A self-adjusting breather bag for use in sealed storage structures to limit the contact of ambient atmosphere with the stored material. The self-adjusting of the lower part of the bag to a higher position in the structure is accomplished by strategically assembling elastic or resilient members inside or outside the bag which automatically raises the lower portion of the bag when the bag is in a substantially non-inflated condition. A retracting device may be used to store the elastic or resilient members to provide for a greater range of inflation and retraction of the bag.

BACKGROUND OF THE INVENTION 
An internal breather bag system has been used in conjunction with upright 
sealed storage structures such as that illustrated in U.S. Pat. No. 
3,568,588 to limit the contact between ambient atmosphere and stored 
material. To provide for high levels of storage, various systems of cord 
linkages have been used that allow the operator to pull the deflated bags 
toward the roof before the structure is filled with material. Access to 
the pull cords is not always convenient and neglecting to pull up the 
breather bag or bags often results in damage to the bags. These problems 
are eliminated by the system of the invention in assembling strategically 
placed elastic or resilient members with the breather bags which operate 
to automatically raise the lower portion of the bags during periods of 
non-inflation of the bags. 
SUMMARY OF THE INVENTION 
The invention is particularly directed to the attachment of elongated 
elastic strips or cords or like resilient members at each end to tabs or 
oar locks located inside the bag both at the upper and lower portions of 
the bag. The usual procedure is to attach two pair of the members at the 
upper end to a single tab and then extend them downwardly on both sides of 
the bag and spread them apart to form a cone-like appearance. They are 
then attached at the lower end to separate and laterally spaced members 
such as oar locks. The number of the resilient members employed throughout 
the length of each bag depends on the size of the bag and the height to 
which it is determined the bag should be raised. In some cases the 
resilient or elastic members may encircle the bag particularly if the bag 
is located externally of the structure to be protected. 
Under another embodiment of the invention the elastic or resilient members, 
usually cords or strips, may be secured in an elongated tube located 
inside the bag and extend therethrough and over pulleys at the ends of the 
tube and then are attached to various points in the top and bottom of the 
bag. The storing of the elastic or resilient member in the tube provides a 
greater length to these members to retract larger bags and always provides 
enough length to lift the bottom portions of the bag within the elastic 
limit of the elastic or resilient members. In some cases the resilient 
member may be springs stored in the tube to which ropes or cables are 
attached.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 
Referring to FIGS. 1-2 of the drawings there is shown a portion of a 
substantially airtight storage structure 1 such as a silo adapted to 
contain silage, haylage or other materials which require protection from 
spoilage by the ambient atmosphere. Structure 1 is normally supported on a 
concrete foundation, not shown, and includes a generally cylindrical shell 
2 and a roof 3. The silage or other stored material is removed from the 
storage structure by a bottom unloader, not shown, similar in structure 
and function to that described and shown in Tiedemann U.S. Pat. No. 
2,635,770. The unloading apparatus forms no part of the present invention. 
In order to balance the internal pressure and the external pressure within 
storage structure 1 so that air cannot reach the material stored therein, 
for purposes of illustration, a pair of breather bags 4 are located in the 
upper end portion of structure 1. Bags 4 are generally curved in length to 
conform to the curvature of the structure and each bag 4 in the 
illustration extends substantially half way around the interior of 
structure 1. Each bag 4 is connected at one end to a hose 5 extending 
through roof 3 to the outside of the structure and within a pipe 6 which 
is covered by a cap 7 in spaced relation to the pipe. With a decrease in 
pressure inside structure 1 air can flow through pipe 6 and hose 5 into 
the bags 4 and the bags will respond to a pressure increase or decrease 
inside structure 1 by contracting and discharging air through hose 5 and 
pipe 6 to thereby provide a constant equalization of internal and external 
pressure. 
In order to suspend each bag 4 inside structure 1 a yoke 8 is secured to 
the upper portion of each bag 4 and extends substantially the length of 
each bag. 
The upstanding portion of the yoke 8 is provided with a series of sliders 9 
which engage ribs 10 suspended from roof 3 and are able to slide along 
ribs 10. Roof 3 is formed of panels 11 and one edge of each roof panel 11 
provides the ribs 10 as a track or rail on which sliders 9 ride so that 
the bags can be removed by a cable, not shown, which encircles bag 4 
through the opening 12 in the top of the roof when the filler cover 13 is 
removed. The removal of the bags forms no part of the invention but it is 
necessary that the bags be supported in the upper end of structure 1 and 
the description presented illustrates one way in which the bags may be 
suspended. 
As bags 4 hang downwardly a substantial distance within structure 1, it is 
necessary that the bags be raised or elevated against roof 3 while the 
structure 1 is being filled. This has been accomplished previously by the 
use of manually operated cables attached to each bag as illustrated in 
Ebbinghaus U.S. Pat. No. 3,193,058. However, when the structure is closed, 
the cables necessarily are released which lowers the bag. Because of the 
funneling action, free flowing grains flow to the center of structure 1 
which can then draw a breather bag into the flowing grain and destroy it. 
The improved construction of the invention is shown in various forms in the 
drawings. Referring to FIGS. 1 and 3 of the drawing as particularly 
illustrated with respect to one of the bags 4 in FIGS. 1 and 3, bag 4 is 
provided internally with circumferentially spaced generally centrally 
located tabs or oar locks 14 at the upper end portion of the bag which are 
cemented or heat sealed or otherwise secured to bag 4. Additional oar 
locks 15 are secured to the inside of bag adjacent the lower end of bag 4 
located in general opposite to each other. 
As illustrated in FIGS. 1 and 3, an elastic or resilient cord or cable or 
any corresponding expansible and contracting means 16 is secured to oar 
lock 15 as shown in the left side of the drawing in FIGS. 1 and 3 and 
extends upwardly inside bag 4 and in engagement with oar lock 14 and 
thence downwardly on the opposite side of bag 4 and is secured at the 
lower end to a second oar lock 15. As illustrated in connection with the 
inflated breather bag 4 of FIG. 1 and the deflated breather bag 4 of FIG. 
3 corresponding cords or other expansible means 4 are provided throughout 
the extent of bag 4 and are connected to the upper oar locks 14 and lower 
oar locks 15 located inside of bag 4. 
Breather bags 4 may be of different materials of light weight but strong 
enough to confine the outside air inside bags 4. Polyvinyl chloride has 
proved to be one of the satisfactory materials for bags 4. 
The cords or strips 16 are of an elastomer material such as for example 
urethane, neoprene, EPDM polymers, silicone rubber, ethylene, propylene 
and the like which have the property of being able at room temperature to 
be stretched repeatedly at least twice their original length. Designing of 
the cords or strips 16 involves factors such as width, thickness, strength 
properties of the elastomer and the size of the bag to which it is to be 
applied. It is contemplated that any lightweight resilient material such 
as springs, for example, can be substituted for cords and strips of 
elastomer material or used in combination with non-elastic material. 
In some cases it is necessary that there be additional length in the cords 
or straps 16 than would be provided by the embodiment illustrated or 
described with respect to FIGS. 1-3. This is accomplished as illustrated 
in the second embodiment of the invention shown in FIGS. 4-11 and FIGS. 
14-16 by the use of a retracting device. 
FIG. 4 illustrates a bag 17 in an inflated condition and FIG. 5 shows the 
same bag in a deflated condition as bag 17 would appear inside of storage 
structure 1. Located inside the bag 17 is a tube 18 of plastic or the like 
which may be described as a retracting device or accumulator which takes 
up the elastic cord 19 anchored therein as at 20 and provides sufficient 
tension to lift breather bag 17 as internal pressure in storage structure 
1 approaches external pressure inside bag 17. 
FIGS. 4 and 8 illustrate three elastic cords 19 which are stored inside of 
tube 18 as at 20 and extend the length of tube 18, and thence through the 
channeled guide bracket 21 at a respective end of tube 18 and over a 
pulley 22. Pulleys 22 transfer the direction of elastic cords 19 from a 
radial to a longitudinal or vice versa direction of movement. Cords 19 may 
be secured to the tube at one end or both ends may be secured to the bag 
17. The pulleys 22 are distributed radially as may be observed in FIG. 5. 
The pulleys 22 rotate on shafts 23 extending through bracket 21 and 
secured thereto and the bracket 21 in turn is secured to tube 18 by the 
bolt 24. 
In view of the radial orientation of pulleys 22, one of the elastic cords 
19 extends through a guide channel of bracket 21 over a pulley 22 and 
thence upwardly inside bag 17 to the upper portion of bag 17 and is 
secured to the oar lock 25 in turn secured to bag 17. The other two cords 
19 extend downwardly from retracting device 18 in an opposite diagonal 
direction and are secured to oar locks 26 located and secured to the lower 
portion of bag 17. 
The bag 17 is suspended inside of the upper portion of structure 1 by a 
plurality of spaced grommets 27 and other members having no bearing on the 
present invention. Spaced grommets 27, four in number, are illustrated in 
FIGS. 4 and 5, although the number can be varied depending on the size of 
bag 17. 
FIGS. 9-11 illustrate a different location retracting system to show the 
versatility of location of the retraction device or tube 18. In the 
construction there shown the bag 28 is suspended in the upper portion of 
structure 1, not shown, by the grommets 29 which are shown as four in 
number which again may be varied in number. 
In this embodiment the tube 18 is located inside the upper portion of bag 
28 and extends longitudinally therein for a substantial distance. Tube 18 
at each end has secured thereto a channeled bracket 30 which is attached 
to the oar locks 31 by the bolt 32. Oar lock 31 in turn is secured to the 
inside of bag 28. 
A pair of elastic cords 33 are secured to the tube 18 at opposite ends and 
each cord 33 extends oppositely through tube 18 then through the channel 
of bracket 30 and over the pulley 34 which rotates on bolt 35 securing it 
to bracket 30 and downwardly where a first ring 26 is then secured to a 
second ring 37. A pair of rings 38 are secured to the intermediate ring 37 
and each supports a pair of elastic cords 39 which extend diagonally 
downwardly therefrom and each are secured to an oar lock 40 attached to 
the lower portion of bag 28. 
As is evident when the retracting device or system is employed it may be 
located in many different positions inside the breather bag and the 
elastic cords located therein may extend in various directions and may be 
connected to the bag by means other than the use of oar locks. More than 
one retracting device may be used inside each breather bag. 
It is also evident that other resilient members than cords could be 
employed. For example, a spring powered retractor might be employed with 
springs located inside the retractor tube with ropes or cables attached to 
the spring and to the bag. 
The location of the elastic cords or straps inside the breather bag is 
particularly important when the breather bag is used inside a storage 
structure 1 because with the cord or strap on the outside of the bag 
material during filling may become trapped between the elastic cord or 
strap and the bag body during the filling and be retained through numerous 
fill and empty cycles. 
However, in some cases it is desirable to have the bags located externally 
of storage structure 1 and in this case normally a straight bag is used 
rather than the curved type illustrated in the previous embodiments. 
Though not exposed to the possibility of having stored material 
accidentally placed on it, the external bag is commonly hung in a location 
where an increase in its hanging length upon deflection presents problems 
for traffic or storage area under the bag. Where an external bag is used 
although the internal resilient members may be employed, it may be found 
desirable to secure the resilient members to the outside of the bag. This 
type of construction is illustrated in FIGS. 12 and 13. 
In these figures there is shown a generally round, straight bag 41 in 
inflated condition in FIG. 12 and deflated condition in FIG. 13. The upper 
portion of the bag has an oar lock or the like 42 to which the cable 43 
suspends bag 41 from a beam in a barn or the like. Numerous oar locks 42 
and cables 43 would be employed throughout the length of bag to suspend 
the bag 41. The elastic or resilient strap or cord 44 completely encircles 
bag 41 and extends through oar locks 42 or the like which are 
intermittently secured to the outside of bag 41. 
The bag 41 is inflated by gases flowing through a conduit, not shown, but 
such as tube 20 in U.S. Pat. No. 3,510,319, which is connected to the 
upper part of a storage unit such as structure 1 and to bag 41, when the 
internal pressure inside the structure exceeds the atmosphere pressure and 
FIG. 12 illustrates this condition. In such condition the elastic members 
44 encircling bag 41 are in expanded condition. However, when the 
atmosphere pressure tends to exceed the pressure inside structure 1, the 
gases flow through the conduit, referred to above, from bag 41 and back 
into structure 1 thereby causing the elastic members 44 to collapse bag 41 
as illustrated in FIG. 13 because the atmosphere pressure exceeds the 
pressure inside bag 41. 
A spring powered retractor is illustrated in FIGS. 14-16 of the drawings. 
In these Figures there is shown a breather bag 45 which is suspended 
inside the upper portion of structure 1 such as by a plurality of spaced 
grommets 46 and other suspension members having no bearing on the present 
invention. 
Located inside of bag 45 is a tube 47 of plastic material or the like, as 
previously set forth with respect to FIGS. 4 and 5, which may be described 
as a retracting device or accumulator. A pair of pulleys 48 are secured 
respectively at opposite ends of tube 47, with each pair being disposed in 
radial orientation with each other. 
A spring 49 is stored inside of tube 47 and the non-elastic strips or cords 
50 illustrated in FIG. 16 as three in number are secured to opposite 
hooked ends 51 of spring 49. The respective cords 50 then extend out of 
each end of tube 47 and over pulleys 48 to change the direction of 
movement of cords 50 and are secured to the oar locks 52 in turn secured 
to the breather bag 45. 
As illustrated in FIG. 14, when bag 45 is in an inflated condition the 
spring 49 is in an extended position inside of accumulator or tube 47. As 
illustrated in FIG. 15, when bag 45 is in a deflated condition the tension 
of spring 49 raises the bag through cords 50 as spring 49 gradually moves 
to a contracted position as shown in FIG. 14. FIG. 16 illustrates the 
location of tube or accumulator 47 generally centrally of bag 45 but it 
could be offset from this position. 
The invention completely eliminates the use of cable or ropes to manually 
lift breather bags during filling and the use of elastic or resilient 
members to lift the bags overcomes the problem of human error by 
automatically raising the bottom portion of breather bags rather than 
having it done manually. 
Various modes of carrying out the invention are contemplated as being 
within the scope of the following claims particularly pointing out and 
distinctly claiming the subject matter which is regarded as the invention.