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Electrically-operated dispensing modules capable of dispensing small volumes of a viscous liquid at high operating frequencies and reproducibly among successive dispensed volumes of viscous liquid without the occurrence of stringing. The dispensing module may include a flux element having a portion

Electrically-operated dispensing modules capable of dispensing small volumes of a viscous liquid at high operating frequencies and reproducibly among successive dispensed volumes of viscous liquid without the occurrence of stringing. The dispensing module may include a flux element having a portion effective for interrupting circumferential electrical current paths. In another aspect, an end face of a pole piece of the dispensing module may include one or more non-magnetic spacer elements that prevent contact between the pole piece and armature when the dispensing module is opened.

대표청구항 ▼

What is claimed is: 1. An electrically-operated dispensing module for dispensing a viscous liquid, comprising: a module body having an outer housing and a liquid outlet; a pole piece in said module body; an armature disposed in said module body and movable relative to said pole piece between an o

What is claimed is: 1. An electrically-operated dispensing module for dispensing a viscous liquid, comprising: a module body having an outer housing and a liquid outlet; a pole piece in said module body; an armature disposed in said module body and movable relative to said pole piece between an opened position allowing liquid flow from said liquid outlet and a closed position preventing liquid fluid flow from said liquid outlet; an electromagnetic coil for selectively generating an electromagnetic field capable of moving said armature between said opened and closed positions; and a flux element positioned with a surrounding relationship about at least one of said electromagnetic coil, said armature and said pole piece, said flux element forming at least a portion of said outer housing of said module body, said flux element including a portion capable of interrupting circumferential electrical current paths in said flux element. 2. The electrically-operated dispensing module of claim 1 wherein said portion is a slot with a width effective to prevent circumferential electrical currents in said flux element. 3. The electrically-operated dispensing module of claim 2 wherein said flux element and said electromagnetic coil are aligned along a longitudinal axis, said flux element has an axial dimension, and said slot extends fully along said axial dimension of said flux element for defining a gap. 4. The electrically-operated dispensing module of claim 3 wherein said slot is substantially aligned with said longitudinal axis. 5. The electrically-operated dispensing module of claim 1 wherein said portion is formed from an electrically insulating material, said flux element and said electromagnetic coil are aligned along a longitudinal axis, said flux element has an axial dimension, and said electrically-insulating material extends along the entire axial dimension of said flux element. 6. The electrically-operated dispensing module of claim 1 wherein said module body has upper and lower body portions, said flux element positioned between said upper and lower body portions and having a rectangular cross-sectional profile. 7. The electrically-operated dispensing module of claim 1 wherein said armature includes a central flow passageway and a plurality of angled flow passageways coupling said central flow passageway in fluid communication with said liquid outlet. 8. The electrically-operated dispensing module of claim 1 wherein said module body has a lower body portion and an upper body portion with a liquid inlet receiving viscous liquid, said liquid outlet is defined in said lower body portion, said electromagnetic coil is positioned between said upper and lower body portions, said upper body portion includes a liquid inlet receiving viscous liquid, and said liquid inlet is coupled in fluid communication with said liquid outlet when said armature is in said opened position. 9. An electrically-operated dispensing module for dispensing a viscous liquid, comprising: a module body having a liquid outlet; a pole piece disposed in said module body and including a first end face; an armature disposed in said module body and including a second end face having a confronting relationship with said first end face of said pole piece, said armature movable relative to said pole piece between an opened position allowing liquid flow from said liquid outlet and a closed position preventing liquid flow from said liquid outlet; an electromagnetic coil operative for selectively generating an electromagnetic field capable of moving said armature between said opened and closed positions; and at least one spacer element projecting from said first end face of said pole piece, said at least one spacer element formed from a non-magnetic material selected from the group consisting of austenitic stainless steels and ceramics, said at least one spacer element being configured to maintain said first and second end faces with a non-contacting relationship when said armature is in said opened position. 10. The electrically-operated dispensing module of claim 9 wherein said at least one spacer element is a ring extending about said end face of said pole piece. 11. The electrically-operated dispensing module of claim 9 further comprising a plurality of spacer elements arranged about said end face of said pole piece. 12. The electrically-operated dispensing module of claim 9 wherein said module body has a lower body portion and an upper body portion with a liquid inlet receiving viscous liquid, said liquid outlet being defined in said lower body portion, said electromagnetic coil is positioned between said upper and lower body portions, and said liquid inlet coupled in fluid communication with said liquid outlet when said armature is in said opened position. 13. The electrically-operated dispensing module of claim 9 further comprising a flux element positioned with a surrounding relationship about at least one of said electromagnetic coil, said armature and said pole piece, said flux element including a portion capable of interrupting circumferential electrical current paths in said flux element. 14. An electrically-operated dispensing module for dispensing a viscous liquid, comprising: a module body having a liquid outlet; an electromagnetic coil operative for selectively generating an electromagnetic field, said electromagnetic coil including a plurality of solenoidal windings extending along a longitudinal axis between first and second axial positions, said first axial position being closer to said liquid outlet than said second axial position; a pole piece disposed in said module body and including a first end face; an armature disposed in said module body and capable of being moved relative to said pole piece by said electromagnetic field between an opened position allowing liquid flow from said liquid outlet and a closed position preventing liquid flow from said liquid outlet, said armature including a second end face confronting said first end face of said pole piece at a third axial position located between a midpoint of said first and second axial positions and said first axial position; and at least one spacer element projecting from said first end face of said pole piece, said at least one spacer element formed from a non-magnetic material and configured to maintain said first and second end faces in a non-contacting relationship when said armature is in said opened position. 15. The electrically-operated dispensing module of claim 14 wherein said third axial position is located approximately halfway between said midpoint and said first axial position. 16. The electrically-operated dispensing module of claim 14 wherein said module body has a lower body portion and an upper body portion with a liquid inlet receiving viscous liquid, said liquid outlet being defined in said lower body portion, said electromagnetic coil is positioned between said upper and lower body portions, and said liquid inlet is coupled in fluid communication with said liquid outlet when said armature is in said opened position. 17. The electrically-operated dispensing module of claim 16 wherein said pole piece includes a first flow passageway coupled in fluid communication with said liquid inlet and said armature includes a second flow passageway coupling said first flow passageway in fluid communication with said liquid outlet. 18. The electrically-operated dispensing module of claim 14 further comprising a flux element positioned with a surrounding relationship about at least one of said electromagnetic coil, said armature and said pole piece, said flux element including a portion capable of interrupting circumferential electrical current paths in said flux element. 19. An electrically-operated dispensing module for dispensing a viscous liquid, comprising: a module body having a lower body portion with a liquid outlet and an upper body portion; a pole piece disposed in said module body; an armature disposed in said module body and movable relative to said pole piece between an opened position allowing liquid flow from said liquid outlet and a closed position preventing liquid fluid flow from said liquid outlet; an electromagnetic coil operative for selectively generating an electromagnetic field capable of moving said armature between said opened and closed positions; a return spring biasing said armature axially away from said pole piece; and a nozzle removably attached to said lower body portion and having a hollow interior which contains a majority of said return spring. 20. The electrically-operated dispensing module of claim 19 wherein at least about 75% of said return spring is contained in said hollow interior of said nozzle. 21. The electrically-operated dispensing module of claim 19 wherein said armature includes a radially-extending flange positioned within said hollow interior and said module body includes a shoulder, said return spring being held between said flange and said shoulder. 22. The electrically-operated dispensing module of claim 19 further comprising a flux element positioned with a surrounding relationship about at least one of said electromagnetic coil, said armature and said pole piece, said flux element including a portion capable of interrupting circumferential electrical current paths in said flux element. 23. The electrically-operated dispensing module of claim 19 wherein said pole piece includes a first end face and said armature includes a second end face having a confronting relationship with said first end face of said pole piece; and further comprising: at least one spacer element projecting from said first end face of said pole piece, said at least one spacer element formed from a non-magnetic material, said at least one spacer element being configured to maintain said first and second end faces with a non-contacting relationship when said armature is in said opened position. 24. An electrically-operated dispensing module for dispensing a heated viscous liquid, comprising: a module body having a liquid outlet; a pole piece disposed in said module body; an armature disposed in said module body and movable relative to said pole piece between an opened position allowing liquid flow from said liquid outlet and a closed position preventing liquid fluid flow from said liquid outlet; an electromagnetic coil operative for selectively generating an electromagnetic field capable of moving said armature between said opened and closed positions; and an armature guide sleeve guiding said armature between said open and closed positions, said armature guide sleeve joined by a weldment with said module body, and said armature guide sleeve being formed from a first non-magnetic material and said module body being formed from a second non-magnetic material having a thermal conductivity greater than said first non-magnetic material. 25. The electrically-operated dispensing module of claim 24 wherein said first non-magnetic material has a thermal conductivity greater than about 20 W/(m쨌K) measured at room temperature. 26. The electrically-operated dispensing module of claim 24 wherein said first non-magnetic material is an austenitic stainless steel and said second non-magnetic material is a nickel-free copper alloy capable of being joined by said weldment with austenitic stainless steel. 27. The electrically-operated dispensing module of claim 24 wherein said module body includes a lower body portion containing said liquid outlet and an upper body portion separated from said lower body portion by said coil, said armature guide sleeve being joined to said lower body portion by said weldment. 28. An electrically-operated dispensing module for dispensing a viscous liquid, comprising: a module body having an outer housing, a lower body portion with a liquid outlet, and an upper body portion; an electromagnetic coil operative for selectively generating an electromagnetic field, said electromagnetic coil including a plurality of solenoidal windings extending along a longitudinal axis between first and second axial positions, said first axial position being closer to said liquid outlet than said second axial position; a pole piece disposed in said module body and including a first end face; an armature disposed in said module body and capable of being moved relative to said pole piece by said electromagnetic field between an opened position allowing liquid flow from said liquid outlet and a closed position preventing liquid fluid flow from said liquid outlet, said armature including a second end face confronting said first end face of said pale piece at a third axial position located between a midpoint of said first and second axial positions and said first axial position; at least one spacer element projecting from said first end face of said pole piece, said at least one spacer element formed from a non-magnetic material, said at least one spacer element being configured to maintain said first and second end faces with a non-contacting relationship when said armature is in said opened position; a flux element positioned with a surrounding relationship about at least one of said electromagnetic coil, said armature and said pole piece, said flux element forming at least a portion of said outer housing of said module body, said flux element including a portion capable of interrupting circumferential electrical current paths in said flux element; a return spring biasing said armature axially away from said pole piece; a nozzle removably attached to said lower body portion and having a hollow interior which contains a majority of said return spring; and an armature guide sleeve guiding said armature between said open and closed positions, said armature guide sleeve joined by a weldment with said module body, and said armature guide sleeve being formed from a first non-magnetic material and said module body being formed from a second non-magnetic material having a thermal conductivity greater than said first non-magnetic material. 29. A method of operating an electrically-operated dispensing module for dispensing a viscous liquid, the dispensing module having a module body with a liquid outlet, a pole piece, and an armature movable relative to the pole piece between an opened position allowing liquid flow from the liquid outlet and a closed position preventing liquid fluid flow from the liquid outlet, the method comprising: energizing an electromagnetic coil to generate an electromagnetic field for moving the armature relative to the pole piece from the closed position to the opened position; maintaining the armature and the pole piece in a non-contacting relationship while the electromagnetic coil is energized with a non-magnetic spacer element integral with the pole piece; directing the flux of the electromagnetic field to a flux element; and interrupting circumferential electrical current paths in the flux element while the electromagnetic coil is energized.