Patent GB-586270-A (GB)
Title: Floatless carburettors for internal combustion engines
IPC: F02M69/00
Filed: 1940-06-17
Abstract: 586,270. Fluid-pressure servomotors. SOC. ANON. SOLEX. June 17, 1940, No. 10480. Convention date, June 17, 1939. Addition to 443,933, [Group XXVII]. [Class 135] [Also in Group XXVII] In a floatless carburetter as described in the parent Specification, having the fuel delivered to a chamber 16 maintained at the same pressure as the air inlet 3 by a conduit 17, the fuel being controlled by a needle valve 9 connected to the throttle 2, the delivery of fuel is corrected in accordance with the difference in pressure at opposite sides of the throttle 2, or with the absolute pressure in the intake pipe, or both. The connection 37, 39, 42 between the throttle-operating arm 5 and the needle 9 maintains the sectional area for inlet of air proportional to that for inlet of fuel, and in addition, the arm 39 is connected to a diaphragm 43 subjected to the pressures on opposite sides of the throttle by passages 45, 47. A point in the intake pipe, for example the inlet 3, is connected to a capsule 30 which acts on the byepass valve 22 of the fuel pump 12, so that the fuel pressure in the conduit 11 varies in accordance with the temperature, pressure and density at the point. A supplementary enrichment of fuel is obtained at high powers by a connection 49, 50, 51 to a capsule 52 subjected to the pressure existing on the down-stream side of the throttle 2. When the throttle is at slow-running position, a connection 65, 66 lifts a lever 26 controlling the byepass valve 22 out 'of the range of the capsule 30, so as to maintain the fuel pressure in the conduit 11 constant. For stopping the engine, the pilot's lever 7 is moved beyond the slow-running position, as allowed by a lost-motion connection 56, thereby bringing an abutment 63 into contact with a valve 59, the opening of which causes the diaphragm 43 to close the needle 9. An accelerating-pump comprising a diaphragm 31 may be arranged as shown, and a heater 55 may be provided on the conduit 17. To prevent fluctuations of pressure in the suction pipe 13 of the fuel pump from affecting the pressure in the conduit 11 .through the byepass valve, this valve may be connected to a diaphragm which is acted on at one side by the pressure in the conduit 11, and on the other side by atmosphere pressure and by the spring 23 connected to the lever 26; or the spring may be omitted. In other forms, the capsule 30 acts on the lever 26 through a cam, or the lever 26 may be two-armed, one arm being connected to the capsule 30, and the other to a similar capsule acted on by the pressure downstream ot the throttle 2. In another form, the lever 39 may be connected directly to the capsule 52, and the diaphragm 43 omitted, the pilot's lever then acting on a' cock in the conduit 15 to shut off the fuel for stopping. In another modification, the capsule 30, instead of controlling the byepass valve, acts on a diaphragm forming an expansion chamber for the fuel in the conduit 11 ; or the capsule may act on a toggle connection between the capsule 52 and the lever 50. In a further form, the capsule 52 is replaced by a diaphragm, and the throttle 2 is controlled automatically according to the intake pressure acting through a servomotor. Other forms are arranged for use with superchargers, either before the air inlet 3, or between the throttle 2 and the engine. Also the needle 9 may be replaced by a cylindrical slide formed with a tapered notch.