Bung and stopper

A bung comprises a deformable member with a generally cylindrical middle portion generally coinciding with the bunghole when inserted, and upper and lower frusto-conical ends which increase in diameter as each end extends from the middle portion. The middle portion is preferably of a size less than the hole to facilitate insertion of bung into and removal from the bunghole. Where the hole is tapered, the middle portion is similarly tapered. The spool-like shape of the stopper helps to prevent unintentional disengagement of the bung from the hole and to prevent overinsertion of the bung into the hole. The bung may further comprise one or more pull tabs to facilitate removal. The bung may define a bore to allow gas pressure to escape from the container, thus acting as a stopper. A rigid annular insert at the opening of the throughbore prevents deformation of the circular shape of the opening.

FIELD OF THE INVENTION 
The present invention generally relates to a bung for sealing a container 
such as a wine barrel. The present invention also relates to a stopper 
which permits sealing of a container while also providing an opening for 
gas pressure to escape. 
BACKGROUND OF THE INVENTION 
For sealing a hole in a container such as a wine barrel, it is desirable to 
provide a bung which cannot be easily removed from the hole as a result of 
unintentional contact or as a result of increased pressures within the 
container, but which may be readily removed when it is desired to do so. 
The prior art has provided bungs where the surface contact area between 
the bung and the surface of the container defining the bunghole is 
relatively large. The arrangement of prior art bungs has typically 
resulted in a situation where a relatively small amount of force is 
required to disengage the bung from the hole, leading to accidental 
removal (e.g., knocking out) of the bung. Another disadvantage of such a 
prior art bungs is that conversely a relatively large amount of force is 
also required to insert and engage the bung with the hole, making 
insertion difficult. 
It may also be desirable to provide an opening through the bung which 
allows the release of gases from the barrel while also preventing 
contaminants from entering into the container. Such bungs with pressure 
release openings are often referred to as stoppers. The prior art has 
provided various combinations of stoppers and plugs for this purpose. 
However, prior art stoppers in such stopper-plug combinations have the same 
drawbacks as prior art bungs. Also, due to the shape of the barrel, 
stoppers made of materials such as rubber or silicone are irregularly 
distorted when inserted, resulting in the through-hole taking on an 
out-of-round shape. The out-of-roundness can prevent proper operation of 
the plug/valve used to prevent entry of contaminants. 
Accordingly, there remains a need in the art for a bung or stopper which 
reduces the possibility of unintentional removal from the bunghole, while 
requiring a relatively small amount of force to be intentionally inserted 
into and removed. There is a further need for means to eliminate 
out-of-roundness in the through-hole of deformable stoppers. 
SUMMARY OF THE INVENTION 
The present invention meets the foregoing needs by providing a bung with a 
middle portion which approximately coincides with the bunghole when 
inserted in the hole, and upper and lower portions which flare out from 
the middle portion. The cross-section of middle portion is of a size 
slightly less than that of the cross-section of the bunghole to minimize 
frictional surface contact area and thus facilitate insertion of the bung 
into and removal of bung from the bunghole. The flaring out of the lower 
portion helps to prevent unintentional disengagement of the bung from the 
bunghole due to pressures within the container or to accidental contact 
with the bung. The flaring out of the upper portion from the middle 
portion helps to prevent overinsertion of the bung into the hole. The bung 
may also provide one or more pull tabs to facilitate removal of the 
stopper from the hole. 
The bung of the present invention may be used as a stopper by providing a 
central throughbore to allow gases to escape from the barrel. To prevent 
deformation of the through-hole opening, a rigid annular insert is placed 
at the opening.

DETAILED DESCRIPTION OF THE INVENTION 
The structure and function of the preferred embodiments can best be 
understood by reference to the drawings. Where the same reference numerals 
appear in multiple figures, the numerals refer to the same or 
corresponding structure in those figures. 
As shown in FIG. 1, bung 10 of the present invention is made of a 
deformable and incompressible material, for example silicone rubber, and 
generally comprises upper portion 20, middle portion 22 and lower portion 
24. Bung 10 may be utilized as a stopper by providing central through-hole 
26 as shown in FIGS. 2-4. As shown in FIG. 4, bung/stopper 10 is inserted 
into bunghole B defined by a container wall W. 
At least a portion of the diameter of middle portion 22 is preferably 
slightly smaller than the diameter of the bunghole by, for example, 
approximately 0.050-0.001". The exact sizing determined by a person of 
ordinary skill based on permissible tolerances, actual wall thickness and 
hole diameter, among other factors. It is also preferred that no part of 
the middle portion be larger than the hole diameter. Having the diameter 
of middle portion 22 smaller than the diameter of the hole decreases the 
amount of contact surface area between bung/stopper 10 and the container 
wall defining the hole. Thus, the amount of force needed to insert 
bung/stopper 10 into the bunghole is thereby decreased. Where the bunghole 
B is tapered, middle portion 22 is preferably similarly shaped such that 
the amount of space between middle portion 22 and the edge of the bunghole 
is approximately uniform along the height of middle portion 22. For 
example, as is typical for wine fermentation barrels the bunghole B tapers 
such that diameter of hole is smallest at the interior of the barrel wall 
W. 
Upper and lower portions 20, 24 are two opposed and outwardly extending 
frusto-conical end portions of bung/stopper 10. As each of upper and lower 
portions 20, 24 extends from middle portion, each portion increases to a 
diameter greater than diameter of bunghole B. Thus, bung/stopper 10 is of 
a spool-like shape. Such an increase in diameter of upper portion 20 
facilitates in preventing overinsertion of stopper 10 into the bunghole. 
Similarly, such an increase in diameter of lower portion 24 facilitates in 
preventing unintentional disengagement of stopper 10 with bunghole B, for 
example, from accidental contact with stopper 10 or from increased gas 
pressure within the container as a result of a temperature increase and/or 
fermentation process. 
As shown in FIG. 4, the length of middle portion 22 is preferably less than 
the thickness of container wall W such that upper portion 20 and lower 
portion 24 partially reside within the bunghole. Thus, the corners of the 
hole deform parts of upper and lower portions 20, 24 in contact with the 
container wall. Alternatively, the bunghole is sealed by having only upper 
portion 20 or only lower portion 24 partially reside within hole 26. 
By way of example, a typical wine barrel bunghole has a wall thickness of 
approximately 0.900" and an outside diameter of approximately 1.980" 
tapering to an interior diameter of approximately 1.850". For use with the 
typical bunghole, middle portion 22 of bung 10 would preferably have a 
diameter of approximately 1.885" tapered to approximately 1.850" over a 
thickness of approximately 0.460". Each of upper and lower portions 20, 24 
would be preferably approximately 0.270" in thickness. The diameter of the 
outside end of the bung would be approximately 2.210" and the diameter of 
the inside end approximately 1.920" in this example. 
To facilitate removal of bung/stopper 10 from the bunghole, one or more 
pull tabs 28, preferably near an edge of top surface 30 of upper portion 
20, may be provided. Locating pull tab 28 near an edge of top surface 30 
facilitates deformation of upper and lower portions 20, 24 and thus 
facilitates removal of bung/stopper 10 from the hole. 
To allow gas pressure to escape from a barrel such as during fermentation 
of wine, stopper 10 may define a central bore 34. In order to prevent 
contaminants from entering into the barrel throughbore 34 a plug 40 is 
often used. 
As illustrated in FIG. 2, plug 40 includes a spherical portion 42 to 
facilitate creating a complete seal with the central bore 26 through the 
stopper. However, when stoppers are made of a deformable material, such as 
various forms of rubber, the shape of throughbore 26 may be deformed to a 
slightly non-circular shape due to a variety of reasons such as 
irregularities in the bunghole and the varying curvatures of a typical 
barrel. In particular, because a wine barrel is not a straight cylindrical 
shape, the wall of the barrel has a compound curvature. From side to side, 
the barrel is circular having a first radius, e.g. R as in FIG. 4. From 
top to bottom, the wall of the wine barrel is also bowed and has a second 
radius which is typically much larger than the first radius. The second 
radius would define a curvature perpendicular to the curvature of wall W 
shown in FIG. 4. Because of these compound curvatures, the bunghole in the 
wooden wine barrel can exert irregular forces on the bung plug or stopper. 
In the case of a stopper, the irregular forces may deform the throughbore. 
If the opening of throughbore 26 is not circular, then the plug, e.g. plug 
40, may not properly seal with the stopper. In order to void or lessen 
this problem, stopper 10 preferably may be provided with a relatively 
rigid insert 46, as shown in FIG. 4. Insert 46 is a ring of rigid material 
such as metal or rigid plastic that has an inner diameter which 
approximately matches the inner diameter of central throughbore 26. Insert 
46 is inserted into central throughbore 26 at the outer opening of the 
bore on the top of the stopper. In this manner, if irregular forces are 
exerted on stopper 10 in use, rigid insert 46 resists defamation of the 
opening of bore 26 so as to permit a good seal by a plug placed therein. 
The present invention has been described in terms of preferred embodiments. 
The invention, however, is not limited to the embodiment depicted and 
described. Rather, the scope of the invention is defined by the appended 
claims.