Fuel injection pump unit with control and process for its calibration

In a fuel injection pump unit comprising a fuel injection pump, a displaceable control rod for adjusting the quantity of fuel injected per stroke of the pump, a position pickup for monitoring the position of the control rod, an actuator for displacing the control rod, a control unit which calculates a quantity of fuel to be injected M.sub.soll and from which a signal .beta..sub.soll which is representative of a desired position of the control rod is determined using stored characteristic values, a position controller for generating a control signal for the actuator for adjusting the control rod by comparing the desired control rod position signal .beta..sub.soll from the control unit with an actual position signal .beta. furnished by the position pickup, and adjustable stop means for limiting the displacement of the control rod wherein the stop means are adjustable to fixed distances k.sub.1, k.sub.2 from stop faces an the control rod, the distances k.sub.1, k.sub.2 are stored in the control unit and correspond to measured injection quantities M.sub.1, M.sub.2 wherein M.sub.1 is the idling injection quantity and M.sub.2 is the full load injection quantity and wherein at least one of the stop means is located so as to strike the corresponding stop face at a position corresponding to a value M* where M*<M.sub.1 or M*>M.sub.2 when a signal from the control unit overshoots a value corresponding to M.sub.1 or M.sub.2 but does not reach M.sup.*,

• a process for calibrating the fuel injection pump unit comprising the steps of:
• a) adjusting the stop means on a test-bench such that they have certain distances k.sub.1, k.sub.2 from their corresponding stop faces when the measured injection rates have certain values M.sub.1, M.sub.2 ;
• b) striking both stop means and the stop force and storing the corresponding pickup signals .beta..sub.0, .beta..sub.3 corresponding to the positions of the control rod in the control unit (2);
• and
• c) determining from the control unit pickup signals .beta..sub.1, .beta..sub.2 corresponding to the measured injection rates M.sub.1, M.sub.2 from the distances k.sub.1, k.sub.2 and the pickup signals .beta..sub.0, .beta..sub.3, from which pickup signals .beta..sub.1, .beta..sub.2 the positions .beta..sub.soll of the control rod corresponding to the desired injection rate M.sub.soll during operation are determined.