Patent GB-374090-A (GB)
Title: Improvements in fuel-supply systems for carburettors of internal-combustion engines
IPC: F02M1/00
Filed: 1930-11-21
Abstract: 374,090. Spray carburetters; pumps for liquids. ROCKWELL, E. A., 1826, Diversey Parkway, Chicago, U.S.A. Nov. 21, 1930, No. 35154. Convention date, Nov. 25, 1929. [Class 7 (iii).] Fuel is supplied to a carouretter by a pump the forcing stroke of which is effected by resilient means, the dry side of the pump being connected with the intake manifold beyond the throttle whereby the fuel delivery is controlled in accordance with the pressure in the manifold which acts in opposition to the resilient forcing means to vary the delivery stroke. The pump, which is of the flexible-diaphragm type, consists of castings 10, 14, Figs. 2 and 3, between the flanges 12, 13 of which the diaphragm 15 is secured, so as to produce a delivery chamber 16, and a chamber 17 on the dry side normally at atmospheric pressure. Fuel enters through passages 19, 21 to a visible filter chamber 23 and then is drawn past valve 26 into chamber 16, and, on the forcing stroke, is delivered past valve 27 to outlet 29, a vapour dome being provided at 30. The flexible diaphragm is held between a recessed disc 32 and a spring cap 33 which are clamped together by a nut 35 and washer 34. A plunger 36 attached to the diaphragm is guided at 37, and its reduced lower end carries loosely a spool 40 engaged by a yoke portion 42 of a bell-crank lever pivoted at 44, the other end 45 of the lever being forced by a spring 47 against an engine-driven cam 46. The suction stroke of the pump diaphragm is therefore effected by the cam, the forcing stroke being produced by the spring 38. In order to control the pump delivery, the chamber 17 is connected by a control tube 52 with the induction passage on the engine side of the carburetter throttle. Thus, with throttle closed the chamber 17 becomes more or less exhausted, and the effective force of the driving spring 38 is reduced. As the throttle is opened to accelerate, the pressure in chamber 17 increases and so therefore does the force of the spring 38, with a consequent increase of fuel supply. To regulate the action of the control tube, a breather orifice 50 may be provided in a removable plug 49. In Fig. 4, the pump draws fuel from a low level tank through a pipe 251 and delivers it through a pipe 276 and past a float valve 297 to a float chamber 277 which supplies the nozzle 282 of a down-draught carburetter 284. The load control tube 289 opens on the engine side of the throttle 285, and is provided with an air inlet controlled by a valve 288 actuated, through link 287, from the air choke valve 286 to vary the degree of vacuum on the dry side of the pump.. A downdraught carburetter in which fuel is supplied directly to the nozzle is shown in Fig. 6. A pipe 183 from the fuel pump delivers to a chamber 181 communicating through duct 185 with a chamber 186 whence it passes a valve 193, to a passage in a transverse nozzle member 178 and is discharged into the air stream at 179. The movement of valve 193 is limited by an adjustable stop 188. In Fig. 7, the load control tube 236 is shown connected to an idling passage formed as a small Venturi 232 which receives fuel from chamber 181, Fig. 6, through a duct 227, the idling mixture being discharged at 234 on the engine side of the throttle. The chamber 238 is in communication with the atmosphere through a calibrated orifice in a removable plug, and also through a duct, Fig. 5 (not shown), adapted to be controlled by the spindle of the air choke valve 173, Fig. 6. The fuel tank may be above the level of the pump and the engine may be of the supercharged type. The Specification as open to inspection under Sect. 91 (3) (a) describes also the following : A fuel pump, Fig. 5 (Cancelled), in which the lever for actuating the diaphragm is dispensed with, the cam 86 acting directly upon a button 85 mounted in a member 82 carried by the plunger rod 83. Two springs, an intake spring 80 and a feed spring 87, are employed the latter being mounted between the member 82 and a shoulder 88 on the plunger 75. Both strokes of the pump are effected by springs. The diaphragm 55 is vertically arranged, and the load control tube 90 is connected to the dry side at 89. Fuel enters a visible filter chamber 67 and is drawn therefrom past a valve 72 and delivered past an outlet valve 60. The load control tube may be arranged as a Pitot tube 114, Fig. 7 (Cancelled), which shows a downdraught carburetter to which fuel is admitted by a pipe 112 and air by an inlet 103, a throttle being provided at 105. The load control tube itself, or air openings thereinto may be controlled by screwed needle, or spring-loaded valves. In another form of downdraught carburetter, Fig. 11 (Cancelled), air entering at 133 is controlled by a valve 134, and a throttle is provided at 150. Fuel is supplied through a pipe 140 and is controlled by a conical valve 144 loaded by a spring 147 located in a tube 137 having spraying orifices 148. The valve has a permanently open duct therethrough for idling, and the idling fuel is discharged through an aperture 149 near the edge of the throttle valve. A load control tube 153 terminates in a Pitot tube extension 155 and air may be drawn into the tube through an orifice controlled by a spring-loaded valve. In the carburetter shown in Fig. 6; the valve 193 is actuated by a diaphragm 196 loaded by a spring 198, and subjected to vacuum through the fuel duct. The position of the fuel valve is also determined by that of the throttle, a cam 207 on which actuates lever 204 which is forced against the cam by a spring 208 and whose upper end engages a spool-shaped collar 210a. When the throttle is closed, the fuel valve is also closed. A duct 200 in the nozzle member, which is of streamline form, serves as a drain for fuel from the diaphragm chamber. For idling, fuel passes from chamber 181 through ducts 213, 214, Fig. 17 (Cancelled), valve 216 and passage 226 to passage 227, Fig. 7. The valve 216 has a squared section 217 and is actuated by suction transmitted to a diaphragm 224 exposed on its exterior to atmosphere. A modified form of load control is described in connection with Fig. 23 (Cancelled). A casting 261 has a connection at 262 with the intake manifold and, at 265, with the load control tube. A valve 269 controls air entering at 267 and is connected to the air choke of the carburetter. For delivering an accelerating charge a chamber 290, Fig. 4, is provided and connected with the float chamber 277 through a tube 291 with constriction 292. The chamber contains two cupshaped. plungers 293, 299 loaded by springs, the position of the plunger 293 being determined by a stop 295 and shoulder 298. Tubes 297<1>, 302 communicate with the carburetter passage above and below the throttle 285. In the positions shown, the accelerating chamber becomes filled with fuel. If the throttle be opened to accelerate, the vacuum above plunger 293 is destroyed, the plunger is forced down by its spring and a charge of fuel is delivered through tube 302 to the orifice 303 in the throat of the Venturi section. The plunger 299 returns to its former position. This subject-matter does not appear in the Specification as accepted.