Abstract: A fuel injector including a flow balanced injector needle seal is provided. The fuel injector includes a needle in a fuel passage of the fuel injector body. The needle moves longitudinally in the fuel passage to selectively stop and start fuel injection from the fuel passage. The fuel injector includes a check valve assembly that maintains pressurized fuel in the fuel passage and permits fuel flow out of the fuel passage in response to a fuel injection event. The needle seal is provided between the check valve assembly and a sleeve that extends around the proximal end of the needle. The needle seal includes multiple inlet orifices for receiving a fuel flow into the needle seal that are positioned relative to one another so that net lateral forces on the needle are effectively offset from one another.

Abstract: A fuel injector including a flow balanced injector needle seal is provided. The fuel injector includes a needle in a fuel passage of the fuel injector body. The needle moves longitudinally in the fuel passage to selectively stop and start fuel injection from the fuel passage. The fuel injector includes a check valve assembly that maintains pressurized fuel in the fuel passage and permits fuel flow out of the fuel passage in response to a fuel injection event. The needle seal is provided between the check valve assembly and a sleeve that extends around the proximal end of the needle. The needle seal includes multiple inlet orifices for receiving a fuel flow into the needle seal that are positioned relative to one another so that net lateral forces on the needle are effectively offset from one another.

Abstract: A method for hard machining at least one orifice into a heat-treated fuel system component can include mounting the component into a holding fixture. The at least one orifice can include a first orifice. The method can include determining a desired orifice size of the at least one orifice based on a desired flow rate. The method can include hard machining the first orifice into the component. The method can include forming a first portion of the first orifice. The method can include forming, at an end of the first portion, a second portion of the first orifice. A diameter of the second portion can be smaller than a diameter of the first portion. The method can include forming a corner between the first portion and the second portion. The corner can have an edge condition having a dimension of 50 microns or less.