GB718381A - Improvements in or relating to carburettors - Google Patents

Abstract

718,381. Spray carburetters. WILTSHIRE, A. S. Oct. 20, 1952 [Oct. 18, 1951], No. 24302/51. Class 7(3) In a carburetter in which a variable choke aperture is controlled by a piston working in a vacuum chamber, the vacuum chamber being connected by a duct to the inlet passage at a point on the side of the choke aperture nearer to the engine and between the choke aperture and the mixture control throttle and the piston also controlling a needle for varying the area of the fuel jet, a further passage is provided communicating with the vacuum chamber and connecting or adapted to connect it to the inlet passage on the side of the throttle nearer to the engine whereby a pressure drop across the throttle may be utilized to modify the relative pressure in the vacuum chamber and thus, the controlling effect of the piston. As shown, a sliding throttle valve 15 and attached fuel control needle valve 16 are operated by engine suction which acts on the upper surface of the piston 5. The engine suction is transmitted to the space 7 through conduits 9, 11 which lead to opposite sides of a butterfly valve 3. Restrictions 10, 12 may be sharp-edged as shown or Venturi shaped. One of the restrictions may be omitted. Alternatively, the restrictions may be adjustable. Screw-controlled needle or conical valves may be employed. The restrictions may be formed in screwthreaded inserts. This enables the carburetter setting to be altered for different engine requirements by substituting inserts with different restrictions. The restoring force on the piston may be provided by its own weight and/or by a spring. The passage 11 may be connected to the inlet passage at any convenient point between the throttle and the combustion chambers. Specification 510,753 is referred to.