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 proposal for adapting a cross rotary valve system to a 25 HP engine.
| Identifier | ExFiles\Box 158\4\ scan0144 | |
| Date | 28th May 1937 guessed | |
| Cross Rotary Valve Design for Adaptation to 25 H.P. Rolls Engine. --------------------------------------------------------------- The design provides for valves to be disposed co-axially along the top of the cylinder block. Although this valves-in-line arrangement is not equal for maximum power to the design where the valves are at right angles to the crankshaft, yet it is to be preferred where silence and simplicity are of major importance. This design would, however, be very efficient as it incorporates the type of valve used so successfully on single cylinder engines, and the inlet and exhaust passages are smooth and unrestricted. This particularly applies to the inlets which have only gentle bends and downdraughts straight into the cylinders. The inlet design lends itself to the use of a conventional induction pipe or where maximum power is required three separate carburetters may be fitted. The drive for the valves could be taken direct from the crankshaft by duplex chain, the ratio being 2 : 1. The chain tensioning sprocket could be used for driving the fan. The bearing bracket for this member would be slidably mounted to provide adjustment. The four exhaust and the three inlet castings are bolted solidly to the cylinder block. The four exhaust castings carry the reaction tube, which member takes all the explosion load, and is offset to the correct amount for the operation of the controlled valve loading scheme. Further, the reaction tube also acts as top water pipe. Water passes completely around the cylinder head before it can enter the valve cap which communicates with the reaction tube. Similarly water passes up through each exhaust casting and leaves via a hole in the reaction tube bearing. The inlet castings are not cored for water, but this could easily be done if thought desirable for mixture warming. Owing to the uneven spacing of the cylinders the six separate cylinder heads are not all alike, two having a centrally disposed port and the remaining four being slightly offset. Although it is necessary to alter the cylinder block casting this modification would only entail a temporary addition to the existing pattern. The compression ratio should be about 9 : 1, and it is to be expected that the optimum consumption would be below .45 pints per B.H.P. hour. A B.M.E.P. of 140 lbs. per square inch at 4000 r.p.m. should also be easily achieved on 80 octane fuel. The bottle neck shape of combustion chamber has been proved to give very smooth running, and it is expected that this unit would give that type of power which is desired for a high class car. | ||