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).
The operation of ignition timing, supercharge, and carburation control systems in an engine.
| Identifier | ExFiles\Box 41\4\ Scan015 | |
| Date | 9th February 1929 guessed | |
| - 2 - top dead center. The device will then always tend to reproduce these conditions, and when the ignition is switched off the differential pressure will retard the spark. No centrifugal or Manual advance issued. A light spring to ensure that the spark retards when switched off can be used and the timing of the second "sample" adjusted to compensate for it. (Control of supercharge on aircraft engines is arranged similarly) During partial throttle running the ignition will be automatically adjusted to give an indicator diagram of the same form but of less height. Since pressure effects are small but cumulative there is no tendency to "hunt", and considerable force can be exerted by the device. A magneto can be controlled as easily as a battery ignition head. The mechanism, consisting of a short 5/16" pipe from a cylinder, the two small valves and the advance piston and cylinder, occupies about the same space as the ordinary centrifugal advance. Carburation Control Pressure at top dead center plus the manifold vacuum are balanced against a spring for the carburation control. This depends on the fact (as stated by Mr. Stanton) that in any engine a factor of the manifold depression in inches of mercury plus the pressure at top dead center is a constant, at all times when the engine is operating normally at maximum economy. Thus, on the car demonstrated which was equipped with a pressure gauge from top dead center and an intake vacuum gauge, five times the manifold vacuum in inches of mercury plus the T.D.C. pressure was at all times equal to about 120 when the car was warm and running at a constant speed. In starting, the vacuum is zero and carburation is therefore full strong. As the engine idles and warms up the T.D.C. pressure increases and mixture automatically becomes leaner. As the throttle is opened the vacuum decreases and carburetter becomes as rich, as may be required for acceleration, but in a second or so the T.D.C. pressure begins to pull up and adjusts the mixture back again. A danger exists in the fact that the device cannot distinguish between slow burning due to richness or weakness, and if the mixture is allowed to become too rich it will move the control the wrong way. Mr. Stanton explained how he compensated for this, but I did - continued - | ||