NO772707L - DEVICE FOR INSULATION AGAINST HEAT TRANSFER BY CONDUCTION, CONVECTION AND RADIATION - Google Patents

Description

"Device for insulation against heat transfer

by conduction, convection and radiation"

The present invention relates to another device

insulation against heat transfer by radiation, conduction and convection in areas where only relatively thin insulation can be installed. The device can take the form of a roller blind and can be used to insulate such surfaces, e.g. windows and doors in residential, office and industrial buildings, which are normally relatively good conductors of heat.

In recent years, it has become quite clear that the currently known sources of energy extracted from the earth are finite and are in fact rapidly being depleted. It has therefore become an important national concern to take care of energy.

The heating and cooling systems in residential, industrial and office buildings use approximately 25% of all energy consumed in the United States. It is therefore important to note that transparent, single panes or double insulating panes in these buildings are very poor heat insulators and consequently constitute a significant cause of inefficient energy consumption. Winter time is e.g. the heat loss per unit area through windows typically 3-10 times as large as through adjacent walls depending on the type of wall insulation. Correspondingly, the total heat that enters through a window in the sun in summer can be ten times greater than the heat that passes through the adjacent wall. (See ASHRAE, Handbook of Fundamentals (1972),

R. C. Dix and Z. Lanvan, "Window Shades and Energy Conservation", Mechanics, Mechanical and Aerospace Engineering Department, Illinois Institute of Technology, 1974). Considerable amounts of energy can therefore be saved if window surfaces are insulated effectively. However, it is desirable to do this without blocking the windows permanently and thus preventing their use for ventilation and as a view of the outside world.

It can also be advantageous to insulate other areas where the permitted thickness of the insulation is limited.

Many different attempts have been made to provide insulation against heat passing through building surfaces such as windows where only thin devices can be installed. E.g. shows an investigation conducted at the Illinois Institute of Technology by R.C. Dix and Z. Lavan, and which was published under the title "Window Shades and Energy Conservation", that a regular, single-track blind is better than both blinds and blinds when it comes to preventing unwanted heat loss through windows. The insulating effect is further improved if the roller blind is sealed around the edges with adhesive tape and provided with a white or silver reflective surface (see the above-mentioned publication at 23).

In US-PS 2 30,008J> there is described a heat-insulating window-curtain construction which is retractably mounted at the upper end of a window frame and includes two curtain paths separated by means of a spacer in the form of a wooden slat attached to the window frame. However, this device is subject to certain practical disadvantages. The spacer strip tends to wear on the webs when they are pulled past it, which causes wear on the curtain. Furthermore, there are no means to seal the curtains against the window frame or to otherwise prevent convection air currents from occurring in the space between the curtain tracks when these are drawn in front of the window. This is a main source of failure of the insulating effect which the device according to US-PS 2 305 085 entails.

In ASHRAE, Handbook of Fundamentals (1972) it is considered

total emissivity from two surfaces that have different average emissivities and enclose a single air space. However, no mechanical construction is described.

Other curtain constructions are described in US-PS 2,140,049,

2 328 257 and 2 865 446. Each of these constructions is designed to control the admission of light and air through a window in the same way as a normal roller blind and is not suitable for use as an insulation against heat loss. E.g. The curtain structures described in US-PS 2,140,049 and 2,328,257 have perforated webs which effect convection air currents around the curtain webs and the windows to which the webs are mounted. In a similar way, the curtain tracks according to US-PS 2,865,446 are made of a loose-meshed fabric which will not prevent such convection air currents from occurring.

US-PS 3 231 006 describes a pneumatically operated roll-up closure device including several layers which form inflatable pockets containing a fluid. However, according to this US patent document, the arrangement is not intended as an insulation, and nowhere in the patent document is there anything said about the desirability of giving the surfaces of the multi-layer construction low emissivity properties. In particular, the limits of emissivity which provide an acceptable construction according to the present invention are not mentioned anywhere.

Other devices used to cover windows are described in US-PJ, 2 247 634, 2 324 423 and 2 361 762. However, the devices described provide as poor thermal insulation as ordinary windows.

As described in detail below, the device according to the present invention is mounted to temporarily or permanently cover an area or a surface to be insulated against heat transfer. The area can be a wall or an opening, e.g. a window, in a building. When the device is made according to its preferred embodiment where it serves to insulate a window, it functions as a roller blind which can be either fully drawn or rolled up or set in any intermediate position and therefore need not impede the normal use of the window to allow air ventilation and the admission of light. However, when the roller blind device is drawn down at night during the winter months, a significant energy saving is achieved by preventing a significant loss through the windows of the heat provided by the heating system in the building. When the roller blind device is pulled down during the day in the summer months, significant energy savings can be achieved in a similar way by limiting the supply of heat and thus reducing the need for the cooling normally provided by the air-conditioning system in the building.

The curtain device according to the present invention is designed for use on ordinary windows, e.g. double sliding windows that are slidably mounted in a frame. The device includes a plurality of matte or translucent, i.e. mainly opaque, non-perforated roller blind webs attached to an on/off roller, i.e. a roller blind rod mounted to extend horizontally across the window frame at its upper end. The tracks can be pulled down from the roller blind rod to cover the window or fed back onto the rod to expose the window. Of course, the roller blind device can be mounted so that it can be pulled sideways over the window.

On one of the tracks in each pair of adjacent roller blind tracks, a series of spacers are arranged to separate the tracks when they are pulled down to cover the window, and to form dead air gaps between them. The spacers can be folded

only or nested within each other so that the track layers can be tightly packed when they are rolled up on the roller blind rod. Because the spacers are mounted on the individual roller blind tracks and travel with them during the lowering and raising operations, there is minimal rubbing that would tend to wear out the tracks or tear up the surface. Other non-abrasive embodiments of spacers that are not mounted on the roller blind tracks are also described.

At least one of the roller blind tracks has a low-existance surface facing a dead air gap. The excitation for the surface is sufficiently low to give a total effective emissivity of the surface, and the dead air space of no more than 0.60. The flat emissivity of the surface is in particular not greater than 0.60.

Thus, the spaces with dead air between adjacent roller blind tracks will form an effective thermal insulation against heat transfer by conduction and convection. Furthermore, the low-existance surfaces together with the plurality of dead air spaces provide a device that has a low total emissivity and very effectively inhibits heat transfer by radiation.

The roller blind device according to the present invention also provides certain practical advantages. In particular, it can be installed just as easily as a regular roller blind using similar fittings. Because the low-existance surfaces included in the present device are not worn or scratched by the spacers, which either move along with the tracks or are fixed, a long life of the roller blind device can be achieved to effectively insulate a window against heat transfer. Because the device is simple, it can be manufactured economically and therefore has a wide range of applications.

The device according to the invention can be used to insulate

other building surfaces, e.g. floor-to-ceiling windows, sliding doors with or without glass panes and standard doors. Furthermore, the device can be made in other ways than as a roller blind.

E.g. it can be mounted extended in a non-retractable manner to insulate a wall or other surface, and it can be mounted to

stretch horizontally, vertically or at an angle.

It is thus a purpose of the present invention

to provide an insulation that effectively and in a practical way insulates against heat transfer by conduction, convection and radiation through building areas or surfaces that allow the installation of in-

directions that have a relatively small thickness.

Other purposes and advantages of the present invention will be pointed out in or appear from the following detailed description in connection with the drawing. Fig. 1 is a perspective view of a roller blind device according to the present invention in the lowered position, seen from the inside of a normal window in which it is mounted. Fig. 2 is an elevation of the roller blind device, seen from the inside of the window in which it is mounted, and shows it in a partially retracted position. Fig. 3 is a vertical section through the roller blind device and the window in a plane 3-3 in fig. 1 and set to the left. Fig. 4 is on a larger scale a section of a section similar to that shown in fig. 3, and shows preferred means for holding adjacent roller blind tracks at a distance from each other to form a dead air gap between them. Fig. 5 is another cross-section on a larger scale of these spacers and shows the way in which they fold together or are inserted into each other when they are pulled back on the roller blind rod.

Fig. 6 is a vertical section through a device which constitutes

an alternative to that shown in Figure 3, which serves to seal the upper end of the roller blind device to prevent convection currents from occurring between the device and the window.

Fig. 7 is a vertical section in plane 7-7 in fig. 1, viewed in a downward direction, and shows a suitable device for sealing the sides of the roller blind device to prevent such convection currents from occurring. Figs. 8, 9 and 10 are sections of vertical sections similar to those shown in fig. 3, and illustrates alternative means for spacing nabb roller blind webs so as to form between them a series of dead air spaces. Fig. 11 is a vertical section similar to fig. 3 of another embodiment of the invention, and shows yet another embodiment of the spacers and a mounting of the device so that it extends at an angle.

Fig. 12 is a perspective view of the embodiment of fig<1>. 11

with some parts cut away to show detail.

Figs. 13, 14, 15 and 16 are vertical sections of alternative spacers which are particularly useful in the embodiment of the invention shown in fig. 11 and 12. Fig. 17 is a vertical section through an automatic and/or remotely controlled embodiment of the invention. Fig. 18 is a perspective view showing the location of a photoelectric cell to operate the automatic embodiment of the invention shown in Fig. 17. Fig. 19 is a vertical section through another automatic embodiment of the invention.

As shown in fig. 1 and 2, is the device according to the present invention, which is here designed as a roller blind and in general

designated by 10, mounted to be pulled down in front of a normal window

which is generally shown at 12, to insulate the window against heat transfer by conduction, convection and radiation. However, this roller blind device can be used with the same advantage to isolate any opening, e.g. a sliding glass door in an office, institutional, industrial or residential building against heat transfer. ^LjJcele des, it may take the form of a permanent non-retractable isolas ion_&_ lu^ for example a wall.. As an example, however, the window 12 may be a double vertical sliding window comprising a frame 14 extending around the sides and the top, and a window post 16 which projects horizontally from the underside. An upper and a lower slatted window panel, 18 and 20 respectively, are mounted in a well-known manner, each window panel being slidably mounted in vertically extending grooves (not shown) for upward and downward movement. Furthermore, the window

the panels some distance inside the frame 14.

As shown in fig. 3, the roller blind device 10 has a series of substantially opaque, non-perforated roller blind tracks 22

which is attached to a rotatable roller blind rod 24 which is mounted so that it extends horizontally over the entire frame 14 at its upper end. (Note that the thickness of the roller blind tracks 22 is exaggerated for the sake of clarity). Commonly available or slightly modified fittings can be used for storing roller blinds

the rod, which can advantageously include a conventional, spring-loaded winding mechanism (not shown) similar to that normally used for ordinary roller blinds. This roll-up mechanism provides a means of moving the roller blind webs between a retracted position (Figs. 1 and 3) and a firmly packed rolled-up or retracted position.

One path of each pair of neighboring roller blind paths 22 is carried out with

a plurality of members 26 to keep the neighboring webs at a distance from each other when they are in the lowered position as shown in fig. 3.

Moreover, these spacers or pieces can be fitted closer together at the upper end of each web to effectively separate the neighboring webs in the area where they tangentially leave the roller blind rod 24 and thus tend to lie together.

In the preferred embodiment shown in detail in FIG

fig. 4, each spacer 26 is formed by an elongated, flexible tape-like strip which will assume a partially cylindrical or curved shape with an axis parallel to the main axis of the tape-like strip and at its upper edge 27 is attached, e.g. by welding or sewing, to the web surface to extend horizontally or across the web. (Note that the thickness of spacer 26 also

is exaggerated for clarity.) However, the lower edge 29 of each spacer is free. Furthermore, each spacer 26 is made of a material which has a very good "elastic memory", i.e. that the material, when shaped into the desired arch shape, naturally returns to this shape after deformation. In addition, the pieces should be heat cured to prevent loss of the "elastic memory"

in the summer heat. Accordingly, the spacers 26 separate neighboring webs along the entire extended web length to form a dead air gap 38 between the webs. These dead air gaps act as insulation against heat transfer by conduction and convection.

As shown in fig. 5, as a result of their design, the spacers 26 are tightly packed on the roller blind rod 24 when the roller blind tracks 22 are rolled up on the rod. In particular, the radius of curvature of each spacer corresponds to the radius of the rod 24 when the piece is rolled onto the rod, and the lower strip edge 29

slides only slightly downwards on the neighboring track to the track it is attached to. The free end 29 is preferably rounded to ensure that the sliding movement, although small, is also smooth. However, because the spacer has a significant elastic memory, when the device is pulled off the roller blind rod 24, each spacer will tend to retain or remember the radius of the rod 24 to keep adjacent webs apart as opposed to when the webs are rolled up.

While again referring to fig. 3, it will be seen that the rear ends 31 of respective webs 22 are attached to the curved surface of the roller blind rod in a stepped pattern along the circumference. The spacers are also offset from one web to the other in slanted, vertical sets, so that only a small portion of one piece flaps against another on a neighboring web when the device is rolled up. Consequently, the distribution of the web and spacers will be relatively even when the device is rolled up on the curtain rod. Although the device may comprise many lanes, these will therefore be stored on the roller blind rod 24 in a relatively compact manner. in order to

take up insignificantly more space than a normal roller blind. E.g. it has been found that a device with three lanes which is approx. 2.4 m long and has a thickness of approx. 38 mm when extended, has a roll-up diameter of approx. 51 mm on a roller blind rod with a diameter of approx. 25 mm.

As shown in fig. 3, the outermost webs 22a and 22f are connected at 36 as a result of the fact that they are made of the same web material. Furthermore, each of the inner individual webs 22b - 22e is provided with an elongated plumb line 37 at the leading edge to provide the full extent of the web to a location where it touches or almost touches the continuous web 22a, 22f at location 36. The respective dead air spaces 38 is thus closed below by the outer webs 22a and 22f and their contact with the inner webs 22b - 22e, to prevent convection air currents from occurring between the webs. This is particularly desirable because such convection currents would interfere with the effective action of the dead air spaces in preventing heat transfer by conduction and convection.

When the tracks are rolled onto the roller blind rod, the radius for the tracks furthest from the rod axis is greater than for the tracks closest to the rod axis. The web 22f will therefore be rolled onto the roller blind rod 24 more quickly

than lane 22a. However, the continuous roller blind track construction permits easy roll-up without jamming despite this condition because the tracks 22a - 22f pivot at location 36. Also, the weighted or weighted ends of the inner tracks 22b - 22e will be rolled up in an offset manner due to the difference in the radial distance to the respective lanes on the curtain rod. Suitable washers or large washers can be installed on

the ends of the roller blind rod 24 to ensure that the webs are rolled evenly onto the rod.

According to the present invention is at least

one of the roller blind paths provided with a surface 39 which has low excitation or emissivity, and which faces the dead air gap 38. Emissivity is defined as the ratio of the total radiation flux from a surface to the radiation flux from an ideal black body at the same temperature. In the preferred embodiment, at least one and preferably both sides of each of the inner tracks 22b - 22e has a low-existance surface and can e.g.

be produced from copper, nickel, aluminium, silver or gold foils or foils from alloys of these metals. A material sold under the trademark "Mylar" by E.I. DuPont de Nemours & Co., is also suitable for use as roller blind tracks to provide a low-existance surface, if the material is provided with an aluminized coating.

It has been found that each low-excitation surface should have a surface excitation sufficiently low to give a total effective emissivity of the surface and its associated dead-air gap of at most 0.60. Effective emissivity is defined as the combined effect of the interface emissivity and dead air space. The maximum acceptable surface emissivity of a single surface 39 facing a single dead air gap 38 is therefore 0.60.

In the preferred embodiment of the invention, each low-excitation surface will have a surface emissivity that is sufficiently low to give a total effective emissivity of the surface and the associated dead air space that is not greater than 0.06. Thus, the maximum preferred surface emissivity of a single surface 39 facing a single dead air gap 38 is 0.06. The acceptable surface emissivity can be achieved with any of the materials mentioned above.

Furthermore, the acceptable and preferred excitations and the total effective emissivities described above should be obtained in the infrared region of the energy spectrum and in the temperature range from -1.1°C to +54.4°C.

In light of the description above, the expression "low excitance" will be understood to mean that the emissivity is not greater than 0.60.

The low-existance surfaces combine synergistically with an associated dead air gap to effectively insulate against radiant heat transfer. If, in order to elucidate this more closely, thermal conductance U is defined as heat flow per time unit per unit temperature difference through a body (often per unit area) from one interface to another under stable conditions and thermal resistance R as the reciprocal value of thermal conductance, will R

be a measure of the body's ability to prevent heat transfer. The thermal resistance Rf of each surface or the film resistance of the free-standing roller blind tracks regardless of surface excitation is 0.68. As the resistance is additive, the total thermal resistance for the entire roller blind path is R^= 2R^= 1.36. The thermal resistance of two roller blind tracks with high surface excitation, which are separated from

fairy

each other to form a dead air gap, is R2 and is equal to the outer film resistance of both webs, 2R^= 1.36, plus the thermal resistance of the air gap Ras-^= 0.96. Consequently, R2= 2Rf + Ras^= 2.32. This would of course also be the expected resistance of the roller blind construction if the tracks had a low-existance surface. However, when the webs are provided with low-existance surfaces (as defined above) facing the air gap, the thermal resistance of the air gap is increased to RaS2<=><2>.95,

so that the total resistance R3= 2Rf + Ras2= 4/31. Similar results are obtained if more air gaps are added. The device according to the present invention, which comprises a plurality of roller blind tracks that enclose a plurality of dead air spaces each associated with a low-existance track surface, thus effectively insulates against heat transfer by conduction, convection and radiation.

According to the present invention, it is particularly important that the spacers do not destroy the low-existance surfaces when there is a retracting or winding mechanism. A stationary non-rotating spacer over which the roller blind tracks are drawn would scratch up these surfaces which are attached to or form part of the track face, destroying their low-existance property and thus limiting their effectiveness, along with the dead air gaps, in insulating against heat transfer. However, the spacers of the type described above keep surface rubbing to a minimum and thus protect the device and extend its life.

The roller blind device according to the present invention also includes certain features which prevent convection currents from occurring between the device and the window itself. As shown in fig. 3,

a flap 40 is attached to the outermost roller blind track 22a, which is weighed down by an elongated rod 42 in order to come to a firm position against the upper side of the window post 16 when the roller blind device is pulled down. Consequently, convection air currents will be prevented from occurring between the lower edge of the roller blind device and the window jamb. In a similar way, a cover in the form of two hanging loops or bends 44 is mounted on the underside of the horizontal, upper part of the frame 14. The loops 44 form a seal at the places 46 to also

form dead air gaps 47. Furthermore, each loop can have an internal low-existance surface 49. Because the loops are arranged to come into contact with the outermost roller blind track 22f when this is rolled in

on the roller blind rod 24, they effectively prevent convection currents from occurring between the frame and the upper side of the device and also prevent heat transfer by conduction and radiation.

As shown in fig. 1 and 7, a sealing device similar to the cover in fig. can be arranged on each side of the roller blind device. 3. This device 48, which is attached to the side parts of the frame 14, includes a pair of opposite bends 50 which form a seal at the places 51 and is formed e.g. of a plastic material with good elastic memory, and which is shaped to be in intimate contact with the edges of the roller blind device and prevent convection currents from occurring in this area. These meanders 50 also enclose dead air gaps 53 and may have an internal low-existance surface 55.

As shown in fig. 6, an alternative loop or meander device 57 can be used instead of one or more of the top or side closing devices in fig. 3 and 7. This device includes two bends 54 formed of compliant material which are shaped to press around the roller blind device as it is rolled onto the roller blind rod 24 regardless of the diameter of the device during different stages of the roller blind track winding.

Alternative embodiments of spacers are shown in fig. 8 - 10 and can be used to keep the roller blind paths separated in the manner described above. Each of the alternative embodiments of the spacers is shown to be arranged so that they are rolled up on a roller blind rod in a clockwise direction instead of in a counter-clockwise direction as shown in fig. 3. Fig. 8 shows spacers which are formed in one with the associated roller blind track and extend across it. In particular, each web 2 2 is provided with one first fold 58 in several places arranged at a vertical distance from each other which exceeds the elastic limit of the material from which the roller blind web is made, and is therefore permanent. The fold can e.g. folded in a counter-clockwise direction. The web is then folded back on itself in a clockwise direction at 60 forming a bend 62. The surface of the web 22 adjacent to the first permanent fold 58 is bonded to the contact surface at location 64, e.g. by means of glue or welding. The web is then folded into another permanent fold 66 again in a counter-clockwise direction at a location outside the adhesive location 64. Thus, a portion of the web will extend past the adhesive area to form a moment arm 68. When a tensile force, e.g. the weight of the web itself, as shown by arrow F, is exerted at the opposite ends of a roller blind web 22, the bends 62 attempt to pivot outward away from the plane of the web about the fold 58 as shown by arrow R. In this way, the bends 62 act as a transverse spacer between neighboring webs to form a dead-air gap 38 between them. The respective dead-air gaps serve as heat insulators in the same way as described above. The bend 62 is also shaped so that it is rolled tightly onto a winding device, e.g. the roller blind rod 24. Another alternative spacer is shown in fig. 9 and comprises a loop 70 which is formed by an elongated strip attached to the roller blind track 22 at its upper edge 72. The lower strip end is bent backwards and is finally attached to itself at 75. The loop material has poor elastic memory. When the roller blind device is pulled down, the internal radial forces in the loop will therefore cause it to assume an approximately circular-cylindrical shape and bring neighboring lanes at a distance from each other. When the loop 70 is rolled up on the roller blind rod 24, however, they will snap together and allow the roller blind tracks to be laid closely together in relation to each other."

A third alternative spacer design is shown in fig. 10 and comprises a tear-shaped loop 80 formed by an elongated strip which is connected by its common free edges to the roller blind track 22 at 82. Also the material from which the loop 80 is made has a poor elastic memory and assumes a pear-like shape when the device is pulled down , in an attempt to balance the internal radial forces.

Figs. 11 and 12 illustrate another embodiment of the present invention, which can be used to isolate any area that is isolated by the embodiment shown in fig. 3. However, this second embodiment is particularly useful when insulating areas or surfaces such as skylights, the roof of a greenhouse or any other surface that extends obliquely or horizontally. As shown in fig. 11, the roller blind device comprises a plurality of roller blind tracks 102 which are attached to a roller roll-up mechanism 104 in a manner similar to that described with reference to FIG. 3. The retracting or winding mechanism is mounted between two end brackets 106, only one of which is shown in fig. 11, and which is attached to opposite sides of the surface, e.g. on either side of a window frame or the side frame of a door. Between the brackets 106 there also extends a plurality of freely rotatable, upper distance rollers 108, each of which is mounted so that it is only in contact with one track of each pair of mutually bordering tracks. Each of the spacer rollers is provided with a non-abrasive surface, e.g. soft rubber, to prevent damage to the low-existance surfaces of the tracks detailed above.

This embodiment can also be provided with an upper cover 110, e.g. similar to that described with reference to fig.

3, to prevent convection air currents from passing over the device. This upper cover as well as the side seals which are described in connection with the embodiment in fig. 3, may be formed of a magnetic material to adhere closely to the device.

At its free ends, the roller blind device comprises a Y-shaped bracket 112 with end plates 114, only one of which is shown in fig. 11. Between the end plates 114 in the bracket 112, a number of freely rotatable lower distance rollers 116 are mounted, corresponding in number to the upper distance rollers 108. Here, too, the lower rollers are mounted at a distance from each other and can be provided with non-abrasive surfaces to prevent jamming of neighboring lanes when rolling up.

The outermost roller blind paths 102a and 102d are in reality

a single continuous web which is passed around the two outermost lower spacer rollers 106a and 106c. Similarly, the innermost roller blind paths 102b and 102c comprise a single continuous path which is guided around the middle, lowermost spacer roller 116b.

The hanging middle piece 118 of the Y-shaped bracket 112

is attached to a tension line or cable 120 which is passed through a suitable slot 122 in the window post 124 for the window surface to be insulated. The cable 120 is wound around a drum 12.6 which can be driven by a motor 128 via a worm drive device 130 or by means of a hand crank or traction device, not shown.

It can then be understood that the roller blind device can be pulled down to a preferred position as shown in fig. 11 from its retracted position which is close to that shown in FIG. 12, by means of the motor 128 which drives the drive device 130, the drum 126 and the cable 120. Furthermore, it will be understood that the arrangement of stationary spacers according to the second embodiment is particularly useful in applications where the roller blind device is mounted obliquely, e.g. as shown. This arrangement of stationary spacers keeps each of the webs 102 of the multilayer assembly spaced apart through the tension provided by the cable drive. It is also desirable to provide the retraction roller 104 with a strong spring or other driving means to ensure that between the top and the bottom of

the device has sufficient voltage.

As shown in fig. 11, resilient or magnetic seals 134 can be arranged on the upper side of the window post 124 to rest against the horizontal arms 136 of the Y-shaped bracket 112 when the device is pulled forward. These seals also prevent convection air currents from occurring under the device in the lowered position.

Fig. 13 - 16 show four alternative distance devices which have special use in connection with the embodiment of the invention shown in fig. 11 and 12, when neighboring roller blind tracks extend diagonally or horizontally.

The first form of spacers, which is shown in fig. 13, is similar to that described in connection with fig. 3. However, the shown spacers 140 are formed from an elongated strip of rigid material having a partially cylindrical or curved shape with an axis parallel to the main axis of the strip and are attached to the web surface e.g. by heat welding, sewing or gluing over the entire surface or at its upper edge 142 to extend horizontally or across the track surface.y Instead of there being a plurality of spacers extending through the roller blind device, only a single spacer is attached to a track in each pair of roller blind tracks in the area where the tracks are attached to the roller blind rod. Because the spacers 140 are rigid, the webs, when the device is moved to its retracted position, will be effectively separated as shown in FIG. 13.

Fig. 14 shows an alternative spacer which works by means of a similar principle to the embodiment in fig. 8.

This spacer comprises a rigid strip which has a partially cylindrical or curved cross-section with an axis parallel to the main axis of the strip. On one edge 146 of the strip on one side thereof, the spacer is attached to the middle roller blind track 102b. On the opposite side and the opposite edge 148, the spacer is also attached to the middle roller blind track 102b.

When this roller blind track is subjected to tension, the spacer 144 as shown in fig. 14 consequently tend to turn to a position that is not parallel to the roller blind path. In other words, the spacer seeks to turn outwards away from the plane through the middle lane as shown by arrow S. In this way, the spacer acts as a transverse separator between neighboring lanes to form a dead air gap between them. When the device is rolled up, the spacer can be folded against the roller blind tracks to pack tightly against the roller blind rod 104.

Fig. 15 shows a stationary spacer comprising a drum 150 which is concentric with respect to and encloses the roller blind roller 104. The drum is provided with a plurality of tracks 152 which extend in the direction of the axis A. Each roller blind track 102

is threaded through one of the grooves 152. The drum 150 is mounted together with the roller blind rod 104 so that the grooves 152 lie at a distance from each other across the planes in which the roller blind tracks extend, when the tracks are in the fully retracted position as shown in fig. 15.

Fig. 16 illustrates perhaps one of the least expensive spacer embodiments in the form of a rigid, elongate foam plastic comb member 154 which is attached to one of the two roller blind tracks 102

in the area where both webs are attached to the roller blind rod 104. The comb part extends across the webs. This spacer construction has particular application in situations where only two roller blind tracks are used, and where price is an important factor.

Fig. 17 - 19 show automatic and remote-controlled embodiments of the device according to the present invention. In fig. 17

the blind can be moved to its retracted and retracted positions by means of a motor 106 which drives a worm gear 162 and a worm wheel 164 which turns the blind rod 104 on which the multi-layer blind device is mounted. The motor 160 can be operated automatically by means of a photoelectric cell as described in more detail below, or can be selectively operated by a manual switch.

Furthermore, the motor shaft 166 can be turned via a pulley 168 around which a V-belt 170 is wound. This alternative device allows manual operation of the roller blind device.

It may be desirable to enclose the device between two panes of transparent material 220, e.g. glass. The squares serve to reduce the convection currents that can occur between the parallel paths in the device to a minimum. In the space formed between the panes, a slight negative pressure can be maintained to further suppress convection loss.

Fig. 18 and 19 show an independent motor drive device for the device according to the invention. This embodiment includes a power system that is mounted inside the roller blind rod 104, and which includes a flat blade 180 that can engage with a conventional mounting bracket 182 attached to the window frame 184. The blade 180 includes separate portions 186 resp. 188 which are separated by means of a solid insulating shaft 190. Each of the separated parts of the blade 180 is in contact with suitable spring contacts 192 and 194 mounted on the inside of brackets 182. Furthermore, the electrically separated parts are connected through the shaft 190 with a commutator 196 which is arranged to form electrical connection with two brushes 198 and 200. The brushes are in turn connected to a motor 202 and a microcomputer 204. The motor has a shaft 206 provided with a pivot 208 which drives a translation 210 as in

in turn drives a gear ratio mounted in a gearbox 215.

A gear 212 meshes with a gear 214 which is non-rotatably secured to the stationary shaft 190. Accordingly, when the motor is actuated, the roller blind will rotate by interaction with the stationary shaft 190. To make the free rotation of the roller blind device easier, there arranged .a-Etti-f-r-i-k-s-j-ønstores 216.

The outer contacts 192 and 194 are connected to a photoelectric cell 218 which is mounted on the window 220 where the device according to the invention is installed, as shown in fig. 18. The photo-electric cell is affected by incident light from the external environment. The microcomputer 204 is optionally programmed to move the device to the lowered position during the time when there is daylight during the air conditioning season. During the air conditioning season, the device is similarly moved to its coiled position at night. During the heating season, the opposite is the case. In particular, the microcomputer is programmed to activate the motor to move the device to the retracted position at night during the heating season and to the rolled-up position during the day during the heating season.

As will be understood from the preceding description, many embodiments of the invention are conceivable. It can be adapted to different environments to meet special insulation requirements.

It has been found that the use of the device according to the present invention throughout the year can result in significant energy savings. When the device is used in winter, it prevents a significant heat loss from the inside to the outside of an opening in a building where the device is installed. The device can be used most effectively at night in the winter months. In the summer months, the device according to the present invention can similarly prevent large amounts of unwanted heat from entering the building from the outside through openings in the building. As an example, it has been found that the preferred embodiment of the present invention, which has six roller blind tracks and contains five dead air spaces, produces the following results:

These results were obtained when both sides of each of the interior roller blind tracks were provided with a low-existance surface facing a dead-air gap and the emissivity E for each dead-air gap was equal to 0.03. It is clear that, relative to an uncovered window, the present device represents a sixteen-fold improvement in preventing heat transfer, if all other variables are held constant.

It should be noted that the present invention can be implemented with more or less than six roller blind tracks. However, it has been found that the minimum number of lanes that provide acceptable results is three, thus including two dead air gaps. Such a roller blind device produces the following results:

This arrangement provides an improvement over a single figure-of-eight window in terms of preventing heat transfer by convection, conduction and radiation, provided all other variables are held constant.

In the preferred embodiment, the device according to the present invention is therefore very effective when it comes to

prevent heat loss and thereby provide a significant energy saving.

Although particular embodiments of the present invention are. been described above in detail, it is to be understood that this is for descriptive purposes only. The described constructions can be modified to adapt the invention to special insulation applications. f

Claims (29)

1. Device for insulating a surface such as a window, a door or a wall against heat transfer by conduction, convection and radiation, characterized in that it consists of: A. a plurality of substantially opaque, non-perforated curtain webs; B. means for separating each pair of neighboring webs to form a dead air gap between them, and C. a low-emittance surface that is associated with at least one of the curtain tracks and faces the dead air gap, and which has a surface excitation which is sufficiently low to give a total effective emissivity of the surface and the dead-air space of no more than 0.60. 2. Device as stated in claim 1, characterized in that the total effective emissivity of the surface and the dead air space is not greater than 0.06. 3. Device as specified in claim 1, characterized in that the surface emissivity of the surface is not greater than 0.60. 4. Device as specified in claim 1, characterized in that the surface emissivity of the surface is not greater than 0.06. 5. Device as stated in claim 1, characterized in that the total effective emissivity of the surface and dead air space of no more than 0.60 is achieved in the infrared range of the radiation energy spectrum. 6. Device as specified in claim 1, characterized in that the total effective emissivity of the surface and dead air space of no more than 0.60 is achieved in the temperature range from - 1.1 to + 54.4 °C. 7. Device as specified in claim 1, characterized in that the total effective emissivity of the surface and dead air space of no more than 0.6 0 is achieved in the infrared range of the energy spectrum and in the temperature range from - 1.1 to + 54, 4 °C. 8. Device as stated in claim 1, characterized in that the two outermost curtain tracks are connected at at least one end to seal the dead air space between neighboring tracks and thus prevent convection air currents from developing in the spaces. 9. Device as specified in claim 8, characterized in that the two outermost curtain webs of a plurality of webs are produced continuously from the same material web. 10. Device as stated in claim 1, characterized by sealing means to prevent convection air currents from developing between the device and a surface it covers. 11. Device as stated in claim 10, characterized in that it comprises retraction means for mounting the curtain tracks for movement by choice between a preferred position where they cover the surface, and a retracted position where they do not cover the surface. * 12. Device as stated in claim 11, where the device is mounted at an upper part of the surface to be pulled down over it from the retraction device, and where the surface has a lower frame surface, characterized in that the sealing device comprises a flexible flap mounted on the outermost track opposite the surface to rest on the frame surface and prevent air currents from passing under the device. 13. Device as specified in claim 11, characterized in that the sealing member comprises a flexible sealing device which is mounted on the surface that the curtain is to cover, and which engages with the sides of the curtain tracks when these are in a preferred position to prevent convection air currents from flow past. 14. Device as stated in claim 11, where the device is mounted on an upper part of the surface to be pulled down over it from the retraction device, characterized in that the retraction device comprises a flexible sheath mounted at the top of the surface to come into contact with the curtain tracks which are mounted on the retraction means, both when these are in the extended and retracted positions and to prevent convection air currents from flowing past the upper side of the device. 15. Device as specified in claim 1, characterized in that it further comprises retraction means for storing the curtain tracks for movement by choice between a preferred position where they cover the surface, and a retracted position where they do not cover the surface. 16. Device as stated in claim 15, characterized in that it further comprises a pair of mutually parallel transparent panes which are mounted in the area to be covered by the device, the device being mounted for movement to its preferred position between the panes. 17. Device as stated in claim 15, characterized in that the curtain tracks extend at an angle with the vertical when they are in a preferred position. 18. Device as stated in claim 17, characterized in that the retraction means are arranged to influence the roller blind tracks towards their retracted position, and that the device further comprises tensioning members which serve to influence the curtain tracks towards their preferred position in order to keep them at an angle with the vertical. 19. Device for insulating a surface such as a window, a door or a wall against heat transfer by conduction, convection and radiation, characterized in that it is comprised of: A. a plurality of substantially opaque, non-perforated curtain webs; B. retracting means for mounting the webs for movement as selected between a preferred position where they cover the surface, and a retracted position where they do not cover the surface, and C. spacers mounted to separate adjacent webs to form a dead-air gap therebetween, the spacers including a roller for each pair of webs, and the rollers being mounted for free, non-abrasive rotation of the webs in stationary relation to the retraction means to touch only one of each pair of tracks when these are in the preferred position. 20. Device as stated in claim 19, characterized in that the rollers are provided with a non-abrasive surface. 21. Device for insulating a surface such as a window, a door or a wall against heat transfer by conduction, convection and radiation, characterized in that it consists of: A. a plurality of substantially opaque, non-perforated curtain webs; B. retracting means for storing the curtain tracks for movement according to choice between a preferred position where they cover the surface, and a retracted position where they do not cover the surface and, C. spacers mounted to separate adjacent webs and to form a dead air gap between them, the spacers comprising at least one spacer comprising an elongated strip formed of rigid sheet material having a curved cross-sectional shape with an axis extending in the direction of the major axis of the strip, at the same time as one of the edges of the strip extending in the direction of the axis, is attached to one of the curtain tracks. 22. Device as stated in claim 21, characterized in that the retraction means is a rotatable rod, and that the elongated strip is attached to the web to curve in the same direction as the rod when the webs are rolled onto it. 23. Device for insulating a surface such as a window, a door or a wall against heat transfer by conduction, convection and radiation, characterized in that it consists of: A. a plurality of substantially opaque, non-perforated curtain webs; B. retracting means for storing the curtain tracks for movement as chosen between a preferred position where they cover the surface, and a retracted position where they do not cover the surface, and C. spacers mounted to separate neighboring webs to provide a dead air gap between them, the spacers comprising at least one spacer comprising an elongated strip formed of rigid sheet material having a curved cross-sectional shape with an axis extending in the direction of the main axis of the strip, one of the edges of the strip extending in the direction of the axis being attached to one side of the web and the other edge of the strip being attached to the opposite surface of the same web, so that the web under the influence of tension gets the strip to turn towards a position perpendicular to the surface of the track. 24. Device for insulating a surface such as a window, a door or a wall against heat transfer by conduction, convection and radiation, characterized in that it consists of: A. a plurality of substantially opaque, non-perforated curtain webs; B. retracting means for storing the curtain track for movement as chosen between a preferred position where it covers the surface, and a retracted position where it does not cover the surface, and C. spacers to separate neighboring tracks in order to form a dead air space between them, the spacers comprising a member which is connected to the retracting member and is made with a plurality of spaced apart parallel tracks and the curtain tracks are led through each track, at the same time as the means is adapted to keep the tracks at a distance from each other in a direction which is not parallel to the curtain paths, when the device is in the preferred position. 25. Device for insulating a surface, such as a window, a door or a wall against heat transfer by conduction, convection and radiation, characterized in that it consists of: A. a plurality of substantially opaque, non-perforated curtain webs; B. retracting means for storing the curtain tracks for movement as chosen between a preferred position where they cover the surface, and a retracted position where they do not cover the surface, and C. spacers mounted to separate neighboring webs to provide a dead air gap between them, the spacers comprising a cam member mounted on one of each pair of webs in the attachment area for the webs of the mounting bodies. 26. Device for insulating a surface, such as a window, a door or a wall against heat transfer by conduction, convection and radiation, characterized in that it consists of: A. a plurality of substantially opaque, non-perforated curtain webs; B. retracting means for storing the curtain tracks for movement as chosen between a preferred position where they cover the surface, and a retracted position where they do not cover the surface, C. spacers fitted to separate neighboring lanes to form a dead air gap between them, and D. means for influencing the retraction means in response to ambient conditions on the outside of the surface. 27. Device as stated in claim 26, characterized in that the winding means comprise A. motor means for driving the retraction means for movement of the curtain webs between the retracted and retracted positions, and B. sensor organs for sensing ambient conditions. 28. Device as stated in claim 27, characterized in that the sensor means comprise a light sensor. 29. Device as stated in claim 28, characterized in that: it further comprises a microcomputer connected to the light sensor and the motor means, the computer being programmed to activate the motor means to move the curtain tracks to a preferred position when there is daylight, and to a retracted position at night during the air conditioning season, and to move the tracks to a preferred position at night and a retracted position during the day during the heating season.