Recirculating air snow melting pad system

A recirculated heated air mat system melts snow and ice from driveways or roofs, preventing its accumulation. The driveway sized, hollow mat of tough, pliable rubber, plastic is resistant to tearing and abrasion. A recirculating air electric heater provides heated air to the mat. The mat contains baffles directing heated air sinuously through the substantial portion of the mat, and an internal wall forms a cooled air return path along the upper end for recirculating the air to the heater. For a two-car garage, two pads are provided. The second pad may be identical to the first pad. Heated air is directed between the first and second mats and returned through the cooled air return path by separate removable ducts between heating air paths and cooled air return paths. The system may be modular, being assembled from identical mats and ducts. A large single mat for a roof is provided.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to snow and ice melting equipment. More particularly, the present invention relates to equipment for maintaining sidewalks, driveways, and roofs free of ice and snow.

2. Description of the Related Art

The use of heating coils or the like to maintain surfaces such as sidewalks, driveways, and roofs free from buildup of ice and snow is known. Commonly used devices include steam or hot water heated coils within or underneath the surface material such as concrete or the like. Also known is the use of electrical resistance heating systems including mats for placement over the surface to be cleared having resistance heating elements therein. In some applications resistance electrical heating mats are uneconomical. It would be desirable to provide an alternative mat type system which may use recirculated heated air and which may be placed on the surface to be kept clear of snow, such as a driveway, and is sufficiently sturdy to walk or drive a car over without damage.

U.S. Pat. No. 223,784, issued Jan. 20, 1880, to Watson, describes a sidewalk having a fluid circuit of tubes under the surface for conveying steam for heating the sidewalk to prevent snow and ice from accumulating on the surface.

U.S. Pat. No. 3,818,892, issued Jun. 25, 1974, to Von Kohorn, describes a system for removing snow and ice from an athletic playing surface where heated air is circulated beneath the surface and up through the porous playing surface.

U.S. Pat. No. 4,270,596, issued Jun. 2, 1981, to Zinn et al., describes a heat exchanger for use in embedded radiant heating systems including a plurality of webbed tube mats and associated manifolds.

U.S. Pat. No. 4,646,818, issued Mar. 3, 1987, to Ervin, Jr., describes heated mats for melting snow and ice from walkways, driveways, and sidewalks employing tubing carrying a heated mixture of water and antifreeze.

U.S. Pat. No. 5,003,157, issued Mar. 26, 1991, to Hargrove, describes a snow melting pathway mat apparatus which is electrically heated and includes hollowed channels extending longitudinally along the mat, allowing melted snow to flow off the mat.

U.S. Pat. No. 5,591,365, issued Jan. 7, 1997, to Shields, describes a lattice-like heating mat having electrical resistance heating wire extending through the lattice, the lattice configuration allowing flexibility in conforming to uneven surfaces and for rolling up for storage.

None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus a mat system using recirculated heated air to melt snow solving the aforementioned problems is desired.

SUMMARY OF THE INVENTION

The mat system of the present invention employs recirculated heated air to melt snow and ice from walkways, driveways or roofs, preventing its accumulation on these surfaces or the like. In the driveway configuration, a mat is provided of appropriate size having upper and lower walls made of tough, pliable rubber, plastic, or the like which is sufficiently resistant to tearing and abrasion to withstand walking or driving a car over the mat. A recirculating air electric heater provides heated air to the interior of the mat. The mat contains baffles to form heated air paths to direct the heated air sinuously through the substantial portion of the mat, and an internal wall forms a cooled air return path along the upper end for recirculating the air to the heater.

For a two-car garage, two pads are provided. The second pad may be identical to the first pad. Heated air is directed between the first and second mats for sinuous flow therethrough and returned through the cooled air return path by providing separate removable ducts between heating air paths and cooled air return paths. The mat system in a preferred form is modular, being assembled from identical mats and ducts so as to provide any desired number of melting mats to cover a driveway for two or more cars or a flat roof. A large single mat for a roof is provided employing an industrial-sized electrical recirculating air heater employing commercial electrical power.

These and other aspects of the present invention will become readily apparent upon further review of the following specification and drawings.

Similar reference characters denote corresponding features consistently throughout the attached drawings. The features of the drawings are not necessarily drawn to scale but are for illustration only.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is a mat system employing recirculated heated air to melt snow and ice from walkways, driveways or roofs, preventing its accumulation on these surfaces or the like. In the driveway configuration, a mat is provided of appropriate size having upper- and lower walls made of rubber, plastic, or the like which is sufficiently resistant to tearing and abrasion to withstand walking or driving a car over the mat. A recirculating air electric heater and blower provides heated air to the interior of the mat. The mat contains baffles to form heated air paths to direct the heated air sinuously through the substantial portion of the mat, and an internal wall forms a cooled air return path along the upper end for recirculating the air to the electric heater and blower. The mat system may be modular, assembled from identical mats and ducts so as to provide any desired number of melting mats to cover a driveway for two or more cars or a flat roof. Another embodiment provides a single, large heating mat for use on a roof of a commercial building or the like and employs an industrial sized heater and blower which may use commercial electrical power such as 220 or 440 volt power.

Referring to the Figures, melting pad system10is shown installed on a concrete or asphalt driveway D (seeFIG. 1) leading from street S and garage door GD. A sidewalk SW is shown in a typical location and is cleared by the melting mat system10. A lawn L is located on each side of the driveway D. The system10may be expanded to include multiple pads for melting snow from larger areas (seeFIGS. 3–6) to cover multiple car driveways and flat roofs.

Referring toFIGS. 1 and 2there are shown an environmental perspective and a plan view of the preferred embodiment of the present invention showing the basic arrangement of parts of the melting pad system10, including electrically operated recirculating air heater and blower unit12of conventional design having a heated air supply conduit14connected with an outlet16of unit12and a cool air return conduit18connected with an inlet19of unit12. Melting mat20is generally rectangular in shape and has a mat upper wall22, first and second sidewalls24, lower wall26, upper end wall30and lower end wall34. Conduits14and18are preferably connected to the first sidewall24. Driveways D are typically sloped upward from the level of street S to the garage door GD to keep rainwater from draining into the garage and the melting mat system10is defined relative to this configuration of driveway. Melting mat20defines an upper end portion28for receiving and returning air from recirculating air heater and blower12, which is most conveniently located near the garage or house. A lower end portion32is located at the driveway entrance as shown, however the melting mat20may be of any desired length. For example, end wall34may be located short of the sidewalk SW.

Tie-down stakes36are conveniently spaced along the sides of driveway D and driven into lawn L and provide for anchoring of mat20by means of connecting ties38, preferably of elastic material, to sides22of anchor mat20for securing mat20in position during high wind conditions.

Upper end portion28of melting mat20has mat heated air inlet port40and mat cool air outlet port42along each sidewall22for interconnection with conduits14and16, respectively, and heated air and cold air return connecting ducts10and72, respectively (seeFIGS. 4–6).

The melting mat20has parallel, spaced traction treads44on its upper wall22having a rough or ribbed surface extending the substantial length of mat10so as to provide traction for vehicle tires as a vehicle is driven into the garage with the garage door GD lifted. Non-skid material such as waterproof grit covered sheet material45(seeFIGS. 2A and 2B) may be applied to the upper wall surface in tracks up to 3 feet wide or more to provide for additional vehicle tire traction or footing, the material conforming to the airflow tube and drain channel features (see discussion below). Non-skid material may also be used to cover the lower surface of the lower wall26of mat20. The vehicle would not normally be parked on the mat20since its weight could block circulation of air through the mat system.

Mat20incorporates wind relief tubes46therethrough opening between upper and lower walls22and26in surface areas other than the traction treads44and which allow wind to pass through the mat20when lifted by a cross wind, thereby aiding in maintaining the mat in its location on the driveway D. The relief tubes46are preferably spaced in rows parallel with sidewalls24, each row being surrounded by raised strips47extending along each row rising upward from upper wall22to minimize water drainage into tubes46. Water drain channels48extend along the substantial length of mat20and allow water from melted snow to drain off the pad20, thus avoiding refreezing of the melted snow and clogging of wind relief tubes46. The diameter of relief tubes46and width and depth of water drain channels48may be selected depending local weather conditions, the thickness of the mat, and the thickness of the upper wall material forming the mat20.

FIG. 2Bshows an alternative embodiment of the invention where only a single snow melting mat20is contemplated. In this embodiment the second sidewall24opposite the first sidewall24having heated air inlet port40and cool air outlet port42extends upward to meet upper wall30.

As best seen inFIG. 3A, heated air is maintained separate from cool return air by air return wall60. Heated air introduced through heated air inlet port40is directed sinuously through the substantial portion of mat20by alternating upper wall baffles62extending lengthwise from air return wall60and lower wall baffles64extending lengthwise from lower end wall34, forming sinuous path66. Cooled air is returned for heating and recycling in unit12by along cool air return path68formed by cool air return wall60and upper end wall30and the upper and lower walls of mat20. Elbow duct50connects heated air exit port52to cooled air return port54for return of the circulating air along cool air return path68. Wind relief tubes46are preferably located in rows within sinuous path66, centered between baffles62and64, respectively.

Referring toFIG. 3B, there is shown a section view of the embodiment ofFIG. 2B, wherein inner cold air return wall60ends at upper wall baffle62providing an internal return port61for directing cooled air for return to mat cool air outlet port42from the opposite mat side wall24.

As best seen inFIGS. 3–5, multiple snow melting mats20may be interconnected by cool air return connecting ducts70and heated air connecting ducts72. Cool air return connecting ducts70connect cool air outlet port42to cooled air return ports54. Heated air connecting ducts70connect heated air exit ports52with mat heated air inlet ports0.40. Connecting ducts70and72may be identical in configuration. The last of the series of mats20may be identical to that of the first mat20, employing elbow duct50for recirculating air through the mat system. Alternatively, the last of the series of mats20may be configured as shown inFIGS. 2B and 3Band elbow duct50is not required for operation of the mat system.

Referring toFIG. 6A, there is shown another application of the recirculating heated air snow melting mat system10of the present invention where melting mats20are installed on the flat roof R (slightly sloping for drainage) of a commercial building. The building has a cornice C and overlooks a sidewalk SW and a street S for travel of automobile A. The mat system10is installed such that water drains from cavities48along the slope of the roof R to drains DR in roof R. The ties38may be tied to stakes36installed in receiving tubes (not shown) or tied to eyelets or other connecting support structures of known type and design.

As shown inFIG. 6B, the mat system10may employ a single large mat90of greater width relative to length, as desired, the number of heated air baffles being increased (not shown) for distribution of heat over the wide mat. The roof R is shown as that of a commercial building B, the roof being substantially flat or slightly sloped and having drain holes DR. A sidewalk SW surrounds the building B next to which an automobile A is parked on street S. A single large mat substantially covering roof R may be tied securely to two or more walls of cornices C by ties to anchor bolts92. Recirculated heated air is provided by an industrial sized electrical unit through heated air supply conduit14from cool air return conduit18in a manner similar to that of the driveway mat20. The mat is oriented such that it drains toward drainpipes DR.

The mat90may also be installed on a sloping roof (not shown) if properly sized and tied down. A 220-volt AC heater and blower may be useful in this application. In a similar manner, a single mat90of having a double or triple width (not shown) may be used for a double or triple car driveway as desired and may include corresponding pairs of traction treads44thereon.

Referring toFIG. 7A, there is shown a side view of the upper end portion28of the snow clearing mat20showing heated air inlet port40and cool air outlet port42having covers82in the uncovered and covered positions, respectively. The covers are useful for storage purposes to prevent the entry of pests, dirt and debris into disassembled and stored system. The covers82may be hinged to the sidewall24by integral hinge83as shown for port40or be provided as a separate component of the system10. The covers82are preferably removably connected to the sidewall24by hook and loop material (Velcro). As shown, port40is surrounded by hook material84and the border of cover82covered with loop material86. For port42the engaged hook material is covered with loop material86(hidden lines) of a cover82.

Referring toFIG. 7Bthere is shown an end view of a connecting duct70having ends88surrounded by loop material86for connection with hook material84of heated air inlet port40and cool air outlet port42. Ducts70and72have identical ends88having loop material86for connection with heated air exit port52and cooled air return port54.

Referring toFIG. 7Cthere is shown an end view of elbow duct50having elbow air inlet55for mating with mat heated air exit port52and elbow circulating air outlet57for mating with mat cooled air return port54, respectively. Elbow air inlet55and elbow circulating air outlet57each have loop material86for connection with corresponding hook material84of heated air exit port52and cooled air return port54, respectively.

The hook material84and loop material86(Velcro) may be interchanged between ducts the50,70, and72and the heated air inlet and exit ports and the cooled air inlet and exit ports of mat20as desired. The configuration of the mat connecting ends of heated air supply conduit14(seeFIGS. 1 and 2) and cool air return conduit18may be identical to that of ducts70and72employing hook material and mating loop material (not shown) for removable connection therewith in the same manner.

The material of the inventive snow-melting mat is preferably a lightweight, tough, pliable plastic or rubber material. The mat is preferably from about 1″ to about 2″ in overall thickness. Each driveway mat20is preferably about 10 feet in width and of a length of from about 20 to about 30 feet in length. The single roof type mat may be from about 50 to 100 feet in width and from about 50 to 150 fee in length. The electrically powered heater and blower for the single roof type mat may be powered by 110, 220, or 480 volt electrical current.