A NEW CARBURETTOR

Evening Star, Issue 22365, 15 June 1936, Page 15

A NEW CARBURETTOR

AUTOMATIC CONTROL A new updraught carburettor has appeared on the British market for which the claim is made of greater power output at a considerable de-

crease in consumption—2o per cent, is the figure given. Novel features include an automati-ca'lly-variable choke and an injectorspraying nozzle. The choke is obtained by cutting grooves in the bore of the tube and dropping a steel ball into each groove. These are free to slide vertically, but are retained radically by three-quarters of their diameter. At rest they remain at the bottom of the choke, thus restricting the bore. As the throttle is opened the rush of air through the choke lifts the balls, thus progressively increasing the choke area. The size*of the choke is thus automatically set by engine load and speed. The spraying nozzle is situated in the mouth of the choke. It .consists of a central tube, through which petrol is drawn, and a tubular shroud which terminates in a cap drilled with three oblique holes. Choke tube depression causes air to rush at high velocity through the holes and to impinge radically upon the petrol issuing from the centre tube. Thus the fuel stream is broken up into a fine mist which, passing to the engine with the main air, forms a homogeneous mixture. A float chamber of normal type governs the supply of petrol which passes to three jets. Of these one is for idling, whilst the other two feed to the spraying nozzle. They might be regarded, in fact, as two main jets feeding in parallel, but the makers prefer to call one a main and the other a balancing jet. Both, incidentally, may be removed without stopping the engine and without loss of petrol. The idling jet, also readily detachable, feeds from a well to a small outlet adjacent to the throttle vane. The outlet is so arranged that a perfectly smooth change-over from the pilot to the main is ensured. A screw-down needle valve regulates the strength of the idling mixture; there is also an air-bleed feeding to the submerged-jet nozzle. 1