GB327111A - Improvements in or relating to charge forming devices for internal combustion engines - Google Patents

Abstract

327,111. White, A. E., (Delco-Remy Corporation). Sept. 22, 1928. Spray carburettors. -An air chamber having an inlet from the atmosphere is connected to one or more primary air and fuel mixing chambers, and also to one or more secondary mixing chambers, and further is placed in communication with the fuel supply passage to the primary mixing g chambers so as to make the static suction in the said air chamber the dominant factor controlling the fuel flow to the primary chambers. An air manifold 20 has branches 24 connected to the engine cylinders, and into each branch, which constitutes a secondary mixing chamber, rich mixture is delivered through tubes 334 from primary mixing chambers 90, Figs. 2 and 4, located in a casting 28, Figs. 1 and 2, to which the air manifold flange 26 is secured by bolts 86. Secured also to the casting 28 is a frame 30 containing dashpots, and forming the top of a float chamber 38. Fuel is conveyed to the primary mixing chambers through an elbow passage 70, Fig. 5, leading to a canal 82, Figs. 4 and 5, which communicates through calibrated plugs 84 with passages 86, Fig. 2, each of which delivers fuel through orifices 96, 102, Fig. 2, into a primary mixing chamber 92. The lower end of passage 70 has a metering plug 74 which provides the normal fuel supply, but under certain conditions a valve 76 is lifted to augment the supply. Each passage 86 communicates with the air chamber 94 through a horizontal passage 98 of larger area, and a vertical passage 104. The fuel orifice 102 is at the end of the passage 98, is of restricted area, and supplies fuel at the higher speeds, the low speed supply taking place through the orifice 36. With the passages arranged and proportioned in the manner described, the fuel flow is determined mainly by the static suction existing in the air chamber 94 and passages 104, 98. The primary mixture is conveyed from the chambers 90 to the pipes 334, and the flow is controlled by a primary throttle valve 106, Figs. 2 and 4. Air is admitted to chamber 94 bv a valve 126 loaded by a spring 128, the compression in which can be varied by a lever 146, Figs. 3 and 6, acting upon the flange 144 of a sleeve 142. The valve 126 may be prevented from opening at starting by compressing the spring to its fullest extent, but as some air is necessary to carry along the fuel, this small amount of air is admitted through a space 152, Fig. 6, formed between a fiat on the boss of lever 146 and the wall of casting 28. This space disappears when the lever is moved to ease the compression in the spring. The normal inoperative position of the choking lever 146 is determined by a set screw 154, Fig. 1, screwed into a lug 156, Figs. 3 and 6, and adapted to engage the wall of casting 28. To prevent fluttering of air valve 126, and to retard its opening movement for accelerating purposes, a dashpot comprising a piston 162 in a cylinder 160 is provided. The piston is slidably mounted on a sleeve 164 secured to the valve stem 132, and is normally forced by a spring 171 against an annular rib 170 on the flange 168 of the sleeve. Holes 176 for the escape of fuel are provided in the bottom of the piston. The bottom of the cylinder is closed by a cap 180 having an aperture 182 and a non-return valve 184. The flow of air through the secondary passage 22 is controlled by two valves, one 186 actuated by, and after a predetermined movement of, the primary throttle 106, and the other 188 pivoted out of centre on a shaft 192 and actuated by suction. The movement of valve 188 is retarded by a dashpot similar to that applied to the air inlet valve 126, the dashpot piston being attached to rod 234. Further, a yielding connection may be provided between the valves 186, 188 to control the movements of the latter. The air valve rod 132, Fig. 4, passes through one of the primary mixing chambers, which is enlarged at this point to prevent increase in velocity of the mixture. In a modification. Fig. 7, the fuel passage 86 communicates with the air chamber through a right-angle passage 104, 362. Specifications 327,107 and 327,123 are referred to.