GB735866A - Improvements in or relating to fuel pumps and systems - Google Patents

Abstract

735,866. Centrifugal and screw pumps. ROLLS-ROYCE, Ltd. May 15, 1953 [Feb. 15, 1952], No. 4150/52. Class 110 (1). [Also in Group XXVIII] In a fuel pump, a pipe or conduit is provided, with an inlet at or near a location at which free air or vapour collects, and a stream of fluid is produced in the pipe or conduit to withdraw the air or vapour and entrain it in the fluid stream. Fig. 1 shows a fuel pump submerged in a fuel tank 10 and driven by an electric motor 15. Fuel under pressure is tapped off from the volute 12a and passes through a pipe 20, gland 19 and bores 18a and 18 in the driving shaft 14 to a nozzle 21. The nozzle discharges into a venturi 22 leading to a drain pipe 23 which preferably discharges to the tank 10. The nozzle and venturi form an injector which withdraws air or vapour accumulating in the central space 16 and entrains it in the jet of fuel issuing from the nozzle. In the fuel pump shown in Fig. 3, air or vapour liberated at the periphery of the impeller 35 passes through an annular gap 38a to a manifold 38, from which it is withdrawn by an injector comprising a nozzle 41 and venturi 39 and discharged through a pipe 40. The entraining fluid comprises fuel under pressure supplied to the nozzle 41 from the volute 36. The manifold 38 may have more than one outlet. The impeller 35 may be of the helical or helicocentrifugal types. Fig. 2 shows a modification of Fig. 1, but a similar modification may be applied to Fig. 3. The venturi 22 is replaced by a plain pipe 24 leading to a discharge pipe 25 having a venturi portion 25b. Entraining fuel is fed from the volute 12a through a pipe 27 to a nozzle 26. An additional nozzle 28 may be provided, fed with an inert gas such as nitrogen. The inert gas, mixed with fuel and air, passes through the pipe 25 to the fuel tank and forms a non-explosive atmosphere above the free surface of the fuel. In any of these embodiments, the fuel used for operating the injector may be derived from the exhaust of a hydraulic motor which drives the pump and is fed with motive fluid from a main fuel pump which is connected in series with the pump, as described in Specification 735,874.