Patent GB-327125-A (GB)
Title: Improvements in or relating to charge forming devices for internal combustion engines
IPC: F02M7/06
Filed: 1928-09-22
Abstract: 327,125. White, A. E., (Delco-Remy Corporation). Sept. 22, 1928. Divided on 327,107. Spray carburettors. - In a charge forming device in which rich mixture is supplied from a common distributor or primary carburettor 26 to one or more secondary carburettors located near the intake ports of the engine, provision is made for supplying additional fuel during acceleration. Each secondary carburettor, of which Fig. 2 shows one in section, is located within a branch pipe 21, 22, Fig. 1, and comprises a Venturi 105, a fuel nozzle 114 and an annular chamber 110 surrounding the Venturi. Secondary air is supplied through a manifold 20, whilst the mixture of fuel and primary air enters the annular chamber 110 from the primary carburettor 26 through ducts 67 and 68 and radial holes or slots 100, 101 leading from intermediate chambers 98 to the interior of a hollow screw 99 located vertically above the nozzle 114, and thence into the Venturi through holes 111 and nozzle 114. The secondary air supply is controlled by a spring- loaded valve housed within the main air intake 23. Interconnected throttle valves 25 are fitted between each mixing chamber and its respective coupling member 90, 91, the latter being in mutual communication through a pressurebalance tube 180. Fuel is drawn through a duct 48a in a projection in the cover 27 of a common float chamber 30 to a transverse channel 61 in a distributor block 58 from which the ducts 67, 68 lead to their respective secondary carburet. tors. The inflow ends 65, 66 off each main duct 67 and 68 open into a common well 69 from which primary air is drawn to facilitate the flow of fuel to the secondary carburettors. In the distributor block 58 is a fuel well 76, the upper end of which communicates with the ducts 67, 68 through a hole 79 and a transverse channel 72 in a cover 73 and two vertical passages 70, 71 located one at each end of the channel. The bottom of the well 76 communicates with the interior of the float chamber 30 through ducts 77 and 53 leading to a chamber 52 formed in the projection of the float chamber cover below the fuel level. A further duct 54 connects the chamber 52 with a second transverse channel 62 in the distributor block 58, this channel also communicating with the main fuel supply ducts 67, 68. A disc valve 57 is provided in the chamber 52, the disc seating on the end of a hollow screw plug 50; a second seating is provided at the end of the duct 54. When on its lower seating the disc valve cuts off communication between the chamber 52 and interior of the float chamber but when raised against the upper seating the duct 54 is cut off from the chamber 52 but a free passage is open from the float chamber through the chamber 52 to the duct 53. When the depression transmitted to the duct 54 reaches a certain value the disc valve is raised and the depression in the well 76 causes the well to fill with fuel drawn from the float chamber through duct 53. This action occurs during acceleration and at an engine speed corresponding to vehicle speeds exceeding 15 m.p.h. When the suction is low, as during closing movements of the throttle, the disc valve drops and the contents of the well flow under gravity to the main fuel ducts 67, 68, assisted by an air bleed port 80 in the distributor block cover 73, via the ducts 53, 54 and channel 62. The excess fuel thus supplied to the annular chambers 110 of the secondary mixing chambers accumulates in wells 115 provided below the nozzles 114 of each chamber in readiness for the opening of the throttle valves. During acceleration, the emptying of the wells is facilitated by an air bleed port 125 which admits air below each accelerating well. Each well is normally closed by a disc valve 123. This valve is retained on its seating during closing movements of the throttle, as when the accelerating well is filling, by the depression transmitted from the engine side of the throttle valve through a passage 126 which is provided with a ball valve 128 at the intake end to prevent air being drawn through this passage to the well when the latter is emptying. A small quantity of fuel is retained in the intermediate chamber 98 owing to the location of the lowest hole 100 in the hollow screw 99, this hole being slightly above the level of the bottom of the chamber. By this means a fuel relay is provided for the purpose of maintaining the fuel supply to the Venturi when the air flow through the latter has been greatly reduced, as on suddenly closing the throttle, the additional fuel supply flowing under gravity through passages 112 and 113 to an intermediate point in the wall of the Venturi between the radial holes 111 and the throttle valve.