GB775519A - Improvements in carburetters for internal combustion engines - Google Patents

Abstract

775,519. Carburetters. GENERAL MOTORS CORPORATION. June 6, 1955 [June 23, 1954], No. 16159/55. Class 7 (3). The choke valve is automatically and jointly operable by a device adapted to be responsive to engine intake suction but to be ineffective after a predetermined initial degree of opening of the choke valve is effected and by a temperature responsive device adapted to permit a further degree of opening of the choke valve after and at a rate slower than the initial opening and a final degree of opening at a rate higher than the slower rate. The suction posterior to the throttle valve is communicated through a passage 98 to the cylinder 96. The passage communicates with the cylinder by means of an orifice 100 of rectangular triangular or other shape. The choke valve cannot open very far before the orifice is completely blocked by the piston. The piston is slightly loose in the cylinder and when the piston reaches the dotted line A the area of the orifice 100 not covered by the piston 94 is very little greater than the leakage space so that air can enter the cylinder at almost the same rate as it is withdrawn therefrom through the passage 98. The choke valve will be moved to this position almost immediately after the engine starts. Heated air passing through the housing 78 progressively heats the bimetallic strip 86 the choke valve being moved to its open position. This movement will be relatively slow until the choke valve reaches a predetermined open position when the rate of movement will be considerably increased. To effect this increased rate of movement the piston 94 is cut away as indicated at 110 the cut away portion being brought into register with the orifice 100 when the choke valve is 55 degrees open at which position the suction communicated to the housing 78 is much increased and much larger quantities of heated air are drawn through the housing 78. The desired mixture ratio for acceleration must be effected by an accelerator pump. A sleeve 62 has a passage therethrough for idling fuel. The fuel ultimately reaches the passage 64 which supplies fuel to the idling fuel supply inlets (not shown) for delivering fuel adjacent the edge of the throttle valve.