Dispensing – Motor operated outlet element
Reexamination Certificate
2000-01-14
2001-07-03
Shaver, Kevin (Department: 3754)
Dispensing
Motor operated outlet element
C222S518000, C222S571000, C222S509000, C251S335300, C239S585100
Reexamination Certificate
active
06253972
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention concerns liquid dispensing valves, and in particular a valve for dispensing liquid glue accurately and at high repetition rate.
Liquid dispensing valves with reciprocal valve pins operating against an orifice with a valve closure seat are well known. Typically such valves are retracted by a solenoid and urged toward closure by a spring. See, as examples, U.S. Pat. Nos. 5,875,922, 5,405,050, and 4,962,871. See also copending application Ser. No. 09/075,776, filed May 11, 1998, now U.S. Pat. No. 6,032,832, which shows a pressure-balanced glue dispensing valve requiring only a very small spring pressure for valve closure.
It is among of the objects of this invention to simplify the design and structure of a liquid dispensing valve while making the valve structure more rugged, reliable and long-lasting, particularly in a high repetition rate glue head for applying glue to paper or other materials in a production line. This is accomplished through use of a novel device that isolates glue or other liquid from leakage up the shank of a valve pin while also applying the requisite spring force to maintain the valve closed under a range of specified pressure conditions.
SUMMARY OF THE INVENTION
In the disclosed invention a liquid valve particularly suited for dispensing of glue at high repetition rate has a solenoid-retracted pin that normally engages a valve seat to close the valve. Glue under pressure enters the chamber in which the pin operates, close to the valve seat. To seal against the flow of pressurized glue up along the pin toward the solenoid, and also to exert a light valve closing force on the pin, a thin metal corrugated bellows member is sealed and fixed to the pin near the valve closing end of the pin, at one end of the bellows, and sealed and fixed to a housing element or fitting within which the pin slides, at an opposite, upper end of the bellows. The geometry of the valve seat and the valve closure end of the pin is such that only a very slight retraction of the valve pin opens the valve sufficiently to deliver glue at full flow velocity through the valve's orifice. The valve is capable of accurate glue dispensing through a wide range of operating pressure.
In a preferred implementation of the invention, a valve for dispensing liquid under pressure, and specifically, liquid glue under pressure in one embodiment includes a valve housing with a valve pin positioned in the housing for axial reciprocation. The pin has a valve closure end and an opposite end. At a downstream end of the valve housing is a valve orifice surrounded by a valve seat positioned essentially coaxial with the valve pin, for closure of the valve when the pin is engaged against the seat. The housing defines a liquid chamber upstream of the orifice and surrounding the valve pin near its valve closure end.
A bore to receive the pin in sliding engagement is provided in the housing, preferably via a pin slide fitting secured to the housing by threaded engagement, this fitting defining an end of the liquid chamber. The valve pin passes through the opening in the slide fitting for reciprocating sliding movement relative to the fitting.
An electromagnetic retraction device such as a solenoid is connected via its movable solenoid pin or plunger to the valve pin for axially retracting the pin away from the valve seat and opening the valve when power is applied to the retraction device. A liquid supply channel leads into the liquid chamber preferably from an oblique angle, and has an upstream end with means for connection to a supply of pressurized liquid, e.g. liquid glue.
An important feature of the invention is the bellows member, having an elongated shape with corrugations transverse to the length of the valve pin. This bellows member surrounds the valve pin and seals the liquid chamber from leakage along the valve pin as well as isolating most of the valve pin from the liquid. The bellows serves the additional important purpose of exerting a spring force on the valve pin sufficient to retain the valve pin in closed position against the seat under a preselected range of liquid pressure conditions.
In one preferred embodiment the bellows member exerts about 14.4 ounces of closure force on the valve pin, with the valve pin having a diameter of about {fraction (3/64)} inch and the bellows having an outside diameter of about 0.11 inch.
REFERENCES:
patent: 3132775 (1964-05-01), Trumbull et al.
patent: 4579255 (1986-04-01), Frates et al.
patent: 4962871 (1990-10-01), Reeves
patent: 4976403 (1990-12-01), Bramblet
patent: 5405050 (1995-04-01), Walsh
patent: 5794825 (1998-08-01), Gordon et al.
patent: 5875922 (1999-03-01), Chastine et al.
patent: 6032832 (2000-03-01), Dority et al.
DeVito Thomas P.
McArdle John
Freiburger Thomas M.
Golden Gate Microsystems, Inc.
Nicolas Frederick C
Shaver Kevin
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