Carburettor providing correct mixture over wide speed range - has secondary jet controlled by inlet depression-acting on diaphragm coupled to needle valve

摘要

The carburettor has a throttle (2) mounted on a spindle (3). The fuel from the float chamber (6) flows through the main orifice and through the venturi (15) to mix with the incoming air. A secondary orifice (9a) is controlled by a needle valve (21) actuated by a spring loaded diaphragm (25). The diaphragm chamber is connected to two orifices (31a, 32a) in the wall of the carburettor near the throttle (2). These orifices jointly control the depression in the diaphragm chamber to give the optimum opening of the needle valve (21) and consequently the optimum fuel to air ratio, over a wide range of engine speed.