Hybrid Vehicle Catalyst Light-Off Control
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Solution Overview
Problem
Current catalyst light-off processes in hybrid electric vehicles are ineffective when the high voltage battery is in a charge limited state, as they rely on additional charge that the battery cannot accept, leading to inefficient catalyst heating and emission conversion.
Innovation Solution
A method and apparatus that determine if the high voltage battery can accept the charge required for the standard light-off process, and if not, alter engine operation to deliver an acceptable amount of charge by modifying engine speed, torque, and spark timing to efficiently warm up the catalyst, ensuring it reaches the light-off temperature even in charge depleting mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the standard light-off process is used to heat the catalyst, then the catalyst reaches light-off temperature quickly, but the high voltage battery cannot accept the charge generated during this process
Solution Approach 1:
The system dynamically adjusts engine operating parameters (speed, torque, spark timing) based on real-time battery state of charge and charge acceptance capability. When the battery cannot accept charge, the controller modifies the light-off procedure to limit charge generation while maintaining catalyst heating effectiveness, creating a dynamic adaptation to changing system conditions.
Solution Approach 2:
The invention changes engine operating parameters including increasing engine speed, reducing torque demand, and adjusting spark timing to control the balance between charge generation and catalyst heating. By modifying these parameters, the system can limit the amount of charge generated during light-off to match battery acceptance capability while still achieving adequate catalyst temperature rise.
2Temperature
If the engine operates at constant speed and torque during light-off, then the catalyst heats efficiently, but the battery becomes overcharged when charge limited
Solution Approach 1:
The control system continuously monitors battery state of charge and charge acceptance levels, using this feedback to determine whether to implement the standard light-off procedure or a modified version. The feedback loop allows the system to adapt engine operating parameters in real-time based on battery conditions, preventing overcharge while maintaining catalyst heating effectiveness.
Solution Approach 2:
When the battery is charge limited, the system applies partial light-off action by limiting the engine parameters that would normally generate excessive charge. Instead of fully engaging the aggressive light-off mode, the controller applies a moderated version that generates only the acceptable amount of charge needed to reach light-off temperature without overcharging the battery.
3Loss of time
If spark timing is retarded to heat the catalyst faster, then light-off temperature is reached quicker, but charge generation increases beyond battery capacity
Solution Approach 1:
The system dynamically adjusts spark timing based on battery charge acceptance levels. When the battery can accept charge, more aggressive spark retardation is applied to heat the catalyst faster. When the battery is charge limited, the spark timing is adjusted to a less aggressive setting that generates acceptable charge levels while still achieving light-off temperature within an extended but acceptable time frame.
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
The solution enables efficient catalyst heating and emission conversion in hybrid electric vehicles, even when the battery is charge limited, meeting strict emission standards by optimizing heat rate profiles and exhaust gas conditions, thus ensuring compliance with SULEV emissions standards.
Implementation Method 1
the temperature of the catalyst rises to its 'light-off' temperature
Implementation Method 2
a catalytic converter, which converts the engines' toxic exhaust emissions into non-toxic substances such as carbon dioxide, nitrogen and water
Implementation Method 3
internal combustion engines combine with electric propulsion systems
Data Source
AI summary
A method and apparatus for heating a catalytic converter's catalyst to an efficient operating temperature in a hybrid electric vehicle when the vehicle is in a charge limited mode such as e.g., the charge depleting mode or when the vehicle's high voltage battery is otherwise charge limited. The method and apparatus determine whether a high voltage battery of the vehicle is incapable of accepting a first amount of charge associated with a first procedure to warm-up the catalyst. If it is determined that the high voltage battery is incapable of accepting the first amount of charge, a second procedure with an acceptable amount of charge is performed to warm-up the catalyst.