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).
Tests and proposed modifications for a dynamo's charging system and output.
| Identifier | ExFiles\Box 163\6\ img115 | |
| Date | 3rd January 1931 | |
| -2- EFC1/AD3.1.31. contd. The particular test on 58-GN has been extremely useful in shewing up the limitations of the system. It is our opinion that it must definitely be taken that the dynamo output must be reduced when there is very little or no load connected to it except the battery. The output in these circumstances is not only equal to what it is arranged to be to suit the head lamps, but is increased to a considerable extent resulting from the rise of battery P.D. particularly in the final stages of charge. It is now considered demonstrated (see Sg{Arthur F. Sidgreaves - MD}21/E31.12.30) that the half charge scheme comprising 48 coil dynamo, even with the lowest value resistance will not provide sufficient output for winter Town running conditions without resorting to garage charging. Now that the idea of the one-way interconnection is, we now suppose, better not entertained, we have to look round for other means. One suggestion has been retaining the full output in the side and tail position, this appears to be, on all counts, a good proposition because it provides for a definite increase in charging output in the very circumstances when such an increase is required. This modification has now been experimentally instructed and will be fitted to 58-GN. A further experiment which is being instructed is a reversion to the 56 coil armature with slots cut wider and deeper to take one gauge heavier copper conductors. This will make the tooth to slot proportion appear wrong from an ordinary point of view (i.e. that of shunt wound dynamo design). Nevertheless, it is probably not wrong and more definitely right in the case of battery controlled machines for approximately constant output at varying speeds. It will be remembered that an improvement in dynamo output in the direction of greater output and better maintenance of output at speed, has frequently been made by increasing the reluctance of the magnetic circuit by modifying the pole pieces. There appears no reason why the increase of reluctance should not be made by removing iron from the armature core in place of removing iron from the pole pieces, which former removal at once introduces the possibility of increasing the conductor size and therefore the possible output of the machine for a given degree of heating without, at the same time, very materially affecting the cutting in point because the number of conductors remains the same. | ||