Patent GB-623030-A (GB)
Title: Improvements in or relating to internal combustion engines
IPC: F02B1/00
Filed: 1946-07-08
Abstract: 623,030. Four-stroke engines. NACCACHE, A. July 8, 1946, No. 20309. Convention date, Dec. 12; 1945. [Class 7 (ii)] In an engine operating on the four-stroke cycle in which a cooling medium flows through the power piston or pistons, the gaseous mixture for the explosive charge, after being compressed and cooled, is passed through the power pistons and is again cooled by passing through a heat exchanger before delivery to the combustion chambers of the power cylinders. In one form, Fig. 1, the under side of the piston 1, constitutes part of a volumetric compressor controlled by a rotary valve 11, mixture being drawn into the casing 10 and delivered through a pipe 12 to a first pressure tank 5. The piston includes a cooling chamber 4 having ports 7 which, in the lowest position of the piston, permit flow from the reservoir 5 through the piston to a second pressure tank 6 which has water or air circulating tubes 17 for cooling the mixture which passes through baffles 18, and thence through pipe 13 to the inlet valve 14 of the cylinder 9. In a modification, Figs. 2 and 3, the compressor piston 1<SP>1</SP> and the piston 1 of the four-stroke engine cylinder 9 are arranged in line and their cranks are spaced at 180 degrees. The cylinder 58 acts partly as a two-stroke compressor and partly as a power cylinder for the further expansion of gases admitted through valve 53 and passage 54 after partial expansion in the cylinder 1. The mixture is admitted to the compressor by a valve 51 and delivered on the next stroke through valve 56 to the tank 5, thus completing the compressor cycle. From tank 5, the charge passes through spaces in the pistons 1, 1<SP>1</SP>, as described above, to the tank 6. This tank supplies the inlet valve 14 of the cylinder 9. At the end of the power stroke of the piston, the valve 53 is opened and the partly expanded gases admitted through passage 54 to the cylinder 58 where, after further expansion, the gases are exhausted to atmosphere through valve 55. The cylinder 58 then performs another compressor cycle. For scavenging unburnt gases from the cylinder 9, another valve in the cylinder head may be quickly opened and shut at the ends of the fourth stroke of piston 1 to admit air from a' pressure tank supplied by a compressor driven by the engine and maintained at a higher pressure than the gases in cylinder 9. In a form embodying this feature, Fig. 6, two four-stroke working cylinders are separated by an expander cylinder with its crank at 180 degrees from the power cylinders' cranks. The engine also includes two cylinders 71 working solely as two-stroke compressors. The expander cylinder is supplied alternately by the two cylinders 1 through the passages 54, and completes the expansion started in these cylinders. The righthand compressor cylinder 71 receives mixture from the passage 76, and delivers it through a pipe 78 to tank 5 whence, as before, it passes through the pistons of cylinders 1, 58 to tank 6 which supplies the cylinders 1 alternately through inlet valves 14, the partly expanded gases from the cylinders 1 passing alternately to the twostroke expansion cylinder 58 and being partly exhausted to atmosphere through passage 73. The left-hand compressor cylinder 71 draws 'air through passage 75 and delivers it to a watercooled tank 77 whence it passes through pipes 80 and valves 74 to scavenge the working cylinders. In the case of diesel engines, the scavenging airtank and scavenging valves can be eliminated and both compressors may supply the tank 5. Scavenging can then be effected by advancing the opening of valves 14. In another modification, Fig. 8, each crank-throw is connected to an assembly comprising upper and lower pistons, the upper one working in a four-stroke cycle cylinder 9 while compressors are constituted by the spaces above the piston 103 and below the piston 1. A water-cooled rotary distributor 22 controls flow to the various cylinders. The complete engine is shown in Fig. 9, two assemblies similar to Fig. 8 being separated by a tandem compressor assembly comprising pistons 1<SP>11</SP>, 103. Alternatively, the distributer may be fitted with poppet valves. At the bottom of the stroke, air is drawn through the passage 111 and is then compressed by the pistons 103. The complete engine thus includes six compressor cylinders some of which may be arranged in series with intercooling. In one arrangement, the compressors 103 deliver air to a liquid-cooled tank 107 which may be divided into compartments. A pipe 114 may convey scavenging air from the tank 107 to the valves 74 of the power cylinders. Some of the cooling channels 8 associated with the piston cavities may pass direct to the atmosphere through lines 113. The charge-compressing cylinders are fed from inlet pipes 110 and the distributor valve, and the compressed charge is delivered through pipe 106 to tank 5 which is in communication with tank 6 through certain piston cavities as described above. 'The inlet valves 14 are supplied with charge from the tank 6. In the case of a spark-ignited engine, the lower part of the righthand power cylinder, Fig. 9, and the space beneath piston 1 act as charge compressors. The left-hand power cylinder has its compressor arranged to draw atmospheric air from its pipe 110 and discharge compressed air into the top of tank 107. In this case the pistons 103 do no useful work. For diesel engines, the tank 107 is not required. All three under-piston compressors draw air from the atmosphere and deliver to tank 5, scavenging being performed by advancing the opening of valves 14. In another modification for sparkignited engines, the central and right-hand underpiston compressors are supplied with mixture which is delivered to a central compartment of tank 5 and passes through the central piston 111 to the undivided tank 6. The over-piston lower compressors all draw air from the atmosphere and deliver to the end compartments of tank 5 through tubes 106. Tubes 113 allow this air to pass to atmosphere after cooling the two working pistons 9. Scavenging is effected by air compressed in the left-hand under-piston compressor and conveyed from tank 107 through line 114. In another modification, the tank 6 may be divided by partitions, the inlet pipes 13 being supplied from the central portion. In another modification, the under-piston compressors associated with the power cylinders draw mixture from the pipe 112 and deliver it to end compartments of the tank 107 where the first cooling occurs. The two corresponding under-piston compressors are fed through tubes 109 from the same end compartments and impart a second stage of compression to the mixture and transfer it to end compartments of the tank 5. After cooling the working pistons, this mixture is delivered to end compartments of tank 6 whence it passes to the working cylinders through pipes 13. The under-piston compressor of the expansion cylinder draws air from atmosphere and delivers it to a central compartment of tank 5. The over-piston compressor of the same cylinder draws air through its port 111 and delivers part of the compressed air to the central compartment of tank 5, and thence through the expansion piston to the central compartment of tank 6 which discharges through a valve to atmosphere. The remainder of this compressed air passes to the cen'ral compartment of tank 107 and serves to supply the scavenging valves 74.