Pressure regulating valve

A pressure regulating valve, in particular for a fuel injection system comprising a valve housing having a slide bore defined therewithin and a regulating piston disposed in said slide bore, said regulating piston being displaceable to a variable extent in said slide bore as a function of pressure of a medium supplied thereto counter to force of a regulating spring, said regulating piston including a valve closing element arranged to cooperate with a first valve seat, said first valve seat being adapted to connect to fuel inlet lines of said fuel injection system, said valve closing element having a radially outwardly directed regulating face extending downstream thereof, the regulating face adapted to selectively access an outflow opening provided through the slide bore to communicate with a return fuel line upon a minimum displacement of the regulating piston being effected by pressure applied by the medium, said minimum displacement being travel of said regulating piston for a predetermined displacement path (s) in an axial direction away from the valve seat toward the outflow opening, said regulating piston further including a bypass conduit extending from the regulating face of said piston through a portion of said piston and terminating at a circumferential wall thereof in a relief opening, the relief opening being adapted to communicate with the outflow opening during that interval of path in which the piston has travelled a displacement path less than said predetermined displacement path (s).