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).
The principles and components of a high-tension ignition circuit.
| Identifier | WestWitteringFiles\D\October1919\ Scan30 | |
| Date | 24th October 1919 | |
| Contd. -2- tube, which combination is a condenser; secondly, the high tension rotor which also acts as a condenser of appreciable capacity; thirdly, the spark gaps on the high tension distributor which introduce an element of resistance; fourthly, further high tension wires passing through an earthed metallic tube to the sparking plugs which act as further capacities, and lastly, the resistances of the sparking plug gaps. It will be seen that the coil is placed at a great disadvantage in comparison with a magneto ignition. At the moment of break on the primary circuit, we establish at the high tension terminal of the coil a high frequency oscillatory voltage, at which voltage an oscillatory current of limited amount may be taken from the coil; the resulting impulse has to pass along the H.T. circuit to the sparking plugs and be capable of overcoming such obstacles, in the shape more particularly of resistance and capacity, which come in its path. It will be understood that in order to produce a spark at the sparking plug too much voltage must not be absorbed in overcoming the resistances of the circuit and at the same time a sufficient quantity of oscillatory discharge must be available to enable the capacities met with in its track to be charged and discharged to the corresponding voltage. It is possible on almost any chassis by getting every component of the high tension circuit into its best condition, to produce an ignition which fires perfectly Contd. | ||