Fuel injector having residually stressed solenoid housing for improved pressure capapility

Patent metadata

Field	Value
Publication number	US-2020173408-A1
Application number	US-201816209058-A
Country	US
Kind code	A1
Filing date	Dec 4, 2018
Priority date	Dec 4, 2018
Publication date	Jun 4, 2020
Grant date	—

Abstract

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.

First claim

What is claimed is:

1 . A fuel injector comprising:
an injector body defining a longitudinal axis and having each of a fuel inlet and a low pressure outlet formed therein; a stack positioned at least partially within the injector body, the stack having each of a control chamber and a nozzle supply passage formed therein, and including a solenoid assembly and a tip piece having a plurality of nozzle outlets formed therein; an outlet check having a closing hydraulic surface exposed to the control chamber and adjustable between an open check position and a closed check position to open and close, respectively, the plurality of nozzle outlets; the solenoid assembly including a solenoid housing piece having a fuel bore formed therein that includes a segment of the nozzle supply passage; and the solenoid housing piece including a solenoid housing material in a base state, and a solenoid housing material in a residual compressive stressed state, and the fuel bore being formed by the solenoid housing material in the residual compressive stressed state.

2 . The fuel injector of claim 1 wherein the solenoid assembly further includes a coil-and-stator subassembly, and the solenoid housing piece further includes an outer housing surface, a first inner housing surface forming a central bore having the coil-and-stator subassembly positioned therein, and a second inner surface that forms the fuel bore at a location that is radially outward of the central bore.

3 . The fuel injector of claim 2 wherein the solenoid housing material in the base state is pervasive within the solenoid housing piece apart from the second inner surface.

4 . The fuel injector of claim 2 wherein the solenoid housing piece has a radial thickness through the fuel bore, and the fuel bore has a fuel bore diameter that is about 50% of the radial thickness or greater.

5 . The fuel injector of claim 2 wherein the stack further includes a fuel pressurization chamber formed therein that is fluidly connected with the nozzle supply passage.

6 . The fuel injector of claim 5 further comprising a plunger movable within the fuel pressurization chamber between an advanced position and a retracted position, and a tappet coupled with the plunger.

7 . The fuel injector of claim 2 further comprising a control valve assembly for the outlet check and including a valve member, a rod in contact with the valve member, and an armature coupled with the rod and movable between a first armature position and a second armature position to adjust the control valve assembly between an open valve position and a closed valve position, respectively, in response to energizing and deenergizing a solenoid of the coil-and-stator subassembly.

8 . The fuel injector of claim 7 wherein the stack further includes a valve housing piece formed of a valve housing material that is different from the solenoid housing material and positioned adjacent to the solenoid housing piece.

9 . A method of making a fuel injector comprising:
compressing solenoid housing material forming a fuel bore in a solenoid housing piece; inducing residual compressive stress in the solenoid housing material forming the fuel bore, in response to the compression of the solenoid housing material; installing the solenoid housing piece in a stack in a fuel injector; and orienting the solenoid housing piece in the stack such that the fuel bore forms a segment of a nozzle supply passage for feeding a pressurized fuel to a plurality of nozzle outlets in a tip piece of the fuel injector.

10 . The method of claim 9 further comprising installing a coil-and-stator subassembly in a central bore of the solenoid housing piece.

11 . The method of claim 10 wherein the orienting of the solenoid housing piece in the stack further includes fluidly connecting the fuel bore with a fuel pressurization chamber formed in the stack.

12 . The method of claim 10 wherein the compressing of the solenoid housing material further includes compressing solenoid housing material forming the fuel bore at a location that is radially outward of the central bore and with a bore diameter that is about 50% or greater of a radial thickness of the solenoid housing piece through the fuel bore.

13 . The method of claim 9 wherein the inducing of the residual compressive stress further includes inducing the residual compressive stress such that solenoid housing material forming the solenoid housing piece apart from the inner surface retains a base state.

14 . The method of claim 13 wherein the inducing of the residual compressive stress further includes ballizing the fuel bore.

15 . A fuel system comprising:
a plurality of fuel injectors each including a tip piece having a plurality of nozzle outlets formed therein; each of the plurality of fuel injectors further including a control valve assembly, and a solenoid assembly coupled with the control valve assembly; the solenoid assembly including a solenoid housing piece having a fuel bore formed therein for supplying a pressurized fuel to the corresponding plurality of nozzle outlets; and the solenoid housing piece including a solenoid housing material in a base state, and a solenoid housing material in a residual compressive stressed state, and the fuel bore being formed by the solenoid housing material in the residual compressive stressed state.

16 . The fuel system of claim 15 wherein each of the plurality of fuel injectors further includes a tappet and a plunger, and further comprising a camshaft structured to rotate in contact with each tappet.

17 . The fuel system of claim 16 wherein each of the plurality of fuel injectors further includes an outlet check, and a control valve assembly for the corresponding outlet check having a valve housing piece positioned adjacent to the corresponding solenoid housing piece and including a valve housing material that is different from the solenoid housing material.

18 . The fuel system of claim 17 wherein the solenoid housing material in the base state is pervasive within the solenoid housing apart from the solenoid housing material in the residual compressive stressed state.

19 . The fuel system of claim 17 wherein the solenoid housing piece has a radial thickness through the fuel bore, and the fuel bore has a fuel bore diameter that is about 50% of the radial thickness or greater.

20 . The fuel system of claim 17 wherein the control valve assembly includes a valve member, a rod in contact with the valve member, and an armature coupled with the rod and movable between a first armature position and a second armature position to adjust the control valve assembly between an open valve position and a closed valve position.

Assignees

• Caterpillar Inc

Inventors

• Kim Hoisan
• Yacoub Victor Iskander
• Thangaswamy Sridhar
• Brown Cory
• Smith Robert Joseph

Classifications

• F02M63/0015 Primary

  electrical, e.g. using solenoid · CPC title

• F02M57/023

  mechanical · CPC title

• F02M47/027 Primary

  Electrically actuated valves draining the chamber to release the closing pressure · CPC title

• F02M57/02

  Injectors structurally combined with fuel-injection pumps · CPC title

• F02M55/008

  Arrangement of fuel passages inside of injectors · CPC title