Air valve for a fillable poly bag

An air valve for a poly bag that permits the escape of air from the bag as it is filled by a filling tube. The air valve consists of a plurality of slitted openings in one top corner of the bag and a valve flap mounted in the poly bag near the slitted openings that closes and seals the openings as filling material engages and moves the flap.

BACKGROUND OF THE INVENTION

Side gusseted paper bags have been commercially made for many years with openings that permit bag charging or filling. But these bags are quite costly, not only because of the additional materials needed about the bag filling opening, but also because of the labor and time to close and seal the bag.

One of the problems with fillable bags is the entrapment of air during the filling process which promotes poor filling and other problems.

The following patents were found in a preliminary patentability search:

UNITED STATES PATENT APPLICATION PUBLICATION

FOREIGN PATENTS

The Harvey, U.S. Pat. No. 3,276,670, shows a tapered side gusseted bag but has no filling valve. The Piazze, U.S. Pat. No. 3,618,478, shows a gusseted bottom bag with diagonal heat seals but has no filling valve either.

The Benoit, U.S. Pat. Nos. 4,571,235 and 4,816,104, show a T-shirt bag with diagonal heat seals at the bottom. Again, it has no filling valve. The Benoit, U.S. Pat. No. 4,655,737, is duplicative with respect to the Benoit '235 patent.

The Roen, et al., U.S. Pat. No. 4,717,262, shows a gusseted bottom bag with diagonal heat seals and a sine wave handle. The Humphrey, U.S. Pat. No. 4,764,030, shows serrated bags on a roll but no discharge or filling valve.

The Olesen, U.S. Pat. No. 4,881,825, discusses both a filling valve and a discharge valve and a “block” style bottom and top, formed by folding and overlapping the ends of an open tube onto itself much like gift wrapping a box but tucking the sides inwardly and then folding the paper onto itself. SeeFIG. 10, for example. The discharge valve is for the purpose of pouring product out of the bag and no details are shown of the charging features in Olesen's bag.

The Beer, U.S. Pat. No. 4,913,561, shows what appears to be a valve on the upper left corner of the bag but rather than that, it is a heat seal which is intended to allow the bag to square once it is filled with product.

The Gelbard, U.S. Pat. No. 4,943,167, shows a side gusseted T-shirt bag made three across at one time and involves the continuous slitting and heat sealing of one tube longitudinally into three longitudinal tubes, post gusseting and heat sealing to create a top and bottom of the bag.

The Mundus, U.S. Pat. No. 4,959,114, shows a method which includes feeding flat sheet roll stock, folding it over into two, post gusseting it and sealing it into gusseted tubing with a longitudinal heat seal and then trimming off the excess.

It is a primary object of the present invention to ameliorate the problems noted above in prior art chargeable bags.

SUMMARY OF THE PRESENT INVENTION

In accordance with the present invention, an air valve for a polybag is provided that permits the escape of air from the bag as it is filled by a filling tube. The air valve consists of a plurality of slitted openings in one top corner of the bag and a valve flap mounted in the polybag near the slitted openings that closes and seals the openings as filling material engages and moves the flap.

The valve flap is generally rectangular and constructed of a material similar to the polybag itself. It may be heat sealed behind one of the panels of the polybag adjacent the corner of the bag where the filling tube is inserted. This location is selected because it is the area of bag that is last to fill. The bag fills diagonally toward that corner because of the filling tube orientation.

The openings in the polybag itself are crossed slits to achieve better sealing by the flap valve, while the holes in the flap valve are circular to promote air flow.

In some cases the holes in the flap valve may be eliminated because, depending upon bag construction, air may flow around the flap valve out the polybag slitted openings. The holes in the flap valve prevent the premature closing of the polybag air openings.

Other objects and advantages will appear more clearly from the following detailed description.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present air valve can be incorporated in a variety of different types of poly bags including the square top and square bottom poly bag illustrated inFIGS. 1 to 9, the side gusseted poly bag illustrated inFIGS. 10,11, and12and open bottom bags(not illustrated).

Referring to the drawings and particularlyFIGS. 1 and 2, the square bottom bag10is illustrated including a front panel11, side panels12and13, rear panel15(seeFIG. 3), a top16formed by inwardly folding upper side panel portions18and19over which are folded front wall portion21and rear wall portion22. The heat sealing lines are designated at25,26, and27. A tubular panel29is fixed to side panel portions18by heat sealing at30(see alsoFIG. 3) and forms part of the filling tube chute. The upper bight portion32of sheet21, is heat sealed by25,26,27to the front wall panel21and rear wall panel22.

The heat seal at25and26does not attach the side wall portion21to the top panels21and22so that feeding tube34may be inserted between panel portions21and22and side panel portions18to fill the bag. At the right top portion of the bag, however, heat sealing portion27does seal top panels21and22to the side panel portion19so that the right top portion of the bag is always sealed.

InFIGS. 5 and 6, the square bottom40of the bag is illustrated with appropriate heat sealing lines41.

As seen inFIGS. 1 to 4, an air escape valve40is illustrated including four cross-slitted openings41in side panel portion18and a flap valve43having a plurality of round holes45therein that are offset inwardly relative to the bag with respect to the cross slit openings41to achieve the desired sealing of the cross slit openings41as the flap valve moves upwardly as seen inFIG. 3, closing off the openings41.

The flap valve43is generally rectangular and is heat sealed at46to the underside of the side panel portions18, as seen in exploded fashion inFIG. 4.

As seen inFIGS. 7,8, and9, as material is discharged into the bag from the feeding tube34, material in the bag fills the bag diagonally as seen at48inFIGS. 6 and 49inFIG. 7relative to the corner of the bag at which the air valve40is located. This permits the valve40to remain open to permit air to escape until the bag is almost completely filled and is an important aspect of the present invention.

As seen inFIG. 9, when the bag becomes almost completely filled, the valve40seals the opening41and as the feeding tube34is withdrawn from the chute21, material collapses the heating chute against the top wall portions21and22.

As mentioned above, as the bag fills, air exits the bag through holes43and slitted opening41. Air flowing through the holes43maintains the flap45in an opened position and prevents inadvertent closure. In some cases this is not a problem, and in those cases it may be possible to eliminate the holes43. It should be understood that the material itself and not air impinging on the lower surface of the flap45closes the valve to the position illustrated inFIG. 9.

A gusseted poly bag110is illustrated inFIGS. 10,11, and12, incorporating the present air valve140that operates in substantially the same manner as the valve40inFIGS. 1 to 9embodiment. In the gusseted poly bag140, the inward extension121of the upper portion of side gusset112defines the chute121ashown inFIG. 11, and a separate panel21is unnecessary as shown inFIGS. 1 to 9. Flap valve143is heat sealed at146to the outward part of folded in gusset portion121. Cross slits141are formed in the upper reaches of the side gusset112slightly beneath the fold line165. As in theFIGS. 1 to 9embodiments, the holes145in the flap valve143are offset from the cross slitted openings141. Valve140operates in the same fashion as in theFIGS. 1 to 9embodiments but the location of the valve is slightly different.