Conduit ready electric belly band heater using single housing and method of use

An electric belly band heater is configured with only one end of the heater cable assembly thereof having lead wires extending therefrom. A single housing box is positioned at the end of the heater cable assembly where the lead wires exit to encompass the lead wires and includes an opening to receive a conduit to provide further protection to the lead wires exiting the housing box and being connected to a power source.

FIELD OF THE INVENTION

The present invention is directed to an electric belly band heater that uses a single housing to facilitate the use of a conduit for the lead wires of the band heater.

BACKGROUND ART

U.S. Pat. No. 6,844,531 to Kirby discloses a belly band heater that uses a pair of conduit boxes, one box for each lead wire. The heater cable of the band heater is encased in a metal sheath and the resistance wire exits the metal sheath and is housed at the exit point by the conduit box. The conduit box can receive a conduit that the lead wire can pass through for connection to a power source. In certain applications, the use of two conduit boxes is not possible and the belly band heater of Kirby needs improvement.

Other belly band heaters use a heater cable assembly with two resistance wires therein, see U.S. Pat. No. 6,557,620. These heaters then have one end where the two resistance wires are internally connected and another end where two wires extend from the end for connection to the appropriate power source. The heater cable assembly of this heater is held together using a spring fastener and these fasteners are problematic.

SUMMARY OF THE INVENTION

The present invention is an improvement over the belly band heater of Kirby. The inventive belly band heater uses a single housing box to house two wires extending from an end of the heater cable assembly of the heater. The inventive belly band heater also uses silicone housed resistance wire(s) and zip tie segments to attach the ends of the heater cable assembly together.

The housing box is preferably made as a two part assembly to ease the assembly of the belly band assembly on a structure to be heated and handling of the wires exiting one end of the heater band assembly of the heater. A base part of the housing box is configured so that the surface that contacts the structure can flex to accommodate surfaces that are not flat.

The inventive heater can be used in any application where a structure needs to be heated by surrounding the structure with the heater cable assembly of the heater, positioning the housing box at one of the heater to house the ends of the wires exiting the end of the heater cable assembly and allowing a conduit to be attached to the housing box to allow the wires to extend from the housing box and through the conduit for connection to a power source.

DETAILED DESCRIPTION OF THE INVENTION

The inventive electric belly band heater provides an improved heater cable assembly designed to heat a structure such as a compressor or the like.

The heater cable assembly uses the basic manner to secure the ends of the heater cable assembly as disclosed in U.S. patent application Ser. No. 14/136,035, which is incorporated by reference in its entirety into this provisional application and a copy of the application is attached herewith for this purpose.

The feature of this application that is used in the invention is the use of zip tie segments to facilitate attaching and tightening of the heater cable assembly of the heater on a desired structure. That is, one end of the heater cable uses a male end of a zip tie and the other end of the heater cable employs the female end of a zip tie. The male end is slipped through the slot in the female end and pulled to tighten the heat cable assembly on the structure intended to be heated.

While the prior art teaches that a lead wire extends from each end of the heater cable, the inventive cable is configured so that both lead wires extend from only one end of the heater cable assembly. In conjunction with this sole exit point for the lead wires, a single housing box is employed to provide protection for the lead wires extending from one end of the heater cable assembly and accommodate the use of a fitting for a conduit so that the lead wires are protected not only when in the housing box but also when extending from within the housing box to a power source connection.

Each end of the heater cable assembly is uniquely configured to allow for the wires to extend from just one end of the heater cable assembly and allow for a robust linking of the heater cable ends using the zip tie segments.

It should be understood here that the arrangement of the zip tie and the heater cable ends can vary. That is, the end of the heater cable assembly that includes both lead wires extending therefrom can have either the male or the female part of the zip tie. Similarly, the end of the heater cable assembly that does not have any lead wire extend therefrom can use either the male or the female end of the zip tie. For description purposes, the end of the heater cable assembly that has no lead wires is shown with the male end and the end of the heater cable assembly with the two lead wires extending therefrom is shown with the female end of the zip tie but the invention is not so limited.

FIG. 1shows a prior art silicone heater cable assembly10having a silicone insulation1, which is in the shape of an I-beam. The silicone insulation1surrounds a fiberglass braid3, which in turn surrounds a resistance wire5. It should be understood that the resistance wire5can take the form of a wire that is helically wound on a fiber center core, which acts as an arbor. Hereinafter, either embodiment, a solid resistance wire or the helically wound wire on the core are called a “resistance wire.” Since the helically wound resistance wire is well known by itself, an illustration is not deemed necessary for understanding of this embodiment. In fact, any type of resistance wire used in these types of band heaters is suitable for use herein. The resistance wire, when supplied with power, generates heat, which is conducted through the silicon insulation to the structure that would be in contact with face6of the heater cable10.

FIG. 2shows the end of the heater cable assembly10, where a portion of the silicone insulation is removed to expose the fiberglass braid3, wire5, and end face39of the insulation. A portion of the fiberglass braid3is removed to produce a bare wire for splicing to a lead wire.

FIG. 3shows an example of a connection9between the exposed end8of the wire5and the lead wire7. A metal crimp11, as is known in the art, is used to mechanically link the end8of the wire5to the end of the lead wire7.

InFIG. 4, a heat shrink tubing13can be used to surround the crimp11and exposed fiberglass braid3to make the connection strong.

InFIGS. 3 and 4, the fiberglass braid3is shown in combination with the resistance wire5and silicone insulation1. However, the braid3could be omitted so that only the wire5and the silicone insulation1are used for heating purposes.

In addition, inFIG. 3, the fiberglass braid3is shown to surround the wire5when the silicone insulation1is removed. However, the fiberglass braid3could also be removed with the silicone insulation1such that the bare resistance wire end8extends from the end of the silicone insulation1that still covers the resistance wire5.

The band heater assembly of the invention uses a zip tie to secure ends of the heater cable10together, as seen inFIGS. 5aand 5b. Here, a zip tie is cut into two segments, a first zip tie segment21and a second zip tie segment23. The segment21includes the head end25with its slot27and a tape section29, which is used to attach to one end of the heater cable10.

The other zip tie segment23just comprises a tape section31having a length so that the end of the tape section31can be inserted into the slot27of the head end for pulling of the ends of the heater cable assembly10together and clamping the heater cable assembly to a structure for heating. It should be understood that the tape section includes the teeth that engage in the slot27, although the teeth are not illustrated since this configuration is well known in the field of zip ties. One zip tie segment21has a throughhole33and the other zip tie segment has two throughholes35and36.

The throughhole33and zip tie segment21is designed to interface with the end of the heater cable that does not have a lead line extend therefrom. The zip tie segment23with two openings is designed for use with the end of the heater cable assembly that has both lead lines extending therefrom. In the alternative, one throughhole could be used to allow both lead wires to pass therethrough.

The throughholes33,35, and36are sized to permit a given lead wire7to pass therethrough to enhance the attachment of each tape section29and31to each splice connection9. The fact that the wire7is pulled through the hole33in the zip tie segment21and then molded into place, as detailed below, means it would take extreme tension to pull the zip tie loose and therefore the zip tie can provide the strength needed while the zip tie is being pulled into place on a given structure, e.g., a compressor shell.

Referring toFIG. 6, the end37of the tape section29of the zip tie segment21is butted against the end face39, seeFIG. 2, at41and the lead wire7extends through the opening33in the tape section29. InFIG. 6, it should be noted that the connection9is disposed between the tape section29and a structure (not shown) so that the face6of the heater cable10would rest on the structure when the band heater is in place for heating. In this way, the heated portion of the band is adjacent to the structure and this forces the heat to move toward the structure and the tape section29is kept cooler during heating operation.

Once the tape section29is in place, the tape section can be overmolded to hold it in place. This overmolding is a well-known technique and is used in other band heaters so that the details thereof are not needed for understanding of the invention. The overmolding layer is shown inFIG. 7as43and the overmolded part of the heating cable assembly having the connection and tape section of the zip tie segment is identified with the reference numeral45. The arrangement shown inFIG. 7is collectively described below as a splice connection, which presents the splice connection and the covering of the splice connection and zip tie segment.

Typically, a silicone molding compound is applied to one side of the assembly and pressed into place. This is followed by a molding compound being applied to the opposite side as well. The silicone molding compound is then pressed and heated so that the material will bond to itself and the components of the heater cable and splice connection. Since the overmolding process would be automated, trimming the molding compound from the heater cable is normally not a requirement. The overmolding process produces a low profile molding that insulates the electrically live portions and bonds the molding compound to the heater band and itself. The overmolding method allows the molding compound to stick to itself during the overmolding step. This adds substantial strength to the band heater assembly. Once the compound cures it is difficult to pull the cured compound through the zip tie segment slot27and break the band heater assembly.

If desired, the overmolded part of the cable assembly can be surrounded with another heat shrink tubing46, which is also shown inFIG. 7. However, the heater cable assembly is perfectly functional using just the splice connection9with its crimp and heat shrink tubing13, and throughhole-containing zip tie segment21. It should also be understood that for the splice connection9, it is possible to use just the metal crimp to attach the ends of the lead wire7and the resistance wire5together, but the use of the heat shrink tubing13does improve the connection.

The overmolding43can be trimmed to size so that it is more similar in shape to the heater cable10. This also helps in reducing any fit problems with the band heater and the structure intended to receive it.

The assembly shown inFIG. 7is similar to that for tape section31of the zip tie segment23. The main difference though would be that the end of the lead wire running through the heater cable assembly would also pass through the tape section31and along with the lead wire connected to the other end of the resistance wire and prior to extending from one of the ends of the heater cable assembly.

Another difference is that the zip tie segment23is designed to handle two wires since there are two wires extending from the end of the heater cable assembly. This is contrast to the other end of the heater cable assembly, wherein the zip tie segment interfaces with the lead wire, but only the zip tie segment extends from the splice connection to facilitate linking of the ends of the heater cable assembly.

Still with reference toFIG. 7, the lead wire7, after passing through the zip tie segment opening33reverses its course and runs along the length of the heater cable assembly10and exits the other end of the heater cable assembly10to pair with the exiting lead wire that is spliced to the resistance wire at the other end of the heater cable assembly10.

The lead wire7can be held with the heater cable10by the use of the high temperature heat shrink tubing46. Since the lead wire runs with the heater cable assembly, the heat shrink wrap would extend along the length of the heater cable assembly so that the lead wire7is made an integral part thereof. The doubled over lead wire could be covered with the molding compound43and then covered again with the heat shrink tubing so that it is an integral part of the heater cable assembly10. While it could be possible to incorporate the lead wire7into the silicone insulation when making the heater cable assembly, this would also require making the splice connection and including the zip tie segment as part of this manufacture so that the end of the heater cable only has the zip tie segment extend therefrom.

For disclosure purposes, the splice connection can include the components described above to make the connection, i.e., the metal crimp, heat shrink tubing, molding compound, etc.

In theFIGS. 2-7embodiment, one lead wire runs with the resistance wire along the length of the heater cable assembly so that there is only the zip tie segment that extends from the one end of the heater cable assembly.

However, heater cable assembly inFIG. 7could be replaced with a dual resistance wire heater cable. In this embodiment, the two resistance wires are either spliced or the heater cable is made so that the resistance wire reverses course at the end of the heater cable lead wire. Preferably, a splice connection is made similar to that shown inFIG. 7so that the engagement between the resistance wires and zip tie segment can occur to strengthen the attachment of the zip tie segment to the heater cable assembly.

This second embodiment of the invention, shown inFIGS. 8 and 9, involves using a pair of resistance wires51and53running through the heater cable54. With this embodiment, one end of the heater cable assembly would include a splice to connect the two resistance wires together and the two wires would interface with the tape section of a zip tie segment.

The other resistance wires would extend from the other end of the heater cable assembly, also going through the tape section for connection to lead wires.

Additionally, another advantage associated with the invention shown inFIG. 8is that at least a 2-stage heater can be produced.FIG. 9shows a schematic drawing of the arrangement of the lead wires with the splice connection58between the two resistance wires51and53on the left side of the drawing and the terminating ends of the two wires on the right side of the drawing having the designations L2 and L2. Now, more than a one stage heater is possible. In addition, thermostat controls to turn all or part of the heaters on and off based on temperature and demand could be included to thereby improve the efficiency and performance. This is a significant advantage over prior art heaters like that shown in U.S. Pat. No. 7,442,904 to Kirby. The Kirby patent is only a single stage heater so that all of the heat for the structure to be heated is either being applied or not being applied. With the two stage heating capability ofFIGS. 8 and 9, the heater provides multiple heaters that can be turned on and off using the appropriate controls. For example, either or both of the circuits shown inFIG. 9could be powered for heating purposes.

In theFIGS. 8 and 9embodiment, there is no lead wire splicing at the one end of the heater cable like in the embodiments discussed above. The only splice connection would be between the two resistance wires of the heater cable assembly. This splice connection could be made just like the splice connection described above when using a lead wire and a resistance wire.

In combination with the heater cable assembly described above having one end with one half of the zip tie and no extending wires, and the other end of the heater cable with the two wires extending therefrom is a housing box. The housing box is designed to encompass the exiting wires from the end of the heater cable assembly so as to protect them and also serve as a way to connect a conduit so that the wires extending from the heater cable end are not only protected by the housing box but are also protected when exiting the housing box by virtue of a conduit coupled to an opening in the housing box.

While the housing box could be a one piece box, a preferred embodiment of the housing box is a two part box. One part serves as a base part that allows for easier interfacing with the wires extending from the end of the heater cable assembly. The base part also is designed such that it can flex and adapt to a surface of the structure that is being heated using the heater cable. The top part is removably attached to the base part. With the top part not yet secured to the base part, the wires can be easily pulled through the opening in the top part and then the top part can be attached to the base part. Of course, the top part could be attached first and then the wires extending from the end of the heater cable assembly could be passed through the opening. Further yet, a one piece housing box could allow the zip tie segment and wires to pass through the housing box so that the end of the zip tie segment can be used for attachment purposes and the lead wires can extend through a conduit.

FIGS. 10A and 11show drawings of the base part100and top part102. The base part100has a base plate103, and two sides105. The sides105are joined to the base plate103at the junction107. This creates cutouts or spaces109that run along the length of the base part100. These cutouts109allow the base plate103to flex and adapt to a curved surface like that of a compressor. The sides105include flanges110, which form a surface to allow for attachment of the top part102. The flanges include openings111to receive a fastener, e.g., a screw to allow the top part to be removably attached to the base part. The cutouts are one way to provide flex in the base plate to allow the base plate to flex but other ways could also be employed as well, e.g., make the base plate of a flexible enough material that it will flex, add additional cutouts in the base plates, seeFIG. 10Bbelow.

The top part102includes a top portion113and two sides115. The sides115cooperate with the sides105of the base part to form a surrounding wall, which forms a housing box with the base part plate and top portion113. The top portion113also includes an opening117and attachment facilitating openings119. The openings119allow for passage of a screw, the screw threading to the openings111in the base part100.

The opening117allows the wires extending from the end of the heater cable assembly to exit the housing box formed by the top and base parts100and102. A conduit can be attached to the opening using the appropriate fitting as is known in the art so that the wires extending from the end of the heater cable assembly are protected both in the housing box and in the conduit.

It should be understood that the sides115of the top part102are sized so that the end of the heater cable can be enclosed in the interior of the housing box so that the wires are also enclosed. This means that one side is sized to allow the heater cable assembly to pass under the side115and that the zip tie segment of this end of the heater cable assembly can pass through the other side115so that the two zip tie segments can be linked together and the heater cable assembly secured to the structure to be heated.

The overall height of the sides can be adjusted to allow for passage of the heater cable assembly or the sides can include cut outs124, shown in cross hatch inFIG. 11to allow for passage of the tape section or the heater cable assembly.

The base part100can be held in place by the action of the zip ties tightening the heater cable around the desired structure. In the alternative, the base part could be attached to the structure in some fashion to hold it in place, e.g., fasteners, adhesive, welding, rivets, etc.

FIG. 10Bshows another embodiment of the invention. In this embodiment, additional cutouts104, which are separated by a center portion106are formed in the base plate103′ to enhance the flexing and accommodation to structures that are not flat. A further variation of the embodiment ofFIG. 10Bcan be seen inFIG. 10C. Here, back plate103′ has a center portion106′. The portion106′ is made into a curved shape to create a gap between a surface of the structure to be heated and an underside of the portion106′. This gap allows the zip tie segment tape section29to pass under the portion106′ and be held in place. In an alternative, the zip tie could be riveted to the back plate103that is shown inFIG. 10A.

FIGS. 12-15show schematically the two embodiments of the invention. InFIGS. 12 and 13, the lead wire121is part of the heater cable assembly and this lead wire121extends through the zip tie segment23as described above. However, it could be that both the lead wire121and the resistance wire123extend through the zip tie segment23, either through separate holes or one hole to give further strength when the heater cable ends are connected.

While a straight splice125is shown between the lead wire121and the resistance wire123, where the lead wire makes an 180 degree bend, another splice configuration could be used to eliminate the 180 degree bend, i.e., use a u-shaped metal crimp rather than a straight one as described above. Alternatively, a butt connector, which would be the equivalent of using a wire nut to make the connection between the lead wire and the resistance wire could be used, thus eliminating the bend.

FIG. 13shows the other splice127for the lead wire129to the resistance wire and placement of the housing box131, the overmolding135, and conduit137.

FIGS. 14 and 15show the embodiment wherein the resistance wires139are spliced together at141on the overmolded end141of the heater cable that does not have any wires extending therefrom. In this embodiment, the lead wires148are shown passing through the zip tie segment21inFIG. 15, with the splices143and145preceding the passing through. The housing box147and overmolding149are also illustrated. However, one or both of the resistance wires at the splice end could go through the zip tie segment, and the splice would be downstream of the pass through of the zip tie segment. With both of the wires going through the zip tie segment, additional strength is obtained for the tightening of the heater cable assembly.

FIG. 16shows the heater cable assembly, including the heater cable14, surrounding a structure151with the zip tie segments21and23connected and the lead wires121and129extending from the overmolding135. This configuration is similar to that shown inFIG. 13except that the overmolding135also covers where the wire129passes through the zip tie segment21, and the housing covers part of the overmolding. The structure151is typically a compressor but it can be anything that requires heating from the heater cable assembly. The base plate100is depicted without the top part102.FIG. 17shows the top part102in place with the lead wires121and129extending from the opening117in the top part102. The housing box is normally made out of the typical materials used for electrical connections but it could be made of a non-metallic material, e.g., a plastic material. The housing box could also be used in a retrofit fashion, wherein an existing belly band heater could be modified to use the single housing box.

The invention provides significant advantages over the prior art in the use of one housing box, the ability for a two stage heater, and the ability of the housing box to more easily adapt to surfaces that are not flat.

More particularly, one advantage for the inventive heater is the conduit housing construction. As is known in the art, the typical installation for a belly band type heater is attachment to a compressor, which could have a cylindrical shape or at the very least a curved outer shape of some type. One typical problem with the conduit boxes used in prior art heaters is the fact that the conduit box is normally flat and is attached to a curved shape. This attachment can leave a gap behind the conduit box as it does not easily contour to match the compressor shape. This leaves the designer with having to make a recessed type box to fit the contour, but this can really only fit specific contoured shapes and certainly could not be extremely flexible and able to contour too many different shapes. The gap can be envisioned by placing a ruler on a cylinder and a space will extend from the tangent point along the ruler.

This design of the inventive heater cable assembly allows for the heater conduit box to easily conform to the contoured shapes. The inventive conduit box can actually have four sides as well as a top and bottom. The bottom portion would be preferably located behind the zip tie segment used to tighten the assembly. Additionally, the conduit box bottom, with its cut-outs, is designed in such a way as to contour to the compressors (or item to be heated) shape, as the band is tightened.

As such, an invention has been disclosed in terms of preferred embodiments thereof which fulfills each and every one of the objects of the present invention as set forth above and provides a new and improved belly band heater cable assembly and method of use.

Of course, various changes, modifications and alterations from the teachings of the present invention may be contemplated by those skilled in the art without departing from the intended spirit and scope thereof. It is intended that the present invention only be limited by the terms of the appended claims.