Hybrid Catalyst Temperature Control via Power Storage Mediator
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Solution Overview
Problem
Hybrid electric vehicles face challenges in controlling carbon monoxide (CO) tailpipe emissions during aggressive driving, as high engine power commands lead to excessive catalyst temperatures, triggering over-temperature protection measures and resulting in rich air-fuel ratios that exceed the catalyst's reforming capacity, causing unacceptable CO emissions.
Innovation Solution
A method and system that determine if demanded power exceeds a threshold, using a power storage unit to supply supplemental power to the wheels, thereby reducing engine power and minimizing incremental increases, which helps maintain catalyst temperature within safe limits and reduce CO emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If engine power is increased to meet driver demand during aggressive driving, then wheel power is improved, but catalyst temperature exceeds safe limits
Solution Approach 1:
The power storage unit acts as an intermediary between the engine and wheels, absorbing excess power demand during aggressive driving. This mediator enables the engine to operate at lower power levels that keep catalyst temperature safe, while still meeting the driver's power demand through the power storage unit's supplemental power delivery.
Solution Approach 2:
The system changes the power distribution parameters by dynamically adjusting how much power comes from the engine versus the power storage unit. During aggressive driving, the parameter shift allows the engine power to be reduced below what would normally be required at the wheels, thereby reducing exhaust temperature and protecting the catalyst.
2Temperature
If air-fuel mixture is enriched to protect catalyst from overheating, then catalyst temperature is controlled, but CO emissions increase beyond acceptable levels
Solution Approach 1:
The power storage unit serves as a mediator that enables the engine to operate with stoichiometric or lean air-fuel ratios instead of rich ratios. By supplying supplemental power during high-demand situations, the power storage unit allows the engine to avoid enrichment modes that would otherwise be necessary to protect the catalyst, thus eliminating the harmful CO emissions.
3Object-generated harmful factors
If engine power is reduced to maintain catalyst temperature, then CO emissions are reduced, but wheel power delivery is insufficient
Solution Approach 1:
The system merges two power sources - the engine and the power storage unit - to deliver wheel power. The engine operates at reduced power levels that protect the catalyst and minimize CO emissions, while the power storage unit supplements the power delivery to ensure the driver's power demand is fully met. This combination resolves the contradiction between reduced engine power and sufficient wheel power.
Solution Approach 2:
The power storage unit acts as an intermediary that compensates for the reduced engine power output. By storing energy during low-demand periods and delivering it during high-demand periods, the power storage unit ensures that wheel power delivery remains sufficient even when the engine operates at lower, catalyst-protective power levels.
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 effectively reduces CO emissions by up to 5 grams per mile and improves noise, vibration, and harshness during aggressive drive cycles by reducing engine power and speed, maintaining catalyst temperature and ensuring battery durability.
Implementation Method 1
supplying a supplemental power from the power storage unit to the at least one wheel
Implementation Method 2
Catalyst temperature may be greater than exhaust temperature due to the exothermic reactions taking place in the catalyst
Data Source
AI summary
If a demanded power exceeds a predetermined threshold, where the threshold is based on a catalyst temperature, power from a power storage unit is supplied to a wheel.