the embodiment according to the invention is realized , in the exemplary embodiment described below , in terms of a distributor injection pump of the kind schematically shown in fig1 . this is a distributor injection pump of the axial piston type , but the subject of the invention is also applicable to other fuel injection pumps , such as distributor injection pumps of the radial piston pump type , or individual pumps with only a single pump piston to supply a single cylinder of an internal combustion engine , or in - line pumps . nevertheless , the injection is especially advantageously realizable in a distributor injection pump , because then to supply the injection valves only a single electrically controlled valve is required , and the distribution to the individual injection valves is done with the aid of the distributor . in the distributor injection pump of the type shown in fig1 a pump piston 1 is provided , which is disposed displaceably and rotatably in a cylinder bore 2 and there on the face end encloses a pump work chamber 10 . the pump piston is coupled , for instance via a spring not otherwise shown , to a cam disk 6 , which has axially downward - pointing cams 5 embodied according to the invention . the cam disk is driven to rotate , in particular in synchronism with the rpm of the engine supplied by the injection pump , in a known way by a drive shaft not shown in further detail ; under the influence of the spring , the cam disk rolls along a known , axially stationary roller ring and consequently sets the rotating pump and distributor piston into a reciprocating feeding and aspirating motion . in its rotary motion in association with a pump supply stroke , in which fuel is positively displaced at high pressure out of the pump work chamber 10 , the pump piston comes to communicate with one of a plurality of injection lines 7 via a distributor groove 8 in the jacket face of the pump and distributor piston . the distributor groove communicates constantly with the pump work chamber via a longitudinal - conduit 9 . the injection line leads via a pressure valve 12 to a fuel injection valve 13 , which is assigned to the respective cylinder of an engine . the supply of fuel to the pump work chamber 10 is effected via an intake line 15 , which supplies fuel from a suction chamber 17 , which is essentially shown only in dashed lines and is enclosed inside the housing of the fuel injection pump . the suction chamber contains fuel from a fuel feed pump 18 , which is driven in synchronism with the fuel injection pump , for instance by the drive shaft , and thus pumps fuel in rpm - dependent quantities into the suction chamber . with the aid of an additional pressure control valve 19 , the pressure in the suction chamber is conventionally controlled as a function of rpm , if additional functions of the fuel injection pump are to be controlled with the aid of this pressure . via an overflow throttle 22 , fuel constantly flows back to the tank 23 , thereby making provision for cooling the injection pump or degassing the suction chamber . the intake line 15 leads into the pump work chamber via a check valve 16 , and the check valve opens in the direction of the pump work chamber . provided parallel to this check valve is an electrically controlled valve 24 , which controls a bypass line 21 around the pressure valve 16 and with the aid of which , upon opening of the valve , a communication is established between the pump work chamber 10 and the suction chamber 17 and the pump work chamber 10 is closed upon closure of the valve . the electrically controlled valve 24 , symbolically represented as a magnet valve , is controlled in a manner known per se in accordance with operating parameters by a control unit 25 . if the flow cross section of the valve 24 is sufficiently large , however , the check valve 16 may also be omitted . in that case , the pump work chamber is filled in the intake stroke solely by way of the electrically controlled valve . with the aid of this electrically controlled valve , the onset of high - pressure pumping of the pump piston is controlled in such a way that in the final analysis the injection onset is likewise controlled with the aid of this valve . upon closure , injection pressure builds up in the pump work chamber 10 and is delivered via the longitudinal conduit 9 and the distributor groove 8 to one of the injection lines 7 . when the electrically controlled valve reopens , the high - pressure pumping is interrupted , so that the closing time of the valve determines the instant of injection and the injection quantity . by means of this valve , a preinjection can now be realized as well without special triggering . according to the invention , the pumping sides of the cam flanks of the cams 5 are embodied such that , as shown in fig2 they generate a stroke course of the pump piston over time that is subdivided into a first range v , which begins with the supply stroke of the piston and ends after a short supply stroke ; a second range p , in which the piston is then set into a reverse motion , so that high - pressure pumping is thus effectively terminated and an interval between injections ensues ; and finally a third range h , in which the cam flank rises again and displaces the pump piston for the sake of further pumping of the main injection quantity . it can also be seen from the graph in fig2 how the electrically controlled valve , for instance a magnet valve or a piezoelectrically actuated valve , to control the onset of the preinjection quantity pumping and thus at the same time the onset of injection , is closed at point fb and is not opened again , to terminate the main injection , until point fe . the interruption of the injection is effected solely by the fact that no effective high - pressure pumping is possible through the cam range p . with this structurally dictated interval between injections , the duration of the interruption of the high - pressure injection can be done in principle with cam angles that are kept constant , and in particular that are independent of the switching speed of the electrically controlled valve and of the rpm . in individual cases it is also possible to modify the shape of the cam in view of the intended subdivided injection . instead of causing a reverse stroke motion of the piston , the piston can also merely remain in its position or be moved onward only slightly that its motion does not suffice to enable any significant injection , in such a way than an effective interval between injections ensues that reduces the overall fuel supply to the engine combustion chamber such that the pressure rise in the combustion chamber becomes less , thus making it possible to attain low - noise combustion . advantageously , the fuel injection pump of the type according to the invention supplies injection valves that are suitable to inject at a subdivided injection rate and that thus furnish a smaller injection cross section for the preinjection than for the main injection . such injection valves are known and need not be described further here . reference may be made for instance to german patent de 36 06 246 c2 . with the aid of injection valves embodied in this way , the requisite interval between the preinjection and the main injection can essentially be maintained even more exactly . the foregoing related to a preferred exemplary embodiment of the invention , it being understood that other variants and embodiments thereof are possible wihtin the spirit and scope of the invention , the latter being defined by the appended claims .