Search Results

Technologies of 4WD chassis dynamometers (CHDY hereinafter) have advanced dramatically over the past several years, enabling 4WD vehicles to be tested without modifying their drive-train into 2WD. These advances have opened the use of 4WD-CHDY in all fuel economy and emission evaluation tests. In this paper, factors that influence the accuracy of fuel economy tests on 4WD CHDY are discussed. Fuel economy tests were conducted on 4WD CHDY and we found that most of the vehicle mechanical loss is the tire loss and that stabilizing the tire loss of the test vehicle is essential for the test reproducibility.

The environmental effects of particulate matter (PM) emissions from vehicles are an increasing concern to those concerned with air quality. A variety of technologies have been developed to measure exhaust particulates. The automotive industry generally uses the gravimetric method to quantify particulate emissions. This method uses a combination of a dilution tunnel and filter to collect PM from the diluted sample gas. The collected PM is later weighed on a microbalance. Because this technique is a batch measurement, it is not possible to determine at what point of an emissions test drive cycle the soot, soluble organic fraction (SOF) and total PM are emitted. A more accurate characterization of PM emissions will require real-time PM measurement under transient test conditions.