A FOAM PADDING HAVING HOLLOW VOLUMES AND A FLEXIBLE BAND
20210244192 · 2021-08-12
Inventors
Cpc classification
A47C7/746
HUMAN NECESSITIES
B68G11/04
PERFORMING OPERATIONS; TRANSPORTING
International classification
Abstract
A foam padding (10) is disclosed. The foam padding (10) has sections (32, 34), each covering at least one hollow volume (12, 14) of the padding said padding (10) including a flexible elongated band (20) for transferring thermal energy from at least one hollow volume (12) in a first one of said sections (32) in the event of excess thermal energy towards at least one hollow volume (14) in a second section (34) in the padding (10) not containing excess thermal energy. The band (20) has a continuous electrically conducting layer (22) with a defined area extending from at least one first section (32) to another different second section (34).
Claims
1. A foam padding having sections, each covering at least one hollow volume of the padding, said padding including a flexible elongated band for transferring thermal energy from at least one hollow volume in a first one of said sections in the event of excess thermal energy towards at least one hollow volume in a second section in the padding not containing excess thermal energy, said band having a continuous electrically conducting layer with a defined area extending from at least one the first section to another different second section.
2. The foam padding according to claim 1, wherein said band is positioned such that at least 30% of the defined area is positioned outside of the first section.
3. The foam padding according to claim 1, wherein the first section is a section prone to be warmer than said second section and/or prone to be used for supporting a human body or a part of a human body, whereas the second section isn't.
4. The foam padding according to claim 1, wherein said band has dimensions of at least 4 cm in width and/or at least 25 cm in length.
5. The foam padding according to claim 1, wherein said sections are dimensioned to cover at least a surface of the padding corresponding to 0.08 m.sup.2 or 10% of the overall surface.
6. The foam padding according to claim 1, wherein said band is punctured and/or perforated.
7. The foam padding according to claim 1, wherein said band is laminated on one or both sides with PE, PU or other stabilizing materials.
8. The foam padding according to claim 1, comprising at least one section with gel-infused foam wherein said band extends through said at least one section with gel-infused foam.
9. The foam padding according to claim 1, comprising at least one insulating layer.
10. The foam padding according to claim 1, wherein the band is arranged such that at least 20% of the defined area is exposed or outside of the padding.
11. The foam padding according to claim 1, wherein the band is 0.1 mm to 0.5 mm thick and/or has a width of 4-10 cm.
12. The foam padding according to claim 1, wherein the electrically conducting layer is made from graphite.
13. The foam padding according to claim 1, wherein the band is having density greater 1 g/cm.sup.3.
14. The foam padding according to claim 1, wherein the electrically conducting layer has a content of Sulphur lower than 1800 ppm.
15. The foam padding according to claim 1, wherein the electrically conducting layer is made of graphene.
16. The foam padding according to claim 1, wherein the padding is a mattress.
17. The foam padding according to claim 9, wherein said insulating layer is positioned at the second section such that the second section is shielded from external heat.
18. The foam padding according to claim 12, wherein the graphite has a carbon-content greater than 99%, and the band has a content of ash lower than 1% or is highly oriented pyrolytic graphite (HOCG).
19. The foam padding according to claim 2, wherein the first section is a section prone to be warmer than said second section and/or prone to be used for supporting a human body or a part of a human body, whereas the second section isn't, wherein said band has dimensions of at least 4 cm in width and/or at least 25 cm in length, wherein said sections are dimensioned to cover at least a surface of the padding corresponding to 0.08 m.sup.2 or 10% of the overall surface, and wherein said band is punctured and/or perforated.
20. The foam padding according to claim 19, wherein said band is laminated on one or both sides with PE, PU or other stabilizing materials, wherein the foam padding further comprises at least one section with gel-infused foam wherein said band extends through said at least one section with gel-infused foam, wherein the foam padding further comprises at least one insulating layer, and wherein the band is arranged such that at least 20% of the defined area is exposed or outside of the padding.
Description
SHORT DESCRIPTION OF THE FIGURES
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DETAILED DESCRIPTION OF THE INVENTION
[0027] In the following aspects of the invention will be described in more detail referring to preferred embodiments as illustrated in the figures. The following description is for illustrative purposes, only and is not intended to restrict the scope of protection as defined by the appended claims. Features shown in one embodiment may be combined with features of other embodiments and the person skilled in the art will appreciate, that the illustrated embodiments are merely provided for a better understanding of the inventive concept.
[0028] In the following a mattress as an embodiment of the padding according to the present invention will be described in more detail. The thermal comfort of a mattress is critical to obtaining a comfortable experience. There is a growing trend in the mattress industry to employ new materials which create a cooling effect for users with the use of innovative phase change materials (PCMs) or cooling gels included in the near-surface foam of a product. These materials seek to alleviate overheating during use or provide a more comfortable environment for those who may suffer from medical conditions which cause excess heat production.
[0029] The comfortable temperature window during sleep is relatively narrow as the body must try to maintain its core body temperature of 98.6° F. (or 37° C.). Haex reports that the optimal insulating sleep system should ensure a bed temperature between 28 V and 32° C. which should allow the contact temperature between the body and bed to stabilize between 30° C. and 35° C. Too high of a bed insulation will result in temperature rise which leads to excessive sweating and an increase in relative humidity. On the other hand, if insulation is too low, the body will cool off which may cause shivering and similar issues with sleep disturbance. These insulating properties are mainly dependent on the core materials and design. Cores made out of latex or PU for instance, will carry higher insulation values than a spring mattress. Aside from the core, the contact temperature itself is mainly dependent on the top layer and its ability to hold air.
[0030] There are not many solutions to this challenge for designing a mattress. Since ‘feeling hot’ is a feel of temperature, designers are looking for methods to reduce temperature. They are looking for ‘cooling’—may it be active or passive. This leads to solutions with an air conditioner combined with a mattress, with ventilators, materials with high thermal connectivity blended into foam or with channels cut into foam materials running along the mattress. These methods are either expensive (air conditioner), noisy (ventilator) or not working at all (blending thermal conductive materials into foam, channels).
[0031] The main problem is that product designers see temperature as the parameter to be changed, so they end up with ‘cooling’ materials or methods. But temperature is only the result of the change of other parameters and not an elemental parameter by its own. The temperature of any material is the result of
T.sub.(Mat@t)=T.sub.(Mat@t-1)+E.sub.(therm-inflow)−E.sub.(therm-outflow)
[0032] With T.sub.(Mat@t) being the Temperature of a given material at a given time, T.sub.(Mat@t-1) being the Temperature of this material before this given time, E.sub.(therm-inflow) being the thermal energy reaching the material between t−1 and t and E.sub.(therm-outflow) being the thermal energy leaving the material between t−1 and t. Based on this assumption a change of the temperature is not done by changing the temperature of the material itself but rather analyzing and optimizing the thermal energy flows effecting the materials.
[0033] In analyzing the thermal energy flows within a mattress, most product designers assume that thermal energy moves upward, like warm air, which rises if within cooler air. But as this invention teaches this assumption is not helping to design a mattress having superior thermal properties. It is true that warmer air rises within cooler air, but this only effect air. It is not directly the thermal energy itself which rises, but the physical effect that air with a higher level of thermal energy is lighter than air with a lower level of thermal energy. As air molecules can slide past each other easily, as the density of air is gaseous, the lighter air will have the tendency and capability to rise above the heavier air. But thermal energy itself has no weight and there is no gravity involved in moving thermal energy. Also helping warmer air to move upwards would only get the elevated thermal energy closer to the user instead of further away, as the user will in most cases lie on top of the mattress. But any method to reduce temperature should move thermal energy away from the user—not towards him.
[0034] Taking above mentioned formula, in order to lower the temperature in a material you either have to lower the inflow of thermal energy or raise the outflow. In a typical mattress, most inflow of thermal energy is from the impact of body heat. The body during sleep emits a heat flux of 40 W/qm skin, approx. 70-80 W/person which translates to an influx of 230 kJ per night. Additional influx of thermal energy can be heating devices used, or thermal energy used in conjunction with dynamic foams. There is no realistic method to reduce the inflow of thermal energy into a mattress, and the quantity of this inflow is obviously high.
[0035] The invention raises the outflow of thermal energy within a mattress. It uses materials itself flexible, so they can be incorporated in a mattress without reducing the comfort feeling. The invention is not using energy and is not transporting the excessive thermal energy upwards as warmer air would do. Therefore, the invention can be used to transport excessive thermal energy to the side or bottom of a mattress or to any section not felt by the user.
[0036] The invention utilizes a property of modern—mostly foam based—mattresses that thermal energy is not distributed evenly within the product. Old innerspring mattresses had a very open air-filled space within and around the springs. Thermal energy could move freely within the mattress therefore distributing excessive thermal energy from the body heat to sections of the body with less impact of body heat and therefore, the excessive thermal energy could not be felt by the user. But modern foam-based mattresses are very different in this respect. Polyurethane foam typically has many hollow volumes (usually called cells), which are either open (connected to each other) or closed (not connected to each other). These hollow volumes contain air, which gradually is becoming warmer with use. Even with open cell foams the movement of this air is very restricted and also air would move upwards towards the user, but not away from him. Besides the air as a transport medium for thermal energy within the mattress the foam material itself could be a transport medium for thermal energy. But foam has a low thermal conductivity. Foam material cannot transport thermal energy very well or rather not at all. There are solutions to blend material with a higher thermal conductivity with foam, so that the material can transport thermal energy away from the body. But these blended materials cannot transport thermal energy as the molecule chains with higher thermal conductivity are usually interrupted by molecule chains of Polyurethane stopping thermal energy flow. So, the molecule chains blended into foam can absorb some but not transport the excessive thermal energy. As mattresses are used for long periods up to 10 hours thermal energy must be transported away and not only absorbed.
[0037] This is also the reason why PCM's (Phase Change Material) are not effective in mattresses. The PCM will absorb some thermal energy (i.e. 9 KJ/m.sup.2) but by far not the 230 kJ emitted during a typical night.
[0038] Therefore, this invention is not absorbing thermal energy from the air within the hollow volumes but effectively transporting it to sections with hollow volumes where it is not felt by the user or to the outside air. The form factor of the invention is a band, as this is a form which is flexible in both dimension. Even though an electrically conducting layer is used in the invention a band is usually bended only in one direction (along the length) as the width is too short to bend the material. A band can also affect larger sections within a mattress, as several bands can be used with distance between it, so that moisture or humidity can pass easily between the bands.
[0039] The band has an electrically conducting layer and has therefore a high thermal conductivity. This parameter is not enough to really transport thermal energy, but it is necessary for function. Usually materials with carbon content are preferred, like graphite, but also other material, such as but not limited to copper or aluminum, could be used. To achieve some kind of flexibility the thickness of the electrically conducting layer needs to be reduced to below 0.5 mm, but higher thickness is also allowed in this invention as long as a certain flexibility is achieved.
[0040] This electrically conducting layer within the band has to be uninterrupted, meaning thickness, composition and width need to be above the minimum values along the whole length of the band. This condition is most important. Only by connecting the electrically conducting layer based on this principle a consistent flow of thermal energy can be observed in case also the following condition is met.
[0041] The last condition is the positioning of the band in a way that it touches the hollow volumes in section with excessive thermal energy i.e. direct under the body or any heating device and at the same time also touches uninterrupted at least one hollow volume in a section with normal or reduced thermal energy. These sections can be found in any mattress.
[0042] The sections of lower thermal energy are the left and right side of the mattress, or the feet portion. If the mattress is placed on a surface allowing air to reach the lower side of a mattress (i.e. slated frame, spring box) also this lower side can be used. There are two principles governing this invention. [0043] 1. The higher the difference of thermal energy content between both sections the better the thermal energy flow. As the thermal energy below the body is rather fixed it is worthwhile to search for section with lower thermal energy carefully. Some of the variations described below are based on lowering the thermal energy level in those sections. [0044] 2. The larger the section of the band is in a section of the mattress with lower thermal energy content in relation to the section of the band in a section of the mattress with excessive thermal energy the better the thermal energy flow. Therefore, the invention recommends that at least 30% of the band is in a section with lower thermal energy, but 50% would be preferred, especially if the temperature difference is not really large.
[0045] The effects of this invention can be clearly measured.
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[0049] The band itself is small and therefore not a blockade to humidity passing through the mattress. But if the humidity should pass through the band this can be punctured well with holes in regular patterns. The thermal energy flow will pass around these holes and not be interrupted. The puncture can be so dense that it is similar to a perforation which is also allowed within this invention. It is recommended to keep the holes as small as possible.
[0050] A band being flexible and consisting purely from electrically conducting material will typically be sensitive to punctual impact and react with break. The break should be especially avoided as this creates an interruption of thermal energy flow. It has been found that a laminating of a very thin PE layer (<0.18 mm thickness) is enough to prevent a break of the band. This lamination can of course also be applied on both sides but usually this is not necessary. Also, other material adding stability can be applied as long as it is flexible i.e. Polyurethane.
[0051] The band connecting the two sections with excessive and lower thermal energy can pass through or end in a section of the mattress filled with gel infused foam. Gel infused foam (“Gelfoam”) is usually used to prevent the user from feeling too hot, so it answers a similar question. But typically, the invention described in this document creates a much higher thermal energy flow than gel infused foam. This combination adds up the thermal capabilities of the gel infused foam and of the band described in this document.
[0052] A further variation is based on the observation that the thermal energy level in the section with lower thermal energy should be as low as possible. It might be that based on the specific shape of the mattress even this section is penetrated by thermal energy from the body. So, any thermal shield (insulating layer) between said section and the body would lower the thermal energy level in that section, increases the thermal energy difference between said section and the section of excessive thermal energy and therefore increases flow of thermal energy within the band.
[0053] The band can be positioned purely within the mattress, but it can also be positioned that the band runs from the section of excessive thermal energy outside the body, i.e. along a side or the lower side of the mattress or completely outside (i.e. from the mattress into a spring box below). Typically, the outside thermal energy level is determined by room temperature this temperature being much lower than the temperature of sections of excessive thermal energy. It could be observed that this difference in thermal energy level is large enough to create a superior flow of thermal energy through the band. A section of the band of 20% outside the mattress or along the side of the mattress is more than enough to increase the flow of thermal energy to an optimal value.
[0054] The band described should have a thickness between 0.1 mm to 0.5 mm. A thin band is more flexible but also more sensitive to break whereas a thicker band is the opposite. Also, the capacity of the band to absorb and transport thermal energy can be affected by the thickness of the band.
[0055] The band was observed to fit well into a mattress if the width is between 4 cm to 10 cm, though also smaller or wider dimensions are allowed. In case wider dimensions are used the puncturing or perforating variation is preferred as not to reduce humidity flow within the mattress.
[0056] Most superior thermal effect of the band was observed when using graphite as the electrically conducting layer of choice. As graphite comes in very different variations good results were achieved using graphite with a carbon content greater than 99% and/or a content of ash lower than 1% and/or a density of greater than 1 g/qcm and/or a content of Sulphur lower than 1.800 ppm.
[0057] Also, there are very different types of graphite available. The type called highly oriented pyrolytic graphite (HOCG) is very capable to transport thermal energy based on the special molecular structure. Highly oriented pyrolytic graphite (HOPG) is a highly pure and ordered form of synthetic graphite. It is characterized by a low mosaic spread angle, meaning that the individual graphite crystallites are well aligned with each other. The best HOPG samples have mosaic spreads of less than 1 degree. It had been found that this graphite type is generating very good results in transporting thermal energy.
[0058] In another version of the invention the electrically conducting layer is made from graphene. This material has an allotrope of carbon in the form of a two-dimensional, atomic-scale, hexagonal lattice in which one atom forms each vertex. It is the basic structural element of other allotropes, including graphite, charcoal, carbon nanotubes and fullerenes. It can also be considered as an indefinitely large aromatic molecule, the ultimate case of the family of flat polycyclic aromatic hydrocarbons. As graphene has a thermal conductivity of greater than 1.000 W/mK it can be much smaller than a flexible band with an electrically conducting layer of normal graphite having with the same thermal performance.
Embodiments
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REFERENCES NUMERALS
[0069] 10 Padding [0070] 12 First hollow volume (with excess thermal energy) [0071] 14 Second hollow volume (without excess thermal energy) [0072] 20 Flexible Band [0073] 22 Electrically conducting layer on flexible Band [0074] 24 Lamination on flexible Band [0075] 30 Mattress [0076] 32 Section with excessive thermal energy [0077] 34 Section without excessive thermal energy [0078] 36 Top Foam Layer of a mattress [0079] 38 Section of mattress with Gel-infused foam [0080] 40 Bed [0081] 42 Box spring base of a Bed