A workpiece for a fuel injection component is made of a steel having compositions, by mass %, of C: 0.08 to 0.16%, Si: 0.10 to 0.30%, Mn: 1.00 to 2.00%, S: 0.005 to 0.030%, Cu: 0.01 to 0.30%, Ni: 0.40 to 1.50%, Cr: 0.50 to 1.50%, Mo: 0.30 to 0.70%, V: 0.10 to 0.40%, s-Al: 0.001 to 0.100%, and Fe and unavoidable impurities as remaining components. After heating the workpiece to a temperature of 950 C. or more and 1350 C. or less, the workpiece is subjected to a hot forging, and thereafter cooled at an average cooling rate of 0.1 C./sec. or more in a temperature range from 800 C. to 500 C., and at the average cooling rate of 0.02 C./sec. or more and 10 C./sec. or less in the subsequent temperature range from 500 C. to 300 C. to set an area ratio of a bainite structure after hot forging to 85% or more.

A pump unit for feeding fuel, in particular diesel fuel, to an internal-combustion engine; the pump unit comprising a head (2) inside which a cylinder (3) is formed along an axis; a pumping piston (4) housed inside the cylinder and comprising a head portion (24) inside the cylinder and an opposite foot portion (23) projecting outside the cylinder; wherein the piston is slidable inside the cylinder in a reciprocating manner between a first position and a second position where the foot projects from the cylinder by a greater or smaller amount respectively; and wherein the outer surface of the piston comprises a portion (16) with a surface finish so as to have less friction and a greater lubricant-retaining capacity than the remainder of the outer surface of the piston; the portion extending along the axis between the head of the piston and a first intermediate point (17) in the first position of the piston, the first intermediate point being inside the cylinder.

A fuel injector includes an injector body, and a stack within the injector body, and having a nozzle supply passage therein. The stack includes a solenoid assembly having a solenoid housing piece with a fuel bore formed therein that includes a segment of the nozzle supply passage. The solenoid housing piece includes a solenoid housing material in a base state, and a solenoid housing material in a residual compressive stressed state, with the fuel bore being formed by the solenoid housing material in the residual compressive stressed state. Residual stresses may be imparted by ballizing, nitriding, carburizing, autofrettage, or still another technique.

Methods of electroforming fuel injector nozzle structures such as, e.g., nozzle plates, valve guides, combinations of nozzle plates and valve guides, etc., as well as other articles incorporating microstructured features. The methods described herein can be used to electroform articles with high aspect ratio features in close proximity while reducing the likelihood of void formation during the electroforming process.

A method of fabricating a fuel injector nozzle comprising the steps of: (a) forming a first microstructured pattern in a first material; (b) replicating the first microstructured pattern in a second material to make a first mold comprising a second microstructured pattern in the second material; (c) replicating the second microstructured pattern in a third material to make a second mold comprising a third microstructured pattern comprising a plurality of microstructures in the third material; (d) replicating the third microstructured pattern in a metal material to make a replicated structure; and (e) removing the third material resulting in a nozzle having a plurality of through-holes through the metal material and corresponding to the plurality of microstructures in the third microstructured pattern. Each of the plurality of through-holes has a hole wall connecting a hole entry to a hole exit, and the hole wall of at least one through-hole has a side that curves from its hole entry to its hole exit.

A method is provided for achieving final air gap and parallelism of a control valve of a fuel injector, the control valve having a body defining an transverse top face and including a thick disc magnetic armature having a planar transverse upper face. The method includes a) measuring the actual position from the armature upper face and the body top face and, determining the actual parallelism error between said faces; and b) ablating the armature to generate an ablated upper face parallel to the body top face, the distance from the ablated upper face to the body top face being a final air gap.

A control valve assembly of a fuel injector includes a first valve arrangement wherein a first valve spool is guided in a first hydraulic bore provided in a body of the assembly. The control assembly further includes a first tubular sleeve having a seating portion which end face defines the first seating face, the first sleeve being fixed in the first hydraulic bore and the first spool extending through the sleeve.

Methods of making nozzles are disclosed. More specifically, methods of making nozzles that may be used as components of a fuel injection system are disclosed.

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.

A workpiece for a fuel injection component is made of a steel having compositions, by mass %, of C: 0.08 to 0.16%, Si: 0.10 to 0.30%, Mn: 1.00 to 2.00%, S: 0.005 to 0.030%, Cu: 0.01 to 0.30%, Ni: 0.40 to 1.50%, Cr: 0.50 to 1.50%, Mo: 0.30 to 0.70%, V: 0.10 to 0.40%, s-Al: 0.001 to 0.100%, and Fe and unavoidable impurities as remaining components. After heating the workpiece to a temperature of 950 C. or more and 1350 C. or less, the workpiece is subjected to a hot forging, and thereafter cooled at an average cooling rate of 0.1 C./sec. or more in a temperature range from 800 C. to 500 C., and at the average cooling rate of 0.02 C./sec. or more and 10 C./sec. or less in the subsequent temperature range from 500 C. to 300 C. to set an area ratio of a bainite structure after hot forging to 85% or more.