Electric heating – Heating devices – With heater-unit housing – casing – or support means
Reexamination Certificate
1998-08-06
2001-01-30
Walberg, Teresa (Department: 3742)
Electric heating
Heating devices
With heater-unit housing, casing, or support means
C219S213000
Reexamination Certificate
active
06180929
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to flexible electrical heating pads and more specifically to a flexible-heating pad adapted for outdoor use for melting snow and ice accumulations.
BACKGROUND OF THE INVENTION
Over the years there have been a number of attempts to melt snow and ice accumulations by heating the affected surface. Most past configurations required a permanent installation of the heating element inside the surface, as exemplified by Watanabe in U.S. Pat. No. 5,605,418 and Deschenes in U.S. Pat. No. 4,564,745. These solutions however tend to be expensive, are not readily adaptable to existing surfaces, and maintenance and repair often require destruction and reconstruction of the protected surface.
Several attempts at melting snow and ice accumulations by placing a heater on the surface of the area to be cleared have been made, as discussed below. Bayless et al. U.S. Pat. No. 4,967,057 teaches the use of multiple individual panels to cover varying size areas. The Bayless patent however calls for multiple connections between the separate panels, presenting potential failure points Additionally the panel may be dislocated and/or disconnected when driven upon. . The invention also requires a large number of panels to cover large areas and thus is less fitting for installation on driveways.
Another attempt by Shields, in U.S. Pat. No. 5,591,365 addresses those concerns by placing the heating element in a flexible lattice form. However the Shields invention uses a single series resistive element in the form of specialized and expensive heating cable distributed throughout the lattice. The use of a single series heating element prevents field customization of the heater to fit varying length of protected areas, and reduces reliability since a break in any point along the heater will render the whole apparatus inoperative.
Similar patents include Saylor in U.S. Pat. No. 5,614,292, Hargrove in U.S. Pat. No. 5,003,157, Spencer in U.S. Pat. No. 3,806,702, and Flynn Jr. in U.S. Pat. No. 5,637,247.
Patents such as U.S. Pat. No. 3,900,654 to Stinger have described heater elements allowing trimming to any desired length, comprising a thin, flexible laminated assembly of electrically conductive elastomeric material. In U.S. Pat. No. 4,523,085 Grise teaches a Flexible sheet film heating elements that comprises current feed electrodes, heretofore referred to as bus bars, disposed in parallel along two sides of the heater film. Multiple resistive ink patterns traversly connect between the bus bars to form an array of parallel connected heater elements. This arrangement allows for field customization of the heater length since the film heater may be cut anywhere between the parallel connected heating elements. However the Grise heater is not durable enough to sustain people or vehicular traffic or prolonged exposure to elements such as ultraviolet light ozone and other chemicals. Additionally when cut, the Grise heater does not offer submersion protection since the bus bars are exposed at the cut end.
All the above, taken individually or in combination do not teach the current invention as claimed. An inexpensive solution to the problem of snow removal by electrical means that is easy to install by untrained personnel, and that may be sold in roll form to allow cutting for any desired length in the field is therefor clearly highly desirable and is presented in the instant invention.
SUMMARY OF THE INVENTION
It is an object of the current invention to provide a safe, easy to install heating pad, primarily for de-icing and snow melting on driveways, walkways, stairs, ramps, rooftops and other similar surfaces requiring snow and ice removal. It is another object of the invention to create an environmentally sealed heating pad that may be exposed to the elements for an extended periods of time while applied to objects and surfaces requiring protection from snow and ice accumulations. It is yet another object of the invention to provide a heating pad which can easily be rolled up and stowed when not required.
Yet another object of the invention is to provide a heating pad for melting snow and ice that is easy to install, and can be field adjustable for application to driveways, stairs, ramps, rooftops, walkways and pathways of varying lengths. It is also an object of the invention to increase the traction of said driveways, ramps, walkways or pathways protected by the invention, and facilitate water drainage therefrom.
The present invention provides for flexible continuous heating pad comprising lower and upper abrasion resistant protective layers, and having a flexible electrical heater disposed therebetween. The upper and lower abrasion resistant layers protect the heater from the elements, provide environmental and mechanical protection to the heater, and make it durable enough to sustain frequent vehicular and human traffic. Thus the invention creates a portable heating pad easily applied to various surfaces to prevent ice and snow accumulations.
The present invention more specifically is a heating device for melting snow and ice which comprises a planar flexible electric heater including a plurality of resistive heating elements connected electrically in parallel and having two opposite planar surfaces. The device further includes at least two protective sheets composed of abrasion resistant flexible material, each having an inner surface oriented towards and in face to face adherent engagement with a respective planar surface of the plurality of resistive heating elements. The two protective sheets and electric heater disposed between the sheets form a heater assembly having two opposing end edges, and two opposing side edges. The electric heater further includes an elongated, flexible, electrically insulating substrate having an electrically insulated surface, and an electrical conductor disposed in proximity to each of the respective opposing side edges. The plurality of resistive heating elements includes a plurality of resistive material traces deposited on the substrate in spaced apart relationship, each of the traces being in electrical communication with the electrical conductors and extending therebetween. The respective inner surfaces of the protective sheets are laminated and bonded onto respective planar surfaces of the electric heater. Another embodiment is to mold the electric heater between said two protective sheets. At least one of the protective sheets includes an outer surface with a nonskid pattern impressed thereupon. A thermal cutout switch is preferably electrically connected in series with said electric heater for stopping the heating pad operation when the ambient temperature is above a predetermined level. Also included is an elongated sealing bracket having a substantially ‘U’ cross section forming an elongated opening dimensioned to receive the end edge of the heater assembly within the opening to protect the end edge from the environment and hazards due to submersion in water and of course, to prevent injury due to shock. The elongated sealing bracket is attached with sealing means for bonding the end edge of the heater assembly and for encapsulating the end edge. Positional stability is preferably enhanced with securing means such as tie downs or stakes located near the perimeter of the device. A benefit of the present invention is that the opposing side edges can be shaped to accommodate a curved walkway or driveway, or a walkway around a hot tub or similar curved area where snow and ice accumulation is nondesirous.
The heater is composed of an array of resistive heating elements electrically connected in parallel to each other. The heating elements generally traverse the longitudinal axis of the heater and thus the heater, and therefor the heating pad, may be cut to size in the field along a line separating the individual resistive elements.
It will be seen that the construction of the current invention allows for continuous production in roll form. This allows shipping and selling the invention in roll form and allows the customer to purc
Clearpath, Inc.
LaPointe Dennis G.
Mason & Associates, PA
Robinson Daniel
Walberg Teresa
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