IC engine butterfly valve carburettor - has piston responsive to air pressure holding valve open during deceleration

摘要

The butterfly wave (2) is mounted on a spindle (3) which carries the operating lever (4) and a second lever (8) which is free to rotate relative to the spindle. The lever (4) has an adjusting screw (7) which abuts against the stop (9) on the lever (8). Under engine cruising conditions, the stop (9) is held clear of the screw (7) by the action of a piston device (12). The latter receives pressure from a vacuum tapping (23) immediately upstream of the butterfly and from a tapping (38) has a valve (44) adjusted in response to the depression in the inlet pipe (1) and opened when this depression is greater than that corresponding to engine deceleration. Thus the piston device moves the stop to hold the butterfly open to increase airflow.