Air pallet having multiple entry integrated air inlet valves

An air pallet such as a patient mover which may be formed of upper and lower thin flexible film sheets sealed at their edges to form a plenum chamber therebetween, functions to move with minimal friction, a load supported by a generally rigid planar backing member, which may be the load itself, over an underlying generally planar fixed support surface. The bottom thin flexible material sheet is perforated by small diameter perforations such as pin holes at the load imprint area. Dual opposed air inlets permit pressurization of the plenum chamber by insertion of a wand connected to a source of pressurized air into one of the air inlets. Air escaping from the perforations creates an air bearing between the fixed support surface and the bottom thin flexible film material sheet. A pair of flexible strips are interposed at laterally opposed inlets within the plenum chamber and extend across the chamber from opposed edges of the air pallet with the free ends of the strips overlapped. Air inlet openings are formed at respective edges where the flexible strips and the flexible sheets are sealed together between one side of each strip and an adjacent thin flexible film sheet. Both strip side edges are preferably sealed to said other flexible film sheets form defined air passages, inwardly of the inlet openings. Automatically, at the insertion of a wand bearing air under pressure into the opening at one side of the air pallet, as a result of air flow, between the strip overlappings, a strip acts to seal the opening at the opposite side of the air pallet prior to air pressurization of the plenum chamber by air flow from between the overlapping portions of the flexible film strips into said plenum chamber.

BACKGROUND OF THE INVENTION 
The present invention has application to an air pallet generally such as 
that set forth in U.S. Pat. No. 3,948,344 entitled "LOW COST AIR LET 
MATERIAL HANDLING SYSTEM" issued Apr. 6, 1976, and in particular to an air 
bearing patient mover such as that set forth in U.S. Pat. No. 4,272,856 
entitled "DISPOSABLE AIR-BEARING PATIENT MOVER AND VALVE EMPLOYED THEREIN" 
issued June 16, 1981, of which I am coinventor. Planar air pallets of such 
type employ at least one flexible material sheet for partially defining a 
plenum chamber with said one sheet being perforated as by way of small pin 
holes over a surface area defined by the imprint of the load, which pin 
holes face an underlying fixed, generally planar support surface. When the 
plenum chamber is pressurized by low pressure air, the escape of air under 
pressure through the minute perforations, which open directly to the 
interior of the plenum chamber, acts to initially jack the load above the 
flexible sheet and to create a frictionless air film bearing of relatively 
small height between the support surface and the bottom of the perforated 
flexible sheet. 
In all air pallets including patient movers, it is necessary to provide 
controlled pillowing of the flexible film or films which may define 
partially or completely the plenum chamber and to thus establish, by 
jacking the load to a predetermined height, the ability of the air pallet 
to ride over surface projections on the underlying support surface. At the 
same time, excess pressurization of the plenum chamber may cause 
ballooning of the thin film flexible sheet or sheets, resulting in tilting 
and rolling of the load off the top of the air pallet. When the load rests 
on the air pallet prior to pressurization of the plenum chamber, the load 
tends to press the perforated flexible sheet or sheets into contact with 
the floor and prevent the entry of air under pressure into the plenum 
chamber and the subsequent escape of air through the perforations. Air 
dispersion means are required either interiorly of the plenum chamber or 
by way of means exterior of the plenum chamber to ensure pressurization of 
the plenum chamber. Additionally, to permit selective multiple air flow 
entry to the plenum chamber, such as at the four corners of the patient 
mover type of air pallet exemplified by U.S. Pat. No. 4,272,856, openings 
are required within the sealed wall of the dual flexible sheets defining 
the plenum chamber, either at the sealed edge interface of dual, upper and 
lower thin flexible sheets, or otherwise. Valve members have been 
incorporated at the various inlets such that, automatically by air 
pressurization of the plenum chamber through one of the inlets, the valve 
members at the other inlets close off those unused inlets to prevent 
escape of air. 
In U.S. Pat. No. 3,948,344, the valves are constituted by the provision of 
a flap formed at each air inlet as an extension of one of the thin 
flexible sheets defining a wall of the plenum chamber, such as the bottom 
flexible sheet bearing the perforations and creating the air bearing. With 
that flap being a bent over a portion of the sheet internally of the inlet 
and projecting inwardly into the plenum chamber, by contacting an 
overlying or underlying opposed sheet or wall member, it functions to seal 
off and prevent the escape of air through an air inlet at that point by 
being held in sealing position by developed internal air pressure. 
With respect to the patient mover as exemplified by U.S. Pat. No. 
4,272,856, each of the multiple air inlets is comprised of at least one 
outer tube formed of a thin, flexible film material and an inner tube 
mounted coaxially within the outer tube and comprised of opposed flexible 
tongues sealed at the ends remote from the plenum chamber to opposite 
sides of the outer tube with their inner ends being free of each other and 
from the outer tube. The tongues constitute strips of material of less 
flexibility than that of the thin flexible film sheets defining either the 
bottom or top and bottom of the air pallet plenum chamber. As such, during 
air entry into the plenum chamber through the inlet, the tongues take the 
curved configuration of the outer tube and are in contact therewith. After 
pressurization of the plenum chamber, air tending to escape through the 
inlet causes the tongues to move away from one of the outer tube walls and 
to press against each other and against the other of the outer tube walls 
to thereby close off the inlet means. Where multiple inlets are provided, 
automatically as a result of pressurization of the plenum chamber through 
one of the inlets, the other unused inlet or inlets are closed off by 
movement of the tongues away from the outer tube and into contact with 
each other. 
Where the air pallet takes the form of a patient mover, it is desirable to 
pressurize the plenum chamber starting at the end of the patient mover 
where the head of the patient rests such that the patient's head rises 
first during pressurization of the plenum chamber. Jacking of the patient 
upwardly as a result of plenum chamber pressurization occurs prior to the 
creation of the air bearing by air escaping from the perforations of the 
bottom thin flexible sheet. Preferably the air inlet means can be 
eliminated from the opposite end of the patient mover type of air pallet. 
Further, it is necessary to insure that during pressurization of the 
plenum chamber, air does not escape through the second air inlet at the 
head end of the patient mover to the opposite side, or from any 
intersecting position as for instance at the same corner, but 
perpendicular thereto, from that receiving the wand and being subjected to 
the initial on rush of air under light pressure. 
It is, therefore, a primary object of the present invention to provide an 
improved air pallet and, particularly for a patient mover use in which 
there is an integration between dual air inlets and their valves of the 
air pallet which intersects at the same end or extend from both ends of 
the air pallet, and in which sealing of unused air inlet is insured prior 
to pressurization of the plenum chamber. 
SUMMARY OF THE INVENTION 
The invention is directed to an improved air pallet for the frictionless 
movement of a load supported by a generally rigid planar backing member 
over underlying generally planar fixed support surface where the air 
pallet comprises top and bottom walls defining a plenum chamber with at 
least the bottom wall being formed of a thin flexible sheet material. The 
bottom wall includes a portion defined by the footprint of the load having 
a plurality of closely spaced small diameter perforations opening directly 
into the plenum chamber. Air dispersion means ensures air flow throughout 
the plenum chamber when the air pallet is under load at the time of air 
pressurization of the plenum chamber. Means are provided for controlling 
pillowing of the flexible sheet material to permit jacking of the backing 
member and the load sufficient to allow the air pallet to accommodate 
surface irregularities of the load support surface and the backing member, 
while preventing ballooning of the thin flexible sheet material. Air inlet 
means open to the plenum chamber for permitting low pressure air flow into 
the plenum chamber for jacking of the load and for subsequent discharge 
through the perforations to cause an air film between the bottom wall and 
the fixed support surface. 
The improvement lies in the air inlet means comprising a pair of thin 
flexible material strips extending transversely, internally of the top and 
bottom walls along intersecting paths, being of a given width and each 
strip having one outer lateral edge sealed to a respective one of the top 
and bottom walls along an edge and being free of the other wall at that 
edge at least over a portion thereof to form at the non-sealed edge 
portion, an air inlet opening to the interior of the air pallet at a given 
side and in line with the opposite side air inlet. The width of the strips 
are such that the inner ends remote from the air inlet openings overlap 
each other, whereby upon insertion of a wand bearing air under pressure 
into one of the air inlet openings, this causes automatically, as a result 
of the air entry blast, the overlapped portion of one of the strips to 
press against a given one of the upper and lower walls to close off the 
air inlet opening not receiving the wand. Thus, the air inlet not subject 
to air pressurization is effectively and immediately sealed off, this 
facilitating the air dispersion throughout the plenum chamber, the jacking 
of the load, and the creation of the thin film air bearing beneath the 
bottom wall sheet and the underlying generally rigid support surface. 
Preferably, the thin flexible sheets are additionally sealed along their 
edges proximate to the plenum chamber, at right angles to the inlet 
opening, throughout their length including the overlapped portions to 
respective ones of the top and bottom walls to cause pressurization of the 
plenum chamber and air flow to the plenum chamber subsequent to air 
passing completely through the air flow passage created by the selected 
one of the edge sealed overlapping strips partially defining the active 
inlet.

DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring to FIGS. 1-6 inclusive, there is shown a preferred embodiment of 
the air pallet of the present invention taking the form of a patient mover 
which is essentially of bag form. The air pallet or patient mover 
indicated generally at 10 is defined principally by an upper or top thin, 
flexible sheet indicated generally at 12 and a lower or bottom thin, 
flexible sheet indicated generally at 14. Each sheets may be formed of 
similar thin, flexible film material such as polyvinyl chloride or 
polypropylene, of several mills thickness. The sheets may be sealed 
together by the localized application of heat to thermo-bond the sheets 
together, or by sewing the flexible sheets together at their edges, or 
otherwise. By bonding or sewing the sheets together about their edges, 
there is defined internally a sealed cavity or air plenum chamber 16. As 
desired, and in keeping with U.S. Pat. No. 4,272,856, portions of the 
contacting upper and lower sheets 12 and 14 may be sealed together or 
sealed off from the central plenum chamber 16 underlying the area of the 
load defined by the patient P. It is noted that the patient P has his head 
H resting on a central portion of the air pallet, at one end, with his 
torso T extending away therefrom and with at least portions of the 
patient's legs L extending beyond the other end of the air pallet or 
patient mover 10. 
The air pallet may incorporate a relatively rigid backing member such as a 
semi-flexible plastic sheet 18 within the structure of the patient mover 
plenum chamber 16 as desired and according to member 34 of U.S. Pat. No. 
4,272,856. 
Important to the correlation between the air bearing and footprint of the 
load is the requirement that the lower thin flexible sheet 14 be provided 
with a plurality of very small diameter, pinhole-type perforations as at 
20 underlying the load bearing area or load footprint, such that when the 
plenum chamber 16 is pressurized with a low pressure gas such as 
compressed air, the escape of air through the literally thousands of 
perforations 20 creates a minimial height, low cfm, low pressure air 
bearing as at 22, FIG. 1. 
The present invention is keyed to the improvement in dual air inlet means 
for effectively pressurizing the plenum chamber 16 and developing the air 
bearing 22. In accordance with the prior referred to patents, this is 
achieved utilizing a suitable air compressor which may be portable or 
otherwise and which includes an air delivery tube or wand 31. Particularly 
where the air pallet comprises a patient mover, it is preferred to supply 
the air to the portion 16a of plenum chamber 16 underlying the head H of 
the patient P such that, initially, as the plenum chamber 16 is 
pressurized, the patient's head H is jacked upwardly prior to any lifting 
of the chest or other part of the torso T. The air pallet is required to 
have a pair of air inlets to opposite sides at one corner, opposite ends, 
etc., and the invention is directed to such multiple entry inlets having 
integrated, intersecting air inlet valves for controlled instantaneous and 
effective sealing of one inlet as the wand bearing air under pressure 
inserted ito the other inlet is supplied with pressurized air for 
pressurization of the plenum chamber 16 and the creation of the air 
bearing 22. Air inlets indicated generally at 24 and 26, respectively, are 
provided in the illustrated embodiments, FIG. 1, to the right and left of 
the air pallet 10 at the head and foot thereof, and are formed in a 
simplified manner. In that respect, other than upper and lower sheets 12 
and 14, the sole remaining elements of air inlets 24 and 26 comprise 
elongated rectangular thin film strips, indicated generally at 28 and 30, 
respectively. Right side strip 28 and left side strip 30 are interposed 
between upper and lower sheets 12 and 14, at the top or head end of the 
air pallet or patient mover 10. Strips 28 and 30 are slightly longer than 
one-half the width of sheets 12 and 14 and are sandwiched between sheets 
12 and 14, with their free inner ends overlapped. 
Further, both upper sheet 12 and strip 28 are provided with arcuate cutouts 
as at 12a and 28a, respectively. Strip 28 is thermobonded, or stitched 
along upper edge 28b and lower edge 28c to lower sheet 14. The two arcuate 
cut edges 12a and 28a of sheet 12 and strip 28, respectively, are 
thermobonded or heat sealed to each other, and the straight portion 28d of 
right edge of strip 28 is heat sealed or stitched to and between sheets 12 
and 14 at their right side meeting edges, while the left edge 28e of strip 
28 is free. 
Likewise, for strip 30, the arrangement is similar. That is, strip 30 being 
of a length which is slightly wider than one-half the width of the sheets 
12 and 14, overlaps strip 28 at its interior. Thus, the strips 28, 30 have 
free ends which intersect each other and are overlapped at that 
intersection to perform self-sealing valving functions. Left edge 30d of 
strip 30 is positioned between left side edges of sheets 12 and 14 and 
that edge 30d is heat sealed or stitched to bottom sheet 14 to create an 
effective gas tight seal therebetween. The straight edge 30d of strip 30 
is edge sealed along its complete height to the bottom sheet 14, and is 
sealed to the upper sheet 12, over a short distance up unto the point 
where arcuate cutout 12d appears within the upper sheet 12. Further, strip 
30 is sealed along its upper edge 30b, to and between upper and lower 
sheets 12, 14, while lower edge 30c is sealed solely to upper sheet 12, 
along that edge. 
This has the effect of leaving the inner edge 30e of strip 30 free although 
overlapped relative to strip 28. 
As may be appreciated, the sandwiching of the inner edge overlapped strips 
28 and 30 between upper and lower thin flexible sheets 12 and 14 and the 
sealing of the same along certain edges to given ones of said sheets have 
the effect of producing tubular air flow passages 34 and 40 for inlets 24 
and 26, respectively. The effect is also to integrate the thin flexible 
strips so as to act as valves functioning to seal off air flow from the 
air inlet not being employed for pressurization of plenum chamber 16 
during operation of the air pallet or patient mover 10. 
Unlike prior U.S. Pat. No. 4,272,856, there is no elastic memory necessary 
for strips 28 and 30. As may be appreciated, they are normally flat but 
they have the property of being deflected due to their flexibility to 
match the change in surface configuration of the flexible sheets 12 and 14 
to which they are integrated. 
Important to the appreciation of the improvement resides in the action 
resulting from insertion of a wand bearing air under pressure such as wand 
31 into a selected inlet 24 or 26, the nature of the pressurized air flow 
in pressurization of plenum chamber 16, jacking of the load, and 
importantly, the lifting of head H of the patient prior to lifting of the 
patient's torso T, and the automatic sealing of the other air inlet by the 
integrated valve at that inlet constituted by one of the inner edge 
overlapped flexible strips. The operation by air pressurization through 
inlets 24 and 26 in a selective manner may be appreciated by specific 
reference to FIGS. 3 and 6. 
In FIGS. 3, 4 and 5, an air tube or wand 31 is inserted, from right to 
left, into air inlet passage 34 by projecting the leading end of the wand 
31 through inlet opening 36 of left side inlet 24, beneath strip 28 and 
above the underlying bottom thin flexible sheet 14. The on rush of air is 
captured within air passage 34 and moves from right to left, until it 
meets the sealed left side edge 30d of overlapping strip 30 and left side 
edge 14b of thin flexible bottom sheet 14 of the air pallet. Due to the 
overlapping of the left side flexible strip 30 relative to right side 
strip 28, the air tries to escape from between the overlapped edges 28e, 
30e of strips 28 and 30 by reversing its flow back towards inlet 24. Since 
the overlapped edges of strips 28 and 30 are free of each other, the air 
escapes from between the strips, and in escaping, tends to press the right 
free edge 30e of strip 30 upwardly against the upper thin flexible sheet 
12, functioning automatically to seal off inlet opening 38. At that time, 
air is free to move into the plenum chamber 16 by passage between edge 28c 
of strip 28 and the upper thin flexible sheet 12, as well as passing into 
the plenum chamber 16 by passage between edge 30c of left side strip 30 
and the bottom thin flexible sheet 14, which are not sealed together along 
edge 30c. 
Thus, a key aspect of the invention is the automatic forced closure of the 
opposite side or otherwise intersecting air inlet valve at the inlet not 
being utilized for pressurization of the plenum chamber 16 and the 
subsequent creation of the air film bearing beneath the air pallet or 
patient mover. The effect of the initial air blast into a given inlet 24 
from wand 31 across the air pallet, and towards the opposite seal between 
the bottom sheet and strip 30, is to flip up the inner free end of strip 
30 towards the top thin flexible sheet 12 and to seal off opening 38 of 
the opposite side inlet 26. 
Referring next to FIG. 6, the insertion of pressurized air carrying wand 
31, into the inlet opening 38 and between strip 30 and the uper thin 
flexible sheet 12, causes the air to flow from left to right, initially 
through air passage 40 across the overlapped upper edge 30e of strip 30, 
and into the space between strip 28 and upper thin flexible sheet 12. This 
will cause deflection of the underlapped inner edge 28e of strip 30 
downwardly against the bottom thin flexible sheet 14 to seal off right 
side inlet opening 36 and to cause air flowing from between the overlapped 
edges of strips 28 and 30 to enter plenum chamber 16 from the space 
between the bottom of right side strip 30 and the underlying thin flexible 
sheet 14, across the unsealed edge 30c of the right side strip 30. 
Meanwhile, air also enters the plenum chamber between the unsealed edge 28c 
of the right side strip 28 and the top thin flexible sheet member 12. As 
is depicted in FIG. 6, the initial air blast causes instantaneously and 
automatically an effective pneumatic force pressing the free edge 28e of 
strip 28 downwardly to seal off inlet opening 36 at the unused left hand 
air inlet 24 of the air pallet or patient mover 10. 
While the illustrated embodiment has been described in conjunction with an 
arrangement wherein upper edges 28b of strip 28 and 30b of strip 30 are 
described as being sealed to and between upper and lower thin flexible 
sheets 12 and 14 of the air pallet, as seen in FIG. 7, where like elements 
bear like numerals, it is not necessary that either upper or lower 
transverse edges of strips 28 and 30 be sealed to appropriate sheets 12, 
14. With respect to lower edges 28c for strip 28 and 30c for strip 30, 
these edges are not sealed to either top and bottom sheets 14 and 12, 
respectively, although such structural arrangement insures the desired 
sequence of sealing off of the opening of the non-used air inlet prior to 
the plenum chamber 16 being pressurized by air flow into one of said 
inlets, and thence, jacking of the load upwardly and the creation of air 
bearing 22. Edges 28b and 30b, respectively of strips 28 and 30, are 
sealed in the manner of the first embodiment. 
While the illustrated embodiments show the air inlet means as comprising a 
pair of thin flexible material strips extending transversely, internally 
of the top and bottom walls, and being of a strip length less than that of 
the width of the top and bottom walls, and while the opposed air inlets 
are at the top or head end of the patient mover type air pallet in the 
illustrated embodiments, the invention has application where they may not 
only be at the same end but the air inlets may be at right angles to each 
other at a common corner at their head end or foot end of the patinet type 
air pallet for example. Additionally, in this case, the air inlets and 
their flexible strips functioning as automatic valves intersect at right 
angles to each other rather than having overlapped intersecting portions, 
as in the illustrated embodiment, coming from opposite sides. In a further 
variation, which also is not shown, a strip and thus an inlet formed 
thereby may extend from the full length of the air pallet patient mover, 
for instance from the head end, while a laterally intersecting inlet and 
laterally intersecting strip may extend at right angles thereto from one 
side of the air pallet at the bottom or foot end of the air pallet. 
While the invention has been particularly shown and described with 
reference to a preferred embodiment thereof, it will be understood by 
those skilled in the art that the foregoing and other changes in form and 
details may be made therein without departing from the spirit and scope of 
the invention.