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).
Description of a self-regulating C.F. sparking-plug, detailing its operation based on thermal expansion and its advantages.
| Identifier | ExFiles\Box 58\2\ Scan099 | |
| Date | 28th May 1934 guessed | |
| 2 of the C.F. sparking-plug in a most simple manner: The central electrode is hollow and provided inside with a small rod or pin of very high heat conductivity and high coefficient of dilatation. This pin is firmly located on the end of the electrode inside the cylinder, and the other end of the pin is normally separated from the end of the electrode to which the ignition wire is connected. This pin not being in contact with any metal part and surrounded, at least at its extremity, by stagnant air, while its surface, moreover, is rendered bright by chrome-plating, it only transmits little heat through radiation, but as soon as its temperature has sufficiently increased to cause such dilatation that its originally free end comes into contact with the other end of the electrode, it becomes a powerful heat conductor, transmitting that heat to the outside and thus cooling the end of the electrode itself. This conductivity can vary in proportion with the pressure exerted by the pin on the bottom of the electrode, which pressure is always regulated by the temperature of the sparking plug. We have therefore a self-regulating system, a system working accurately and infallibly, because it is exclusively based on the law of dilatation of bodies. With the C.F. sparking-plug, the following advantages are obtained: 1) It can be used on all types of engines. 2) It works accurately at all speeds. 3) It has a long life, because the head of the electrode never reaches a high temperature. 4) The complete unification (standardisation) of this apparatus, permits a considerable saving in stocks. 5) It can be screened without any difficulty. --------oooooooooo-------- | ||