GB387230A - Improvements in spring carburettors for internal combustion engines - Google Patents

Abstract

387,230. Spray carburetters. JENNINGS, J. T., 35, Wharf Road, King's Norton, Birmingham. June 30, 1932, No. 18463. [Class 7 (iii).] In a carburetter having a loaded valve controlling the admission of both the secondary air and the primary mixture to the mixing chamber, a port or ports are arranged annularly around the valve and deliver primary mixture into a passage or choke located between the valve and its surrounding structure. The outer casing consists of a tubular part 1 containing a throttle valve 23 and a cylindrical part 2 which is of greater diameter than the first part and houses a liner 4, the curved and tapered inner surface of which is concentric with the casing part 2 while the outer surface thereof is eccentrically disposed in the casing to leave a crescent-shaped chamber. This chamber has a maximum width in its lowest part where there is provided an inlet passage 8 for primary mixture formed when air is sucked through an annular channel 38 around a fuel nozzle 37 into a venturi-shaped choke tube 25 formed in a lower part 26 of the carburetter. An annular projection 27 on the part 26 locates a primary mixture regulator 29 formed with an aperture 32 coaxial with the passage 8 and grooves 33, 34 extending radially from the aperture. In the starting position of the regulator, the grooves 33, 34 coincide with passages 35, 36 in the casing 2 and allow some of the primary mixture to byepass a primary mixture throttle valve 41, the rest passing through small apertures in the valve. Sudsidiary air is added to the mixture through ports 45 manually closable by a slide 46. An additional controlled byepass may be provided between the passage 8 and one of the ports 45, the groove 34 in the regulator 29 being extended radially and circumferentially to provide for this. The mixture thus formed passes into a space 13 between the end of the liner 4 and an inturned lip 9 on the casing 2 and thence into a mixing chamber 14 through a series of ports or a narrow annular port 12 between the lip 9 and the liner 4. The lip 9 constitutes a flared opening 10 for the admission of secondary air. At starting, it is closed by a bulbous head 18 on a hollow valve member 17 drawn outwards along a fixed sleeve 16, secured to a bridge 15 on the casing 2, by a spring 19 operating between the closed end of the sleeve 16 and a dashpot piston 20 on a screwed rod 21 the head of which engages the head 18. The valve 17 may be controlled by gravity or by several springs acting in succession. As the engine suction increases, the valve is drawn inwards providing an annular passage adjacent the annular port 12 and of increasing area for the secondary air. A pin 43 secures the primary mixture throttle valve 41 to the head 18 so that inward movement of the air valve 17 slides it along the casing. For normal running, the regulator 29 is rotated to close the passage 36 and the primary mixture throttle valve 41 is displaced by the air valve 17 to close the passage 35 and, by reason of a recess formed in its end, uncover the passage 8. With wider throttle openings, a crescent or other shaped constriction 39 in the passage 8 chokes the flow of primary mixture and to adjust the air inlet accordingly, a plate 48 secured to the rod 21 is adapted to close the ports 45 when the valve 17 is fully open. Unvaporized fuel in the mixing chamber 14 is carried away by air sucked in through one or more openings 56 or, for slow running, a port on the engine side of the throttle valve 23 may be connected to the fuel supply at its lowest point.