Starting Aid by an Automatic Decompression Valve in a Two Stroke Cycle Diesel Engine

Abstract

In the previous papers the temperature rise due to throttling was applied to a starting aid in a four stroke cycle diesel engine and a crankcase scavenged two stroke cycle diesel engine. In the present paper the same phenomenon was applied to a two stroke cycle diesel engine with a scavenging blower. By releasing the cylinder pressure in the compression stroke with an automatic valve, pressure drop under the ambient can be obtained at the end of expansion stroke. When the exhaust ports open the air rushes into the cylinder, accompanying a considerable temperature rise. After scavenging the charge temperature is lowered, but higher than the scavenge air temperature at the beginning of compression. The calculated temperature rise reached 80°C before scavenging, however, when the delivery ratio was unity, it was reduced to 24°C at the beginning of compression, while the measured was l9°C. In the starting test the minimum cooling water temperature at which the engine could start could be lowered by 30°C in tbe range of small delivery ratio.