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).
Design considerations and testing of a supercharged engine, focusing on the blower, gears, and carburettor.
| Identifier | ExFiles\Box 140\1\ scan0096 | |
| Date | 19th December 1934 | |
| -2- Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}6/KW.19.12.34. We have a certain amount of apprehension that with a pipe sloping downwards from the blower to the manifold, wet mixture may cause loading up when pulling at low speeds in cold weather. We hope that if the blower is below the induction pipe and an exhaust heated hot spot is provided at the point where the mixture rises to go into the induction pipe, loading up may be avoided with the minimum loss of volumetric efficiency. We are rigging up a scheme to try this. Another advantage of having the blower low down is that it provides more room for an air silencer above the carburetter, and also room for a maximum boost control if this is found to be necessary. We feel ourselves that if we are to get the maximum benefit from the supercharger at the intermediate speeds, which are speeds which the customer uses, then we shall have to have a maximum boost control in some simple form. We are rigging such a control up to see how it operates. We were told by Messrs. Graham-Paige that the amount of flexibility in the couplings to the blower worm gear drive had a very definite bearing on the silence of this drive. Our results so far seem to confirm this, but some form of metallic spring drive is really required so that it can give the necessary flexibility in a reasonably compact space. We cannot see a rubber drive giving the necessary deflection without having a very short life. The gears we have been running on the Bentley were manufactured by Messrs. David Brown & Co. of Huddersfield and are not so silent as the gears obtained from America, nor do they wear so well. If the dimensions of the drive which it is proposed to use on the design now being prepared could be finally determined, we could see about facilities being provided for cutting this gear over here and getting some on test on the Bentley. We have of course had no experience whatever on our own cars on the road, and therefore do not know whether we shall get snap opening up without an accelerator pump type of carburetter. We do know, however, that the carburetter fitted to the Graham has a very large accelerator pump capacity. When we have completed our induction pipe experiments we shall concentrate on road tests. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||