A Novel Compressed Air Starting System

This paper describes a patented engine starting system that can replace the conventional 12v starter system in a gasoline engine. A major North American original equipment manufacturer (OEM) is evaluating the system for potential use on its V-8 engine family. The Citotech system injects compressed air into one combustion chamber to move the piston downwards and into another combustion chamber, on the compression stroke, for combustion. Combustion is achieved with control of ignition and fuel injection. This process repeats and cranks the engine until it starts. The system offers a significant weight and cost saving. It has also successfully completed a cold chamber start at -40 deg C. Additionally, the system has achieved warm start times of 0.5s and the system is a candidate starting system for the stop/start or idle/stop economy mode of operation. The Federal City/Highway Fuel Economy Test cycle offers the opportunity to reduce fuel consumption by shutting off the engine during vehicle idle times. The Federal City/Highway test cycle contains 242 seconds of idle time. At idle, fuel consumption ranges between 0.3 gal/hr and 0.7 gal/hr, depending on the size of engine. Generally, large displacement engines benefit more from the implementation of a start/stop strategy than do small displacement engines. For example, the fuel economy of a 4.7 litre engine would improve by 5% to 6%. The major impact occurs during the City portion of the test cycle.