GB507160A - Improvements in or relating to carburettor throttle controls for internal combustionengines - Google Patents

Abstract

507,160. Spray carburetters. TRIGGS, W. W. (California Machinery & Supply Co., Ltd.) Dec. 9, 1937, No. 34160. [Class 7 (iii)] In a carburetter having a choke valve and an idling passage for supplying fuel to an orifice adjacent the throttle valve, suction-operated means are provided for moving the throttle valve towards its closed position, the action of these means being modified in accordance with the movements of the choke valve. As shown in Fig. 1, the closing position of the throttle is limited by a stop-screw 55 carried by an arm 46 loosely mounted on the throttle shaft 15 and connected to a piston 42 which operates in a cylinder 37 and is subjected to the suction on the engine side of the throttle through passages 62, 63, 58. During idling, the suction causes the piston to compress a spring 49 and maintain the throttle slightly open to permit fuel to be drawn from the idling passage 34. If the engine tends to stall the reduced suction in the induction pipe permits the spring 49 to open the throttle slightly. During overrunning the high suction in the induction pipe moves the piston 42 against the resistance of springs 49, 51 and closes the throttle further to cut off the fuel supply through the idling passage. When the choke valve is operated at starting, a cam 66 lowers a piston valve 64 to prevent the transmission of the suction from the passage 58 to the passages 62, 63 or to the passage 62. In the modified construction shown in Figure 4, the piston 42 is opposed by a single coil spring 70 and its travel is limited by a stop 71 at the point at which the idling orifice 34 remains open. When the choke valve is closed the cam 66 depresses a rod 72 to unseat a valve 73 which puts the chamber 39 into communication with the atmosphere; thus the piston is not responsive to pressure changes in the inlet manifold when the choke valve is closed.