Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02303643 2000-03-31
TITLE OF THE INVENTION= THERMO-ACOUSTIC INSULATION SYSTEM FOR
SANITARY DEVICE
FIELD OF THE INVENTION
The present invention relates to sanitary devices such as bathtubs, shower
stalls, whirlpool baths and the like, and more particularly to a thermo-
acoustic insulation
system for such sanitary devices.
BACKGROUND OF THE INVENTION
It is known to provide thermal insulation for bathtubs, whirlpool baths or
spas, as shown in US patent No. 5,345,621 issued in 1994, inventor D.R.
Livingston. The
purpose of this insulation is to prevent the water temperature inside the tub,
during use, from
dropping too fast, which alternately requires the tub to be filled again with
warmer water if
no heater is provided, or the heater to spend more energy heating the water,
if a heater is
provided.
The Livingston patent shows that the bathtub shell comprises a rigid
fiberglass
layer, provided on its interior surface with a smooth acrylic coating, and on
its outer surface
with an urethane foam insulation layer. The tub is installed in a wood skirt
or podium
structure, which spacedly surrounds the shell and on which the shell upper
downtumed
peripheral edge rests. Livingston also discloses the use of an insulation
blanket 30 which,
as shown in figure 3 of the Livingston patent, forms an inverted dome to
completely enclose
the shell, spacedly therefrom. Thus, an air pocket is formed between the shell
and the
1
CA 02303643 2000-03-31
insulating blanket which promotes enhanced insulation for the whirlpool tub.
The insulating blanket of the Livingston patent is made from a multiple-layer
plastic film (e.g. including air bubbles therein), provided with a sheet of
aluminum or the like
reflective metallic foil on the inner surface thereof, in spaced facing
register with the
urethane foam coating of the tub shell. It is known that the metallic foil
will promote
reflection of the heat irradiating from the tub back towards the tub.
A problem with the spa disclosed in the Livingston patent, is that its single
insulating air pocket is not sufficient to prevent significant temperature
loss of the water.
Indeed, the urethane foam layer is not efficient enough to prevent the water
from loosing its
energy therethrough, and even the insulating blanket is not efficient enough
to prevent the
water temperature to drop at a significant rate at room temperature.
Furthermore, the
Livingston tub provides a fluid-tight air pocket between the tub shell and the
insulating
blanket which, under the important temperature gradients present on one side
of this air
pocket in the tub water and on the other side of this air pocket in the
ambient air, will
promote important condensation and humidity accumulation in the air pocket.
This high
humidity percentage and condensation in this pocket is likely to result in
mould formation,
and the urethane foam is effectively likely to degenerate and rot over time,
thus becoming
less efficient, in addition to any hygiene problems which may result
therefrom.
A further problem with prior art whirlpool tubs such as the Livingston tub,
is that the noise emitted by the whirlpool tub, with its water pump, is at a
high level.
It is noted that the problems noted hereinabove, occur not only in whirlpool
2
CA 02303643 2007-06-01
bathtubs, but also in spas, ordinary bathtubs, shower stalls, therapeutic
tubs, and the like.
The so-called therapeutic tubs are similar to whirlpool bathtubs, but include
air jets injected
in the water, instead of water jets. Some tubs combine both water and air
jets. Throughout
the present specification, reference will be made to sanitary devices as
including all of the
above-mentioned devices.
OBJECTS OF THE INVENTION
It is an object of the invention to provide a thermal insulation system for
sanitary devices.
It is another object of the present invention to provide an acoustic
insulation
system for sanitary devices.
It is yet another object of the invention to provide a thermal insulation
system
which helps prevent humidity formation in the tub casing or podium.
SUMMARY OF THE INVENTION
The present invention relates to an insulation system for use in a sanitary
device of the type including a rigid shell mounted inside a rigid podium
structure resting on
the ground and peripherally surrounding the sanitary device, said insulation
system
comprising:
- a first insulating membrane, destined to be installed peripherally about the
sanitary
device shell and spacedly therefrom inside the podium structure, so as to form
a first
3
CA 02303643 2007-06-01
closed air pocket between the sanitary device shell and said first insulating
membrane; and
- a second insulating membrane, destined to be installed peripherally about
said first
insulating membrane and spacedly therefrom inside the podium structure, so as
to
form a second closed air pocket between said first and second insulating
membranes;
wherein said first and second air pockets and said first and second insulating
membranes
provide enhanced thermal and acoustic insulation to the sanitary device.
Preferably, said system further includes condensation control elements in said
first and second air pockets.
Preferably, said condensation control elements are air circulation channels
provided on or about said first insulating membrane, for allowing limited air
circulation
between said first and second air pockets through and/or about said first
insulating
membrane.
Preferably, said air circulation channels are perforations provided throughout
said first insulating membrane.
Preferably, said first insulating membrane is destined to loosely hang from
the sanitary unit structure, said air circulation channels further including
spaces about said
first membrane allowing limited air circulation between said first and second
air pockets
around said first insulating membrane.
Preferably, said first membrane comprises an inner reflective metallic foil
fixedly mounted on a synthetic felt backing.
Preferably, said metallic foil is aluminum.
4
CA 02303643 2007-06-01
Preferably, said second insulating membrane is a mineral wool blanket.
The present invention further relates to an insulation system for use in a
sanitary device of the type including a rigid shell mounted inside a rigid
podium structure
resting on the ground and peripherally surrounding the sanitary device, said
insulation
system comprising a first closed pocket member at least partly surrounding the
sanitary
device, a second closed pocket member surrounding said first pocket member, a
first
insulating membrane mounted between said first and second air pockets, and a
second
insulating membrane mounted outwardly of said second air pocket, thus creating
a two-step
thermal and acoustic insulation of the sanitary device.
The present invention further relates to a whirlpool-type bathtub assembly,
including:
- a tub resting on the ground and having a shell defining an upper open mouth
and an
inner enclosure destined to be filled with warm water;
- a rigid podium structure resting on the ground, peripherally surrounding
said tub
shell under said open mouth;
- a first pocket member located peripherally around said tub under said open
mouth
and inside said podium structure, defining a first closed air pocket located
between:
(a) said tub shell; (b) the ground; and (e) a first insulating membrane
attached to the
podium structure and spaced from said tub shell;
- a second pocket member, located peripherally around said first pocket
member, and
defining a second closed air pocket located between: (a) said first insulating
5
CA 02303643 2000-03-31
membrane; (b) the ground; (c) said podium structure; and (d) a second
insulating
membrane located spacedly and peripherally outwardly of said first insulating
membrane;
wherein said first and second pocket members allow for thermal and acoustic
insulation of
said tub while providing positive condensation control inside said podium
structure.
Preferably, said first insulating membrane comprises a reflective metallic
foil
fixedly mounted to a synthetic felt backing, said metallic foil including
perforations
therethroughout allowing limited air circulation through said first membrane
between said
first and second air pockets.
Preferably, said second insulating membrane is made from a mineral wool
blanket.
Preferably, said first insulating membrane is attached to said podium
structure
and loosely hangs therefrom to the ground, thus allowing limited air
circulation thereunder
between said first and second air pockets.
Preferably, said assembly further comprises vibration control pads spacing
said tub from the ground.
Preferably, said assembly further comprises either one of a water-pump
system, an air jet system, and the combination of a water pump and an air-jet
system, wherein
said either one of a water-pump system, said air jet system, and said
combination of a water
pump and an air-jet system is supported over ground by an anti-vibration pad.
The present invention further relates to a method for thermally and
6
CA 02303643 2000-03-31
acoustically insulating a whirlpool-type bathtub assembly of the type
comprising a tub having
a shell defining an upper open mouth and an inner enclosure destined to be
filled with warm
water, and a rigid podium structure resting on the ground and peripherally
surrounding said
tub shell under said open mouth;
said method comprising the following steps:
a) installing an outer insulating mineral wool blanket peripherally around
said tub shell
and spacedly therefrom and inside said podium structure;
b) installing inside said podium structure an inner insulating membrane
comprising an
inner metallic reflective foil sheet fixedly mounted on an outer synthetic
felt backing,
said inner insulating membrane being installed spacedly inwardly from said
outer
mineral wool blanket but spacedly outwardly from said tub shell so as to form
a first
air pocket between said tub shell and said inner insulating membrane, and a
second
air pocket between said inner insulating membrane and said outer mineral wool
blanket; and
c) fixedly attaching said inner insulating membrane to said podium structure
so that it
loosely hangs to the ground from an upper edge thereof to form a skirt
peripherally
outwardly spaced from said tub shell.
DESCRIPTION OF THE DRAWINGS
In the annexed drawings:
Figure 1 is a perspective view showing a whirlpool bathtub out of its podium,
7
CA 02303643 2000-03-31
the latter being partly cut-away to show the inner layers thereof, with the
thermo-acoustic
system according to the present invention;
Figure 2 is a view similar to figure 1, although without the bathtub, and
further showing how the insulating membrane can be fixed to the podium;
Figure 3 is a lateral cross-sectional elevation of the area III of figure 2,
further
showing the end portion of the bathtub shell and the water pump device;
Figures 4 and 5 are graphs showing water temperature gradients in a whirlpool
bathtub, for a non-insulated tub and a tub insulated with the system according
to the present
invention, for tubs devoid of and including a water heater system
respectively; and
Figures 6 and 7 are graphs showing acoustic pressure levels emitted by a
therapeutic tub and a whirlpool tub respectively, for conventional tubs and a
tub provided
with the insulating system according to the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
Figures 1 to 3 show a conventional whirlpool bathtub 10 including a rigid
shell 12 supported over ground by means of a pair of spaced-apart transverse
support bars
14, 16 resting on ground-bearing vibration-control pads 18. A rigid plate
member 20 is
installed between bars 14, 16 and shell 12, with a water pump system 22 being
provided on
a protruding end portion 20a of plate member 20. An anti-vibration pad 23 is
installed
between pump 22 and plate 20. As known in the art, water pipes 24, 26 will
convey the
water from pump 22 to inject the water through a number of nozzles 28
extending through
8
CA 02303643 2000-03-31
the tub shell 12, inside the tub hollow inner enclosure 30. An outlet port 32
allows the water
filled tub shell 12 to feed pump 22 with water, which is sucked up through an
outlet pipe 34
back into pump 22 to repeat the cycle. A drain hole 37a connected to a drain
pipe 37b allows
tub 10 to be selectively emptied. Tub shell 12 is provided with an upper
downturned
marginal edge portion 36.
As further known in the art, tub 10 is installed into the hollow central
opening
38 of a skirt or podium 40, e.g. made of wood, which rests on the ground. The
downturned
edge portion 36 of the tub shell 12 is destined to abut flatly on top of the
podium upper panel
42, the latter not having however any load-bearing role since tub 10 is
supported by pads 18.
A water-tight seal (not shown) is conventionally installed between the podium
upper panel
42 and the tub shell marginal edge portion 36 to prevent water spilled out of
tub shell 12 to
seep between shell 12 and podium 40.
Podium 40 includes a rigid frame structure 44 which can be formed of a
number of upright posts 46 spacing upper and lower horizontal struts 48 and
50. Outer
decorative panels (not shown) are usually provided on the peripheral outer
surface of frame
structure 44.
According to the present invention, there is provided inside podium 40, a
thermo-acoustic insulation system 52.
Insulation system 52 comprises a first insulating membrane 54 attached to the
upper edge of the podium upper panel 42 and which loosely hangs therefrom to
the ground.
Membrane 54 is formed of a reflective metallic foil on its inner side, fixedly
attached to an
9
CA 02303643 2000-03-31
outer synthetic felt backing or the like material. Preferably, the felt
backing comprises
polypropylene and polyethylene fibers. Such a membrane is of known
construction. The
metallic foil is preferably perforated all over its surface with very small
holes, such as would
be formed by piercing the foil with needle tips. As shown in figure 2,
membrane 54 can be
simply attached to the inner edge portion of podium upper panel 42 with a
conventional
fastener tool T, with membrane 54 then forming an inner skirt in podium 40.
Insulation system 52 is further provided with a conventional mineral wool or
fiberglass insulation blanket 56 which is peripherally installed spacedly
outwardly about
membrane 54. Blanket 56 can be simply installed in a self-standing fashion, or
alternately
can be attached to the frame structure 44 of podium 40.
According to the system of the present invention, there is provided a first
and
a second closed air spaces or air pockets 58 and 60, respectively between the
tub shell 12 and
insulating membrane 54, and between membrane 54 and the mineral wool layer 56,
as can
be well seen in figure 3. Furthermore, due to the loose hanging of membrane or
skirt 54 from
the inner edge of the podium upper panel 42 to ground level, and to the fact
that the foil of
membrane 54 is perforated, there is a fluid communication at a limited rate
which is allowed
between the first and the second air spaces 58 and 60. Thus, two concentric
annular air
pockets 58, 60 are present about the bathtub 10, with an insulation material
forming the outer
surface of each one of these air pockets 58, 60. The limited fluid
communication between
the first and the second air pockets 58, 60, with an insulating barrier 54, 56
being located
externally of both pockets 58, 60, allows a two step temperature gradient to
occur between
CA 02303643 2000-03-31
the bathtub water and the outer, ambient air. This, in addition to providing
enhanced
insulating properties to the whirlpool tub, advantageously helps to control
the humidity
inside podium 40. Tests have been done by the applicant on a bathtub according
to the
present invention, and the humidity control has been such that no condensation
at all has
occurred inside podium 40, which is of course highly desirable.
As shown, it is advantageous that the pump 22 and all the hot water
circulation pipes be entirely located inside the first air pocket 58, so that
this air pocket 58
take advantage of the heat emanating therefrom. The reflective foil helps to
maintain a warm
temperature inside the first air pocket 58, thus reducing significantly the
heat loss from the
water in tub 10.
The insulating membrane 54 has an inner reflective surface, for reflecting the
heat irradiating from the hot tub water through the tub shell 12 during use.
The outer felt
layer of membrane 54 will serve both for thermally and acoustically insulating
the bathtub
10. The outer mineral wool layer 56 also both thermally and acoustically
insulates tub 10.
Applicant has discovered that all the above-noted advantages of the thermo-
acoustic insulation system 52 according to the present invention, have yielded
positive and
unexpected results, both acoustically and thermally. These results can be
evaluated from the
graphs of figures 4 to 7 which show comparative characteristics of tubs
measured by
applicant in a controlled environment.
The graph of figure 4, with water temperature on the Y axis and the timeline
on the X axis, shows water temperature gradients measured in water located in
a
11
CA 02303643 2000-03-31
conventional, non-insulated whirlpool bathtub (curve 62), and for water
located in a
whirlpool bathtub insulated with the system according to the present invention
(curve 64).
No water heater is used in this case, and the water temperature is initially
measured at 97,8
F immediately after it has been poured to fill the tub. It can be seen that,
over an hour,
while the water in the conventional tub has dropped of 4 F, the water in the
insulated tub
has dropped only of 1.2 F. Thus only 33% of the water temperature decrease
from the
conventional tub, has occurred in the insulated tub. The effect of the tub
insulation is thus
significant.
The graph of figure 5, with same X and Y axes parameters as with figure 4,
shows water temperature gradients measured in water located in a conventional,
non-
insulated whirlpool bathtub provided with a water heater (curve 66), and for
water located
in a whirlpool bathtub insulated with the system according to the present
invention which is
not provided with a water heater (curve 68). It can be seen that for water
temperatures
initially measured at 100.4 F in the two tubs, the water temperature
variation over an hour
is small, i.e. in the case of the conventional heated tub, the water
temperature drops to 99,8
F; while with the tub insulated according to the system of the present
invention, the water
temperature drops to 99,6 F. Thus, over an hour, the water temperature
remains essentially
the same in the conventional, non-insulated, heated tub as in the non-heated,
insulated tub
of the present invention. Consequently, the insulation system of the present
invention could
render the water heating device obsolete where ambient temperatures remain
relatively warm
(approximately 70 F); while a tub subjected to cold temperatures, such as
whirlpool
12
CA 02303643 2000-03-31
bathtubs used outside in cold weather, would not require its water to be
heated as much.
It is noted that to obtain the results in both graphs of figures 4 and 5, the
ambient room temperature was regulated at 71.6 F +/- 1.0 F. Also, the water
temperature
curves have been slightly modified to provide the exact same initial
temperatures on both
curves. Indeed, water temperatures between two different tests could vary of
up to
approximately 1 F. To allow the comparative temperature values to be more
readily
appreciated from the graphs, the initial temperature difference between two
tests on a same
graph was added to each temperature value of the curve having the lowest
initial temperature.
The graph of figure 6, with sound intensity on the Y axis and sound wave
frequency on the X axis, shows three curves of the sound levels emitted by
operating
therapeutic bathtubs (i.e. with air jets) at different frequencies. The sound
originates mainly
from the air injection motors and the vibrations induced thereby in the tub
structure. Curve
70 represents the sound levels (in decibels) emitted by a first non insulated
conventional tub,
called conventional tub A; curve 72 is associated to a second non-insulated
conventional tub,
called conventional tub B; and curve 74 is associated to a tub insulated with
the system
according to the present invention. Conventional tub A is manufactured by the
present
applicant, and is similar to the tub used for the measurements of the
insulated tub, although
it lacks the insulation system of the invention. Conventional tub B is a tub
sold and
manufactured by another supplier of the therapeutic bathtub industry. It can
be seen that in
the wide range of sound wave frequencies where the measurements have been
made, the tub
according to the present invention emits significantly less sound than the
conventional tubs,
13
CA 02303643 2000-03-31
except in very low sound wave frequencies. This is especially true in light of
the fact that
the decibel scale is logarithmic, and thus a small change on the graph in the
number of
decibels emitted by a tub, results in a very important difference in the sound
level captured
by the human ear. The general sound level received by the human ear for each
tub, is as
follows: conventional tub A emits 73 dBA, conventional tub B emits 75 dBA, and
the
insulated tub according to the invention emits 53 dBA.
The graph of figure 7 is similar in X and Y axes parameters than that of
figure
6, but shows sound level measurements taken on operating whirlpool tubs (i.e.
with water
injection nozzles) instead of therapeutic tubs, at different sound wave
frequencies. The
sound emitted originates mainly from the water circulating motor and the
vibrations induced
thereby. The curve 76 represents the sounds emitted by a conventional tub C
manufactured
by the present applicant; the curve 78 represents the sounds emitted by a
conventional tub
D manufactured by another supplier of the whirlpool tub industry; and curve 80
represents
the sound emitted by the tub provided with the insulation system of the
present invention.
It can be seen again that the sound level of the tub insulated with the system
of the invention
is significantly lower than that of the conventional tubs. The general sound
level received by
the human ear for each tub, is as follows: conventional tub C emits 74 dBA,
conventional
tub B emits 71 dBA, and the insulated tub according to the invention emits 53
dBA.
It can thus be seen, from the comparative results obtained by testing a tub
equipped with the insulating system according to the present invention and
other
conventional tubs, that the insulation system according to the present
invention yields very
14
CA 02303643 2000-03-31
advantageous and highly unexpected results, both thermally and acoustically.
This is true
for all whirlpool-type tubs (i.e. whirlpool tubs, therapeutic tubs, and
combined water-jet and
air-jet tubs). It is further envisioned that other types of sanitary devices,
such as conventional
bathtubs, shower stalls and the like, be also equipped with the insulation
system according
to the present invention.
It is understood that any further modification to the present invention, which
does not deviate from the scope thereof, is considered to be included therein.
For example, although it is preferred that an inner insulating membrane
including a metallic foil mounted on a synthetic felt backing be used as the
inner membrane,
other inner insulating membrane could be used to achieve similar results.
Also, a second
suitable outer insulating membrane could also be used instead of the mineral
wool blanket
described in the present specification.
Furthermore, it is envisioned to provide different air circulation systems
between the first and the second air pockets 58, 60 located inside the podium
40. Small
pipes, or any other suitable communication devices could be used instead of
the first
membrane 54 being perforated and loosely hanging from the podium structure 44
to allow
limited air circulation between the first and second air pockets 58, 60.
