Patent GB-798720-A (GB)
Title: Improvements in internal combustion engine carburettors including a thermosensitive control auxiliary starting device
Inventor: MENNESSON ANDRE LOUIS
IPC: F02M1/04
Filed: 1956-10-29
Abstract: 798,720. Carburetters. SOC. INDUSTRIELLE DE BREVETS ET D'ETUDES, S.I.B.E. Oct. 29, 1956 [Nov. 2, 1955], No. 32952/56 Class 7(3) A carburetter including an auxiliary device, the distributing valve of which is controlled through thermosensitive means, this auxiliary device being for starting and running the engine in the cold state by forming and supplying into the induction passage of the carburetter downstream of the throttle valve thereof, a rich mixture constituted on the one hand by fuel possibly emulsified with air in advance and on the other hand by auxiliary starting air, the displacement of the distributing valve in the closing direction ensuring a reduction of the flow rate of air and fuel mixture and possibly an increase of the proportion of air in this mixture, comprises a mechanical locking device controlled by a pneumatic system responsive to variations of the suction existing in the induction passage downstream of the throttle valve for preventing the distributing valve from being wholly closed due to the heating of the thermosensitive means as long as the suction has not dropped below a predetermined value. The engine may be kept at accelerated idling conditions and the arrangement permits during very cold weather of bringing the engine to its working temperature and in the case of automobile vehicles of operating the heating system of the automobile when this system is working by interchange of heat with the engine. Referring to the Figures, the edge of the distributing valve 9 is provided with a projection 44 which co-operates with the middle portion of a lever 45. The free end of the lever bears under the effect of its own weight on the top of a piston 33. When the bimetallic strip 29 has been heated and the dsitributing valve has come into the position of Fig. 3 the distributing valve 9 is kept stationary by the lever 45 which has come across the oath of projection 44. The engine is then running at a speed higher than normal idling speed (accelerated idling). The piston 33 is advantageously arranged in such a manner that it simultaneously and inversely varies the respective cross-section for the flow of air and that of fuel supplied by the auxiliary starting device independently of the position of the distributing valve 9. For this purpose the inlet conduit 7 is divided into two successive portions disposed in such manner with respect to the piston 33 that the piston can permit a free communication between these two portions when it is in the position corresponding to the maximum suction in conduit 8, Fig. 3, and closes this communication for its other end position. There is provided a conduit 36 one end of which opens into the surface 17 through an orifice 21 capable of being placed in communication through groove 25 with the orifice 18 of the fuel inlet conduit 6 when the distributing valve is in its position corresponding to the lowest temperatures of the bimetallic strip 29, the other end of the conduit 36 opening into the cylindrical recess 32 at a level such that this last mentioned end is cleared by piston 33 when the piston is in its end position for which it closes conduit 7 but that it is closed by the piston 33 when the piston occupies its other end position, Fig. 3. In this last mentioned position the passage between conduits 36 and 34 only takes place through a calibrated orifice 37 extending through the wall of the piston at the level of the peripheral groove 38. The edge of the distributing valve 9 carries a projection 47 the side of which corresponding to the opening of the valve is substantially radial. This projection 47 co-operates with a push piece 48 freely slidable in the casing 27, the outer end of the push piece being disposed across the trajectory of lever 49, rigid with the spindle of the throttle valve 4. The push piece may be moved into a position in which it prevents the distributing valve from being brought back into action as a consequence of the drop in temperature of the air stream which flows on the bimetallic strip 29. The piston 33 might be replaced by a deformable diaphragm on which the lever 45 would bear.