Drivetrain Torque Decoupling for Cold-Start Exhaust Heating
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Solution Overview
Problem
Cold start emissions in internal combustion engines are high due to insufficiently warmed exhaust gas aftertreatment components, leading to non-compliance with emissions standards like EU7, especially under high engine loads.
Innovation Solution
A method for operating a drive train that interrupts the torque-transmitting connection between the internal combustion engine and the drive axle to heat exhaust gas aftertreatment components using the engine's exhaust flow until a release condition is met, allowing for preheating of the aftertreatment system before starting the journey, thereby reducing raw emissions and minimizing tailpipe emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the engine is operated at high load during cold start to meet driver demands, then the drive performance is improved, but the cold-start emissions increase significantly due to insufficiently warmed exhaust aftertreatment components
Solution Approach 1:
The system performs preliminary heating of the exhaust aftertreatment components by interrupting the torque-transmitting connection before the driver needs full drive performance. This allows the catalyst and particulate filter to reach operating temperature in advance, so that when the driver demands high power, the aftertreatment system is already operational and can effectively reduce emissions.
Solution Approach 2:
The torque-transmitting connection is dynamically controlled based on the thermal state of the exhaust aftertreatment system. The system transitions between connected and interrupted states depending on whether the aftertreatment components have reached sufficient temperature, allowing flexible adaptation between emission reduction and drive performance requirements.
2Object-generated harmful factors
If the torque-transmitting connection is interrupted to heat exhaust aftertreatment components, then the cold-start emissions are reduced, but the drive torque transmission is delayed
Solution Approach 1:
The system continuously monitors the temperature of the exhaust aftertreatment components and uses this feedback to determine when to reconnect the torque-transmitting connection. Once the catalyst and particulate filter reach their light-off temperatures, the control system automatically reestablishes the torque connection, minimizing the delay while ensuring emissions are controlled.
Solution Approach 2:
The heating phase is performed in advance during the cold start period when full drive performance is not yet required. By preparing the aftertreatment system beforehand, the system ensures that when the driver needs full power, the emission control is already active, thus reducing the perceived delay.
3Object-generated harmful factors
If additional heating means are added to the exhaust aftertreatment system to reduce cold-start emissions, then the emissions compliance is improved, but the system complexity and costs increase
Solution Approach 1:
The system uses the engine's own exhaust gas flow to heat the aftertreatment components, eliminating the need for external heating devices such as electric heaters or burners. The exhaust gas naturally contains sufficient thermal energy to bring the catalyst and particulate filter to operating temperature, making the system self-sufficient and avoiding additional complexity.
Solution Approach 2:
The solution extracts and utilizes the thermal energy already present in the exhaust gas flow, removing the need for separate heating systems. By taking advantage of the existing thermal resource in the exhaust stream, the system achieves effective heating without adding complex external heating means.
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
Significantly reduces cold start emissions by ensuring the exhaust gas aftertreatment system is operational at the start of the journey, allowing for compliance with emissions standards without the need for additional heating means, thus minimizing costs and emissions.
Implementation Method 1
heating at least one exhaust gas aftertreatment component of the exhaust gas aftertreatment system by an exhaust gas flow of the internal combustion engine
Data Source
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AI summary
The invention relates to a method for operating a drive train (10) in a motor vehicle (100). The drive train (10) comprises an internal combustion engine (20) with an exhaust aftertreatment system (30) associated with the internal combustion engine (20) and a transmission (50) for transmitting a drive torque generated by the internal combustion engine (20) to at least one drive axle (12, 14) of the motor vehicle (100).The method comprises the following steps: - Starting the internal combustion engine (20), whereby a torque-transmitting connection between the internal combustion engine (20) and the drive axle (12, 14) is interrupted, - Heating at least one exhaust aftertreatment component (32, 34, 36, 38) of the exhaust aftertreatment system (30) by an exhaust gas flow (70) from the internal combustion engine (20) while the torque-transmitting connection is interrupted until at least one release condition is reached, - Closing the torque-transmitting connection between the internal combustion engine (20) and the drive axle (12, 14) when the release condition is reached, so that a drive torque from the internal combustion engine (20) is transmitted to the drive axle (12, 14). The invention further relates to a control unit (60) and a motor vehicle (100) for carrying out such a method.