Solenoid actuator and fuel injector using same

• US 8,729,995 B2
• Filed: 12/20/2010
• Issued: 05/20/2014
• Est. Priority Date: 12/20/2010
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Venkataraghavan, Jayaraman, Bunni, Nadeem, Hanson, Christopher D., McDonnell, John
• Primary Examiner(s): BARRERA, RAMON M
• Application Number:
  US12/972,869
• Publication Number:
  US 20120153034A1
• Time in Patent Office: 1,247 Days
• Field of Search: 335/281, 251/129.16, 2395851-5855
• US Class Current: 335/281
• CPC Class Codes: F02M 47/027 Electrically actuated valves draining the chamber to release the closing pressure
• CPC Class Codes: F02M 51/061 using electromagnetic operating means
• CPC Class Codes: F02M 51/0625 characterised by arrangement of mobile armatures
• CPC Class Codes: F02M 51/0635 having a plate-shaped or undulated armature not entering the winding if entering the winding F02M51/0664
• CPC Class Codes: F02M 63/0015 electrical, e.g. using solenoid
• CPC Class Codes: F02M 63/0075 Stop members in valves, e.g. plates or disks limiting the movement of armature, valve or spring
• CPC Class Codes: H01F 7/1638 Armatures not entering the winding

Abstract

In one aspect, a fuel injector includes an injector body that defines a fuel inlet, a drain outlet and a nozzle outlet. A direct operated check valve is positioned in the injector body and includes a needle valve member with an opening hydraulic surface exposed to fluid pressure in a nozzle supply passage, and a closing hydraulic surface exposed to fluid pressure in a needle control chamber. The needle valve member is movable between a first position at which the nozzle supply passage is blocked to the nozzle outlet, and a second position at which the nozzle supply passage is open to the nozzle outlet. A needle control valve is positioned in the injector body and includes a control valve member movable between a first position at which the needle control chamber is fluidly connected to the drain outlet, and a second position at which the needle control chamber is fluidly blocked to the drain outlet. A solenoid actuator is positioned in the injector body and includes a stator assembly and an armature assembly coupled to the control valve member. One of the stator assembly and the armature assembly includes a non-magnetic insert that moves into and out of contact with another of the stator assembly and the armature assembly at an energized position and a de-energized position, respectively.

Claims

1. A solenoid comprising:

a stator assembly including;

a housing that includes a top piece defining a pin bore

a fragile highly magnetic core extending between a top end and an armature end;

a coil winding positioned around the fragile highly magnetic core;

a centerpiece extending completely through the fragile highly magnetic core with one end received in the pin bore, and an opposite end including a core shield covering the armature end of the fragile highly magnetic core;

the core shield including an armature stop; and

a flux ring;

an armature assembly including;

a pin movable between an energized position and a de-energized position;

an armature attached to move with the pin, and being movable within the flux ring, but being separated from the flux ring by a sliding air gap; and

one of the stator assembly and the armature assembly including a non-magnetic insert that moves into and out of contact with an other of the stator assembly and the armature assembly at the energized position and the de-energized position, respectively.

2. The solenoid of claim 1 wherein the fragile highly magnetic core is enclosed in a housing and the core shield.

3. The solenoid of claim 2 wherein the core shield is composed of a single material that is homogenous except for a central hardened layer that is the armature stop, has lower magnetic properties than a remaining portion of the core shield and occupies a minority of a volume of the core shield;

the non-magnetic insert is a portion of the armature assembly.

4. The solenoid of claim 2 wherein the non-magnetic insert is also non-metallic.

5. The solenoid of claim 2 wherein the core shield defines an insert cavity;

and

non-magnetic insert is mounted in the insert cavity.

6. The solenoid of claim 2 wherein the non-magnetic insert is a portion of the armature assembly.

7. The solenoid of claim 2 wherein the centerpiece includes the non-magnetic insert having the first end received in the pin bore of the top piece.