GB500290A - Improvements in or relating to carburetters for internal combustion engines - Google Patents

Abstract

500,290. Spray carburetters. HERSEY, J. C. June 24,1938, No. 19667/37. [Class 7 (iii)] In a carburetter in which incoming air is whirled about a main nozzle disposed longitadinally of the air passage, the nozzle has an annular orifice which directs the fuel radially outwards as well as forwardly and the fuel is supplied to the nozzle through a channel of annular section formed with a constriction of smaller cross-section than that of the outlet orifice of the nozzle. The carburetter comprises a frusto-conical body member 7, Fig. 3, having at one end a cylindrical cowl 33 provided with air inlets 36 and at the other end a further frusto - conical member 10 adapted to be secured to the induction pipe. Tongues 34, extending inwardly from the inlets 36, and adjacent gusset plates 35 give the air a whirling motion around a casing 39 carrying the fuel nozzle, the casing being supported by a fuel inlet tube 22. The fuel passes from the tube 22 to annular grooves 42, 43 within the casing 39 and the forward groove 43 communicates with an aperture 47 in a fixed tubular member 44 which separates an adjustable nozzle member J<1> from the casing 39. At its forward end, adjacent the end of the casing 39, the bore of the fixed member 44 is enlarged. forming a shoulder 65B and its mouth is flared outwardly at 50 to form one side of an annnular nozzle, the other side of which is constituted by the movable member J<1>. The member J<1> is shaped as shown in Fig. 5B, the hollowed portion 65 permitting fuel to flow from the aperture 47 past the shoulder 65B when an enlarged portion 65A of the member J<1> is displaced from the shoulder The front portion of the member J<1> conforms to the taper of the casing 39 and mouthpiece 50 of the fixed member 44 to direct fuel drawn out of the nozzle by the whirling air stream, the velocity of which is increased by a Venturi V opposite the nozzle, through triangular apertures 16, 21 in a pair of nested cores 12, 20, the inner one of which is rotatable to act as a throttle valve. The edges of the apertures are chamfered to give a Venturi effect to them. The nozzle member J<1> projects through the ends of the cones 12, 20 and its rear end is threaded at 62 to receive a knurled nut 59 which also screws into a fixed steeve 55 to adjust the member J<1> by a differential screwaction. The member J<1> is hollow to provide for slow running and starting, the fuel for which enters its bore through the rear groove 42 in the casing 39 and either of two apertures 77, 78 in the member J<1> according to whether a tubular member 72, Fig. 5A, inserted in the member J<1> is turned to set an aperture 76 in the tube 72 vertically for slow running or horizontally for starting, its level in the latter instance being below the normal fuel level. The cowling 33 may be replaced by a flared inlet member having its end open for the inlet of air.