GB831751A - Improvements in or relating to internal combustion engines - Google Patents

Abstract

831,751. Two-stroke engine charge pumps; cooling charge. BROWN, BOVERI & CIE A. G. Aug. 16, 1957 [Aug. 16, 1956], No. 25919/57. Class 7(2) At least one (generally most) of a plurality of engine cylinders has a working piston 11, Fig. 3, whose undersurface forms a scavenging and charging air pump delivering via an individual pump space 8 to inlet ports 2a of the cylinder, whilst a scavenging and charging air receiver 7 common to all the cylinders and fed from an exhaust gas turbo-charger via a cooler and possibly in parallel from' a further compressor communicates via a one-way valve 9 with the space 8 and via a controllable valve 10 with the space 8 or, as shown, with further inlet ports 2b. The undersurface of a further working piston 11a controlling exhaust ports may pump additional air to the space 8 via a cooler 14. The valve 10 may be controlled manually or by engine load so as to be closed only at starting and under small load. Where the piston 11a leads the piston 11 the valve 10 may be closed at all loads during reverse running. The invention is applicable to single-piston cylinders having overhead exhaust valves, and to crosshead and divided crankcase engines; where it is applied to a cylinder or cylinders having reverse-loop scavenging to terminal exhaust ports, other cylinders, Fig. 5, have no one-way valves 9 and their spaces 8 become merely ducts fed via coolers 19 from pump spaces drawing from atmosphere.