GB2542616A

GB2542616A - Tent with heat-limiting properties

Info

Publication number: GB2542616A
Application number: GB1517053.3A
Authority: GB
Inventors: Price Gareth
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-09-26
Filing date: 2015-09-26
Publication date: 2017-03-29
Also published as: GB201517053D0

Abstract

A tent 2 comprises a frame for defining a tent shape; a fabric shell 2 to be supported by the frame and for defining an enclosure, the enclosure comprises at least a wall; and at least one fan 8 located in an opening in the fabric shell for effecting movement of air between the enclosure and the outside of the fabric shell. Additionally, a fabric fly sheet 4 is present, whereby a duct 10 connects a fly opening 16 with the fabric shell opening so that air moved by the fan is not impeded. Alternatively the fan may be located in the opening of the fly. Preferably a mesh insect screen 20 is located over the fly opening and/or with vents 12. The fan is preferably detachable with fixing means such as hook and loop type. The fly or fabric shell may include a radiant barrier such as a reflective coating.

Description

Tent with Heat-Limiting Properties

Background

Originally made from animal skins, tents have been around for thousands of years. Since the 1970s, lightweight synthetic materials such as nylon and polyester have become very popular in tent manufacturing. This is primarily due to the combination of favourable characteristics, including being: • Low cost • Strong • Lightweight • Abrasion resistant • Easily treated or coated to improve properties such as water resistance

These thin, lightweight, synthetic fabrics also absorb, transmit and re-emit solar radiation very well. This causes a “greenhouse effect” inside the tent, which is a well-known source of discomfort and frustration for campers when camping in sunny or otherwise hot weather.

Despite this issue having been known for over forty years, no product exists that addresses the issue.

In sunny weather, the effect of solar gain on a tent will often render it too hot to occupy. Lightweight tents made from synthetic materials such as polyester and nylon are particularly susceptible to this problem, but canvas tents are also affected.

Users of tents often attempt to mitigate this problem by shading their tent with another apparatus such as a tarpaulin, awning or purpose-built shade structure. Another common DIY approach is to cover part of the tent with reflective ‘emergency blankets’ (Mylar is a well-known brand of reflective film used to make such blankets). Such methods have numerous drawbacks as they either require additional, often bulky, equipment to be carried or, in the case of emergency blankets, are difficult to attach to the tent, and easily ripped or damaged by wind.

Furthermore, unless the entire tent is covered or shaded, solar gain will still act on the unprotected area of the tent. As the angle of the sun changes throughout the day, complete shading is generally impractical when camping. Nor is it practical to cover completely a traditional tent in reflective sheets such as ‘emergency blankets’ as doing so would greatly reduce ventilation and prohibit entry to and exit from the tent. A further attempt to cool a tent has been simply to leave the “door” open. However, this attracts unwelcome guests in the form of insects at least and does not necessarily provide movement of air if there is no breeze. Vents are often provided in modern tents but again these do not guarantee a breeze and therefore do not guarantee cooling of the tent when it is heated by the sun.

Description

It is an object of the present invention to address the problem of increased temperature in tents caused in particular by solar radiation on the tent fabric.

According to a first aspect of the invention, there is provided a tent, comprising: a frame for defining a tent shape; a fabric shell to be supported by the frame and for defining an enclosure, the enclosure comprising at least a wall; and a fan for positioning in an opening in the wall of the fabric shell for effecting movement of air between the enclosure and the outside of the fabric shell. The advantage of having a fan in the wall of the tent is that it enables ambient air to be drawn directly into the inner tent, thus cooling the inner enclosure. A key advantage of the presence of the fan (or fans) is to be able to keep the tent cool whilst the doors are closed, keeping the tent dark whilst a person is sleeping inside, improving privacy and security and preventing the ingress of insects.

There may further be provided a fabric fly also known as a “fly sheet” or just “fly” for erecting outside and at a predetermined separation from the fabric shell, the fabric fly including an opening which, when the fabric fly is erected outside the fabric shell, is substantially aligned with the opening in the wall of the fabric shell; and there is preferably a duct for attaching between the opening in the wall of the fabric shell and the opening of the fabric fly. The opening in the fly and the duct joining the two openings enables air to be drawn in with minimal impedance. The opening of the fabric fly may be substantially the same size as the opening of the fabric shell or it may be larger than the opening in the fabric shell to allow greatest air intake. It is desirable for there to be an insect screen for covering the opening of the fabric fly to prevent insects from being drawn in along with the air.

According to a second aspect of the invention, there is provided a tent that has the fan in the fabric fly rather than in the fabric shell, though the duct between the two openings may be the same. This may be effected by a reversible duct-and-fan system that may be fitted with the fan in either the fly or the tent wall, depending on position of power source, for instance. The power source may be inside or outside the tent and may be at least one from a group containing at least: a. a USB-compatible portable battery pack, b. a portable solar panel with USB or 12V output, c. a car cigarette-lighter socket, and d. clips direct to 12V battery terminals, such as a car battery.

The fan is preferably detachably attached to the fabric and may be a zipper or a hook-and-loop fastener. The detachability enables more efficient packing of the tent.

There may be two or more fans that may be opposite each other to effect a through-draft through the tent. One of the fans may be replaced by a vent as long as the remaining fan or fans enables the through-draft.

The fabric shell - or the fly if present - preferably comprises a radiant barrier outer surface which may be a reflective coating that reflects infra-red radiation. This has the advantage of minimising solar heat gain in the enclosure of the tent. Alternatively, the fabric shell or fly may have a radiant barrier inner surface. The radiant barrier coating preferably used has low emissivity so it does not radiate heat into the tent even if it is on the inside of the fabric shell or fly.

According to a third aspect of the invention, there is provided a fan suitable for use in a tent wall, the fan comprising attaching means at its periphery for attaching to an opening in the tent wall.

The present invention will now be described purely by way of example and with reference to the figures, in which:

Fig. 1 shows a cross-section of a tent including a fan in the inner tent and a duct between the inner tent and an opening in an outer fly; and

Fig. 2 shows a perspective view of the fan from the inside of the inner tent.

In order to reduce the heating of the inside of a tent, the following will describe two partial solutions: 1) Solar-reflective, radiant barrier (fly) fabric, to minimise solar heat gain; and 2) Integrated electric fan, to draw air at ambient temperature directly into the inner tent.

The integrated fan will be discussed first as it is the main subject of the preferred embodiments. 1) Electric fan integrated into the wall of a tent

Figure 1 shows a cross-section of a tent 2 surrounded by a fly 4, the fly having openings or vents 12. A particular opening 16 in the fly 4 is connected by a duct 10 to an opening in the tent 2 in which the fan 8 is positioned. The duct 10 is optional but preferred and is detachably attached to the inner tent by attachment means 14. The fan 8 is detachably attached to the inner tent 2 by attachment means 22 such as a zipper or hook-and-loop fastener. The fan could be integral in the tent wall but making it detachable enables easier packing away of the tent and potentially makes the fan optional for cooler-weather camping. For this purpose, there may be a simple flap or piece of fabric that may cover the opening when the fan is not in use. The opening 16 of the fly 4 is preferably covered by an insect screen or mesh 20.

Specifically, to reduce further the impact of solar gain on the temperature inside a tent 2, the design integrates the electric fan 8 in such a way as to draw air from outside the tent directly into the sleeping area inside the tent 2.

Figure 2 shows a view of the fan 8 from inside the inner tent 2. The flexible material 18 of the duct 10 enables the opening 16 in the fly 4 to be aligned with a useful tolerance. A detachable attachment 22 attaches the fan 8 to the inner tent 2 and a separate detachable attachment 14 attaches the duct 10 to the inner tent.

The choice of fan is based on the following criteria: a) Low power consumption to prolong battery life; b) Low noise so as not to disturb sleep; and c) Sufficient air flow to exchange the volume of air inside the inner tent 2 every one to two minutes.

The technical specifications of the fan utilised fora prototype made by the inventors are as follows:

Diameter: 200 mm (millimetres)

Air flow: 110 CFM (cubic feet per minute) or 0.05 cubic metres per second Noise: 19 dBA (decibels: acoustic)

Power Consumption: 1.8W (Watts)

The fan can be powered by: a. A USB compatible portable battery pack, such as it popular for charging mobile phones and tablets. Such devices are commonly referred to as a ‘power bank’ and utilise a rechargeable lithium battery; b. A portable solar panel with USB or 12V output; c. A car cigarette-lighter socket; or d. Clips direct to 12V battery terminals, such as a car battery.

Other power sources such as solar panels that charge a battery or directly run the fan when the sun rises can be imagined by the person skilled in the art.

The diameter of the zippered opening in the inner tent is 300 mm in the prototype. The opening of the inner tent may of course be larger or smaller than this, depending in part on the size of the tent and the requirements of the fan (e.g. larger fan to cool larger tent).

The diameter of the mesh-covered opening in the fly is 400 mm in the prototype. The additional surface area of insect-mesh minimises reduction in air flow of the opening in the fly caused by the mesh.

The opening is positioned approximately 3/4 of the way up the side of the tent. This has the advantages of: a. Minimises distance between fan opening and poles, providing better support for the fan assembly; b. Improves air circulation as cooler air falls, and the draft is angled slightly downwards towards the occupant(s); and c. Keeps the fan clear of obstructions such as bags and bedding.

The duct walls 18 may optionally contain flexible plastic rods to help maintain the shape of the duct.

The prototype design uses a zip to connect the fan unit to the tent wall, however a hook-and-loop fastener such as Velcro, or similar fastener, may also be used in place of the zipper.

The innovation is to mount the fan within the wall of the tent, and in the case of a double-walled tent, to connect a fabric duct 10 between an opening 16 in the fly 4 and the fan opening of the inner-tent 2 such that only ambient air from outside the fly is drawn in by the fan. However, the fan may be used without a duct and it may take in air from between the fly and the inner tent fabric shell as well as ambient air from outside of the fly.

The duct opening on the fly is covered by a hood 12, made from the same reflective fabric as the fly (described later), which reduces the effect of solar radiation heating the tent via the fan opening.

In order to prevent insects from entering the tent via the fan opening, the fly fabric has an insect mesh 20 incorporated across the opening through which air is drawn by the fan.

In the case of a double-walled tent (fabric shell plus fly), in order to minimise any reduction in airflow through the fan that may be caused by the insect mesh, the fan is more preferably integrated into the wall of the inner tent rather than into the fly our outer wall of the tent. This allows for a larger surface area of insect mesh to be used across the opening in the fly to allow the same effective opening cross-section for both the fly opening 16 and the tent opening despite the insect mesh 20. For example, in a preferred configuration the fan diameter is 200mm and the opening in the fly (covered by insect mesh) is 400mm (assuming that the insect mesh has a ratio of 50:50 mesh area to hole area). Thus the duct is a slightly funnel shaped with the narrow end inside and the wide end on the fly. Of course, the opposite is possible in which the fan is in the fly and the opening in the inner tent may be a size to enable most efficient airflow. Alternatively, the two openings may be the same size or sized differently to allow a desired airflow.

The fan is a small, lightweight unit, up to 300mm in diameter in preferred configurations. In tests, fans of 140mm and 200mm diameter gave excellent results. The fan operates from any suitable power supply including solar panels (including photovoltaic cells) or a 12v DC power supply provided by a car outlet, or an external battery pack or other source.

According to an alternative embodiment, there may be two or more fans installed in the tent wall. In tests, the use of one or two fans (where a fan is installed on each side of the tent) was able to maintain an inside temperature no more than 2 to 3 degrees Celsius warmer than the outside ambient air temperature. This is far better than the “greenhouse effect”, which causes much higher temperatures inside the tent.

An alternative configuration has the fan pulling air from inside the tent to the outside. A separate vent, as is usually supplied in tents, is thus needed to allow air in to replace the air being pulled out by the fan.

Whilst there are many products on the market known as ‘tent fans’, none of these products are designed with air intake or extraction in mind. They simply circulate the air inside the tent, but do not act in a way that draws fresh air into the tent, or that extracts warm air out of the tent.

The innovation of building a fan-mounting mechanism directly into the wall of the tent has not been seen previously. 2) Solar-reflective, Radiant-barrier Fly 4

The solution described herebelow directly tackles the problem of heating in tents by developing a new type of tent fabric: one which exhibits all the desirable characteristics of a traditional synthetic tent fabric, but adding a very thin solar-reflective layer to reflect the sun’s energy away from the tent and prevent the greenhouse effect from occurring.

The fly 4 fabric is comprised of a lightweight fabric such as polyester, nylon or canvas, with a solar-reflective film or coating 6 applied to the outwardly-facing side. The coating or film has a low emissivity so that it acts as a radiant barrier, reducing solar gain from infrared thermal radiation, in addition to reflecting UV and visible light wavelengths. The coating or film may equally be in the inwardly-facing side to provide the same benefits of not radiating heat energy into the tent. An example of the fly fabric may be white or otherwise reflective on the outside and a radiant barrier on the inside.

The application of a solar-reflective, radiant-barrier fly fabric has not previously been seen in the field of tent fabrication. For this innovation, the outside surface of the fly fabric can either be laminated with a reflective film, or a metalized aluminium-based coating can be applied directly to the fabric. Aluminium is typically used in such applications due to its high level of reflectivity across a broad spectrum of wavelengths, in particular the range of solar radiation.

In order to develop the innovative fly fabric, the inventors used film, lamination, and coating technology known in unrelated fields, particularly the manufacture of insulation materials and food packaging. Such manufacturing processes can be adapted to apply very thin film or coatings to a lighter weight of fabric than would typically be used in those fields, thus creating a fabric that is suitable for tent fabrication.

The underside of the fabric is coated with a layer of Polyurethane (PU) to prevent water from soaking into the fabric, and to enable the tent seams to be sealed using PU tape, which is applied using heat via a seam-sealing machine which is well known in the manufacture of tents.

Whilst simple in concept, the innovation requires the adoption of knowledge and technology from other industries. The manufacturing process used to make the fabric is typically used for fabricating thermal insulation materials.

The adoption of such technologies is an innovative step, which has not been made in over forty years of synthetic tent manufacturing.

Tents produced with such a coating are significantly more comfortable for those dwelling within than comparable tents fabricated using traditional fabrics, when exposed to direct sunlight.

The effect of a fan without the reflective fly makes a first level of improvement in the comfort of the occupant compared to tent fans already on the market. Adding the reflective fly makes a second, greater level of improvement in the comfort of the occupant. This is due to the significant amount of solar heat gain and transmissive nature of typical tent fabrics. The heating effect of a tent without the reflective fly is too great for a small fan to counteract completely. Thus, a combination of reflective material plus fan or multiple fans is desirable.

To be effective, the fan may have a dependence on the reflective fly fabric. It would therefore not be an obvious innovation for a traditional tent design on its own.

When used in combination with the reflective fly fabric, the fan is able to exchange sufficient air to maintain the temperature inside the tent at, or very close to ambient temperature (typically less than 3 degrees Celsius difference from the ambient temperature as measured in tests using a 200mm fan as described above). This makes a significant contribution to the comfort of the occupant.

Claims

1. A tent, comprising: a frame for defining a tent shape; a fabric shell to be supported by the frame and for defining an enclosure, the enclosure comprising at least a wall; and a fan for positioning in an opening in the wall of the fabric shell for effecting movement of air between the enclosure and the outside of the fabric shell.

2. A tent according to claim 1, further comprising: a fabric fly for erecting outside and at a predetermined separation from the fabric shell, the fabric fly including an opening which, when the fabric fly is erected outside the fabric shell, is substantially aligned with the opening in the wall of the fabric shell; and a duct for attaching between the opening in the wall of the fabric shell and the opening of the fabric fly.

3. A tent according to claim 2, wherein the opening of the fabric fly is substantially the same size as the opening of the fabric shell.

4. A tent according to claim 2, wherein the opening of the fabric fly is larger than the opening of the fabric shell.

5. A tent according to claim 2, 3 or 4, further comprising an insect screen for covering the opening of the fabric fly.

6. A tent, comprising: a frame for defining a tent shape; a fabric shell to be supported by the frame and for defining an enclosure, the enclosure comprising at least a wall; a fabric fly for erecting outside and at a predetermined separation from the fabric shell; a fan for positioning in an opening in the fabric fly for effecting movement of air between the enclosure and the outside of the fabric fly; the fabric shell including an opening which, when the fabric fly is erected outside the fabric shell, is substantially aligned with the opening in the wall of the fabric fly; and a duct for attaching between the opening in the wall of the fabric shell and the opening of the fabric fly.

7. A tent according to any preceding claim, further comprising a power source for powering the fan, the power source being at least one from a group containing at least: e. a USB-compatible portable battery pack, f. a portable solar panel with USB or 12V output, g. a car cigarette-lighter socket, and h. clips direct to 12V battery terminals, such as a car battery.

8. A tent according to any preceding claim, further comprising attaching means for detachably attaching the fan to the fabric.

9. A tent according to claim 8, wherein the attaching means comprises a zipper.

10. A tent according to claim 8, wherein the attaching means comprises a hook-and-loop fastener.

11. A tent according to any preceding claim, comprising two or more fans.

12. A tent according to claim 11, wherein the two or more fans are opposite each other to effect a through-draft through the tent.

13. A tent according to claim 1, wherein the fabric shell comprises a radiant barrier outer surface.

14. A tent according to claim 1, wherein the fabric shell comprises a radiant barrier inner surface.

15. A tent according to any one of claims 2 to 6, wherein the fabric fly comprises a radiant barrier outer surface.

16. A tent according to any one of claims 2 to 6, wherein the fabric fly comprises a radiant barrier inner surface.

17. A tent according to claim 13, 14, 15 or 16 wherein the radiant barrier outer surface comprises a reflective coating.

18. A fan suitable for use in a tent wall, the fan comprising attaching means at its periphery for attaching to an opening in the tent wall.

19. A tent substantially as described herein and as illustrated in Figures 1 and 2.