Electro-pneumatic apparatus with a combined derivative-proportional action for controlling the fuel flow in a carburettor engine for motor vehicles

Claim 1

Electro-pneumatic apparatus for controlling the fuel flow in a carburettor engine for motor vehicles, comprising - an electrically-controlled cut-off device (3) for cutting off the fuel supply to the engine, - a control device (7) comprising a rigid casing (10) communicating with the induction manifold (5) of the engine, an electrical switch (17,18) having a movable control member (18) mounted in the casing (10), and a barometric absolute pressure sensor (13) disposed in the casing (10) and cooperating with the movable member (18) to energise and de-energise the cut-off device (3) through the switch (17,18) when predetermined pressure conditions exist in the induction manifold (5) and hence in the casing (10), characterised in that a differential pressure sensor (23) sensitive to variations in the pressure in the casing (10) is also mounted in the casing (10) and cooperates with the absolute pressure sensor (13) so that, upon variation of the pressure in the casing (10), the movement of the control member (18) of the switch . (17,18) is substantially equal to the sum of a first movement proportional to the pressure in the casing (10) and a second movement substantially proportional to the variation in the pressure in the casing (10).