Valve for viscous fluid applicator

A valve for intermittently dispensing a viscous fluid, said valve comprising:

• a valve body defining a fluid chamber having a fluid outlet;
• a fluid inlet for communicating the fluid chamber with a source of the viscous fluid;
• a pole piece;
• an armature disposed within the fluid chamber for reciprocating movement between first and second positions, the armature having a first end located
• adjacent to the pole piece and a second end located adjacent to the fluid outlet, said armature having a stepped outer diameter including a first portion of a first diameter and a second portion of a reduced diameter, said armature preventing fluid flow through said fluid outlet when said armature is in one of said positions and said armature permitting fluid flow through said armature when said armature is moved away from said one position;
• and
• a solenoid coil for producing an electromagnetic field in a magnetic circuit including the valve body, the pole piece and the armature, for moving the armature from said first position to said second position,
• wherein at least a portion of the second diameter portion of the armature becomes magnetically saturated during a first portion of an operating cycle, causing magnetic flux of said electromagnetic field to be diverted from said portion of the second diameter portion of the armature through said first portion of the armature, and wherein flux paths are established over said first and second portions of the armature during a second portion of the operating cycle.

A valve for intermittently dispensing a viscous fluid, said valve comprising:

• a valve body defining a fluid chamber having a first end, a second end, and a fluid outlet near said second end;
• a fluid inlet for communicating the fluid chamber with a source of the viscous fluid;
• a pole piece having a pole face disposed at said first end of said valve body;
• an armature disposed within the fluid chamber for reciprocating movement between first and second positions, the armature including first and second ends, the first end of said armature having an armature face located adjacent to the pole piece, defining an interface between the pole face and the armature face, and the second end of the armature located adjacent to the fluid outlet;
• a sealing structure including an isolation sleeve for sealing the fluid chamber at said first end;
• and
• a solenoid coil for producing an electromagnetic field for moving the armature between first and second positions, the solenoid coil having first and second ends, wherein the interface between the pole face and the armature face is located adjacent to said first end of said solenoid coil.

A valve for intermittently dispensing a viscous fluid, said valve comprising:

• a valve body having a stepped axial bore, the valve body having a fluid inlet communicated with the axial bore and a fluid outlet;
• a pole piece at one end of the bore;
• an armature disposed within the axial bore for reciprocating movement between first and second positions, said armature having a stepped outer diameter including a first armature portion of a first diameter which is located near said pole piece and a second armature portion of a reduced diameter which is located between said pole piece and said fluid outlet;
• a solenoid coil for producing an electromagnetic field for moving said armature during an operating cycle;
• the second armature portion engaging an inner surface of the axial bore along a first bore portion thereof, and the first armature portion being maintained spaced apart from the inner surface of the axial bore along a second bore portion thereof, and wherein magnetic flux through said second armature portion is diverted to the first armature portion during an initial portion of the operating cycle.

A method for operating a valve intermittently for dispensing a viscous fluid, said method comprising:

• supplying the viscous fluid to a fluid chamber having a fluid outlet;
• positioning an armature within the fluid chamber for reciprocating movement between first and second positions to move an end of the armature into and out of engagement with the outlet;
• energizing a solenoid coil to produce an electromagnetic field for moving the armature from a first position to a second position during an operating cycle;
• causing a first portion of the armature to become saturated during at least a first portion of the operating cycle to divert magnetic flux of the electromagnetic field through a second nonsaturated portion of the armature during said portion of the operating cycle;
• allowing said first portion of the armature to become non-saturated during a second portion of the operating cycle.