Patent GB-320848-A (GB)
Title: Improvements in or relating to carburettors for internal combustion engines
IPC: F02M1/00
Filed: 1928-06-19
Abstract: 320,848. Dicker, S. G. S., (Stromberg Motor Devices Co.). June 19, 1928. Spray carburettors. - In a carburettor of the kind provided with a pump supplying fuel for accelerating, the pump comprises a stationary stem having a passage for the discharge of fuel and a pump-chamber or cylinder movably disposed on the stem. The fuel nozzle 14 is fed from the float chamber 6 through a restricted orifice 73, which may be valve controlled, and a conduit 72 opening into a chamber 81 beneath the nozzle. Fuel for accelerating is supplied by a pump 88 comprising a movable cylinder 90 loosely surrounding a piston 101, the piston sliding on a fixed stem 103 provided with a fuel passage 106 which opens into a conduit 87 communicating with the chamber 81. The piston 101 is normally pressed by a spring 107 against the head 104 of the stem 103, thus closing the inlet 105 to the conduit 106. The cylinder 90 is operated from the throttle valve 12 through an arm 98 mounted on the valve spindle 13 and carrying a roller 99 which bears against a lever 96 carrying the cylinder 90. A spring 100 on the pivot 97 of the lever 96 tends to maintain the cylinder 90 in the raised position. As the throttle is opened, the cylinder 90 is depressed, the pressure transmitted through the fuel causing the piston 101 to move downwards and uncover the inlet 105, and fuel is forced through the passage 106, conduit 87 and chamber 81 to the nozzle. If the throttle remains open, the cylinder 90 is held depressed, and the piston 101 is lifted by the spring 87, thus expelling further fuel until it closes the inlet 105. When the throttle is moved towards the closed position, the cylinder 90 is raised by the spring 100, and fuel flows thereinto through the clearance between the cylinder and the piston or through a check valve. The cylinder 90 may be provided at the upper end with a small valvecontrolled port, the valve being opened by a bimetallic strip at a predetermined temperature to reduce the amount of accelerating fuel supplied. To supply additional fuel when the throttle is fully open, an auxiliary passageway 114, 112 is provided between the float chamber and the conduit 87, the passage being normally closed by a spring-loaded valve 110 the stem 116 of which is engaged by the lever 96 when the throttle is fully open. The fuel nozzle 14 may be provided with a central tube forming a continuation of the orifice 84 through which the accelerating and additional fuel is injected. The fuel nozzle 14 is mounted in a bore 39 in a boss 35, the bore being formed with a crescent-shaped groove 47 which communicates through grooves 41, 42, 43 and holes 44, 45, 46 with the nozzle bore. Aerating air is admitted to the nozzle through a passage 52 in the choke tube 10, a recess 50, and a passage 49 opening into the groove 47, and fuel from the groove 47 passes through a conduit 55 to a slowrunning device 54. Fuel is supplied to the float chamber through a filter 23, the inlet being controlled by a valve 20 bearing on the float lever 26. The carburettor may be provided with an additional fuel supply device of the kind described in Specification 287,474.