Exhaust gas recirculation valve

Abstract

An exhaust gas recirculation valve meters exhaust gas to the intake of an internal combustion engine. The valve includes an electromagnetic solenoid actuator having a magnetic circuit defined by a primary and a secondary pole piece. The pole pieces define an axial chamber in which is disposed an axially moveable armature and an associated valve member. The primary pole piece has a center pole member including a cylindrical inner wall which is open at a first end for receiving the armature. The armature and the cylindrical inner wall establish a fixed, radially extending primary air gap for flux passage while the outer wall extends in an outward taper from the first, open end of said center pole member and operates to increase the mass of the pole piece through which the magnetic circuit operates as the armature moves from the first, open end of the center pole member towards the second end. The secondary pole piece has a center pole member which includes a cylindrical inner wall, open at a first end for receiving the moveable armature and which is located in spaced opposing relationship to the first, open end of the primary pole to define a pole-to-pole gap therebetween. The armature and the cylindrical inner wall of the secondary pole define fixed, radially extending primary air gap for flux passage thereacross, and the outer wall extends in an outward taper from the first, open end. The outwardly tapering walls of primary and secondary poles operate to minimize the pole-to-pole gap through a minimization in opposing surface area therebetween allowing the length of the secondary pole and the surface area between secondary pole member and the armature to be maximized. The result is a minimization of the reluctance across said radial air gap and a maximization of the flux passage through the armature.