This invention relates to the starting of two-stroke cycle Diesel or slow-combustion engines by means of compressed air.
When starting, the temperature in the cylinder at the end of the expansion of the compressed air is very low (about -50 deg C or -122 Deg F) During the compression, therefore, the attainment of the ignition temperature of the fuel mixture is rendered doubtful, particularly if the scavenging is not sufficient, or if the motor is working without scavenging, so that a reliable ignition and starting of the motor is rendered impossible.
To prevent this state of things and to admit of the ignition temperature of the fuel being attained in two-stroke cycle engines started by compressed air, an equalisation of pressure is brought about between the interior and the exterior of the cylinder prior to the end of the expansion stroke, and the piston is subsequently caused during its continued stroke to draw in atmospheric air or indifferent gas.