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).
Advantages of different ignition coil designs with a nearly closed magnetic circuit.
| Identifier | WestWitteringFiles\R\2December1927-February1928\ Scan065 | |
| Date | 19th December 1927 | |
| To R.{Sir Henry Royce} from EFC. c. BJ. BY.{R.W. Bailey - Chief Engineer} IGNITION COIL WITH NEARLY CLOSED MAGNETIC CIRCUIT. Technical No great advantage is shown on test, neither does there appear to be any reason in principle for an advantage, either from - (1) The reverse order of building a coil, e.g. with the secondary inside and H.T. on the core and primary outside. or (2) The nearly closed iron circuit. So far as we can judge, at any rate in the case of (1), it would appear to be a question largely of manufacturing convenience and cost, and to some extent a question of better heat dissipation. In the case of (2), there would appear to be an advantage on the score of reducing the size and weight of the coil, but in regard to the quantities, we hope shortly to find time to go into the whole question of quantities in the light of our further experience with the working of contact points under various conditions, and particularly that the question of coil quantities (within reason) does not appear to affect the condition of the points as much as might be expected and nothing like so much as the mechanical design of the contact breaker. This being the case the quantity design of the coil may be considered largely from the point of view of current efficiency and economy of running at various speeds rather than necessarily keeping down the amount of current at break. We have had a suggestion of experimental evidence of this by running a coil with a more open circuit core and finding that the points with the new scrubbing action work equally well, the coil taking more | ||