WO2019213561A1 - Heating element system, method for assembly and use - Google Patents

Abstract

A heating element system includes a spiral heating element joined to a bridge assembly which extends to offset terminal ends having end-grooves for receiving metal bonded electrical wires for power transfer. Electrical inductance is lower in the bridge assembly and the terminal ends than in the spiral heating element, allowing for localized controlled heating. In assembly the elements are combined in a monolithic assembly with ceramic paste and the wires are secured to the terminal ends using a metalized spray bonding method.

Description

HEATING ELEMENT SYSTEM, METHOD FOR ASSEMBLY

AND USE

CROSS REFERENCE TO RELATED APPLICATIONS

[001] This application relates to, and claims priority from, US Prov. Ser. No.: 62/666,196 filed May 3, 2019, the entire contents of which are incorporated herein by reference.

FIGURE SELECTED FOR PUBLICATION

[002] Fig. 13

BACKGROUND OF THE INVENTION

Field of the Invention

[003] The present invention relates to an improved heating element system, method for assembly and the use of the same. More particularly, the present invention provides a silicon carbon related heating element bridge structure and electronic coupling system with improved durability.

Description of the Related Art

[004] Industrial applications of silicon carbide (SiC) heating elements are known, for example from type SER and TSR, SiC Spiral Heating elements as illustrated in I Squared R Element Co, Inc. brochure ST-SER-Rev. 5.doc.

[005] Referring now to Figs. 1, 2, 3, 4, and 5, exemplary known spiral type SiC heating elements 1 are providing with an outer diameter, an inner diameter, and a spiral grove or cut about a portion of the circumference forming an electronic pathway from one leg-end post 2 to another leg-end post 3. Electronic coupling devices 4 are directly clamped to the ends of posts 2, 3 for transmission of electrical current causing resistive heating of the spiral grove-region. [006] Conventionally, the heating element 1 are brittle so that connection of the electronic/electric coupling devices 4 caused pressure under tension from a hose clamp 5, which was resisted by an electrically insulating inner plug 6. In an arrangement with a furnace 7, with a plurality of heating elements 7 from a top- down suspension mode, a further insulating monolithic collar 8 is provided to secure heating elements 1 in position on furnace 7. As a further concern in the conventional arts collar 8 is difficult to secure, and provides operational difficulties.

[007] As an additional concern, in certain applications, gaseous chemical residues evolve from the thermal process (inside a kiln, oven etc.) and condense on the‘cold’ ends which are the electric coupling devices 4 in the prior art. This residue has a number of detrimental results on operations, including the formation of electrical arcs across the slit/slot between the coupling ends 4, 4. Electrical arcs across this slit/slot between the narrow prior art coupling ends provides a catastrophic failure and loss of the heating element 1 (which in turn is a large financial loss in operational time for the repair and financial loss in terms of the element and equipment, some of which go through an irreversible phase transformation reaching operational temperature and thus in cooling for repair of a single element can require the complete replacement of the entire kiln or oven).

[008] Referring now to Figs. 4, 5, where a spiral type igniter 1 is also used in the form of a gas igniter as noted in US 3,928,910 (Peri), the entire contents of which are incorporated herein by referenced as to structure, assembly, spray bonding and related assembly techniques. As shown in Figs. 4, 5, small end-grooves 11, 11 are formed by cutting at the end of each leg-end 2, 3 of the spiral heating element. Electrical connectors 12, 12, are held in place therein, and using a spray bonding process noted in the‘910 patent, shown as spray bonded material 13 are secured in place forming a reasonably secure electrical connection between connectors 12, 12, and ends 2, 3 of heating element 1. Unfortunately, this technique has substantive quality control detriments, experiences substantial thermal degradation, allows very little surface connection, and causes electrical arcing with any fault and provided only a temporary electronic linkage within a hot furnace-atmosphere that may rise as high as 1600°C

[009] Accordingly, there is a need for an improved heating element system, method for assembly and use.

ASPECTS AND SUMMARY OF THE INVENTION

[0010] In response, it is now recognized that there is a news for improved heating element, method of assembly and use thereof.

[0011] According to one aspect of the present invention, there is provided a heating element system that includes a spiral heating element joined to a bridge assembly which extends to offset terminal ends having end-grooves for receiving metal bonded electrical wires for power transfer. Electrical inductance is lower in the bridge assembly and the terminal ends than in the spiral heating element, allowing for localized controlled heating. In assembly the elements are combined in a monolithic assembly with ceramic paste and the wires are secured to the terminal ends using a metalized spray bonding method.

[0012] According to another alternative aspect of the present invention, the current bridge assembly or arrangement provides the spiral ends fully in a‘hot zone’ thereby preventing gaseous chemical residues from condensing therein because the temperature is much too high (much hotter than the‘cold ends’ forming the electrical coupling).

[0013] According to another alternative aspect of the present invention, the thermal bridge assembly or arrangement is particularly useful in a hot environment (kiln, oven etc.) where organic binders are being removed from pressed or extruded parts formed from powdered metal or ceramic particle compositions. This problem is particularly acute where there is a process for rapid binder removal from automated printed (3D printed etc.) because the temperatures involved in rapid binder removal can cause a rapid buildup of carbonaceous deposits.

[0014] According to another alternative and adaptive aspect of the present invention, there is provided a heating element system, comprising: an electrically conductive spiral helix heating element having a spiral hot end and an opposed cool ending having a first cool side and a second cool side; said electrically conductive spiral helix heating element having a first heating element electrical resistance; an electrically conductive first bridge member chemically bonded to extending from said first cool side and away from said hot end; an electrically conductive second bridge member chemically bonded to and extending from said second cool side and away from said hot end and said first bridge member; each said first bridge and said second bridge having a second bridge electrical resistance; said second bridge electrical resistance being less than said first heating element electrical resistance; a first electric terminal extending from said first bridge member; a second electric terminal extending from said second bridge member; each said first electrical terminal and said second electric terminal having a third electric terminal electrical resistance; said third electrical terminal electrical resistance being the same as or less than said second bridge electrical resistance; a first electrical connector joined to said first electrical terminal at a first receiving profile geometry; a second electrical connector joined to said second electrical terminal at a second receiving profile geometry; each said first electrical connector and said second electrical connector having a fourth electrical resistance; and said fourth electrical resistance being the same as or less than said third electrical terminal electrical resistance.

[0015] According to another alternative and adaptive aspect of the present invention, there is provided a method of assembling a heating element system, comprising the steps of: providing an electrically conductive spiral helix heating element having a spiral hot end and an opposed cool ending having a first cool side and a second cool side; said electrically conductive spiral helix heating element having a first heating element electrical resistance; providing an electrically conductive first bridge member chemically bonded to extending from said first cool side and away from said hot end; providing an electrically conductive second bridge member chemically bonded to and extending from said second cool side and away from said hot end and said first bridge member; each said first bridge and said second bridge having a second bridge electrical resistance; said second bridge electrical resistance being less than said first heating element electrical resistance; providing a first electric terminal extending from said first bridge member; providing a second electric terminal extending from said second bridge member; each said first electrical terminal and said second electric terminal having a third electric terminal electrical resistance; said third electrical terminal electrical resistance being the same as or less than said second bridge electrical resistance; providing a first electrical connector joined to said first electrical terminal at a first receiving profile geometry; providing a second electrical connector joined to said second electrical terminal at a second receiving profile geometry; each said first electrical connector and said second electrical connector having a fourth electrical resistance; and said fourth electrical resistance being the same as or less than said third electrical terminal electrical resistance.

[0016] According to another alternative and adaptive aspect of the present invention, there is provided a heating element assembly, comprising: an electrically conductive spiral helix heating element having a spiral hot end and an opposed cool ending having a first cool side and a second cool side; said electrically conductive spiral helix heating element having a first heating element electrical resistance; an electrically conductive first bridge member chemically bonded to extending from said first cool side and away from said hot end; an electrically conductive second bridge member chemically bonded to and extending from said second cool side and away from said hot end and said first bridge member; each said first bridge and said second bridge having a second bridge electrical resistance; said second bridge electrical resistance being less than said first heating element electrical resistance; a first electric terminal extending from said first bridge member; a second electric terminal extending from said second bridge member; each said first electrical terminal and said second electric terminal having a third electric terminal electrical resistance; said third electrical terminal electrical resistance being the same as or less than said second bridge electrical resistance; a first electrical connector joined to said first electrical terminal at a first receiving profile geometry; a second electrical connector joined to said second electrical terminal at a second receiving profile geometry; each said first electrical connector and said second electrical connector having a fourth electrical resistance; and said fourth electrical resistance being the same as or less than said third electrical terminal electrical resistance.

[0017] The above and other aspects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Fig. 1 is a conventional furnace arrangement with heating elements.

[0019] Fig. 2 is a conventional heating element.

[0020] Fig. 3 is a top end perspective view of Fig. 2.

[0021] Fig. 4 is an alternative conventional heating element with electrical links.

[0022] Fig. 5 is a close up conventional view of Fig. 4 following a coating bonding application. [0023] Fig. 6 is a new heating element system according to the present invention from a top plan orientation with terminal ends, bridge element, and wire leads attached.

[0024] Fig. 7 is the a side view of Fig. 6.

[0025] Fig. 8 is an assembly view of three heating element systems as shown in Figs. 6, 7 in different states of assembly.

[0026] Fig. 9A is a close up perspective image of the terminal ends with partial wire securement in a channel arrangement with bonding material and a stabilizing binding for transport.

[0027] Fig. 9B is a close up perspective image of the terminal ends (as in Fig. 9A) prior to inclusion with the wire leads, bonding material or stabilizing binding.

[0028] Fig. 10 is an assembly schematic noting the position of braided wire ends in the channel of a terminal end feature formed as a partial slot for receiving the loose wire end and combination with a binding agent on each terminal end.

[0029] Fig. 11 is a sectional view of a bridge element assembly along Section line

11-11 in Fig. 6.

[0030] Fig. 12 is a sectional view of a bridge element assembly along Section line

12-12 in Fig. 7.

[0031] Figs. 13, 14 are partial bridge-perspective views from a top-down and bottom up perspective with the heating element and respective terminal ends shown dashed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Reference will now be made in detail to embodiments of the invention. Wherever possible, same or similar reference numerals are used in the drawings and the description to refer to the same or like parts or steps. The drawings are in simplified form and are not to precise scale. The word‘couple’ and similar terms do not necessarily denote direct and immediate connections, but also include connections through intermediate elements or devices. For purposes of convenience and clarity only, directional (up/down, etc.) or motional (forward/back, etc.) terms may be used with respect to the drawings. These and similar directional terms should not be construed to limit the scope in any manner. It will also be understood that other embodiments may be utilized without departing from the scope of the present invention, and that the detailed description is not to be taken in a limiting sense, and that elements may be differently positioned, or otherwise noted as in the appended claims without requirements of the written description being required thereto.

[0033] In the present text, numerous specific details are set forth in order to provide a thorough understanding of exemplary versions of the present invention. It will be apparent, however, to one skilled in the art, that some versions of the present invention may possibly be practiced without some of these specific details. Indeed, reference in this specification to "a variant,"“variants,” and "one/the variant," or "one version," "a version" and the like, should be understood to mean that a particular feature, structure, or characteristic described in connection with the variant or version is included in at least one such variant or version according to the disclosure. Thus, the appearances of phrases such as "in one variant," "in one version," and the like, in various places in the specification are not necessarily all referring to the same version or variant, nor are separate or alternative versions or variants mutually exclusive of other versions or variants. Moreover, various features may be described which possibly may be exhibited by some variants or versions and not by others. Similarly, various requirements are described which may be requirements for some variants or versions, but not others. Furthermore, as used throughout this specification, the terms 'a', 'an', 'at least' do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item, in the sense that singular reference of an element does not necessarily exclude the plural reference of such elements. Concurrently, the term“a plurality” denotes the presence of more than one referenced items. Finally, the terms“connected” or“coupled” and related terms are used in an operational sense and are not necessarily limited to a direct connection or coupling.

[0034] Various operations may be described as multiple discrete operations in turn, in a manner that may be helpful in understanding embodiments of the present invention; however, the order of description should not be construed to imply that these operations are order dependent.

[0035] Referring now to Figs. 6-14 various aspects of the present invention system 200 are provided. As noted a spiral/helix type heating element 100 provides a‘hot-end’ assembly and upon being energized glows brightly to heat a furnace (as in Fig. 1). There is a known resistivity to heating element 100. A bridge member 101 having two sides 101 A, 101B is secured to the respective C- shaped ends of heating element 100, as shown. Bridge member 101, with sides 101 A, 10 IB has a known electrical resistance that is less than heating element 100, so that electrical current easily passes through with minimal heating of the bridge element.

[0036] Two terminal ends or terminal legs 102A, 102B are secured by monolithic molding to off-set locations of bridge member 101, as shown and form a cold-end or cold-side of assembly and system 200. Opposite ends of terminal ends/legs 102 A, 102B are formed with receiving grooves or channels 110A, 110B (as a type of receiving geometry which may also include a hollow-end (not shown but described) a receiving-profile geometry (not shown but described) that are formed into and with the monolithic structure of each terminal end, as a non-limiting example as shown (see Fig. 10 with a trench or groove). Braided wire electrical connectors 115A, 115B (e.g., 10 gauge or other suitable gauge) have an exposed braded wire end (Ni coated Cu wires, or other suitable alloy wire is used for hot oxidizing atmosphere) for chemical metalized spray bonding and electrical conduction to terminal ends 102A, 102B (as will be discussed) upon assembly (e.g., placed within the receiving-profile geometry terminal ends/legs 102A/102B and metalized spray bonded). Upon positioning the braided wire ends are secured on position by a metalized spray bonding to fully cover and fully enmesh terminal leg ends and wires 1 15A, 1 15B forming a monolithic continuous electrical connection from one electrical connection 115A, through bridge 110A, through one side of the heating element, 100 and back through the corresponding bridge 11 OB, to electrical connection 115B. The electrical resistance of wire electrical connectors 1 15 A, 1 15B is less than that of bridge member 1 10, so that transmitted power causes little to no internal heating, and the wires (in the cold-side outside of a furnace 7) face no degradation.

[0037] Please note that terminal ends or legs 102A, 102B may be solid or hollow in formation, and are conventionally between about ¼-inch to ¾ inch in outer diameter, but there is no limit and the size, and surface are may be adjusted to aid in electrical conductivity.

[0038] Regarding further assembly with bridge elements 101 A, 10 IB, and bridge 101 in total, and the assembly thereof: The“bridge” joins each side of the prefired“hot zone” section to two pre-fired“cold end” rods or tubes terminals. The ’’bridge” structures are electrically conductive and of sufficiently refractory to withstand the high temperature produced by the“hot zone” to at least about 1650°C or above. The finished joints are primarily a Silicon Carbide (SiC) material which has a lower resistivity than the spiraled“hot zone” SiC to avoid significant self-heating in the“bridge” section.

[0039] The “bridge” structures are joined using a carbonaceous resin paste mixture while all the components are placed in a position-mold. Pre-fired SiC ferrules are placed around each“cold end” rod for dimensional spacing and to provide mechanical support until the resin paste is thermally dried and fully cured. There is then a period of non-thermal setting or green drying before removing from the mold. Thereafter, during thermal curing the organic content of the resin paste largely converts to a Carbon body. The cemented heating element can then be carefully removed from its assembly fixture and prepared for “siliconizing” at >1410°C in an induction or other high temperature furnace. During this firing process at a high temperature, the pre-form-Carbon body is reacted with Silicon (Si) metal located nearby (in the area and same region) to create“bridge” bodies between SiC grains which are primarily composed of SiC with a minor free Si content. As a result of the amount of free-Si (free silicone) content and the easy electrical conductivity through free-Si, the bridge members 101 easily transmit electricity to the heating element without thermal degradation.

[0040] Alternatively, pre-forms composed of Carbon and SiC powders can be dry -pressed to near -net shapes and then joined to each side of the spiraled“hot zone” section..

[0041] Having described at least one of the preferred embodiments of the present invention with reference to the accompanying drawings, it will be apparent to those skills that the invention is not limited to those precise embodiments, and that various modifications and variations can be made in the presently disclosed system without departing from the scope or spirit of the invention. Thus, it is intended that the present disclosure cover modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents.

Claims

WHAT IS CLAIMED IS:

1. A heating element system, comprising:

an electrically conductive spiral helix heating element having a spiral hot end and an opposed cool ending having a first cool side and a second cool side; said electrically conductive spiral helix heating element having a first heating element electrical resistance;

an electrically conductive first bridge member chemically bonded to extending from said first cool side and away from said hot end;

an electrically conductive second bridge member chemically bonded to and extending from said second cool side and away from said hot end and said first bridge member;

each said first bridge and said second bridge having a second bridge electrical resistance;

said second bridge electrical resistance being less than said first heating element electrical resistance;

a first electric terminal extending from said first bridge member;

a second electric terminal extending from said second bridge member; each said first electrical terminal and said second electric terminal having a third electric terminal electrical resistance;

said third electrical terminal electrical resistance being the same as or less than said second bridge electrical resistance;

a first electrical connector joined to said first electrical terminal at a first receiving profile geometry;

a second electrical connector joined to said second electrical terminal at a second receiving profile geometry;

each said first electrical connector and said second electrical connector having a fourth electrical resistance; and

said fourth electrical resistance being the same as or less than said third electrical tenninal electrical resistance.

2. A method of assembling a heating element system, comprising the steps of:

providing an electrically conductive spiral helix heating element having a spiral hot end and an opposed cool ending having a first cool side and a second cool side;

said electrically conductive spiral helix heating element having a first heating element electrical resistance;

providing an electrically conductive first bridge member chemically bonded to extending from said first cool side and away from said hot end;

providing an electrically conductive second bridge member chemically bonded to and extending from said second cool side and away from said hot end and said first bridge member;

each said first bridge and said second bridge having a second bridge electrical resistance;

said second bridge electrical resistance being less than said first heating element electrical resistance;

providing a first electric terminal extending from said first bridge member; providing a second electric terminal extending from said second bridge member;

each said first electrical terminal and said second electric terminal having a third electric terminal electrical resistance;

said third electrical terminal electrical resistance being the same as or less than said second bridge electrical resistance;

providing a first electrical connector joined to said first electrical terminal at a first receiving profile geometry;

providing a second electrical connector joined to said second electrical terminal at a second receiving profile geometry;

each said first electrical connector and said second electrical connector having a fourth electrical resistance; and said fourth electrical resistance being the same as or less than said third electrical terminal electrical resistance.

3. A heating element assembly, comprising:

an electrically conductive spiral helix heating element having a spiral hot end and an opposed cool ending having a first cool side and a second cool side; said electrically conductive spiral helix heating element having a first heating element electrical resistance;

an electrically conductive first bridge member chemically bonded to extending from said first cool side and away from said hot end;

an electrically conductive second bridge member chemically bonded to and extending from said second cool side and away from said hot end and said first bridge member;

each said first bridge and said second bridge having a second bridge electrical resistance;

said second bridge electrical resistance being less than said first heating element electrical resistance;

a first electric terminal extending from said first bridge member;

a second electric terminal extending from said second bridge member; each said first electrical terminal and said second electric terminal having a third electric terminal electrical resistance;

said third electrical terminal electrical resistance being the same as or less than said second bridge electrical resistance;

a first electrical connector joined to said first electrical terminal at a first receiving profile geometry;

a second electrical connector joined to said second electrical terminal at a second receiving profile geometry;

each said first electrical connector and said second electrical connector having a fourth electrical resistance; and said fourth electrical resistance being the same as or less than said third electrical terminal electrical resistance.