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).
Characteristics of fuel injection and the method for measuring pump lag and injection period.
| Identifier | ExFiles\Box 179b\3\ img093 | |
| Date | 1st February 1933 | |
| -3- (3) The angular interval between the beginning and end of discharge from the nozzle (termed the "injection period") is constant. and at all speeds and control rod positions (4) The atomisation of the jet must be sufficiently fine to burn rapidly and not so fine that it will not have sufficient penetration. Atomisation should also be uniform. (5) The beginning and end of injection must be sharp i.e. there must be no dribble or secondary injection. The first three characteristics are mainly affected by the pump and the last two are mainly influenced by the injector. In this report the first three quantities only are considered. The purpose of development is to make the injection system function in a way approximating as closely as possible to the ideal outlined above. Except where otherwise stated, the following were the conditions of test :- Suction head 12 ft. Atomiser having 8 holes .010" dia, .025" long. 140º included angle. Injection pressure setting 3000 lbs/sq.in. Differential ratio of injector 0.75. Hence closing pressure 2250 lbs/sq.in. Normal injection quantity 0.235 ccs/cycle. Static injection period at normal injection approx. 19º. METHOD OF MEASURING THE PUMP LAG AND INJECTION PERIOD. This was achieved by examining the jet by a modified form of Elverson oscilloscope. The pump was mounted on the test rig as described in the previous report and with the axis of the jet vertical. The jet sprayed into a cylindrical box 16" dia, 8" high. Three neon lamps were fixed in the box, shielded from the jet so that their light illumined the jet. A cover was fitted to the box and a hood attached so that no daylight could enter the box. The oscilloscope gear box and phase changing device was driven from the pump so that the contact could be broken at any desired pump angle and the jet illumined for a short interval of time. The oscilloscope was phased with respect to the pump by setting the latter at the angle corresponding to the closing of the suction port and rotating the contact until a click was heard in the phones connected in the contact circuit. | ||