GB1453095A - Carburettor cold enrichment device - Google Patents

Abstract

1453095 Spray carburetters FORD MOTOR CO Ltd 20 June 1974 [2 July 1973] 27314/74 Heading F1H A carburetter comprises a conduit conveying supplementary fuel and air for cold weather starting to a port in the induction passage downstream of the closed position of the throttle valve, temperature responsive means acting, when the temperature decreases below a predetermined level to progressively open a valve means controlling flow through the conduit, and vacuum servo means acting to move the valve means at times in a closing direction when the engine vacuum attains an engine running level, a lost-motion connection being provided between the servo means and the valve means. When a cold engine is being cranked, air is drawn from a point upstream of the throttle valve 24 via a port 74 and passage 72 to a port 64 where it joins fuel drawn from the float chamber 20 via a passage 76, port 66, passages 80, 100, 98 and a valve opening 110, the resultant rich mixture passing via a valve opening 112, a port 62, a passage 68 and a port 70 to a point downstream of the closed position of the throttle valve. When the engine has started, the increased engine vacuum acting on a diaphragm 140 overcomes the force of a spring 152 and pulls a spindle 144 to the right against a cam stop 184, thereby moving a valve spindle 132 correspondingly to the right to reduce the valve opening 110 and so reduce the fuel supply. At the same time, a valve orifice 182 is opened to admit air which has been heated by the engine exhaust manifold and has entered a thermostat chamber 116 via a conduit 134. The reduction of the fuel supply and the addition of the heated air both serve to reduce the mixture richness. As the engine heats . up, a bi-metallic spring 114 exposed to the heated air moves the valve spindle 132 further to the right to reduce the mixture richness still further. A lostmotion connection 148, 150 permits this movement of valve spindle 132 even when spindle 144 is arrested by the cam stop 184. However, any increase in ambient temperature acts via a bi-metallic spring 156 to raise cam plate 172 to permit further rightward movement of the spindle 144 under the influence of engine vacuum acting on diaphragm 140, whereby the increase in ambient temperature tends to cause rightward movement of the valve spindle 132. When the engine has reached normal temperature, the valve orifices 110, 112 are completely closed to cut off the supply of supplementary mixture.