Patent GB-689972-A (GB)
Abstract: 689,972. Two-stroke engines; cycles; sleeve valves. SERSTE, J. E., TEPLOW, [nee Serste], J., SERSTE, P., and SERSTE, P. Oct. 21. 1949 [Oct. 25, 1948], No. 27104/49. Classes 7 (ii) and 7 (vi). In a two-stroke engine comprising a cylinder 10 having a ring of ports 11 near its upper end and a ring of ports 12 near its lower end, the two rings of ports constituting exhaust and inlet ports, respectively, or vice versa, the ports 11 having a single sleeve valve or a pair of oppositely moving concentric sleeve valves 13, 21 associated therewith, whilst gas flow through the lower ring of ports 12 is controlled by the piston 9 alone or in consingle valve or, in the case where the two sleeve junction with a sleeve valve which is either the valves 13, 21 are associated with the upper ring of ports 11, is that slide valve, for example 13, which moves in the opposite direction to the piston, there is provided a valve operating mechanism, such as crank 16, links 17, 18 and 20, rods 24 and 25 and lever 23, which effects a rapid opening and closing of the ports whereby the exhaust ports 11 are fully open before there is any substantial pressure drop in the cylinder thereby obtaining an almost instantaneous exhaust of burnt gases with an expansion of such gases in the exhaust passage 4 so creating a partial evacuation of the cylinder which sucks in a fresh charge with uniform scavenging, the rapid closure of the exhaust ports preventing return flow of the exhaust gases. The inner and outer sleeve valves 13 and 21 are located externally of the cylinder 10, the inner valve 13 being operated from the engine driven crank 16 through the members 17, 18 and 20 whilst the outer valve 21 is reciprocated from valve 13 by means of the members 23-25. Sleeve valve 13 has inlet and exhaust ports 15, 14 co-operating with ports 12 and 11 whilst sleeve valve 21 which has exhaust ports 22 only reciprocates in the opposite direction to the inner valve 13. In a modification, the valves are located within the cylinder, the piston reciprocating in the inner valve, both valves being operated directly from the engine driven crank through separate linkages and without the use of the overhead rods and lever. In a further modification, the valve operating linkage and engine driven crank are located in an overhead position. The outer sleeve valve may be omitted the inner valve then controlling the upper ports alone whilst the lower ones are additionally controlled by the engine piston. Two engine driven cranks may operate the valve mechanism; moreover, if the engine is of the radial type, a single centrally disposed eccentric is provided. The valve operating linkage, of which there are several embodiments, can be replaced in part by a direct-acting cam mechanism and the valves may have a part rotary instead of a purely axial movement. The Specification as open to inspection under Sect. 91, comprises also connections between the control means and slide valves which are effected through the head of each cylinder; the invention is also applicable to double-acting engines. The slide valves may also be formed by interconnected sections or by sections controlled by one multithrow crankshaft or a plurality of crankshafts. This subject matter does not appear in the Specification as accepted.