CRANK CASE SUPERCHARGING.

Ellesmere Guardian, Volume XLV, Issue 3081, 19 April 1927, Page 2

CRANK CASE SUPERCHARGING.

Supercharging is such a popular topic for discussion that it is interesting to study the possibilities of systems other than those connected with the blower typo of supercharger. There is nothing new in the suggestion for employing crankcasc compression to assist in this way, but an interesting design of this nature has been produced in Southampton, in which crankcase compression is employed first of all to assist in scavenging the cylinder, and, second, to produce a supercharging effect. A four-stroke engine of more or less normal design forms the foundation of the idea, but an air valve, cither "atmospheric" or mechanically controlled, is fitted in the crank case, and the case itself is reduced to the smallest convenient, capacity, so that relatively high crank case compression can be obtained. Connecting the crank case to j the cylinder are ducts, formed after i the manner of transfer ports in a twostroke, and the cycle of operation is, therefore, as follows: —

On the piston rising on the compression stroke, air is sucked into the crank case and compressed therein on the explosion stroke. Toward the bottom of this stroke, when the exhaust valve has begun to open, compressed air from the crank case passes through the transfer ports (when uncovered by the piston) and assists in scavenging the cylinder. The crank case is again filled with air on the piston's upward stroke, and this air is again compressed during the normal suction stroke.