Dual-Function Catalyst Preheating and EGR Using Electric Turbocharging
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Solution Overview
Problem
Conventional systems in electrified vehicles struggle to achieve low tailpipe emissions immediately after a cold engine start due to low catalyst conversion efficiency, as the catalysts take time to reach the light-off temperature, leading to inefficient conversion of CO, HC, and NOx.
Innovation Solution
A combined catalyst preheating and exhaust gas recirculation (EGR) system that utilizes an electric turbocharger compressor to heat the catalyst to light-off temperature using intake air and then reverses the flow for EGR, sharing hardware for both functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional catalyst system is used in electrified vehicles with intermittent engine operation, then the system structure is simple, but the catalyst conversion efficiency is low during cold starts because the catalyst cannot reach light-off temperature quickly
Solution Approach 1:
The system performs preliminary heating of the catalyst using the electric turbocharger compressor to force air through the catalyst before the engine starts or during cold operation. This preliminary action raises the catalyst temperature closer to light-off temperature, reducing the time needed to achieve effective conversion efficiency when the engine begins operation.
Solution Approach 2:
The electric turbocharger compressor acts as an intermediary device that forces air through the catalyst during cold starts. This intermediary mechanism enables controlled air flow through the catalyst to generate heat without requiring the engine to be running, bridging the gap between cold engine operation and catalyst activation.
2Reliability
If separate catalyst preheating and EGR systems are implemented, then the catalyst heating performance is improved, but the system complexity and hardware requirements increase
Solution Approach 1:
The electric turbocharger compressor is designed to perform multiple functions: it acts as both a catalyst preheating device by forcing air through the catalyst, and as an EGR (exhaust gas recirculation) device by recirculating exhaust gas to the intake manifold. This multi-functionality eliminates the need for separate heating elements, valves, and control systems that would be required in conventional separate systems.
Solution Approach 2:
The system merges the catalyst preheating function and the EGR function into a single integrated system using the electric turbocharger compressor. By combining these two previously separate functions into one device, the system reduces hardware complexity while maintaining or improving catalyst heating performance.
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
Rapidly heats the catalyst to light-off temperature, reducing emissions and improving fuel efficiency by synergistically combining catalyst preheating and EGR operations without additional hardware, thus enhancing emissions control during cold starts.
Implementation Method 1
a heating element, and a preheating/EGR valve configured to selectively allow flow through the recirculation passage
Implementation Method 2
an electric turbocharger assembly including a compressor and a turbine rotatably coupled by a shaft
Implementation Method 3
an electric turbocharger assembly including a compressor and a turbine rotatably coupled by a shaft
Data Source
AI summary
An internal combustion engine system includes an internal combustion engine, an air intake conduit, an exhaust system with a catalytic converter, a combined catalyst preheating/exhaust gas recirculation (EGR) system with a recirculation passage, a heating element, and a preheating/EGR valve configured to selectively allow flow through the recirculation passage, and an electric turbocharger assembly including a compressor and a turbine rotatably coupled by a shaft. A controller is configured to operate in (i) a catalyst preheating mode where the preheating/EGR valve is opened to allow intake air into the recirculation passage, and the electric turbocharger compressor is operated to force intake air through the recirculation passage and the heating element to rapidly heat the catalytic converter, and (ii) an EGR mode where the throttle is opened to allow intake air to flow into the engine, and the preheating/EGR valve is opened to allow exhaust gas into the recirculation passage.