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).
Page 2 of the Mallory Ignition Course, Lesson No. 27, explaining the principle of operation for a special oil-burning ignition system.
| Identifier | ExFiles\Box 163\7\ img294 | |
| Date | 24th April 1936 guessed | |
| Page 2 Mallory Ignition Course Lesson No. 27 more easily and give better combustion, it has been difficult to obtain the same troubleproof performance with low-grade fuel as with gasoline, and perhaps for this reason the use of such engines has been limited to a field where flexibility is not so important. It is the writer's opinion that if, in the development of the low-grade fuel oil burning engine, more time had been spent in the development of an ignition system that would readily ignite and give better combustion of low-grade fuels, more headway would have been made on this problem. Low-grade fuel is like green wood, which is difficult to light with a little pine kindling fuel is required. Therefore, in burning low-grade fuel or fuel oil why not use a little more fire? Better results will be obtained from engines using low-grade fuel by increasing the heat of the ignition spark to ignite the fuel instead of by using hot manifolds and hot spark plugs to assist a weak spark to ignite the fuel. The best battery ignition system used on automobiles today will not satisfactorily run an engine using fuel oil with cold injection. This might be considered quite a broad statement, but it has been proven that by installing an automobile ignition system on an oil engine, spark plugs would foul and the engine would smoke badly and lose power. The correctness of the theory that very hot sparks are necessary for burning low-grade fuels in a satisfactory manner has been proven by installing a special oil-burning ignition system, which gave perfect performance on engines that would not operate satisfactorily with the best battery ignition systems or the best magnetos obtainable. PRINCIPLE OF OPERATION OF NEW MALLORY SPECIAL OIL-BURNING IGNITION SYSTEM The Mallory Special Ignition System is based on an entirely new and different principle from any other battery ignition system. The coil is a completely closed magnetic circuit transformer, similar to that used for oil-burning furnaces in homes, and produces sparks of the same character. The operation of the system is as follows: Refer to Fig. 1. Contacts 3 close to permit battery current to flow through primary winding 1 and through resistance unit 6. Magnetic lines are built up in the transformer core in the direction as indicated in Fig. 2. Later, contacts 4 close, permitting current to flow through winding 2. It will be seen that windings 1 and 2 are wound so as to set up opposing magnetic flux. When both circuit breakers are closed, the magnetic lines under the core of the primary 1 and the magnetic lines under the core of the winding 2 oppose each other, as indicated in Fig. 3. Contacts 3 are now opened, but contacts 4 remain closed. The magnetic lines set up by winding 2 cease to travel through the air, as indicated in Fig. 3, and take the course indicated in Fig. 4, cancelling or reversing the magnetic lines that were set up by the primary winding 1. This reversal causes a very rapid change of flux within the secondary coil 9. This change of magnetic flux is from a positive maximum to a negative maximum, giving a spark not only of intense heat, but of twice the duration of the spark from an ordinary spark coil. The dwell of the contacts; that is, the time of closure of the two coils 1 and 2, is indicated in black at 7 and 8. The primary winding closure is indicated at 8. Contacts 3 close. Then 15° later, contacts 4 close, as indicated at 7. Both contacts connect both of the windings into the circuit and keep them closed for 20°, as indicated. Then, 15° later, contacts 4 open. It can be seen that contacts 3 build up the core of the coil in one direction, and contacts 4 reverse the polarity of the coil when contacts 3 open. It is the writer's opinion that the development of this new type of battery ignition is a big step toward the perfection of operation of oil-burning engines or the use of colder carburetion. FIG-2 FIG-3 FIG-4 | ||