GB581216A - Improvements in or relating to the charging of multi-cylinder two-stroke cycle internal combustion engines - Google Patents

Abstract

581,216. Two-stroke engines. CROSSLEY BROS., Ltd., and CARTER, H. D. June 14, 1944, No. 11375. [Class 7 (ii)] In a multi-cylinder two-stroke engine the fundamental exhaust pressure pulse from one cylinder is controlled so that it reaches its peak a little before the closing of the exhaust port of a cylinder which has previously exhausted, the charging pressure being thus increased. The control may be effected by varying the control timing, or the length or bore of the exhaust conduits or by combination of these variables. In the Fig. the lines O, C indicate the opening and closing of the exhaust ports of a two-stroke engine cylinder with loop scavenging. The curve E shows the pressure drop in the cylinder and the curve F shows at P the exhaust pressure pulse in a succeeding cylinder connected to the same manifold. It will be seen that the exhaust manifold has been so designed that the pressure pulse has been utilised to increase the pressure in the cylinder at the time of the closing of the exhaust ports. This may be done by splitting the manifold into two or more parts to serve separate banks of cylinders or by lengthening the branches of the manifold which may be arranged by placing it over the engine. When the manifold is split, the cylinder utilised to increase the pressure may be a later cylinder in sequence than that firing immediately after the one in question. The invention is particularly applicable to an engine having loop scavenging as it will in that case stop the flow of air through the cylinder into the exhaust manifold, but it is also applicable to uniflow, poppet valve, opposed piston and sleeve valve engines. Specification 571,525 is referred to.