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).
Fuel injection timing, pump leakage, and boost control for engine development.
| Identifier | ExFiles\Box 41\4\ Scan012 | |
| Date | 27th January 1930 guessed | |
| - 2 - diagram is no longer anything like the original constant pressure cycle, but is exactly like the common spark-ignition diagram but with a much worse tendency to run up into a sharp peak. Timing - The control of the initial injection point must therefore be altered for variations in speed, power and engine temperature and must be controlled with the utmost accuracy, as a slightly too early pressure-rise causes destructive pressure at dead center. In this connection there is an urgent call for Mr. Stanton's spark-control device to adjust the timing from the indicator diagram direct. Nothing is done yet but the device will presumably be similar to the spark-advance. Leakage - In addition leakage in the small injection pumps must be held to the minimum and to an absolute standard for all cylinders. The only people able to meet the requirements so far appear to be the Ex-Cell-O Tool Co. 1200 Oakman Blvd. Detroit. (Ch. Engr. Mr. C.R. Alden). These people make air-driven internal grinding spindles on special high-speed cup and cone ball bearings of their own design, which run up to 30,000 and as high as 90,000 r.p.m. With these they grind a plunger bore approx. 5/16" dia. x 2" long and then grind & lap (by the Hoke method) a plunger to fit the hole so as to hold ten thousand pounds air pressure below water with a maximum allowed leakage of three bubbles a minute. One can scarcely believe this or believe that such injection pumps are practical when made, but Mr. Stanton insists on the truth of this. Apparently he feels also that the attempt to keep the timing right in all cylinders will be a matter of extraordinary difficulty even if controlled by the indicator diagram. Boost Control - This has not been developed but only rigged up roughly by Pratt and Whitney (using an oil-syringe for the pressure element and a pressure pipe three times as long as it should be without means for draining the system, etc.) The general scheme is shown in attached sketch SK-382. - continued - | ||