Solenoid flow control valve and frictionless plunger assembly

Claim 1

A valve for controlling fluid flow comprising: a valve body made of a magnetically-permeable material having a chamber defined therein, the valve body including a first flow port and a second flow port, both the first flow port and the second flow port fluidly communicating with the chamber; a seat member located on the valve body within the chamber, the seat member defining a mouth of the first flow port; a plunger provided within the chamber, the plunger being made of a magnetically-permeable material and positionable along a longitudinal axis extending through the mouth of the first flow port, such that the plunger is positionable between a first plunger position in sealing engagement with the seat member to prevent flow through the first flow port and a second plunger position spaced from the seat member to permit flow through the first flow port, wherein the plunger includes a first surface having an extension defined by a side wall and a sealing surface for sealing engagement with the seat member when the plunger is in the first plunger position, a second surface opposite the first surface, and a peripheral side surface extending between the first surface and the second surface, the plunger further having a through port extending therethrough from the second surface of the plunger to the side wall of the extension; means for supporting the plunger in alignment with the longitudinal axis as the plunger is moved between the first plunger position and the second plunger position, the supporting means connected to and radially extending from the plunger to the valve body; means for selectively positioning the plunger from the first plunger position to the second plunger position, the positioning means being independent of the supporting means and including a pole piece made of magnetically-permeable material affixed to the valve body within the chamber proximate to and spaced from the plunger, and a selectively,operable electromagnet having a magnetically-permeable core spool member located along the longitudinal axis adjacent the plunger, wherein selective operation of the selectively-operable electromagnet moves the plunger toward the core spool member to the second plunger position to form a magnetic circuit through the plunger, the pole piece, the valve body, and the core spool member, and further wherein the second flow port of the valve extends longitudinally through the core spool member and is axially aligned with the through port extending through the plunger for unobstructed flow through the second flow port when the plunger is in the second plunger position; and a spacer member of magnetically-nonpermeable material positioned between the plunger and the selectively-operable electromagnet to preclude direct contact therebetween as the plunger moves toward the core spool member.