GB610046A - Improvements in and relating to acceleration pumps for carburettors of internal combustion engines - Google Patents

Abstract

610,046. Spray carburetters. SOC. ANON. SOLEX. Aug. 25, 1945, No. 21837. Convention date, March 4, 1944. [Class 7 (iii)] An acceleration pump for a carburetter is operated mechanically on opening of the throttle valve, but returned by the suction at the engine side of the throttle valve and a valve in the pump discharge passage is spring-loaded so that it cannot be opened by the force of the spring alone acting on the pump diaphragm, the fuel remaining in the pump on stopping escaping to the float chamber. Provision is also made for enrichment of the fuel mixture at full throttle. The pump comprises a diaphragm 16 with a fuel chamber 27 having inlet and delivery valves 13, 15 and a chamber 26 connected by pipe 17 to the engine side of the throttle valve 2, rapid opening of which actuates a lever 20 and a rod 18 to move the diaphragm 16 to expel fuel through an auxiliary nozzle 10. On subsequent closing of the throttle, the diaphragm 16 only moves to the right if there is sufficient suction in the chamber 26, eliminating waste of fuel when the engine is stopped. A spring 29 urges the diaphragm 16 to the left to empty chamber 27 slowly by leakage past valve 13, when the engine stops, the valve 15 remaining closed. In a modification, Fig. 4, the diaphragm 16 is replaced by two diaphragms 16<1>, 16<2> of different areas enclosing a space 26<1> subject to the suction by pipe 17. The emptying of chamber 27 when the engine stops is facilitated by a small orifice 31 byepassing the valve 13. To prevent movement of the diaphragm to the right until a predetermined suction is set up, the inlet valve 13 may be spring-biassed to closing, or alternatively the diaphragm 16 may carry a valve closing a chamber to which the suction is transmitted, a high suction being necessary to open the valve to transmit the suction to diaphragm 16. Figs. 5-8 show the acceleration pump combined with a device to enrich the mixture at full throttle. In Fig. 5, the auxiliary nozzle 10 is normally closed by a valve 48 actuated by a spring-loaded diaphragm 47 subject to the pressure of the fuel in chamber 27 and to atmospheric pressure through conduit 55. Rapid opening of the throttle at small throttle openings temporarily opens the valve 48 to provide fuel for acceleration. At large throttle openings the diaphragm 16 contacts a movable finger 56 to hold the valve 48 open and fuel, sucked through the nozzle 10 opening in the venturi, provides a permanent mixture enrichment. In a modification, the nozzle 10 opens in the air inlet 11 and the acceleration pump discharges into. it through a non-return valve whilst a valve, normally kept closed by suction transmitted to the space between two diaphragms or by a spring, is opened at full throttle by an extension of the rod 18 to allow enriching fuel to flow through an additional conduit to the fuel well 3 of the main nozzle 5. In a further modification, Fig. 8, valves 60, 59, controlling the delivery of fuel for acceleration and enrichment respectively are actuated conjointly by a spring 39<1> tending to close valve 60 and by suction transmitted to the space between the diaphragms 36a, 36b tending to close the valve 59. At small throttle openings the valve 60 is opened by the high suction and rapid opening of the throttle discharges fuel through the auxiliary nozzle 10. At full throttle the valve 60 is closed and enriching fuel flows through a byepass conduit 62 and conduit 41<1> to the fuel well of the main nozzle 5. The Specification as open to inspection under Sect. 91 also describes a diaphragm acceleration pump which is not spring-loaded. This subjectmatter does not appear in the Specification as accepted.