GB389125A - - Google Patents

Abstract

389,125. Valves ; cylinder ports. CURTIS, C. G., 2, Rector Street, New York, U.S.A. July 13, 1931, No. 20032. Convention date, July 12, 1930. [Classes 7 (ii) and 7 (vi).] In a two-stroke double-acting engine with piston-controlled inlet and exhaust ports 8, 18, piston valves 20 are arranged in the exhaust pipes to close these ducts before the pistons 5 close the ports 18 ; by this means a high air charge is possible. The valves are driven by cranks revolving at twice crank-shaft speed so that each valve acts for both sides of its associated cylinder. To reduce the size of these valves two are used in each exhaust duct ; there are four ports 18 leading to each valved passage and the valves are inclined to the line of flow of exhaust. The valves are driven through bell cranks 21 to give a rapid closing movement. They leave the exhaust passages quite unobstructed when full open. Pumps.-An exhaust-driven turbo-blower supplies the air ; the blower set is placed with its axis at right-angles to the main axis of the engine. The Specification as open to inspection under Sect. 91 also describes a two-stage blower 11, Fig. 2 (Cancelled), driven by an exhaust turbine provided with a byepass 13. An electric motor 12 may be used at starting or to augment the drive of the blower during normal running. Some of the air from the blower may be used outside the engine for ventilating &c. Ports.-In a double-acting engine in addition to exhaust ports 2, 4, Fig. 1 (Cancelled), pertaining to the two combustion chambers, there is a central port 3 common to the ends ; a piston valve 6 closes the ports 2 or 4, while the main piston 5 is at outer dead centre, scavenging being effected through the exhaust port 3. Scavenging air is admitted through ports 8, Fig. 3 (Cancelled), designed to cause back flow within the cylinder in order to produce turbulence. The flow of air to the ports is unbalanced by a small piston 14 arranged to be projected into one of the side passages leading to the ports. Specifications 294,281 and 321,514, [both in Class 7 (ii), Internal-combustion engines, Arrangement &c. of], are referred to. This subject-matter does not appear in the Specification as accepted.