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).
Fuel pump delivery calculations, performance testing, and future development plans.
| Identifier | ExFiles\Box 179b\3\ img016 | |
| Date | 6th January 1935 | |
| -5- The calculated delivery, taking into account the effects of the unloading valve and of the compressibility of fuel oil has also been plotted for comparison. From a consideration of engine requirements the ideal delivery curve is a horizontal line as shown chain-dotted in Fig.2. The actual curve given by the R.R. pump was considered to conform sufficiently to this requirement for practical purposes. The spill was also measured and is plotted in Fig.2. It will be noted that the sum of the delivery and spill exceeds the theoretical discharge which suggests that there is considerable leakage from suction chamber to spill chamber under running conditions. The pump was next run at 1000 r.p.m. and the discharge measured for various settings of the control wheel. Fig.3 shows the result of this test. From 5 to 35 notches the curve is a straight line, which indicates that the pump control functions in the required manner. The curve departs from a straight line at the highest injection quantities as the plunger is then being actuated by the peak of the cam and is decelerating, i.e. the straight line portion of the cam has been passed. To date, the pump has run about 9 hrs. and has been free from mechanical troubles. The pump was run for 1 hr. at 335 r.p.m. (the lowest speed of the motor), before making the tests described in the page that this might reduce the chance of the plunger seizing. With the Bosch type plunger (in which there is side thrust caused by the fuel pressure) experience on the rig showed that there was a marked tendency to 'pick up', four plungers having done this, the running time in each case having been about 1 hr. It must be admitted however, that the pump speed was 1400 r.p.m. and that few plungers have seized at 1000 r.p.m. on the engine. The R.R. pump has never been run at more than 1000 r.p.m. Future Development. The fuel spray will be examined by means of the oscilloscope to determine the pump lag and the injection period and will then be tested on the engine. In order to test the effect of the special features mentioned on page 1, it is suggested that the nozzle be removed and a fuel pipe adaptor be substituted and the pump be connected by a fuel pipe line to a Bosch type | ||