From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Trojan pistons, Junkers engine maintenance, and 4-stroke compression ignition engine principles.
| Identifier | ExFiles\Box 179\1\ img092 | |
| Date | 14th November 1931 guessed | |
| (2) The Trojan piston is only 2.5" dia. and no doubt its small size helps. Decarbonising of the Junkers would be accomplished by dismantling one crankshaft and removing one set of pistons, but this seems reasonably easy unless it were desired to clean the exhaust piston rings, which means removing the lower crankshaft. The Junkers appears to be on the whole an engine worthy of further acquaintance. 4 STROKE COMPRESSION IGNITION ENGINES. Regarding the 4 stroke C. I. engines seen at Olympia there appears to be a very general tendency to employ an air space with restricted throat into which the air is compressed, this air issuing forth when the pistons descend, impinging on the oil spray and creating a more prolonged combustion. This appears to be on the principle of combustion at constant pressure rather than constant volume, and contrary to what one would expect is said to operate favourably at high speed. No combustion is said to take place in the air chamber and the uncooled portion of this chamber never exceeds the operational temperature of the piston. The general performance however seems to be limited to well under 100 BMEP. at speeds in excess of 2000 RPM., and it remains to be seen whether this limitation can be exceeded with the principle of combustion employed. Some investigation in the use of air chambers in this way might be useful, as some of the comp. ignition development work in U.S.A. is being done on these lines. Ricardo has however expressed the opinion that for high BMEP. at high speed an approximation to combustion at constant volume with early injection of the fuel is necessary. (TO BE CONTINUED.) E.{Mr Elliott - Chief Engineer} | ||