Patent GB-459726-A (GB)
Title: Improvements in carburetters for internal combustion engines
IPC: F02M19/00
Filed: 1935-07-16
Abstract: 459,726. Spray carburetters. LINGA, T., Kokomo, Indiana, U.S.A. July 16, 1935, No. 20316. [Class 7 (iii)] In a carburetter in which an induction passage containing an air inlet valve is connected by a fuel conduit with a fuel chamber, the valve is governed by the float when the float approaches its lowest position to maintain a suction in the fuel chamber, and the valve automatically conforms to the various fuel lifting requirements to lift fuel into the chamber under the then existing conditions. Fuel from a main supply is drawn by suction past an inlet valve 73, directly secured to a float 74, into a float chamber 24 in which the float is guided by a hollow post 23. Within the post 23 slides the stem 55 of a fuel needle valve 56, the upper end of the stem being provided with a head 53 engaged by a lever 51 the opposite end of which is linked to an unbalanced air inlet valve 34. The air valve operates in an inlet 31 leading past a pair of Venturis 38, 39 to a mixing chamber 29. The edge of the heavier side of the air valve 34 turns upwards to ensure an adequate response to the air flow when in wide open positions and the opposite edge is reversely curved to co-operate with an obstruction 35 and avoid a Venturi effect at the valve. At its lower end, the stem 55 carries a cross-bar 61 disposed in a slot 66 in the post 23 and the cross-bar supports a ring 63 movable with a dashpot action in a well 64 at the foot of the float chamber, the weight of the ring and valve parts tending to close the air valve against the suction of the engine. The top of the float chamber communicates through a port 83 with a Venturi 44, 45 at a point remote from the greatest constriction thereof and the Venturi 44, 45 opens into the Venturi 39, air being supplied through a slot 47 in the air inlet 31 and a chamber 46 housing the lever 51 and valve-stem head 53. If the suction is insufficient to draw fuel into the float chamber, the fuel level therein falls and the float de. scends and engages the cross-bar 61 to provide additional weight to close the air valve and increase the suction. Fuel flows from the float chamber past the valve 56 to a chamber 75 in the post 23, up passages 76 and an annular chamber 77 to a second annular chamber 78 at the throat of the Venturi 44, 45. As the suction at this throat decreases with wider air inlet openings, a constructed portion 84 of the stem 55 allows air to bleed into the float chamber through apertures (not shown) in the post 23 to maintain the head of fuel. At starting, a conical valve is rotated to put the float chamber into direct communication with the annular chamber 77 and admit an adjustable flow of air into the float chamber to increase the head of fuel. Opening the throttle, operates an acceleration pump 92, Fig. 9, which supplies fuel to a nozzle 108 opening into the Venturi 44, 45 level with the port 83 and also to a reservoir 112 connected at its opposite end with that Venturi by a passage 113. Further to reduce the suction in the float chamber when the engine is cold, an air inlet 143, Fig. 11, is controlled by a rod 144, having a smaller coefficient of expansion than the adjacent float chamber metal, which is manually forced down a passage 141 until its head 145 closes the top of the passage ; the first heating of the carburetter lifts the rod, which on cooling leaves the passage open and thereafter controls the opening.