Fuel injection system for diesel motors

A fuel injection assembly, in each case for one cylinder of a diesel engine, consisting of a housing (1), of a controllable piston pump (5) and of an injection nozzle (4) adjoining the latter and having a nozzle chamber (25), the housing (1) possessing a fuel supply chamber (23) fed from outside and a return orifice (24) leading outward, the piston pump (5) possessing a pump piston bush (6) which is mounted longitudinally displaceably and is guided on a coaxial pin (20) fixed relative to the housing and which has at least one control orifice (17), and the pin (20) containing a first longitudinal bore (39) leading from the interior (18) of the pump piston bush (6) to the injection nozzle (4), wherein

• a) the pump piston bush (6) is sealingly surrounded by a sealing sleeve (50) which, with the outer wall of the pump piston bush (6), forms a closed sealing space (53), into which the control orifice (17) opens at the top and a first transverse bore (54) of the pump piston bush (6) opens at the bottom,
• b) the pin (20) possesses a second longitudinal bore (57) which is flow-connected, on the one hand, to the fuel supply chamber (23) and, on the other hand, via the first transverse bore (54), to the sealing space (53),
• c) the sealing space (53) is flow-connected to the return orifice via a second transverse bore (58) and a third longitudinal bore (59) in the pin (20).