Exhaust Pressure Modulation Valve Cold-Start Control
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Solution Overview
Problem
Internal combustion engines experience higher emissions of hydrocarbons, nitrogen oxides, and carbon monoxide during cold-starts due to incomplete fuel vaporization and less efficient catalytic converters, which also slow cabin warm-up.
Innovation Solution
A method involving an exhaust pressure modulation valve to increase exhaust backpressure, an exhaust gas recirculation valve, and a variable geometry turbocharger to regulate engine warm-up, with the goal of accelerating engine and cabin temperature increases during cold-starts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the engine operates at cold-start conditions, then the engine can be started and operated, but emissions of hydrocarbons, nitrogen oxides, and carbon monoxide increase significantly
Solution Approach 1:
The system changes the exhaust backpressure parameter dynamically based on engine temperature. During cold-start, the EPM valve restricts exhaust flow to increase backpressure, which improves fuel vaporization and combustion efficiency, thereby reducing emissions. As the engine warms up, the valve opens to normalize backpressure levels.
Solution Approach 2:
The exhaust pressure modulation valve dynamically adjusts exhaust backpressure based on real-time engine operating conditions, particularly engine temperature. This dynamic control allows the system to optimize combustion efficiency during cold-start while maintaining normal operation during steady-state conditions.
2Productivity
If the engine operates at cold-start conditions, then the engine can be started and operated, but catalytic converters are less efficient and cannot reach operating temperature quickly
Solution Approach 1:
The system performs preliminary heating action on the catalytic converter by increasing exhaust backpressure during cold-start. This elevated backpressure increases exhaust gas temperature and residence time in the converter, accelerating its warm-up to operating temperature before normal emission control begins.
3Temperature
If the engine proceeds through warm-up period, then the engine temperature increases, but the passenger cabin takes time to warm-up from ambient temperature
Solution Approach 1:
The system maintains continuous heat generation during the warm-up period by controlling exhaust backpressure. This ensures the engine operates at optimal temperature continuously, maximizing heat availability for cabin heating throughout the warm-up process rather than allowing temperature fluctuations.
4Speed
If the EPM valve restricts exhaust flow to increase backpressure, then engine warm-up rate increases, but exhaust emissions to ambient are reduced
Solution Approach 1:
The EPM valve acts as an intermediary device that mediates between exhaust flow and backpressure. By strategically positioning and controlling this valve, the system achieves the desired backpressure levels to improve warm-up rate while managing emissions through controlled exhaust flow restriction.
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 reduces emissions and accelerates engine and cabin warm-up by controlling exhaust backpressure, enhancing engine efficiency and passenger cabin heating.
Implementation Method 1
regulating, in response to the identified cold-start of the engine, an exhaust pressure modulation (EPM) valve arranged in a main exhaust passage of the exhaust system... increase exhaust gas backpressure in the main exhaust passage up to a predetermined pressure value
Implementation Method 2
a system capturing the engine's by-product heat energy via engine coolant, and then circulating the engine coolant through a heat-exchanger to transfer the heat energy to air forced into the vehicle cabin
Implementation Method 3
regulating the LPEGR valve to selectively control flow of the engine exhaust gas through the EGR passage following regulation of the EPM valve
Implementation Method 4
a variable geometry turbocharger (VGT) having adjustable vanes... regulating, via the controller, the LPEGR valve to direct the exhaust gas to the VGT
Data Source
AI summary
A method of controlling a rate of warm-up of an internal combustion engine fluidly connected to an exhaust system is disclosed. The method includes identifying a cold-start of the engine. The method also includes regulating, in response to the identified cold-start of the engine, an exhaust pressure modulation (EPM) valve arranged in a main exhaust passage of the exhaust system. The main exhaust passage channels engine exhaust gas to the ambient. Such regulation of the EPM valve will restrict a flow of the engine exhaust gas to the ambient and increase exhaust gas backpressure in the exhaust system up to a predetermined pressure value. Furthermore, the subject regulation of the EPM valve will increase a load on and the rate of warm-up of the engine. A vehicle having an engine and a controller programmed to control a rate of the engine's warm-up of according to the method is also disclosed.