Patent Application
20060088389
This invention relates to ground cloths for use between the ground and a ground engagable floor of a tent or similar enclosure for protecting the floor from dirt, abrasive wear and ground moisture.
Ground cloths formed of thin, flexible, light weight, easy to clean, waterproof (nonporous) sheets are known in the art for protecting tent floors from dirt, abrasive wear, and ground moisture. Such ground cloths are commonly sized slightly smaller than a tent floor, or footprint, so that moisture dripping down the sides of a tent will not land on exposed portions of the ground cloth and collect under the tent floor, between the ground cloth and the tent. With tent floors that are not entirely waterproof, such moisture tends to seep into the tent through the tent floor.
Ground cloths formed of Dupont Tyvek have also been proposed. Tyvek is a high-density polyethylene material that, while not considered to be strictly waterproof, is designed to resist water penetration. Consequently, it does not have the ability to quickly drain away the quantities of water that may accumulate during a rainstorm.
Conventional wisdom relative to tent ground cloths is that a ground cloth should be waterproof. However, a ground cloth capable of protecting a tent floor from dirt, abrasion and ground moisture, while also limiting the retention of moisture between the tent floor and the ground cloth, is desired.
The present invention provides an improved ground cloth formed of a thin, lightweight, easy to clean, durable sheet, that is adapted for use between the ground and a ground engagable floor of a tent, or the like, to protect the floor from contamination by the ground. The ground cloth includes a plurality of drain holes through the sheet adapted to drain moisture through the sheet to the ground to prevent the retention of moisture between the ground engagable floor and the ground cloth.
The number, size, arrangement and spacing of the drain holes may be constant or may vary depending upon the application. For example, the diameters of circular drain holes may vary in a range of from 0.1 mm to 3.0 mm and the spacing between the holes may vary in a range of from 2.5 mm to 50.0 mm so that the drain holes make up between 0.1 percent and 10 percent of the ground cloth surface area. In addition, the ground cloth may be sized having edge dimensions smaller or larger than edge dimensions of an associated ground engagable floor.
These and other features and advantages of the invention will be more fully understood from the following description of certain specific embodiments of the invention taken together with the accompanying drawings.
In the drawings:
The term ground cloth refers to a sheet of porous or nonporous material which, may be modified to include drain holes added after or included during manufacture. A ground cloth of this invention is primarily intended for use under a tent floor to protect it from contamination by dirt or moisture on the ground. It could also be used under ground engaging floors that are not part of a tent, such as a sleeping bag, screen house, storage unit or other portable or semi-portable enclosure.
The term generally nonporous material is intended to include materials that are waterproof (nonporous) or water resistant but permeable.
The ground cloth 10 has a sheet thickness, not shown, which may vary to provide suitable strength, flexibility and weight of the sheet material used to form the ground cloth. Any suitable plastic ground cloth material may be utilized, for example, polyethylene sheet having a thickness in a range of 2-10 mils. In exemplary embodiments, the edge dimensions of a rectangular ground cloth 10 range from 2 feet by 7 feet to 10 feet by 18 feet.
The edge portion 20 preferably has a drain hole area ratio that is 2 to 4 times that of the center portion 18 of the ground cloth. Thus, if the center portion 18 has a drain hole ratio of 1 percent, the edge portion 20 may have a drain hole ratio of from 2 to 4 percent.
It should be understood that the diameters D of the drain holes 14 and spacing S between the drain holes as illustrated in
Preferably, the surface area of the drain holes 14 should constitute between 0.1 and 10 percent of the total surface area of ground cloth 10 or 17. This ratio provides adequate moisture flow rates (greater than 10 mm of liquid per hour) to prevent the retention of moisture between the floor and the ground cloth while minimizing contact between the floor and the ground to reduce abrasive wear and dirt transfer to the tent floor.
In use, a ground cloth 10 or 17 is initially spread over the ground and a tent 22 having a floor 24 is erected over the ground cloth.
As the tent 22 is exposed to moisture in the form of rain or dew, the moisture tends to run down the sides of the tent, not shown, onto the ground surrounding the tent. However, a portion of the moisture draining from the sides of the tent 22, or flowing along the ground, may seep below the floor 24 and between the ground cloth 10 and the floor. As moisture travels between the floor 24 and the ground cloth 10, toward low spots in the ground, the moisture is drained through the drain holes 14 to the ground. This reduces moisture retention between the floor 24 and the ground cloth 10 and thereby minimizes moisture transfer through the floor.
In addition to the simple drainage of water through the drain holes, the holes enable a vapor transport mechanism to remove either residual moisture that remains after any bulk water has drained out, or ground moisture that may on occasion come up through the holes. The vapor transport mechanism is driven by a tent interior temperature that is greater than the ground temperature, a situation that will usually exist due to heat provided by one or more of the following elements—the sun, the atmosphere or tent occupants. The temperature gradient will generate a vapor pressure gradient across the ground cloth, and thus a flow bias that results in a net transport of moisture through the holes to the ground below. In spite of the presence of holes, a tent is therefore effectively isolated from ground moisture by the present invention.
As moisture first flows over the edge portion 20 of the ground cloth 17, the edge portion 20, having a higher drainage surface area, drains a majority of the moisture to the ground to reduce the likelihood of moisture reaching the center portion 18 of the ground cloth. The center portion 18 having less drainage surface area allows any errant moisture that has passed the edge portion 20 to be directed into the ground. The lower drainage surface area of the center portion 18 also minimizes contact between the floor and the ground to reduce ground abrasive wear and dirt transfer to the floor.
As the tent 22 is exposed to moisture in the form of rain or dew, the moisture tends to run down the sides of the tent onto the edge portion 20 of the ground cloth 17. The edge portion 20 having a higher drainage surface area extending beyond the edge of the tent, drains a majority of the moisture to the ground to reduce the likelihood of moisture reaching a center portion 18 of the ground cloth. The center portion 18 having less drainage surface area allows any errant moisture that has passed the edge portion 20 to be directed to the ground. The lower drainage surface area of the center portion 18 also minimizes contact between the floor and the ground to reduce ground abrasive wear and dirt transfer to the floor.
If desired, the circular drain holes, previously discussed, may be replaced with various other shapes, such as slits, squares, rectangles, polygons, ovals.
Although the invention has been described by reference to certain specific embodiments, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the described embodiment, but that it have the full scope defined by the language of the following claims.
