Fuel injector stroke calibration through dissolving shim
AssigneeGeneral Motors Corporation
InventorBrent J. Wahba
Life of this patent
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Abstract
An electromagnetic fuel injector and novel method for assembly and calibration having a solenoid assembly with a pole piece, a valve assembly including an armature, and a working air gap separating the valve assembly from the pole piece when the injector is in a de-energized state. A shim having a thickness equivalent to the length of the working air gap is placed between the pole piece and the valve member during construction of the injector. Following assembly, a solvent is introduced into the injector to dissolve the shim, which is constructed of a material readily dissolvable in the desired solvent, to define the working air gap and, therefore, the static flow through the injector.
Claims3
An electromagnetic fuel injector having a valve assembly moveable between open and closed positions with respect to a valve seat to establish fuel flow through said injector, a valve actuator comprising a solenoid assembly having a center pole piece with a working surface, and a shim disposed between said working surface and said valve assembly, and dissolvable by introduction of a solvent into said injector to define a working air gap between said valve assembly and said working surface.
An electromagnetic fuel injector, as defined in claim I, said shim constructed of a polymer material.
A method of calibrating an electromagnetic fuel injector comprising a valve assembly moveable between opened and closed positions with respect to a valve seat and an actuator comprising a solenoid assembly with a center pole piece having a working surface against which said valve assembly abuts in said opened position, said pole piece and said valve assembly separated by a working air gap when said valve assembly is in said closed position, comprising the steps of:
- locating a calibration shim having a thickness of said working air gap between said pole piece and said valve assembly during injector assembly;
- dissolving said calibration shim by introduction of a solvent into said injector to define said working air gap in said injector.
Dependencies are inferred from the claim text.