Armature guide for an electromechanical fuel injector and method of assembly

• US 5,625,946 A
• Filed: 05/19/1995
• Issued: 05/06/1997
• Est. Priority Date: 05/19/1995
• Status: Expired due to Fees

• Current Assignee: Siemens Automotive Corporation (Siemens AG)
• Original Assignee: Siemens Automotive Corporation (Siemens AG)
• Inventors: Wieczorek, David P., Wildeson, Raymond, Weaver, L. Blair, Brinn, Benjamin F. Jr.
• Primary Examiner(s): WELDON, KEVIN P
• Application Number:
  US08/444,497
• Time in Patent Office: 718 Days
• Field of Search: 239/585.1-585.4, 239/900, 239/600, 251/129.01, 251/129.15, 251/129.21, 29/888.03, 29/888.41
• US Class Current: 29/888.41
• CPC Class Codes: F02M 51/0671 the armature having an elongated valve body attached thereto
• CPC Class Codes: F02M 61/12 characterised by the provision of guiding or centring means for valve bodies
• CPC Class Codes: F02M 61/168 Assembling; Disassembling; Manufacturing; Adjusting
• CPC Class Codes: Y10T 29/493 Valve guide making

Abstract

A low cost method for manufacturing and aligning the upper and lower guide members in a fuel injector reduces manufacturing cost and improves durability. The method teaches the use of an alignment tool to axially align both guide members before the guide members are rigidly secured to the valve body of the injector. The dimensional tolerances on the guide members are loose with the sole exception of the alignment aperture which is closely held.

Claims

1. A method for aligning the upper and lower armature guides in an electromechanical fuel injector wherein the armature has a tubular shaped end adjacent the stator means and an elongated valve stem extending from the tubular shaped end, said method comprising the steps of:

forming at least two bores in a valve body member, one bore axially extending the length of the valve body member and having a first diameter, a second bore having a second diameter extending from one end of the valve body to a point intermediate the ends and forming a shoulder at the intersection of the two bores;

inserting a lower armature guide member in said second bore, said lower guide member having an outer diameter smaller than the diameter of said second bore, the lower guide member having an axially concentric diameter forming a sliding fit with the valve stem;

inserting a valve seat member having a valve seat axially concentric with an axially extending through hole, a sealing means and an orifice member against the lower guide member forcing the lower guide member against the shoulder;

positioning an upper armature guide member on the end of the valve body member opposite the lower guide armature member, the upper guide member having an axially concentric diameter forming a sliding fit with the tubular shaped end of the armature;

axially aligning the concentric diameters of the lower and upper guide members with an aligning tool so that the armature reciprocally moves along the axis of the valve body member and the valve stem is centered on the valve seat member and closes the through hole;

securing the valve seat member, lower guide member, orifice member and orifice back up member to the valve body;

securing the upper guide member to the valve body member; and

then

removing the aligning tool.

2. A method for aligning the upper and lower guides of an armature means according to claim 1 wherein the step of securing the upper guide member is by means of laser welding.

3. A method for aligning the upper and lower guides of an armature means according to claim 1 wherein the step of securing the upper guide member is by means of magna forming.

4. A method for aligning the upper and lower guides of an armature means according to claim 1 wherein the step of securing the upper guide member is by means of crimping.

5. A method for aligning the upper and lower guides of an armature means according to claim 1 wherein the step of securing the valve seat member, lower guide member, and orifice member to the valve body is by means of crimping the end of the valve body member over the orifice back up member to locate the lower guide member against the shoulder in the valve body member.

6. An electromechanical fuel injector comprising:

a stator means;

an armature member co-axially aligned with said stator means, said armature member having a co-axial valve stem member;

an electromagnetic coil surrounding said stator means and operable to reciprocally move said armature member to and from said stator means;

a tubular valve body member having an axially extending bore and a knob means at one end, said valve body member integral with said stator means and including a valve seat member at the other end, said valve body member aligning said armature member for reciprocal movement of said valve stem member on and off said valve seat in response to said coil;

a lower guide member coupled to said valve seat member and axially aligned with said axially extending bore;

a substantially U-shaped upper guide member overlying said knob means on said valve body member and having an axially extending surface forming an elongated surface along said bore forming a sliding fit with said armature member, said upper and lower guide members operable to align said armature member and said valve stem member with said stator means and said valve seat member;

a housing member enclosing said coil member and said valve body member, said housing having a fuel inlet means for receiving fuel to be controllably discharged through said valve seat member when said valve stem member is moved off said valve seat member under control of said electromagnetic coil.

7. An electromechanical fuel injector according to claim 6 wherein said axially extending outer surface is formed to wrap around said knob means.