Fuel injector with spiral-wound spring adjustment tube

A top-feed fuel injector for supplying fuel to an internal combustion engine comprising:

• an injector body having an inlet for admitting fuel into said injector, a nozzle for injecting fuel into the engine, and an internal passage extending from the inlet to the nozzle, wherein a first portion of the passage proximate to the nozzle is defined by a valve seat, and wherein a second portion of the passage is defined by an inner diameter of a generally cylindrical inlet tube;
• an electromagnetic coil on the injector body;
• a needle valve disposed within the passage proximate to the valve seat, the needle valve being moveable upon actuation of the electromagnetic coil between a closed position in which the needle valve sealing engages the valve seat, and an open position in which the needle valve separates from the valve seat to permit fuel to flow through the nozzle;
• an elongated spring adjustment tube disposed within the bore of the injector body opposite the valve seat, the spring adjustment tube including an end face opposing the valve seat;
• and
• a coil spring disposed within the passage between the needle valve and the end face of the spring adjustment tube, wherein the spring bears against the end face of the spring adjustment tube to resiliently bias the needle valve toward the valve seat,
• wherein the spring adjustment tube is formed from a rectangular section of a relatively-thin sheet stock that is rolled along a minor dimension to thereby obtain an elongated spiral-wound spring adjustment tube having at least about 1.5 turns when the spring adjustment tube is viewed in a transverse section, the spring adjustment tube having a nominal as-rolled outer diameter slightly greater than the inner diameter of the inlet tube and being resiliently radially collapsible to a collapsed outer diameter smaller than the nominal inner diameter of the bore in the injector body, whereby the spring adjustment tube resiliently presses against the bore in the injector body to thereby maintain the spring adjustment tube in a predetermined position within the inlet tube in the injector body relative to the valve seat.