U.S. patent number RE35,299 [Application Number 08/157,890] was granted by the patent office on 1996-07-23 for air chamber type patient mover air pallet with multiple control features.
This patent grant is currently assigned to Robert E. Weedling. Invention is credited to David T. Davis, Raynor Johnson, William R. Swallen, Robert E. Weedling, Jack Wegener.
United States Patent |
RE35,299 |
Weedling , et al. |
July 23, 1996 |
Air chamber type patient mover air pallet with multiple control
features
Abstract
Air chamber-type air pallets incorporate side-to-side linked air
pressurized tubes or chambers in two integrated rows, having common
members for adjacent chambers under air pressurization rendered
rigid over a certain extent to rigidify the air chambers thereof
which form load backing chambers in place of rigid backing members
conventionally employed in air pallets maintaining the load
footprint borne by the air pressurized backing chambers matched by
that of the developed air bearing or air film by passage of
compressed air through the pattern of perforations. Preferably,
linked tubes of one row are laterally offset but integrated
physically to those of a second row to both limit lateral shrinkage
of linked tubes extending completely across the pin hole
perforations within the thin, flexible bottom sheet partially
forming such air pallets. The use of upper and lower rows of tubes
subject to air pressurization provides adequate separation between
the load and the fixed support surface to prevent contact of the
load and the fixed support surface irrespective of loss of
pressurization of a given one of the tubes of either row. The air
pallets are formed totally of thin, flexible sheet material,
permitting deflation and transfer from one locale to another. The
air pallets function as stable supports for the patient during
transport over the developed air film between the patient mover and
an underlying fixed support surface. A single row of linked tubes
formed of two thin, flexible sheets, acting as plenum chambers and
having perforations within the thin, flexible bottom sheet
functions adequately to support the patient directly on the top
thin, flexible sheet with the bottom tangential surfaces of the
individual tubes flattening. Preferably the area of perforations
for each tube is limited transversely to the flattened portions of
those tubes facing the underlying fixed support surface, with the
developed air film having a surface area matching that of the
patient.
Inventors: |
Weedling; Robert E.
(Stockertown, PA), Swallen; William R. (Stockertown, PA),
Johnson; Raynor (Newark, DE), Wegener; Jack (Preston,
MD), Davis; David T. (Easton, PA) |
Assignee: |
Weedling; Robert E. (Allentown,
PA)
|
Family
ID: |
24019011 |
Appl.
No.: |
08/157,890 |
Filed: |
November 24, 1993 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
507534 |
Apr 11, 1990 |
05067189 |
Nov 26, 1991 |
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Current U.S.
Class: |
5/81.1T; 180/125;
414/676; 5/713 |
Current CPC
Class: |
A61G
7/1028 (20130101); A61G 7/103 (20130101); B60V
3/025 (20130101); A61G 7/1021 (20130101); A61G
2200/32 (20130101) |
Current International
Class: |
A61G
7/10 (20060101); B60V 3/02 (20060101); B60V
3/00 (20060101); B65G 007/06 (); A61G 007/14 () |
Field of
Search: |
;5/81.1,453,455,423,469
;180/125,124,116 ;414/676 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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177370 |
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Mar 1922 |
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GB |
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1096120 |
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Dec 1967 |
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GB |
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Primary Examiner: Grosz; Alexander
Attorney, Agent or Firm: Piltch; Sanford J.
Claims
What is claimed is:
1. A patient mover air pallet for frictionless movement of a
patient over an underlying, relatively fixed support surface, said
patient mover air pallet comprising:
top, intermediate and bottom thin flexible sheets,
means for sealing given sheets together linearly to define a plenum
chamber between said intermediate and bottom sheets,
.[.at least one backing member cavity between said top sheet and
said intermediate sheet,.]. said bottom thin flexible sheet
including a portion defined by the footprint of the load having a
plurality of closely spaced small diameter pin hole type
perforations opening directly into the plenum chamber and directly
onto said support surface,
air inlet means communicating with the plenum chamber at one end
thereof for permitting low pressure air flow pressurization of the
plenum chamber for initially jacking the load and for subsequent
discharge through the perforations to create a thin air film
between the bottom thin flexible sheet and the support surface,
means including said top thin flexible sheet defining a semi-rigid
backing member so as to define with the plenum chamber air
dispersion means for insuring air flow throughout the plenum
chamber when the air pallet is under load at the time of air
pressurization of the plenum chamber.Iadd., .Iaddend.and
constituting with said bottom thin flexible sheet.[.,.]. means for
controlling pillowing of the thin flexible sheet material to permit
jacking of the semi-rigid backing member and the load while
preventing ballooning of the thin flexible sheet material,
wherein said semi-rigid backing member permits deflection of the
patient mover somewhat to conform the patient mover to depressions
within the support surface to permit transport of the patient via
the patient mover air pallet over said support
surface.Iadd.,.Iaddend.
wherein said top thin flexible sheet is sealed to said intermediate
thin flexible sheet along longitudinal parallel lines at laterally
spaced positions across the surface of the intermediate thin
flexible sheet and at both ends thereof to form a series of
longitudinally extending tubes, and
wherein means are provided for supplying air under pressure to the
individual tubes formed thereby in addition to air pressurization
of the plenum chamber such that the tubes cradle the patient while
facilitating transport of the patient over the support surface on
the frictionless air film,
the improvement comprising means for substantially restricting
lateral shrinkage of the portion of the plenum chamber in the area
of said perforations parallel to the plane of the developed air
film for maintaining the footprint of the air film generally equal
to that of the footprint of the load to insure stable support of
the patient on the patient mover air pallet, and for preventing
loss of said air film and grounding of the air pallet to the
underlying support surface.
2. The patient mover air pallet as claimed in claim 1.Iadd.,
.Iaddend.wherein said means for substantially restricting lateral
shrinkage of said plenum chamber over the width of said perforated
portion of said thin flexible bottom sheet comprises two integral,
linked vertical rows of said tubes extending transversely with the
tubes of one row being laterally offset with respect to the other
over the full lateral width of the perforated portion of the thin
flexible bottom sheet such that the centers of tubes in one row are
aligned with abutting peripheries of tubes of the adjacent row and
adjacent tubes of said two rows have a common wall under
pressurization to opposite sides rendered thereby .[.taunt.].
.Iadd.taut .Iaddend.and rigid, and wherein said taut common walls
render said two rows of tubes rigid under said load to stably
support said load thereon.
3. The patient mover air pallet as claimed in claim 2.Iadd.,
.Iaddend.wherein said linked rows of tubes are sealed from said
plenum chamber, and means are provided for separately supplying
compressed air to said linked rows of tubes from that supplied to
said at least one plenum chamber.
4. The patient mover air pallet as claimed in claim 3, further
comprising a pressure relief valve operatively coupled to said
linked rows of tubes and set to prevent the pressure therein from
reaching a level inducing capillary closure of the patient
supported by said patient mover air pallet.
5. The patient mover air pallet as claimed in claim 4, wherein said
pressure relief valve is a variably adjustable valve such that said
linked rows of tubes can be lightly air pressurized to form a
highly supple comfortable air mattress for supporting a patient
thereon over long periods of time without trauma, while providing
therapy to said patient.
6. The patient mover air pallet as claimed in claim 2, wherein at
least one of said tubes constituting said semi-rigid backing member
carries said air inlet means at one end thereof opening directly
thereto, and wherein at an opposite end thereof, an air flow port
opens to an integral linked tube of another row of tubes to permit
flow of low pressure air flow from one tube of one of said rows to
said tube of another row via said air flow port and wherein the
cross-sectional area of said air flow port is substantially less
than the cross-sectional area of said air inlet means such that
said one tube of said one linked row is at a higher pressure than
said other tube of said another linked row of tubes.
7. The patient mover air pallet as claimed in claim 2, wherein
openings are provided within said tubes of one row which open
directly into tubes of the adjacent row, and wherein said tubes of
said one or said adjacent row have further openings which open
directly into the plenum chamber, and wherein at least one of said
tubes of one of said rows carries air inlet means at one end
thereof opening directly thereto, such that said patient mover air
pallet constitutes a flow through soft pad with said flow of air
being through said tubes of integral linked rows, and through said
plenum chamber to effect said means for substantially restricting
lateral shrinkage of the plenum chamber, while providing
simultaneously said air film.
8. The patient mover air pallet as claimed in claim 2, wherein
.Iadd.said .Iaddend.air pallet includes a second.[.,.].
intermediate thin flexible sheet, said second intermediate.[.,.].
thin flexible sheet is interposed between said first intermediate
thin flexible sheet and said top sheet, and wherein said means for
sealing given sheets together linearly comprise seal lines
extending longitudinally over a given length of said thin flexible
sheets at laterally spaced positions, such that said integral
linked rows of .[.end-to-end.]. tubes are formed solely by said top
and bottom thin flexible sheets and said first and second
intermediate thin flexible sheets, and seal lines extending at
least between two immediately adjacent flexible sheets.
9. The patient mover air pallet as claimed in claim 8, wherein said
intermediate thin flexible sheets include holes therein forming air
flow ports between respective tubes defined by said at least two
immediately adjacent sheets and between laterally spaced seal lines
for permitting air pressurization of a plurality of tubes formed
thereby from a common source of air under pressure.
10. The patient mover air pallet as claimed in claim 8, wherein
said bottom thin flexible sheet bearing said perforations includes
means for coupling said bottom thin flexible sheet to said
immediately adjacent intermediate thin flexible sheet at laterally
spaced positions substantially across the extent of said area of
perforations, so as to provide individual segments to said plenum
chamber to prevent excessive slack in said bottom thin flexible
sheet and bottoming out of the patient on the underlying relatively
fixed support surface during air pallet operation and hot dogging
of said air pallet.
11. The .[.patent.]. .Iadd.patient .Iaddend.mover air pallet as
claimed in claim 8, further comprising a third.[.,.]. intermediate
thin flexible sheet edge sealed to intermediate thin flexible
sheets to opposite sides thereof, and defining a backing member
cavity, and
wherein a generally rigid backing member is carried within said
cavity and comprises part of said means for substantially
restricting lateral shrinkage of said plenum chamber over at least
the width of said perforated portion of said bottom thin flexible
sheet.
12. The patient mover air pallet as claimed in claim 8, wherein
said means for substantially restricting lateral shrinking of said
plenum chamber over at least the width of said perforated portion
of said thin flexible bottom sheet comprises ties within said
plenum chamber, having opposite ends fixed respectively to said
bottom thin flexible sheet and said intermediate thin flexible
sheet proximate thereto forming said integral linked rows of tubes
extending transversely across the width of said air pallet.
13. The patient mover air pallet as claimed in claim 12, wherein
said ties extend perpendicularly through said plenum chamber at
right angles to the plane of said air film and that of the patient
supported thereby.
14. The patient mover air pallet as claimed in claim 12, wherein
said ties extend obliquely from said bottom thin flexible sheet
inwardly towards the center of said plenum chamber to engage said
integral linked rows of tubes to restrict movement of said bottom
thin flexible sheet away from the integral linked rows of tubes and
towards the respective lateral sides of said patient mover air
pallet.
15. A flexible air pallet for frictionless movement of a flexible
load supported thereon relative to an underlying generally planar
fixed support surface, said air pallet including:
a first thin flexible sheet forming a flexible, generally planar
backing surface underlying the load,
a second thin, flexible sheet underlying the flexible backing
surface and directly overlying the planar support surface,
said second thin, flexible sheet having a portion facing the
generally planar fixed support surface perforated over a surface
area generally conforming to the footprint of the load and defining
with the flexible backing surface, at least one plenum chamber,
said perforations opening unrestrictedly directly to the plenum
chamber,
air dispersion means operatively associated with said at least one
plenum chamber to insure air flow throughout said at least one
plenum chamber when the air pallet is under load,
means for controlling pillowing of the thin, flexible sheet portion
of said at least one plenum chamber to jack 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,
and
air inlet means for supplying compressed air to said at least one
plenum chamber,
the improvements wherein said air pallet includes within said at
least one plenum chamber, at least one flexible common member
joined at spaced positions respectively to said first and second
flexible sheets within the perforaed area underlying the footprint
of the load and being of limited length, whereby said air inlet
means in supplying air under pressure to said at least one plenum
chamber causes said at least one common member to become taut and
rigid and to thereby render said flexible, generally planar backing
surface at least semi rigid to at least support said load and to
produce an air film upon jacking of the flexible backing surface
and the load above said fixed support surface by escape of
compressed air from said at least one plenum chamber through said
perforations, and said at least one flexible common member defining
lateral anti-shrink means for restricting the reduction in air
pallet size in a plane parallel to the air film during air
pressurization of said at least one plenum chamber.
16. The air pallet as claimed in claim 15, wherein said at least
one flexible member is a third thin, flexible sheet joined at
lateral spaced positions alternatively to said first and second
thin flexible sheets.
17. The air pallet as claimed in claim 16, wherein
said third thin flexible sheet comprises a series of unitary
portions common to an upper row of tubes and a lower row of tubes,
said upper row of tubes defining plural flexible backing chambers,
and
said lower row of tubes defining a plurality of linked plenum
chambers, and wherein,
said upper and lower rows of tubes extend completely across the
area of said perforations and provide adequate separation between
the flexible load, the flexible generally planar backing surface
underlying the load and the generally planar fixed support surface,
irrespective of loss of pressurization in a given one of said tubes
of either of said rows of tubes.
18. A flexible air chamber-type air pallet for frictionless
movement of a load .[.support.]. .Iadd.supported .Iaddend.thereon
relative to an underlying generally planar fixed support surface,
said air pallet being formed of thin, flexible sheet material
consisting of a first thin, flexible sheet at least partially
defining a flexible, generally planar backing surface for
supporting said load thereon, and
a second thin, flexible sheet directly underlying and sealed to
said backing surface and directly overlying said fixed load support
surface and being sealed thereto along longitudinal lines at
laterally spaced positions to form a series of laterally connected
plenum chambers, said second thin, flexible sheet having a
plurality of perforations therein facing said fixed support surface
within said linked plenum chambers, said perforations opening
directly into and out of said plenum chambers,
air dispersion means for said plenum chambers to insure air flow
through said chambers when said air pallet is under load,
air inlet means to said chambers for directing compressed air into
said plenum chambers for jacking said load and for discharge of
said air from the plenum chambers through said perforations to
create an air film between said thin, flexible bottom sheet and
said fixed support surface,
pillowing means to cause, upon air pressurization of said
chambers.Iadd., .Iaddend.said thin, flexible sheet portions of said
chambers to jack the backing surface and said load sufficiently to
permit the pallet to accommodate surface irregularities and to move
said load on said air film,
means for rendering said plenum chambers sufficiently rigid under
said load to support said load when said chambers are pressurized,
and
means for limiting the amount of lateral shrink across the air
pallet upon air pressurization of said plenum chambers so that said
air pallet plenum chambers can lift said load.
19. The flexible air chamber-type air pallet as claimed in claim
18, further comprising:
means for rendering said plenum chambers in the area of said
perforations sufficiently rigid to prevent load instability and to
prevent hot dogging of said linked plenum chambers underlying said
load.
20. The air pallet as claimed in claim 18, wherein said first thin,
flexible sheet is joined to said second thin, flexible bottom sheet
by longitudinally extending parallel seal lines to form a
side-to-side array of parallel tubes, with the lateral width
between the seal lines for one of said thin, flexible sheets being
significantly different from that of the other thin, flexible
sheet, thereby providing inherently the tendency to arch the thin,
flexible sheet whose lateral width between adjacent parallel seal
lines is narrower than that of the other thin, flexible sheet, upon
air pressurization of the linked plenum chambers.
21. Said flexible air chamber-type air pallet as claimed in claim
20, wherein said air pallet comprises hollow tubes extending
generally at right angles to said side-to-side array of tubes
defined by said first and second thin, flexible sheets at both
sides thereof and constituting said means for rendering said air
pallet plenum chambers generally rigid to prevent load instability
and for preventing grounding and insuring that the load is jacked
sufficiently from the underlying fixed support surface to permit
the pallet to accommodate surface irregularities and to move said
load on said air film.
22. The flexible air chamber-type air pallet as claimed in claim
18, wherein said thin, flexible bottom sheet tends to flatten in
the vicinity of the underlying relatively fixed support surface
under load, when said chambers are air pressurized, and
wherein the perforations within said plenum chambers exist solely
within the flattened area of said thin, flexible bottom sheet for
each of said plenum chambers, thereby maintaining the footprint of
the developed air film sized to that of said load.
23. A flexible film air chamber-type air pallet for frictionless
movement of a load supported thereon relative to an underlying
generally planar fixed support surface, said air pallet
comprising:
a flexible, generally planar backing surface for supporting said
load thereon,
a thin, flexible sheet directly underlying said flexible backing
surface and directly overlying said load support surface,
a portion of said thin, flexible sheet facing said general planar
fixed support surface being perforated and being sealed to and
defining with said backing surface at least one plenum chamber,
said perforations extending over an area generally corresponding to
the footprint of the load with said perforations opening directly
into said at least one plenum chamber,
air dispersion means for said plenum chamber to insure air flow
through said chamber when said chamber is under load and being
pressurized,
air inlet means opening to said at least one plenum chamber for
permitting air under pressure to enter into the plenum chamber for
jacking said load, for discharge of the air from said plenum
chamber through said perforations to create an air film between the
flexible, thin sheet and said fixed support surface over the area
of the perforations,
pillowing means for jacking the backing surface and said load
sufficiently to permit the pallet to accommodate surface
irregularities and move said load on a film of air without said
thin, flexible bottom sheet ballooning,
means for preventing said at least one plenum chamber from .[.hot
dogging.]. .Iadd.hotdogging, .Iaddend.for preventing load
instability.Iadd., .Iaddend.and for maintaining said at least one
plenum chamber planar in a direction parallel to the developed air
film for retention of the load on said backing surface during
movement of said load via said air pallet on said developed air
film, and
means for limiting shrink of the air pallet laterally parallel to
the plane of the developed air film over the surface area of the
perforations to insure that the footprint of the air film generally
matches that of the load.
24. The flexible air chamber-type air pallet as claimed in claim
23, further comprising means for rendering said flexible generally
planar backing surface rigid under said load to support said load
upon jacking when said at least one plenum chamber is air
pressurized.
25. In a flexible air chamber-type air pallet for frictionless
movement of a load supported thereon relative to an underlying
generally planar fixed support surface, said air pallet being
formed of thin, flexible sheet material comprising a first thin,
flexible sheet at least partially defining a flexible, generally
planar backing surface for supporting said lead thereon, and
a second thin, flexible sheet underlying said backing surface and
directly overlying said fixed load support surface and being
connected thereto along longitudinal lines at laterally spaced
positions to form a series of laterally connected, linked plenum
chambers, said second thin, flexible sheet having a plurality of
perforations therein facing said fixed support surface within said
linked plenum chambers, said perforations opening directly into and
out of said plenum chambers,
air dispersion means for said plenum chambers to insure air flow
through said chambers when said air pallet is under load,
air inlet means to said chambers for directing compressed air into
said plenum chambers for jacking said load and for discharge of
said air from the plenum chambers through said perforations to
create an air film between said thin, flexible bottom sheet and
said fixed support surface,
pillowing means to cause, upon air pressurization of said chambers
said thin, flexible sheet portions of said chambers to jack the
backing surface and said load sufficiently to permit the pallet to
accommodate surface irregularities and to move said load on said
air film, the improvement comprising:
means for controlling the amount of lateral shrink across the
pallet upon air pressurization of said plenum chambers so that said
air pallet plenum chambers can lift said load, and
means for rendering said first thin flexible sheet over the area of
said perforations sufficiently rigid to support said load when the
chambers are pressurized and means to prevent load instability and
.[.hot dogging.]. .Iadd.hotdogging .Iaddend.of said air pallet
under load.
26. A flexible film air chamber-type air pallet for frictionless
movement of a load supported thereon relative to an underlying
generally planar fixed support surface, said air pallet
comprising:
a flexible, generally planar backing surface for supporting said
load thereon,
a thin, flexible sheet underlying said flexible backing surface and
directly overlying said load support surface,
a portion of said thin, flexible sheet facing said generally planar
fixed support surface being perforated and being sealed to and
defining with said backing surface at least one plenum chamber,
said perforations extending over a surface area of said thin,
flexible sheet corresponding generally to the footprint of the load
with said perforations opening directly into said at least one
plenum chambers,
air dispersion means for said plenum chamber to insure air flow
through said chamber when said chamber is under load and being
pressurized,
air inlet means opening to said at least one plenum chamber for
permitting air under pressure to enter the at least one plenum
chamber for jacking said load, and for discharge of the air from
said plenum chamber through said perforations to create an air film
between the flexible, thin sheet and said fixed support surface
over the area of the perforations,
pillowing means for jacking the backing surface and said load
sufficiently to permit the pallet to accommodate surface
irregularities and move said load on a film of air without said
thin, flexible bottom sheet ballooning, and
means for preventing said at least one plenum chamber from .[.hot
dogging.]. .Iadd.hotdogging.Iaddend., for preventing load
instability, for maintatining said flexible backing surface planar
in a direction generally parallel to the developed air film for
retention of the load on said backing surface during movement of
said load via said air pallet on said developed air film and for
limiting shrink of the air pallet laterally, generally parallel to
the plane of the developed air film to insure that the footprint of
the air film generally matches that of the load, and means for
rendering said flexible generally planar backing surface
sufficiently rigid under said load to support said load upon
jacking when said at least one plenum chamber is air pressurized.
.Iadd.
27. The patient mover air pallet as claimed in claim 8, wherein
said integral linked rows of tubes are sealed from said plenum
chamber, and means are provided for separately supplying compressed
air to said linked rows of tubes from that supplied to said at
least one plenum chamber. .Iaddend..Iadd.28. The patient mover air
pallet as claimed in claim 27, further comprising a pressure relief
valve operatively coupled to said linked rows of tubes and set to
prevent the pressure therein from reaching a level inducing
capillary closure of the patient supported by said patient mover
air pallet. .Iaddend..Iadd.29. The patient mover air pallet as
claimed in claim 28, wherein said pressure relief valve is a
variably adjustable valve such that said integral linked rows of
tubes can be lightly air pressurized to form a highly supple
comfortable air mattress for supporting a patient thereon over long
periods of time without trauma, while providing therapy to said
patient. .Iaddend..Iadd.30. The patient mover air pallet as claimed
in claim 12, wherein said ties extend perpendicularly through said
plenum chamber at right angles to the plane of said air film and
that of the patient supported thereby and obliquely from said
bottom thin flexible sheet inwardly towards the center of said
plenum chamber to engage said integral linked rows of tubes to
restrict movement of said bottom thin flexible sheet away from the
integral linked rows of tubes and towards the respective lateral
sides of said patient
mover air pallet. .Iaddend..Iadd.31. The patient mover air pallet
as claimed in claim 2, further comprising another thin flexible
sheet sealed to the top thin flexible sheet along the edges thereof
and sealed along lines extending transversely across said air
pallet to the top thin flexible sheet, including a perforated area
having a plurality of closely spaced small diameter pinhole-type
perforations opening upward towards the load for creating a second
air bearing, defining an upper plenum chamber directly beneath the
patient supported by said patient mover air pallet.
.Iaddend..Iadd.32. The patient mover air pallet as claimed in claim
31, wherein said upper plenum chamber, when pressurized from a
source of compressed air, provides sufficient lubrication for
patient positioning on the air pallet. .Iaddend..Iadd.33. The
patient mover air pallet as claimed in claim 31, wherein said upper
plenum chamber, upon pressurization from a separate source of
compressed air, can be utilized to supply a medicament in vapor
form upwards about the patient supported by the air pallet.
.Iaddend..Iadd.34. The patient mover air pallet as claimed in claim
8, further comprising another thin flexible sheet sealed to the top
thin flexible sheet along the edges thereof and sealed along lines
extending transversely across said air pallet to the top thin
flexible sheet, including a perforated area having a plurality of
closely spaced small diameter pinhole-type perforations opening
upward towards the load for creating a second air bearing, defining
an upper plenum chamber directly beneath the patient supported by
said patient mover air pallet. .Iaddend..Iadd.35. The patient mover
air pallet as claimed in claim 34, wherein said upper plenum
chamber, when pressurized from a source of compressed air, provides
sufficient lubrication for patient positioning on the air pallet.
.Iaddend..Iadd.36. The patient mover air pallet as claimed in claim
34, wherein said upper plenum chamber, upon pressurization from a
separate source of compressed air, can be utilized to supply a
medicament in vapor form upwards about the patient supported by the
air pallet. .Iaddend..Iadd.37. The patient mover air pallet as
claimed in claim 8, wherein at least one of said tubes constituting
said semi-rigid backing member carries said air inlet means at one
end thereof opening directly thereto, and wherein at an opposite
end thereof, an air flow port opens to an integral linked tube of
another row of tubes to permit flow of low pressure air flow from
one tube of one of said rows to said tube of another row via said
air flow port and wherein the cross-sectional area of said air flow
port is substantially less than the cross-sectional area of said
air inlet means such that said one tube of said one linked row is
at a higher pressure than said other tube of said another linked
row of tubes. .Iaddend..Iadd.38. The patient mover air pallet as
claimed in claim 8, wherein openings are provided within said tubes
of one row which open directly into tubes of the adjacent row, and
wherein said tubes of said one or said adjacent row have further
openings which open directly into the plenum chamber, and wherein
at least one of said tubes of one of said rows carries air inlet
means at one end thereof opening directly thereto, such that said
patient mover air pallet constitutes a flow through soft pad with
said flow of air being through said tubes of integral linked rows,
and through said plenum chamber to effect said means for
substantially restricting lateral shrinkage of the plenum chamber,
while providing simultaneously said air film. .Iaddend..Iadd.39.
The flexible air pallet as claimed in claim 17 wherein said
flexible backing chambers are sealed from said plenum chambers, and
means are provided for separately supplying compressed air to said
backing chambers from that supplied to said plenum chambers.
.Iaddend..Iadd.40. The flexible air pallet as claimed in claim 39,
further comprising a pressure relief valve operatively coupled to
said flexible backing chambers and set to prevent the pressure
therein from reaching a level inducing capillary closure of the
patient supported by said patient mover air pallet.
.Iaddend..Iadd.41. The flexible air pallet as claimed in claim 40,
wherein said pressure relief valve is a variably adjustable valve
such that said flexible backing chambers can be lightly air
pressurized to form a highly supple comfortable air mattress for
supporting a patient thereon over long periods of time without
trauma, while providing therapy to said patient. .Iaddend..Iadd.42.
The flexible air pallet as claimed in claim 17, wherein at least
one of said tubes constituting said semi-rigid backing surface
carries said air inlet means at one end thereof opening directly
thereto, and wherein at an opposite end thereof, an air flow port
opens to an integral linked tube of another row of tubes to permit
flow of low pressure air flow from one tube of one of said rows to
said tube of another row via said air flow port and wherein the
cross-sectional area of said air flow port is substantially less
than the cross-sectional area of said air inlet means such that
said one tube of said one linked row is at a higher pressure than
said other tube of said another linked row of tubes.
.Iaddend..Iadd.43. The flexible air pallet as claimed in claim 17,
wherein openings are provided within said tubes of one row which
open directly into tubes of an adjacent row, and wherein said tubes
of said one or said adjacent row have further openings which open
directly into said at least one plenum chamber, and wherein at
least one of said tubes of one of said rows carries air inlet means
at one end thereof opening directly thereto, such that said air
pallet constitutes a flow through soft pad with said flow of air
being through said tubes of linked rows, and through said plenum
chamber to effect said means for substantially restricting lateral
shrinkage of the plenum chamber, while providing simultaneously
said air film. .Iaddend..Iadd.44. The flexible air pallet as
claimed in claim 17, wherein said rows of tubes generally extend
longitudinally along the air pallet. .Iaddend..Iadd.45. The
flexible air pallet as claimed in claim 17, wherein said rows of
tubes generally extend laterally across the air pallet.
.Iaddend..Iadd.46. The flexible air pallet as claimed in claim 17,
further comprising means for eliminating trauma to the head and
neck of a patient supported on the air pallet induced by jolts
received from unequal air pressurization of the row of tubes
forming the flexible backing chambers. .Iaddend..Iadd.47. The
flexible air pallet as claimed in claim 46, wherein said means for
eliminating trauma to the head and neck of a patient comprises air
flow paths between the ends of the tubes and the opposing edge of
the air pallet, said air flow path having a pre-determined minimum
dimension. .Iaddend..Iadd.48. The flexible air chamber-type air
pallet as claimed in claim 24, wherein said means for rendering
said backing surface rigid comprises at least one row of tubes with
each tube of said row of tubes having a common wall with said at
least one plenum chamber, said common walls of said tubes, under
pressurization, rendering said at least one row of tubes rigid
under said
load to stably support said load thereon. .Iaddend..Iadd.49. The
flexible air chamber-type air pallet as claimed in claim 23,
wherein said means for limiting shrink of the air pallet comprises
two integral, linked vertical rows of tubes with a first row being
laterally offset with respect to a second row such that the centers
of the tubes in the first row are aligned with abutting peripheries
of tubes of the second row and adjacent tubes of said two rows
having a common wall under pressurization to opposite sides being
rendered taut and rigid, wherein said rows of tubes comprising a
series of backing chambers, and means for coupling said thin,
flexible sheet underlying the backing surface to another thin,
flexible sheet intermediate said bottom thin, flexible sheet and
said backing surface, which defines with said backing surface the
series of backing chambers, at spaced positions substantially
across the extent of said area of perforations to provide
individual segments to said at least one plenum chamber to prevent
excessive slack in said bottom thin, flexible sheet.
.Iaddend..Iadd.50. The flexible air chamber-type air pallet as
claimed in claim 48, wherein said at least one row of tubes is
sealed from said at least one plenum chamber, and means are
provided for separately supplying compressed air to said at least
one row of tubes from that supplied to said at least one plenum
chamber. .Iaddend..Iadd.51. The flexible air chamber-type air
pallet as claimed in claim 50, further comprising a pressure relief
valve operatively coupled to said at least one row of tubes and set
to prevent the pressure therein from reaching a level inducing
capillary closure of the patient supported by said air pallet.
.Iaddend..Iadd.52. The flexible air chamber-type air pallet as
claimed in claim 51, wherein said pressure relief valve is a
variably adjustable valve such that said at least one row of tubes
can be lightly air pressurized to form a highly supple comfortable
air mattress for supporting a patient thereon over long periods of
time without trauma, while providing therapy to said patient.
.Iaddend..Iadd.53. The flexible air chamber-type air pallet as
claimed in claim 48, wherein at least one of said tubes
constituting said rigid backing surface carries said air inlet
means at one end thereof opening directly thereto, and wherein at
an opposite end thereof, an air flow port opens to an integral
linked tube of another row of tubes to permit flow of low pressure
air flow from one tube of one of said rows to said tube of another
row via said air flow port and wherein the cross-sectional area of
said air flow port is substantially less than the cross-sectional
area of said air inlet means such that said one tube of said one
linked row is at a higher pressure than said other tube of said
another linked row of tubes. .Iaddend..Iadd.54. The flexible air
chamber-type air pallet as claimed in claim 48, wherein openings
are provided within said tubes of one row which open directly into
tubes of an adjacent row, and wherein said tubes of said one or
said adjacent row have further openings which open directly into
the plenum chamber, and wherein at least one of said tubes of one
of said rows carries air inlet means at one end thereof opening
directly thereto, such that said air pallet constitutes a flow
through soft pad with said flow of air being through said tubes of
integral linked rows, and through said plenum chamber to effect
said means for substantially restricting lateral shrinkage of the
plenum chamber, while providing simultaneously said air film.
.Iaddend..Iadd.55. The flexible air chamber-type air pallet as
claimed in claim 48, further comprising means for eliminating
trauma to the head and neck of a patient supported on the air
pallet induced by jolts received from unequal air pressurization of
the row of tubes forming the flexible backing chambers.
.Iaddend..Iadd.56. The flexible air chamber-type air pallet as
claimed in claim 55, wherein said means for eliminating trauma to
the head and neck of a patient comprises air flow paths between the
ends of the tubes and the opposing edge of the air pallet, said air
flow path having a pre-determined minimum dimension.
.Iaddend..Iadd.57. The flexible air chamber-type air pallet as
claimed in claim 25, wherein said air pallet includes an
intermediate thin, flexible sheet interposed between said first
thin, flexible sheet and said second thin, flexible sheet which
with said first thin, flexible sheet defines a series of backing
chambers for supporting said load. .Iaddend..Iadd.58. The flexible
air chamber-type air pallet as claimed in claim 57, further
comprising a second intermediate thin, flexible sheet edge sealed
to said first intermediate thin, flexible sheet to opposite sides
thereof, and defining a backing member cavity, and wherein a
generally rigid backing member is carried within said cavity and
comprises part of said means for substantially restricting lateral
shrinkage of said plenum chamber over at least the width of said
perforated portion of said bottom thin flexible sheet.
.Iaddend..Iadd.59. The flexible air chamber-type air pallet as
claimed in claim 58, wherein said series of backing chambers are
sealed from said plenum chambers, and means are provided for
separately supplying compressed air to said series of backing
chambers from that supplied to said plenum chambers.
.Iaddend..Iadd.60. The flexible air chamber-type air pallet as
claimed in claim 59, further comprising a pressure relief valve
operatively coupled to said series of backing chambers and set to
prevent the pressure therein from reaching a level inducing
capillary closure of the patient supported by said air pallet.
.Iaddend..Iadd.61. The flexible air chamber-type air pallet as
claimed in claim 60, wherein said pressure relief valve is a
variably adjustable valve such that said series of backing chambers
can be lightly air pressurized to form a highly supple comfortable
air mattress for supporting a patient thereon over long periods of
time without trauma, while providing therapy to said patient.
.Iaddend..Iadd.62. The flexible air chamber-type air pallet as
claimed in claim 58, further comprising another thin flexible sheet
sealed to the top thin flexible sheet along the edges thereof and
sealed along lines extending transversely across said air pallet to
the top thin flexible sheet, including a perforated area having a
plurality of closely spaced small diameter pinhole-type
perforations opening upward towards the load for creating a second
air bearing, defining an upper plenum chamber directly beneath the
patient supported by said air pallet. .Iaddend..Iadd.63. The
flexible air chamber-type air pallet as claimed in claim 62,
wherein said upper plenum chamber, when pressurized from a source
of compressed air, provides sufficient lubrication for patient
positioning on the air pallet. .Iaddend..Iadd.64. The flexible air
chamber-type air pallet as claimed in claim 62, wherein said upper
plenum chamber, upon pressurization from a separate source of
compressed air, can be utilized to supply a medicament in vapor
form upwards about the patient supported by the air pallet.
.Iaddend..Iadd.65. The flexible film air chamber-type air pallet as
claimed in claim 26, wherein said flexible, generally planar
backing surface is comprised of at least a top thin, flexible sheet
and a bottom thin, flexible sheet being sealed to each other and
defining a series of flexible backing chambers directly overlying
said at least one plenum chamber. .Iaddend..Iadd.66. The flexible
film air chamber-type air pallet as claimed in claim 65, wherein
said means for preventing hotdogging and load instability, for
maintaining said backing surface generally parallel to said
developed air film, for limiting shrink of the air pallet, and for
rendering said backing surface sufficiently rigid during air
pressurization of said at least one plenum chamber comprises at
least two integral, linked vertical rows of backing chambers with a
first row being laterally offset with respect to a second row such
that the centers of the chambers in the first row are aligned with
abutting peripheries of chambers of the second row and adjacent
chambers of said two rows having a common wall under pressurization
to opposite sides being rendered taut and rigid and means for
coupling said thin, flexible sheet underlying the backing surface
to said backing chambers at spaced positions substantially across
the extent of said area of perforations to provide individual
segments to said at least one plenum chamber to prevent excessive
slack in said bottom thin, flexible sheet. .Iaddend..Iadd.67. The
flexible film air chamber-type air pallet as claimed in claim 65,
wherein said series of backing chambers are sealed from said plenum
chamber, and means are provided for separately supplying compressed
air to said series of backing chambers from that supplied to said
at least one plenum chamber. .Iaddend..Iadd.68. The flexible film
air chamber-type air pallet as claimed in claim 67, further
comprising a pressure relief valve operatively coupled to said
series of backing chambers and set to prevent the pressure therein
from reaching a level inducing capillary closure of the patient
supported by said air pallet.
.Iaddend..Iadd.69. The flexible film air chamber-type air pallet as
claimed in claim 68, wherein said pressure relief valve is a
variably adjustable valve such that said series of backing chambers
can be lightly air pressurized to form a highly supple comfortable
air mattress for supporting a patient thereon over long periods of
time without trauma, while providing therapy to said patient.
.Iaddend..Iadd.70. The flexible film air chamber-type air pallet as
claimed in claim 65, wherein at least one of said backing chambers
constituting said backing surface carries said air inlet means at
one end thereof opening directly thereto, and wherein at an
opposite end thereof, an air flow port opens to an integral linked
chamber of another row of backing chambers to permit flow of low
pressure air flow from one chamber of one of said rows to said
chamber of another row via said air flow port and wherein the
cross-sectional area of said air flow port is substantially less
than the cross-sectional area of said air inlet means such that
said one chamber of said one linked row is at a higher pressure
than said other chamber of said another linked row of backing
chambers. .Iaddend..Iadd.71. The flexible film air chamber-type air
pallet as claimed in claim 65, wherein openings are provided within
said backing chambers of one row which open directly into backing
chambers of the adjacent row, and wherein said chambers of said one
or said adjacent row have further openings which open directly into
the plenum chamber, and wherein at least one of said backing
chambers of one of said rows carries air inlet means at one end
thereof opening directly thereto, such that said air pallet
constitutes a flow through soft pad with said flow of air being
through said backing chambers of integral linked rows, and through
said plenum chamber to effect said means for substantially
restricting lateral shrinkage of the plenum chamber, while
providing simultaneously said air film. .Iaddend..Iadd.72. The
flexible film air chamber-type air pallet as claimed in claim 65,
wherein said series of backing chambers generally extend
longitudinally along the air pallet. .Iaddend..Iadd.73. The
flexible film air chamber-type air pallet as claimed in claim 65,
wherein said series of backing chambers generally extend laterally
across the air pallet. .Iaddend..Iadd.74. The flexible film air
chamber-type air pallet as claimed in claim 26, further comprising
another thin flexible sheet sealed to the generally planar backing
surface along the edges thereof and sealed along lines extending
transversely across said air pallet to the backing surface,
including a perforated area having a plurality of closely spaced
small diameter pinhole-type perforations opening upward towards the
load for creating a second air bearing, defining an upper plenum
chamber directly beneath the patient supported by said patient
mover air pallet. .Iaddend..Iadd.75. The flexible film air
chamber-type air pallet as claimed in claim 74, wherein said upper
plenum chamber, when pressurized from a source of compressed air,
provides sufficient lubrication for patient positioning on the air
pallet. .Iaddend..Iadd.76. The flexible film air chamber-type air
pallet as claimed in claim 74, wherein said upper plenum chamber,
upon pressurization from a separate source of compressed air, can
be utilized to supply a medicament in vapor form upwards about the
patient supported by the air pallet. .Iaddend..Iadd.77. The
flexible film air chamber-type air pallet as claimed in claim 65,
further comprising means for eliminating trauma to the head and
neck of a patient supported on the air pallet induced by jolts
received from unequal air pressurization of the series of flexible
backing chambers. .Iaddend..Iadd.78. The flexible film air
chamber-type air pallet as claimed in claim 77, wherein said means
for eliminating trauma to the head and neck of a patient comprises
air flow paths between the ends of the tubes and the opposing edge
of the air pallet, said air flow path having a pre-determined
minimum dimension. .Iaddend.
Description
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 flow exemplified by U.S.
Pat. No. 3,948,344 entitled. "LOW COST PLANAR AIR PALLET MATERIAL
HANDLING SYSTEM" issued Apr. 6, 1976, and U.S. Pat. No. 4,272,856
entitled, "DISPOSABLE AIRBEARING PATIENT MOVER AND VALVE EMPLOYED
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 defining 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 face 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 perforated flexible sheet.
In all 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 jack the load above the flexible sheet prior to the
creation of the frictionless air bearing and to insure the ability
of the air pallet to ride over surface 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.
Pat. No. 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. Pat.
No. 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 flexible 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
flowthrough 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 the intermediate sheet and the bottom sheet with the
bottom sheet bearing the pattern of perforations over the foot
print of the load. U.S. Pat. No. 4,528,704 issued to Jack Wegener
and Raynor D. Johnson, co-applicants herein on July 16, 1985 and
entitled .[.Semi-Rigid Air Pallet Type Patient Mover.].
.Iadd.SEMI-RIGID AIR PALLET TYPE PATIENT MOVER .Iaddend.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
subject matter of U.S. Pat. No. 4,417,639 issued to Jack Wegener, a
co-applicant herein on Nov. 29, 1983 entitled, "DYNAMIC GAS
PRESSURIZED JACKING STRUCTURE WITH IMPROVED LOAD STABILITY AND AIR
PALLET EMPLOYING SAME". Further, as evidenced in FIG. 10 thereof,
such jacking structure may be formed totally of thin flexible 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. Pat. No.
4,686,719 .[.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 perforated area of the thin flexible bottom sheet. The patient
may be bound to the top of the patient mover via a pair of crossed
VELCRO.RTM. hook and loop material 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 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
patient 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 time 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
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 pallettype patient movers have generally
employed a rigid backing member starting with U.S. Pat. No.
3,948,344. Exceptions lie in the patient mover of U.S. Pat. No.
4,272,856, and in the patient mover illustrated in FIGS. 4 and 5 of
U.S. Pat. No. 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 and 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 the 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.
If the mass of the load is through 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 flexible
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 "jacking" 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.
The term "pillowing" describes the ability of the thin, flexible
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 backing
member will ground out against the thin, flexible bottom sheet and
the surface 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 surface
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, flexible sheet material such as a
bag, the bag will take a circular cross-section when fully
pressurized, the true essence of a balloon.
Where the thin, flexible bottom sheet is tightly mounted at
opposite sides to the generally rigid backing member that rigid
backing member functions to control jacking, pillowing and
ballooning. Where the rigid 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, flexible bottom sheet. Excessive slack leads to
ballooning.
Other means have been provided for controlling pillowing, such as
the lamination of additional members to a center 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 vertical from face to face,
control the degree of pillowing. The load itself may act as a
pillowing control means. The insertion of a rigid plate internally
within a thin, flexible bag acts both as a rigid backing member, a
pillowing control means and under certain conditions air
distribution means for insuring air pressurization 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 valving or gating of the air flow system entering the plenum
chamber and creating the air bearing, and the stiffness or
flexibility of the material used in forming the thin, flexible
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. Pat. No. 4,272,836 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. Pat. No. 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, 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.
Pat. Nos. 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.]. .Iadd.makes .Iaddend.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 flexible pad to eliminate the rigid backing member
by or substituting an all-flexible sheet material structure for
such rigid backing member, FIGS. 4 and 5 of U.S. Pat. No. 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 led to the
development of stacked tubes, one functioning as a pure jacking
chamber, and the second as a combined jacking 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 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. Pat. No.
4,417,639.
In air chamber-type air pallet patient movers as exemplified by
FIGS. 4 and 5 of U.S. Pat. No. 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 .[.common.]. .Iadd.commonly
.Iaddend.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' FIG. 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 200 of the drawings. This structure conforms to FIG. 4 of
U.S. Pat. No. 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 surface 212. Each of the transverse
seal lines 214 joining the top and intermediate sheets 202, 204,
together forming individual compressed air pressurizable chambers
or tubes 216, function as hinging areas between adjacent 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 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 FIGS. 4 and 5 of U.S. Pat. No. 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 under severe conditions a loss
or reduction in effective plenum chamber air film or air bearing
footprint print 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, FIG. 2, is of a given width W when flat
and deflated, the tendency of such plenum chamber is to have that
width W reduced to W the diameter of the tube when full inflated,
as seen by a comparison with FIG. 3.
Another phenomenon which occurs utilizing the air chamber-type air
pallets of FIGS. 4 and 5 of U.S. Pat. No. 4,528,704 is a lack of
rigidity of the air chamber assembly defined by the top 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 FIG. 4
of U.S. Pat. No. 4,528,704 or the flow-through tubes 80 of the FIG.
5 embodiment of that patent, the line connections between abutting
sides 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, FIG. 1. Further, .[.while.]. the presence of a load
such as a patient and the weight thereof, depressing the upper
surface of the air pallet FIG. 1 (corresponding to FIGS. 4 and 5 of
U.S. Pat. No. 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 FIGS. 4 and 5 of U.S. Pat. No. 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, (1) 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 flowing through the
various chambers of the thin, flexible sheet structure.
Further, in operation of the air chamber type air pallets, FIGS. 4
and 5 of U.S. Pat. No. 4,528,704, 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
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 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
FIG. 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.
FIG. 2 is a sectional view of a single tube prior to air
pressurization thereof.
FIG. 3 is a sectional view of the tube of FIG. 2 illustrating
lateral shrinkage thereof upon air pressurization.
FIG. 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.
FIG. 5 is a vertical sectional view of the air pallet of FIG. 4,
under air pressurization.
FIG. 6 is an end view of the air pallet of FIGS. 4 and 5 during
placement partially beneath the patient and under air
pressurization.
FIG. 7 is a similar end view to that of FIG. 6 during initiation of
patient transfer, partially supporting the patient.
FIG. .[.7.]. .Iadd.8 .Iaddend.is a further end view, similar to
that of FIGS. 6 and 7, with the patient fully supported by the air
pallet.
FIG. 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 two flexible sheet air
chamber-type patient mover air pallet of FIGS. 4 and 5.
FIG. 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.
FIG. 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.
FIG. 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.
FIG. 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.
FIG. 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.
FIG. 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.
FIG. 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.
FIG. 17 is a schematic top plan view of a further two-sheet
flexible film air chamber-type patient mover air pallet of the
present invention.
FIG. 18 is a schematic top plan view of a modified form of air
chamber-type patient mover air pallet of the present invention.
FIG. 19 is a schematic vertical sectional view of a modified form,
simple two-sheet flexible film air chamber-type patient mover air
pallet of the present invention prior to air pressurization of the
tubular chambers thereof.
FIG. 20 is a schematic vertical sectional view of the air pallet of
FIG. 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.
FIG. 21 is a schematic vertical sectional view, on an enlarged
scale, of the air pallet of FIG. 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.
FIG. 22 is a similar view to that of FIG. 21, illustrating the
flattening of the tangential contact portion of the tubes with the
underlying support surface and the resultant air bearing created
thereby.
FIG. 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.
FIG. 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.
FIG. 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 plenum chambers incorporated therein.
FIG. 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.
FIG. 27 is a top plan view of the top, thin, flexible sheet of the
air pallet of FIG. 26.
FIG. 28 is a top plan view of the first intermediate, thin flexible
sheet of the air pallet of FIG. 26.
FIG. 29 is a top plan view of the second intermediate, thin
flexible sheet of the air pallet of FIG. 26.
FIG. 30 is a top plan view of the bottom, thin flexible sheet of
the air pallet of FIG. 26.
FIG. 31 is a schematic, vertical sectional view of the assembly of
the four sheets for the air pallet of FIG. 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 FIG. 26.
FIG. 32 is a perspective view, partially cut away, of the air
pallet of FIG. 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.
FIG. 32a is a perspective view, partially cut away, of the air
pallet of FIG. 32, modified to form a flow through single air
source type air pallet.
FIG. 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.
FIG. 34 is a top plan view of a first intermediate, thin, flexible
sheet of the air pallet of FIG. 33.
FIG. 35 is a top plan view of one of dual second intermediate, thin
flexible sheets of the air pallet of FIG. 33.
FIG. 36 is a top plan view of a bottom thin, flexible sheet of the
air pallet of FIG. 33.
FIG. 37 is a schematic, vertical sectional view of the air pallet
of FIG. 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.
FIG. 38 is a perspective view, partially broken away, of the air
pallet of FIG. 33 under air pressurization and illustrating the
extent of hot dogging of that air pallet.
FIG. 39 is a schematic, vertical sectional view of a modified air
chamber-type patient mover air pallet of FIG. 26, forming yet a
further embodiment of the invention.
FIG. 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 FIG. 39.
FIG. 41 is a schematic, vertical sectional view of yet a further
flexible sheet air chamber-type patient mover air pallet of the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention in the various embodiments described in
detail hereinafter takes into account the parameters discussed
within the Background Of 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 invention 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 log rolling, and possibility of
severe spinal cord injury to the patient.
Referring to FIGS. 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-side parallel chambers 306. The individual
chambers or tubes 306 which tend as per FIG. 5 to take a circular
cross-section when air pressurized via a source 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.].
.Iadd.two-ply .Iaddend.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,
FIG. 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 310 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 movement of the patient.
Upon air pressurization of plenum chambers 306, the patient is
jacked to some extent, an air bearing is created at A, FIG. 6,
between the folded over halves of the patient mover air pallet 310,
and the patient P is caused to move up onto the imperforate upper
thin, flexible sheet 302, FIGS. 6, 7. The patient can then be moved
back onto a gurney, backboard B or the like, with or without
environmental control sheets, FIGS. 7, 8 as support equipment, and
as needed or desired.
By gently inflating 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 FIG. 9, and comparing that figure to the result
of inflation of a flat, deflated single chamber body, FIGS. 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, FIG. 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 FIG. 4, is significantly larger
than the width W'of the single inflated chamber 220, FIG. 3, whose
diameter D when fully inflated is approximately two-thirds of its
flat, deflated width W, FIG. 2. Note that the diameter D' of each
chamber 306 in FIG. 9 is significantly smaller than the diameter D
of the single chamber 220 structure when inflated. FIG. 3.
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, FIGS. 10, 11 and 12 are
exemplary of seal lines forming parallel flow paths from a single
air inlet. In FIG. 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 FIG. 11 a singular flow 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 FIG. 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
pallet 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).
FIGS. 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 FIG.
13, compressed air, as indicated by arrow 714, enters inlet 712 for
parallel flow 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
superpositioning of air pallet 310, FIG. 4, on a large circle C to
form a chamber 220 equivalent to that of FIG. 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, flexible 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 FIG. 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, FIG. 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, FIG. 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 significantly 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 chambers, which in turn provides
the ability of the air pallet to support the load P. In addition,
FIG. 15 represents a further phenomenon or operating parameter
ascertained by the applicants. Instead 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 bearing the perforations, flatten to form small footprint
areas corresponding to the large circle C footprint X of FIG. 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.
FIG. 16 is a rendition of an X-Y coordinate structure and depiction
of what occurs in FIG. 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, FIG. 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 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, FIG. 15.
The aspects discussed above, particularly with respect to FIGS. 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 surface
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 .pi.. From FIGS. 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 direction, 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 such tube
arrangement performs an anti-shrink action.
FIG. 17 illustrates schematically, a two-sheet air pallet similar
to that shown in FIG. 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 flow entering inlet 312 from a
compressed air source 314 flowing transversely across the air
pallet 310 to the side opposite the inlet 312 and with parallel air
flows through the individual tubes 306 of the tube array.
FIG. 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 914 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 tubes 906 to
opposite sides thereof, all receiving compressed air from a single
source 914. In all of the embodiments of the invention using two
thin flexible sheets, the multiple 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 simplification 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, FIG. 4.
Reference to FIGS. 19 and 20 show a modification of the basic
two-sheet air pallet 310 of FIG. 4. In this case, the air pallet
310' otherwise corresponding to that of FIG. 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 FIG. 20, and thus cradle a
patient P. With air 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,
FIG. 20. If, as shown, the lower sheet has excess material
accumulated between the joined lines compared to the upper sheet,
then upon inflation 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 FIG. 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
fixed support surface 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
FIG. 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,
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 by 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 flat
area as possible for each of the tubes 306 along the fixed planar
support surface 311, to obtain maximum lift. If the perforated 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
hereinafter, 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 lubrication 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.
An important 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 achieved 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 filling 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 FIG. 4 and in
accordance with variations thereof, through FIG. 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 FIG. 23, an air chamber-type
patient mover air pallet, indicated generally at 1010 is formed of
a thin, flexible upper or top sheet 1002 physically separate from a
thin, flexible bottom sheet 1004, but linked by vertical
imperforate stringers 1022 which are sealed or otherwise joined at
opposite 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
hole-type perforations 1016 to form air bearing or air film A
between the bottom thin, flexible sheet 1004 and the generally
fixed underlying support planar surface 1011. Stringers 1022 form
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 FIG. 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 308 joining the top and bottom sheets 302, 304 of the
embodiment of 310, FIG. 4. To the contrary, by utilizing stringers
or vertical walls .[.102.]. .Iadd.1022 .Iaddend.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.
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.degree. apart on their circumference, when
inflated, will form a rigid member between the attachment area,
i.e., a common wall which resists hinging and which functions as an
I-beam.
In accordance with the embodiment of FIG. 23, which in all other
respects is similar to the embodiment of FIG. 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 merely air backing chambers.
Turning next to FIG. 24, a further embodiment of the invention is
indicated generally at 1110. In this embodiment, which again is a
variation of the embodiment of FIG. 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
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 backing chambers or jacking
chambers since they function to jack the load and act similar to
the generally rigid backing member of U.S. Pat. No. 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 FIG. 24 an air inlet tube
1112 receives compressed air from a source indicated by the arrow
1114 with this air first 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, flexible 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
chambers 1130 are at spaced transverse positions defined 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
film A relative to the footprint of the load P (patient).
Additionally, the air pallet of FIG. 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 patient 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
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 FIG. 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 flow 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 jointed commonly to the thin,
flexible intermediate sheet 1222 at uniform locations transversely
across its width, as by seal lines 1238. Secondly, there 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 antishrink construction via the common walls of
the upper row of chambers 1230. It is noted that some of the ports
1234 extend 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 of 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 FIGS. 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 FIG. 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, FIG. 26. Sheets 12, 14, 16 and
18 of rectangular plan configuration are all of the same length but
only sheets 12.[...]..Iadd., .Iaddend.16 and 18 are of the same
width. Intermediate sheet 14 may be somewhat narrower for purposes
which will be apparent hereinafter. In creating the assembly, the
purpose of stacking is to form individual sealed chambers or tubes
which extend 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
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. Pat. No. 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.times.100 denier 3.0 ounce square yard waterproof,
vapor-permeable nylon twill. One side may be coated with ZEPEL.RTM.
waterproof coating by DuPont and an appropriate anti-static agent.
The other side may be coated with approximately 11/4 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 using linear
heat application (under appropriate backing) on respective sides of
the multilayer flexible sheet array. For the embodiment of FIGS.
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
FIG. 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 FIGS.
27 and 31 at positions laterally offset from the thermal bond seal
lines 28 between sheets 16 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 FIG. 27 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 FIGS. 26
through 32 inclusive relates to the air pallet of FIG. 4 of U.S.
Pat. No. 4,528,704. In that respect, the top sheet 12 is provided
with .[.a.]. .Iadd.an .Iaddend.input or intake valve indicated
generally at 36, FIG. 26, which may be a normally closed flap type
air intake valve conventional to this art. Such valve is shown
schematically at 36 in FIG. 26 and FIG. 31. In order to effect a
constant pressure, compressed air pressurization of the tubes,
upper section 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 provided
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.
Upon air inflation, as seen in FIG. 32, by the lateral offsetting
of the tubes of adjacent rows of tubes by the intermediate spacing
of seal lines 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 footprint 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, FIG. 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. Pat. No. 4,528,704, FIG. 2.
Alternatively, a flap type inlet valve 72' to the opposite side,
FIG. 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.RTM. cooperative mating hook and loop type fastener strips
such as those set forth in U.S. Pat. No. 4,686,719, at 78 and
80.
It should be appreciated that for the air pallet of FIG. 4 of U.S.
Pat. No. 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)
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.
The air pallet 10 of the present invention is 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 FIGS.
26-32, and as shown particularly in FIG. 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 FIGS. 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, FIG. 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, 52. An air input valve .[.72.]. .Iadd.72"
.Iaddend.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 FIG. 32 includes a central perforated area 24'
which mirrors that at 24 of the bottom sheet 18. An air 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 for valve 82). This is particularly desirable where
the air pallet 10 functions as an operating room 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
(patient or inanimate object) relative to an underlying generally
planer fixed support surface. Such air pallet includes means
forming a flexible generally planar 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 means are operatively associated with the at
least one plenum chamber to ensure air flow 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 plenum chamber to jack
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
balloning. 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 of chambers and
said at least one flexible chamber of the lower row of chambers.
Air inlet means 72, .[.82.]. .Iadd.72' .Iaddend.function to
pressurize said chambers to cause said at east one common member to
become rigid and to thereby render said flexible, generally 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 has 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 flexible load, the
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 flexible
chambers.
FIG. 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' has like elements to that of air 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 flow 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 FIGS. 33-38, inclusive, a further embodiment of the
present invention in the form of a flow through soft pad or bladder
type air pallet 10" is shown. The air pallet 10" is formed
similarly to that of the embodiment of FIGS. 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 FIG. 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
extention. 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.
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 FIG. 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
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 FIG. 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 flow 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 FIG..]. 10 as shown in
FIG. 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 well as the
perforated area 24 of each bottom sheet 18 for the respective
embodiments. The size 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 trunk, 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 FIG. 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 FIGS. 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 FIG. 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 FIG. 34, 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 14 to the top thin flexible sheet 12. In order to
effect that action, it is preferable to insert a backing anvil
positioned beneath the thin 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
backing 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, FIG. 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 FIG.
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 12 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, FIG. 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 chamber
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 pallet 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 unequal
air pressurization through parallel tubes with head jolt upon lift
during jacking of the patient due to air flow through the row of
tubes forming flexible backing chambers defined by three of the
four sheets 12, 14, 16 upon air pressurization. In FIG. 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 FIG. 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 FIG. 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 72,
schematically illustrated as a relatively small diameter tube in
FIGS. 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 flow 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.
Unlike the embodiment of FIG. 26, the patient mover type air pallet
10" of FIGS. 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. Pat. Nos. 4,272,856
and 4,528,704. These valves automatically self seal when not in use
so that the valves 71, 72' may be alternatively 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 flexible sheet formed soft
pad air pallet 10" 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 is
not produced since the gas pressurization is uniform in
development, and equal for respective tubes of the upper row tube
array, 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. FIG. 38 shows the severe actions of hot
dogging 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. Pat. Nos. 3,948,844 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 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.
FIG. 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, FIG. 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 FIG. .[.40.]. .Iadd.39, .Iaddend.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 FIG. 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 generally
rigid upon air pressurization. Additionally, the bottom thin
flexible sheet 18 over the extent of the lateral perforated area
beating perforations 26, forms a series of adjacent 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..].
.Iadd.29'.Iaddend., FIG. 40, may be inserted within backing member
cavity 27, FIG. 39, whose longitudinally extending, laterally
spaced beams .[.41a.]. .Iadd.29'a .Iaddend.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.]. .Iadd.29'.Iaddend. opening and strung on the frame by
tensioned cords with the frame providing an exterior anti-shrink
function.
Turning next to FIG. 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 FIG. 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 64, inclusive and the plenum chamber. While the dual tube
array in FIG. 41 corresponding to FIG. 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 FIG. .[.26.]. .Iadd.32.Iaddend., 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.
* * * * *