Patent GB-708526-A (GB)
Title: Improvements in auxiliary starting carburetters for starting from cold and running in cold weather internal combustion engines
IPC: F02M1/04
Filed: 1950-12-08
Abstract: 708,526. Spray carburetters. SOLEX Dec. 8, 1950 [Dec. 10, 1949], No. 30136/50 Class 7(3) In an auxiliary starting carburetter including a well supplied on the one hand with air and on the other hand with fuel supplied by the constant level chamber of the main carburetter through a calibrated orifice, the well being connected to the induction pipe on the downstream side of the throttle of the main carburetter by a conduit fitted with a valve member, whereas the upper part of the well communicates through a venting orifice with the atmosphere or with the air intake of the main carburetter either directly or through the constant level chamber, the effective area of the venting orifice is varied in accordance with the value of the suction existing on the downstream side of the throttle of the main carburetter so that this orifice is at least partly closed thus increasing the richness of the mixture supplied by the auxiliary carburetter when this suction is zero or low whereas this orifice is fully open when the suction exceeds a predetermined value. In Fig. 1 a suction actuated valve 24 controls communication between the upper part of an auxiliary carburetter fuel well 10 and the upper part of a constant level chamber 5. During starting with the auxiliary carburetter with the throttle valve 4 closed and the engine being turned by the starter motor the suction is insufficient to open the valve but when the engine is started the valve is drawn off its seat and the mixture supplied by the auxiliary carburetter is correspondingly weakened. When, however, the throttle valve 4 is opened the suction is reduced and the valve 24 tends to close and the mixture is enriched as is desired. The valve 24 may co-operate as shown with an elastic device such as a spring 25 or with an adjustable bimetallic strip. The latter controls the valve so that the mixture is not enriched as much when the temperature is increased. The valve takes up a position dependent on the temperature. In a modification, Fig. 3, a valve 33 which corresponds to the valve 24 is connected to a dashpot piston 35 which delays the movement of the valve by the suction created when the engine is started and thus delays the weakening of the mixture and prevents stalling of the engine. The valve 33 is urged to a certain position by the bimetallic strip 30a. It co-operates with a calibrated orifice 32. The bimetallic strips may be subjected to the temperature under the engine hood or a temperature which depends on that of a part of the engine for instance by placing these strips in an air stream previously heated by the exhaust pipe of the engine or which has been used for cooling the whole or a part of the engine. The valve operating piston such as 24 or 24c may be replaced by a diaphram metallic bellows &c. The bimetallic strips may be replaced by alternative thermostatic devices such as a metallic deformable box bellows &c. It is stated that the passage 23 may connect to the chamber 15 instead of to the induction pipe. In another modification, Fig. 4, the suction in the well 10 is used to control the valve 39 and acts directly upon this valve. A spiral shaped spring 30a is initially adjusted so that the valve 39 more or less stops the orifice 32. It may be adjusted so that the orifice has a portion of its section cleared when the engine is being driven by the starter. The spring may be replaced by a bimetallic strip. The top of the chamber 5 may be connected to atmosphere instead of to the induction pipe. The auxiliary carburetter shut off valve 16 may be manually or automatically controlled.