Environmentally controlled storage containers

A breathing type storage housing is exposed night and day to fluxuating outdoor air temperature. The housing defines a substantially sealed container of air that is alternately warmed and cooled by heat transferred through the housing due to daytime solar warming and nighttime cooling of the housing. Pressure responsive valves connect the container to the outside of the housing and are operable in response to temperature and pressure fluxuations inside the container for exhalation of warmed air from the container and for inhalation of cooled air into the container from outside the housing. Cooling of the air inside the container is purposely retarded whereby the operation of the valve for connecting the container to the outside of the housing for inhalation is delayed until the outdoor air temperature has decreased sufficiently to condense water vapor out of the outside air.

BACKGROUND OF THE INVENTION 
This invention, in its broadest aspect, pertains to the utilization of 
naturally occurring variations in ambient outdoor temperature to reduce 
water vapor in the air inside a storage container the contents of which 
may suffer damage or deterioration should such water vapor condense 
thereupon. 
The dehumidifier construction disclosed herein is operable to vent air from 
inside a storage container when such air is heated and expanded in 
response to the natural daytime rise in ambient temperature and to admit 
outside air into the container when the air inside is cooled and 
contracted in response to the natural nighttime drop in ambient 
temperature. If there is no temperature differential between air inside 
and outside the container, a balanced pressure condition exists and no air 
will be forced either into or out of the container through its vents. 
Cyclic or reversible air flow as described above is commonly characterized 
as a breathing action or respiratory function of the container. 
Housings of this type which exhibit breathing action are disclosed in a 
Solar Activated Dehumidifier described in U.S. Pat. No. 2,462,952 issued 
to Dunkak and in a Solar Powered Dehumidifier Apparatus described in U.S. 
Pat. No. 4,242,112 issued to Jebens. These prior art dehumidifiers are of 
a passive class which utilize a dessicant, such as dried silica gel, to 
absorb water from ambient air before it is inhaled into a closed housing. 
Such preconditioning of ambient air by means of a dessicant prior to 
inhalation into a housing is preferred over the well-known refrigerating 
class of dehumidifiers which consume large quantities of power in order to 
maintain the temperature and vapor density of air inside the housing at 
critical levels which forstall unwanted condensation on the housing walls 
and on objects disposed inside the housing. Nonetheless, both Dunkak and 
Jebens cite the relatively high energy consumption and cost involved in 
periodic reactivation of dessicant material by conventional electric 
heating elements and fueled burners. To overcome this energy related 
shortcoming of dessicant type air dryers, the aforenoted inventors propose 
that solar radiation be used as the sole or primary heat source for 
releasing accumulated moisture from their respective dessicant bodies. 
Both of these prior art devices also utilize that air periodically exhaled 
from the heat-pressurized housing interior as a source of purging air to 
convey moisture from the dessicant body to ambient. 
While passive dehumidifiers employing solar activated dessicants to 
precondition breathing air for a housing appear to display some operating 
cost advantage over air refrigerating dehumidifiers, several shortcomings 
remain. 
The need for prolonged solar exposure restricts the choice of location of 
the dessicant body to a normally sunny site; and, since the dessicant body 
and the housing it serves are usually physically attached or in close 
proximity, the choice of a less sunny location for the housing, itself, 
may be unavailable. 
To reactivate a body of dessicant material by solar heating, the dessicant 
material must be subjected to temperatures in excess of 300.degree. F. for 
a drying period related to the mass of the dessicant body. To assure that 
solar heating is sufficient to cause the dessicant to give up its 
accumulated moisture, both Dunkak and Jebens suggest that special lenses 
or mirrors be positioned between the dessicant body and the sun to 
concentrate solar rays to effect superheating of the dessicant. Solar 
tracking apparatus for maintaining the most advantageous position of the 
lenses has also been proposed. Obviously, association of such auxilliary 
devices with the dehumidifier apparatus would result in higher initial 
cost and ongoing structural vulnerability to adverse outside conditions 
such as wind, rain, hail and airborne particulates. 
Where a dehumidifier depends exclusively upon periodic exposure to direct 
sunlight for proper maintainence of one of its most critical operating 
elements, i.e. its dessicant body, such a device may be only marginally 
efficient on a partly cloudy day; moreover, after a succession of cloudy 
days, the dessicant will likely become fully saturated and the 
dehumidifier will fail altogether. Provision of an oversized dessicant 
body will provide a margin of safety against dessicant failure but with 
accompanying increases in dessicant cost, bulkiness and reactivation time. 
Moreover, where uncertainty regarding the frequency and duration of 
sunlight renders the risk of dessicant failure absolutely unacceptable, a 
standby, conventionally powered dehumidifier must be kept ready in case of 
such failure thereby defeating in large part the major purpose of a 
passive dehumidifier. 
If the volume of a housing to be dehumidified were sizable, as would be the 
case for a box-like container dimensioned for storing an automobile, a 
substantial mass of dessicant material would be required to dry 
efficiently such a large volume of air to be inhaled into the housing. 
Provision of ample dessicant would be expensive; and, the bulk of the 
required dessicant body would be cumbersome to install initially and to 
replace from time to time as required. Likewise, a storage space suitably 
sized to accommodate the dessicant body would significantly increase the 
overall size and cost of the dehumidifier apparatus. 
The foregoing recitation of the problems which remain in the construction 
and application of conventional passive dehumidifier devices of the 
respiratory type suggests that a substantial change in concept and design 
is needed to provide an improved passive dehumidifier which exhibits these 
surprisingly different characteristics and capabilities: 
1. No air drying agent such as dessicant material is required. 
2. Preconditioning of inhaled air is independent of the availability of 
sunlight as a reliable source of radiant energy. 
3. Daily respiration of the housing can be managed so that inhalation and 
exhalation occur only as and when outside air conditions favor efficient 
dehumidification of the housing. 
SUMMARY OF THE INVENTION 
A general object of this invention is to provide a passive dehumidifier for 
a breather type housing which overcomes the aforementioned shortcomings of 
prior art devices intended for this purpose. 
A primary object of this invention is to provide a housing which inhales 
air from the surrounding atmosphere only after some part of the water 
vapor in such air has been removed naturally due to atmospheric cooling 
below the dew point. This object is essentially achieved by insulating the 
housing and by providing air pressure responsive valve means for 
controlling air flow into and out of the housing interior. The purpose of 
the insulation means is to cause cyclic temperature fluxuations occurring 
inside the housing to lag antecedent cyclic temperature fluxuations 
occurring naturally outside the housing. Because the commencement of 
nighttime cooling of air inside the housing from an elevated daytime 
temperature is delayed by the housing insulation means, commencement of 
inhalation of ambient air is delayed accordingly until the housing air 
cools and contracts sufficiently to draw additional ambient air through 
the flow control means into the housing. Prior to commencement of such 
purposely delayed inhalation, the outside air temperature will have fallen 
below the dew point; and, accordingly, the somewhat drier outside air 
thereafter drawn in can be thought of as having been favorably 
preconditioned, i.e. dehumidified by natural means prior to inhalation. 
Another aspect of this invention is the provision of a sealed housing 
communicating to the outside through pressure responsive inlet and outlet 
valve means that regulate inhalation and exhalation of air to and from the 
housing interior. To this end, the outlet valve is normally closed but 
opens to allow exhalation whenever positive housing air pressure only 
slightly exceeds ambient air pressure; however, the normally closed inlet 
valve opens to allow inhalation only after the housing air pressure is 
reduced to a predetermined and preset point below ambient air pressure. 
Exhalation of air along with unwanted water vapor from the housing will 
occur whenever the volume of air inside the housing expands due to its 
being heated sufficiently to create an internal housing air pressure 
sufficient to overcome the threshhold resistance to opening of the outlet 
valve means. Heat effective to raise the housing air pressure is produced 
by solar heating of the ambient air and the subsequent transfer of such 
heat by convection and conduction to and through the insulated walls of 
the housing to the volume of air inside the housing. If the housing is 
situated to receive direct sunlight, radiant solar energy will also be 
absorded by the housing and transferred to the inside air. 
As indicated above, a key feature of this invention is achieved by 
purposely delaying inhalation of ambient air into the housing until 
ambient temperature has dropped below the dew point whereby the absolute 
humidity of the inhaled air will be reduced. To extend further that period 
of the delay before inhalation achieved by insulating the housing, the 
threshhold opening pressure of the inlet valve means may be adjusted to 
have a somewhat greater value than some anticipated ambient air pressure 
at which inhalation would otherwise commence. 
A further aspect of this invention is the utilization of yet another means 
for delaying the nighttime cooling of the air inside the housing whereby 
inhalation occurs only after ambient air has been predried naturally by 
nighttime cooling down to the dewpoint. This additional means comprises a 
heat absorbant body disposed inside the housing; and, since the housing of 
this invention is primarily intended as a storage container, the required 
body may conveniently and, somewhat surprisingly, comprise the stored item 
or items per se. To the extent that a stored object acts as a body capable 
of receiving and releasing heat, it functions as a heat sink which absorbs 
heat over a daylight period and later radiates such heat back to the 
surrounding air inside the housing. Since the absorbed heat is not 
dissipated instantaneously and since the air inside the housing and the 
insulation about the housing are poor heat conductors, the heat sink 
effect of a large, metallic item, such as an automobile, for example, 
comprises another means for achieving beneficial delay in inhalation. 
Yet another object of this invention is to provide a simple valve means 
which permits pressure induced breathing by a closed container or housing 
in the manner and for the purposes stated hereinbefore, yet prevents 
diffusion of ambient water vapor into the housing when ambient air 
pressure and the housing air pressure are in equilibrium. 
Other specific objects are to provide passively dehumidified storage means 
which may include some or all of the following advantageous features: 
No dessicant or other air-drying agent need be employed or reconditioned. 
No energy source other that naturally occurring atmospheric warming is 
required. 
The storage means may be sited anywhere out of doors without regard to 
conditions of sunlight or shade. 
The storage means may be located interiorly of a larger structure provided 
it remains subject to daily fluxuations in outdoor temperature. 
The storage means and items placed therein require no inspection or 
maintenance over long periods of time. 
The hereindisclosed means for dehumidification permits the use of large 
housing structures capable of storing large, bulky items such as 
automobiles, for example. 
These and other advantages and objects of this invention and the manner of 
obtaining them will become apparent and the invention will be best 
appreciated and fully understood by having reference to the following 
detailed description of the invention taken in conjunction with the 
accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION 
The illustrative embodiment of the invention depicted in the drawings 
comprises a housing or container, indicated generally by numeral 10, made 
up of upright side wall panels 11 to 20, upright end wall panels 21 to 26, 
horizontal roof panels 27 to 31, and horizontal floor panels 32 to 36. The 
walls, roof and floor each comprise an assemblage of these modular panels 
having tongue and groove edges held in interfitting relationship by 
internally contained, interlocking cam latches, not shown. Such panels are 
commercially available and, therefore, do not require further description 
regarding their structural details or method of assembly. 
It is essential for efficient operation of this invention that housing 10 
be well insulated and substantially sealed against air leakage. To this 
end, each of the structural panels is laminated, as shown in FIGS. 4,5 and 
6, and comprises core 38 of rigid insulation with thin metallic laminae 40 
suitably bonded to its opposite sides. Thermal insulation of this type is 
commonly extruded of high density polystyrene or polyurethane having a 
thickness of about three to four inches which provides insulating R valves 
in the range of R19 to R36. The bonded laminae 40 or skin may comprise 20 
to 28 gauge galvanized metal which effectively prevents air from passing 
through the porous core 38. The tongue and groove joints between all panel 
edges may be provided with suitable gaskets or joint sealing compound to 
forestall interpanel leakage. An acceptable alternative housing may be 
made of other building materials such as plywood, for example, and other 
insulating materials and insulation installation technics are available. 
Since the interconnected panels 32 to 34 which make up the housing's floor 
may be heavily loaded in some applications of this invention, the foam 
core 38 of these panels may be internally reinforced and the laminae 40 
attached thereto may be made of somewhat heavier gage steel. 
One beneficial and well-suited application of this invention is suggested 
in FIG. 1 where an automobile A, depicted in phantom lines, is parked for 
long term storage inside the aforedescribed housing 10. The appropriate 
dimensions of the housing will be somewhat greater than those of the 
automobile in order to facilitate parking and to provide door opening 
clearance and head room. For example, a housing 10 dimensioned to receive 
a medium sized car might be 18 feet long, nine feet wide and six feet high 
in order to provide adequate clearance for the automobile and driver. The 
standard commercial width of an individual panel employed to fabricate 
housing 10 is four feet; however, panels 15, 20, 23 26, 31 and 36 have 
been somewhat reduced in width to provide the housing the desired overall 
length and width. The aforementioned cam latches inside the panels are 
operated by an insertable wrench, not shown; and, in the illustrative 
assemblage, the latches are accessible from the interior of housing 10 for 
all panels except panels 21, 22 and 23 which make up the front end closure 
and access means for the housing. Wrench openings 42 through these front 
end panels and side wall panels 11 and 16 provide exterior access to 
associated front panel cam latches. 
FIG. 6, of the drawings depicts, more or less diagrammatically, a pair of 
check valves indicated in their entireties by numerals 44 and 46, 
respectively. Both valves are of the ball check class and rely on the 
force of gravity acting on lightweight balls 48 and 50 to retain the same 
in their normally closed or seated condition. Ball 48 closes against the 
underlying seating surface 52 inside the enlarged cylindrical cavity 54; 
and, ball 50 closes against a similar seating surface 56 inside the cavity 
58. The valves, which may be molded of plastic material, have hollow 
extensions 60 and 62 mounted through the upright wall panels 13 and 18, 
respectively, of housing 10 for communication with the housing interior. 
The curvature of extensions 60 and 62 makes it possible for identical 
valve constructions to be mounted on the housing to extend vertically in 
opposite directions. It will be readily understood that rising air 
pressure inside housing 10 will lift ball 48 for exhalation of housing air 
through the discharge valve 44 while falling housing air pressure will 
allow ball 50 to lift to initiate inhalation of outside air into housing 
10 through the inlet valve 46. During the period when neither of valves 44 
or 46 is operated for lack of an air pressure differential between the 
housing interior and the air surrounding the housing, the seated ball 
actuators 48 and 50 check any unwanted diffusion of water vapor into 
housing 10. 
While both valves 44 and 46 function to allow air flow therethrough as a 
result of small differences between ambient air pressure and housing air 
pressure, the cracking or opening pressure of the inlet valve 46 may be 
increased to a pressure higher than that of the outlet valve 44 by 
increasing the deadweight of ball 50 a selected amount. The desirability 
of such an adjustment of the operation of valve 46 will be explained 
hereinafter. While two very simple oneway check valves have been 
disclosed, it will be apparent that any number of low pressure valves of 
various constructions are commercially available and can be utilized to 
control the breathing function of housing 10 in the fashion herein 
described. The inlet valve 44 may be equipped with a suitable filter or 
screen, not shown, at the bottom end of the cavity 54 to prevent 
inhalation of dust or other particulate matter into the housing 10. 
Owners of collector and antique automobiles will appreciate that, once 
isolated inside a housing 10 made according to this invention, such prized 
and often extremely valuable automobiles will be well protected during 
long term storage from rodents and insects inhabiting the vehicle, from 
dirt and dust accumulations on external and internal vehicle surfaces, and 
from accidental contacts with might dent or scratch the vehicle. Moreover, 
the insulation inside the housing's structural panels will have the good 
effect of ameliorating damage to classic finishes and furnishings due to 
sharp changes in temperature inside the housing and the automobile. Owners 
of such cars will fully appreciate these recited advantages of housing 10 
over less effective practices such as shrouding a stored vehicle with 
various fabric covers, storing the vehicle in a poorly enclosed shed or 
storing the vehicle in an unheated garage attached to his home. 
Not only is the housing 10 productive of the above enumerated advantages, 
but it also serves to reduce substantially or eliminate the principal 
cause of deterioration in stored automobiles, namely, the condensation of 
water vapor on metal surfaces commonly resulting in destructive 
electrolytic oxidation or corrosion. Very simply stated, during each 
daytime period, the sun warms outdoor air which picks up evaporated water 
as a vapor; and, during each nighttime period as the earth's atmosphere 
cools, such water vapor condenses when the outdoor air temperature drops 
to the dew point. Unfortunately, the iron and steel components of an 
automobile have a low specific heat and, when contacted by nighttime air, 
tend to cool down more rapidly than their environment. When the air 
temperature adjacent the automobile reaches the dew point, water vapor in 
the air condenses and is deposited on its cool surfaces. 
Since a storage housing constructed in accordance with this invention is 
never purged completely of air and water vapor, but rather is of the 
breather type, an object stored in the housing 10 will always be 
surrounded by an atmosphere which contains a quantity of moisture in the 
form of water vapor. If, however, the density of water vapor in the 
housing is somehow held below the saturated vapor density for a given 
housing temperature, the dew point will not be reached and unwanted water 
will not condense. Condensation can likewise be forestalled so long as the 
housing temperature is maintained above the dew point of the water vapor. 
This invention contemplates an apparatus having a passive method of 
operation which suppresses moisture condensation inside the storage 
housing 10 by managing both housing vapor density and housing temperature 
in a novel manner yet extremely simple and effective means. Essentially 
the combined effect of the insulated housing panels and the operation of 
outlet and inlet valves 44 and 46 conditions the air inside the housing in 
a manner that the likelyhood that dew will form inside the housing is 
greatly reduced, if not eliminated. 
OPERATION OF THE DISCLOSED EMBODIMENT 
An initial advantage for the user of this invention is that a desirable 
outdoor site for the container 10 may be selected without regard to the 
availability of direct sunlight. Energy sufficient for carrying out its 
dehumidifying function will be supplied to the container so long as the 
air inside the container is cyclically cooled and heated by daytime solar 
heating and nighttime cooling of the atmosphere surrounding the container. 
The efficiency of the dehumidifying function should be satisfactory in 
those geographic regions in which daytime to nighttime temperature 
differentials are substantial and occur with daily or near daily 
regularity during all seasons of the year. Good results have been obtained 
where outside temperatures exhibit variations of at least 20.degree. F. 
between midnight and noon. Since exposure to direct sunlight is not 
necessary, although not undesirable, the container 10 or a plurality of 
similar containers may, if desired, be enclosed inside an available 
building or structure that provides enhanced physical security against 
tampering with the container or theft of its contents; provided that the 
temperature inside such other structure fluxuates substantially in the 
manner described above and provided that such other structure does not 
constrain the container's respiratory air flow. 
With the automobile A parked in an erected housing 10, the end wall panels 
21, 22 and 23 are locked in place to render the enclosed space defined by 
the container 10 substantially airtight. While the container need not be 
hermetically sealed to operate effectively, the total air leakage between 
the assembled structural panels must be so constrained that the 
respiratory function of the container is not inhibited and so that no more 
than a minimal amount of water vapor is allowed to enter the container by 
diffusion. 
During daytime hours, i.e. from sunrise to sunset, the earth's atmosphere, 
including the air mass immediately surrounding the container 10, can be 
expected to warm gradually to a daytime high. Subsequently, during the 
nighttime hours, the air about the container 10 will cool off to a minimum 
temperature sometime after sundown. The well understood effect of this 
daily temperature fluxuation on the volume of air substantially sealed 
inside container 10 is an increase in pressure inside the container in 
response to daytime heating followed by a pressure decrease in response to 
nighttime cooling. Whenever the air pressure inside the container 10 rises 
above the threshhold opening pressure of the discharge valve 44, air 
containing a quantity of water vapor, will be belched through the valve to 
atmosphere until the internal pressure of the container falls to a level 
insufficient to lift the deadweight of ball 48. This discharge of air and 
water vapor may occur frequently during the day until the daytime 
temperature inside the container reaches its maximum and then begins to 
cool. As a result of this day-time process of exhausting some of the water 
vapor from the container, the vapor density of the air remaining inside 
the container will fall to its lowest daily level and the temperature of 
the residual water vapor will likely remain well above the dew point 
during the day. 
As ambient temperature begins to cool from a daytime high, the temperature 
and pressure of the air inside container 10 will remain for some time at a 
higher level than otherwise would be the case if the walls, roof and floor 
of the container were not insulated by the core components 38 of the 
structural panels 11-36. As the heat contained in the warmer inside air is 
gradually transferred by conduction and convection through the walls of 
housing components, the inside temperature will begin to fall but only 
after an antecedent drop in outside temperature. The intended effect of 
the housing insulation is to create a condition in which the dropping 
inside temperature will lag behind that outside the container. This lag, 
intentionally induced by insulating the housing, can be beneficially 
prolonged by the aforedescribed heat sink effect of the stored automobile, 
i.e. the heat from this cooling metallic mass is dissipated by radiation 
to the surrounding inside air to further delay cooling inside housing 10. 
After atmospheric cooling causes the inside air to begin to contract due to 
loss of its daytime acquired heat and dissipation of heat from the 
automobile mass, the air pressure inside the housing will drop below 
ambient air pressure and eventually produce a differential pressure across 
inlet valve 46 capable of lifting the ball 50 upwardly from its seat 56. 
Outside air will then be lifted through the inlet valve only until the 
ball 50 subsequently reseats due to rising air pressure inside container 
10. During each such inhalation, a volume or gulp of air at ambient water 
vapor density mixes with that air inside the container to raise 
incrementally the inside vapor density. It is the main purpose of this 
invention to delay, by the means described above, the initiation of air 
inhalation and the resulting mixing of warm inside and cool outside air 
resulting in a higher inside vapor density and movement of the inside 
temperature toward the dew point of the air and water vapor mixture in the 
housing. This objective is achieved in part by delaying the occurrence of 
conditions inside the housing which cause opening of the inlet valve 46 
until the outside air has already cooled enough to produce a significant 
reduction in vapor density due to a loss of moisture in the form of dew. 
In addition to the combined effects of insulating the housing 10 and 
utilization of heat dissipated from the stored automobile body A, a third 
distinct but coactive means for retarding inhalation until the outside air 
is dried by partial condensation of its vapor content is employed in the 
operation of this invention. The latter means comprises an inlet valve 46 
in which the actuator ball 50 has a deadweight that can be overcome by a 
pressure differential produced only after cooling and contraction of the 
housing volume has progressed to an extent that outside air temperature 
has dropped below the dew point and has been dried accordingly. During 
this delay in inhalation induced by requiring a greater pressure 
differential to open inlet valve 46, falling pressure inside housing 10 
will lower the vapor pressure therein so that vapor condensation is 
inhibited even though the vapor may be cooling as outside air temperature 
gradually drops. However, negative housing pressure should not be allowed 
to fall so far that the seals between the structural components of the 
housing deteriorate or fail. 
While the embodiment illustrated comprises an automobile size container, it 
will be appreciated that larger or smaller breathing containers can be 
supplied with preconditioned, predried air by using the structure and 
method of operation disclosed herein. 
The foregoing description of the embodiment of the invention shown in the 
drawings is illustrative and explanatory only; and, various changes in the 
size, shape and materials, as well as in specific details of the 
illustrated construction, may be made without departing from the scope of 
the invention. Therefore, I do not intend to be limited to the details 
shown and described herein, but intend to cover all changes and 
modifications which are encompassed by the scope and spirit of the 
appended claims.