MULTI PLANAR HEATER ELEMENT FOR USE IN A HIGH-SPEED OVEN INCORPORATING A NOVEL TENSIONING SYSTEM

Abstract

This disclosure relates to a multi-planar heater element for use in a high-speed oven with a new tensioning system. Disclosed subject matter includes a radiative heater for use in a high-speed oven formed from two or more planar heater elements stacked closely to form an effective single element and allowing for extended life through the minimization of concentrated eddy currents in both elements. The disclosure further includes structures to install and remove various planar heating elements without any external tools.

Claims

1-24. (canceled)

25. A high-speed oven comprising: a holder box that is configured to receive a removable heating element, wherein the heating element is configured to rapidly heat upon receipt of electrical current therethrough, the heating element being planar and extending from a first end portion to a second end portion, the holder box includes a first end portion that is configured to removably receive the first end portion of the heating element and a second end portion that is configured to removably receive the second end portion of the heating element, the holder box supports a clamp that is pivotably mounted upon a horizontal surface of a heater box, the clamp biased toward a position where a first end of the clamp contacts the horizontal surface of the heater box, and pivotable to a second position where the first end is spaced away from the horizontal surface of the heater box, the horizontal surface comprises a first peg that extends upwardly from the horizontal surface and is disposed proximate to a location where the clamp contacts the horizontal surface of the heater box, the holder box further comprises a carrier that is slidably mounted thereon and proximate to a second end of the holder box remote from a first end that supports the clamp, the carrier is biased toward a wall of the holder box defining the second end of the holder box and can be urged to slide away from wall and toward the clamp, the carrier supports a second peg thereon.

26. The high-speed oven of claim 25, further comprising a heating element that extends between first and second ends with a central portion therebetween, wherein the heating element comprises a first hole that can be received upon the first peg and a second hole that can be received upon the second peg such that the central portion extends between the first and second end portions of the holder box.

27. The high-speed oven of claim 26, wherein the heating element comprises two or more sheets of metal overlaid upon each other, wherein the first hole extends concentrically through all of the overlaid two or more sheets and the second hole extends concentrically through all of the overlaid two or more sheets.

28. The high-speed oven of claim 25, wherein the first peg is a plurality of first pegs that are spaced apart along the horizontal surface of the holder box and are positioned to each extend within corresponding first holes through the heating element, wherein at least one of the plurality of first pegs is formed with a different cross-sectional geometry than others of the first pegs, wherein a corresponding at least one of the first holes is formed with a cross-sectional geometry that is the same as the at least one of the plurality of first pegs with a different cross-sectional geometry.

29. The high-speed oven of claim 25, wherein the second peg comprises a top portion with a cross-sectional geometry that is larger than a second portion below the top portion, wherein the heating element comprises a second hole that can received upon the second peg, wherein the second hole includes a first portion with a diameter that is larger than a largest diameter of the top portion of the second peg, and a second portion with a diameter that is smaller than the largest diameter of the top portion but is larger than a diameter of the second portion of the second peg.

30. The high-speed oven of claim 26, wherein the heating element further comprises first and second fingers that are spaced apart from each other and both extend from the second end of the heating element, wherein the second end of the heating element provides an electrical connection between the first and second fingers, and wherein the first end of the heating element include a first end of the first finger and a first end of the second finger, wherein the first hole comprises a hole disposed upon the first end of the first finger and a hole disposed upon the first end of the second finger, wherein the first peg comprises two or more pegs disposed upon the horizontal surface that are aligned with the holes upon the first ends of the first and second fingers when the heating element is aligned upon holder box.

31. The high-speed oven of claim 30, wherein the clamp is first and second clamps disposed proximate to each other upon the horizontal surface, wherein the first clamp is arranged to make electrical contact with the first end of the first finger and the second clamp is arranged to independently make electrical contact with the first end of the second finger, wherein the first and second clamps are wired to make opposite electrical contact with the first and second fingers of the heating element.

32. The high-speed oven of claim 31, wherein the first clamp is arranged to make positive electrical contact with the first end of the first finger and the second clamp is arranged to make negative electrical contact with the first end of the second finger, wherein the electrical current flowing through the first and second clamps and the heating electrode is AC or DC current.

33. The high-speed oven of claim 25, wherein the carrier includes an operator that allows a user to urge the carrier away from the wall and toward the clamp.

34. The high-speed oven of claim 25, wherein the holder box is configured to allow the heating element to be installed and removed therefrom without any tools.

35. The high-speed oven of claim 25, wherein when a heating element extends between the first and second end portions of the holder box and is connected to the first and second pegs, the carrier slides with respect to the holder box when the heating element expands or contracts due to a change in temperature of the heating element, which maintains the heating element in tension within the holder box.

36. The high-speed oven of claim 27, wherein the two or more sheets of metal comprise a mesh or lattice structure along the central portion of the heating element.

37. The high-speed oven of claim 27, wherein the two or more sheets comprise at least two different thicknesses.

38. The high-speed oven of claim 27, wherein each of the two or more sheets comprise a planar section, and a thickness of each of the planar sections is greater than 0.001 inches.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0032] The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and together with the description serve to explain the principles of the invention.

[0033] FIG. 1 is an isometric view of a flat mesh heating element made from a single flat sheet and foldable so as to create two parallel planar sections for carrying a high current further spaced together so as to induce mutual magnetic fields during use that distribute the current evenly and allow for cycling above 15,000 times.

[0034] FIG. 2 is an isometric view of the heating element in FIG. 1 folded so as to create a multi-planar element.

[0035] FIG. 3 is an isometric view of the heating element of FIGS. 1 and 2 folded completely to form a multi-planar heating element.

[0036] FIG. 4 is an isometric closeup view of the connection paths of the union section of the multi-planar heating element of FIGS. 1, 2, and 3.

[0037] FIG. 5 is an isometric view of a tensioning system used to hold the mesh of FIGS. 1-3.

[0038] FIG. 5a is a perspective view of a set of holder boxes without elements secured thereto.

[0039] FIG. 5b is another perspective view of the holder boxes of FIG. 5a with an element installed thereon, with the user rotating one clamp to allow one side of the element to be removed with the other clamp engaging the other side of the element.

[0040] FIG. 5c is a top view of an element for use with the holder box of FIGS. 5a and 5b.

[0041] FIG. 5d is a perspective view of a holder box showing the opposite end of the element engaged with a carrier.

[0042] FIG. 5e is another perspective view of the holder box of FIG. 5d showing the end of the element bent away from the carrier and the user pressing the carrier away from the side wall of the holder box.

[0043] FIG. 5f is another perspective view of the holder box of FIG. 5d with the end of the element not attached to the carrier and the carrier not pressed away from the side wall of the holder box.

[0044] FIG. 5g is a detailed perspective view of the carrier that is slidably attached to the holder box of FIG. 5d.

[0045] FIG. 5h is a view of detail AA of FIG. 5c.

[0046] FIG. 5i is a view of an alternate hole that may be provided upon the element to allow for the element to only be installed upon the frame in one direction and orientation.

[0047] FIGS. 6a and 6b are isometric views of a roll of sequentially formed elements such as that in FIG. 1c so as to create a continuous string of elements.

[0048] FIG. 7 is an isometric view of the manufacturing process used to make the element of FIGS. 1-6 further including a coating process.

[0049] FIG. 8 is a diagram illustrating the relative placement of the multi-planar heating element on a plot of the life during cycling versus the wattage and further compared to past developed heating elements with DER values less than 2 for use in high speed ovens.

[0050] Throughout the drawings and the detailed description, unless otherwise described, the same drawing reference numerals will be understood to refer to the same elements, features, and structures. The relative size and depiction of these elements may be exaggerated for clarity, illustration, and convenience.

DESCRIPTION

[0051] The present teachings disclose a novel heating element having a DER of less than 2 ohms/m2 an ability to be powered at over 1500 watts, capable of increasing repeatedly in temperature at a rate of at least 100 degree C. per second, and be capable of being cycled more than 15,000 times on and off every 5 seconds. The following details the specifications of two such bi-layer elements and the cycling life achieved when cycled 5 seconds on/5 seconds off. As can be seen from the table, the first element cycled over 74,378 times before complete failure and the second cycled over 50,000 times.

TABLE-US-00009 0.004 K-Diamond Cut 50% Bi Metal W/Cut Even 0.015″ Back Max Life Cycles 74378 cycles Voltage 20.80 volts Single Element Resistance 0.17 ohms Single Element Watts 2496 watts Single Element Radiative Area 0.05 m2 Extrapolated Element Radiative Area for 0.21 m2 0.25 m × 0.25 m oven Extrapolated Resistance Radiative Area 0.02 ohm for 0.25 m × 0.25 m oven DER 0.1 ohm/m2 Extrapolated Power/DER Ratio 98106 watts-m2/ohm 0.004 K-Diamond 50% Bi Metal W/Filled Even 0.015″ Back Max Life Cycles 50000+ cycles Voltage 23.20 volts Single Element Resistance 0.19 ohms Single Element Watts 2853 watts Single Element Radiative Area 0.05 m2 Extrapolated Element Radiative Area for 0.21 m2 0.25 m × 0.25 m oven Extrapolated Resistance Radiative Area 0.02 ohm for 0.25 m × 0.25 m oven DER 0.11 ohm/m2 Extrapolated Power/DER Ratio 103072 watts-m2/ohm

[0052] FIG. 1a is an isometric view of the novel heating element 1 in a preferred embodiment formed from a single sheet of heating material 2. These materials include Kanthal alloys, stainless steel alloys, nickel chromium alloys, and other ferrous and non-ferrous metals used for heating elements. Mesh areas 4 and 24 formed through etching, stamping, or other machine process on both halves 3 and 5 along centerline 6 such that the resistance of the element is matched with the driving voltage and current required. In some cases, mesh areas 4 and 24 may be solid, thinned, cut, and otherwise modified. Heating element 1 having a DER of less than 2 ohms/m2 an appropriate resistance which may be less than 2 ohms. Halves 3 and 5 having union ends 7 and 8 respectively and formed with equal resistive paths 9 to mitigate the formation of hot spots during operation in areas 10, 11, 12, and 13. In some cases meshed areas 14 and 15 further thinned down in thickness compared to ends 16 and 17 and union areas 7 and 8 such that the regions can be heated quickly to an optimum wavelength for radiative cooking. As an example, meshed areas 14 and 15 may have a thickness of 0.002″-0.015″ while union ends 16 and 17 may be 0.015″-0.100″ thick.

[0053] In FIG. 2, halves 3 and 5 are folded along centerline 6 so as to mate union ends 7 and 8, ends 17 and 18, and meshed areas 4 and 24 as well as the tensioning holes 18, 21, and 19 on half 5 to the corresponding holes on half 3.

[0054] FIG. 3 illustrates element 1 now completely folded at centerline 6 to form element 30 with edges 40, 41, and 42 and mated areas 3 and 5. In some cases, welding the two halves 3 and 5 in regions 31, 32, 33, and/or 34 may help to insure proper current distribution when the element is powered from ends 16 and 17.

[0055] In one preferable embodiment, the stepped down at 45, 46, 47, and 48 of FIGS. 3 and 4 allows for a flat surface for mating in region 5 between halves 3 and 5. The closer mating of the surfaces allowing for the induced magnetic fields during operation to affect the current flow to thereby avoid current concentrations.

[0056] FIG. 5 illustrates a holding box 800 for element 1 and 30 with springs 71 attached to the mated union ends 7 and 8 through holes 19. Secondary conductor bars (as further described in co-pending provisional application “Stepped Heater Element for Use in A High Speed Oven”) 72 and 73 carry a voltage potential that passes electrical current through the two “legs” 74 and 75 of area 3 and 5 of element 1 and 30 through ends 16 and 17. The electrical current may be of various forms, including dc or ac, stepped, triangular, square waves, pulse modulated, or in multiple phases. The holding box which may become part of an oven further including a reflective surface 80 and side walls 81. Monitoring the temperature of said surface or surfaces 80 may be done when they are formed into an oven cavity which may itself be monitored. A predetermined cycle or continuously adjusted cycling based on input to the control system from a sensor and operation of the element may be performed to control the output wavelengths of the heater to optimize performance in an application such as cooking, baking, searing, curing, or other heating. The heater may also be submerged in liquids for heating.

[0057] In order to place element 1 within in holder box 800 so as to secure a simultaneous electrical voltage application and a mechanical tensioning, the element ends 302 and 301 are placed under secondary conductor bars (or clamps) 73 and 72 respectively. The secondary conductor bars 73, 72 may be biased to a position where they engage the element ends 16, 17 when provided therein, and when not provided the clamps 73, 72 engage a horizontal surface of the holding box 800. Clamps 73, 72 may be each further connected to the positive and negative electrical circuit that powers the element 1. These clamps 73, 72 may have a positive actuation locking mechanism, a spring forcing mechanism, or any other mechanism intended to provide positive connection and pressure to insure a proper electrical connection. Engagement portions of the clamps 73 and 72 may be nickel plated so as to prevent wear and insure a strong electrical contact with minimal resistance. In some embodiments, each of clamps 73, 72 include a peg that is configured to extend within the corresponding tensioning hole that is provided at the respective end 16, 17 of the element to result in mechanical and electrical connection between the clamps 73, 72 and the element 1.

[0058] In an embodiment depicted in FIGS. 5a-5c, a horizontal surface 810 of the holding box 800 may include alignment pegs 819a that extend upwardly therefrom, which are positioned to allow corresponding holes 19a upon ends of the element to receive the alignment pegs 819a. In some embodiments each of the ends 16, 17 may include a single hole 19a, while in other embodiments, each end 16, 17 includes two or more holes 19a. The clamps 73, 72 are biased (such as with springs 311 as depicted in FIG. 5b) to contact a surface of the respective end 16, 17 of the element 1 that is aligned with respective clamp 73, 72 (such as regions 1031 and 1032 depicted in FIG. 5c) and the clamps 73, 72 are biased to contact and compress the respective end 16, 17 upon the horizontal surface 810 of the holding box 800 to mechanically fix the ends 16, 17 to the holding box. As with the embodiment discussed above, the clamps are connected to the positive and negative electrical circuit that powers the element 1. In some embodiments, the clamps 73, 72 may include operators 73a, 72a that allow for user to operate to lift the respective clamp 73, 72 away from contact with the aligned end 16, 17 to allow an element to be removed, and similarly to lift the clamp 73, 72 away from the horizontal surface 810 to allow an element to be attached (via the alignment pegs 819a). FIG. 5b depicts clamp 73 lifted away from contact with the end 16 of the element by the user pressing upon the operator 73a and clamp 72 in contact with end 17 of the element 1.

[0059] In another embodiment depicted in FIGS. 5d-5f (with may be used with the embodiment of FIGS. 5a-5c or another embodiment to secure the opposite end of the element 1), folded ends 7, 8 of the element 1 may be received within the holding box 800 with a spring loaded connection. The folded ends 7, 8 of the element 1 may include hole 19z (as in the figures) or a plurality of holes such as holes 19w depicted in FIG. 5c that receive a peg 419 (or pegs for multiple holes) that extends from a carrier 410 that slides along the holding box 800. The carrier 410 may include a horizontal surface 411 from which the peg 419 extends and a biasing surface 412, which may extend perpendicularly upward from the horizontal surface such that is parallel to a side wall 830 of the holding box 800. The biasing surface 412, and therefore the entire carrier 410 is biased toward the side wall 830 with one or more springs 431 that are supported by shafts 430. An operator 420 may be connected to the biasing surface 412 and be capable of being manipulated by the user to slide the carrier 410 against the biasing force of the springs 431. In FIG. 5e, the user has pressed the operator 420 such that the carrier 410 is slid away from the side wall 830 and the user has bent the element 1 to allow for establishing alignment between the hole 19z and the peg 419. In FIG. 5f, the carrier is shown in the normal position with the peg 419 not extending within the hole. In FIG. 5d the peg 419 extends within the hole 19z. As can be understood by one of ordinary skill in the art with a review and understanding of this disclosure, the springs 431 maintain a tension on the element 1 (with the opposite side of the element disposed upon their respective pegs 819 and engaged with the clamps 73, 72) as the size of the element 1 changes as the element is heated and cooled during use, when the element 1 heats up and expands the springs 431 urge the biasing surface 412 and therefore the carrier 410 closer to the side wall 830 and as the element cools down and therefore contracts the springs 431 are pulled to allow the biasing surface 412 and therefore the carrier 410 further from the side wall 830.

[0060] In some embodiments, the hole 19z may be a round hole, while in other embodiments, as best shown in FIGS. 5g and 5h, the hole 19z may be a teardrop or keyhole shape, with a first portion 19e that includes a first diameter Z that is larger (such as 20-50% larger) than a diameter (such as a largest diameter as discussed below) of the peg 419 and a second portion 19f with a diameter Y that is smaller than a diameter of the peg 419. The term diameter as used herein may apply to portions of the hole that include a curvature that is greater than half of a circle as well as to the curvature that if completed in a full circle, or greater than half of a circle would form a diameter. In some embodiments, the diameter of the peg 419 at the top end 419a may be larger than the second diameter Y with the peg including a lower portion 419y (below the top end) that has a diameter that is less than the second diameter Y such that the lower portion 419y of the peg extends through the second portion 19f of the hole 19z with the second diameter Y when the element is disposed upon the peg 419, while when in this configuration the element 1 cannot be lifted above the peg 419 due to interference between the second portion 19f of the hole and the top portion 419a of the peg. The first diameter Z of the hole 19z is provided to provide for play between the peg 419 and the hole 19z to allow the peg to be easily inserted within the hole 19z by the user.

[0061] In some embodiments, the end 7 of the element may include two or more holes 19w, which may be round holes or shaped as in the hole depicted in FIG. 5g and described above.

[0062] In some embodiments, the pegs 819a and the respective holes 19a that engage the pegs 819a may be provided to ensure that the element 1 can only fit onto the pegs 819a in one specific orientation, such as to avoid installing the element 1 upside down or backwards. For example, as depicted in FIG. 5i, in some embodiments, one of the two holes 19c upon the element may be may be square, triangular, or another geometric or arbitrary shape, or round with a different diameter than the other hole 19a, with a correspondingly shaped peg 819a disposed upon the frame 900. The other hole 19a/peg 819a disposed upon the same side of the element may be round or a different shape. Accordingly, the user can only install the element in one orientation and have the holes 19a/19c fit around the pegs 819a disposed upon the holder box 800.

[0063] The embodiments described above and depicted in FIGS. 5a-5f are specifically depicted with respect to a folded element 1 that is described within this patent application, one of ordinary skill in the art will readily comprehend with a thorough review of this specification and figures that the embodiments of FIGS. 5a-5f can be readily used for a single layer element or elements with more than two layers, and also for an element with only a single leg (thereby only needing one clamp 73) or with more than two legs (thereby needing the same number of clamps as legs).

[0064] One of the observations made of the novel bi-element is the reduction of the magnetic field in areas 300, 400, 301, and 302 in direction 401. In one trial, a single layer region was used for the union area 7 testing in the holding fixture 800 of FIG. 5 and it was found that the magnetic field at 300 and 400 in direction 401 was reduced from about 39 gauss to 9.5 gauss (at 0.1 meters).

[0065] While it is difficult to fully characterize the eddy currents induced in the multiple layer heating element, the change of the magnetic field versus a single element and the presumed associated redirection of the electrical current can be considered a significant factor for the increased life.

[0066] FIG. 6a illustrates a continuous roll 90 of elements 1 and 30 joined sequentially to form a roll with the potential of being operated many millions of cycles. US patent application U.S. Ser. No. 15/183,967 describes a continuous mesh system yet does not describe integrated primary and secondary conductor bars. Co-pending provisional application “Stepped Heater Element for Use in A High Speed Oven” describes primary conductors that are integrated within the continuous mesh yet does not include the two or more layers that form the primary mesh or a post folding process to create a bi-element as herein described per this invention. FIG. 6b is an alternative roll form being a single layer having elements 1 and 30 of FIGS. 1 through 5 formed sequentially but then folded manually or in an automated fashion at the time of use.

[0067] The process of manufacturing a roll 90 such as that in FIGS. 6a and 6b is further shown in FIG. 7. The process for making the two halves of element 1 and 30 through etching, stamping, pressing or thinning, or other machine process from blank roll stocks 100 and 101 is done within system or systems 590 and secondary process such as coating done at 591. A single roll 100 may also be used and rather than folding the element 1 per FIGS. 1, 2, and 3, two parallel single sheets may be formed along edge 107 of FIG. 3 and then folded along the edge to create element 30. Other symmetrical folding or manufacturing processes may be employed to create an element with multiple layers per the specifications of this patent and further each of these elements may be parted singularly or in multiples before, during, or after use.

[0068] FIG. 8 is a diagram illustrating the relative placement of the multi-planar heating element on a plot of the life during cycling versus the wattage and further compared to past developed heating elements with DER values less than 2 for use in high speed ovens. As can be noted from the graph, the multi-planar elements provide very significant benefit.

[0069] The examples presented herein are intended to illustrate potential and specific implementations. It can be appreciated that the examples are intended primarily for purposes of illustration for those skilled in the art. The diagrams depicted herein are provided by way of example. There can be variations to these diagrams or the operations described herein without departing from the spirit of the invention. For instance, in certain cases, method steps or operations can be performed in differing order, or operations can be added, deleted or modified.