GB520555A - Improvements in or relating to rotary pumps - Google Patents

Abstract

520,555. Relief valves. JOHNSON, J. P. Oct. 25, 1938. Nos. 30880 and 30881. Convention dates, Oct. 25, 1937, and March 18, 1938. [Class 135] [Also in Group XXVI] A rotary pump such as described in Specification 461,509, [Group XXVI], is provided with a by-pass valve 31, attached to a flexible diaphragm 42, which is lifted in the event of the vane pump 27 failing, when an auxiliary pump supplies liquid to the inlet 14. The liquid passes up passages 37, 36, presses against a washer 54, and the underside of the diaphragm, lifts the valve 31 and allows the liquid to pass to the delivery 15. The casing 11 is preferably made of aluminium or similar material, while the rotor 21 and liner 17 are preferably formed of hard steel. Vanes 24 bear on a roller 26. The pump may be used to supply the carburetter of an aircraft-engine, at a constant pressure of approximately 3¢ pounds per square inch. A housing 27 is attached to the casing 11 and is reversed on the latter, if the pump is to rotate in the opposite direction. The valve 31 has an extension 32 which acts as a piston in a 'dashpot. A port 65 contains a plug 66 bored to allow communication between the chamber 47 and the atmosphere. If a supercharger is fitted to the engine, the plug 66 is removed, and a pipe connects the supercharger outlet with the chamber 47. A spring 57 presses on a nut 56, and is adjusted by a screwed plug 58 and a squaresectioned rod 59 which fits in a square hole in the plug. A cross bar 60, secured to the rod, rests in a pair of radial grooves in the top of the part 49. The auxiliary pump which functions when the pump 17 fails, may be of the inclined disc type. In a modification, Fig. 5, the driving shaft 110 has a projection 111 fitting in recesses in the pump rotor. Sealing means comprise a collar 113 on the shaft, and a member 119 which carries disc 120 of flexible material attached to which is a metal disc 121. Pins 122 secure the discs to the member 119. A cover 83 is preferably made of aluminium. A rod 99 for adjusting the plug 98, is provided with a knurled head 101.