Patent GB-815060-A (GB)
Title: Improvements in and relating to multi-cylinder two-stroke cycle internal combustion engines
Inventor: SMITH JAMES JOHN STEWART
IPC: F02B25/00
Filed: 1954-06-10
Abstract: 815,060. Charging two-stroke engines; cylinders; valves. ARMSTRONG WHITWORTH & CO. ENGINEERS Ltd., Sir W. G. June 6, 1955 [June 10, 1954(3)], Nos. 17054/54, 17055/54 and 17056/54. Classes 7(2) and 7(6) To effect exhaust pressure pulse supercharging in a multi-cylinder two-stroke engine, each cylinder in turn during the early part of its exhaust period has its exhaust so controlled by an engine-driven ported valve g, Fig. 38, as to cut the cylinder exhaust passage f off from the normal exhaust outlet duct and place it in communication with an inlet and/or exhaust passage of a cylinder which has reached the later part of its charging period and has together with its inlet and/ or exhaust passage received charge under pressure. As applied to a four-cylinder engine, the valve g may be a rotary drum having four axial ducts with appropriate porting, but as shown is a rotary sleeve having ports coacting with (a) cylinder exhaust passages f 1  ... f 4 , Fig. 40, (b) an outlet duct or ducts m to an exhaust turbine, a silencer and/or atmosphere, (c) ports in a duct l of a stationary inner drum and (d) passages o 1  ... o 4  leading to cylinder inlet ports b, Fig. 38. Each cylinder is initially charged from a compressor-fed low-pressure air belt i, directly via ports c and, through non-return valves k, via the ports b, excess charge passing both directly into the associated one (marked o on Fig. 38) of the passages o 1  ... o 4  and via the still open cylinder exhaust valve d, into the associated one (f on Fig. 38) of the passages f 1  ... f 4  for return to the cylinder by an exhaust pressure pulse from the preceding cylinder in the firing order when the valve g connects both these passages to the exhaust passage of this preceding cylinder. The valve g revolves at engine speed but may be adapted to revolve at a multiple or sub-multiple thereof, or may be replaced by an oscillating or reciprocating valve. The ports b, c are somewhat tangentially disposed. The ports c may be dispensed with, the ports b extending completely around the cylinder which then has non-return valves k on one side, or on both sides with the passage o passing to the further side of the cylinder on one or both sides thereof. The ports c may extend completely around the cylinder, axially narrow ports b being sited above them and extending partially or completely around the cylinder. The invention is applicable to transversely-scavenged engines, Figs. 33 and 35, and opposed-piston engines, Fig. 36, both the embodiments shown having the rotary drum type of valve g referred to above with axial ducts t 1  ... t 4 . Embodiments are described in which the exhaust pressure pulse is directed only into the inlet passage o of the charged cylinder, or only into the exhaust passage thereof, the passage o being dispensed with. The invention is applicable to threecylinder engines or to engines having banks each of three or four cylinders. Polar timing diagrams and valve time-area diagrams of various embodiments are given. Specifications 571,525 and 572,192 are referred to.