GB1278292A - Carburetters for internal combustion engines - Google Patents

Abstract

1278292 Spray carburetters BRITISH MOTOR CORP Ltd 25 June 1970 [25 June 1969] 31980/69 Heading F1B In a carburetter having a rotary air-choke valve 4, Fig. 1, and a fuel metering valve 11 conjointly controlled in accordance with the depression in passage 1 by a diaphragm 20 via a rack-and-pinion 9, 8 or via a flexible tape (30), Fig. 5 (not shown), the choke valve has an extensive cut-away portion which provides the variable choke passage 13. The cut-away portion is arch-shaped so that at idling it engenders a relatively large movement of the valve 11 for small variations in air-flow. The valve 4 is biased towards its closed position by a flat spiral torsion spring (23), Figs.2, 3 and 4 (not shown), which spring or its anchorage may be responsive to temperature to increase the closing torque of the spring when the incoming air temperature reduces. The valve 4 is supported at each side by ball bearings (5) carried by endplates (6) which can be moved relatively to housing 7 to reduce the working clearance between the housing and valve. Jet tube 15 is adjustable along its axis in accordance with fuel temperature by a bi-metallic strip (28) attached to the lower end thereof, for compensation of viscosity changes in the fuel due to temperature change thereof. The chamber 24 above the diaphragm 20 is communicated with atmosphere through an orifice 22 to produce a damping effect. This may be embraced by arranging on top of the diaphragm a needle valve member co-operating with the orifice. Alternatively, the chamber 24 may be filled with oil and an open-topped oil reservoir is then arranged immediately above the chamber 24 and communicating therewith through a needlecontrolled orifice.