Note: Descriptions are shown in the official language in which they were submitted.
ii2~:
This invention relates to inflatable supports, such
as air mattresses, for use in air beds More specifically,
the present invention relates to an improved air mattress of
the type described in applicant's copending Canadian patent
application Serial No. 467,284, filed November 7, 1984.
Air mattresses are used with cots and beds to provide
yieldable body supports The air mattresses are air-filled
bags having flexible air impervious sheet members secured
together to form one or more longitudinal chambers for
accommodating air under pressure. Air mattresses have air
inlet tubes that are used with hand-operated pumps, bag pumps,
and other sources of air under pressure to inflate the
mattresses. Plugs are used to close the tubes after the
mattresses are inflated with air Conventional air ~attresses
do:not have pressure relief valves so that they can be easily
over-inflated, causing rupture of the mattress material or
the separation of the seams. An over-inflated air mattress
is relatively hard and can become misshaped and wobbly.
The invention is a fluid accomodating apparatus or
mattress providing a support for a body, such as a human
body. The mattress preferably accommodates air under pressure,
such as 1 psi or less. A pressure relief valve is operable
to insure that the air pressure is maintained below a pre-
determined value so as not to over-inflate the mattress. The
mattress is adapted to be coupled to a pump means operable
to provide a supply of air under pressure to the mattress and
allow air to exhaust from the mattress. The mattress has
top and bottom walls that are connected together with side
walls and end walls to form an enclosed air impervious chamber.
The chamber is divided into a plura:Lity of connected transverse
gas accommodating passages with a plurality o~ beams or
webs. Each web is joined to the -top and bottom walls and
the side walls and functions to limit outward expansion of the
walls. An air inlet means secured to one of the walls is
useable to facilitate the supply of fluid under pressure into
the passages.
Accordingly, the present invention relates to an
air mattress accommodating air under pressure for providing a
body support comprising a top wall, a bottom wall spaced from
and loca~ed below the top wall, side walls and end walls
secured to said top and bottom walls, all of said walls
comprising flexible air impervious sheet members sealed together
along the edge portions thereof to form a chamber for
accommodating gas under pressure, seam means securing adjacent
portions of the sheet means together, a plurality of support
means located in said chamber extended between said side walls
and secured to said top and bottom walls providing transverse
passages accommodating air and limiting outward expansion of
the top and bottom walls when air under pressure is stored in
said chamber, each of said support means having a web section
and opposite end portions secured to said side walls to limit
outward expansion of the side walls when air pressure is stored
in said chamber, each of said end portions having at least one
opening allowing air communication between said transverse
passages, tube means mounted in the seam means to facilitate
supplying air under pressure into said chamber, and air
pressure relief valve means mounted in the seam means open to
said chamber and atmosphere, said valve means having a cylindrical
body secured to the seam means, body having a passage open to
said chamber and atmosphere, an annular plug having a center
J'~5
hole located within said passage in engagement with said bod~,
valving means located in said passage engageable with said
plug to close said passage, said valving means including a
rod having an outer end extended through said center hole, a
head joined to said outer end of the rod engageable with the
plug to close said center hole and a member mounted on the rod;
and spring means engageable with said plug and member to bias
said head in sealing engagement with said plug to maintain
the pressure of air in said chamber, said spring means having
a biasing force that allows the head to move away from the
plug when the pressure of air within the chamber exceeds a
selected ma~imum limit whereby air is vented from said chamber.
In the following description of the drawings and of
the preferred embodiment of the invention, applicant's
earlier envention is described first.
Figure 1 is a perspective view o~ an air mattress
having an air pressure relief valve;
Figure 2 is an enlarged top plan view of the mattress
of Figure l;
Figure 3 is an enlarged foreshortened sectional view
taken along the line 3-3 of Figure 2;
Figure 4 is an enlarged sectional view taken along
the line 4-4 of Figure 3;
Figure 5 is an enlarged sectional view taken along the
line 5-5 of Figure 2;
Figure 6 is an enlarged sectional view taken along
the line 6 6 of Figure 2;
Figure 7 is an enlarged plan view of a portion of
the top of the apparatus;
Figure 8 is an enlarged sectional view taken along
the line 8-8 of Figure 5;
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Figure 9 IS a perspective view of a modification of
the air mattress of Figs. 1 to 8;
Figure 10 is an enlarged foreshortened sectional view
taken along the line 10-10 of Figure 9;
Figure 11 is an enlarged foreshortened sectional
view taken along the line 11-11 of Figure 9;
Figure 12 is an enlarged sectional view taken along
the line 12-12 of Figure 9.
Figure 13 is a perspective view of a preferred
embodiment of an air mattress in accordance with the present
invention;
Figure 14 is an enlarged top plan view of the air
mattress of Figure 13;
Figure 15~is an enlarged foreshortened sectional view
taken along the line 15-15 of Figure 14;
Figure 16 is an enlarged top plan view of a portion
of the air mattress of Figure 14;
Figure 17 is an enlarged foreshortened sectional view
taken along the line 17~17 of Figure 14;
Figure 18 is a sectional view taken along the line
18-18 of Figure 14;
Figure 19 is an enlarged portion of the outside end
of the air mattress and pressure relief valve; and
Figure 20 is an enlarged sectional view taken along
the line 20-20 of Figure 19.
Referring to Figures 1 and 2, there is shown a fluid
accommodating air mattress having an air pressure relief
valve indicated generally at lC useable to yieldably support
an object. Apparatus 10 accommodates a compressible fluid,
such as air, to yieldably support an object in a horizontal
position. The apparatus is preferably an air mattress,
or bladder used in an air bed to yieldably support one or more
prone persons.
Air mattress 10 has a generall~ rectangular top ~lall
11 located over a rectangular bottom wall 12. Side walls
13 and 1~ and end walls 16 and 17 are secured to the outer
peripheral edges of top and bottom walls 11 and 12. Upper
and lower continuous peripheral seals 18 and 19 join the
adjacent edges of walls 11 - 14 and 16 and 17. Seals 18
and 19 are ultrasonic fluid imper~ious connections that per-
manently join peripheral adjacent portions of walls 11 - 14
and 16 and 17 together. Seals 18 and 19 are lap seams forming
the outer peripheral ed~es of the air mattress.
As shown in Figures 3 and 5, a plurality of laterally
spaced transverse internal webs or beam supports 21 linearly
extend between side walls 13 and 14. Each support 21 has
a body or web section and opposite end portions. The upper
edges of the web sections of supports 21 have lips 23 that
are secured to the inside surface of upper wall 11. The
lower portions of the web sections have lower lips 24 that are
secured to the inside surface of bottom wall 12. Seals 25
are utilized to secure lips 23 and 24 to the upper and lower
walls 120 Seals 25 extend transversely across top and bottom
walls 11 and 12 and terminate in enlarged ends 25A.
As shown in Figure 7, each end 25A has an enlarged
tear drop shape spaced inwardly from adjacent side walls 13
and 14 to provide air passages 28 and 33. The enlarged ends
25A strengthen the ends of each seal. Webs 21 are flexible,
non-elastic sheet members ~hat prevent the upper and lower
walls 11 and 12 from ballooning or bulging outwardly. Webs
f"
21 divide the interior of apparatus 10 into a plurality of
transverse fluid accommodating passages or chambers 22.
Chambers 22 extend transversely across apparatus 10 and are
located side-by-side between the end walls 16 and 17.
S As shown in Figures 1 and 2, transverse webs 21 are
equally spaced from each other along the longitudinal dimension
or length of air mattress. Adjacent webs 21 provide separate
transverse gas passages or chambers 22. Adjacent webs 21
are preferably laterally spaced about 10 cm. Other lateral
dimensions between adjacent webs 21 may be used. Webs 21
vertically reinforce top and bottom walls 11 and 12 and restrict
outward expansion or bulging of these walls. Webs 21 also
laterally reinforce the opposite side walls 13 and 14 and
restrict outward expansion of these walls. All of webs 21
cooperate with the top, bottom, and side walls 11, 12, 13,
14, 16 and 17 to retain the box shape of air mattress 10.
Referring to Figure 3, intexnal support 21 has a first
end portion 26 terminating in a right angle turned ear 27.
The ear 27 is secured by an ultrasonic seal to the mid-portion
of side wall 13. Openings 28 and 29 are located adjacent
upper and lower sides of end portion 26 to permit gas to
flow into the end of an adjacent chamber 22. The opposite
end of support 21 has a second end portion 31 terminating in
a right angle turned to ear 32. Ear 32 is secured to the
mid portion of end wall 14. Openings 33 and 34 located on
opposite sides of second end portion 31 allowing gas to flow
into the end of an adjacent air chamber Z2. The first and
second end portions 26 and 31 retain side walls 13 and 14
in generally upright positions when the pressure of the gas
in the chambers 22 is increased. Each of supports 21 has
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end portions that are secured to middle portions of the side
walls 13 and 14.
As shown in Figure 5, a generally horizontal end sup-
port or rib 36 is provided with lips 37 and 38. Lip 37 is
secured to the mid-portion of end wall 16. Lip 38 is secured
to the adjacent internal support 21. The horizontal support
retains end wall 16 in a yenerally upright position, as sho~7n
in Figure 1. The opposite end of air mattress 10 has a
g~nerally hori20ntal support (not shown) that is identical to
support 36 to retain end wall 17 in a generally vertical position.
As shown in Figure 4, side wall 13 is a ~abric plastic
sheet member comprising an outer fabric layer 39 and an inner
plastic layer 41. The layers 39 and 41 are integrally
joined together to form an air impervious wall. Seal 42 joins
ear 27 to the mid-portion o~ side wall 13. The side wall can
be a Nylon vinyl, polyester vinyl, or Rayon vinyl. These
materials are flexible, strong, and air impervious. They also
do not deteriorate over time and are water-resistant.
Re~erring to Figures 1 and 6, a plug tube assembly
indicated generally at 43 is secured to one end of the end
wall 16. Assembly 43 is used as an inlet passageway to allow
gas to flow into chambers 22. The gas can be derived from a
pump, such as an air pump or blower. Assembly 43 comprises
a short tube 44 having a head 46. A washer 47 surrounding
tube 44 is loca~ed adjacent the outside of wall 16 and is
secured thereto with head 46 to join assembly 43 to end wall
16. The outer end of tube 44 is closed with a removable plug
48. The tube 44 can be connected with a suitable hose to an
air pump, air blower, or a like source of air under pressure.
Suitable valves (not shown) can be used to regulate the supply
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~ ~ $ ~J~
of air under pressure that is carried via tube 44 into chambers
22 of air mattress 10 and exhaust air therefrom.
~ n air control system for an air bed is disclosed in
co-pending Canadian Patent Application Serial No. 467,~84.
This air control s~stem has a pump and hand-operated switches
for regulating valves and the pump to supply air to air
mattresses. The air control system can be used to supply air
to apparatus 10.
As shown in Figures 1, 5, and 8, a one-way air pressure
relief valve 49 mounted on end wall 16 prevents ovex-inflation
of air mattress 10, which can cause wall rupture and seam
separation. Referring to Figure 8, valve 49 has a flexible
boot 49~ supporting a valve body 49B. Boot 49A and valve body
49B are attached to the inside of end wall 16, thereby locating
the valve within chamber 22. Valve body 49B is a tubular member
accommodating a movable spring biased valving member, as shown
in Figure 20, operable to open the valve and allow air to flow
from chamber 22 to the atmosphere when air pressure in chamber
22 reaches a predetermined value. For example, when the air in
chamber 22 reaches a pressure of 1 psi or greater, the valving
member will move to the open position thereby venting air from
chamber 22 to the atmosphere and reducing the air pressure
within the mattress. When the air pressure drops below the
maximum value, such as 1 psi, the valve will automatically
close. This prevents over-inflation of air mattress 10 and
separa~ion of the seams and bursting of the walls thereof.
The pressure relief characteristics of valve 49 can be selected
to provide for a desired maximum pressure of air in chamber 22
of air mattress 10. For example, valve 49 is operable to
limit the pressure of air within air mattress 10 to about
-- 8
~$~
1 psi.
Referring to Figures 7 - 10, there is shown a modifica-
tion of the air mattress of the invention indicated generally
at 50. Air mattress 50 is commonly termed an air bag or air
bladder used to yieldably support one or more persons in an
aix bed.
Air mattress 50 has a flexible generally rectangular
top wall 51 located over a bottom wall 52. Opposite side
walls 53 and 54 and end walls 56 and 57 join the peripheral
edges of the top and bottom walls 51 and 52. A continuous
upper peripheral seal 58 joins the outer peripheral edge of
upper wall 51 to the top edges of the side walls and end
walls 53 ~ 57. The outer peripheral edge of bottom wall 52
is secured with a continuous lower peripheral seal 59 to the
lower edges of the side wall and end walls 53 - 57. The
- seals 58 and 59 are continuous air impervious seals so as
to maintain the air under pressure within air mattress 50.
The inside of air mattress 50 has a plurality of pairs
to transverse internal supports 61 and 62 providing the top
and bottom walls 51 and 52 and side walls 53 and 54 with
support to minimize the outward expansion or bulging of these
walls as a resul-t of the pressure of the gas within air mattress
50. Supports 61 and 62 divide the inside of apparatus 50 into
a plurality of transverse gas accommodating chambers 65.
Chamhers 65 extend between side walls 53 and 54. Air mattress
50 has a series of side-by-side passages that extend from the
front end wall 56 to the rear end wall 57.
As shown in Figure 8, internal support 61 has a gener-
ally flat beam having an upper lip 63 secured by a seal or
the like to the inside of top wall 51. A lower lip 69 is
_ 9 _
secured by a seal to the inside of the lower wall 52. Support
61 has a plurality of holes 66. The holes 66 allow support
61 to expand in a generally vertical or upright direction so
thak the air pressure within chamber 65 causes the top and
bottom walls to expand outwardly. This provides the top and
bottom walls 51 and 52 with a plurality of outwardly convex
curved portions or a tuffed shape. Walls 51 and 52 have a
tuffed shape when gas under pressure is stored in the apparatus.
Supports 61 and 62 comprise pairs of weblike members that
are evenly spaced along the length of the apparatus~ As shown
in Figure 9, eight pairs of supports 61 and 62 are incorporated
in apparatus 50. Support 61 has an end portion 67 terminating
in an ear 68. The ear 68 is secured to the mid-section of
side wall 53. Openings 69 and 71 are located above and below
end portion 67 and allow gas to flow into adjacent chamber 65.
Holes 66 also allow air to flow between adjacent chambers.
Support 61 has a second end portion 72 terminating in a lip 73.
Lip 73 is secured to the mid-section of side wall 54 to prevent
the side wall from bulging outwardly when subjected to air
under pressure. The openings 74 and 76 located above and
below end portion 72 allow gas to flow into the adjacent
chamber 65.
As shown in Figure 11, the internal support 62 has a
web member or beam extending between the top and bottom walls
51 and 52. Support 62 is laterally spaced from support 61
to form a transverse gas chamber. A lip 77 secures the top
of support 62 to the inside of top wall 51. In a similar
manner, a lip 78 secures the bottom of support 62 to the
inside of bottom wall 52. Support 62 has a plurality of
holes 79. Holes 79 are laterally offset from holes 66 in
-- 10 --
support 61. Portions of the top and bottom walls 51 and 52
adjacent the holes 79 bulge outwardly providing the top and
bottom walls with shallow convex-shaped portions that are
laterally offset from convex-shaped portions formed by holes 66
and support 61. Support 62 has a first end portion 80
terminating in an ear 81. Ear 81 is secured by sonic welds or
the like to the mid-portion of side wall 53. Openings 82 and 83
adjacent the upper and lower portions of end portion ao alIow gas
to flow into adjacent chamber 65. The opposite end of support 62
has a second end portion 84 terminating in an ear 86. Ear 86 is
secured to the mid-portion of side wall 54. Openings 87 and 88
are adjacent upper and lower sides of end portion 84 and allow
gas to flow into the chamber 65. Holes 79 also allow gas to flow
to adjacent chambers.
15Referring to Figure 12, a generally horizontal end
support or web 89 extends along the mid-section of end wall 56.
Support 89 has a pair of lips 91 and 92 secured to the inside:of
end wall 56 and the first transverse support 61. Support 89
holds end wall 56 in a generally vertical position when the
apparatus is inflated with gas. An identical end support (not
shown) is secured to the inside of the mid-section of the end
wall 57 to maintain its generally vertical shape.
A plug valve assembly 93 is attached to one end of wall
~ : 56. Valve assembly 93 is identical to the valve assembly 43
: :: 25 shown in detail in Figure 6. An elongated flexible tube can be
. :used to connect the valve assembly 93 to a source of air under
:
:pressure, such as an air pump. An example of an air pump and air
: control system is shown in my Canadian Patent No. 1,24~5,379,
which issued on November 22, 1983.
: 30
,
Apparatus 50 is provided with a one-way gas pressure
relief valve 94. Valve 94 is mounted on the inside of end
wall 56. Alterna-tively, valve 94 can be located in the seam
59, similar to valve 138 shown in Figures 19 and 20. The
valve 94 functions to relieve and regulate the maximum air
pressure in the mattress. When the pressure exceeds a pre-
determined limit, such as 1 psi, valve 94 will open to evacuate
air from the air mattress. This prevents over-inflation of
the apparatus and eliminates the seam separation and bursting
of the walls thereof.
Examples of air mattresses are as follows:
The air mattresses are made in different sizes, i.e.,
twin, full, queen, and king. These mattresses have a width
from 39 inches (99 cm) to ~4 inches (213 cm). The mattress
has a thickness of 4 inches (10 cm) and transverse internal
web space 4 inches (10 cm) apart along the length thereof.
The walls and webs are made of Nylon vinyl sheet material.
An ultrasonic sealing and vulcanization processes are used
to make the airtight seams. The air mattress has a high
degree of stability, as the air moves transversely in
passages 22 when a body rests on top wall 11. Only a controlled
restricted amount of air moves longitudinally. The air
mattress has a rectangular box shape with generally flat
sides and ends. The air mattress fits in the dish support
of an air bed. An air pressure relief valve is secured to an
end wall of the air mattress. The valve is located within
the chamber of the air mattress so that outside objects, such as
mattress covers, bed s~ructures, and the like do not interfere
with the operation of the valves. The valve has a spring
biased valving member operable to open the valve when the
2,~
pressure of the air in the air mattress exceeds 1 psi. The
valving member automatically closes when the air pressure in
chamber falls below 1 psi.
Re~erring to Figures 13 and 14, there is shown an
air mattress with an air pressure relief valve in accordance
with the present invention indicated generall~ at 100. Air
mattress 100 accommodates a compressible fluid, such as air,
to yieldably support one or more persons in a horizontal or
prone position. Preferably, apparatus 100 is an air mattress,
used in an air bed to yieldably support one or more prone
persons. Apparatus 100 has an air pressure relief valve 138
opera~le to limit the internal air pressure to about 1 psi
to prevent mattress blow-out.
Air mattress 100 has a generally rectangular top wall
101 located over an identical bottom wall 102. Side walls
103 and 104 and end walls 106 and 107 extend between the
top and bottom walls 101 and 102 to complete the outer structure
of the air mattress. The top wall 101 and side walls 103, 104
and end walls 106, 107 have a continuous upper peripheral
edge 108 that are joined together to form a gas impervious
seal. In a similar manner, the bottom wall 102 is joined to
the side walls 103, 104 and end walls 106, 107 with a lower
outwardly directed peripheral edge 109~ As shown in Figures
15 and 18, a continuous strip 111 located in the inside of
air mattress 100 is positioned over the seam of the upper
peripheral edge 108. A strip 111 located inside air mattress
100 is located over the seam of the lower peripheral edge
109. The strips 111 and 112 are vulcanized to their adjacent
walls to reinforce the seams of edges 108 and 109.
As shown in Figures 15, 17 and 18, the walls 101,
c~
102, 103, 104, 106 and 1~7 are fabric and plastic sheets
comprising an inner plastic layer 113 and an outer ~abric layer
114. Layers 113 and 114 are integrally joined together to
form air impervious walls. Plastic layer 113 may be a Nylon
S vinyl, polyester vinyl or Rayon vinyl. These materials are
strong, flexible, air impervious, water resistant, and do
not deteriorate over time. Fabric layer 114 is a soft fabric,
such as cotton or a synthetic fabric, bonded to the outside
surface of layer 113.
The rectangular shape of air mattress 100 is maintained
when inflated with air under pressure by a plurality of
laterally spaced transverse internal ribs or beams 116. Beams
116 linearly extend between side walls 103 and 104. The upper
and lower portions of beams 116 have lips 117 and 118 that
are secured to top and bottom walls 101 and 102, respectively.
As shown in Figure 7, the seams formed by the lip 117 terminate
in tear drop end portions 119 inwardly from outer edge 108
of top wall 101. End portions 119 strengthen the ends of the
seals joining beam 116 to top and bottom walls 101 and 102.
Beam 116 has central ears 121 and 122 at the opposite ends
thereof secured to the side walls 103 and 104, respectively.
Beams 116 are flexible, non-elastic sheet members that prevent
the upper and lower walls 101 and 102 from ballooning or bulging
outwardly. Beams 116 also divide the interior chamber of air
mattress 100 into a plurality of transverse air accommodating
passages or chambers 124. Chambers 124 extend transversely
acros~ the air mattress and are located side-by-side along
the entire length of the air mattress. Openings 123 in each
of the corners of transverse beams I16 provide passages for
the flow of air into and out of adjacent chambers 124. Holes
- 14 -
;t~
can be placed in beams 116, such as holes 66 and 79 sho~m
in Figures 10 and 11 to provide the top and bottom of mattress
with a rounded or tuffed convex curved structure. The adjacent
beams 116 are preferably laterally spaced from each other
about 10 cm. Other lateral dimensions between beams 116
may be used. Beams 116 form vertical and horizontal rein-
forcement for the top and bottom walls and side walls of the
air mattress so that the air mattress retains a generally
box shape as shown in Figures 13 and 14 when inflated with air.
Referring to Fiyure 18, a generally horizontal rib
126 located in the center of the end chamber 124 is secured
to the end wall 106 and adjacent beam 116. Rib 126 rein-
forces and maintains the generally vertical shape of end
wall 106 when the air mattress is inflated. A similar
horizontal rib (not shown) is located in the opposite end of
the air mattress to reinforce and maintain the vertical shape
of end wall 107.
As shown in Figures 13 and 17, air mattress 100 is
connected to an air blower 132 operable to supply the air
mattress with air under pressure and allow air to exhaust
from the air mattress. A tube 127 is located in the seam
of the lower peripheral edge 109. Tube 127 is a plastic
tubular member that is vulcanized to bottom wall 102 and end
wall 106 ~orming the lower peripheral edge 109. Tube 127
has a passage 128 open to chamber 124 and a hose 129. Hose
129 fits over the outer end o~ tube 127 and is secured thereto
with a ring clamp 131. The opposite end of hose 129 is located
about an air outlet tube 134 of air blower 132. A ring clamp
133 holds hose 129 on air outlet tube 134, The air blower
132 has an electric motor (not shown) coupled to a source o~
- 15 -
electric power with a plug 136. A three-position switch 137 is
used to control the operation of the electric motor. The motor
drives a fan or impeller that moves air under pressure to hose
129, tube 137 and into air mattress chamber 124. A person lying
S on the air mattress 12~ can utilize switch 137 to operate the air
blower to increase the pressure of the air in the air mattress or
cause the air in the mattress to be evacuated to atmosphere. An
air control system for an air bed is disclosed in my Canadian
Patent No. 1,245,379, issued November ~2, 1988. This air
controlled system including its pump and valves can be used to
supply air under pressure to the air mattress 100.
As shown in Figures 13, 19 and 20, a one-way pressure
relief valve, indicated generally at 138, is incorporated in the
lower peripheral lO9o The entire valve 128 is located within the
confinement of edge 109. The operation of the pressure relief
valve is not affected by outside structures, such as mattress
covers, bed frames, and the like. Valve 138 operates under all
positions of the mattress to maintain a predetermined maximum air
pressure in air mattress chamber 124. Preferably, the maximum of
air pressure is about 1 psi. An air pressure exceeding 1 psi
will open the pressure relief valve 138 allowing air to exhaust
to atmosphere thereby relieving the pressure of the air within
chamber 124. Air mattress 100 can be used with the pressures
below 1 psi. The air blower 132 is used to supply the air under
pressure to the mattress. Hand control 137 is used to control the
exhaust o~ air from the mattress and thereby control the pressure of
- 16 -
,7,~:J~ii,..,7
the air ~ithin the mattress.
Pressure relief valve 138 has a cylindrical plastic
body 139 having a cylindrical surface 141. The outer surface
149 is secured by vulcanization to plastic layers 113 of the
bottom wall 102 and end wall 106 forming the lower pheripheral
edge 109. Body 139 is permanently secured to plastic layers
113. Body 139 has a linear passage 142 accommodating a plug
143. Plug 143 fits into the outer end of passage 142 with a
friction fit and holds an annular seal 144 in engagement with the
inside of body 139. Plug 143 has a central hole 146 accommodating
a linear rod 147. Rod 147 has as its outer end a cylindrical
head 148 having an outer peripheral groove 149. An O-ring
151 fits into groove 149 and engages an annular inclined seat
152 surrounding the outer end of hole 146. Seat 152 is in
an outer annular portion of plug 143. Rod 147 extends through
hole 146 toward mattress chamber 124. A cup member 153 is snapped
onto the inner end of rod 42. Cup member 153 has a plurality
of circumferentially spaced ears 156 which allow air to flow
past cup member 153 through passage 142. A coil spring 154 is
interposed between ears 156 and seal 144 to continuously bias
the O~ring 151 into sealing engagement with annular seat 152.
- When the pressure of the air in the mattress chamber 124
exceeds the biasing force of spring 154, head 148 will move
outwardly thereby moving O-ring 151 away from seat 152 opening
passage 146. The air flows past head 148 to atmosphere
relieving the pressure of the air in the chamber 124. Valve
138 automatically prevents over inflation of the air mattress
and the separation of the seams and the flow-out or bursting
of the walls 102, 103, 104, 106 and 107. Head 148 is always
located within passage 142 of tube 139 so that outside structures,
- 17 -
such as mattress covers, bed frames, and the like do not
interfere with the operation of the valve. The pressure
relief characteristic of valve 138 is determined by selecting
the biasing force of spring 154 to provide a desired maximum
pressure of the air in chamber 124. For example, when the
biasing orce of spring 154 is equal to 1 psi the valve 138
will open when the pressure of the air in chamber 124 exceeds
1 psi.
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