Patent Description:
Planar electrical heating devices, such as thin-film heaters and thick-film heaters, are increasingly being used to address specific heating problems for various applications. For example, planar electrical heating devices find applications in diverse sectors such as aerospace, transportation, construction, chemical and food processing industries.

<CIT>) purports to disclose a grounded heated cover with a first pliable outer layer and a second pliable outer layer, wherein the outer layers provide durable protection, an electrical heating element between the first and the second outer layers, the electrical heating element configured to convert electrical energy to heat energy, a heat spreading layer, and a thermal insulation layer positioned above the active electrical heating element. The heated cover removes ice, snow, and frost from surfaces, wherein the heat generated penetrates soil and other material to thaw the material to a suitable depth. A plurality of heated covers can be connected on a single <NUM> Volt circuit protected by a <NUM> Amp breaker.

<CIT>) purports to disclose a lightweight flexible electrical heating device for melting snow and ice that may be cut in the field to custom length. The device includes a planar flexible electrical heater sandwiched between two vulcanized polymer protective sheets. The heater includes an array of resistive heating elements electrically connected in parallel and oriented substantially across the device length, allowing the heater to be cut to any length as needed.

<CIT> relates to a heating mat electrically connectable to a power source provided with a conductive prong connected to an electrical polarity defining a mat peripheral edge.

Industry has faced challenges in manufacturing and assembling large surface area planar electrical heating apparatuses as a replacement for electric heat trace cable with integral grounding layer for electrical safety. The grounding layer over large surface areas can be substantially thick in order to mitigate high leakage conductance. Manufactured planar heating elements are often permanent constructions, connections are made using round wire routed through on the exterior of the shell causing non-planar bulky constructions, connections are exposed without a grounding layer to cover them, and methods of assembly are often non-repairable, messy, and increase manufacturing and/or installation time.

The following introduction is provided to introduce the reader to the more detailed discussion to follow. The introduction is not intended to limit or define any claimed or as yet unclaimed invention. One or more inventions may reside in any combination or sub-combination of the elements or process steps disclosed in any part of this document including its claims and figures.

Various embodiments are described herein that generally relate to a planar electrical heating apparatus, an outer shell layer component for a planar electrical heating apparatus, an electric insert component for a planar electrical heating apparatus, methods for assembling a planar electrical heating apparatus and methods for manufacturing a planar electrical heating apparatus.

According the invention there is provided a planar electrical heating apparatus according to claim <NUM>.

In preferred embodiments there is provided a heating apparatus that includes an outer shell with an upper shell layer joined to a lower shell layer and defining an internal cavity or chamber therebetween. Preferably, an electric heating element is positionable within the internal cavity, between the upper layer and lower layer, the heating element with at least one heating conductor, at least two non-heating conductors, and with or without a flexible or substantially rigid substrate. Preferably, an electric insert is positionable within the internal cavity between one of the shell layers and the heating element, the electric insert configured in an embodiment of the present invention to underlie at least a portion of the outer shell, the insert including a connector having a first connector end portion connectable to an electrical power supply and a second connector end portion connectable to the non-heating conductors. Preferably, the upper and lower layers may be permanently or detachably attached and sealed to each other or to the upper and lower faces of the heating element at its axial side edges along a majority of the perimeter of the apparatus. Preferably, the perimeter of the apparatus also includes an unsealed portion defining a receptacle within which the heating element and/or insert are receivable.

According to a second aspect there is provided an outer shell component for a planar electrical heating apparatus enclosing a heating element having an electrically resistive heating conductor operable using AC or DC power comprising:.

According to a third aspect, there is provided an electric insert for a planar electrical heating apparatus with an outer shell and an internal cavity, the internal cavity including an upper inner cavity surface and a lower inner cavity surface, the electric insert receivable and positionable within the internal cavity, the outer shell including an upper shell layer and a lower shell layer defining the internal cavity, wherein the upper shell layer and the lower shell layer are attachable using a first bond along the periphery and attachable using a second bond between the upper inner cavity surface and the lower inner cavity surface, the first bond at least as strong as the second bond, the electric insert comprising:.

The drawings, described below, are provided for purposes of illustration, and not of limitation, of the aspects and features of various examples of embodiments described herein. For simplicity and clarity of illustration, elements shown in the drawings have not necessarily been drawn to scale. The dimensions of some of the elements may be exaggerated relative to other elements for clarity. It will be appreciated that for simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the drawings to indicate corresponding or analogous elements or steps.

For a better understanding of the described embodiments and to show more clearly how they may be carried into effect, reference will now be made, by way of example, to the accompanying drawings.

Furthermore, it will be appreciated that for simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein may be practiced without these specific details. In other instances, well known methods, procedures and components have not been described in detail so as not to obscure the embodiments described herein. Also, the description is not to be considered as limiting the scope of the embodiments described herein.

Advances in materials science and nanotechnology are leading to new forms of electric heating elements. Large surface area heating elements are being manufactured with thin profiles or as free-form objects and using materials that may be flexible or substantially rigid and intended to replace electric heat trace cable and applications thereof. Examples of heating elements being developed include heating elements that use materials such as conductive inks, coatings, elastomerics, concretes, and even woven/non-woven fabrics. These heating elements may be manufactured in large-scale, for instance in rolls and/or sheets. For example, electrically resistive carbon nanotube (CNT) ink materials may be used to print large-surface area resisitive heating films that can be manufactured roll-to-roll. In other example, high electrical conductivity copper or silver inks materials may be used to print inductive heating films that can be manufactured in sheets.

These electric heating elements may provide increased versatility and allow for use in different applications. For example, these electric heating elements may be integrated into heating assemblies in industries such as construction, transportation, and consumer appliances. However, these electric heating assemblies tend to be highly customized to the particular implementation. As a result, specific heating assemblies are constantly designed based on the installation location and application.

For example, the components used in heating assemblies may be specifically selected based on their intended use and requirements. In some cases, the heating element may not meet the flammability properties based on the requirements of the intended use. In some cases, additional components such as thermal layers, electrical insulation layers, and conductive coverings may be selected depending on the requirements and what is readily available. Generally, these assemblies by not be easily repairable, and may be unalterable given the specialized nature of their construction. For example, in room heating applications a conductive covering is typically assembled separately and may result in nuisance tripping after construction. The electric circuitry and wiring associated with the assembly may also be imbedded in the assembly at the manufacturing stage resulting in circuitry that cannot be accessed or repaired such as when used in applications within concrete. The electrical circuitry and wiring may be attached to the exterior of the assembly resulting in bulky connections which can introduce dangers such as tripping when used in applications such as connecting overground mats together for driveway heating.

In a preferred embodiment of the present invention, there is provided planar electrical heating systems, apparatuses and assemblies for customized application criteria containing a plurality of layers.

In a preferred embodiment of the present invention, there is provided planar electrical heating systems, assemblies and apparatuses for connecting low profile installations containing electric insert circuitry.

Embodiments described herein generally relate to electrical heating systems, assemblies, apparatuses and components therefor. Embodiments described herein may also provide methods for manufacturing electrical heating systems, assemblies and apparatuses (or components) and methods for assembling them. Some of the embodiments described herein may address one or more of the above-noted problems associated with existing applications, systems, assemblies of electrical heating elements. Embodiments described herein may also be used to provide electrical heating apparatuses for various industries and applications for fixed-location installations or as portable appliances. Some applications include over/under floor coverings, over/under pavements, over/under roofing, in-ceilings, around pipes and vessels, in/over/around equipment or containers, in/over/under transportation vehicles or trailers, and for personal heating such as mats, blankets and clothing.

Embodiments described herein may facilitate modular assembly of electrical heating apparatuses using planar electrical heating elements. An outer shell may be provided that defines an internal cavity within which the connections of a heating element may be positioned. In general, the perimeter of the outer shell is permanently or detachably sealed with the exception of an unsealed receiving portion that is shaped to receive an electrical insert and make connections. The outer shell may be provided in various shapes depending on the particular implementation. For example, the outer shell may be provided as triangular shell, rectangular shell, oval shell etc. depending on the characteristics of the installation.

In an embodiment of the present invention, the shell element may generally extend in an axial dimension. For instance, the shell may have a substantially rectangular geometry and extend in a lengthwise direction. This may facilitate large-scale manufacturing and distribution on rolls. The axial side edges of the shell can be permanently or detachably sealed to define the internal cavity.

For simplicity and ease of exposition, the example embodiments described herein may be described in reference to a substantially rectangular heating apparatus having a rectangular outer shell. However, a skilled reader will appreciate that the shape of the example heating apparatuses described herein are not to be limited to rectangular, and other shapes may also be used. For simplicity and ease of exposition, the example embodiments described herein may also be described in reference to a flexible electric resistance heat trace element, which may be manufactured as a roll. A desired dimension of series or parallel heating element may be positioned and secured within the inner cavity to provide a covered or protected heating element. As described herein below, the circuit topology of the heating element may be selected to allow the heating element to accommodate the shape of the shell while still ensuring that the heating element traces retain electrical continuity. In an embodiment of the present invention, the covered heating element (i.e. the shell and heating element) may be manufactured together as a roll.

The heating element may be a thick-film or thin-film electric heat trace element, which may be manufactured as a roll. A desired dimension of heating element may be positioned and secured within the inner cavity to provide a covered or protected heating element. As described herein below, the circuit topology of the heating element may be selected to allow the heating element to accommodate the shape of the outer shell while still ensuring that the heating element traces retain electrical continuity. In an embodiment of the present invention, the covered heating element (i.e. the outer shell and heating element) may be manufactured together as a roll.

An electric insert may also be provided. For simplicity and ease of exposition, the example embodiments described herein may also be described in reference to a planar insert, which may include insert circuitry that is electrically connectable to the heating element. The insert circuitry may include power and/or control circuits. In an embodiment of the present invention, the flexible insert may also include one or more external connectors. The external connectors may be electrically connectable to a power source and/or an external controller.

The planar electric insert may be positioned within the internal cavity with the insert circuitry electrically connected to the heating element. For example, the insert may be positioned between an inner layer of the shell and the heating element. One or more connectors may extend through the shell or between the lower shell layer and the upper shell layer to provide a connection to other heating apparatuses, an external power source and/or controller.

The use of a planar electric insert may enable the heating apparatus to be customized during assembly on site for a particular installation. A length of covered heating element may be selected on-site during an installation, and the insert can be easily placed into or inserted into the cavity. This may facilitate installation and provide a planar electrical heating apparatus with a less bulky profile and avoid loose external wires. As well, the outer shell may protect electric components of the insert from environmental conditions such as direct water contact, moisture and humidity.

In preferred embodiments, the electric insert may be removable from the heating apparatus. This may facilitate repairing or replacing components in the heating apparatus, even after installation.

Referring now to <FIG>, shown therein is an example embodiment of an electrical heating apparatus <NUM>. It will be understood that different embodiments of the present invention are shown in <FIG>. Similar elements of these embodiments are identified with the same reference numerals. As shown in the example of <FIG>, the heating apparatus <NUM> includes an outer shell <NUM>, a heating element <NUM>, and an insert <NUM>. <FIG>, <FIG> and <FIG> show partially exploded perspective views of the heating apparatus <NUM>. <FIG>, <FIG>, and <FIG> show cross-sectional views of the heating apparatus <NUM>.

Embodiments of heating apparatus <NUM> may provide either a fixed or portable electrical heating apparatus. For example, thin and flexible materials may be used to manufacture and assemble heating apparatus <NUM> allowing for easy installation in fixed locations or as portable appliances.

As well, embodiments of heating apparatus <NUM> may be assembled in a modular manner. This may allow different configurations of the various components of heating apparatus <NUM> (e.g. the shell <NUM>, heating element <NUM>, conductive covering layer <NUM>, thermal/dielectric layer <NUM>/<NUM>, insert <NUM> and couplings <NUM>) to be manufactured, assembled, and even interchanged depending on the particular implementation, installation, etc..

The heating element <NUM> may include a plurality of resistive or inductive heating conductors without a substrate or with, or on, a substrate. The heating element <NUM> may be manufactured using various materials such as conductive inks, coatings, elastomerics, concretes, and even woven/non-woven fabrics. For example, in preferred embodiments a conductive ink or coating may be deposited on a surface of a substrate in a defined pattern to provide the resistive or inductive heating conductors of the heating element <NUM>. In other embodiments, conductive fabrics may even be integrated into the substrate material (e.g. woven into the substrate) to provide resistive heating elements.

The resistive heating conductors of the heating element <NUM> may be manufactured of materials that are self-regulating with variable resistance in relation to temperature, or regulated with fixed resistance in relation to temperature.

The resistive or inductive heating conductors of the heating element <NUM> may be arranged into defined circuit patterns to facilitate shaping of the heating element <NUM>. Referred example resistive circuit topologies that may facilitate shaping the heating element <NUM> are shown in <FIG>.

The heating element <NUM> can have a generally planar shape. That is, the heating conductors may be substantially co-planar with the substrate, or have a minimal elevation over the surface of the substrate. For example, a woven electrically resistive mesh or scrim may be upwards of <NUM> (<NUM> mil) in height. This can provide a relatively compact resistive heating element <NUM>. In other examples, a cast electrically resistive concrete heating element may provide a plurality of generally planar surfaces of different surface textures, dimensions and orientations. This may also provide an opportunity for a planar electrical heating apparatus consistent with the embodiments described herein.

In an embodiment of the present invention, the heating element <NUM> may be flexible. For instance, the substrate and resistive or inductive heating conductors may be manufactured from flexible materials. Accordingly, the heating element <NUM> may flex to facilitate manufacturing and/or non-planar installations.

Alternatively, the heating element <NUM> may be substantially rigid. This may help ensure that the heating element <NUM> does not flex or become dislodged after installation. This may be particularly useful in the case of conductive woven/non-woven fabric heating elements.

In an embodiment of the present invention, the heating element <NUM> may be flame retardant. For instance, the substrate may be manufactured from materials with additives that extinguish and minimize the spread of a flame. Accordingly, the heating element <NUM> may facilitate the flammability requirements for certain installations well known in the art.

In an embodiment of the present invention, the heating element <NUM> may not be flame retardant. For instance, the substrate of the heating element may be manufactured from materials that spread a flame and result in ignited drippings. Accordingly, the heating element <NUM> itself may not meet the above noted flammability requirements but the outer shell <NUM> may provide such flammability requirements so as to facilitate or meet the flammability requirements of the entire heating apparatus <NUM>, particularly for certain installations (e.g. in room heating constructions, including but not limited to, under floor installations).

In various embodiments, the heating element <NUM> can be electrically powered by AC or DC currents. Current can pass through the resistive or inductive heating conductors which dissipates the electrical energy as heat or magnetic flux. This provides the heating function of the heating element <NUM>. The heating element <NUM> can also include non-heating conductors, or heating element leads, that are connectable to power and/or control circuits, which can in turn be connected to a power source and/or external control circuitry. An example embodiment of a heating element <NUM> that may be used for the heating element <NUM> is described in further detail below with reference to <FIG>.

The outer shell <NUM> can be used to enclose the heating element <NUM>. In preferred embodiments, the shell <NUM> may provide a covering enclosing the heating element <NUM> that may protect the heating element <NUM> from damage that may be caused by environmental conditions. In preferred embodiments, the outer shell <NUM> may also include electrical protection layers, such as conductive covering layers <NUM>, to ground the heating element <NUM>.

In general, the outer shell <NUM> includes an upper layer <NUM> and a lower layer <NUM>. The inner surface <NUM> of the upper layer <NUM> faces the inner surface <NUM> of the lower layer <NUM>. The upper layer <NUM> and lower layer <NUM> can be joined along the majority of the perimeter of outer shell <NUM> to define an internal cavity. Alternatively, the upper layer <NUM> and lower layer <NUM> can be joined along the majority of the perimeter of heating element <NUM> to define an internal cavity containing the connections for the heating element. The upper layer <NUM> and lower layer <NUM> can be left unsealed (or detachably attached) for a portion of the perimeter to define an insert receiving space.

For example, where the outer shell <NUM> is rectangular, the upper layer <NUM> and lower layer <NUM> can be joined at their axial side edges <NUM> and <NUM> to define an internal cavity of the outer shell <NUM> as shown in <FIG> and <FIG>. The heating element <NUM> can be positioned in the internal cavity of the outer shell <NUM>.

Alternatively, the upper layer <NUM> and lower layer <NUM> can be joined at the axial side edges <NUM> and <NUM> of the heating element to define an internal cavity of the outer shell <NUM> as shown in <FIG>. The heating element <NUM> connections can be positioned in the internal cavity of the outer shell <NUM>.

In the example shown in <FIG>, <FIG> and <FIG>, the outer shell <NUM> may also include a central region <NUM> between the axial side edges <NUM> and <NUM>. The central region <NUM> can define the insert receiving space. In an embodiment of the present invention, the central region <NUM> may not have any bonding or adhesive materials. This may allow the internal cavity to be easily opened to allow the heating element <NUM>, insert <NUM> and/or other elements to be positioned in the internal cavity.

Alternatively, the axial side edges <NUM> and <NUM> and/or central region <NUM> may include detachable bonding materials, such as a weak adhesive or hook and loop fasteners. This may ensure that the internal cavity of the outer shell <NUM> remains closed prior to assembly of the heating apparatus <NUM>, while allowing the internal cavity to be opened for positioning of the heating element <NUM> and/or insert <NUM>. Having a detachable bonding material along the axial side edges <NUM> and <NUM> or within the central region or internal cavity <NUM> may also assist in securing the heating element <NUM> and/or insert <NUM> in position within the cavity. It will be understood that the central region or internal cavity may represent space provided in the devices of the present embodiments to receive or secure the heating element <NUM>, insert <NUM>, etc. as well as prevent the heating element <NUM> and/or insert <NUM> from being displaced during use.

Preferred embodiments of the heating apparatus <NUM> may be used for indoor or outdoor applications. The heating apparatus <NUM> can have a generally planar profile, which may facilitate applications such as floor heating, wall heating, and snow melting/removal. Securing the heating element <NUM> within the internal cavity, e.g. using a detachable bonding material, may ensure that the heating element <NUM> is not displaced or flexed when people, animals or vehicles move across the outer surface of the shell <NUM>.

The outer shell <NUM> can also be made of flexible materials. This may facilitate assembly by allowing the outer shell <NUM> to be easily opened to insert the heating element <NUM> and/or insert <NUM>. This may also facilitate using the heating apparatus <NUM> on non-planar surfaces, such as applications where the apparatus is wrapped around objects or persons such as equipment blankets, clothing or sleeping bags.

The outer shell <NUM> can also be made of substantially rigid materials. This may facilitate assembly by allowing the outer shell <NUM> to be constructed with an defined opening to insert the heating element and/or insert <NUM>. This may also facilitate using the heating apparatus <NUM> on substantially planar surfaces, such as applications where the apparatus is permanently installed on, or part of, a surface such as pavement.

An example embodiment of an outer shell component <NUM> that may be used as an outer shell <NUM> is described in further detail below with reference to <FIG>.

In preferred embodiments, an electric insert <NUM> may be used having an electric circuit that is electrically connectable to the heating element <NUM> to a source power and/or control.

The electric insert <NUM> may also be manufactured of flexible or substantially rigid materials. This may facilitate positioning the insert <NUM> within the internal cavity of the shell <NUM> during assembly.

The use of an electric insert <NUM> may enable an electrical heating apparatus <NUM> to be customized during assembly for a particular installation. A length of covered heating element <NUM> may be selected on-site during an installation, and the electric insert <NUM> and couplings <NUM> can be easily placed into the cavity <NUM>. This may facilitate installation and provide a planar heating apparatus <NUM> with a less bulky profile and avoid loose external wires as couplings <NUM> with a relatively low-profile construction not exceeding the height of the heating apparatus <NUM>. As well, the upper shell <NUM> and lower shell <NUM> may protect electronic components of the inserts <NUM> and electric couplings <NUM> from environmental conditions such as direct water contact, moisture and humidity. The electric insert <NUM> may be positioned within the internal cavity <NUM> with the insert circuitry electrically connected to the heating element.

In various embodiments, as shown in <FIG>, the insert <NUM> can be positioned within the internal cavity <NUM> between the upper layer <NUM> (or lower layer <NUM>) of the shell <NUM> and the heating element <NUM> with insert circuitry electrically connected to the heating element <NUM>.

In preferred embodiments, an isolation layer <NUM> with thermal and electrical insulation properties may be positioned between the heating element <NUM> and the insert <NUM>. This may prevent overheating of the insert from the heat generated by the heating element and provide further electrical protection while securing the insert <NUM> to the heating element <NUM>.

In various embodiments, as shown in <FIG>, the electric insert <NUM> may be placed co-planar with the heating element <NUM> within the internal cavity <NUM> and between the upper layer <NUM> (or lower layer <NUM>) of the shell <NUM> with insert circuitry electrically connected to the heating element <NUM>. The electric insert may have a relatively low-profile construction not exceeding the height of the electrical heating apparatus <NUM>.

In some embodiments, one or more electric inserts <NUM> may extend in a continuous direction perpendicular to the axial edges of the heating element <NUM> to provide coupling <NUM> to other heating elements <NUM> (and/or, as noted above other apparatuses <NUM>), and external power source and/or controller. For example, in <FIG> shows an insert <NUM> providing an electrically continuous power busbar system (e.g. continuously extending perpendicular beyond edges <NUM> and/or <NUM>) to enable connecting multiple heating elements <NUM> to each other and/or to other heating apparatuses <NUM>.

In preferred embodiments, the electric insert may be removable from the heating apparatus. This may facilitate repairing or replacing components in the heating apparatus, even after assembly and installation.

The insert <NUM> can include a plurality of connector end portions and terminal coupling components <NUM>. The coupling components <NUM> can be used to electrically connect the electric circuit on the insert <NUM> with the leads of the heating element <NUM>. For example, the coupling components <NUM> may be provided as foil terminal butt splice connectors, or conductive foils with mechanical fasteners. The coupling components may then be mechanically crimped, riveted, bolted, adhered or otherwise attached to both the insert circuitry and the non-heating conductors, or leads, of the heating element <NUM> to electrically couple the heating element to the insert circuitry.

In preferred embodiments, after electrically coupling the heating element to insert circuitry, the maximum voltage drop between the non-heating leads of the heating element and the electric circuit is less than <NUM>% of the rated voltage when the full load current of the heating element is applied at the rated temperature.

In preferred embodiments, the coupling components <NUM> may also include a grounding component. The grounding component can couple the insert <NUM> to a conductive covering <NUM> or a grounding strap <NUM> provided by a grounding layer of the outer shell <NUM>.

The insert circuitry may include power and/or control circuits (not shown). In preferred embodiments, a microcontroller may be included in the insert circuitry to control operation of the heating element <NUM>.

Alternatively, a microcontroller may be omitted. In such embodiments, operation of the heating element <NUM> may be controlled by an external controller. Alternatively, the heating element <NUM> may be configured to be always on when connected to a power source. Operation of the heating element <NUM> may then be controlled by connecting/disconnecting the power source.

The insert <NUM> can also include one or more junction boxes, cable glands, molded coverings, or external coupling assembly <NUM>. The junction box, cable gland, molded covering, or coupling assembly <NUM> may be used to couple the heating apparatus <NUM> to a power source and/or external control circuitry. When the insert <NUM> is positioned in the cavity of the shell <NUM>, the insert <NUM> and junction box, cable gland, molded covering, or coupling assembly may extend through the upper layer <NUM> or lower layer <NUM> to facilitate a connection to an external power source and/or controller. For example, the upper layer <NUM> and/or lower layer <NUM> may include one or more cut-out portions or apertures <NUM> to provide a connection to other heating apparatuses, an external power source and/or controller. The cut-out portions <NUM> may be shaped to accommodate the insert <NUM>, junction box, cable gland, molded covering, or coupling assembly <NUM> on the insert <NUM>.

After the insert <NUM> is positioned in the internal cavity <NUM> of the shell <NUM>, the edges of the cut-out portions <NUM> may be sealed to the insert <NUM>. This may prevent direct water contact, moisture or other environmental debris from contacting the heating element <NUM> or the circuitry on insert <NUM>.

Preferred embodiments of inserts and couplings <NUM> that may be used with the heating element <NUM> as part of an electrical heating apparatus <NUM> is described in further detail below with reference to <FIG>.

In preferred embodiments, one or more cut-outs or apertures <NUM> may extend through the upper layer <NUM> and lower layer <NUM> at the axial side edges <NUM> and/or <NUM> to provide a means of mounting an external coupling assembly <NUM> such as a gasket and side entry cable gland for strain relief. For example, an IP67 rated Index Marine SE6 side entry gland and gasket may be used for strain relief of cables (not shown) to an external power source and/or controller may be mounted above an aperture <NUM>, or through an aperture <NUM>. In other examples, the cables (not shown) of a coupling assembly may be secured to the axial side edges <NUM> and/or <NUM> through two cut-out holes <NUM> using a tie-strap passed through and around the cable to provide strain relief, or further provide strain relief. Alternatively, an external coupling may be mounted through cut-out holes <NUM> using fire retardant nylon bolt with nut.

In the example of <FIG>, the apparatus <NUM> may also include sealing components <NUM>/<NUM> comprised of, for example, and not limited to, fusing adhesive tapes or other sacrificial detachable adhesive to allow easier access. The sealing components <NUM>/<NUM> may be used to seal the insert <NUM>, couplings <NUM>, and ends of the heating apparatus <NUM> after the heating element <NUM> and insert <NUM> have been positioned within the shell <NUM> during manufacture or on-site assembly.

In a preferred embodiment, the sealing components <NUM>/<NUM> may be manufactured of materials that are flame retardant to prevent the spread of a flame. An example thereof is <NUM>™ Scotch™ <NUM> Cable Jacket Repair Tape manufactured of butyl rubber and mastic with self-fusing properties.

In preferred embodiments, such as shown in <FIG>, where the heating apparatus includes a grounding layer, the shell layers <NUM>/<NUM> and a conductive covering <NUM> may be extended in the axial direction beyond the edge of the heating element so as to become integrated over or folded around the sealing end portion components <NUM> of inserts <NUM> and couplings <NUM> before sealing the ends of the heating apparatus with sealing component <NUM>. This facilitates electrical shock hazard protection around inserts <NUM> and couplings <NUM> using the same conductive covering <NUM> electrically connected to the ground plane.

In preferred embodiments, where the heating apparatus includes a grounding layer and heating element co-planar with the insert <NUM> (see for example <FIG>), a shell layer <NUM>/<NUM> and conductive covering <NUM> may be integrated over or folded around the sealing end portion components <NUM> of insert <NUM> and couplings <NUM> onto the other shell layer <NUM>/<NUM> and optionally excluding sealing end portion of the apparatus <NUM>.

In preferred embodiments, the sealing end portion <NUM> may be mechanically secured to the outer shell layer <NUM>, or through the outer shell layer <NUM>, to provide permanent sealing of the apparatus. For example, shell layers <NUM>/<NUM> may be extended axially beyond the edge of the heating element <NUM> and rivets or gromets may be fastened through shell layers <NUM>/<NUM> and the sealing ends <NUM>.

In preferred embodiments, the ends of the shell <NUM> may be sealed in the same manner as the axially extending side edges.

Referring now to <FIG>, shown therein is a cross-sectional view of a shell <NUM> that includes a plurality of shell layers. Shell <NUM> is an example of an outer shell that may be used in embodiments of the heating apparatus <NUM>.

In the example shown in <FIG>, the shell <NUM> includes a plurality of upper shell layers (<NUM>, <NUM>, <NUM>, <NUM>) and a plurality of lower shell layers (<NUM>, <NUM>, <NUM>, <NUM>). The upper shell layers and lower shell layers face one another and define an internal cavity <NUM> of the shell <NUM> therebetween.

The shell <NUM> generally includes a first upper layer (or upper covering layer) <NUM> and a first lower layer (or lower covering layer) <NUM>. The first upper layer <NUM> and first lower layer <NUM> may be protective layers used to shelter the electrical elements in the heating apparatus from the environment. This may protect these electrical elements from damage due to environmental dangers such as direct water contact, moisture, contaminants and electrical leakage currents.

In the shell <NUM>, the first upper layer <NUM> and first lower layer <NUM> are insulating layers that define an outer insulating layer of the shell <NUM>. The insulating layers <NUM>/<NUM> can enclose electric heating elements, and other electrical components (e.g. control circuitry), and electrically isolate those components from the external environment. This may protect these electrical components, as well as the surrounding environment, from damage or shock hazards that may occur due to leakage current through the shell.

In preferred embodiments, the insulating layers <NUM>/<NUM> may also have additional protective properties. For example, the insulating layers <NUM>/<NUM> may be manufactured of materials having mechanical and/or chemically resistive properties. Mechanical resistive properties may generally refer to material properties (such as compressibility) that may be reduce the potential damage caused by impacts. Chemical resistive properties may provide resistance to damage caused by basic or acidic materials that come into contact with the outer surface <NUM> of the shell <NUM>.

In preferred embodiments, the insulating layers <NUM>/<NUM> may provide other physical properties such as higher flame retardance where the heating element does not meet flammability requirements of a particular construction.

In some cases, the insulating layers <NUM>/<NUM> may provide other thermal properties such as high or low thermal conductivity, high or low thermal capacitance, high or low surface emissivity, high or low transparency to thermal radiation. For example, as shown in, for example, <FIG>, insulating layer <NUM> may be a flame retardant aerogel blanket layer having <NUM> W/mK thermal conductivity at <NUM> degrees centigrade laminated to an aluminized radiant barrier film layer having <NUM> surface emissivity.

In preferred embodiments, the insulating layers <NUM>/<NUM> may be manufactured of fluoropolymer materials sufficiently thick (e.g. upwards of <NUM>, i.e. <NUM> mil. ) to provide some of the above mentioned properties as an electric cable jacket for a planar heating apparatus. Examples of fluoropolymer jacket materials provided as the insulating layers <NUM>/<NUM> include perfluoroalkoxy (PFA), polytetrafluoroethylene (PTFE) or fluorinated ethylene propylene (FEP).

In preferred embodiments, the upper shell <NUM> may consist of a second functional layer <NUM> that may be detachably attached to an upper shell <NUM>. For example, a high-traction surface tread such as <NUM>™ Safety-Walk™ <NUM> Series tape may be provided to mitigate slip-and-fall incidents where the electrical heating apparatus <NUM> is used over pavement surfaces to melt snow and de-ice. This layer may be removed or replaced to repair the layer after wear. In other examples, an anti-fracture membrane may be provided to allow for embedding within thin-set mortar or concrete.

In preferred embodiments, the lower layer <NUM> may be consist of a second functional layer <NUM> that may be detachably attached to a lower shell <NUM>. For example, the second functional layer <NUM> may be a flame retardant thermal insulation layer. In other examples, a flame retardant EPDM or vulcanized silicone rubber may be used to further protect the electrical heating apparatus <NUM> from penetration of objects on the installation surface, and provide additional weight that prevents movement when installed over pavement surfaces to melt snow and de-ice.

In preferred embodiments, the insulating layers <NUM>/<NUM> or secondary functional layers <NUM>/<NUM> may provide electric functionality, such as temperature sensing, force sensing, lighting, power generation, or electrical storage. For example, an printed photovoltaic circuit <NUM> may be laminated onto the upper shell layer <NUM> and a planar rechargeable battery <NUM> may be secured to the lower shell layer <NUM> to provide a heating apparatus that is energy sustainable. In other examples, a printed electroluminescent circuit may be laminated to a piezoelectric generator together as a functional layer <NUM> that may be laminated to the upper shell layer <NUM> to provide a heating apparatus that stores kinetic energy from pedestrian traffic for floor lighting.

In preferred embodiments, the upper layer <NUM> and lower layer <NUM> may be manufactured of different materials and/or may have different thickness. The first upper layer <NUM> may be manufactured to provide greater heat transfer than the first lower layer <NUM>. For example, the second upper layer <NUM> may be manufactured of a <NUM> (<NUM> mil) thick section of <NUM>™ Safety Walk™ <NUM> series while the second lower layers <NUM> can be manufactured of a <NUM> (<NUM> mil) thick EPDM rubber.

Additionally or alternatively, the upper layers <NUM>/<NUM> may be manufactured of materials that provide additional resistance to impact damage where the upper layers <NUM>/<NUM> are exposed while the lower layers <NUM>/<NUM> rest on a surface such as a driveway.

The outer peripheral regions of the first upper layer <NUM> and first lower layer <NUM> may be joined together to define a perimeter of the shell <NUM>. For example, in the case of a rectangular shell <NUM>, the axial side regions of the first upper layer <NUM> and first lower layer <NUM> can be joined together. In general, the bond between the first upper layer <NUM> and first lower layer <NUM> may permanently secure the perimeter of the first upper layer <NUM> and first lower layer <NUM> to form the outer layer of the shell <NUM>. The bond between the perimeter of the first upper layer <NUM> and first lower layer <NUM> may be a watertight (or substantially waterproof) seal, to prevent water from seeping into the internal cavity <NUM> and potentially damaging the electrical components enclosed therein.

As shown in <FIG> and <FIG>, the first upper layer <NUM> and first lower layer <NUM> can be adhered to one another by an adhesive layer <NUM>. For example, a <NUM>™ Double Coated Tape with <NUM>™ Silicone Adhesive or <NUM>™ VHB™ Tapes may be used as the adhesive layer <NUM>.

As shown in <FIG> the second upper layer <NUM> and first lower layer <NUM> can be adhered to one another by an adhesive layer <NUM>. For example, a <NUM>™ Double Coated Tape with <NUM>™ Silicone Adhesive or <NUM>™ VHB™ Tapes may be used as the adhesive layer <NUM>.

As shown in <FIG>, the shell <NUM> can also include a grounding layer formed by upper conductive covering layer <NUM> and lower conductive layer <NUM>. The conductive covering layers <NUM>/<NUM> may operate as a ground plane used to couple the heating element to ground. The conductive covering layers <NUM>/<NUM> may be connected to ground for residual-current detection using a ground fault current interrupter (GFCI) or ground fault equipment protector (GFEP) device.

As shown in <FIG>, the shell <NUM> can also include a single conductive covering layer <NUM> for protection from electrical shock hazards on the side of heating apparatus <NUM> most likely to experience physical damage.

In general, the conductive layers <NUM>/<NUM> may be conductive substantially throughout their entire surface area to ensure that the heating element can be grounded at any location. For example, the conductive layers <NUM>/<NUM> may provide electrical continuity to within about <NUM> - <NUM> Ohms across the longest length of the conductive layers <NUM>/<NUM>. In some examples, the conductive covering <NUM>/<NUM> may provide a DC resistance per unit length equal to or less than that of the lowest resistance heating conductor per unit length.

The conductive covering <NUM>/<NUM> may carry a minimum current per cross sectional area (e.g. of foil or wire) at least equal or less than the current carrying capacity of the non-heating conductors of the heating element per cross sectional area at the temperature rating of the heating apparatus.

In preferred embodiments, the conductive layers <NUM>/<NUM> may be manufactured using various electrically conductive materials such as inks, foils, wire braids, meshes, and coatings that cover substantially the entire planar area of the heating element or a defined pattern with open area as illustrated in <FIG>. As with the protective layers <NUM>/<NUM>, in preferred embodiments the upper conductive layer <NUM> may provide greater heat transfer than the lower conductive layer <NUM>. For example, the upper conductive layer <NUM> may be manufactured using a thinner section of aluminum foil as compared to the lower conductive layer <NUM>.

As shown in <FIG>, providing a conductive layers <NUM>/<NUM> with a defined pattern having a maximum <NUM>% open area over the heating element may reduce capacitive reactance and leakage conductance between the conductive layers <NUM>/<NUM> and the heating element.

In preferred embodiments, providing a conductive layers <NUM>/<NUM> with a defined pattern having a maximum <NUM>% open area over the heating element may also increase transparency to thermal radiation and reduce the effect of EMI shielding. This may be especially useful in room heating applications, where maximum thermal radiation is desirable and EMI shielding is generally undesirable.

In some embodiments, a defined pattern of a conductive layer <NUM>/<NUM> may provide a maximum circular hole diameter or square hole dimension <NUM> up to <NUM> (<NUM> mil. ) in the central region of the heating element. This may facilitate a ground fault condition when sharp objects wider than <NUM> penetrate through the conductive covering layer <NUM>/<NUM> and into the heating element.

In preferred embodiments, the defined pattern may not extend beyond the regions containing the non-heating conductors <NUM> which may provide protection from objects penetrating through the conductive covering layer <NUM>/<NUM> and into the low-resistance non-heating conductors of the heating element.

In preferred embodiments, the conductive layers <NUM>/<NUM> may be manufactured of low or high emissivity materials providing thermal radiation outwards toward a preferred upper layer <NUM> or lower shell layer <NUM>. For example, an aluminum <NUM> series alloy foil may be chosen with a mill finish instead of a polished finish to improve emissivity of the shell layer <NUM>. In other embodiments, a surface texture between <NUM> - <NUM> microns is desirable to improve the emissivity of far infrared radiation (IR).

The conductive layer <NUM> and <NUM> may also be attached to one another to form a continuous inner shell layer, as shown in <FIG>. The periphery (e.g. the side edges) of the conductive layers <NUM> and <NUM> may be attached using a conductive coupling to provide a continuous conductive layer. For example, a conductive adhesive <NUM> (e.g. <NUM>™ Conductive Adhesive Transfer Tape or <NUM>™ Conductive Aluminum Foil Tape) may be used to attach the conductive layers <NUM> and <NUM> to one another.

The conductive layer <NUM>/<NUM> can be secured to the upper and lower protective layers <NUM> and <NUM> respectively. In general, the conductive layers <NUM>/<NUM> may be fixed to the upper and lower protective layers <NUM> and <NUM> to prevent relative movement therebetween after manufacturing. For example, the conductive layers <NUM>/<NUM> may be adhered to the upper and lower protective layers <NUM> and <NUM>, using an adhesive layer <NUM> that extends substantially across the outer surface of the conductive layers <NUM>/<NUM>.

As part of an outer shell layer construction for grounding, shown in <FIG>, the inner surface of the conductive covering layer <NUM>/<NUM> may also be permanently or detachably attached to a dielectric layer <NUM> having an attachment region <NUM>. The dielectric layer <NUM> may electrically insulate the heating element <NUM> from the conductive covering layer <NUM>/<NUM> to further reduce capacitive reactance and ground leakage conductance to conductive covering layer <NUM>/<NUM>.

In embodiments of the present invention, the dielectric layer materials may be manufactured of materials with substantially low dielectric constant (e.g. <NUM> - <NUM>) over the operating frequency of the heating apparatus <NUM> to mitigate leakage conductance over greater surface areas or with longer lengths.

In preferred embodiments, the dielectric layer <NUM> may be manufactured of fluoropolymer materials sufficiently thick (e.g. up to <NUM>, i.e. <NUM> mil) to provide some of the above mentioned properties as an electric cable dielectric for a planar heating apparatus. For example, fluoropolymer materials provided as the dielectric layer <NUM> include nanoporous or microporous polytetrafluoroethylene (PTFE) or expanded PTFE (ePFTE) such as Porex® substrate films, <NUM>™ Dyneon™ membranes, Saint Gobain ZITEX® G membranes, or closed-cell foams fabricated with Teflon™ FFR.

In preferred embodiments, the insulating layer <NUM>/<NUM> and dielectric layer <NUM> may provide dimensional stability where penetration of a conductive object may occur through the shell <NUM>, into the conductive covering <NUM>/<NUM> and dielectric layer <NUM>. In preferred embodiments, dimensional stability may ensure the conductive covering does not shear in order to provide electrical continuity between a conductive object and the ground sheath. For example, dimensional stability in the shell layer <NUM> provides a reliable connection to the conductive covering where insulation piercing connectors are used to connect to the conductive covering <NUM>/<NUM> through the shell layer <NUM>/<NUM> such as Tyco TERMI-FOIL or CommScope Undercarpet Cabling Splice and Tap Clips.

In preferred embodiments, the outer shell construction including the insulating layers <NUM>/<NUM>, conductive coverings <NUM>/<NUM>, and dielectric layers <NUM>, may provide protection of a planar heating apparatus from further catching fire in the event of an electrical short or ground fault. For example, the outer shell construction with grounding may provide higher flame resistance than the heater element to prevent the spread of flames and ignited material drippings resulting from internal combustion of the heating element or external exposure of the heating apparatus to a flame.

In preferred embodiments, the shell layer <NUM> may be water permeable including the insulating layers <NUM>/<NUM>, conductive coverings <NUM>/<NUM>, and dielectric <NUM> layers. For example, the heating element may be perforated where installing within soil or under concrete such that water may permeate through the shell <NUM>.

In preferred embodiments, the outer surface of a conductive covering layer <NUM>/<NUM> may be in direct contact with a grounding strap <NUM> for a preferred direction of connection of grounding strap <NUM> exterior to the apparatus. In other embodiments, the inner surface of a conductive covering layer <NUM>/<NUM> may be in direct contact with grounding strap <NUM> for a preferred direction of connection of grounding strap <NUM> interior to the apparatus.

A grounding strap <NUM> may be electrically continuous with the conductive covering layer <NUM>/<NUM> and extend along the axial length. The grounding strap <NUM> may provide a low-resistance path for electrical leakage currents to travel from any point on the surface of the conductive covering layer <NUM>/<NUM> to ground or earth potential.

In preferred embodiments, the maximum voltage drop between conductive covering <NUM>/<NUM> and grounding strap <NUM> may be less than <NUM>% of the rated voltage when the full load current of the heating element is applied at the rated temperature.

In embodiments using conductive layers <NUM>/<NUM>, the conductive layers <NUM>/<NUM> or any dielectric layers <NUM> may define an inner or interior surface <NUM> of the shell <NUM>. In general, the inner surface <NUM> of the shell <NUM> may refer to the surface of the shell <NUM> facing the internal cavity <NUM> into which additional components, such as a heating element and/or electric insert and/or couplings may be received. For example, the dielectric layers <NUM> may define an upper inner surface <NUM> while the lower shell layer <NUM> may define a lower inner surface <NUM> forming a pocket within which a portion of the electrical insert may be received and electrically coupled to the heating element, grounding strap or conductive layer, and electric insert. In preferred embodiments, the conductive layers <NUM>/<NUM> may also be substantially rigid to enable the conductive layers <NUM>/<NUM> to be temporarily or permanently removed from the outer shell layers, e.g. by peeling.

The interior surface <NUM> of the shell <NUM> may include an inner bond region. The inner bond region may include one or more detachable bonding elements. The inner bond region may prevent slippage (and resulting deformation) between the shell <NUM> and elements positioned in the cavity <NUM>. For example, a weak adhesive layer (e.g. <NUM>™ Pressure Sensitive Adhesive Tapes or <NUM>™ Adhesive Transfer Tapes) may be applied to the upper and/or lower side of the interior surface <NUM>. The inner bond region may correspond to the receiving portion of the perimeter of the shell <NUM>.

The inner bond region can be detachable to enable the shell <NUM> to be separated to provide access to the internal cavity <NUM>. This can allow heating elements to be inserted and/or substituted as need. As well, any thermal insulation layers and/or circuit components may also be access by opening the shell <NUM>. Alternatively, the inner bond region may be omitted. This may facilitate the insertion, removal and/or replacement of components within the cavity <NUM>.

In preferred embodiments, the shell <NUM> may include more or fewer shell layers. For example, the conductive grounding layers <NUM> and <NUM> may be omitted in preferred embodiments.

In preferred embodiments, an additional thermal layer <NUM> may be included in the shell <NUM>, which may function as the dielectric layer. In preferred embodiments, the thermal layer <NUM> may be positioned between the lower protective layer <NUM> and the cavity <NUM> (i.e. where the heating element is to be positioned). Alternatively, the thermal layer <NUM> may be positioned between the upper protective layer <NUM> and the cavity <NUM>. The positioning of the thermal layer <NUM> can be selected based on the desired direction of heating for the heating apparatus <NUM>. The thermal layer <NUM> may be included as a component of the shell <NUM>, or alternatively may be inserted into the cavity <NUM> above or below the heating element.

The thermal layer <NUM> may provide thermal insulation to prevent or at least deter heat from a heating element positioned in the cavity <NUM> from leaking through the lower protective layer <NUM> or upper protective layer <NUM>. This may ensure that a greater portion of the heat from a heating element in the cavity <NUM> is directed towards the surface to be heated. For example, where the upper layer is positioned for snow melt applications, the thermal layer <NUM> may be positioned between the lower protective layer <NUM> and the cavity <NUM> to ensure that more heat is transferred towards the driveway surface on which snow sits rather than downward towards the ground underneath the apparatus <NUM>.

The thermal layer <NUM> material may be manufactured from various thermal insulation materials, such as foams, ceramic fibers, or aerogels. In general, the thermal layer <NUM> material can have a low thermal conductivity and low specific heat capacity. The thermal layer <NUM> material may also be flame retardant. For example, a <NUM> (<NUM> mil) polyamide-aerogel composite film with a thermal conductivity of <NUM> W/mK at room temperature may be used as thermal insulation.

When positioned in the shell <NUM>, the thermal layer <NUM> can be detachably attached to the interior surface <NUM>. The thermal layer <NUM> may also be detachably attached to a heating element positioned in the cavity <NUM>. For example, the thermal layer <NUM> may be attached using a weak adhesive layer such as <NUM>™ Pressure Sensitive Adhesive Tapes or <NUM>™ Adhesive Transfer Tapes. This may allow the thermal layer <NUM> to be removed and/or replaced as desired, while also preventing relative slippage and resulting deformation between the thermal layer <NUM> and other components of the shell <NUM>.

Alternatively, the thermal insulation layer <NUM> may be manufactured as a laminate layer along with the other layers of the shell <NUM>.

Referring now to <FIG>, shown therein is a cross-sectional view of a heating element <NUM>. Heating element <NUM> is an example of a heating element that may be used in embodiments of the heating apparatus <NUM> shown in <FIG>, for example.

The heating element <NUM> can be substantially planar. The heating element <NUM> may also be manufactured of flexible materials to facilitate insertion into the shell <NUM>. For example, the heating element <NUM> may be manufactured as a thick-film printed electronic heating element. The heating element <NUM> may also be manufactured using various flexible planar materials such as conductive films, laminates and non-woven or woven fabrics. Alternatively, the heating element <NUM> may be a rigid heating element.

In general, the heating element <NUM> can include one or more resistive or inductive heating conductors <NUM>. For example, a plurality of resistive heating conductors <NUM> may be arranged into an array (e.g. an array of parallel heating elements) in the heating element <NUM>. The particular arrangement of resistive heating conductors <NUM> may be selected based on the desired heating pattern (for example see <FIG>). The heating conductors <NUM> may be operable using AC or DC power depending on the particular embodiment.

In preferred embodiments, the heating conductor <NUM> may be an electric ink, coating, elastomeric, concrete or woven/non-woven fabric covering substantially the entire planar area or in a defined pattern to provide the heating conductors <NUM> of the heating element <NUM>.

The heating element <NUM> may include at least two primary non-heating conductors <NUM> as electric leads (e.g. copper foil strips). The primary non-heating conductors <NUM> provide terminals for the heating conductors that may be connectable to a power source via power and/or control circuitry. In an embodiment of the present invention, the non-heating conductors <NUM> may span the length of the heating element <NUM>. This may allow the heating element <NUM> to be cut to a desired length for installation. For example, two parallel copper foil strips may be used as the lead elements <NUM> along the length of the heating element <NUM> at a clearance distance from both edges depending on the requirements.

In an embodiment of the present invention, the heating element <NUM> may include secondary non-heating conductors <NUM> in direct contact with the primary non-heating conductors <NUM> and heating conductors <NUM>. This may facilitate a reduced voltage drop from the high resistance of the non-heating conductors <NUM> to the lower resistance of the heating conductors <NUM> to prevent overheating and electrical shorts at the interface between them. For example, a silver ink may be used with lower resistance per square in comparison to the heating conductors and higher resistance in comparison to the primary non-heating conductors.

In an embodiment of the present invention, the secondary non-heating conductors <NUM> may extend along the length of the heating element <NUM> in direct contact with the heating conductors <NUM> and primary non-heating conductors <NUM>.

In an embodiment of the present invention, the secondary non-heating conductors <NUM> may be arranged in an interlaced comb spanning the length forming a discretized pattern of short length low-resistance heating elements connected electrically in parallel.

The resistive heating conductors <NUM> can be arranged to be electrically parallel along the length of the heating element <NUM>. This may allow the heating element <NUM> to be cut to a desired length without requiring designated cutting locations or a visual inspection to ensure that the resistive or inductive elements remain electrically connected to the leads <NUM>.

The resistive heating conductors <NUM> may be arranged with a circuit topology that permits the heating element <NUM> to be cut and/or separate parts of the heating element into a desired shape. Various examples of circuit topologies are shown in <FIG>. For example, the heating element <NUM> may be arranged with multiple parallel resistive heating conductors to non-heating conductor bus bars spanning the length, with perpendicular non-heating conductor booth bars connected across in an interlaced comb spanning the length forming a discretized pattern of short length low-resistance heating elements connected electrically in parallel. This may facilitate a surface power or heat flux density, or plurality of densities, of the heating element <NUM>.

In an embodiment of the present invention, as shown in <FIG>, a plurality of heating elements <NUM> of a plurality of apparatuses <NUM> or within a single apparatus may be connected electrically in series or parallel so as to represent a single heating element or apparatus with a plurality of leads that are connectable to power and/or control circuits. Where the heating elements <NUM> or apparatus <NUM> are adjacent to each other, this may facilitate larger or wider apparatuses. Effectively, individual heating elements or apparatuses can operate as a single appliance over a larger area. It will be understood that there may be multiple heating elements within an apparatus as well as multiple apparatuses within a particular installation.

In an embodiment of the present invention, a plurality of heating elements <NUM> may be stacked vertically (such as, for example, laminated) to facilitate operation of the heating apparatus <NUM> at different power or heat flux densities without changing AC or DC voltage. For example, in under floor heating installation, such a layered heating element may be operated at <NUM> Watts per square foot in higher load applications and <NUM> Watts per square foot in lower load operation.

In an embodiment of the present invention, a thermal layer with insulating properties may be placed between two heating elements <NUM> to facilitate bi-directional heating functionality.

<FIG> shows an example of a heating element having low surface power density with no interlaced comb.

<FIG> shows an example of a heating element with higher surface power density with an interlaced comb topology of non-heating conductors. <FIG> shows another example of a heating element with higher surface power density with an interlaced comb topology. The interlaced comb topology shown in <FIG> may facilitate cutting and/or separating parts of the heating element into a desired shape while still ensuring that the primary non-heating conductors <NUM> retain electrical continuity.

In preferred embodiments, the heating element <NUM> can be manufactured of materials that exhibit self-regulating properties such that the electric resistance is variable with temperature. The heating conductors <NUM> of the heating element <NUM> may be self-regulating such that the electric resistance is variable with temperature. For example, a resistive heating conductor may be manufactured of Positive Temperature Coefficient (PTC) materials formulated using carbon pastes such as Dupont <NUM> or Henkel LOCTITE® ECI <NUM>. This may further improve efficiency by avoiding or reducing switching latencies.

In preferred embodiments, the PTC materials may be dual-phase to provide a primary phase for operation and a secondary phase for protection as an electric fuse. For example, the PTC material formulated may provide operation up to a switching temperature at <NUM> degrees centigrade, and a maximum temperature at <NUM> degrees centigrade after which the heating conductor <NUM> made of PTC material becomes a sacrificial electric fuse.

The switching temperature of the resistive heating conductors used may vary depending on the application of the heating apparatus <NUM>. For example, in snowmelt or de-icing applications, a conductive polymer ink with PTC properties and switching temperature of <NUM> degrees centigrade may be used for the resistive heating conductors <NUM>. The switching temperature may be selected to be low so as to prevent heat or fire damage due to overheating at higher temperatures. As well, the surface power density may be decreased around the selected switching temperature to improve efficiency of the heating element <NUM>.

In preferred embodiments, the heating conductors <NUM> of the heating element <NUM> may be a fixed resistance with temperature and regulated by controller using a thermal sensor such as a thermistor, thermocouple, or resistance temperature device (RTD). In an embodiment of the present invention, fixed resistance heating conductors <NUM> of the heating element <NUM> may be provided for electric resistance heating circuits.

As shown in <FIG>, the heating element <NUM> can also include insulating layers <NUM> and <NUM>. The insulating layers <NUM>/<NUM> may electrically insulate the resistive heating conductors <NUM> from other components of the heating apparatus <NUM>. The insulating layers <NUM>/<NUM> may be manufactured of materials selected to have a thickness and dielectric strength sufficient enough to overcome the voltage breakdown (kV) specified for a particular implementation. For example, a layer of polyethylene terephthalate (PET) or polyamide (PA) may be used for the upper and lower insulating layers <NUM>/<NUM> with thickness and dielectric strength selected to meet a voltage breakdown rating of <NUM>.

In an embodiment of the present invention, the insulating layers <NUM>/<NUM> may be manufactured of fluoropolymer materials selected to have a thickness and lower dielectric constant sufficient to reduce the capacitive reactance and leakage conductance through to the outer surface of the insulating layers <NUM>/<NUM>. For example, a layer of fluoropolymer material such as fluorinated ethylene propylene (FEP) film may provide a dielectric constant between <NUM> and <NUM> at the desired operating frequencies sufficient to achieve lower capacitive reactance and leakage conductance to a conductive covering as part of the shell layer.

In preferred embodiments, the insulating layers <NUM>/<NUM> may have a higher flame retardance than the heating conductors <NUM> and may be deemed halogen-free per environmental, health and safety standards. For example, Dupont Teijin Melinex® FR220 or Saint Gobain ChemFilm® FEP-FG.

In preferred embodiments, the insulating layers <NUM>/<NUM> may also provide other properties and functionalities, such as high or low thermal conductivity and high or low transparency to thermal radiation. In preferred embodiments, the insulating layers <NUM>/<NUM> may also provide on the surface functional electric elements for temperature sensing, force sensing, or even power storage.

The components of the heating element <NUM> may be secured to one another, e.g. using adhesive or hot-melt lamination. The attachment region <NUM>, may be manufactured of adhesive materials having similar flame retardance properties to the insulating layers <NUM>/<NUM>. However, at least one of the insulating layers <NUM>/<NUM> may not be secured to the leads <NUM>. Accordingly, a connection pocket <NUM> may be provided above (or below) each of the non-heating conductors <NUM>. This can allow the leads to be electrically coupled to external circuitry in a preferred direction toward the central region of the shell, and ultimately to a power source.

Referring now to <FIG>, shown therein are examples of insert components that may be used in embodiments of the heating apparatus <NUM> described herein. <FIG> show an exploded perspective and top view of insert components having power coupling components <NUM>/<NUM> with power coupling assembly <NUM>/<NUM> and omitting a controller. <FIG> shows an exploded perspective view and top view of insert components that include a control circuitry and a controller <NUM>.

The inserts shown in <FIG> include substrate layers <NUM> and <NUM>. One or both of the substrate layers <NUM> and <NUM> having insert electrical circuitry thereon or therewithin. The substrate layers <NUM> and <NUM> may be manufactured of flexible or rigid materials. For example, the insert electrical circuitry (e.g. foils) can be converted/laminated with or printed on the substrate layers <NUM> and/or <NUM> using inks. In other examples, the insert electrical circuitry can be assembled using copper bus bars insulated with substrate layer <NUM>/<NUM> and assembled rigidly but also disassemblable.

The circuitry shown in <FIG> includes both power and control circuit components. In preferred embodiments, the control circuitry may be omitted from the insert (as shown in <FIG>) and an external controller (or no controller) may be used to manage the operation of the heating apparatus <NUM>.

The insert electrical circuitry includes non-heating conductors, or electrical terminal components <NUM>/<NUM>. The non-heating conductors <NUM> are configured to be electrically coupled to the non-heating conductors <NUM> of a heating element and non-heating conductors <NUM> to a grounding strap <NUM> or conductive covering <NUM> in apparatus <NUM>. The non-heating conductors <NUM>/<NUM> are coupled to a power supply connector <NUM>/<NUM>, e.g. crimping foil terminal connectors to bare copper foil ribbons or strips placed on the substrates <NUM> and/or <NUM> as a bus. The power supply connector <NUM>/<NUM> can be used to connect the heating element <NUM> to a source of power.

In preferred embodiments, a flat conductor cable may provide the function of insert electrical circuitry having laminated Mylar® substrates <NUM>/<NUM> enclosing a plurality of non-heating copper ribbon conductors <NUM>/<NUM> perforated at insulated regions between them. For example, a CommScope Undercarpet Flat Conductor Cable (FCC) <NUM>-<NUM> (<NUM>-conductor) or <NUM>-<NUM> (<NUM>-conductor) may be used to connect a plurality of heating elements <NUM> within the apparatus <NUM> and connect between apparatuses <NUM>.

The insert circuitry may also be powered from an external power source. Additional or alternatively, a battery may be included in the insert to provide sufficient power for the electronics and/or microcontrollers on the insert.

The non-heating conductors <NUM> from the heating element <NUM> may be connected to the non-heating conductors <NUM>/<NUM> on the insert using conductive terminal couplings or connectors <NUM>/<NUM>. For example, foil terminal butt splice connectors, or conductive foils (e.g. copper foils) mechanical riveted or with conductive adhesives (e.g. a conductive acrylic adhesive backing) may be used to connect the leads <NUM> and the terminal coupling components <NUM>. In some examples, Tyco TERMI-FOIL connectors or CommScope Undercarpet Cabling Splice and Tap Clips may be used. The butt splice connectors may be inserted into the connector pockets above/below the leads <NUM> on the heating element <NUM> and crimped to the heating element <NUM> and insert.

The terminal couplings or connectors <NUM>/<NUM> connectable to a source of power may be selected based on the desired application. For example, the connector <NUM>/<NUM> may be manufactured using Tyco Electronics Termi-foil AMP connectors crimped onto copper foil buses leading to the non-heating conductors <NUM>/<NUM>. In preferred embodiments, a junction box, cable gland, molded connector, or other external coupling assembly <NUM> may enclose the terminal components <NUM>/<NUM> and terminal coupling or connector <NUM>/<NUM> coupled to a short length of cable with a different external power connector.

In preferred embodiments, a sealing end portion consisting of fusing adhesive tape <NUM> may enclose the terminal coupling components <NUM>/<NUM> and power connector <NUM>/<NUM> that may be coupled to a length of cable with a different external power connector or within a junction box, cable gland, molded covering or other coupling assembly <NUM>. For example, <NUM>™ Scotch™ <NUM> Cable Jacket Repair Tape manufactured of butyl rubber/mastic may be used to electrically seal above and below from water ingress and moisture.

In preferred embodiments, the external power supply connector <NUM>/<NUM> may be part of an insulation piercing foil terminal block as a power coupling assembly <NUM>. For example, a CommScope Power Transition Block <NUM> may be used to pierce the insulation and foils of CommScope Flat Conductor Cable (FCC) to terminate for barrel connection of round wires. Additionally a CommScope Power Whip Kit <NUM> (not shown) may be used to enclose the power coupling assembly <NUM> in the same manner as a junction box, cable gland or other coupling <NUM>.

In preferred embodiments, the power supply connector <NUM>/<NUM> includes a connection to the non-heating conductors <NUM> of the heating element <NUM> and the grounding strap <NUM> or conductive covering layer <NUM>/<NUM> of the shell layer <NUM>. The grounding connector <NUM> may be electrically continuous with the grounding strap <NUM> or conductive covering layer <NUM>/<NUM> (if present) of the shell <NUM>. Similar to the coupling between terminal components <NUM>/<NUM> and the leads <NUM>, the grounding connection <NUM> may be connected to the grounding strap <NUM> or conductive covering layer <NUM>/<NUM> using a foil terminal butt splice connector or conductive foil with a conductive adhesive.

In preferred embodiments, the power supply connector <NUM>/<NUM> may be coupled to a ground fault or residual current device. For example, the connector <NUM>/<NUM> may be coupled to a connector cord with an in-line GFCI rated at 5mA. The insert may also include an on-board controller <NUM>. The controller <NUM> may control operation of the heating element <NUM> when coupled thereto by terminal connections <NUM>. The controller <NUM> may also control the operation of the insert circuitry, e.g. based on data retrieved from on-board or external sensors.

In preferred embodiments, the control circuitry such as controller <NUM> may be a hybrid printed electronic on the flexible insert. In other embodiments, the control circuitry may form part of a membrane switch with a junction box or coupling assembly. Control circuitry may be printed on a membrane switch using inks on a stretchable substrate that can later be thermoformed onto the membrane, referred to as In-mold Electronics (IME). In an embodiment of the present invention, the switching membrane may extend through an aperture in the outer shell rather than the junction box alone.

In a preferred embodiment, heating apparatus <NUM> may use temperature, humidity and/or other sensors. As shown in the example of <FIG>, for example, the insert includes a thermal sensor <NUM> and a moisture sensor <NUM>. In the insert of <FIG>, temperature sensor <NUM> and moisture sensor <NUM> are coupled to the controller <NUM> (e.g. using printed silver ink circuitry). Alternatively, the sensors <NUM> and <NUM> may be connected to an external control unit.

The thermal sensor <NUM> may also be implemented as a sensor and/or thermal switch. For example, a Brewer Science Inflect™ Thermistor may be used as the thermal sensor <NUM>.

The thermal sensor <NUM> may be used to measure the temperature at one or more locations in the heating apparatus <NUM>. For example, the thermal sensor <NUM> may be positioned contacting or adjacent to (i.e. without intervening layers) the heating element <NUM>. Additionally or alternatively, a thermal sensor may be positioned between a thermal insulation layer and the lower layer <NUM> of the protective covering (e.g. just inward of the lower layer <NUM>) to sense the temperature of a surface to be heated. This may be used to determine the thermal insulation efficiency.

The moisture sensor <NUM> may be used to measure humidity on the insert circuitry. For example, a Brewer Science Inflect™ Moisture Sensor may be used and connected directly to the insert circuitry.

Additional or alternative sensors may also be used with the heating apparatus <NUM>. For example, force sensors may be included with the insert circuitry to operate as input components. The force sensors may be used to activate/deactivate and/or adjust operational settings of the heating apparatus <NUM>. For example, circular force sensors may be printed onto the insert circuitry.

<FIG> shows a thermal sensor <NUM> on a separate substrate <NUM> that may also have additional electric circuitry such as other sensors, actuators and conductors brought into the coupling assembly <NUM>.

Output components <NUM> may also be included in the insert circuitry. For example, LEDs or electroluminescent displays may be included in the insert to provide outputs indicating on/off state, surface temperature, control settings etc. For example, a printed thin-film <NUM>-channel <NUM>-segment electroluminescent display may be used with the insert.

The insert may also include upper and lower insulation layers similar to the heating element <NUM>. The upper and lower insulation layers may substantially enclose and electrically isolate the insert electrical circuitry from other components in the heating apparatus <NUM> (other than at desired locations). As with the heating element <NUM>, the upper and lower insulation layers can be manufactured from materials exhibiting a thickness and dielectric strength sufficient enough to overcome the voltage breakdown (kV) specification (e.g. <NUM>. 5kV) of the apparatus <NUM>.

In general, the circuitry on insert <NUM> may be enclosed within waterproof protective layers. However, exposed regions <NUM> may be left on insert to allow the terminal connections <NUM> and ground connections <NUM> to be coupled to other components in heating apparatus <NUM>. The exposed regions may have their perimeters sealed in a waterproof manner to prevent damage to other, unexposed, regions of the insert. As a skilled reader will appreciate, the waterproofing used in a particular implementation of an insert may vary based on the components of the insert, as well as the manner in which the insert is manufactured.

In preferred embodiments, sensors and/or actuators included in insert, such as moisture sensor <NUM> may need to be exposed to environmental components external to the insert. Accordingly, a waterproof membrane <NUM> may be provided around the edges of such components (although, the waterproof membrane <NUM> may be moisture permeable to allow a moisture sensor <NUM> to function). Where such components extend through additional layers of the heating apparatus (e.g. through apertures <NUM>), the edges of the aperture <NUM> and sensor member <NUM> can be sealed using a waterproof sealant or tape <NUM>. For example, <NUM>™ Scotch™ <NUM> Cable Jacket Repair Tape may be used in and around the sensors and actuators as well as the junction box or membrane switch itself.

<FIG> shows a hemispherical waterproof membrane <NUM> containing the humidity and precipitation sensor <NUM> and LED <NUM>, while acting as an on-off button. On a separate substrate <NUM>, the thermal sensor <NUM> may be positioned with additional electric circuitry such as other sensors, actuators and conductors brought into the coupling assembly <NUM>. Additionally, an electric relay <NUM> may be included within the coupling assembly <NUM> electrically connected to the insert circuit and controller to turn on/off the apparatus.

The insert <NUM> may typically be inserted into heating apparatus <NUM> just below the first upper layer <NUM>. This may allow components from the insert, such as junction boxes or coupling assemblies <NUM> and/or sensors to extend through apertures <NUM> without interfering with the operation of other layers in the heating apparatus <NUM>.

It should be noted that the terms "coupled" or "coupling" as used herein can have several different meanings depending in the context in which these terms are used. For example, the terms coupled or coupling may be used to indicate that an element or device can electrically, optically, or wirelessly send data to another element or device as well as receive data from another element or device.

It should be noted that terms of degree such as "substantially", "about" and "approximately" as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. These terms of degree may also be construed as including a deviation of the modified term if this deviation would not negate the meaning of the term it modifies.

Furthermore, any recitation of numerical ranges by endpoints herein includes all numbers and fractions subsumed within that range (e.g. <NUM> to <NUM> includes <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>). It is also to be understood that all numbers and fractions thereof are presumed to be modified by the term "about" which means a variation of up to a certain amount of the number to which reference is being made if the end result is not significantly changed.

In addition, as used herein, the wording "and/or" is intended to represent an inclusive-or. That is, "X and/or Y" is intended to mean X or Y or both, for example. As a further example, "X, Y, and/or Z" is intended to mean X or Y or Z or any combination thereof.

The terms "an embodiment," "embodiment," "embodiments," "the embodiment," "the embodiments," "one or more embodiments," "preferred embodiments," and "one embodiment" mean "one or more (but not all) embodiments of the present invention(s)," unless expressly specified otherwise.

Claim 1:
A planar electrical heating apparatus (<NUM>) operable using AC or DC power comprising:
an outer shell (<NUM>) with an upper shell layer (<NUM>) and a lower shell layer (<NUM>) defining an internal cavity therebetween having an upper inner cavity surface facing a lower inner cavity surface, each upper and lower inner cavity surface having a first attachment region in which the upper inner cavity surface and the lower inner cavity surface is attachable along a periphery and a second attachment region in which the upper inner cavity surface and the lower inner cavity surface is detachable over a central area of the internal cavity,
wherein the first attachment region has a first bond between the upper inner cavity surface and the lower inner cavity surface at least as strong as a second bond of the second attachment region between the upper inner cavity surface and the lower inner cavity surface;
a heating element (<NUM>) positionable within the internal cavity between the upper shell layer and lower shell layer, the heating element having a heating conductor and a first and a second non-heating conductor;
a first connector end portion secured to the first and the second non-heating conductor for coupling to an electrical power supply; and
a sealing end portion (<NUM>) enclosing the connector end portion for electrical isolation and protection from water ingress.