Note: Descriptions are shown in the official language in which they were submitted.
WO 93/11062 PCT/US91108550
AIR CHAMBER TYPE PATIENT MOVER
' Field Of The Invention
This invention relates to air pallets, and more particularly
'. to air pallet-type patient movers for facilitating comfortable
support of and transfer of patients and more particularly to a
semi-rigid air pallet in which a series of parallel, compressed
air filled tubes or the like form one or more backing chambers
which function as a generally rigid backing member.
Background Of The Invention
The present invention is an outgrowth of the development of
an air pallet using low pressure, low cfm air f low exemplified
by U.S. Patent No. 3,948,344 entitled, ~°'LOW COST PLANAR AIR
PALLET MATERIAL HANDLING SYSTEM", issued April 6, 1976, and U.S.
Patent No. 4,272,856 entitled, "DISPOSABLE AIR-BEARING PATIENT
MOVER AND VALVE EMPLOXED THEREIN" , issued June 16, 1981, assigned
to the common assignee. Planar air pallets and air-bearing
patient movers of such type employ at least a thin flexible
bottom sheet for partially deffining a plenum chamber, with said
one sheet being perforated by way of small, closely spaced pin
holes over a surface area defined by the imprint of the load,
which pin holes f ace an underlying fixed, generally planar
support surface. The pin holes open unrestrictedly to the
interior of the plenum chamber and to the planar support surface.
When the plenum chamber is pressurized by low pressure air,
initially the air jacks the load upwardly above the thin flexible
sheet, then air escapes under pressure through the minute pin
holes and creates a frictionless air bearing of relatively small
height between the underlying support surface and the bottom of
the perf or~ted~ f lexible sheet .
--In~ al-1 'air pallets, including patient movers, it is
necessary to provide controlled pillowing of the thin, flexible
sheet material, particularly outside the perforated surface area
of that sheet to initially j ack the load above the f lexible sheet
prior to the creation of the frictionless air bearing and ,to
insure the ability of the air pallet to ride over surface
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projections on the underlying support surface. Means must also
be provided within the air pallet to prevent ballooning of the
thin flexible sheet or flexible sheets defining the plenum
chamber whereby the plenum chamber takes a circular or near
circular vertical cross section, the result of which could be the
tilting or rolling of the load off the top of the air pallet.
Further, when the load rests on the air pallet, prior to the
pressurization of the plenum chamber the load tends to press the
perforated flexible sheet into contact with the underlying
support surface which prevents the entry of air under light
pressure into the plenum chamber. Thus air dispersion means are
required either interiorally or exteriorally of the plenum
chamber to ensure pressurization of the plenum chamber.
Under certain circumstances, the load may additionally
constitute a generally rigid, i.e., semi-rigid backing member.
A cardboard box filled with material for transport may have the
planar bottom functioning as a generally rigid backing member.
Where the air pallet is formed essentially of a thin flexible
sheet material bag, a bag of grain acting as the load may
constitute a generally rigid backing member.
In the development of air pallets and in particular air
bearing patient movers as a form of such air pallets as
exemplified by U.S. Patent 3,948,344, a corrugated sheet such as
sheet 34 within the single chamber functioning as a plenum
chamber in a patient mover formed by. two superimposed thin
flexible sheets 12, 14 in U.S. Patent 4,272,856 may constitute
both a unitary air dispersion means and a semi-rigid backing
member (if needed). The semi-rigid backing member may comprise
a semi-rigid.sheet inserted within a cavity formed between the
top-thin fl xible film sheet and an intermediate thin flexible
sheet. Alternatively, the backing member may be formed of a
series of transversely linked air pressurized tubes Formed by
sealing off parallel, laterally adjacent longitudinal sections
of the top sheet and the intermediate sheet. Such tubes may be
completely sealed and air pressurized through valves . In a f low-
WO 93/ 11062 pCT/US91 /0~~60
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through system, the pressurized air forming the air bearing
' passes first through parallel, transversely linked tubes defined
by the top and intermediate sheets and then into the plenum
' chamber defined by t~-,e intermediate sheet and the bottom sheet
with the bottom sheen bearing the pattern of perforations over
the foot print of the 7.:~ad. U.5. Patent 4,528,?04 issued to Jack
Wegener and Raynor D. ,~ohnsc~n,~co-applicants herein on July 16,
1985 and entitled Semi-Rigid Air Pallet Type Patient Mover is
directed to such air pallets.
Flow-through chambers connected by succeedingly smaller
sized ports within horizontally extending vertically spaced walls
define a series of stacked chambers in a gas pressurized jacking
structure and an air pallet including such jacking structure and
forms the subj ect matter of U . S . Patent 4 , 41? , 63 9 issued to Jack
Wegener, a co-applicant herein on November 29, 1983 entitled,
"DYNAMIC GAS PRESSURIZED JACKING STRUCTURE WITH IMPROLOAD
STABILITY AND AIR PALLET EMPLOYING SAME". Further, as evidenced
in Figure 10 thereof, such jacking structure may be formed
totally of thin f lexible sheet material with vertically separated
chambers in communication via a gas passage whose cross-sectional
area is smaller than that of the air inlet to the upper chamber
thereof through the air inlet hose.
In the semi-rigid air pallet type patient mover of U.S.
Patent 4,686,?19 assigned to the common corporate assignee and
entitled "SEMI-RIGID AIR PALLET TYPE PATIENT MOVER" , U-straps are
sewn to the lateral sides of the patient mover structure for
facilitating lateral shifting of the patient placed thereon with
the plenum chamber gas pressurized and a thin air film underlying
the perforate area of the thin f lexible bottom sheet . The
patient'may b'e bound to the top oz: the patient mover via a pair
of crossed ~~ELCRO~ hook and loop ma aerial covered straps for ease
in engagement and disengagement of the strap ends about the
patient.
In the field of air pallets, and particularly of the patient
mover type, those patient movers formed of multiple, thermal
V!'O 93/11062 Pf.'1"/U~91/08660
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bonded or stitched sheets of thin flexible sheet material which
incorporate a rigid or a semi-rigid sheet as the load backing
member are not universally employed within the hospital or other
treatment facility. The existence of the rigid or semi-rigid
sheet carried within a pocket or cavity defined by two thin
flexible sheets renders the assembly bulky, and adds considerably
to the weight of the same. While such patient mover may perform
extremely well at a certain hospital station or treatment area
such as facilitating patient movement onto and from an X-ray
machine, the patient mover remains at that area and is unlikely
to be employed in moving the patient to and from the hospital bed
remote from the X-ray area since hospital personnel resist
transporting such patient mover from location to location.
The same is true where the air pallets such as patient
movers are utilized by paramedics, shock trauma units or .the
like. As a result, recently there has been shown considerable
interest in the development of soft pad or hard pad air chamber
type air pallets as pat?ent movers or as patient positioners
devoid of such rigid or semi rigid sheet. In the health care
field, particularly the person transported or changed in position
in many cases is not truly a patient recovering from sickness
but, one requiring continuous attention, such as an invalid or
partial invalid. In this case, upon either transport, or
positioning and maintaining the patient comfortable in a given
partially upright or supine position, the possibility of a tissue
breakdown exists with the need for inducing therapy during the
time that the patient remains in such given positions for a
significant period of time. Essentially, there exists the need
for the prevention of skin breakdown which can occur within a
very.. short dime whether the patient is in a health care facility
or hospital, even while on the operating table of such hospital.
The applicants have determined that there are significant
differences between the rigid back air pallet and the flexible
or air chamber type air pallet with a load that can flex. In the
development of air pallets and air pallet-type patient movers
WO 93/11062 PCT/US91/0~660
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utilizing a thin, flexible bottom sheet partially defining a
plenum chamber and being perforated by way of thousands of small,
closely spaced pin holes over the surface area defined by the
imprint of the load and which open unrestrictedly to the interior
or the plenum chamber and to an underlying planar support
surface, such air pallets and air pallet-type patient movers have
generally employed a rigid backing member starting with U.S.
Patent 3,948,344. Exceptions lie in the patient mover of U.S.
Patent 4,272,856, and in the patient mover illustrated in
Figures 4 and 5 of U.S. Patent 4,528,704.
Certain structural features and parameters with respect
thereto play a very important part in the successful operation
of an air pallet having a rigid backing member. The first
consideration and operating parameter is that of load
distribution. By taking the weight of the load and dividing it
by the mass load footprint area in square inches, one obtains the
value of the air pressure in pounds per square inch required to
lift the load ar.,3 to move the load on a developed air film by the
escape of air from the perforations. By multiplying the width
of the load times its length, one obtains the value of the
footprint of the load in square inches. The plenum chamber in
such structure is usually defined by the rigid backing member and
the thin flexible bottom sheet bearing the perforations. The
area of the plenum chamber footprint in square inches is the
length of the plenum chamber multiplied by its width. The key
for successful movement of the load on a developed air film by
air escape from the perforations is to make the air work on the
load and to control the action of the air in doing that job. By
matching the footprint of the load to that of the plenum chamber
pattern area~of perforations, thus generally matching tr.e area
of the developed air film to that of the load, the air pallet
with the plenum chamber pressurized will jack the load, create
the air bearing and permit the load to be stably moved on the air
pallet: w
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If the mass of the load is spread through too small an area
against the plenum chamber, i.e., point loading, the load may
ground out the portion of the plenum chamber between that load
and the underlying planar support surface causing the thin
f lexible sheet to bulge out around the point load application
against the top of the plenum chamber. Thus, with the plenum
chamber up and about the sides of the load, the load is not
lifted, the air does not escape through the perforations and no
effective air bearing is created.
When the load footprint is less than the plenum chamber air
film footprint, a significantly greater pressure is needed to
lift the load.
Successful operation of rigid backing surface type air
pallets requires controlled jacking, controlled pillowing and
anti-ballooning. Control of load distribution may be achieved
by the use of a rigid backing member such as a board or sheet as
part of the plenum chamber, or within a separate chamber
supporting the load but overlying the plenum chamber. The. rigid
backing member distributes the load mass balanced equally over
the area of the plenum chamber footprint. The control of the
plenum chamber can be performed in several ways and a properly
designed plenum chamber can effect several of the control
functions, i.e., jacking, pillowing and ballooning.
The term "j asking" covers the act of raising the load so
that air can enter into and be distributed throughout a plenum
chamber, or multiple plenum chambers, and then pass out through
the perforations to form the air film or air bearing while
permitting the planar rigid backing surface to support the load
and allow it to move on the film of air.
:._
°-~.'he term "pillowing" describes the ability of the thin,
f lexible sheet to deform so as to ride over or under surface
irregularities in the generally planar support surface (ground,
floor, etc.) without bottoming out. If the compressed air within
the plenum chamber does not jack the load high enough, the rigid
WO 93/ 11062 PCl'/IJ~91 /08660
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backing member will ground out against the thin, flexible bottom
sheet and the surf ace irregularity (vertical projection).
The term ''ballooning'° covers the situation where the load
' is jacked or raised up so high that the load becomes unbalanced
on the footprint formed by the plenum chamber. This is normally
caused by the thin, flexible sheet tending to become
hemispherical (where a generally rigid planar backing member acts
in conjunction with the thin, flexible bottom sheet bearing the
perforations to form the plenum chamber). The hemispherical
configuration given to the thin, flexible bottom sheet permits
it to roll about the curved surf ace tilting to the extent where
the load may be dislodged. As may be appreciated, the pillowing
control functions as an anti-ballooning means. Absent the
generally rigid planar backing member, where the plenum chamber
is formed of thin, f~~xi~~ ~: sheet material such as a bag, the bag
will take a circular crc:~:~-section when fully pressurized, the
true essence of a balloc~ .
Where the thin, fle::y ble bottom sheet is tightly mounted at
opposite sides to the ge:-w;rally rigid backing member that rigid
backing member f~,.nctiw to control jacking, pillowing and
ballooning. Where the r~.gid backing member is smaller than the
thin, flexible bottom sheet, slack develops within the thin,
flexible bottom sheet which increases the pillowing capability
of the thin, f lexible bottom sheet. Excessive slack leads to
ballooning. .
Other means have been provided for controlling pillowing,
such as the lamination of additional members to a centex sheet
or to either the upper thin, flexible sheet or the bottom thin,
flexible sheet. The addition of internal strips lying diagonally
from ,corner: to corner within the plenum chamber or vertic,-~.I from
face to face, control the degree of pillowing. T:~e load itself
may act as a pillowing control means. The insertion of a rigid
plate internally within a thin, f lexible bag acts both as a rigid
backing member, a pillowing control means and under certain
conditions air distribution means for insuring air pressurization
WO 93/ 11062 1'~'/U~91 /O~i6b0
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of the plenum chamber with the air pallet formed principally by
the bag supporting the load prior to air pressurization of that
plenum chamber. The size of the blower and thus the air pressure
developed within the plenum chamber may constitute pillowing
control means, as may valuing or gating of the air f low system
entering the plenum chamber and creating the air bearing, and the
stiffness or flexibility of the material used in forming the
thin, f lexible bottom sheet . The area of the material around the
perforation pattern and between that pattern and the rigid
backing member is normally the primarily pillowing control means
for such air pallets. The proximity of the perforation pattern
to the outside edge of the plenum chamber, the slack in the
plenum chamber and the rigidity of the backing member all
constitute aspects of the pillowing control.
In U.S. Patent 4,272,856 for an operative air pallet-type
patient mover, pillowing is controlled by having the pattern of
perforations extending to the edge of the plenum chamber and the
sides of the plenum chamber are purposely designed to match the
head and torso of the patient from the shoulders to the hip,
where the load mass of the patient is concentrated.
In U.S. Patent 4,272,856, certain parameters with respect
to the load, i.e., weight, patient size and load footprint, are
matched to the plenum chamber area, otherwise the unit will not
work or works poorly. The co-applicant herein ascertained that
an air pallet plenum chamber upon pressurization tends to take
a shape resulting in lateral reduction of the plenum chamber air
film footprint. Since the patient°s body is movable and flexes,
this creates significant problems. Not only is such load not
rigid, but the top flexible sheet is not a rigid member and,
indeed nothing structurally is rigid. Further, only the torso
and head is supported by the plenum chamber, (i.e., jacked up),
and the rest of the body ( legs, arms, etc. ) simply drag along
with the air pallet once an air bearing or air film is created
by escape of air through the perforations within the thin,
WO 93/ 11062 PCT/ US91 /08660
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flexible bottom sheet. If the patient has a broken limb, this
is not a small problem, but a catastrophe.
Patient loading on the air pallet and removal from the air
pallet provides significant problems, as well as the ability to
create a patient mover having a size to fit the patient, the bed,
the portable gurney and a procedure table such as an operating
table.
These problems led initially to developments exemplified by
U.S. Patents 4,528,704 and 4,686,719. However, these
developments raised more questions than they provided answers.
The key to solving most of the problem areas seems to the
applicants to lie in the utilization of a rigid backing member,
but a rigid backing member make it more difficult to place the
patient on the patient mover. The patient has to be physically
log-rolled way over, and almost face down to one side so that the
rigid backing member is juxtapositioned to the patient, and the
patient is then rolled back over so that the patient ends up
supine on the patient mover. This procedure follows that of
placing the sheet under a patient when on a hospital bed, but
then a sheet can be folded in half and slid under the patient
without turning his body excessively to one side. Such is not
so for a patient mover having a rigid backing member.
Attempts were made at formulating a useful air chamber type
air pallet using a f lexi.ble pad to eliminate the rigid backing
member by or substituting an all-flexible sheet material
structure for such rigid backing member, Figures 4 and 5 of U.S.
Patent 4,528,704 amounted to an initial approach. Generally at
the same time, the applicants considered the separation of the
jacking action from that of creation of the frictionless air
film> ~ This pled to the development of stacked tubes, one
functioning as a pure jacking chamber, and the second as a
combined j asking chamber and plenum chamber . The result is a gas
pressurized jacking structure with improved load stability, in
which the same compressed air pressurizing the upper chamber
through a dynamic flowthrough arrangement, functions in passing
WO 93/ 11062 PCT/LJS91 /08660
through the pin hole perforations of the plenum chamber thin,
flexible bottom sheet, to create the air film. Such dynamic air
pallet is the subject of U.S. Patent 4,417,63.
In air chamber-type air pallet patient movers as exemplified
by Figures 4 and 5 of U.S. Patent 4,528,704, a phenomenon was
experienced as the result of air pressurization of the tubular
chambers formed by sealed sections of the upper two thin flexible
sheets, and the air pressurization of the plenum chamber
underlying all of the upper row of tubes commonly to the
intermediate thin, flexible sheet~of said row of tubes. The
entire unit took on a full vertical, circular cross-section and
attempted to approach a cylinder as seen in applicants' Figure 1,
which was termed "hot dogging". Such hot dogging was found to
lead to extreme air pallet instability, with any load on the air
pallet easily displaced. Applicants have determined that the
pressurization of such air chamber-type air pallet is quite
critical and a careful balance is required between inflation and
flotation. During hot dogging, the plenum chamber takes.on an
almost circular cross-section in a plane at right angles to the
longitudinal axis of the series of line joined tubes formed by
the top thin, flexible sheet 202, the intermediate thin, flexible
sheet 204 and the bottom thin, flexible sheet 206 of air
pallet 290 of the drawings. This structure conforms to Figure 4
of U.S. Patent 4,528,704. A plenum chamber 208 is formed between
the thin, flexible, intermediate sheet 204 and bottom sheet 206
and the sheet 206 has literally thousands of closely spaced pin
holes 210 through which air escapes from the plenum chamber to
form an air film or air bearing A between the thin, flexible
bottom sheet 206 and the generally rigid, planar surfaee 212.
Each-- of tie ' transverse seal lines 214 j pining the top and
intermediate sheets 202, 204, together forming individual
compressed air pressurizable chambers or tubes 216, function as
hinging areas between adj acent tubes . The result of such is high
instability for any load such as a patient's feet in contact with
the exterior of the top thin, flexible sheet 202. It is further
WO 9~/ i 1062 P~L.'H'/L~S91 /08660
m
obvious that the single large sectional area formed by the plenum
chamber 208 is without a means for controlling hot dogging and
is thus extremely susceptible to the instability problem.
- Further, in arriving at Figures 4 and 5 of U.S.
Patent 4,528,704, co-applicants hereof have attempted to form a
useful air chamber-type air pallet. Such is hampered by a
phenomenon resulting both in an instability problem and ur~~ier
severe conditions a loss or reduction in effective plenum chamber
air film or air bearing footprint area to the extent where the
air bearing cross-sectional area becomes too small to carry the
load, the load may roll off the upper flexible sheet support area
as the air pallet assumes a cylindrical shape and the air pallet
may ground out as it loses air bearing cross-sectional area or
a combination of all three adverse effects occur.
Where the plenum chamber P, Figure 2, is of a given width W
when flat and deflated, the tendency of such plenum cha: ~ :'r is
to have that width W reduced to W' the diameter of the tube when
full inflated, as seen by a comparison with Figure 3.
Another phenomenon which occurs utilizing the air
chamber-type air pallets of Figures 4 and 5 of U.S.
Patent 4,528,704 is a lack of rigidity of the air chamber
assembly defined by the tap thin, flexible sheet 202 and the
intermediate flexible sheet 204, as the result of air
pressurization of all of the chambers 216 of the row of tubes and
the air pressurization of the plenum chamber 208, which underlies
the tube array defined by thin, flexible sheets 202, 204. While
the walls of the individual chambers or tubes 216 are relatively
taut, upon air pressurization of the same, whether in the sealed
air pressure tubes such as the embodiment of Figure 4 of U. S.
Patent 4,5Z8,~704 or the flow-through tubes 80 of the Figure 5
embodiment of that patent, the line connections between abutting
s:.des of the parallel row tubes 216 permit tube sectioning lines
to act as hinges, and causing the unwanted hot dogging of the air
pallet 200, Figure 1. Further, wh~'~ the presence of a load such
as a patient and the weight thereof . depressing the upper surface
WO 93/ 11062 PCT/US91 /0660
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of the air pallet Figure 1 (corresponding to Figures 4 and 5 of
U.S. Patent 4,528,704) tends to resist the ballooning of the air
pallet, and enhance the stability of the load. However, such
structures inherently lack means for preventing significant
lateral shrinking of the plenum chamber.
In view of the lack of rigidity of the air chamber type air
pallets as illustrated in Figures 4 and 5 of U.S.
Patent 4,528,704, an investigation by the applicants of the
various causes for suppleness in contrast to desired rigidity ( in
view of the attempt to substitute an air chamber or air chambers
for the rigid planar backing member of the air pallet) led to the
determination that rigidity of any part of an air chamber type
air pallet can be achieved from solely two means, ( l ) varying the
air pressure within the various chambers of the air pallet (the
result of which tends to create ballooning, and the high air
pressure was found to be undesirable to the inherent ballooning
or tendency to balloon), and (2) employing a solid, unbendable
stiff upper sheet supporting the load, and for a point. load,
spreading that load over the complete surface of the unbendable
upper sheet. While the unbendable upper sheet was sufficient to
avoid ballooning, the desired rigidity can only come from the air
pressure within or f lowing through the various chambers of the
thin, flexible sheet structure.
Further, in operation of the air chamber type air pallets,
Figures 4 and 5 of U.S. Patent~4,528,7D4, the plenum chamber
being unsectionalized and linked solely to the tubular arrays at
opposite ends and along opposite sides of the air pallet, such
structure either creates, or enhances suppleness of the structure
which prevents~the row of tubes of the air pallet from acting as
a substitute~for the rigid backing member normally employed in
such air pallet structures.
It is, therefore, a primary object of the present invention
to provide an improved air chamber type air pallet of the patient
mover or patient positioner type which is lightweight and which
may take the form of a °°soft pad" or "hard pad" type having the
WO 93/ 1 1062 PCT/US91 /08660
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facility for the creation of a semi-rigid or generally rigid
backing member, which eliminates the need for the inclusion of
a rigid or semi-rigid sheet as a load backing member, which
permits the patient to be physically moved in a relatively
frictionless manner, which is formed wholly of,thin flexible film
or sheet material, which includes a degassing feature upon point
pressure application to inherently induce therapy to the patient
supported by the same, which is highly stable in operation, which
readily holds the patient in a supine horizontal position, which
tends to prevent spinal flexure, which may function as a body
wrap to restrain the patient laterally and vertically, and which
may be readily folded and transported upon depressurization of
the air pressurized chambers formed by plural, locally sealed
thin flexible sheets.
It is a further object of the present invention to provide
improved, soft pad or hard pad, air chamber type air bearing
patient movers which may be formed totally of thin flexible sheet
material in multiple layer form with selective sealed pressurized
air containment and/or flow through chambers by localized thermal
bonded or sewn seal lines between respective sheets of a stacked
sheet array, which may selectively include portions of the soft
pad or hard pad air pallet with controlled rigidification for
support of the patient with assured comfort, which facilitates
patient positioning, which correlates the air bearing footprint
to that of mass distribution of the load on the patient mover,
which is particularly useful as a patient mover, which utilize
a series of side-to-side linked hollow tubes subject to constant
pressurized air application or continuous compressed air flow as
single or plural stacked arrays of side-to-side linked hollow
tubes defining a semi-rigid backing member for the air pallet,
which air pressurization can be varied or maintained below that
which would induce patient capillary closure, which facilitates
lubrication of the patient body surface during support of the
patient, which prevents lateral shrinkage of the portion of the
compressed air plenum chamber forming the air film through the
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bottom thin flexible sheet perforated portion to prevent
bottoming out of the load on the air pallet, which forms an air
mattress which may be selectively rendered highly rigid as a
"hard pad" or highly supple as a "soft pad" , depending upon need,
without removal of the patient therefrom, and which has
application universally from use at the accident scene, to
emergency transport from the scene of the accident to the
hospital or other treatment facility, transport throughout the
hospital including to and from the operating room, and as an air
mattress with minimum trauma to the patient at all times.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a vertical sectional view of an air pallet of
the prior art showing the effect of unwanted hot dogging under
air pressurization of a single row of linked tubes, and the
single plenum chamber underlying the same.
Figure 2 is a sectional view of a single tube prior to air
pressurization thereof.
Figure 3 is a sectional view of the tube of Figure 2
illustrating lateral shrinkage thereof upon air pressurization.
Figure 4 is a schematic vertical sectional view of an air
chamber-type patient mover air pallet formed of two thin,
flexible sheets, forming a preferred embodiment of the present
invention, prior to inflation.
Figure 5 is a vertical sectional view of the air pallet of
Figure 4, under air pressurization.
Figure 6 is an end view of the air pallet of Figures 4 and 5
during placement partially beneath the patient and under air
pressurization.
Figure 7 is a similar end view to that of Figure 6 during
initiation :of~ patient transfer, partially supporting the patient.
Figure 8 is a further end view, similar to that of Figures 6
and 7, with the patient fully supported by the air pallet.
Figure 9 is a schematic, vertical sectional view,
illustrating the anti-shrink effect resulting from the
utilization of small diameter side-to-side linked tubes of the
WO 93/ 11062 P~"T/US91 /08660
two flexible sheet air chamber-type patient mover air pallet of
' Figures 4 and 5.
Figure 10 is a schematic top plan view of a two-sheet air
'. chamber-type patient mover air pallet, forming a further
embodiment of the invention.
Figure 11 is a schematic top plan view of yet another
embodiment of the two-sheet, air chamber-type patient mover air
pallet of this invention.
Figure 12 is a schematic top plan view of a further
embodiment of the invention for a simplified air chamber-type
patient mover air pallet formed of a series of longitudinally
spaced tubular air chambers of varying diameter.
Figure 13 is a schematic top plan view of a further
embodiment of a two-sheet air chamber-type patient mover air
pallet of the present invention.
Figure 14 is a schematic top plan view of a simple two-sheet
flexible film air chamber-type patient mover air pallet forming
yet another embodiment of the present invention. .
Figure 15 is a schematic representation, in sectional form,
of a single chamber air pallet contrasted to that formed by a
series of linked tubes and illustrating the significant increase
in tangential air film footprint for the air pallet formed of a
series of small diameter side-to-side linked tubes, to that of
the single chamber-type air pallet.
Figure 16 is an X-Y coordinate plot of the operating
parameters associated with the air chamber-type patient mover air
pallets forming various embodiments of the present invention.
Figure 17 is a schematic top plan view of a further
w v~o-sheet flexible film air chamber-type patient mover air pallet
the ~resen~t invention.
Figure Z8 is a schematic, top plan view of a modified form
of air chamber-type patient mover air pallet of the present
invention.
Figure 19 is a schematic vertical sectional view of a
modified form, simple two-sheet flexible film air chamber-type
WO 93/11062 PCT/L~S9110$660
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patient mover air pallet of the present invention prior to air
pressurization of the tubular chambers thereof.
Figure 20 is a schematic vertical sectional view of the air
pallet of Figure 19 under air pressurization, taking a "cradle'°
position about a patient thereon and conforming to a chute
supporting the air pallet and between which an air film is
developed.
Figure 21 is a schematic vertical sectional view, on an
enlarged scale, of the air pallet of Figure 4, illustrating the
effect of the load and the preferred placement of the pin hole
perforations within the thin, flexible bottom sheet of that
structure.
Figure 22 is a similar view to that of Figure 21,
illustrating the flattening of the tangential contact portion of
the tubes with the underlying support surface and the resultant
air bearing created thereby.
Figure 23 is a schematic vertical sectional view of a
flexible film air chamber--type patient mover air pallet, forming
yet another embodiment of the present invention.
Figure 24 is a schematic vertical sectional view of an
alternate form of three-sheet, air chamber-type patient mover air
pallet of the present invention.
Figure 25 is a schematic vertical sectional view of yet a
further embodiment of the invention in the form of a three-sheet,
flexible film air chamber-type patient mover air pallet with an
air reservoir feature for preventing complete collapse of any one
of the segmental plenurn chambers incorporated therein.
Figure 26 is a top plan view of a four-sheet, flexible film
air chamber~type patient mover air pallet forming a preferred
embodiment :of~ the present invention.
Figure 27 is a top plan view of the top, thin, flexible
sheet of the air pallet of Figure 26.
Figure 28 is a top plan view of the first intermediate, thin
flexible sheet of the air pallet of Figure 26.
WO 93/11062
PC'f/US91 /0660
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17
Figure 29 is a top plan view of the second intermediate,
thin flexible sheet of the air pallet of Figure 26.
Figure 30 is a top plan view of the bottom, thin flexible
sheet of the air pallet of Figure 26.
Figure 31 is a schematic, vertical sectional view of the
assembly of the four sheets for the air pallet of Figure 26 and
the longitudinal seal lines selectively joining the same to form
air tubes or air chambers in multiple linked tube and linked row
fashion for the air pallet of Figure 26.
Figure 32 is a perspective view, partially cut away, of the
air pallet of Figure 26 after inflation, and illustrating in
dotted lines a fifth, thin, flexible sheet to form a second air
bearing at the top of the air pallet.
Figure 32a is a perspective view, partially cut away, of the
air pallet of Figure 32, modified to form a flow through single
air source type air pallet.
Figure 33 is a top plan view of a four-sheet, thin flexible
film, air chamber--type patient mover air pallet forming . yet a
further embodiment of the present invention.
Figure 34 is a top plan view of a (first intermediate, thin,
flexible sheet of the air pallet of Figure 33.
Figure 35 is a top plan view of one of dual second
intermediate, thin flexible sheets of the air pallet of
Figure 33.
Figure 36 is a top plan view of a bottom thin, flexible
sheet of the air pallet of Figure 33.
Figure 37 is a schematic, vertical sectional view of the air
pallet of Figure 33, illustrating the longitudinal seal line
between the thin, flexible sheets of that air pallet, and the
formation of individual air tubes or chambers thereof.
Figure 38 is a perspective view, partially broken away, of
the air pallet of Figure 33 under air pressurization and
illustrating the extent of hot. dogging of that air pallet.
WO 93/11062 PCt'/US9110~660
~a'~.'~ ~'~~
la
Figure 39 is a schematic, vertical sectional view of a
modified air chamber-type patient mover air pallet of Figure 26,
forming yet a further embodiment of the invention.
Figure 40 is a plan view of an open frame forming a lateral
anti-shrink element employable in the alternative to the rigid
sheet of the embodiment of Figure 39.
Figure 41 is a schematic,~vertical sectional view of yet a
further f lexible sheet, air chamber-type patient mover air pallet
of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED ENIBODIMENfiS
The present invention in the various embodiments described
in detail hereinafter takes into account the parameters discussed
within the Background 4f The Invention section of this
specification, and from the need to provide effective air
chamber-type air pallet patient movers permitting the loading of
the patient thereon and the unloading of that patient therefrom
without the trauma and discomfort caused by the attendent log
rolling of the patient to accomplish those actions. The flexible
backing chamber air pallet involves, in addition to jacking,
pillowing and ballooning other critical phenomenon and operating
parameters which must be controlled. The air pallets of the
invention additionally require means for preventing the hot
dogging phenomenon discussed above. The applicants have
determined that the existence of singular or multiple large
sectional areas which cause a major portion or the totality of
the air pallet, with the singular chamber or multiple linked
chambers inflated, to take a true circular cross-sectional
configuration results in instability to the load and trauma to
the patient.-,Keyed to the field of patient transfer, the present
inventibn in~the several embodiments as set forth hereinafter,
provides a solution to the problem of placement of a patient onto
an air chamber-type air pallet patient mover, which eliminates
undesirable lag rolling, and possibility of severe spinal cord
injury to the patient.
WO 93/ 11062 PCT/US91 /08660
19
Referring to Figures 4 and 5, one embodiment of an air
chamber-type patient mover air pallet 310 is formed of two thin,
flexible sheets 302 and 304 which are sewn together about all
four edges or heat sealed via spaced longitudinally extending
seal lines 308 to form individual side-by~~ic~e parallel
chambers 306. The individual chambers or tubes 306 which tend
as per Figure 5 to take a circular cross-section when air
pressurized via a soLrce of compressed air indicated by arrow 314
applied to the chambers, are, in this case for example, connected
in series through an air inlet tube 312. To create an air
bearing A beneath the bottom thin, flexible sheet 304 thousands
of pin hole-type perforations 316 are provided within the bottom
sheet 304, in this case preferably limited to the central area
of respective tubes or chambers 306. The two-piece patient mover
air pallet consists, therefore, of an imperforate upper, thin
flexible sheet 302 attached at intervals to a lower, thin
flexible sheet 304 with a plurality of perforations 316 within
the bottom thin, flexible sheet' and an air inlet tube 312
communicating to all chambers or tubes 306. The patient P is
moved onto the patient mover air pallet by folding the air
pallet 310 about its longitudinal center line, Figure 6 defined
in this case by the middle longitudinal seal line 308, prior to
air pressurization of, chambers 306 with the patient lying in the
supine position. By wedging the folded two-piece air pallet with
the perforations 316 facing each other, the folded, deflated
patient mover air pallet 3~.0 can be placed under the patient much
in the same manner that a folded sheet can be placed under a
patient when remaking the bed without moving the patient from the
hospital bed. Such may be accomplished with relatively little
moY~ment of the patient.
Upon air pressurization of plenum chambers 306, the patient
is jacked to some extent, an air bearing is created at A,
Figure 6, between the folded over halves of the patient mover air
pallet 31.0, and the patient P is caused to move up onto the
imperforate upper thin, flexible sheet 302, Figures 6, 7. The
WO 93/ i 1062 PCT/IJS91 /08660
r
2C
patient can then be moved back onto a gurney, backboard B or the
like, with or without environmental control sheets, Figures 7, 8
as support equipment, and as needed or desired.
By gently inf lating the patient mover air pallet 310 , . it may
be pulled by one transverse edge across itself with frictionless
movement resulting from the application of pressurized air to the
interior of the chambers or tubes 306 which function as plenum
chambers . The air bearing A is created as a result of compressed
air discharging from the plenum chamber through the pin hole
perforations 316 which open unrestrictedly interiorly and
exteriorly of the patient mover air pallet 310. At the same time
by jacking, the patient°s body is lifted evenly. The air
pallet 310 includes means for controlling pillowing of the air
pallet plenum chambers formed by the linked tubes, and the
patient is eventually totally supported by the patient mover air
pallet. The patient may then travel across an environmentally
controlled sheet onto backboard B.
Referring next to Fic_~ure 9, and comparing that figure to the
result of inf lation of a f lat, def lated single chamber body,
Figures 2 and 3, the applicants have ascertained one of the
operating parameters and key aspects of the patient mover air
pallets of the present invention. Where the desired lateral
width W, Figure 2, of an air pallet is to be maintained, the air
chamber pallet is composed of or built up of many smaller
diameter sectional membranes linked together resulting in a
significant reduction in lateral width, or shrinkage . Width W' ' ,
after air pressurization of chambers 306 of the patient mover air
pallet 310 of Figure 4 , is signif icantly larger than the width W'
of the single inflated chamber 220, Figure 3, whose diameter D
when fully inflated is approximately two-thirds of its flat,
deflated width W, Figure 2. Nate that the diameter D° of each
chamber 306 in Figure 9 is significantly smaller than the
diameter D of the single chamber 220 structure when inflated,
Figure 3.
WO 93/11062 PCT/US91/08660
21
In terms of desired flow paths for compressed air under
pressure moving through the various tubes or tube sections of a
two-ply air pallet formed solely of two thin, flexible sheet
material heat sealed in localized, linear fashion,, Figures .10, 11
and 12 are exemplary of seal lines forming parallel f low paths
from a single air inlet. In Figure 10 air pallet 410 has
compressed air source 414 feeding air via air inlet 412 to
parallel tube plenum chambers or sections 416, each linked by
flow reverse turns 420 defined by seal lines 408.
In Figure 11 a singular f low path 520 starting from the
inlet 512, of modified spiral form by seal lines 508 between two
flexible sheets forms a unitary plenum chamber air pallet 510.
In Figure 12, the two sheet air pallet 610 uses a plurality of
short length parallel unevenly spaced seal lines 608 transverse
to the longitudinal extent of the air pallet 610, permits
parallel flow paths to open from right angle flows along opposite
longitudinal edges of the air Ballet which longitudinal paths
form air flow manifolds 622 from inlet 612 from air source 614.
The tubes or plenum chambers 616 which run transversely, and are
of varying width, meet the specific mass concentration areas of
the load supported thereby (human body).
Figures 13 and 14 show additional embodiments of the present
invention, specifically directed to two-sheet air chamber-type
patient mover air pallets, as at 710 and 810 respectively. In
Figure 13, compressed air, as indicated by arrow 714, enters
inlet 712 for parallel f low through spiral-like dual plenum
chambers to laterally opposite sides of the air pallet 710 as
defined by seal lines 708 constituted by vertical and horizontal
ribbing of the chambers defined thereby. The distance between
parallel longitudinally extending ribbing, i.e., seal lines, can
be altered, graded, enlarged, or decreased to control lift, load
support, cradling, etc. of the patient to meet the environment
needs for the patient mover air pallet.
It is apparent that by creating a number of small diameter
chambers or tubes in a single linked row in accordance with the
WO 93/11062 PCTII_JS91/08660
..,;
22
superpositioning of air pallet 310 , Figure 4 , on a large circle C
to form a chamber 220 equivalent to that of Figure 3, D' is many
times smaller than the original D associated with chamber 220.
The hot dogging of the resulting structure is .considerably
reduced and provides effective control in supporting a load
thereon, particularly a patient P. Upon close examination, the
applicants have determined another change which takes place to
the bearing surface of a cylindrically-shaped object such as a
plenum chamber bearing on the underlying fixed support surface
such as surface 311 where that object is formed of a thin,
f lexible sheet. Even without loading, the large circle C assumed
to be the cross-section of an elongated tube, air pressurized and
formed of thin, flexible sheet, will have an appropriate
footprint when flattened against the underlying fixed support
surface 311 spreading from its contact point of tangency at .the
center of the circle C. In Figure 15, the large circle C
footprint occupies a width or dimension X which is significantly
smaller than the potential tangential air film footprint X', as
represented by the same extreme tangential contact point for the
outermost small diameter D' tubes of the patient mover air
pallet 310 superimposed on the large circle C, Figure 15. By
dividing the circular circumference so as to form a multiplicity
of smaller circles of a diameter D' as exemplified by the first
embodiment of the present invention, Figure 4, i.e., patient
mover air pallet 310, the combined circumference of the smaller
tubes still has the same circumference as the big circle C, but
the potential footprint area of the load ~ can be signif icantly
larger. The applicants have ascertained that not only is there
control of the hot dogging tendency of such air chamber-type
patient mover air pallets, but the present invention maximizes
the load footprint area and indirectly the perforation area of
the individual plenum chambers defined by the separate tubes or
chambers 306, providing the air film or air bearing A. The
control is therefore of the shrink of the load footprint area in
contact with the supporting surface of the plenum chamber or
WO 93/11062 PCf/TJS91/08660
~ .,e ~, ~ ~~ ,-.~ --
l ; ;i ;t~ .
i~ .~~ Akn ~ '. 4.~~' iJ
23
chambers, which in turn provides the ability of the air pallet
to support the load P. In addition, Figure 15 represents a
further phenomenon or operating parameter ascertained by the
applicants. Tnstead of the large volumetric area.of,the lower
half of the circle C (beneath the superimposed'air pallet 310)
consisting of laterally edge-abutting tubes or chambers 306, such
is minimized (essentially eliminated), the result of which is
stabilization of the air pallet against hot dogging.
Additionally, as will be seen hereinafter, the individual
tubes 306, due to the presence of the load P and on the basis
that the chambers or tubes 306 constitute plenum chambers through
which air escapes via pin holes 316 to form the air bearing or
air film A between the thin, flexible bottom sheet portions of
the plenum chambers gearing the perforations, flatten to form
small footprint areas corresponding to the large circle C
footprint X of Figure 15. The tubes 306 perform the necessary
pillowing control and anti-ballooning. The applicants have
additionally determined that by limiting the area of, the
thousands of pin hole-type perforations to that surface area of
each plenum chamber or tube 306 which is flat and in near contact
with the planar rigid support surface 311, essentially only the
flat surface area having perforations 316, the footprint of the
air film for the patient mover air pallet 310 conforms to that
of the load P .
Figure 16 is a rendition of an X-Y coordinate structure and
depiction of what occurs in Figure 15, evidencing the operating
parameters of a single, very large plenum chamber C in contrast
to an air pallet formed of multiple linked tubes of two-sheet
form 'constituting plenum chambers and functioning to jack the
load, support that load, and to produce the underlying air
film A, Figure 5. The plenum chamber air film extends along the
X axis of the plot, with the plot illustrating vertically upward
from that X axis, in respective order of magnitude, jacking,
pillowing, ballooning and hot dogging control factors or
parameters of the air chamber-type patient mover air pallets of
WO 93/11062 p~T/LJS91/08560
v
x ~~ ,~_ ~
4 % ~ tW ~'' _.
:w
24
the present invention. As one phenomenon reduces, one or more
increase. The applicants° structures of the present invention
control the changes to maximize the air film footprint with the
air chamber or chambers preferably taking the form of,elongated
cross-sectional rectangles rather than being of elongated hot dog
shape, i.e., circle C, Figure l5.
The aspects discussed above, partieulaxly with respect to
Figures 15 and 16 are keyed to the necessity for reduction in
lateral shrink and maximum retention of the air film surface with
minimal loss of the air bearing A developed between the thin,
flexible bottom sheet of the air pallet and the underlying rigid
planar support surf ace 311.
In that respect, it is apparent that shrink does not occur
along the axis of a tubular membrane, but perpendicular to that
axis. Mathematically shrink measures out to be about one-third
or a function of n. From Figures 10-14 the control of the
lateral shrink, parallel to the developed air film A and its
structural orientation with respect to the position of the load
on an air pallet is the key to the air pallet°s performance. An
air pallet formed of two thin, flexible sheets locally heat
sealed to each other for movement of a supine body permits the
basic unit to have a series of tubes running in the same
3irection, parallel to the fold line. The size of the tube
diameter determines the height of the inflated unit and is
preferably kept to a relatively small value. By using a
combination of tubes, some perpendicular to others, control of
shrink occurs in both directions, and sueh tube arrangement
performs an anti-shrink action.
Figure l7 illustrates schematically, a two-sheet air pallet
similar to that shown in Figure 4, using like numerals for like
elements, with tubes 306 forming plenum chambers defined by seal
lines 308, all being parallel and in line with f low entering
inlet 312 from a compressed air source 324 f lowing transversely
across the air pallet 310 to the side opposite the inlet 312 and
WO 93/ 11062 P~C_'T/LJS91 /08b60
" . :.
with parallel air f lows through the individual tubes 306 of the
tube array.
Figure 18 illustrates an air chamber-type patient mover air
pallet 910 of simple two flexible sheet form with.a single air
inlet 912 receiving compressed air from source X14 and with flow
occurring within tubes 906 along opposite longitudinal sides,
while tubes 922 extend transversely parallel to each other, from
one longitudinal end to the other, between longitudinally
extending t .es 906 to opposite sides thereof, all receiving
compressed air from a single source 914. In all of the
embod=..rents of the invention using two thin flexible sheets, the
multi~:..~~ tubes constitute plenum chambers described above and the
thin flexible bottom sheet, in each instance includes a pattern
of thousands of closely spaced pin hole perforations which are
not shown for simpli'~ication of the views.
Variations occur by separation of flows into multiple
chambers of serpentine or spiral form to prevent the multiple
thin, flexible sheet structure from reaching its free cylindrical
shape in contrast to that of a singular tubular unit.
Thus, various combinations of fabrication and joining of two
sheets of simple two-sheet air chamber-type patient mover air
pallets may be employed, accomplishing different end results, but
all based on the basic principles discussed in the creation of
the air pallet 310, Figure 9.
Reference to Figures 19 and 20 show a modification of the
basic two-sheet air pallet 310 of Figure 4. In this case, the
air pallet 310' otherwise corresponding to that of Figure 4 is
again formed of a thin flexible top sheet 302' and a thin,
flexible bottom sheet 304' being heat sealed or otherwise bonded
or sewn along four sides and longitudinal lines 308' to form
individual tubes or chambers 306'. However, the lateral distance
between lines 308' of attachment for the lower sheet 304' is much
larger than that for the upper sheet 302' so that upon inflation,
the air pallet 310' tends to curl upwardly into a U-shaped form,
see Figure 20, and thus cradle a patient P. With air
WO 93/ 11062 PCT/LJS91 /08660
w,
N
t A ~~. l'~,s~ ~t3
26
pressurization of the individual plenum chambers 306' the
inverted arch tends to adversely alter the air bearing A created
between the thin, flexible bottom sheet 304' and the underlying
rigid planar support surface 311' as air exits ,from pin
holes 316'.
A U-shaped chute 311' a, shown in dotted lines maintains the
air bearing or air film A if curved corresponding to the inverted
arch, Figure 20. If, as shown, the lower sheet has excess
material accumulated between the joined lines compared to the
upper sheet , then upon inf lation of the chambers a '°
cradling°'
phenomenon takes place. To the contrary, if more slack is
accumulated between the upper sheet seal lines then the air
pallet will arch upwardly.
As touched on briefly above, turning to Figure 21, where the
simple two-sheet air chamber-type patient mover air pallet 310
takes the form of plenum chamber tubes 306 which are joined by
longitudinal seal lines 308 and under air pressurization, the
placement of the load (patient) P on the air pallet causes a
flattening to occur to the circular cross-section tubes, both at
the top and at the bottom. Where the cylindrical tubular members
face the underlying ffixed support surf ace 311, each will tend to
flatten out over a limited surface area of the circular arc.
Depending upon the weight of the load P and the relative air
pressure inside the tubes, the extent of flattening will vary.
The greater the surface area of the thin, flexible bottom sheet
in near contact with the underlying support surface, the greater
the lift and area for air film development through the
perforations 316 facing the underlying support surface and the
greater the tendency of the air pallet to function at a lower
operating air pressure. Additionally, as per Figure 22, there
is less longitudinal channel voids V to allow the air to escape
along the axis for the tubular joints defined by the seal
lines 308 without providing any lift or developed air film A.
Applicants have determined that by limiting the area of
perforations to that area normally flattened within the thin,
WO 93/11062 PCT/US91/086b0
w
27
flexible bottom sheet 304, as at 318 for each of the tubes or
plenum chambers 306, the effective footprint of the developed air
bearing or air film A remains substantially equal to that of the
footprint of the load P (patient) supported .by, the air
pallet 310. Applicants have determined that ~y using a great
number of small diameter, pin hole-type perforations, i.e.,
literally thousands of perforations, there is more effective lift
from the escaping air through the perforations 316. To obtain
maximum lift, using minimum air pressure it is desirable to have
as large a tangential f1~- -.rea as possible for each of the
tubes 306 along the fixed p~a:,ar support surface 311, to obtain
maximum lift. If the perfora;:ed area is limited to the flat area
for each of the tubes 306, then the effective surface area of the
developed air film, i.e., the footprint of the air film is
maintained approximately equal to that of the load P.
From the discussion above and as it relates to the
embodiments of the invention described in detail above, and those
described here~.aafter, it is obvious that a large singular
tubular structure is not an effective way to either jack a load,
or maintain an air film large enough to move the load while
providing stabilization of the load riding on an air pallet
particularly one of the air chamber-type. By utilizing a series
of small diameter tubes as a lateral array with those tubes
functioning as plenum chambers, by restricting the supporting
surface of the plenum chamber which is flattened in contact with
the underlying relatively fixed planar support surface, and by
limiting the area of perforations to such area, maximum lift is
achieved and maximum film lubr~.cation area for the load thereby
resulting in the largest overall efficiency for an air pallet
operating under the least volume and pressure of air input to
that plenum chamber for jacking the load, for controlling
pillowing, for creation of the air bearing and for stabilization
of the load, with restricted air loss between the plenum chambers
creating the developed air film.
WO 93/ 11 Ob2 PCT/ US91 /0660
~t~J ~~~'1 ~~
An extant operating parameter which is critical to
successful operation of air chamber-type patient mover air
pallets (and to such air pallets employed generally in material
handling) involves the rigidity of the structure .handling the '
patient or other load. Rigidity can only be ac~~ieved from two
means as discussed previously; the air pressure that develops
pillowing and which leads to ballooning and the weight of the
load itself.
The present invention also resides in the appreciation that
rigidity must come from the pressurized air ffilling or flowing
into and through a flexible multiple tube structure and is
accomplished by chambering or tubular configurations which are
formed of or include means which provide lateral rigidity and
additionally resist the downward force created by the load on the
top of the air pallet. Due to the possibility of induced trauma
to the patient during patient moving, these needs must be
accomplished while avoiding point contact between the patient and
a rigid surface, the result of developed bending moment while
utilizing assemblies that form semi-rigid or near rigid members
when air pressurized.
The development of operable two-sheet, soft air chamber-type
patient mover air pallets in the form shown in Figure 4 and in
accordance with variations thereof, through Figure 22 have led
to successful creation of such air pallets utilizing the two
thin, flexible sheets to form a single row of chambers or tubes
which are physically linked or joined, and which include means
defined by a third sheet or its equivalent to form semi-rigid
backing chambers as the equivalent for the rigid sheet or
semi-rigid sheet of the earlier air pallets discussed in the
Background Of The Invention portion of this specification. In
Figure 23, an air chamber-type patient mover air pallet,
indicated generally at 1010 is formed of a thin, flexible upper
or top sheet 1022 physically separate from a thin, flexible
bottom sheet 1004, but linked by vertical imperforate
stringers 1002 which are sealed or otherwise joined at opposite
WO 93/ 11062 PCT/ US91 /08660
29
ends by seal lines 1008 to sheets 1002, 1004 to thereby define
linked plenum chambers or plenum chamber sections 1006 open to
each other at the ends or otherwise. Sheet 1004 has
perforations 1016 through which compressed air from source 1014
after entering the plenum chambers through the plenum
chamber 1006 to the extreme right and by flowing therebetween
seeks escape through the pin hcle-type perforations 1016 to form
air bearing or air film A bet~.reen the bottom thin, flexible
sheet 1004 and the generally _::~ed underlying support planar
surface 1011. Stringers 1022 corm vertical walls which are
equally pressured on opposite sides to render those stringers or
walls 1022 taut as the result of air pressurization. Such
stringers or walls 1022 are required at laterally spaced
locations across the full width of the plenum chamber or at least
the area of perforations forming the underlying air bearing A.
Contrary to the embodiment of Figure 4, not only is the air
pallet formed of additional members other than the top thin,
flexible sheet and the bottom thin, flexible sheet, but the
junctures between the sheets do not form "hinges°' as occurs for
seal lines 30~ joining the top and bottom sheets 302, 304 of the
embodiment of 310, Figure 4. To the contrary, by utilizing
stringers or vertical walls 102 which are subject to air
pressurization on opposite sides, such members as a result of
inflation function as a "I" beams. The same has been found true
where air pallets of the air chamber-type are formed where the
defined chambers are commonly not plenum chambers through which
air escapes via the pin hole perforations 1016 to define the air
bearing A, but are jacking chambers for jacking the load and
constitute an array above the plenum chamber and separate
therefrom. The present invention is therefore to a significant
extent directed to air chamber-type air pallets, where multiple
tubes or chambers are formed of the thin, flexible sheet
material, with the tubes being joined at two points which are
some degrees apart on the circumferences of the tubes.
WO 93/11062 PCT/US91/08660
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The applicants have determined that when two tubes are
attached at a single point (a line over their length) and then
inflated they readily bend around the point of attachment with
that point of attachment, or line of attachment.acting as a
linear hinge. To the contrary, tubes which are~attached at two
points, particularly in the order of 90° apart on their
circumference, when inflated, will form a rigid member between
the attachment area, i.e., a co~ranon wall which resists hinging
and which functions as an I-beam.
In accordance with the embodiment of Figure 23, which in all
other respects is similar to the embodiment of Figure 4, where
many tubes are fastened side-by-side over an extended width, a
rigid air platform is created by the tubes constituting plenum
chambers and developing the air film A. Similarly, tubes
fastened side-to-side over a circumferential extent of a number
of degrees will support a load and jack the load, irrespective
of whether:='they are functioning as plenum chambers bearing
perforations=~'to create the underlying air bearing or mere~.y air
backing chambers.
Turning next to Figure 24, a further embodiment of the
invention is indicated generally at 1110. In this embodiment,
which again is a variation of the embodiment of Figure 4, the air
pallet 1110 is formed of three separate, thin, flexible sheets,
a thin, flexible top sheet 1102, a thin, flexible bottom
sheet 1104 bearing areas of pin hole type perforations 1116 which
are closely spaced and in accordance with the prior embodiments,
and a thin, flexible intermediate sheet 1122. The intermediate
sheet bears a number of holes or air passage ports 1124,
permitting the air to move from chamber to chamber. The thin,
flexible bottom sheet 1104 is heat sealed transversely only at
opposite side edges, as at 1126, to the top sheet 1102. The
interposed intermediate sheet 1122 is heat sealed along
longitudinal lines as at 1128, alternately to the top and bottom
sheets. Thereby, the top thin, flexible sheet 1102 and the
intermediate thin, flexible sheet 1122 form an upper row of
wo 93i ~ ~ o6z Pcrivs9a sog~so
31
tubular chambers 1130, which alternate with and are laterally
offset from a lower row of tubular chambers 1132 formed by heat
sealing intermediate thin, flexible sheet 1122 and bottom
sheet 1104. The upper row chambers 1130 are bacl~ing chambers or
j acking chambers since they function to j ack the load and act
similar to the generally rigid backing member of U.S. Patent
3,948,344 to support the load, and the lower row chambers 1132
are plenum chambers with the thin, flexible bottom sheet being
perforated at 1116 for the three adjacent lower row chambers 1132
underlying the load P. In the basic structure shown in Figure 24
an air inlet tube 1112 receives compressed air from a source
indicated by the arrow 1114 with this air ffirst passing through
one of the upper row chambers 1130 and then entering the
laterally adjacent lower row chamber 1132, in alternating
sequence rendering a portion of the thin, f lexi.ble intermediate
sheet 1122 rigid, i . e. , like an I-beam. As a result, these tubes
do not take a circular or oval configuration, but, rather, a
triangular cross-sectional configuration. As will be seen, the
lines of attachment for the thin, flexible bottom sheet with
respect to the upper row of chamber~'1130 are at spaced
transverse positions deffined by seal lines 1128, uniformly over
the transverse width of the plenum chamber, providing the desired
rigidity to the structure while simultaneously limiting the
lateral shrinkage of the developed air f film A relative to the
footprint of the load P (patient). Additionally, the air pallet
of Figure 24, due to the lateral offsetting. of the tubular
chambers 1130, 1132, insures, that irrespective of deflation of
any one of these chambers for either the top row or bottom row,
the ~iatient P will not ground out against the underlying
generally rigid planar support surface 1111. Thus, no point
contact occurs between the.patient with resulting trauma and the
tendency to create bed sores. Additionally, the upper row of
chambers 1130 which do not function as plenum chambers,
constitute a row of thin, flexible sheet material backing
chambers of generally rigid form as a substitute for the rigid
WO 93/11062 PCT/US91/08660
o~ ~,
c~ .~~ ;~ ~ r~,~ 3
. w w
32
backing member employed in a significant number of air pallets
developed by one or more of the applicants herein, both in the
area of material moving and more specifically the patient mover
field. . .
Referring next to Figure 25, an air ~ pallet 1210 is
illustrated as supporting a load P as a further modification of
the basic air chamber-type patient mover air pallet formed by
three thin, flexible sheets, an upper or top thin, flexible
sheet 1202, a bottom thin, flexible sheet 1204 and an
intermediate thin, flexible sheet 1222. The upper and
intermediate sheets form backing chambers 1230. The intermediate
thin, flexible sheet 1222 and the bottom thin, flexible
sheet 1204 form a series of separate plenum chambers 1236 when
air pressurized from a source of compressed air as at 1214
entering inlet tube 1212 to one of the upper chambers 1230.
Suitable ports are provided as indicated at 1234 for
communicating the chambers and permitting air f low to pressurize
the upper row chambers and to enter the plenum chambers of the
lower row, pressurize the same, and exit through the thousands
of pin hole-like perforations 1216 within the thin, flexible
bottom sheet 1204. An air film A is developed between the bottom
thin, flexible sheet 1204 and the generally rigid support
surface 1211 underlying the air pallet.
There are two aspects to this embodiment which are
important. First, it is seen that the thin, flexible bottom
sheet 1204 and the thin, flexible top sheet 1202 are joined
commonly to the thin, flexible intermediate sheet 1222 at uniform
locations transversely across its width, as by seal lines 1238.
Secondly, them is sufficient slack within the thin, flexible
bottom sheet 1204 to provide plenum chambers 1236 of sufficient
volume or reservoir of air to insure adequate pressurization for
the passage of the air pallet over irregular surfaces or narrow
voids without bottoming, while providing an anti-shrink
construction via the common walls of the upper row of
chambers 1230. It is noted that some of the ports 1234 extend
. a , . . , :....,. -.. ~: . . .. .,_ ; :. .
WO 93/ 11062 1'Cf/U591 /08bb0
~J~
33
through the common vertical walls joining adjacent upper row
backing chambers 1230. The slack constitutes additionally the
pillowing means for controlling the jacking, along with the thin,
flexible sheet material defining the upper row o~ Chambers which
function to jack the load and to form the equivalent of a rigid
backing member, i.e., a series of backing chambers 1230.
Referring to Figures 26 through 38 inclusive, a further
embodiment of constant pressure sealed chamber, hard pad air
pallet, indicated generally at 10 is shown, being utilized,
preferably as a patient mover. It is formed by superpositioning
four thin flexible sheets of plastic film or a woven plastic
impregnated fabric material of rectangular form in a stacked
array, and thermal bonding the sheets together about the lateral
edges thereof with the exception of at least one air input
opening between the third and fourth sheets to permit air
pressurization of a plenum chamber defined by the third and
fourth sheets of the stacked array. The top or first thin
flexible sheet indicated generally at 12 overlies in order, a
second sheet indicated generally at 14, a third sheet indicated
generally at 16, and a fourth, bottom sheet indicated generally
at 18. As evidenced in Figure 31, which is a schematic
representation in which the sheets are vertically separated from
each other, the dotted vertical lines denote seal lines in which
the thin flexible sheets 12, 14, 16 and 18 are locally sealed to
each other along elongated parallel lines extending from one,
foot end 20 of the air pallet 10 to the other, head end 22,
Figure 26. Sheets 12, 14, 16 and 18 of rectangular plan
configuration are all of the same length but only sheets 12, 16
and 18 are of the same width. Intermediate sheet 14 may be
somewhat narrower for purposes which will be ap~3rent
hereinafter . In creating the assembly, the purpose of st::;~king
is to form individual sealed chambers or tubes which axtend
longitudinally from one end 20 towards the other 22. The bottom
sheet 18 includes a rectangular perforated area indicated
generally at 24 being located within the center of bottom
wo 93i a a o62 ~cri t~s~ a oo~~so
~~2J~3~
34
sheet 18, inwardly from both ends and from opposite sides, formed
of literally thousands of closely spaced, small diameter holes
or perforations 26 of near pin hole size. The perforations 26
are similar to those of U.S. Patent 4,528,704. Since the air
pallet 10 may be employed in a hospital environment, a nursing
home or resident home, it may be of a woven nylon fabric such as
a 70 x 100 denier 3.0 ounce square yard waterproof, vapor-
permeable nylon twill. One side may be coated with ZEPEZ
waterproof coating by DuPont and an appropriate anti-static
agent. The other side may be coated with approximately 1-1/4
ounce/square yard breathable tapable urethane and a suitable
bacteria stat agent. Of course, the nature of the thin flexible
sheet material making up the air pallet 10 as well as the other
embodiments of the invention herein may vary depending upon the
environment of use and the need for a special function or
characteristic property for a given sheet or sheets making up the
specific air pallet in question as well as the nature of forming
seal lines between sheets.
Line sealing between respective sheets 12 , 14 , 16 and 18 may
be effected by conventional thermal bonding techniques usinc3
linear heat application (under appropriate backing) on respective
sides of the multi-layer flexible sheet array. For the
embodiment of Figures 26-32, line sealing occurs along laterally
spaced longitudinal seal lines 28, longitudinally inwardly of
both air pallet ends 20, 22, between sheets 16 and 18 in
accordance with the pattern shown in Figure 29.
Next, a second, intermediate sheet 14 which is of shorter
width than that of sheets 16 or 18 is placed on sheet 16.
Further, linear thermal bond areas are effected to form seal
lines 30 as per Figures 27 and 31 at positions laterally offset
from the thermal bond seal lines 28 between sheets l6 and 18.
Two of the thermal bond seal lines are immediately adjacent to
the lateral edges 14a of thin flexible sheet 14. The last set
of longitudinally extending thermal bond seal lines 28 are
effected in accordance with the pattern shown in Figure 27
WO 93/ 11062 P(.'T/ fJS91 /08660
..
initiating from top sheet 12, evenly spaced laterally from each
other and including seal lines adjacent opposite lateral
edges 12a of that top sheet. Thermal bond longitudinal seal
lines 32 are formed by and between top sheet ,12., the .second
intermediate sheet 16 and bottom sheet 18 at lateral edges of the
air pallet 10. Inwardly of the edges, seal lines 32 are effected
at spaced lateral positions between sheets 12 and 14; laterally
offset from seal lines 30 between sheets 14, 16. Transverse
thermal bond seal lines 34 are required at both ends 20 and 22
of the air pallet 10 through all four sheets 12, 14, 16 and 18.
In some respects, the embodiment of the invention of Figures 26
through 32 inclusive relates to the air pallet of Figure 4 of
U.S. Patent 4,528,704. In that respect, the top sheet 12 is
provided with a air input or intake valve indicated generally
at 36, Figure 26, which may be a normally closed f lap type air
intake valve conventional to this art. Such valve is shown
schematically at 36 in Figure 26 and Figure 31. In order to
effect a constant pressure, compressed air pressurization of the
tubes, upper sect.on 40 of air pallet 10 defined by
sheets 12, 14, 16, in contrast to the lower section 42 formed by
the plenum chamber 68, sheets 16 and 18, the compressed air may
freely circulate to, between and through transverse channels at
the ends of seal lines 32 between sheets 12 and 14. Two rows of
holes 38 are pr~vided within the first intermediate sheet 14,
near respective opposite ends ~of the. sheet, spaced between
respective longitudinal seal lines 30 for sheets 14, 16 so that
air pressurization at constant pressure may be effected for the
chambers or tubes created 'by sheets 14 and 16 and the
longitudinal seal lines 30 therebetween. The effect of
particular longitudinal seal lines 30, 32 is to create-an upper
row of sealed chambers or tubes from left to right
at 44, 46, 48, 50, 52 and 54 , respectively, which are laterally
offset from integrated, second row chambers or
tubes 56, 58, 60, 62 and 64 defined by seal lines 30 sealing
sheets 14, 16.
WO 93/11062 PC1'/US91/08660
,,,
~~.~~~~~e~3~~ _
36
Upon air inf lation, as seen in Figure 32 , by the lateral
offsetting of the tubes of adjacent rows of tubes by the '
intermediate spacing of seal lanes 30 and 32 between respective
sheets 14 , 16 and 12 , 14 , a series of common walls rendered rigid
upon air pressurization of the chambers result~in the creation
of a semi-rigid backing member 66. For air pallet 10 formed by
the two rows of integrated tubes, the offsetting of the lower row
of tubes or chambers from that of the upper row and the use of
common walls formed by the same sheet for an upper row tube and
lower row tube constitutes both a means for reducing lateral
shrinkage of the plenum chamber portion bearing the perforations
26 creating the air bearing A and a means for rigidifying the air
pallet. It is the perforated area 24 defined by perforations 26
which creates the faotprint of the air bearing or film A, which
must be correlated to the footprint of the load formed by the
mass of patient P supported by the top thin flexible sheet 12.
Air under pressure, as from a source indicated schematically by
arrow 70, Figure 32 is applied to the air input or air.inlet
valve 72 in the same manner as that effected at 60, and via inlet
pipe 50 in U.S. Patent 4,528,704, Figure 2. Alternatively, a
f lap type inlet valve 72' to the opposite side, Figure 32, may
be employed for that purpose. Additionally, the air pallet 10
includes, at two longitudinally spaced positions on respective
sides 10a of the air pallet 10 and integrated to the stack of
sheets, U-shaped hand-holds 74 coupled thereto via a common base
strips 76. Base strips 76 may be thermal bonded or otherwise
sealed to the stack of sheets 12, 14, 16 and 18, and function as
supports for body straps 78, 80, one adjacent to each of the
hand-holds 74. Straps 78, 80 may include, respectively, VELCRO
cooperative mating hook and loop type fastener strips such as
those set forth in U.S. Patent 4,686,719, at 78 and 80.
It should be appreciated that for the air pallet of Figure 4
of U.S. Patent 4,528,704, the existence of the single array of
side-by-side coupled hollow tubes, the air pallet formed thereby
shrinks laterally to a significant degree during gas (air)
wo ~3m ~ obz Pcrius9' io~66o
P r~ ~ ~..
37
pressurization of the tubes. This results in a slackening of the
thin, flexible bottom sheet 18, and the possible rendering of the
air pallet inoperable, due to the tendency for the air pallet
partially formed thereby to balloon.. ,_~ , w
The air pallet 10 of the present invention i.s characterized
by means limiting lateral shrinkage of the portion of the plenum
chamber 68 beneath the footprint of the load, as defined by the
mass distribution of the patient P, particularly over the lateral
width of air bearing A. In the case of the embodiment of
Figures 26-32, and as shown particularly in Figure 32, the thin,
flexible sheet 18 as a result of the existence of longitudinal
seal lines 28 sealed to respective faces of sheets 16, 18
defining the bottom row of chambers 56, 58 and 62, 64, excess
slack is eliminated within the perforated area of the thin,
flexible bottom sheet 18. The footprint of the air film A then
matches or substantially matches the footprint of the load P, as
a result of the constant pressure maintained within
chambers 44-64, inclusive, of the dual rows of chambers.. The
full width of sheet 14 acts to form the common walls for all
tubes of the upper row and all tubes of the lower row, which
common walls are rendered taut and rigid under tension, due to
full pressurization of tubes 44-64.
In the embodiment of Figures 26-32, it is preferred that the
upper section 40 of the air pallet 10 include a pressure relief
valve as at 82 for limiting the air pressure in tubes 44
through 64. Under certain circumstances, the air pallet 10 may
include a further thin, flexible sheet 18°, as shown in dotted
line, Figure 32, sealed longitudinally along the sides thereof
at 84 to the outer edges of the top sheet 12, and linearly at 86
to certain of the chambers or tubes such as 46, S2. An air input
valve '72 similar to that for the lower section 42 permits the
compressed air pressurization of an upper plenum chamber 88.
Further, the fifth thin, flexible sheet 18' in the proposed
modification of Figure 32 includes a central perforated area 24'
which mirrors that at 24 of the bott~m sheet 18. An air
WO 93/11062 PC_'T/US91108t~0
~~24~~)
38
bearing A' may be created beneath patient P upon pressurization
of the upper plenum chamber 88 via compressed air from a source
indicated by arrow 89, either alternatively or simultaneously
with air bearing A from source 70. Such structure may be used
with a tent (not shown) to supply a medicament in vapor form
about the patient with said tent set over the air pallet 10.
The pressure relief valve 82 automatically maintains the
pressurization of the tubes or chambers within the upper
section 40 of the air pallet below 32 mm of mercury pressure to
prevent patient capillary closure. Under such conditions the
patient is in therapy, and the function of the pressure relief
valve~is to regulate the pressure independently of the weight of
the patient with the pressure relief valve preferably set to open
at 30 mm of mercury (preset far valve 82). This is particularly
desirable where the air pallet 10 functions as an operating roam
mattress pad. When patients are in the operating room in a
fixed, supine position, skin breakdown can develop within a very
short period of time. The air chambers become near rigid.under
an air pressure of 32 mm of mercury, and air pressurization at
that level tends to prevent spinal flexure.
The air pallet 10 forming a preferred embodiment of the
invention therefore constitutes an air chamber-type of flexible
air pallet for frictionless movement of a flexible load supported
thereon 6patient or inanimate object) relative to an underlying
generally planer f fixed support surf ace . Such air pallet includes
means forming a flexible generally glanar backing surface
underlying the load. A thin flexible sheet directly or
indirectly underlies the flexible backing surface and directly
overlies the planar support surface having that portion facing
the generally planar fixed support surface perforated, conforming
to the footprint of the load and defining with the flexible
backing surface at least one plenum chamber. The pin hole
perforations open unrestrictedly directly to the plenum chamber.
The means forming said backing surface comprises at least one
flexible backing chamber underlying the load. Air dispersion
WO 93/ 11062 PCT/US91 /08660
39
means are operatively associated with the at least one plenum
chamber to ensure air f low throughout said at least one plenum
chamber when the air pallet is under load. The air pallet
further comprises means for controlling pillowing, of the flexible
sheet portion of said at least one plerum chamber to j ack the
flexible backing surface and the load sufficiently to permit the
air pallet to accommodate surface irregularities for both the
load support surface and the flexible backing surface without
ballooning. The air pallet includes lateral anti-shrink means
for restricting the reduction in air pallet size that occurs in
a plane parallel to the air bearing during pressurization of said
at least one flexible backing chamber. Further, at least one
common member (sheet 14) is joined at spaced positions,
respectively,._to said at least one flexible backing chamber of
the upper row o~ chambers and said at least one flexible chamber
of the lower row of chambers. Air inlet means 72, 82 function
to pressurize said chambers to cause said at least one common
member to become rigid and to thereby render said flexible,
genera'.ly planar backing surface at least semi-rigid to at least
support said load and to produce an air bearing upon jacking of
the flexible backing surface and said load above said fixed
support surface by escape of compressed air from said plenum
chamber through said perforations. The sheet 14 which ~,as
portions common to the upper row of tubes and the lower row of
tubes form a series of such linked "common members" or common
walls.
By supplying compressed air to multiple stacked chambers
there is provided adequate separation between the f lexi_ble load,
tine flexible generally planar backing surface underlying said
load and the generally planar fixed support surface irrespective
of loss of pressurization in a given one of said stacked f lexible
chambers.
Figure 32a shows a modification of the air pallet 10, at 10'
which is of the flow through typE, using a single source of air
under pressure. Air pallet 10' t:~s like elements to that of air
WO 93/11062 PC1'/US9i/08b60
..::,,
pallet 10 bearing like numerical designations. Additionally
holes or ports 38a within sheets 14 and 16 permit flow of
compressed air from a single source 70 through a single inlet 72
to f low through the upper and lower rows of tubes' defining
multiple stacked backing chambers and thence~through plenum
chambers 68 via pin hole perforations 26 to form air bearing A.
Referring to Figures 33-38, inclusive, a further embodiment
of the present invention in the form of a f low through soft pad
or bladder type air pallet 10°' is shown. The air pallet 10 "
is formed similarly to that of the embodiment of Figures 26-32
and is created by sewing together, thermal bonding, or heat
sealing along narrow linear lines, a plurality of thin flexible
sheets, in this case four in number. In air pallet 10 " , like
elements to the embodiment 10 bear like numeral designations.
Further, the thin flexible sheet material may be identical. to
that employed in the first embodiment. However, in this
embodiment, the row of physically linked tubes are not under
constant air pressure, nor are the chambers completely sealed as
in the air pallet 10 of Figure 26. As a result, the sheet
material may be other than completely imperforate, and sewing may
be employed to connect the sheets together along seal lines
instead of thermal bonding, in which case slight air leakage may
occur at the stitching.
Referring to the drawings, the four sheets are a top sheet
indicated generally at 12, a first intermediate sheet indicated
generally at 14, a pair of opposite hand, second .intermediate
sheets 16, and a bottom sheet indicated generally at 18. Instead
of the sheets being of rectangular form and different sized, the
top sheet and bottom sheet 12, 18 are configured as a modified
octagon having a squared, extended section 13 at one, foot
end 20; the opposite head end 22 being devoid of such generally
rectangular extension. At extension 13 there is provided a pair
of air input or inlet valves 72 and 72' to the right and left,
respectively, at the lateral edges 12a of the top thin flexible
sheet 12.
WO 93/ 11062 P~:T/ LJS91 /086b0
~ ,.
~ .~ ~ ,~ w _
41
The air pallet 10'° has particular application as a patient
mover; however, it is not generally employed as an air mattress
which is a principal function of the embodiment of Figure 26.
The first intermediate sheet 14 is, for instance, ,approximately 6
feet in length, corresponding to the overall length of the air
pallet 10 " . It is of modified rectangular plan form, having
opposite side edges 14a tapered at 15 towards the foot end 20 of
the air pallet . The f first intermediate sheet 14 is provided with
four small diameter holes forming air flow ports 17 between the
upper row tubes partially defined by sheet 14 and the top
sheet 12 when sealed together in the manner of Figure 37 and
lower row tubes defined by sheets 14 and 16. The holes 17 appear
within the rectangular portion of the sheet 14 closer to the
end 22 of the air pallet than end 20.
Two second intermediate sheets 16 are employed in the air
pallet 10 " and are relatively narrow. They are of modified
rectangular plan configuration, including a rectangular
portion 19 which is proximate to head end 22 of the air
pallet 10 " and a laterally inward oblique portion 21 near the
opposite foot end 20 of the air pallet 10' ' . They are each of
generally the same length as the air pallet 10 " and the balance
of the thin flexible sheets making up that assembly. The
angulation of portion 21 conforms to the tapering of the top and
bottom sheets 12, 18 of the lateral sides of those two members
at foot end 20. Each of the second intermediate sheets 16
employed in the structure includes two longitudinally aligned
holes or air f low ports 23 within the rectangular section 19 of
the thin flexible sheet 16.
The thin flexible bottom sheet 18, although configured to
that of the top thin flexible sheet 12, includes a modified
perforated area 24 bearing thousands of closely spaced pin hole
type perforations 26 in the manner of the embodiment of Figure 10
as shown in Figure 30, within the center of sheet 18. The
lateral and longitudinal dimensions of the thin flexible sheets
for the air pallets 10 and 10' may be generally identical, as
WO 93/11062 P(:T/US91108b60
2~w~~~~~
42
well as the perforated area 24 of each bottom sheet I8 for the
respective embodiments. The sire of the perforated area 24 is
determined by the mass of the patient or other load transported
by the air pallet and the mass distribution of ,that load. The
mass of a human body lies principally in the gunk, and this is
the area of perforation disposition such that the footprint of
the load conforms to the perforated area 24 of sheet 18, and thus
the footprint of the air bearing A created beneath the bottom
thin flexible sheet 18.
These general relationships exist for all of the embodiments
of the invention described herein, and as shown in the drawings
accompanying this description including embodiments 10, 10'
and 10 ". The stacked sheets for air pallet 10 " at 12, 14, 16
and 18 are illustrated schematically in Figure 37 vertically
separated so that the generation of the tube array may be
appreciated in the completion of the air pallet structure by seam
sewing, thermal bonding, or the like, at predetermined positions,
and along lines extending over given lengths of the stacked
layers of sheets. By reference to the various Figures 33-37,
inclusive, with the thin flexible bottom sheet in place, a pair
of opposite hand, second intermediate sheets 16 are positioned
on sheet 18 and are bonded thereto along opposite lateral side
edges via seal lines 28 over the full length of the air pallet,
as evidenced in Figure 35. Next, a first intermediate thin
flexible sheet 14 is positioned so that its opposite lateral
edges 14a overlap portions of the opposite hand sheets 16, and
with sheet 14 centered laterally of the assembly of
sheets 14, 16, 18. As may be appreciated, as per Figure 34,
w laterally spaced, longitudinal seal lines are effected between
sheet 14 and respective opposite hand sheets 16 as at 30 adjacent
the lateral sides 14a the first intermediate thin flexible
sheet 14. Those seal lines may be effected simultaneous with
seal lines bonding the thin flexible sheet Z4 to the top thin
flexible sheet 12. zn order to effect that action, it is
preferable to insert a backing anvil positioned beneath the thin
WO 93/ 11062 PC'I'f U~91 /086b0
- ~. ~ .~ ~~
-~~ -
43
flexible opposite hand sheets 16 at the location of the two
longitudinally extending parallel seal lines 30. If stitching
is to be employed in the creation of the seal lines demarcating
the various tubes or chambers, such anvil or b~cking,member is
not necessary. Lastly, the thin flexible top sheet 12 is placed
on top of thin flexible sheet 14 completing the array. All four
sheets 12, 14, 16 and 18 are sewn or thermo bonded together along
top and bottom edges thereof. In this embodiment, five laterally
spaced, longitudinally extending seal lines 32 are required to
complete the assembly, including a seal line 32 at the lateral
center, Figure 33, to each side thereof and aligned with or
supplementing seal lines.30-.-. extending through the first
intermediate sheet 14 and the opposite hand sheets 16, as per
Figure 37. Outer edge seal lines 32 are effected solely between
the top thin flexible sheet 12 and bottom sheet 18 along the
lateral edges of sheets l2 and 18. Since this is a compressed
air flow through type "soft pad" air pallet, the seal lines do
not have to completely seal off the various tubes formed thereby.
Air flow which is initiated from inlet valve 72 or 72', via
source 70 at end 20 of the air pallet 10 " passes through four
upper tubes or chambers 45, 47, 49 and 51, Figure 37, and then
via the small diameter ports 17 into central tube or chamber 55
of the lower row of tubes, and simultaneously by holes or
ports 23 within the opposite hand intermediate thin flexible
sheets 16 into the chambers or tubes 53 and 57 of the lower row
of tubes. For flow to occur and for air pressurization of the
chambers to occur simultaneously, smoothly in longitudinal
progression and at equal pressure, the laterally central seal
line 32 initiates at some distance from end 20 of the air
p211et 10 " and extends completely to the opposite end 22 of the
air pallet. Seal lines 32 to opposite sides of the center seal
line are initiated closer to end 20 and terminate short of end 22
by a distance of approximately 2 inches in this embodiment 10 "
which is approximately 6 feet in length. As a result, there is
no jolt to the patient lying thereon, or a series of jolts by
WO 93/11062 P(_'T/US91~/08660
4
44
unequal air pressurization through parallel tubes with head jolt
upon lift during jacking of the patient due to air f low through
the row of tubes forming flexible backing chambers defined by
three of the four sheets 12, 14, 16 upon air pressurization. In
Figure 34 the sewn seal line 32, common with the top sheet 12 is
indicated on the first intermediate sheet 14. Additionally, seal
lines 30 extend from a point near the pallet air inlet foot
end 20, but not at that end, and continue towards the opposite
end 22, but terminate short of that end by approximately three
inches in the illustrated embodiment. This permits air
equalization within at least all upper tubes forming flexible
backing chambers 45, 47, 49 and 51 and eliminates patient trauma
induced jolts. From Figure 35 it may be seen that the laterally
spaced seal lines 28, sealing lateral edges of the opposite hand
sheets 16 to the bottom sheet 18 extend over the full length of
the air pallet 10' from foot the air inlet foot end 20 to the
opposite head end 22. As shown in Figure 35, the seal lines 30
sealing a lateral edge of intermediate sheet 14 to the near
lateral center of the opposite hand intermediate sheets 16 are
initiated at some distance from the air inlet, foot end 20, and
terminate short of the opposite head end 22.
Air pressurization is achieved through an inlet valve ?2,
schematically illustrated as a relatively small diameter tube in
Figures 37 and 38, with the compressed air emanating from a
supply or source indicated schematically by arrow 70. Air
pressurization of the upper row of flexible backing
chambers 45, 47, 49 and 51 is higher than that of the lower row
of laterally offset, integrated tubes forming multiple plenum
chambers 53, 55 and 57 defining air bearing A since the air
enters the lower tubes from the upper row tubes through the
multiple small diameter holes or air f low ports 23, 17.
Preferably there are two or more longitudinally spaced holes
feeding air from a respective upper row tube to a lower row tube.
WU 93/ 11062 ~'~'3f'/ iJS91 /~866m
~'~ .r "a
C' ~i,i~:Y.~P.av
Unlike the embodiment of Figure 26, the patient mover type
air pallet 10 " of Figures 33-38 has no means for providing
rigidity due to the nature of the construction and configuration
of the upper tubes defined by sheets 12, 14. , The ,air inlet
valves 72, 72' may take appropriate form, such~as that shown in
U.S. Patents 4,272,856 and 4,528,704. These valves automatically
self seal when not in use so that the valves 72, 72' may be
alternarively employed. In patient mover use, the end 20 becomes
the foot end of the patient mover air pallet 10' and the opposite
end 22 the head end. Air pressurization causes the collapsed
thin f lexible sheet formed soft pad air pallet la " to initially
fill the upper row flexible backing chamber tubes 45, 47, 49
and 51 and then the lower row plenum chamber tubes 53, 55 and 57
in sequence prior to the creation of the air bearing A by escape
of the air flow through the perforations 26. In this case,.the
feet of the patient P are initially jacked prior to jacking of
the patient's head. Trauma ~.s not produced since the gas
pressurization is uniform in development, and equal for
respective tubes of the upper row tube arxay, and with the air
pressure within the tubes of the lower row or array being
slightly less due to the pressure drop caused by the air passage
holes 17, 23. Figure 38 shows the severe actions of hot d~gging
of air pallet 10 " upon air pressurization, principally due to
the size and lack of anti-shrink prevention means within central
plenum chamber 55.
The air pallet 10 " , with the exception of spacing the head
end longitudinal seal lines 32, 30 from the transverse seal
line 34 at the edge of the air pallet 10 (commonly sealing off
all sheets 12, 14, 16, 18 along narrower linear surface areas)
is considered to be prior art to the subject matter of this
invention. Further, certain of the means for controlling
performance of air pallet 10 " have basis in U.S.
PateritS 3,94$,$44 and 4,417,639.
The shrink prevention means for patient mover 10 and lacking
in patient mover 10 " or like air pallets may take various forms
WO 93/ 11062 PCT/US91 /08660
~1~~~
46
and the geometry for creating structure providing that function
may consist solely in thin flexible film material or the '
incorporation of semi-rigid or generally rigid elements of solid
or hollow frame construction. , .
Figure 39 is a vertical sectional transverse sectional view
of a further patient mover type air pallet 10 " ' as a
modification of the air pallet 10, Figure 26-32, which, and in
all other respects, includes the content of the drawing figures
of that embodiment with like elements using like numerical
designations. Air pallet 10 " ' utilizes the same four thin
flexible sheets, a top sheet 12, a bottom sheet 18, two
intermediate sheets 14, 16 to make up the thin flexible film
formed structure for supporting a patient such as at P. Air
pallet 10 " ' incorporates an additional intermediate thin
flexible sheet 25 positioned between sheets 16 and 18 and edge
sealed thereabouts on three sides, thus forming a backing member
cavity 27 therebetween. A generally rigid board or sheet such
as sheet 29, is provided within cavity 27 constituting additional
lateral anti-shrink means for segmented plenum chamber 31.
Additionally, in Figure 40, this embodiment has the first
intermediate sheet 14 imperforate, and accordion pleated with the
edges of the pleats as at 33, thermal bonded or otherwise sealed
longitudinally, alternatively to respective opposing surfaces of
the top sheet 12 and the second intermediate sheet 16 to form
closed sealed flexible backing chambers or tubes similar to that
of Figure 24. These consist of an upper row of chambers or
sealed hollow tubes 35 and a lower row of such tubes 37 with
common walls 41 subjected to pressurization on opposite sides by
a chamber 35 and 37, respectively. Since the corrugated walls
are common to two tubes, one on each side of an oblique wall,
such common walls are rendered taut or rigid acting as I beams
and this structure resists the tendency for the air pallet to hot
dog, i.e., the opposite lateral edges to curl in response to gas
pressurization of these chambers. Sheet 29 may be dispensed with
since the flexible backing chambers render the air pallet
WO 93/11062 PC"I'/US9i/08660
47
generally rigid upon air pressurization. Additionally, the
bottom thin flexible sheet 18 over the extent of the lateral
perforated area bearing perforations 26, forms a series of
adj acent plenum chambers or chamber sections 31 with the sheet 18
bonded to the bottom of the thin flexible sheet 25 at laterally
spaced seal lines 39 which extend longitudinally and which
additionally assist in maintaining the air bearing at A. Air
under pressure is supplied through air inlet valve 72' to the
left, and via a common transverse manifold (not shown) open to
the balance of the segmental plenum chamber 31.
Alternatively, a rigid rectangular open frame 41, Figure 40,
may be inserted within backing member cavity 27, Figure 39, whose
longitudinally extending, laterally spaced beams 41a prevent
lateral shrinking of the plenum chamber 31 such that the
footprint of the air bearing A remains adequately sized for. the
footprint of the mass distribution of the load (patient P)
positioned on the upper surface of the top thin flexible
sheet 12. In a variation, the patient mover air pallet_10 " '
could be positioned within the frame 41 opening and strung on the
frame by tensioned cords with the f came providing an exterior
anti-shrink function.
Turning next to Figure 41, a further embodiment of the
patient mover type air pallet 10 " " is illustrated, again being
a vertical sectional view corresponding to the air pallet 10
embodiment shown in Figure 32 with modifications as shown in the
drawings. Otherwise the air pallet 10 " " corresponds to air
pallet 10, as described and shown in detail. One respect in
which the structure 10' ' ' ' is modified resides in the utilization
of vertical and oblique ties 43 formed of perforated flexible
sheet material, being thermal bonded, sewn, heat sealed or the
like at opposite ends to the thin flexible perforated bottom
sheet 18 and to the second intermediate sheet 16 respectively.
These ties 43 act, when taut, as additional physical restraints
to prevent the structure from hot dogging, in response to air
pressurization of the upper and lower rows of tubes 44 through
wo 93m ao~z Pcrius9mos~o
,.
~Jl~~zarc
43
64, inclusive and the plenum chamber. While the dual tube array
in Figure 41 corresponding to Figure 32, by having common walls
of side by side laterally offset upper and lower row flexible
backing chamber tubes, equally pressurized, normally adequately
prevents excessive shrinkage of the portion' of the plenum
chamber 68 forming the air bearing A such that the footprint of
the air bearing A between the air pallet 10' ' ' ' and the rigid
planar support surface 11 beyond that capable of supporting the
load P over its footprint, the ties 43 further assist in that
purpose. Such ties may in themselves solely provide that
function in a soft pad or hard pad air pallet. With the
tubes 44-~64 under constant pressure by application of compressed
air to the tubes as per arrow 89 similar to the embodiment of
Figure 26, the application of a low cfm flow of air from a source
indicated as arrow 70 through the air inlet valve 72 to plenum
chamber 68 creates the air bearing A over a perforated area whose
footprint may be readily maintained between 75~ and 100 of the
footprint cross sectional area of the load provided by the
patient P supported by the pallet 10 " " .
While the invention has been particularly shown and
described with reference to preferred embodiments 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.
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