Patent GB-760721-A (GB)
Title: Improvements in carburetters including an auxiliary starting device
IPC: F02M1/04
Filed: 1954-01-06
Abstract: 760,721. Carburetters. SOLEX. Jan. 6. 1954 [Jan. 17, 1953 ; June 12, 1953 ; Sept. 25, 1953], No. 400/54. Class 7 (3). An auxiliary starting device delivers fuel toward the engine under the effect of the suction existing in the induction pipe downstream of the throttle valve the auxiliary device comprising an independently operated distributing valve for controlling this fuel delivery and conveying the fuel towards the downstream side of the throttle and means are provided operative by the distributing valve for slightly displacing the throttle in the opening direction from its maximum closing position when the distributing valve is brought into a position for which it delivers fuel toward the downstream side of the throttle whereby a larger passage is afforded by the throttle between the portion of the induction pipe upstream of the throttle and engine as long as the distributing valve is in a position in which it feeds fuel toward the portion of the induction pipe downstream of the throttle. The auxiliary starting device may deliver a rich mixture consisting of fuel possibly emulsified with air and additional starting air. In Fig. 1 a distributing valve 15 rotatable manually or automatically. by any thermosensitive or other device comprises a control groove 17 by which it connects a conduit 14 leading from an auxiliary starting carburetter to a passage 16 leading to the downstream side of a throttle valve 5. When the valve is in a position in which the starting carburetter is in operation a cam 20 carried thereby opens the throttle valve 5 slightly. In bringing the starting carburetter out of action the decrease of the sections of flow afforded may be sufficiently progressive if the cam 20 is suitably designed and the groove 17 given a suitable shape. A groove or grooves in communication with the atmosphere are provided either in the surface of the valve 15 or of the flat surface upon which it operates. As described there are two radial grooves communicating with an annular one. Fig. 5 shows a modification in which the cam 20 co-operates with a lever 23 which is free to rotate on the throttle valve spindle. It is possible to adjust the minimum opening of the throttle by acting upon an adjustable screw 26 carried by the throttle lever 18, which bears on an abutment 25 of the lever 23. In Figs. 6 and 7 the starting carburetter distributing valve 30 is arranged to control a supply of additional air as well as to open the throttle valve slightly by means of a cam 20. Thus with the valve 30 in the position shown in Fig. 7 the passage 16 supplies fuel from the starting carburetter passage 14 and additional air from a passage 31. In an intermediate position of the valve 30 and the throttle valve 5 the openings 40, 41 of the passages 31 and 16 are about half closed. The opening 39 of the passage 14 is wholly closed and the passage 14 communicates only through a small orifice 42 with the other two passages. The opening of the passages 14, 16 and 31 must be arranged and the grooves in the disc 30 must be so shaped as to achieve correct progressivity of operation. In Fig. 11 preferably means are provided so that the suction exerted on the fuel supplied by the auxiliary carburetter is reduced when the suction in the induction pipe downstream of the throttle exceeds a predetermined mixed valve as shown while the engine is being driven by the starter the suction is insufficient to move a piston 58 and fuel from the well 11 is drawn in through the orifices of tube 13 and through conduits 14, 50, 54. The throttle is held open by the cam 20 to a degree slightly greater than the normal opening for idle running. As soon as the engine is running the increased suction draws down the piston 58 which closes an orifice 56 and opens a passage 52. Thus fuel can pass only through a calibrated hole 57. Also air penetrates through the passage 52 and the suction which is exerted on the fuel in the tube 13 is considerably lowered. A considerable reduction in the richness of the mixture is obtained which makes it possible to make use of extremely rich mixtures when the engine is being driven by the starter. When the valve 43 is slightly rotated in a clockwise direction the passage 14 is in communication with the corresponding radial groove in the disc only through the small area recess 49 and only small sections of the passages 50 and 52 are connected together. The throttle valve returns to a position closer to the idle running position. In the disconnecting position of the valve 43 the lever 23 occupies a fixed position corresponding to the idle running position of the throttle. When the disc has not yet reached the disconnecting position and the throttle valve is opened, the section drops and the piston 58 is returned by its spring thereby increasing the richness of the mixture supplied. Lateral holes are provided in the tube 13.