Patent GB-164378-A (GB)
Title: An improved carburettor and method of controlling the feed of liquid fuel
IPC: F02M1/00
Filed: 1919-09-06
Abstract: 164,378. White, A. E., (Stromberg Motor Devices Co.). Sept. 6, 1919. Spray carburettors. - Fuel is aerated end sprayed by a nozzle to which it is supplied from a reservoir which is open to atmospheric pressure and also to pressure less than atmospheric, the operation of one of these pressures being controlled. As applied to an aeroplane carburettor, two such nozzles are mounted one on each side of a common float chamber 17 containing an approximately cylindrical float attached to a lever 24 pivoted at 30. The fuel inlet 45 is closed by a valve 46 with a hollow stem connected to a pin 28 on the lever 24 by a spring bolt 37, to prevent chattering. The shape of the float and its closeness to the valve reduces interference with the action through fore and aft inclination of the carburettor. A passage 92 supplies air to atomizing ports 77 in the nozzle and to an annular accelerating well 64 round the nozzle. Ports 72 in the walls of the well 64 and ports 73 in the nozzle walls connect the accelerating well with the fuel space 63 below the nozzle, to which space fuel passes from the float chamber through a plug 60 which can be replaced, so as to alter the rate of supply. The position of these plugs 60 allows a large angle of inclination sideways without either passage being uncovered to the atmosphere. The air admitted through the ports 77, by reducing the effective suction at the nozzle, increases the relative effect of adjusting the relief valve 107. Modified nozzles are described in which the wall of the nozzle also forms the wall of the accelerating well. In one form an axial rod is used to prevent the formation of bubbles, in another a restricted passage at the base of the nozzle is provided for the same purpose. The nozzle is surrounded by an inner choke tube 87 supported on an outer choke tube 85 by means of notched arms 89 and a spring ring 90. Suction is maintained in the float chamber by means of ports 95, 96 and can be relieved partly or wholly by a plate valve 107 rotatably adjustable by means of a lever 118 held by a spring pawl 120. The valve 107 is arranged in a valve chamber 103, to which air enters by passages 105, 104 and then passes through ports 124, 125 in the valve. Variations of the position of the ports 96 may be used to alter the suction in the float chamber. For slow running, fuel from the well 64 rises through a passage 135 and issues past a needle valve 129 through a vertical slot 140 extending above and below the closed position of the throttle 13. For starting, a hand-operated priming plug-valve 146 is provided, a leaf-spring being arranged to hold it open or closed by pressing on a hexagonal cam formed on the plug. Where more than two float chambers are used, one may be sealed and connected to the other so as to form virtually an extension thereof. Or a small central chamber carrying the pressure-relieving valve 107 may communicate with each of several sealed float chambers. A draining well 158 with an escape pipe is provided. Fig. 19 shows a modified construction in which the float chamber is behind the two carburettors, which are brought close together so that both throttles can be mounted on the same spindle. The fuel inlet to the float chamber has a conical wire strainer held by a spring to prevent rattling. The slow-running port 140 is supplied with fuel from the accelerating well through a tube 141 and with air through a port 185 past a valve 129<1> which can be adjusted by means of a screw driver and is provided with a friction ratchet comprising balls 190 held apart by a spring and engaging in longitudinal grooves in the bush 188. Air for the atomizing ports enters by way of a port 180 in the main air inlet and by passages 79', 78. Air enters the float chamber through a passage 202 and screen 204, Fig. 21, and the relief valve 107 is replaced by a hand-operated sleeve valve 193 which controls the suction through the port 96, Fig. 19; these ports communicating with a passage 95<1>, Fig. 21. The valve 193 may be replaced by a valve 218, Fig. 27, operated by a device 214 sensitive to changes of temperature and pressure, and comprising a receptacle which contains air at sea-level atmospheric pressure together with a small quantity of a vapour of a volatile liquid. The valve spring 229 is adjustable by hand by means of a lever 228 and a pin and slot or quick-threaded screw connection between the sleeve 219 and the surrounding casing 210. The valve 218 has an adjusting ratchet similar to that used with the valve 129<1>.