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 design and advantages of a suction-controlled carburettor.
| Identifier | ExFiles\Box 66a\1\ scan0220 | |
| Date | 28th January 1929 guessed | |
| contd :- -9- chance of fuel deposition - could be employed. A butterfly valve operated by the piston would provide the means for obtaining the pressure difference across the slow running unit and would replace the diaphragm shewn in the previous sketch. In practice the inlet to and outlet from the slow running choke could take the form of an annular passage, or rose of holes, round the bore above and below the suction operated throttle. The jets would be of the diffuser or air bleed type and the main diffuser provided with a suitable capacity acceler- ating well. Hand operated mixture control could be obtained by means of a taper needle in the air bleed metering orifice which would allow the submerged metering jets to be of a form possessing the minimum of friction, (thin plate type) and so give the minimum of flow variation with temperature or viscosity alteration. A twin choke carb. on these lines need possess only one suction piston which would control two butterfly throttles on a common spindle. In effect this type of carburetter is a static one having a suction controlled throttle to maintain the necessary pressure difference across the idling unit. The advantages we should expect it to possess are :- (1) Improved snap opening up over the static type of carburetter. (2) Good low speed and idling operation. Automatic over lower range and not dependent on throttle position. (3) Give low induction pipe depression - little in excess of static carb. - hence good acceleration. contd :- | ||