GB1206275A - Improvements in or relating to carburettors - Google Patents

Abstract

1,206,275. Spray carburetters. WALBRO CORP. Oct.6, 1967 [Oct.12, 1966], No.45771/67. Heading F1B. In a carburetter with a diaphragm controlled fuel inlet valve 280 and adjustable control valves 272 and 274 for the main and idling jets 340 and 357, fuel flows to the jets through a port 332 controlled by the main jet control valve 274 and adjacent the diaphragm 246A, and an air bleed passage 360 communicates with the passage 352, 354, 356 leading to the idling jet at a point A overlying the diaphragm 246A. Fuel is supplied to the inlet valve 280 by a pump formed by a diaphragm portion 376 of a diaphragm-gasket 244 between the main carburetter body 240 and a plate 242 which also forms flap inlet and outlet valves shown as ball valves 307 and 316. A pulse damping chamber 304 is provided upstream of the fuel pump. Pulsations of engine crank-case pressure operate the diaphragm portion 376 and an accelerationpump diaphragm 255, a restriction 384 being provided in the path to the diaphragm 255. The transmission of crank-case pressure to the diaphragm 255 through passages 378, 382, 386, 388 is controlled by a cross-bore 270 in the throttle valve shaft 268 to operate the diaphragm when the throttle valve 266 is opened. The diaphragm 255 supplies fuel to the main jet 340 rather than the idling jet 357 due to the more circuitous passages to the idling jet. The idling jet may be a tube (152), Fig.1 (not shown), adapted to extend into an engine crank-case (149), Fig.7, (not shown) adjacent a flap valve (151) through which the main mixture from the carburetter flows into the crank-case. The pressure of fuel supplied to the diaphragm controlled inlet valve may be controlled by a valve (72), Figs.1 and 8 (not shown), comprising a ball biased by springs (73, 82) and actuated by a diaphragm subject to fuel and atmospheric pressures through a pin (86).