Dual CVVD Engine Control for Cold Start Emission Reduction
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Solution Overview
Problem
Existing engine control systems fail to effectively reduce emissions of nitrogen oxides and hydrocarbons during the initial stages of engine operation when the three-way catalyst is not warmed up, as the catalyst's low temperature impairs its ability to purify exhaust gases efficiently.
Innovation Solution
A dual continuously variable valve duration (CVVD) system that adjusts intake and exhaust valve durations and ignition timing based on the temperature of the exhaust gas and driving conditions, utilizing a warm-up catalytic converter with a three-way catalyst, a hydrocarbon trap, and an electrically heated catalyst to minimize emissions by optimizing valve operations and catalyst activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the three-way catalyst is used without enhanced low temperature NOx purification function, then the catalyst structure is simpler, but the NOx purification efficiency at low temperature is insufficient
Solution Approach 1:
The patent applies parameter changes by modifying the catalyst's chemical composition parameters - specifically incorporating Pt/Rh or Pd/Rh catalyst systems with optimized ratios to enhance low-temperature NOx purification efficiency while maintaining structural feasibility
2Loss of time
If the exhaust gas temperature is increased rapidly during warm-up, then the catalyst activation is faster, but the emission of nitrogen oxides and hydrocarbons increases
Solution Approach 1:
The patent applies preliminary action by controlling the exhaust gas temperature and emission parameters during the warm-up phase before the catalyst reaches full activation temperature. The ECU adjusts valve durations and ignition timing to minimize emissions during this critical period when the catalyst is not yet fully active
Solution Approach 2:
The patent implements feedback control where the ECU continuously monitors exhaust gas temperature and emission levels, adjusting valve duration and ignition timing in real-time to balance catalyst activation speed with emission reduction during the warm-up process
3Temperature
If the valve duration is extended to increase exhaust gas temperature, then the catalyst warms up faster, but the emission of hydrocarbons increases
Solution Approach 1:
The patent applies dynamics by making the valve duration adjustable rather than fixed. The ECU dynamically changes the exhaust valve duration based on real-time conditions including exhaust gas temperature, engine load, and catalyst activation state to optimize the balance between warming up the catalyst and controlling hydrocarbon emissions
4Power
If the intake valve duration is increased to improve combustion, then the power output increases, but the emission of nitrogen oxides increases
Solution Approach 1:
The patent applies dynamics by enabling dynamic adjustment of intake valve duration based on operating conditions. The ECU modifies intake valve duration in response to engine load, temperature, and emission control requirements to balance power output with NOx emission control
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
The system reduces the amount of nitrogen oxides and hydrocarbons emitted, ensuring that the three-way catalyst is effectively warmed up and capable of purifying exhaust gases, thereby minimizing emissions exiting the vehicle.
Implementation Method 1
The three-way catalyst TWC is a type of the catalytic converter and reacts with hydrocarbon compounds, carbon monoxide, and nitrogen oxide (NOx)s (NOx), which are harmful components of exhaust gas, to remove these compounds
Implementation Method 2
an electrically heated catalyst disposed downstream of the HC trap and provided with a heating device
Data Source
AI summary
A system of controlling an engine provided with a dual continuously variable valve duration device may include the engine including a combustion chamber, an intake valve, an ignition switch provided in the combustion chamber, and an exhaust valve, the CVVD provided to adjust an intake duration of the intake valve and an exhaust duration of the exhaust valve, a warm-up catalytic converter (WCC) including a three-way catalyst (TWC) for purifying hydrocarbons, carbon monoxide, nitrogen oxides contained in the exhaust gas downstream of the engine, a Hydrocarbon (HC) trap disposed downstream of the warm-up catalytic converter for adsorbing and removing the hydrocarbons contained in the exhaust gas, an electrically heated catalyst disposed downstream of the HC trap and provided with a heating device, a three-way catalyst (TWC) disposed downstream of the electrically heated catalyst for purifying hydrocarbons, carbon monoxide, and nitrogen oxides contained in the exhaust gas, and a controller for adjusting an ignition timing of the ignition switch, the intake duration and the exhaust duration based on a driving condition of the vehicle.