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).
Comparison of pump lag, injection periods, delivery, and spill curves at various injection levels.
| Identifier | ExFiles\Box 179b\3\ img102 | |
| Date | 1st February 1933 | |
| -12- COMPARISON OF PUMP LAG AND INJECTION PERIOD AT MAXIMUM and normal injection. With hole No.3 unplugged (at 120° to supply pipe) the injection period and pump lag were measured at both normal and maximum injection and the results are shown in Fig.9. From 1000 R.P.M. the injection period was 40° but at 800 R.P.M. it fell to 37.5° rising again to 40° at 700 R.P.M. and then falling off steadily to 35° at 330 R.P.M. The peculiar dip in this curve at 800 R.P.M. is apparently quite definite and was observed several times as the accuracy of the observation was questioned. It may be due to a wave effect set up at this particular speed. At 1000 R.P.M. it was observed that after the main injection the valve apparently closed and then momentarily reopened resulting in a small puff of oil being emitted. At the lowest speed the discharge did not issue in a continuous steady spray but showed alternately as a thick and a thin jet. This is caused by the rate of discharge from the nozzle due to the 2250 lbs/sq.in. pressure required to keep the valve from closing being greater than the rate of plunger displacement. As many as eight successive fadings of the jet were noted. The lag at maximum injection is greater than that at normal injection for speeds down to 720 R.P.M. and then is somewhat less. COMPARISON OF DELIVERY AND SPILL CURVES AT NORMAL AND MAXIMUM INJECTION. All the Delivery-Speed curves so far given were taken at maximum injection, the reason for doing this being that with the R.P. combined pump and injector the pump is so arranged that there should be no spill at this control position. Hence it was easy to calculate the theoretical discharge allowing for compressibility of the fuel and the capacity of the unloading valve and by measuring the discharge and spill a good indication could be obtained of how nearly the pump approximated to the ideal performance. | ||