Dispensing – Motor operated outlet element
Reexamination Certificate
2000-02-11
2001-10-23
Shaver, Kevin (Department: 3754)
Dispensing
Motor operated outlet element
C251S129070, C251S129150, C251S129180, C335S227000, C335S279000
Reexamination Certificate
active
06305583
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates generally to a valve for viscous fluid applicators.
Many packaging applications require the application of adhesive to flaps for sealing packages. In some cases in which a liquid adhesive or glue is used, valves are used to dispense the glue for application to the packages being sealed.
One dispenser for use in dispensing viscous fluids, such as hot melt adhesives, is disclosed in U.S. Pat. No. 5,875,922. The dispenser includes an armature mounted within a fluid chamber for reciprocating motion relative to a pole member. The armature is adapted to permit the hot melt adhesive to flow through and around the armature as the armature is moved towards the pole member.
However, the interface between the armature and the pole piece is located near the center of the solenoid coil. Consequently, the fluid chamber extends within the interior of the solenoid, and a portion of the armature extends half the length of the solenoid coil. The additional length required for the armature, results in increased mass for the armature. Moreover, fluid flow paths through and around the armature are lengthened. Moreover, sealing between the fluid chamber and the solenoid coil must be provided around coextensive portions of the solenoid coil and the armature.
Thus, the dispenser includes an elongated tube which is interposed between the armature and the dispenser body to provide sealing for the fluid chamber. The sealing tube is made of a heat resistant, non-magnetic material, such as stainless steel. The sealing tube produces a long air gap between the armature and the valve body, with the sealing tube located in the air gap substantially the entire length of the armature. Consequently, the magnetic force used to drive the armature must be large enough to compensate for the losses due to the presence of non-magnetic sleeve in the air gap.
A further consideration is that viscous fluid dispensers of this type preferably must be adapted to permit adjustment in the stroke of the armature due to allow some leeway in manufacturing tolerances. In the dispenser disclosed in the '922 Patent referenced above, the gap between the armature and the pole piece is adjusted by turning the pole piece which is threaded into the body.
SUMMARY OF THE INVENTION
The disadvantages and limitations of the background art discussed above are overcome by the present invention. With this invention, there is provided a valve for intermittently dispensing a viscous fluid. The valve includes a valve body defining a fluid chamber having a fluid outlet and a fluid inlet for communicating the fluid chamber with a source of the viscous fluid. The valve includes a pole piece which closes the fluid chamber at one end, and an armature disposed within the fluid chamber for reciprocating movement between first and second positions. The armature prevents fluid flow through the fluid outlet when the armature is in one of the positions, and the armature permits fluid flow through the fluid outlet when the armature is moved away from that position. The valve further includes a solenoid coil for producing an electromagnetic field in a magnetic circuit which includes the valve body, the pole piece and the armature, for moving the armature from the first position to the second position. The armature cooperates with the valve body to define at least first and second air gaps and is configured and arranged to cause at least a portion of the magnetic flux to be diverted from one of the air gaps to the other gap during at least a portion of each operating cycle.
A first large diameter portion of the armature is spaced apart from an inner surface of the axial bore along a first portion thereof, and a second portion of the armature engages a further inner surface of the axial bore along a second portion thereof. The second portion of the armature supports the armature for axial movement within the axial bore. At least a portion of the magnetic flux through the second portion of the armature is diverted through the first portion of the armature during an initial portion of each operating cycle.
In one embodiment, magnetic flux passing through the first air gap produces a magnetic force for moving the armature from the first position to the second position. Magnetic flux passing through the second air gap provides a holding force for maintaining the armature at the second position. The first and second air gaps are located along the axial extent of the armature. The first air gap provides a reluctance that is greater than the reluctance provided by the second air gap.
In accordance with a further aspect of the invention, the valve includes a sealing structure for sealing one end of the fluid chamber. The sealing structure includes an isolation sleeve having an axially extending portion and a radially extending portion. The axially extending portion is interposed between the solenoid coil and one end of the pole piece. The radially extending portion is interposed between an inner surface of the body and the first end of the armature.
Further in accordance with the invention, the nozzle is adjustably mounted in the fluid outlet for allowing adjustment of the stroke of the armature, independent of manufacturing tolerances.
REFERENCES:
patent: 4488665 (1984-12-01), Cocks et al.
patent: 5110087 (1992-05-01), Studtmann et al.
patent: 5156341 (1992-10-01), Terakado et al.
patent: 5392995 (1995-02-01), Wahba
patent: 5647387 (1997-07-01), Tsutsui
patent: 5749527 (1998-05-01), Fujikawa et al.
patent: 5769328 (1998-06-01), Zdyb et al.
patent: 5875922 (1999-03-01), Chastine et al.
patent: 5915591 (1999-06-01), Erickson et al.
patent: 5934520 (1999-08-01), Byerly et al.
Stobbs Thomas J.
Ward James R.
Keasel Eric
Reinhard, Boerner, Van Deuren, Norris & Rieselbach, s.c.
Shaver Kevin
TLX Technologies
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