Note: Descriptions are shown in the official language in which they were submitted.
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The invention relates to a heat insulating shield
or screen or panel in particular for disposition between a
heating body or source and a body such as a wall and having
a surface facing the heating body or source which reflects
heat rays.
Reflective screens which radiate heat rays back
toward a heating body or toward the space to be heated
are known, However, their effectiveness is limited, since
they act only on the heat radiation and not on the other
heat losses. The dust carried by the hot air stream deposits
on the reflective surface, and the reflector screen quickly
loses its properties. It must be cleaned often which is
not always easy, particularly when the screen is inserted
between a heating body and the wall. The reflecting
surface of this known screen is unesthetic.
The object of the invention is to provide an improved
heat insulating shield or screen or panel.
The shleld, screen or panel of this invention has a
continuous sur:Eace with special protuberances which form air
deflecting members spaced in height and inclined toward the
source of heat, particularly in the vertical position of the
shield, screen or panel, so as to deflect gases which cir-
culate along the surface toward the heat source. A plurality
of smaller protuberances may also be formed on the protuber-
ances or facets.
The circulation of hot gases towards the body, par-
ticularly a cold partition or a wall, is prevented by the
reflective shield, screen or panel, and these gases which
flow along the shield, screen or panel are sent back by
the air deflecting members toward the heat source or radia-
tor or the space to be heated. The profile of the face of
the shield, screen or panel facing the heat source is advan-
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tageously sawtooth in form, and it is easy to understand
that each air deflecting member throws the stream back,
with the formation of a stagnant limiting layer in the
hollows of the surface, to constitute an insulating
cushion in front of the reflective surface of the shield,
screen or panel. This cushion limits the deposition of
dust on the reflecting surface, which retains its proper-
ties of reflecting the thermal radiation of the radiator.
According to a further feature of the invention,
the reflective shield, screen or panel is a stamped or heat-
shaped plate or sheet on which there is caused to appear,
on the rear face of the shield, screen or panel, opposed to
the reflecting surface, a conjugate profile which can block
the convective flow on this rear`face. This blocking effect
is accentuated when the shield, screen or panel is fixed
- against a wall, by the countercurrents created by the relief
of the`panel in the interval between the partition and the
shield, screen or panel, which is thus subdivided into a
great number of cells, ensuring good thermal insulation
without thermal contact bridges.
More specifically a preferred embodiment of the in-
vention includes a one-piece reflective heat insulating
thin sheet-like panel adapted to be positioned between a
source of heat and a substantially planar static support
structure to which the panel is attached adjacent its ends,
for limiting thermal exchange by radiation and by convection
between the source and the support structure. The panel is
spaced throughout the substantially its entire extent,
except at the points of attachment, a small distance from
the static support structure and defines a closed space
therebetween, and except for the point of attachment between
the static structure and the thin wall the entire length of
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the panel is substantially free of thermal bridges. The
one-piece wall has continuous interior and reflective
exterior surfaces of the same shape in longitudinal cross-
section defined by a plurality of outwardly extending
ledges and by a plurality of air deflecting members between
next adjacent pairs of the ledges. Each of the air deflect-
ing members is substantially longer than and extends out-
wardly from adjacent the base of a corresponding one of the
ledges and terminates adjacent the tip of the ledge next
adjacent to said one ledge.
The profile of the sheet confers sufficient rigidity
to the sheet even for a very thin sheet of plastic. The
~ fabrication and shaping of such a sheet are simple and
easy,`and the sheets can be compactly stacked for storage
and transportation. The reflective effect can be obtained by
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the panel is substantially free of thermal bridges. The
one-piece wall has continuous interior and reflective
exterior surfaces of the same shape in longitudinal cross-
section defined by a plurality of outwardly extending ledges
and by a plurality of air deflecting members between next
,~ adjacent pairs of the ledges. Each of the air deflecting
members is substantially longer than and extends outwardly
from adjacent the base of a corresponding one of the ledges
and terminates adjacent the tip of the ledge next adjacent
to said one ledge.
The profile of the sheet confers sufficient rigi-
dity to the sheet even for a very thin sheet of plastic.
The fabrication and shaping of such a sheet are simple and
easy, and the sheets can be compactly stacked for storage
and transportation. The reflective effect can be obtained
by coating or depositing on the sheet a layer having a high
reflecting power, for example, of aluminum. The profiled
sheet can be united to a planar support to form a self-
contained hollow cellular structure, which of course possesses
the properties mentioned above.
The reflective shield, screen or panel according to
the invention, particularly designed to be interposed between
a radiator and the adjacent wall where the parasitic losses
are considerable, can be utilized in any other location to
form a thermal screen, and in particular in air spaces formed
within walls or partitions, where it can advantageously
replace glass wool or porous plastic insulation. It more-
over has the advantage of being unaffected by moisture.
The described profile according to the present
improvement eliminates any mirror effect and lends itself
to decorative patterns. The panel can be semi-transparent
for example when it is to be placed in front of a window.
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Other advantages and characteristics of the inven-
tion will appear more clearly from the following description
of embodiments which are given by way of non-limiting example
and shown in the attached drawing, in which:
Fig. 1 shows a shield, screen or panel according to
the invention, placed between a heating body and a wall;
Fig. 2 shows an enlarged partial illustration of the
shield, screen or panel shown in Fig. l;
Fig. 3 shows a vertical section of a wall with a
shield, screen or panel inserted therein;
Fig. 4 is a perspective view of the shield, screen
or panel shown in Fig. 1,
Fig. 5 shows another embodiment of the shield, screen
or panel;
Fig. 6 is an enlarged perspective view of another
embodiment of the invention;
Fig. 7 is an enlarged perspective view showing a
plurality of shields, screens or panels stacked for shipping
or storage;
Fig. 8 shows the curves of temperature changes;
Fig. 9 shows an asymmetric panel of the invention
disposed horizontally,
Fig. 10 shows a symmetric panel.
In the Figures, a shield, screen or panel 10 is
interposed between a source of heat, particularly a central
heating radiator 12, and a dividing wall 14. The shield,
screen or panel 10 is formed by a continuous surface which
extends over the whole height of the radiator 12 and is
fixed by its edges 16, 18, for example by gluing, to the
wall 14, so as to form an air space 20 between the shield,
screen or panel and the wall 14. The surface of the shield,
screen or panel 10 has a sawtooth profile with air deflecting
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members 22 inclined in the direction of the radiator 12.
The face of the shield, screen or panel 10, oriented toward
the radiator 12, has considerable reflecting power and
incident radiation at 24 is reflected by the shield, screen
or panel 10 at 26 in the direction of the radiator 12 (see
Figure 2).
The shie~jd, screen or panel 10 can be a thin sheet,
as thin as paper, particularly of heat-shaped or stamped
plastic material, such as polyvinyl chloride so as to have
on its rear face, opposed to the reflecting face, a con-
jugate profile, the importance of which will appear more
clearly from the explanation of functioning, described with
reference to Figure 2. The convective streams of hot air,
shown by the arrows 28 in Figure 2, rise in the chimney formed
between the radiator 12 and the shield, screen or panel 10 and
are deflected in the manner indicated by arrows by the air
deflecting members 22, toward the radiator 12, with the
creation of a limiting layer 30 of stagnant air adjacent the
surface of the shield, screen or panel 10, and more parti-
cularly in the hollows of the sawtooth profile.
The shield, screen or panel 10 constitutes on the
one hand a screen preventing the flow of hot gases towards
the cold wall 14, and on the other hand a deflector sending
the hot gases rising in the chimney between the radiator and
the shield, screen or panel 10 back toward the location to be
heated. The limiting layer 30 of stagnant air prevents the
deposition of dust on the reflecting facets 22, which thus
retain their reflecting power. This limiting layer simul-
taneously provides a thermal screen between the hot gases
and the shield, screen or panel 10.
The effect of the sawtooth profile is seen from the
curves of temperature variation as a function of time given
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in Figure 8, in which curve I shows the variation in tempera-
ture of the surface of the wall in the absence of a reflective
shield, screen or panel 10, curve II shows the variation in
temperature of a flat reflective shield, screen or panel,
curve IV shows the variation in the temperature of the wall
with interposition of a reflective shield, screen or panel
with a sawtooth profile, of the type illustrated in Figure 2,
and curve III shows the variation of temperature at the level
of the shield, screen or panel 10 with a sawtooth profile.
The difference in temperature between curves II and III is
due to the front face, with inclined facets 22, modifying the
convective flow along the shield, screen or panel 10.
The conjugate profile on the rear face of the shield,
screen or panel 10 permits the space 20 formed between the
shield, screen or panel 10 and the wall 14 to be subdivided
into elementary spaces or cells, blocking the convective flow
in this space. Between the bottom of the teeth of the shield,
screen or panel 10 projecting in the direction of the wall 14
and the wall, there is a break in continuity which prevents
transmission by thermal conduction. This break in continuity
is bridged by a fluid screen represented by arrows 32 in
Figure 2. Inside the space 20, the hot gases rise and are
deflected by the substantially horizontal parts or ledges 34
of the sawtooth profile toward the wall 14, such that a
circular movement is formed for each cell corresponding to a
tooth of the profile. Each of the air deflecting members 22
is substantially longer than and extends radially outwardly
from adjacent the base of a corresponding one of the ledges
34. This b]ocking of convective counter flows in the space
20, which appears as a formation of thermally insulating air
cushions, improves the thermal insulation provided by the
shield, screen or panel 10. This improvement is clearly
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shown by curve IV of Figure 8, which shows the variation in
temperature of the wall 14 compared to the variation in
temperature of the shield, screen or panel 10, shown by
curve III.
The sawtooth profile confers sufficient rigidity
on the shield, screen or panel 10, to make it self-supporting
even when the shield, screen or panel is a single thin sheet
of heat-shaped or stamped plastic, such as polyvinyl chloride.
A perspective view of one of the shields, screens
or panels 10 is shown in Figure 4. As shown in Figure 7
because of their thinness and shape, the shields, screens or
panels 10 can easily be compactly stacked for storage or
transportation, and they can easily be fixed in place because
of their light weight.
The front face of the shield, screen or panel 10
can be coated with a layer of a material having a high
reflecting power, for example, with a layer of aluminum, or
can receive, for example by gluing, a thin sheet of aluminum.
The height of each tooth of the profile may be one or several
centimeters. The shield, screen or panel 10 can be made of a
translucent or transparent material, which is of particular
interest when a radiator is disposed in front of a window or
glazed partition, where the interposition of the shield,
screen or panel 10 should not reduce the illumination of the
room. The inclined facets 22 have in themselves a decorative
effect, which can be accentuated by any appropriate means.
The downward inclination of the facets 22 reduces the deposi-
tion of dust and prevents any reflection of luminous rays in
the direction of the room and any mirror effect which could
trouble the occupants.
Shields, screens or panels of the type shown in
Figure 4 have been constructed. Each panel has a total
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weight of 210 g/m2, a total thickness of about 1 cm, is approxi-
mately 12 cm wide and approximately 23.5 cm long and is divided
into 8 sections each forming a facet or protuberance 22. The
front face 22a of each protuberance is approximately 2.8 cm
long and the top face 22b is approximately .5 cm wide. Each
panel weighs approximately 7.5 g and is made of polyvinyl
chloride having a silver colored reflective surface, of vacuum
deposited aluminum.
Individual shields, screens or panels may be
assembled end to end and side to side to form larger shields,
screens or panels of any desired size.
Another embodiment of the invention is shown in
Figure 6. In that embodiment, a plurality of smaller protu-
berances 22', which can be for example 1/10 the size of the
protuberances 22, are formed on the protuberances 22. The
smaller protuberances 22' function to create small circular
air flow paths thereadjacent, as shown in Figure 6, from the
slow convection flow thereadjacent. Without the smaller
protuberances 22', the convection flow, because of its slow
speed, could flow around the large protuberances 22. The
smaller protuberances can be formed for example by roughing
the surfaces of the protuberances 22.
The reflective shield, screen or panel according to
the invention, particularly designed to be interposed between
a radiator 12 and a dividing wall 14 where the problem of
heat exchange is important, can of course be used for other
applications. Figure 3 illustrates, by way of example, the
disposition of a reflective shield, screen or panel 10
according to the invention in the air space 38 of a wall 14.
The shield, screen or panel 10 is in thermal contact with the
wall 14 only by its ends, and all conduction is practically
prevented because of this. The blocking of convective streams
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at the-front and rear of the shield, screen or panel is
effected in the way described above, as is the reflection
of rays.
Figure 5 shows a self-contained modular assembly
constituted by a sawtooth profile 40 fixed to a rear support
plate 42, so as to form a space 20, analogous to that shown
in Figure 1. The assembly can be of a hollow plastic material,
and behaves like a cellular thermal insulator. Its function-
ing is of course identical to that described above.
As shown in Figure 9, the asymmetric panel of the
invention may be disposed horizontally. The convection flow
with the panel so disposed can be easily compared to that of
a symmetric panel as shown in Figure 10.
The reflective shield, screen or panel according to
the invention advantageously replaces conventional thermal
screens, such as glass wool or porous materials, and has the
advantage of retaining its properties even in a damp environ-
ment, and of having a weight which is lower by a factor of as
much as 3 to 10. As pointed out above, several modules can,
of course, be associated to constitute multiple screens or
screens of greater surface area.
The reflective shield, screen or panel according to
the invention can be applied in horizontal position. The
relative convection flows for a sawtooth profile are shown in
Figure 9, where the convection blockade areas are powdered.
Figure 10 shows the convection flows modes for a symmetrical
profile, where no convection blockade occurs.
The invention is, of course, not limited to the
particular embodiment described and shown in the attached
drawing, but includes variations thereof which will occur
to persons skilled in the art.
