Hybrid Exhaust Purification Using Supercharger-EGR Catalyst Heating
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Solution Overview
Problem
Existing methods for purifying exhaust gas in hybrid electric vehicles face challenges such as increased costs, energy inefficiency, and engine size due to the use of electrically-heated catalysts (EHCs), which require separate air supply systems and result in excessive component packaging, making it difficult to shorten the light-off time of the catalyst.
Innovation Solution
A three-way valve is used to connect the supercharger and EGR line, allowing supercharging air to be directed through the EGR line to heat the EHC before engine start, eliminating the need for a separate air supply system and reducing component count, thereby shortening the light-off time of the EHC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If an electrically-heated catalyst (EHC) and separate air supply system are used to shorten light-off time, then catalyst activation speed is improved, but device complexity and material costs increase due to additional components
Solution Approach 1:
The patent merges the air supply function into the existing supercharger system by connecting the supercharger outlet to the EHC inlet through the EGR line. This integration eliminates the need for a separate air supply system, reducing component count and packaging complexity while maintaining the ability to deliver heated air for rapid catalyst activation
Solution Approach 2:
The supercharger is given a dual function: it continues to provide compressed air for engine intake while also serving as the air supply source for heating the EHC. The EGR line, traditionally used for exhaust gas recirculation, is utilized as a passage for directing supercharged air to the catalyst, maximizing the utility of existing components
2Reliability
If electrically-heated catalyst (EHC) technology is used to rapidly activate catalyst, then exhaust gas purification performance is improved, but power consumption increases and battery life decreases
Solution Approach 1:
The system performs preliminary heating of the EHC by delivering supercharged air to the catalyst before engine start or during early operation. This pre-heating action reduces the subsequent need for high-power electrical heating, as the catalyst reaches activation temperature faster using thermal energy from the compressed air rather than relying solely on electrical power from the battery
3Temperature
If fuel after injection is used to increase exhaust gas temperature for catalyst activation, then catalyst temperature is improved, but fuel efficiency decreases and energy loss increases
Solution Approach 1:
The patent replaces the chemical method (fuel after injection) with a mechanical method (electric supercharger) to increase exhaust gas temperature. The supercharger mechanically compresses air, raising its temperature, and directs this hot compressed air to the EHC. This substitution eliminates the need for additional fuel injection solely for heating purposes, thereby improving fuel efficiency while achieving the same temperature increase
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 energy consumption, minimizes material costs, and prevents engine size increase by directly heating the EHC using supercharging air, enhancing exhaust gas purification performance and efficiency.
Implementation Method 1
supercharging air from the supercharger is blown toward the EHC through the EGR line
Implementation Method 2
high-temperature EHC air is delivered to the catalyst
Data Source
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AI summary
An apparatus of purifying exhaust gas of a hybrid vehicle includes an electric supercharger disposed on an air intake line, a post-treatment unit disposed on an exhaust gas line and including an electrically-heated catalyst, an exhaust gas recirculation unit including an exhaust gas recirculation cooler disposed on a recirculation line connecting the post-treatment unit and the intake line and an exhaust gas recirculation valve disposed on the recirculation line, a three-way valve disposed at a position at which the recirculation line diverges into a front end portion and a rear end portion of the intake line, and a controller electrically connected to the three-way valve and configured for controlling the three-way valve connecting the intake line and the recirculation line at the front end portion of the electric supercharger to be selectively opened or closed.