Fuel injection pump for internal combustion engines

Claim 1

A fuel injection pump for internal combustion engines having a reciprocably guided pump piston which thereby executes an intake stroke and a supply stroke and having a pump work chamber defined by said pump piston which upon the intake stroke of said pump piston can be made to communicate with a fuel suction chamber via at least one control opening disposed on a rotating part of said fuel injection pump driven in synchronism with the engine to be supplied with fuel and via a fuel supply conduit controlled by said control opening, and upon the supply stroke of said pump piston can be made to communicate in sequence, in the course of the rotation of said rotating part, with one at a time of a plurality of injection lines via a distributor groove disposed on said rotating part, further having a quantity adjusting device by means of which the effective supply stroke of said pump piston and thus the injected fuel injection quantity can be adjusted, wherein said quantity adjusting device is adjustable in its position by means of a regulator, wherein the improvement comprises a relief line leading from said pump chamber to said fuel suction chamber, said relief line being opened up directly by means of a valve closing member that is adjustable by the fuel pressure in said suction chamber counter to the force of a spring, the opening of said relief line being for the length of time during which a predetermined fuel pressure in said suction chamber is exceeded, and said valve closing member comprises a control piston, which is displaceable in a cylinder by the fuel pressure in said suction chamber counter to said spring and which on a jacket face thereof has a first control opening and, spaced axially apart therefrom, a second control opening, which both communicate continuously with said fuel suction chamber, and said relief line controlled by said first control opening discharges into said cylinder, while a second relief line discharges into said cylinder, said second relief line being opened up by said second control opening only beyond a minimum rpm and earlier than when said first relief line is opened up by said first control opening, wherein said second relief line is made to communicate alternatingly and in succession with said injection lines by means of a control groove on said rotating part, and that furthermore said fuel supply conduit is closable by means of an electrically actuatable valve.