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 the Standard-Sunbury Engine Indicator and its operating principles, including extracts from 'The Engineer'.
| Identifier | ExFiles\Box 138\2\ scan0201 | |
| Date | 4th November 1940 | |
| 1163 To Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation} from Rm{William Robotham - Chief Engineer}/RC.{R. Childs} THE STANDARD-SUNBURY ENGINE INDICATOR ----------------------------------- The outstanding feature of the Sunbury Cathode Ray indicator is that the electrical output for actuating the cathode ray tube is obtained electro-magnetically, by means of a search coil and a moving diaphragm. Thus, change of pressures, velocities, etc., are converted into an electrical form and applied to the deflector plates of the cathode ray tube. The diagrams obtained are, in consequence, the first differential of the usual indicator diagrams. Should the more usual diagram, i.e. pressure-time, etc., be required, a further unit is provided for electrically integrating the velocity diagram. The following is an extract from "The Engineer", giving a brief description of the indicator. A more detailed description may be obtained by perusal of the articles in "The Engineer" of 13th, 20th and 27th December, 1935, which may be obtained from the R.R. Library: "The Standard-Sunbury Engine Indicator was developed in the "Sunbury Laboratory of the Anglo-Iranian Oil Company Ltd., and manufactured "by Standard Telephones and Cables Ltd., Connaught House, Aldwych, London. "It has its origin in the need for an instrument which could be "used, even at the highest engine speeds, for showing the time taken between "the beginning of injection and the beginning of ignition of fuel in Diesel "engines. "The indicator unit consists of a magnetic member moved by the "pressure or other change which it is desired to examine, and a magnet (permanent or energised depending on circumstances) around the pole of which is "wound a search coil. The system is, in effect, the reverse of a telephone "earpiece; thus movements of a diaphragm caused by changes of air or gas "pressure generate potential changes in the winding of the search coil round "the magnet. "The potential at any instant being proportional to the velocity of the diaphragm, the electrical output from the various indicating "units are proportional to the rate of change of pressure, velocity or valve "lift, etc. "The velocity diagrams obtained (the first differential of the "more orthodox indicator diagrams) are found to be extremely useful for accurately measuring the times at which the changes take place. If it is "desired to inspect the usual type of diagram, this is obtained by an electrical integration from the velocity diagram. | ||