27 toward a combustion chamber releasing an annular spray discharge orifice once fuel injector 1 opens a valve spring 30 abuts against a first spring system 31 of valve seat support 29 and via a second spring system 32 formed at valve needle head 28 exerts an initial stress on valve spring 30 in a closing direction which presses valve closure member 25 against valve sealing seat 27 via a fuel inflow bore 33 in valve body 2 the fuel may flow from a fuel inflow not shown to upper fuel chamber 16 a the fuel flows to lower fuel chamber 16 b and further to valve sealing seat 27 via openings 34 in valve body 2 and fuel bores 35 in coupler support 18 0025 fig2 shows a schematic section through fuel injector 1 configured according to the present invention in region ii of fig1 components already discussed in connection with fig1 have been provided with the same reference numerals the cut out section shows hydraulic coupler 23 with master piston 14 and slave piston 19 master piston 14 and slave piston 19 are inserted in a shared guide bore 17 of coupler support 18 coupler support 18 in turn is inserted in a bore 36 of valve body 2 and sealed by a ring 37 made of an elastomeric material via connecting bores 38 in coupler support 18 fuel.