Exhaust Gas Aftertreatment Heating via Recirculation Circuit
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Solution Overview
Problem
Existing combustion engines face challenges in rapidly and efficiently heating exhaust gas aftertreatment devices, especially during cold starts, particularly in vehicles with combined internal combustion and electric driving, where exhaust gas mass flow is low or non-existent, leading to inefficient heating and increased pollutant emissions.
Innovation Solution
The integration of an electrically assisted exhaust gas turbocharger with a recirculation circuit that uses a heating medium warmed by a heating element to efficiently heat the exhaust gas aftertreatment device, even when the engine is stopped, by circulating the heated medium through a conduit element connected downstream and upstream of the aftertreatment device, minimizing heat loss and allowing for rapid warming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If exhaust gas is used to heat the exhaust gas aftertreatment device, then heating can be achieved, but heating speed is slow and efficiency is low when exhaust gas mass flow is low or non-existent
Solution Approach 1:
The heating element activates before the engine starts or before exhaust gas flow is sufficient, pre-heating the exhaust gas tract and aftertreatment device. This preliminary heating action ensures that when exhaust gas flow becomes available, the system is already warmed up, significantly reducing the overall warm-up time and improving heating efficiency during cold start conditions.
Solution Approach 2:
An electric heating element is introduced as an intermediary heat source to supplement or replace exhaust gas heating when exhaust gas mass flow is insufficient. The heating element converts electrical energy to thermal energy, providing the necessary heat to warm the aftertreatment device and exhaust gas tract, thereby decoupling the heating function from the availability of exhaust gas flow.
2Temperature
If a heating element is used to heat the exhaust gas tract, then heating efficiency improves, but energy consumption increases
Solution Approach 1:
The heating element operates periodically rather than continuously, activating only when exhaust gas temperature is below a threshold or when exhaust gas flow is insufficient. The control unit monitors temperature and flow conditions, switching the heating element on/off accordingly. This periodic operation reduces overall energy consumption while maintaining effective heating when needed.
Solution Approach 2:
A control unit continuously monitors the temperature of the exhaust gas aftertreatment device and exhaust gas mass flow, using this feedback to control the heating element operation. When the aftertreatment device reaches sufficient temperature or exhaust gas flow becomes adequate, the control unit deactivates the heating element, optimizing energy usage based on real-time system conditions.
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 solution enables rapid and efficient heating of the exhaust gas aftertreatment device, reducing pollutant emissions and maintaining a low temperature gradient, thus enhancing the overall heating efficiency and reducing emissions, especially after cold starts.
Implementation Method 1
at least one heating element for heating a gas flowing through the exhaust gas tract is arranged in the exhaust gas tract upstream of the exhaust gas aftertreatment device
Implementation Method 2
air can be conveyed as a heating medium by means of the at least one impeller into the exhaust gas tract. The heating medium can be warmed by means of the heating element in heating operation to heat the exhaust gas aftertreatment device
Implementation Method 3
at least one conduit element which is fluidically connected to the exhaust gas tract at a first connection point arranged downstream of the exhaust gas aftertreatment device and at a second connection point arranged upstream of the heating element. By means of the conduit element, at least some of the heating medium can be returned from the first connection point to the second connection point
Data Source
AI summary
A combustion engine for a motor vehicle includes an output shaft, an intake tract, an exhaust gas tract, an exhaust gas aftertreatment device disposed in the exhaust gas tract, a heating element disposed in the exhaust gas tract upstream of the exhaust gas aftertreatment device, an electrically assisted exhaust gas turbocharger, and a conduit element which is fluidically connected to the exhaust gas tract at a first connection point disposed downstream of the exhaust gas aftertreatment device and at a second connection point disposed upstream of the heating element.