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 injection pump calculations, test rig setup, and initial performance results.
| Identifier | ExFiles\Box 179b\3\ img014 | |
| Date | 6th January 1933 | |
| -3- Effective Plunger Stroke = 7 mms. Bore 10 mms. Displacement of plunger = 0.55 ccs. Capacity of unloading valve = 0.040 ccs. If P = final fuel line pressure estimated from calculation at 6000 lbs/sq.in. at 1000 r.p.m. – C = Compressibility coefficient, and V = Volume of oil under pressure, then reduction in volume of oil under pressure = CVP = 3.44 x 10^-6 x .14212 x 6000 x 16.38 = 0.048 ccs. Hence theoretical discharge at maximum injection setting at 1000 r.p.m. = 0.550 - .040 - .048 = 0.462 ccs/cycle. At 600 r.p.m. the terminal fuel line pressure = 3000 lbs/sq.in. and injection quantity = 0.486 ccs/cycle. Test Arrangements. All the tests described in this report were conducted on a 'Rig'. This consisted of a cast iron bed on one end of which was mounted an A.C. commutator motor having a speed range of 300 to 2000 r.p.m. The pump and injector was mounted, together with its cam and rocker, in an inverted position in a cast iron box bolted to the bed, and the pump camshaft connected to the motor through an Oldham's coupling. The cam and rocker ran in an oil bath and the injector protruded through the cover of the box. The injection quantity was controlled by a hand wheel at the side of the box. The discharge from the nozzle was collected in a "mushroom" shaped metal vessel, which fitted over the injector, and lead either to waste or to a collecting vessel. The spill discharged through a small pipe at the side of the box. The discharge and spill were collected over timed intervals and measured in graduated measuring cylinders. The fuel passed through Bosch and Tecalemit filters (arranged in series) before reaching the pump. The normal suction head was about 12 ft, but in some tests a head of 1 ft. was used. Test Results. All the preliminary tests were run at 1000 r.p.m. Maximum injection setting and injection pressure 3000 lbs/sq.in. As initially assembled the pump gave a discharge of 370 ccs/min. and spill 151 ccs/min. during an hour's run. When investigating the cause for the large quantity of spill, it was found that the quadrant gear casing stops prevented the plunger from being turned into the position in which the relief passage remained sealed at maximum injection. | ||