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).
Technical discussion on ignition system components including coils, condensers, and contact breaker points.
| Identifier | ExFiles\Box 35\6\ scan 180 | |
| Date | 30th June 1926 | |
| Contd. -2- EC2/T30.6.26. (e) We would like you to help us in this direction by supplying us with a representative U.S. contact breaker unit with tungsten points, and with, say, half a dozen point spares of contact breaker lever and screw points. We do not think there is anything to be gained in having U.S. coils or condensers really, though presumably one condenser will come with the contact breaker. I should have stated that when we run a Remy nearly closed magnetic circuit coil on our own contact breaker with platinum points, we do not get any better results than running our own coil, so far as our experiments have gone. Everything seems to point to it being a question of material and this is the direction in which we are working to obtain improved results with tungsten. (2) Coils. As stated, we admit there may be a little in the effect on the platinum points by using nearly closed iron circuit coils, but both on principle and from observation we do not think there is a great deal in this. The main high frequency oscillation in the primary and secondary circuits at the instant of secondary spark are in mutual opposition as regards the iron core, so that for this oscillation the coil is virtually an air core transformer. (3) Condensers. We have been quite aware that the dielectric resitance of our paper dielectrice condensers is not large and particularly so when they get warm, but we have always looked upon this as an advantage for the very same reason that you suggest that the nearly closed iron circuit coils may be an advantage, namely, that this small conductance effect in the condenser has a damping effect on the main high frequency oscillation. In fact, for reasons stated, it is likely to have perhaps a bigger damping effect than eddy currents and hysteresis in the core of the inductance coil. We are of the opinion that a slightly leaky condenser is definitely better for the platinum points for this reason without materially interfering with the initial intensity of the ignition spark. From the figures you give of the insulation resistance, one can scarcely consider that these condensers have broken down, in fact for the last two or three years we know of no case of failure of one of these condensers in service & their damping effect apparently is some measure of self-protection. Contd. | ||