Proportional solenoid with armature motion sensing

A shielded solenoid for a solenoid operated valve, comprising:

• a solenoid body;
• an annular coil of electrical wire in said solenoid body, having a central hole therethrough;
• a first hollow magnetic pole piece oriented in said central hole adjacent a first axial end face of said annular coil and a second hollow magnetic pole piece coaxially oriented with respect to said first pole piece in said central hole adjacent a second axial end face of said annular coil remote from said first axial end face and being magnetically isolated from and immovably fixed with respect to said first pole piece, an end of said second hollow pole piece having a non-magnetic plug member closing an open end thereat;
• an armature of magnetic material rectilinearly movably displaceably mounted in said first and second hollow magnetic pole pieces, having a non-magnetic rod part projecting coaxially from at least one axially facing end thereof and being rectilinearly movable with said armature, said non-magnetic rod part having a magnet holder fastened thereto, said magnet holder having a permanent magnet fixedly oriented thereon;
• a hollow metallic shield member having a non-metallic plug closing one end thereof, said plug having a Hall effect sensor oriented therein to closely oppose said magnet on said magnet holder, said hollow metallic shield member covering a segment of an outer periphery of said second pole piece whereat said Hall effect sensor, said magnet holder and said permanent magnet are oriented, said shield member being configured to shield a Hall effect sensor from any significant electromagnetic field produced by said coil when effecting rectilinear movement of said armature so that movement of said armature and resulting corresponding movement of said magnet will cause said Hall effect sensor to produce a signal indicative of movement of said armature.