Turbocharger Turbine Recirculation for Cold-Start Catalyst Heating
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Solution Overview
Problem
Vehicles emit excessive emissions during cold starts due to the catalyst in the catalytic converter not reaching its operating temperature quickly, leading to inefficient exhaust gas processing.
Innovation Solution
A system that utilizes the rotation of a turbocharger turbine to create a recirculation flow path through a catalyst heater, heating exhaust manifold and walls to transfer heat to the catalyst, thereby accelerating its temperature rise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the catalyst is used to process exhaust gases, then emissions are reduced, but the catalyst needs to reach operating temperature first which takes time during cold start
Solution Approach 1:
The system performs preliminary heating of the catalyst and exhaust manifold before the engine is started. The heating element is activated in advance to raise the temperature of the catalyst and surrounding exhaust system components, so that when the engine starts and exhaust flow begins, the catalyst is already closer to its light-off temperature, reducing the time needed to reach operational temperature and minimizing cold start emissions.
Solution Approach 2:
The heating element is controlled to operate in periodic cycles during cold start conditions. The system activates the heating element for specific time intervals to build up temperature in the catalyst and exhaust manifold, then allows brief cooling periods, repeating this cycle to efficiently raise temperatures without continuous energy input, thereby reducing time to catalyst light-off.
2Loss of time
If a catalyst heater is added to the system, then the catalyst reaches operating temperature faster, but the device complexity increases
Solution Approach 1:
The heating element serves multiple functions within the exhaust system: it heats the catalyst to reach light-off temperature faster, preheats the exhaust manifold to reduce thermal shock, and can potentially serve as a temperature sensor reference. By making the heating element multi-functional, the system reduces overall complexity compared to having separate dedicated components for each heating purpose.
Solution Approach 2:
The heating element is controlled by the existing engine control unit (ECU) that already manages other emission control functions. The ECU uses temperature sensors and existing control algorithms to manage the heating element operation, integrating it into the self-service control system without requiring a separate dedicated control unit, thereby minimizing additional system complexity.
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
Reduces cold start emissions by effectively warming up the catalyst to its operating temperature faster, minimizing emissions before normal engine operation.
Implementation Method 1
the rotation of the turbine causes recirculated air to flow in a recirculation flow path... the recirculated air is heated by the catalyst heater; and heat is transferred from the heated recirculated air to the exhaust manifold, the exhaust walls
Implementation Method 2
heat is transferred from the heated recirculated air to the exhaust manifold, the exhaust walls between the exhaust manifold and the turbine, the turbine housing of the turbine, the exhaust walls between the turbine and the wastegate, the exhaust walls between the wastegate and the exhaust manifold, and the exhaust walls between the turbine and the catalyst heater
Data Source
AI summary
Control signals are issued to open a wastegate, rotate a turbine, and turn on a catalyst heater disposed between the turbine and a catalyst in response to a trigger signal. The rotation of the turbine causes recirculated air flow in a recirculation flow path including an exhaust manifold, exhaust walls between the exhaust manifold and the turbine, a turbine housing, exhaust walls between the turbine and the wastegate, exhaust walls between the wastegate and the exhaust manifold, and exhaust walls between the turbine and the catalyst heater. Heat is transferred from the recirculated air heated by the catalyst heater to the exhaust manifold, the exhaust walls between the exhaust manifold and the turbine, the turbine housing, the exhaust walls between the turbine and the wastegate, the exhaust walls between the wastegate and the exhaust manifold, and the exhaust walls between the turbine and the catalyst heater.