Patent GB-491806-A (GB)
Title: Improvements in or relating to carburettors for internal combustion engines
IPC: F02M1/16
Filed: 1937-03-08
Abstract: 491,806. Spray carburetters. PIESTRAK, C. S. March 8, 1937, No. 6838. [Class 7 (iii)] An annular regulating device controls the main air admission around an air nozzle which delivers a converging jet of air on to a conical jet of fuel issuing into a convergentdivergent element from an annular passage formed between a fuel nozzle and a needle valve. As shown in Fig. 1, fuel, fed from a floatchamber 1 or from a reservoir below the nozzle, to a chamber 2 is discharged through a conical bore 6 in the fuel nozzle 5 and controlled by a needle valve 10 which is moved axially when a pinion 13 is rotated by a rack 20. To compensate for changes in the temperature or pressure of the air, a small needle valve may be fitted inside the valve 10 and controlled by a barometric or thermally sensitive device. The fuel nozzle 5 is surrounded by a conical air passage 22 and discharges into the throat of a Venturi tube 28 which is secured in the intake passage by a flanged nut 30. The air supply to the Venturi tube is regulated either by an axially movable cone surrounding the nozzle or by controlling openings 32 in the nut 30 by openings 36 in a rotatable disc 35 forming the base of a cylindrical sleeve 37. The floatchamber 1 and nozzle 5 are secured to the intake passage by a single retaining element 51. In the construction shown in Fig. 2, the needle valve 10 is moved axially without rotating by a pinion 42 meshing with a pinion 41 on a sleeve 12 which engages a screwed collar 11 on the valve 10 and is prevented from moving axially. The crosssection of the fuel passage in the nozzle is controlled independently of the needle 10 by the conical end 8c of a sleeve 8a which is secured to a ring 46 and moved axially as the ported disc 35 is rotated. The needle valve 10 may be moved axially by the engagement of fingers on the sleeve 8a with projections on the sleeve 12, instead of by the pinions 41, 42. The fuel passes through a removable filter 58 before entering the floatchamber 1 which contains a cylindrical float 55. In another construction, the needle valve is held against rotation by a hexagonal part 17a, Fig. 8, and is moved axially by pinions 41a, 42a which rotate a threaded sleeve 12a in mesh with a threaded collar 11a on the valve. During a part of the rotary movement of the ported disc, levers (not shown) rotate a plug 70 to move the sleeve 12a axially and to control the needle independently of the pinions 41a, 42a. In the construction shown in Fig. 13, the needle 10 is moved axially by an eccentric 102 on a shaft 103 and the Venturi tube 28 is secured to a ported disc 108 which is rotated to control the admission of air through openings 109. Rotation of the disc also opens extra-air admission ports 110 and rotates the head of the nozzle to enable a tube 104 having a conical part 104d to be moved axially to control the cross-section of the fuel passage independently of the needle valve 10. An additional fuel control may be obtained by making the walls of the tube 104 slightly conical adjacent a projecting edge 115a in the nozzle, and a chamber 116 between the edge 115a and the discharge orifice 117 allows a reserve of fuel to collect to facilitate starting and slow-running. The air inlets 23 to the conical air passage 22 are controlled by a screwed pin 112k and by ports 112a in a sleeve 112 secured to a non-rotating part of the nozzle. The needle valve may have a central air inlet passage. The carburetter may be provided with float chambers for light and heavy fuels, connected to the nozzle by passages containing spring-pressed valves, one of which is opened by a rocking lever as the other is closed.