Hybrid Vehicle Emission Reduction Strategy
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Solution Overview
Problem
Existing strategies for reducing emissions in vehicles with internal combustion engines after a cold start are inadequate in minimizing hydrocarbon emissions and catalyst light-off time, as they do not effectively manage engine and electric machine torque outputs to optimize catalytic converter temperature.
Innovation Solution
A control system for hybrid vehicles that maintains a steady engine torque output and adjusts electric machine torque to satisfy driver demand when the catalytic converter temperature is below a threshold, and allows adjustments to engine torque when the temperature exceeds the threshold to optimize emissions reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional strategies adjust spark timing, air/fuel ratio, and idle speed to minimize hydrocarbon feed gas, then hydrocarbon emissions are reduced, but catalyst light-off time is not sufficiently minimized
Solution Approach 1:
The invention changes the operating parameters of the engine and electric machine to optimize catalytic converter temperature. Specifically, it adjusts engine torque output and electric machine torque output as controllable parameters to maintain the catalytic converter temperature above the light-off threshold, thereby reducing both hydrocarbon emissions and light-off time simultaneously
Solution Approach 2:
The system dynamically adjusts the torque distribution between the engine and electric machine based on real-time catalytic converter temperature conditions. The controller continuously monitors temperature and modifies torque outputs to maintain optimal operating conditions for emissions reduction
2Object-generated harmful factors
If the controller maintains steady state engine torque output and adjusts electric machine torque output to satisfy driver demand, then emissions are optimized, but the electric machine torque may fall outside its operating range
Solution Approach 1:
The controller implements feedback control by continuously monitoring the catalytic converter temperature and adjusting the torque distribution between engine and electric machine accordingly. When temperature drops below the threshold, the system modifies torque outputs to maintain temperature above the light-off point, creating a closed-loop control system that adapts to changing conditions
Solution Approach 2:
The system takes preliminary action by maintaining steady state engine torque output before emissions become problematic. This proactive approach keeps the catalytic converter temperature above the light-off threshold in advance, preventing hydrocarbon emissions from increasing rather than reacting to emission levels after they rise
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 optimizes emissions reduction by maintaining efficient engine and electric machine torque distribution, ensuring the catalytic converter operates above its light-off temperature, thereby minimizing hydrocarbon emissions and catalyst light-off time.
Implementation Method 1
a catalytic converter configured to operate above a threshold temperature
Data Source
AI summary
A vehicle includes a powertrain and a controller. The powertrain has an engine and an electric machine. The controller is programmed to, for so long as a catalytic converter temperature is less than a threshold, maintain a steady state engine torque output and adjust an electric machine torque output to satisfy driver demand. The controller is further programmed to, responsive to the catalytic converter temperature exceeding the threshold, permit adjustments of the engine torque output to satisfy the driver demand.