Electrically Heated Cold Light-Off Catalyst for Startup Emissions
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Solution Overview
Problem
Existing aftertreatment systems in vehicles are inefficient during engine startup due to the time required for exhaust to heat up to optimal temperatures for pollutant conversion, leading to suboptimal pollutant removal efficiency.
Innovation Solution
A control system incorporating a cold light off catalyst (CLOC) with an electrical heating element positioned upstream of the main catalyst, controlled by a controller to rapidly heat up and reach operating temperature, with a bypass valve to divert exhaust flow, optimizing catalyst efficiency during engine startup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the main catalyst is used for pollutant conversion, then pollutant removal efficiency is improved, but there is a delay in reaching optimal operating temperature during engine startup
Solution Approach 1:
The CLOC is activated before the main catalyst reaches operating temperature during engine startup. The controller commands the CLOC valve to route exhaust flow to the CLOC upstream of the main catalyst, enabling preliminary pollutant treatment while the main catalyst is still heating up. This preliminary action resolves the contradiction by providing immediate pollutant conversion capability without waiting for the main catalyst to reach optimal temperature.
2Speed
If the CLOC is heated using exhaust flow, then the heating process is energy-efficient, but the heating speed is insufficient to quickly reach operating temperature
Solution Approach 1:
An electrical heating element is integrated into the CLOC to provide preliminary heating before exhaust flow is routed through it. The controller activates the electrical heating element when engine exhaust temperature is below a threshold, enabling the CLOC to reach operating temperature faster than exhaust heating alone could achieve. This preliminary electrical heating action resolves the contradiction by providing rapid heating capability while maintaining overall energy efficiency through subsequent exhaust-based heating.
Solution Approach 2:
The system changes the heating parameter from purely thermal (exhaust flow) to a combination of electrical and thermal heating. The controller monitors exhaust temperature and switches between electrical heating mode (when temperature is low) and exhaust heating mode (when temperature is sufficient), dynamically adjusting the heating parameter to optimize both heating speed and energy efficiency.
3Productivity
If the CLOC valve routes exhaust flow to the CLOC, then the CLOC reaches operating temperature faster, but the turbine receives less exhaust flow
Solution Approach 1:
The CLOC valve is dynamically controlled to route exhaust flow between the turbine and the CLOC based on operating conditions. The controller commands the valve to the CLOC position when rapid heating is needed (during cold startup), and to the turbine position when the CLOC is operational or during normal operation. This dynamic routing resolves the contradiction by temporarily sacrificing turbine exhaust flow to achieve rapid CLOC heating when most needed, then restoring normal flow paths when the CLOC is operational.
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
Enhances the efficiency of pollutant conversion by quickly heating the CLOC to operating temperature, ensuring effective pollutant treatment before the main catalyst reaches optimal conditions, thereby improving overall emission control.
Implementation Method 1
The electrical heating element is disposed at the CLOC and configured to selectively heat the CLOC
Implementation Method 2
cold light off catalyst (CLOC)... pollutant conversion begins at high temperatures such as over 350 C depending on catalyst formulation
Data Source
AI summary
A control system for a vehicle having an engine and a main catalyst disposed in an exhaust system includes a cold light off catalyst (CLOC), an electrical heating element, and a controller. The CLOC is positioned in the exhaust system upstream of the main catalyst. The electrical heating element is disposed at the CLOC and configured to selectively heat the CLOC. The controller is configured to: determine an initialization event; activate the electrical heating element based on the initialization event; determine, subsequent to activating the electrical heating element, whether at least one of the CLOC has reached a CLOC operating temperature and the main catalyst has reached a main catalyst operating temperature; and command the electrical heating element to deactivate based on at least one of the CLOC reaching the CLOC operating temperate and the main catalyst reaching the main catalyst operating temperature.