Rick Rooney
Emissions Testing Specialist, HORIBA Instruments, Inc.

Title: “Emissions Testing Solutions for Hybrids”

Measuring emissions from Hybrid Electric Vehicles (HEV) of all types poses numerous challenges due to minimal Internal Combustion Engine operation during the emissions test cycles.   Each type of hybrid has a different control strategy for using both the internal combustion engine in conjunction with battery power.  In the case of Plug in Hybrids, there are many times the ICE will not run and the vehicle will operate on battery power alone.  CVS technology and Bag Mini Diluter technology offer challenges to measuring accurate emissions.  Bag Mini-Diluter technology offers advantages in sampling emissions from PHEV’s due to the ability to offer lower bag dilution ratios than the CVS method, but there are still limitations.   To overcome these limitations, the Bag Mini-Diluter has been enhanced to optimize the dilution ratio of the sample in the bag after the test using known dilution air volume. 

One of method of detecting PHEV Internal Combustion Engine operation during the emissions test cycles uses a direct ultrasonic flowmeter.  The direct ultrasonic flowmeter measures the exhaust flowrate of the vehicle and sends a signal to the Bag Mini-Diluter to command bag fill activation.  An enhanced direct ultrasonic flowmeter has been developed by  HORIBA which enables the flowmeter to measure flow from PHEV vehicles and distinguish between low idle flow and ICE  off conditions.

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