Patent GB-770814-A (GB)
Title: Internal combustion engine for operation within the range of medium compression ratios
IPC: F02M69/00
Filed: 1955-06-07
Abstract: 770,814. Charge pumps ; engine charges ; carburetting and vaporizing apparatus ; lubricating. AUGUST, P. June 7, 1955 [June 14, 1954], No. 16292/55. Classes 7 (2) and 7 (3). [Also in Groups XII, XXVI, XXVIII and XXXIV] For use with an engine having a compression ratio in the range 8: 1 to 12 : 1, a mixture formed by carburetting, at a fuel nozzle 43, Fig. 1, or in a low-pressure pump, exhaust gases and/or air (as shown, exhaust gases supplied by a pipe 39) is heated in a device 36 to crack the fuel, which may be kerosene, diesel oil, gas oil or tar oil, and is then supplied to a cylinder-head swirl combustion chamber 8 by a pump 14 via a passage 12 permanently open between its ends and thermally insulated as by a magnesium oxide powder lagging. A needle valve 44, optionally replacing the normal carburetter throttle valve, controls the supply of fuel. In the device 36 exhaust gases passing through an outer chamber 45 heat the mixture as it passes through inner chambers, 51, 52, the internal walls of which are coated with a cracking-promoting catalyst such as iron oxide, and through or over coal or coke 56 in a re-chargeable container 55 and rendered incandescent by the heat so as to form water gas from water vapour added to the exhaust gases via a pipe 47 e.g. from the engine radiator. The pump 14 is operated from 30 degrees to 100 degrees in advance of the working piston 1 by a crank-shaft cam 18 and its clearance is adjustable, e.g. to give pump compression ratios of from 10 : 1 to 15 : 1, by a coned screw plug 16 entering a co-acting coned recess in the pump piston ending in a pump outlet duct 15 co-acting with the passage 12. The opposed surfaces of the pump piston and plug 16 may be coated with a cracking-promoting catalyst such as iron oxide. In the crankcase-compression two-stroke engine shown, air supplied through transfer ports 6 is compressed by the working piston 1 and, with rich mixture passing from the passage 12, forms in the chamber 8 a combustible mixture which is ignited by a sparking plug 7 or, for the higher compression ratios of the above-mentioned range, by a surfaceignition body, an incandescent igniter being provided for starting. Exhaust ports 5 are provided. The underside of the pump piston acts to force oil drawn in through pump cylinder ports (not shown), e.g. from the pump cam casing 24, to the crankcase or to the transfer ducts therefrom, via a slot or groove 21 in the pump-piston rod periodically communicating with a duct 22 leading to the crankcase or transfer ducts. The oil is also forced to the pump piston working surfaces via a non-return valve and suitable bores in the piston. Modified pump pistons are described, a trunk piston, Fig. 4, and a solid piston, Fig. 5, having a tail rod 14a with a transfer cut-out 33 for the pumped mixture, and working in a bore into which opens the outlet 35 of an oil duct branching from the duct 22. Fig. 11 shows duplicated ignition chambers 57, 58 adapted for loop scavenging, the passage 12 being a tube projecting into the chambers. As applied to a four-stroke engine, the pump piston reciprocates once for each working cycle.