Electromagnetic fuel injector

• US 4,384,681 A
• Filed: 07/30/1980
• Issued: 05/24/1983
• Est. Priority Date: 11/01/1978
• Status: Expired due to Term

• Current Assignee: Siemens-Bendix Automotive Electronics LP (Siemens AG)
• Original Assignee: The Bendix Corporation (Honeywell International Inc.)
• Inventors: Claxton, William B.
• Primary Examiner(s): Reeves, Robert B.
• Assistant Examiner(s): Church, Gene A.
• Application Number:
  US06/173,796
• Time in Patent Office: 1,028 Days
• Field of Search: 239/585, 239/533.2-533.12, 251/139-141, 251/337
• US Class Current: 239/585.5
• CPC Class Codes: F02M 2200/505 Adjusting spring tension by sliding spring seats
• CPC Class Codes: F02M 51/0678 all portions having fuel passages, e.g. flats, grooves, diameter reductions
• CPC Class Codes: F02M 51/08 specially for low-pressure fuel-injection

Abstract

A high flow rate electromagnetic injector valve with a rapid response time is disclosed for utilization in a single point fuel injection system. Centrally bored end caps are fixed at the front and rear ends of a tubular injector body and a coil wound on a bobbin is disposed inside the body chamber between the end caps. The front end cap receives within its bore a valve assembly including a valve housing and a needle valve with attached armature reciprocally movable against a valve seat to obturate a metering orifice in the valve housing. The valve housing contains fuel inlets for the pressurized entry of fuel into the injector and the needle valve is ported to provide fluid communication to the armature to relieve pressure build-up. The rear end cap mounts within its bore a core member acting as a stator which extends through a central bobbin bore to form a controllable air gap adjacent the armature. The core member further contains internally an adjustment screw and ball member. The ball member and adjustment screw cooperate with a recessed closure spring positioned substantially within the armature to controllably bias the needle valve against the valve seat. Because of its recessed position, the force of the closure spring is applied substantially along the central axis of the injector valve and the ball member prevents torsional windup forces from being generated by the spring,. O-ring seals for the bobbin bore are provided in compression between recesses in the bobbin and the slower contracting material of the front end cap and core member to produce extended cold temperature operation.

Claims

1. An electromagnetic fuel injector comprising:

a valve assembly for receiving pressurized fuel including a valve housing and a valve member having an armature portion, said valve member movable in said valve housing from a closed position to an open position in order to meter fuel from said valve housing;

an injector body in fluid communication with said valve assembly;

an electrically energizable stator means, contained within said injector body, for moving said valve member to one of said positions by magnetically attracting said armature portion;

means for moving said valve member to the other of said positions when said stator means is not energized;

said stator means including a coil wound on a bobbin wherein said bobbin has a different rate of thermal volume change than said injector body; and

means for sealing the pressurized fuel within the injector body including resilient means compressed in at least two places between a portion of said bobbin and a portion of said injector body such that the compression increases on said resilient means during temperature decreases.

2. An electromagnetic fuel injector as defined in claim 1 wherein:

said bobbin is elongated and includes a central bobbin bore with a recess at each end;

said resilient sealing means comprise a ring of an elastomeric material located in each of said recesses such that an outer surface of each recess is in contact with each elastomeric ring; and

said injector body portion includes an inner surface projecting into each bobbin recess such that the inner and outer surfaces coact to compress each elastomeric ring by contracting radially upon decreases in temperatures.

3. An electromagnetic fuel injector as defined in claim 2 wherein:

said injector body comprises a tubular body having a front and rear end cap fixed at either end; and

said stator means is located between said end caps in an inner chamber of the tubular body.

4. An electromagnetic fuel injector as defined in claim 3 wherein:

one of said inner surfaces is provided as an annular projection of said front end cap.

5. An electromagnetic fuel injector as defined in claim 4 wherein:

said other inner surface of said rear end cap is provided by a rod shaped core member inserted through a central bore in the rear end cap and which extends into said bobbin bore.

6. An electromagnetic fuel injector as defined in claim 2 wherein said bobbin has a greater rate of thermal volume change than said injector body.

7. An electromagnetic fuel injector as defined in claim 5 wherein said bobbin is comprised of Nylon.

8. An electromagnetic fuel injector as defined in claim 7 wherein said injector body portion is comprised of a low carbon steel.

9. An electromagnetic fuel injector as defined in claim 2 wherein said resilient rings are O-rings.

10. An electromagnetic fuel injector as defined in claim 2 wherein said inner and outer surfaces are cylindrical surfaces.

11. An electromagnetic fuel injector valve comprising:

a valve assembly including a valve housing, a needle valve reciprocal in a central bore of said valve housing, a valve seat and a metering orifice;

said needle valve obturating said metering orifice by its closure against said valve seat;

an armature attached to said needle valve adjacent a core member of an electrically actuatable stator means, said armature being attracted to said core member to open said valve when said stator means is actuated;

a spring member disposed between said core member and said armature in compression to apply a closure force against said needle valve to close said valve;

said core member includes means for adjusting the compression on said spring member including an adjustment screw threaded into a bore coaxial with said spring member such that turning said adjustment screw will cause axial movement along said bore and change the compression on said spring member; and

said adjusting means further including a member located between said adjustment screw and said spring member to alleviate any torsional force component from being applied to said spring member.

12. An electromagnetic fuel injector as defined in claim 11 wherein:

said valve assembly includes fuel inlet ports communicating fuel under pressure to said central bore of the valve housing;

said inlet ports located proximately to said metering orifice; and

said valve needle having at least one fuel passage communicating fuel from said central valve housing bore to said armature bore for relieving pressure build up in the space between said core member and said armature.

13. An electromagnetic fuel injector valve according to claim 11 wherein said member located between said adjustment screw and said spring member is a spherical ball member.