to avoid overlap with intake valve timing by retarding exhaust valve opening and advancing exhaust valve closing, thereby maintaining a negative valve overlap period and enhancing GPF regeneration and emissions control.