GB1312159A - Float chamber carburettors for internal combustion engines - Google Patents

Abstract

1312159 Spray carburetters SOC INDUSTRIELLE DE BREVETS ET D'ETUDES 21 Dec 1970 [19 Dec 1969] 60487/70 Heading FIB I. C. engine carburetter has a float chamber from which fuel is fed to a jet in an air inlet pipe by the difference in pressure between the airspace above the fuel and at the jet which is situated downstream of an air-filter and upstream of a driver-operated throttle valve, there being a valve which connects the air-space to either the air inlet pipe downstream of the filter when the throttle is opened beyond a pre-determined position, or to a point outside the inlet pipe when the throttle is not opened as far as the pre-determined position, there also being provided a temperature sensitive device which keeps the air-space connected to the point outside the inlet pipe when the temperature of the device exceeds a pre-set limit even though the throttle is opened beyond the pre-determined position. The air-space above the fuel in float chamber 1 is connected by a channel 6 to a chamber 7 having two valve seats 8 and 9 and a valve 12 which can close on to either of the seats. When the valve is closed on to seat 8, the channel 6 communicates with atmosphere through an orifice 11. When the valve is closed on to seat 9, channel 6 communicates through pipe 10 with the air-inlet pipe 3. The valve is biased towards seat 8 by a spring 20 and towards seat 9 by a stronger spring 19. A rod 13 connects the valve 12 to a lever 16 which is freely rotatable about the spindle 5 which carries the throttle valve 4, the connection being by a collar 18 which allows lost motion between the rod and lever. Fixed on the spindle 5 is a lever 14 carrying a pin 15 which engages the lever 16 as the throttle valve approaches its closed position, and turns the lever 16 in the same direction. The temperature sensitive device comprises a bi-metal strip which is clamped at one end by screws 23 and has a free end 21 which engages beneath a lug 24 on the lever 16. Operation. When the carburetter body is at its normal operating temperature and the throttle is allowed to close, pin 15 on lever 14 rotates the lever 16 so that spring 19 is compressed and valve 12 is closed by spring 20 on to seat 8. The air-space above the fuel is then vented to atmosphere. If the throttle is opened soon afterwards, spring 19 re-asserts its control and closes the valve 12 on to seat 9 so that the air-space is vented to air-pipe 3. Alternatively, when the engine is hot and is either stopped or idling, the temperature in the engine compartment heats the strip 22 so that end 21 moves upwardly and holds the valve 12 against seat 8. The air-space is then subject to atmospheric pressure which is higher than the pressure existing in the inlet pipe 3 so that the engine receives an enriched mixture for a short time.