Fuel injection system for internal combustion engines with combined fuel pump control switch

Claim 1

Fuel injection system for an internal combustion engine (10) comprising a source of fuel (T); a fuel supply pump (15); electromagnetically operated fuel valve means (11) hydraulically connected to receive pressurized fuel from said fuel supply pump (15); electrical pulse generating means (TS, 22) connected to the injection vlave means (11) for controlling the operating time (Ti) thereof and hence, for controlling the amount of fuel injected during such opening time; and air quantity sensing means (LM) located in the induction pipe (25, 41) of the engine, connected to and providing an electrical control signal to said pulse generating means for controlling the pulse duration thereof in accordance with air flow through the induction pipe, said sensing means including a deflection member (30) located in the path of air flow through the induction pipe and means (46) acting on the deflection member for providing a reset force against deflection of the deflection member under air flow conditions, switch means (55, 56; 58, 59) and a switch operating means (57) connected to said flap or disk (30), said switch means being located with respect to said switch operating means to be opened when the flap or disk (30) is at rest position and to be closed when the deflection member (30) moves away from rest position, said switch means being connected to the fuel supply pump (15) for de-energizing the fuel supply pump when the engine does not require fuel, as sensed by absence of air flow in the induction pipe; and auxiliary force means (62) acting on the deflection member in a limited range of deflection from rest to open position and tending to decrease said reset force when the deflection member is at, or close to rest position, said auxiliary force means being operable for decreasing the reset force to permit movement of said deflection member away from rest position and hence reliable closing of the switch upon small air flow conditions in the induction pipe and for preventing the overriding of the deflection force of said small air flow by the reset force.