Multi-mode Powertrain Catalyst Light-off Control
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Solution Overview
Problem
Existing multi-mode powertrain systems face challenges in efficiently managing catalyst light-off in exhaust aftertreatment systems, particularly in achieving rapid and cost-effective activation of catalytic devices while balancing engine operation and battery state-of-charge.
Innovation Solution
A method is implemented to monitor output torque requests and determine preferred engine operating points that minimize engine operating costs, combining engine torque with electric machine torque to satisfy torque demands, ensuring catalyst light-off while managing battery state-of-charge within predetermined limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the engine operates at high torque to achieve rapid catalyst light-off, then the catalyst activation speed is improved, but the fuel consumption and engine operating cost increase
Solution Approach 1:
The patent combines engine torque and electric machine torque to satisfy the output torque request. During catalyst light-off, the system operates the engine at a preferred operating point that minimizes fuel consumption while using electric machine assistance to provide additional torque, thereby achieving rapid catalyst activation without excessive fuel penalty.
Solution Approach 2:
The system dynamically adjusts engine operating parameters (torque, speed) based on catalyst temperature and battery state-of-charge. The control strategy modifies engine torque requests and electric machine torque commands to optimize the balance between catalyst heating rate and fuel consumption, transitioning between different operating modes as conditions change.
2Use of energy by moving object
If the engine operates at preferred operating points to minimize fuel consumption, then fuel efficiency is improved, but the catalyst light-off temperature may not be achieved
Solution Approach 1:
The system proactively manages catalyst temperature by monitoring exhaust temperature and comparing it to light-off thresholds. When catalyst temperature approaches the light-off point, the control strategy adjusts engine and electric machine torque to ensure the temperature threshold is reached, preventing delayed activation while minimizing fuel consumption during the heating process.
Solution Approach 2:
The control system continuously monitors catalyst temperature (or estimates it from exhaust parameters) and adjusts engine/electric machine torque commands based on feedback. This closed-loop control ensures the catalyst reaches light-off temperature while optimizing fuel consumption, transitioning from fuel-efficient operation to light-off-promoting operation when needed.
3Use of energy by moving object
If electric machine torque is increased to assist engine torque, then the engine can operate at more efficient points, but the battery state-of-charge decreases
Solution Approach 1:
The system dynamically adjusts the division of torque between engine and electric machine based on battery state-of-charge, vehicle conditions, and catalyst temperature requirements. When battery SOC is high, the electric machine provides more assistance to enable efficient engine operation. When SOC is low, the system reduces electric machine assistance and adjusts engine operating points accordingly, creating a dynamic balance between fuel efficiency and battery health.
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 effectively initiates catalyst light-off, optimizing engine operation to reduce emissions and fuel consumption while maintaining battery health, thereby enhancing the overall efficiency and cost-effectiveness of the powertrain system.
Implementation Method 1
catalytic devices that are configured to perform one or more of the aforementioned processes on constituents in the exhaust gas feedstream
Implementation Method 2
oxidize, reduce, reform, filter, and otherwise transform exhaust gas constituents
Implementation Method 3
oxidize, reduce, reform, filter, and otherwise transform exhaust gas constituents
Implementation Method 4
operation of the catalyst which is exothermic in nature and is thus self-sustaining
Data Source
AI summary
A multi-mode vehicular powertrain system includes an internal combustion engine fluidly coupled to an exhaust aftertreatment system including a catalytic device and an electric machine electrically coupled to a battery. A method for effecting light-off of the catalytic device includes monitoring an output torque request for the powertrain system and determining a preferred engine operating point having a minimum engine operating cost within a predetermined engine operating region for catalyst light-off. When a state-of-charge of the battery is not approaching a predetermined state-of-charge limit, operation of the engine is controlled to the preferred engine operating point and operation of the electric machine is controlled to a machine operating point wherein the combination of engine torque at the preferred engine operating point and electric machine torque at the machine operating point satisfies the output torque request.