Patent GB-1005366-A (GB)
Title: Improvements in or relating to carburettors
Inventor: O'NEILL CORMAC GARRETT
IPC: F02M17/09
Filed: 1961-01-02
Abstract: 1,005,366. Spray carburetters. SOLEX. Dec. 12, 1961 [Jan. 2, 1961; May 16,1961], Nos. 50/61 and 17787/61. Heading F1B. A suction carburetter comprising a mixing chamber having on its outflow side a throttle valve and on its inflow side a mixture control valve in the form of a pivoted vane which increasingly opens, against the action of restoring means, with increases in air flow rate in the induction pipe and mechanically controls a fuel metering member in a circuit feeding fuel from a float chamber to a fuel nozzle opening into the mixing chamber, is characterized in that the connection between the vane and its restoring means is such that the closing torque exerted on the vane by the restoring means, for most of the angular movement of the vane, decreases as the vane moves towards its maximum open position. In the carburetter shown in Figs. 3 and 4, the throttle 8 is mounted on a spindle 9 and operated by a control lever 10 having an adjustable stop 11. The reduction in pressure in the mixing chamber 50 produced by the air flow opens a flap valve 3, pivoted on a shaft 4, against the action of a spring 6. As the valve 3 opens, it exposes a reduced area to the incoming air so that the opening torque exerted on the valve is reduced. In addition, the increasing angularity of lever 5 reduces the closing torque exerted by the spring 6. The resultant equilibrium position of the valve 3 is such that the pressure in the mixing chamber 50 increases as the throttle 8 is opened. Fuel from a float chamber enters a housing 19A, passes through ports 28 to a chamber 27 and then to a chamber 35 through an orifice 34 controlled by a needle 30 adjusted by the valve 3 through a flexible coupling 41, which may be of phosphor bronze wire. The movements of the valve 3 are dampened by a piston 31 or by a disc mounted at the end of the shaft 4 and immersed in a viscous fluid such as silicone oil. The fuel in the chamber 35 is drawn into the mixing chamber 50 through a quadrant shaped space 75 and conduits 53, 52, 51. The needle 30 may be axially adjusted relative to a jet 32 by screw means on a housing 25. Air, bled from an arcuate opening 70, Fig. 9, at the upstream end of the carburetter, passes through a passage 71 preferably provided with a calibrated orifice 471, passages 72, 73 and a passage in the float chamber body, to the space 75. The flow through a by-pass 60, 61 leading from the opening 70 to the chamber 50 may be adjusted by a screw 62 to take account of any air leakage around the valve 3 when the latter is closed. Air is also bled from the opening 70 through passages 80, 81, 85, 86, Fig. 7, and passages (not shown) which may have a calibrated orifice and are formed in the housing 19A, to a passage 89 (Fig. 4) connected to the chamber 35 by a port 90. A valve 82, spring-biased to the open position, provides enrichment of the fuel mixture according to the throttle position by means of a lever 120, Fig. 17, operated by a wire member 121 attached to the throttle spindle 9, which member 121 engages a peg 120A on the lever 120 to reduce the amount of air supplied to the chamber 50. Instead, the spindle 9 may carry a disc having a radial projection, which engages under the head of the valve 82, spring-biased to the closed position, to open the latter and thereby weaken the mixture. At starting, a valve 161, Fig. 11, is opened and fuel supplied to a chamber 156, through a passage 155 connected with a dip tube in a well in the float chamber, passes through passage 201 and chamber 202 (Fig. 7) into the mixing chamber 50 through a passage 203 which emerges adjacent the valve 3 so that the mixture is progressively weakened on further opening of the valve 3. The valve 161, spring- biased to open, is controlled by a cam 163 mounted on a spindle 164, Figs. 1 and 11, provided with a lever 165 connected via a pin 176, a bell crank 177, and a link 178 to a lever 179 in unidirectional driving connection with the throttle spindle 9 via an abutment pin 180. Operation of the lever 165, as by a cable connected to a pin 175, thereby opens the valve 161 and the throttle 8 for starting. In an alternative embodiment, Fig. 20, fuel from a float chamber 211 is controlled by two needle valves 230, 231, normally of different characteristics. These valves are operated through linkage 223 to 227 by the movement of the valve 3 biased to the closed position by a weight 241 on a lever 242, the variations in the angular position of which provide the variable closing torque. Two rods and weights may be provided or the weights may be mounted on some other part of the linkage system. The position of the weights on the rods, the size of the weights and the angular position of the rods may be adjusted. The fuel passage to the needle valve 230 may contain a valve 245 which is opened at full throttle by a lever 248 on the throttle spindle acting on a rod 247. The air valve 3 has an opening 235 to provide minimum airflow and has a stop 236. The valve 3 may be controlled by a spring 260, Fig. 21, acting through a flexible member 261 which, when the valve 3 opens, wraps on to a cam 263, to provide a wide range of relationships between airflow and the pressure in the chamber 50. In a further alternative, a second spring comes into action over part of the opening movement of the valve 3. Specification 1,005,367 is referred to. 1,005,367. Spray carburetters. SOLEX. Dec. 12, 1961 [May 16, 1961], No. 13700/65. Divided out of 1,005,366. Drawings to Specification. Heading F1B. The subject-matter of this Specification is repeated in Specification 1,005,366 but the claims are concerned with a carburetter with a mixing chamber having a throttle valve on its outflow side and on its inflow side a mixture control valve whis is operated by the flow rate in the induction pipe and mechanically controls a fuel metering member in a circuit supplying a fuel nozzle in the mixing chamber, wherein, during starting of the engine, the throttle valve and a valve controlling the flow of fuel from the float chamber to an inlet to the mixing chamber adjacent the mixture control valve, are simultaneously opened sufficiently for starting.