GB1324848A - Carburetters - Google Patents

Abstract

1324848 Spray carburettors ZENITH CARBURETTER CO Ltd 7 June 1971 [8 June 1970] 27627/70 Heading F1B In a constant depression carburettor, in which a suction-operated air valve controls an induction passage throat and moves a profiled needle to control the effective area of a fuel metering orifice, part of the total fuel passing through the fuel metering orifice is passed through a transfer passage into the induction passage downstream of a throttle valve when the latter is closed or substantially closed the transfer passage being connected to the induction passage at the throat and at a position downstream of the throttle valve and is shut off from the mixing chamber. Fuel from a float chamber passes through orifice 22, Fig.2 and is mixed with air passing through duct 29 the resultant mixture passing through bore 23 to throat 16. When throttle 17 is substantially closed the suction acting on port 28 causes some of the mixture to be diverted via cavity 25 and duct 27 to port 28. Further air is added to the mixture via ducts 31, 34, 36, 37, 38 and 33, the rate of air flow being determined by screw plugs 39, 44. In another embodiment the arrangement for adding extra air to duct 27 is omitted and a control valve may be included in the passage to port 28. Air passing through duct 29 to cavity 22 forms an emulsion with the fuel or the provision for such air supply may be omitted.