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).
Article describing a 'Robot Strangler Control', an automatic device for regulating the fuel mixture when the engine is cold.
Identifier | ExFiles\Box 31\5\ Scan101 | |
Date | 2nd May 1933 | |
X148P Reprinted from The Motor May 2, 1933. ROBOT “STRANGLER” CONTROL A Clever Device which Automatically Regulates the Strength of the Mixture when the Engine is Cold A NEW device which has been evolved by S. Smith and Sons (M.A.), Ltd., in collaboration with Mr. Carl Skinner, of the S.U. Carburetter Co., makes it possible to dispense entirely with the usual hand control for the strangler or starting mixture. Furthermore, it regulates the richness of the gas in a far more accurate and sensitive manner than can any driver, so safeguarding the engine against the doses of pure petrol which it is apt to receive when a strangler is misused. The mechanism, although ingenious, is of a simple and sturdy character, and therefore adds but little complication, while the risk of failure appears to be extremely slight. Developed for the S.U. Carburetter Two points must be emphasized at the outset: First, that this new control has been developed specially for the S.U. carburetter, and, secondly, that it is only suitable for fitting by car manufacturers; it cannot be supplied as an accessory. It will be recalled that in the S.U. carburetter the mixture is enriched for starting purposes by a hand control which moves a jet downwards away from a tapered needle. The new Smith device takes over this duty and automatically regulates the richness of the mixture in accordance with engine temperature and the extent of throttle opening. The controlling element consists of a Smithermet thermostat placed in a casing, which is fitted to the water outlet pipe, or to any other convenient part. A spindle, bell-crank lever and link connect the thermostat to the lever which operates the movable jet on the carburetter, as indicated in the drawing reproduced. An ingenious rolling ring washer is employed to seal the spindle, this being practically frictionless and also permitting slight misalignments of the spindle to occur. The most novel feature of the apparatus is that the interior of the thermostat bellows is connected to the inlet pipe of the engine. Consequently, as soon as a cold engine is turned by the starter motor air is exhausted and the device moves away from the fully rich position to some extent. If the throttle be left nearly shut, so as to maintain the vacuum, the richness of the mixture will slowly decrease as the water temperature goes up, because the thermostat fluid compresses the bellows. As a rule, however, a car is taken on to the road long before the warming-up process is complete. The cool power unit may be idling satisfactorily, but so soon as the throttle is opened the loss of inlet suction upsets carburation and causes the engine to stagger unless the mixture be temporarily enriched. This compensation is automatically provided by the Smith device, because, at a touch of the accelerator, the loss in vacuum permits an immediate expansion of the bellows. A Counterbalancing Effect This response becomes less and less marked as the engine warms up because of the counterbalancing action of the thermostat. Finally, when the full working temperature is reached, variations in inlet-pipe suction do not produce any change in the richness of the mixture, the jet being fully up all the time. Apart from the obvious advantage of replacing the often careless efforts of the driver at strangler control by a fully automatic mechanism of this character, the Smith device has the advantage of eliminating the usual connection between the carburetter and the dashboard, the adjustment of which is often upset by the flexibility of the bodywork. No special claim is made for economy in fuel consumption, although it is clear that the device should produce an improvement in this respect as compared with a misused strangler. The adjustment of the carburetter can be effected as usual, and the mechanism is so arranged that there is no load on any carburetter part. Image Caption and Labels: (Right) The controlling device, shown in section, coupled to the movable jet of an S.U. carburetter. In the position shown, a rich mixture is provided. WATER SPACE LIQUID SPACE TO INLET PIPE SLIDING JET CONTROL Temple Press Ltd., 5-15, Rosebery Avenue, E.C.1. | ||