Honeycomb heater body

Abstract

An electric heater body is disclosed that includes an outer periphery, a plurality of slots, a plurality of core segments, and a plurality of end regions. Each slot extends from the outer periphery to an end within the electric heater body. Each core segment is defined between a different pair of adjacent slots. Each end region is between one of the ends of the slot and the outer periphery. Each pair of adjacent core segments is connected by one of the end regions. The electric heater body is shaped as an array of intersecting walls. A first set of intersecting walls extends in a main direction parallel to the plurality of slots. A second set of intersecting walls intersects the first set at a plurality of intersection angles. At least a portion of the intersection angle in each of the core segments varies along the main direction.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority benefit under 35 U.S.C. §119 to U.S. Provisional Application No. 63 / 439,693, filed on January 18, 2023, the contents of which are relied upon and incorporated herein by reference in their entirety. Technical Field

[0003] The present disclosure relates to heater assemblies including a honeycomb body, particularly a honeycomb body having a serpentine flow-carrying path defined by slots extending into the honeycomb body, and to exhaust aftertreatment systems including such heater assemblies. Background Art

[0004] Pollution abatement systems, such as exhaust aftertreatment systems coupled to internal combustion engines (e.g., those of automobiles or other vehicles), may include heater assemblies to provide supplemental heat to assist in the operation of the system. For example, catalyst materials used in catalytic converters or other catalyst-containing aftertreatment components may require a sufficient minimum temperature to initiate the catalytic reaction, which may be referred to as catalyst light-off.

[0005] In the case of an internal combustion engine, heat can also be supplied from the exhaust gas flow itself, but each time the engine is first started, it can take some time for the exhaust gas temperature to fully rise, which can be referred to as a cold start of the engine. Even if the system is arranged so that the exhaust gas flow heats the catalyst to its light-off temperature within a few seconds, these first few seconds after a cold start can significantly contribute to the engine's overall emissions and may even constitute a significant portion of the engine's emissions. Therefore, the supplemental heat provided by the heater assembly can significantly reduce the time it takes to reach the catalyst's light-off temperature, thereby reducing emissions, particularly after a cold start event. Summary of the Invention

[0006] In general, in one aspect, an electric heater body is disclosed. The electric heater body includes an outer periphery.

[0007] The electric heater body further comprises a plurality of slots, each slot extending from the outer periphery to a terminal end within the electric heater body.

[0008] The electric heater body further includes a plurality of core segments. The plurality of core segments include a conductive material. Each core segment is defined between a different pair of adjacent slots. The conductive material is shaped into an array of intersecting walls defining a honeycomb cell pattern.

[0009] The electric heater body further includes a plurality of end regions. The plurality of end regions include the conductive material. Each end region is located between a corresponding one of the ends of the slot and the outer periphery. Each pair of adjacent core segments is connected by a corresponding one of the plurality of end regions.

[0010] The plurality of slots disconnect each pair of adjacent core segments from each other to form a conductive meandering path. A first set of the array of intersecting walls extends in a primary direction parallel to the plurality of slots. A second set of the array of intersecting walls intersects the first set of walls at a plurality of intersection angles. At least a portion of the plurality of intersection angles in each of the plurality of core segments varies along the primary direction.

[0011] In an embodiment, each of the plurality of core segments includes a square unit portion. Each of the plurality of intersection angles within the square unit portion is substantially ninety degrees. Each of the plurality of core segments further includes a first skewed unit portion connecting the square unit portion to one of the plurality of end regions. Each of the plurality of intersection angles within the first skewed unit portion is greater than ninety degrees. Each of the plurality of core segments further includes a second skewed unit portion connecting the square unit portion to another of the plurality of end regions. Each of the plurality of intersection angles within the second skewed unit portion is greater than ninety degrees.

[0012] In one embodiment, within the first skewed unit portion, the plurality of intersection angles gradually increase in size along the main direction from the square unit portion toward the first end region. In another embodiment, within the second skewed unit portion, the plurality of intersection angles gradually decrease in size along the main direction from the second end region toward the square unit portion.

[0013] In an embodiment, each core segment in the plurality of core segments has an equal skew ratio. The skew ratio of a core segment in the plurality of core segments can be defined as the ratio of the number of cells in the first skewed cell portion and the second skewed cell portion to the number of cells in the square cell portion. In another embodiment, each core segment in the plurality of core segments has a skew ratio of approximately 15 percent.

[0014] In an embodiment, a portion of the honeycomb cell pattern within the plurality of end regions is substantially trapezoidal.

[0015] In an embodiment, the conductive material is a metal, a metal alloy or a metal composite. In another embodiment, the conductive material is a nickel-chromium based superalloy.

[0016] In an embodiment, the electric heater body is formed via additive manufacturing or extrusion.

[0017] In an embodiment, the end of each slot of the plurality of slots is rounded.

[0018] In an embodiment, an electric heater assembly is provided. The electric heater assembly includes an electric heater body. The electric heater body is coupled to a pair of electrodes at opposite ends of a conductive serpentine path.

[0019] In general, in another aspect, an electric heater body is disclosed. The electric heater body includes an outer periphery.

[0020] The electric heater body further comprises a plurality of slots, each slot extending from the outer periphery to a terminal end within the electric heater body.

[0021] The electric heater body further includes a plurality of core segments. The plurality of core segments include a conductive material. Each core segment is defined between a different pair of adjacent slots. The conductive material is shaped into an array of intersecting walls defining a honeycomb cell pattern.

[0022] The electric heater body further includes a plurality of end regions. The plurality of end regions include the conductive material. Each end region is located between a corresponding one of the ends of the slot and the outer periphery. Each pair of adjacent core segments is connected by a corresponding one of the plurality of end regions.

[0023] The plurality of slots disconnect each pair of adjacent core segments from each other to form a conductive meandering path.The cross-sectional area of at least a portion of the honeycomb cell pattern varies along a main direction parallel to the plurality of slots.

[0024] In an embodiment, each of the plurality of core segments includes a square cell portion. The square cross-sectional area of each cell in the honeycomb cell pattern within the square cell portion is substantially equal. Each of the plurality of core segments further includes a first skewed cell portion connecting the square cell portion to a first end region of the plurality of end regions. The first skewed cross-sectional area of each cell in the honeycomb cell pattern within the first skewed cell portion is greater than the square cross-sectional area. Each of the plurality of core segments further includes a second skewed cell portion connecting the square cell portion to a second end region of the plurality of end regions. The second skewed cross-sectional area of each cell in the honeycomb cell pattern within the first skewed cell portion is greater than the square cross-sectional area.

[0025] In an embodiment, within the first skewed cell portion, the cross-sectional area of each cell gradually increases along the main direction from the square cell portion toward the first end region. In another embodiment, within the second skewed cell portion, the cross-sectional area of each cell gradually decreases along the main direction from the second end region toward the square cell portion.

[0026] In an embodiment, the end of each slot of the plurality of slots is rounded.

[0027] In an embodiment, each core segment of the plurality of core segments has an equal skew ratio.

[0028] In general, in another aspect, an electric heater body is disclosed. The electric heater body includes an outer periphery.

[0029] The electric heater body further comprises a plurality of slots, each slot extending from the outer periphery to a terminal end within the electric heater body.

[0030] The electric heater body further includes a plurality of core segments. The plurality of core segments include a conductive material. Each core segment is defined between a different pair of adjacent slots. The conductive material is shaped into an array of intersecting walls defining a honeycomb cell pattern.

[0031] The electric heater body further includes a plurality of end regions. The plurality of end regions include the conductive material. Each end region is located between a corresponding one of the ends of the slot and the outer periphery. Each pair of adjacent core segments is connected by a corresponding one of the plurality of end regions.

[0032] The plurality of slots disconnect each pair of adjacent core segments from each other to form a conductive meandering path. A first set of the array of intersecting walls extends in a primary direction parallel to the plurality of slots. A second set of the array of intersecting walls intersects the first set of walls at a plurality of intersection angles. Each of the plurality of conductive paths defined as from the first set of the array of intersecting walls to one of the slots gradually changes in conductance along the primary direction.

[0033] It should be understood that both the foregoing general description and the following detailed description are exemplary only and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding and are incorporated into and constitute a part of this specification. The drawings illustrate one or more embodiments and, together with the description, serve to explain the principles and operation of the various embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a cross-sectional side view of an exhaust aftertreatment assembly according to embodiments disclosed herein.

[0035] Figure 2 is a front view of an electric heater assembly having a serpentine design formed by a plurality of electrically insulating slots, a plurality of core segments between each pair of adjacent slots, and end regions proximate the ends of each slot and connecting adjacent core segments together, according to an embodiment disclosed herein.

[0036] Figure 3 A portion of a heater body is shown according to embodiments disclosed herein.

[0037] Figure 4is a front view of a portion of a heater body having a square cell design according to embodiments disclosed herein.

[0038] Figure 5 is a front view of a portion of a heater body having a skewed cell design according to embodiments disclosed herein.

[0039] Figure 6 is a front view of a portion of a heater body having a skewed cell design according to embodiments disclosed herein, showing intersection angles and conductive paths formed by an array of intersecting walls.

[0040] Figure 7 is a front view of a portion of a heater body having a skewed cell design and rounded slot ends according to embodiments disclosed herein.

[0041] Figure 8A is a power density model illustrating a cold zone in a portion of a heater body having a square cell design according to embodiments disclosed herein.

[0042] Figure 8B is a power density model showing a warmer zone in a portion of a heater body having a skewed cell design according to embodiments disclosed herein.

[0043] Figure 9A is a peak power consumption model according to embodiments disclosed herein that focuses on the slot end adjacent portion of the vertical wall of a heater body having a square unit design.

[0044] Figure 9B is a peak power consumption model according to embodiments disclosed herein that focuses on the slot end adjacent portion of the vertical wall of a heater body having a skewed cell design.

[0045] Figure 10A is a front view of a model of a heater body according to embodiments disclosed herein.

[0046] Figure 10B According to the embodiments disclosed herein Figure 10A Temperature profile of the heater body.

[0047] Figure 11A is a front view of a model of a heater body according to embodiments disclosed herein, wherein each core segment has an equal skew ratio.

[0048] Figure 11B According to the embodiments disclosed herein Figure 11A Temperature profile of the heater body.

[0049] Figure 12is a front view of a mock-up of a heater body having a square cell design and multiple V-shaped features for hot spot relief according to embodiments disclosed herein.

[0050] Figure 13 is a graph comparing the temperature over time of two heater bodies having square and skewed designs, respectively, according to embodiments disclosed herein.

[0051] Figure 14 is a graph comparing the gas temperature uniformity factor over time for two heater bodies having square and skewed designs, respectively, according to embodiments disclosed herein.

[0052] Figure 15A According to the embodiment disclosed in this article, Figure 12 The gas temperature distribution profile of the heater body is shown in FIG.

[0053] Figure 15B According to the embodiment disclosed in this article, Figure 11B The gas temperature distribution profile of the heater body is shown. DETAILED DESCRIPTION

[0054] Reference will now be made in detail to the exemplary embodiments shown in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings to refer to the same or similar parts. The components in the drawings are not necessarily drawn to scale, but rather emphasis is placed upon illustrating the principles of the exemplary embodiments.

[0055] Numerical values, including the endpoints of a range, may be expressed herein as approximate values preceded by the terms "about," "approximately," etc. In such cases, other embodiments include the specific value. Regardless of whether a value is expressed as an approximation, two embodiments are encompassed in this disclosure: one expressed as an approximation and the other not. It will also be understood that the endpoints of each range are significant both relative to the other endpoint and independently of the other endpoint.

[0056] Modifications to the present disclosure may be made by those skilled in the art and by those skilled in the art of making or using the present disclosure. Therefore, it should be understood that the embodiments shown in the drawings and described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure, which is defined by the appended claims interpreted in accordance with the principles of patent law including the doctrine of equivalents.

[0057] As used herein, the term "about" means that amounts, sizes, formulations, parameters and other quantities and characteristics are not and need not be exact, but may be approximate and / or larger or smaller as necessary, reflecting tolerances, conversion factors, rounding, measurement errors, etc. and other factors known to those skilled in the art. When the term "about" is used to describe a value or a range end-point, it should be understood that the disclosure also encompasses the specific value or end-point mentioned.

[0058] As used herein, directional terms such as up, down, right, left, front, back, top, and bottom are made with reference only to the drawings as drawn and are not intended to imply an absolute orientation. As used herein, the term "radial" refers to a direction perpendicular to an indicated axial direction, which is from a center point of a shape (e.g., see FIG. Figure 2 The central axis C in the figure extends to or toward the outer periphery of the shape, regardless of the shape of the component or feature relative to which the radial direction is used. Similarly, the term "diameter" as used herein is not limited to circular shapes, but refers to the longest dimension of a component passing through the center point (center axis) of the shape of the component. For example, the radial distance of a square component can be measured as the straight-line distance from the center point (center axis) to the intersection with one wall of the square, and the diameter of the square refers to the longest dimension diagonally across the square. The terms "cross-sectional width" or "cross-sectional dimension" may also be used to refer to these directions perpendicular to the axial direction.

[0059] Fluid treatment systems, such as automotive exhaust aftertreatment systems or other pollution reduction systems, may include a supplemental heat source to facilitate operation, such as faster catalyst light-off in the case of catalyst-containing systems. For example, heat may be supplied by an electric heater (e.g., arranged to transfer heat to the catalyst material) or an electrically heated catalyst substrate (e.g., a conductive substrate carrying the catalytic material). For example, the heater may be arranged upstream of the catalyst substrate and heat the catalyst by providing heat to the exhaust gas flow (or supplemental air flow), which in turn heats the catalyst. An aftertreatment system employing supplemental heat may be provided to reduce emissions in gasoline, diesel, and / or hybrid vehicles to help ensure rapid and consistent catalyst light-off during operation of the corresponding engine, particularly after a cold start of the engine.

[0060] Now refer to Figure 1 , shows a fluid treatment assembly 10 that can be arranged as part of an exhaust system of an automobile, for example. The fluid treatment assembly 10 includes an outer housing 12 (which may alternatively be referred to as a "can") formed, for example, from metal or a suitable material into a generally tubular shape (e.g., a hollow tube). The outer housing 12 has an inlet 14 that can be connected in fluid communication with an exhaust manifold of an internal combustion engine, for example, and an outlet 16 that can be connected in fluid communication with a tailpipe of the automobile, for example.

[0061] Exhaust gas or other fluid stream from an engine (the fluid stream to be treated is generally referred to herein as "exhaust gas") may be treated (e.g., to remove or reduce one or more pollutants) as the exhaust gas flows through the assembly 10 from the inlet 14 to the outlet 16. To this end, the assembly 10 further includes a heater assembly 18 and an after-treatment component 20 located between the inlet 14 and the outlet 16. For example, the after-treatment component 20 may be a catalyst-loaded substrate, a particulate filter, or a catalyst-loaded particulate filter. For example, the catalyst substrate and the particulate filter may include a porous ceramic honeycomb body having an array of walls that form a plurality of fluid flow paths or channels extending axially (in the direction of exhaust gas flow and / or perpendicular to the end face of the body) through the body.

[0062] As described in more detail herein, the heater assembly 18 can be a resistive heater that provides supplemental heat to facilitate the function of the after-treatment component 20, for example, by rapidly initiating ignition of a catalytic material disposed in or on the walls of the heater assembly 18 and / or the after-treatment component 20. For example, the heater assembly 18 can include or be otherwise connected to an electrode 22. The electrode 22 can be arranged to extend through the housing 12 to connect the heater assembly 18 to a power source, such as a vehicle battery. Figure 1 As shown in FIG, the electrodes 22 may extend radially through the housing 12. However, the electrodes 22 may alternatively extend axially through the housing 12, and / or one electrode may extend radially while the other electrode extends axially. In this manner, the heater assembly 18 may be arranged to generate heat via Joule heating when the heater assembly 18 is connected to a power source and a corresponding voltage is applied to cause current to flow through the walls of the heater assembly 18. The electrodes 22 may extend axially through the housing 12. Figure 1 18 (eg, spaced 180° relative to the exterior of the heater assembly 18), but may be arranged at other locations or angles.

[0063] In the embodiments disclosed herein, for example Figure 1 As shown in FIG, heater assembly 18 is positioned upstream of after-treatment component 20 (relative to the direction of exhaust gas flow) to increase the temperature of the exhaust gas flow and / or provide direct heating to after-treatment component 20. This, in turn, increases the temperature of after-treatment component 20, such as the temperature of the catalytic material carried by after-treatment component 20, as the exhaust gas flows through after-treatment component 20. In some embodiments, heater assembly 18 and after-treatment component 20 can be effectively combined into a single device by directly supporting the catalyst with the body of heater assembly 18. Such an arrangement that can be used to heat the catalyst material may be referred to as an electrically heated catalyst, or EHC.

[0064] A vehicle exhaust system may be formed by connecting additional lengths of tubing (not shown) to assembly 10 at inlet 14 (e.g., extending between inlet 14 and the engine exhaust manifold) and outlet 16 (e.g., extending from outlet 16 to the tailpipe). Depending on how the design or configuration of the exhaust system varies from vehicle to vehicle, various components and / or lengths of tubing may have different diameters at different locations along the flow path through the exhaust system.

[0065] The heater assembly 18 and after-treatment component 20 can be held in place, supported, and / or contained within the housing 12 in any suitable manner. For example, the body of the heater assembly 18 can be held in place and supported via one or more retainers 24, such as retaining rings. The after-treatment component 20 can be supported by similar retainers and / or by a mat 26, such as an inorganic fiber mat, which helps protect the after-treatment component from, for example, vibration or thermal expansion forces exerted on the after-treatment component 20 during operation.

[0066] Now refer to Figure 2-3 , showing one embodiment of the heater assembly 18. Consistent with the disclosure herein, the embodiments shown and / or described herein may be used as or incorporated into the heater assembly 18 in the assembly 10, and combinations of features of the embodiments shown or described herein may be used together in the heater assembly 18 in the assembly 10.

[0067] As further described herein, the heater assembly 18 includes a heater body 30 constructed of a conductive material having a pair of electrodes (e.g., Figure 2-3 The heater body 30 extends along a serpentine current carrying path (or simply referred to as a "serpentine path") between the electrodes 22 (not shown). A portion of the serpentine path of the heater body 30 is located at Figure 2 3. The serpentine path 32 of the body 30 is identified by a dashed line and reference numeral 32. As further described herein, the serpentine path 32 of the body 30 is created by a plurality of slots 34 extending into the body 30 from a periphery 36 of the body 30.

[0068] Current flow along the serpentine path 32 of the heater body 30 (eg, honeycomb body) may be via, for example, electrodes 22 at opposite ends of the serpentine path 32 (see FIG. Figure 1 , Figure 2The electrodes 22 or portions thereof may be integrally formed with the heater body 30 or separately attached, for example, at corresponding electrode attachment points 38, such as via mechanical fastening or welding. In this manner, electrical connections may be established along the serpentine path 32 through the body 30 via electrodes secured at opposing ends. For example, properties of the honeycomb body 30, such as the dimensions of the honeycomb body 30, the length of the serpentine path 32, the area of conductive material of the heater body 30 available for current flow per unit length along the serpentine path 32, and / or the resistivity of the material of the honeycomb body 30, may be configured relative to a target or selected voltage intended to be applied to the electrodes 22 so as to generate heat via resistive heating when current passes through the material of the heater body 30.

[0069] In an embodiment, heater body 30 is arranged relative to a selected voltage (e.g., the voltage available to heater assembly 18 from the vehicle battery) to achieve a temperature suitable for catalyst light-off, for example, between approximately 700°C and 1000°C, although other temperatures may be targeted based on the application of heater assembly 18 and / or the thermomechanical properties of the material selected for heater body 30. In an embodiment, the material of heater body 30 comprises a metal, a metal alloy, or a metal composite. For example, various metal alloys are particularly advantageous for use in resistive heating elements due to their thermomechanical, environmental resistance, and electrical properties. In an embodiment, the metal comprises an alloy comprising one or more of nickel, chromium, iron, and / or aluminum, such as a nickel-chromium alloy or an iron-chromium-aluminum alloy, although other materials suitable for or used as resistive heaters may also be used. However, because these materials comprise metals, they typically have relatively high electrical conductivity. Advantageously, the serpentine design described herein allows the current-carrying path length of the heater body to be many times longer than the diameter of the heater body, enabling the total resistance of heater body 30 between the electrodes to be high enough to achieve sufficient temperatures while maintaining a compact size. In some examples, the material of the heater body 30 includes a nickel-chromium based super alloy.

[0070] In the illustrated embodiment, the body 30 includes an array or matrix of intersecting walls 40 (see, e.g., Figure 3 ), the intersecting walls form a plurality of channels (fluid flow paths) extending in an axial direction through the body 30, and thus are of a type that may be referred to as a honeycomb body. The channels provide flow paths that enable fluid to flow through the body 30 (e.g., an exhaust fluid flow), while the intersecting walls 40 act as resistive elements to generate heat when a voltage is applied to the body 30 and also provide surface area for heat exchange with the fluid flow. Each section of the walls 40 that are enclosed together to define a flow channel may be referred to herein as a cell 42. Thus, as Figure 2 and 3As shown in , the array of intersecting walls 40 defines a corresponding array of square cells 42 , which together form a honeycomb design for the body 30 .

[0071] As mentioned above, the body 30 includes slots 34 that form discontinuities, such as gaps, in the heater body 30 to disrupt electrical conductivity at certain locations in the body 30. For example, the slots 34 sever, break, disconnect, or otherwise electrically isolate portions of the body 30 from one another, thereby forcing current to flow in designated serpentine paths 32 around these disconnected portions. For example, the slots 34 can be air gaps or filled with an electrically insulating material. Each of the slots 34 includes an open end 44 where the slot 34 intersects the outer periphery 36 of the body 30 and a terminal end 46 where the slot 34 terminates within the heater body 30. Figure 3 In the example shown, the end 46 is round, but in other examples, the end 46 may be square.

[0072] like Figure 2 As shown in FIG, slots 34 extend alternately through body 30 from opposite sides thereof such that material of body 30 (eg, intersecting walls 40 ) is connected together in a serpentine pattern 32 that doubles back upon itself multiple times on body 30 .

[0073] like Figure 3 As further shown in FIG. 4 , the slots 34 have a width W and a length L extending from the open end 44 to the distal end 46 (only a portion of the length L is shown). If desired, such as in the illustrated embodiment, because the slots 34 intersect the periphery 36 over a small distance due to the curvature of the periphery 36, the length L of each slot 34 can be determined as the longest dimension of each slot 34 between the distal end 46 and the open end 44. The length L and / or width W can vary for different slots 34. Thus, the current carried between the electrodes 22 through the material of the body 30 is forced to follow the serpentine path 32. The shape or design of the serpentine path is not limited to that shown in the figures, as the number of slots 34 and the length, angle, width, or other dimensions can be set to define the shape and / or size of the serpentine path.

[0074] In embodiments where the heater body 30 is formed as a honeycomb design, such as in the illustrated embodiment where the heater body 30 includes an array of intersecting walls 40, the width W may be equal to the combined width of one or more entire cells 42 formed by the intersecting walls 40. For example, the width W may be equal to Figure 3 The width of one entire cell 42.

[0075] Thus, the electrical disconnection caused by the slots 34 enables the current path length between the electrodes 22 to be increased because the current is forced to traverse the body 30 multiple times rather than flowing directly in a straight line between the electrodes 22. Since the overall resistance of the heater body 30 depends (in part) on the overall current-carrying path length between the electrodes 22, the resistance of the heater assembly 18 can be set at least in part by selecting the size, location, and number of the slots 34 (thereby setting the parameters of the serpentine current-carrying path). For example, as described herein, the serpentine design enables the heater body 30 to be formed into a relatively small, thin disk of a desired metal alloy or other material, while typically at temperatures of hundreds of degrees Celsius.

[0076] In embodiments, the heater body 30 is at most 1 inch thick, at most 0.75 inches thick, at most 0.5 inches thick, e.g., 0.1 to 1 inch, 0.1 to 0.75 inches, 0.1 to 0.5 inches, or 0.25 to 0.5 inches, relative to the axial direction. In embodiments, the diameter (or widest dimension perpendicular to the axial direction) is at most 10 inches, at most 9 inches, at most 8 inches, at most 7 inches, at most 6 inches, at most 5 inches, at most 4 inches, e.g., 4 to 10 inches, although the dimensions of the heater body may be arranged based on a particular application, e.g., to correspond approximately to the cross-sectional dimensions of a catalyst substrate or filter with which the heater is used.

[0077] Because the slots 34 provide electrical isolation, the ends 46 of the slots 34 correspond to where the serpentine path 32 bends around the slots 34 and, therefore, represent where the current changes direction. It has been found that these bends in the serpentine path 32 can lead to increased heat generation and, therefore, the formation of high-temperature "hot spots" due to the concentration of current at the ends 46. That is, the current will tend to concentrate along the shortest path through the bend, which corresponds to the material of the heater body 30 that directly abuts and / or adjoins the ends 46 of the slots 34. Such hot spots can cause these areas of the heater body 30 to be particularly susceptible to premature failure, cracking, crazing, bending, warping, or other degradation in mechanical or thermomechanical properties or performance, particularly as the heater assembly 18 undergoes an increased number of heating and cooling cycles during use.

[0078] Furthermore, due in part to the concentration of current flowing through the material of the heater body 30 directly against the distal end 46, the material of the heater body 30 beyond the distal end 46 (in the direction that the slot 34 extends into the heater body 30) will cool more rapidly than both the hot spot and the remainder of the heater body 30. This rapid cooling occurs because less and less current is flowing through the material of the heater body 30 as the distance from the distal end 46 toward the periphery 36 increases.

[0079] Considering the above, and if Figure 2-3, the serpentine path 32 may be defined along a plurality of core segments 48 and a plurality of end regions 50 of the heater body 30. More specifically, each core segment 48 is defined as the conductive material of the heater body 30 extending between and along each pair of adjacent ones of the slots 34, while the end regions 50 include the conductive material in the area of the heater body 30 proximate the end 46 where the serpentine path 32 bends.

[0080] Examples of approximate regions corresponding to core segments 48 and end regions 50 are identified in the figures. However, because core segments 48 and end regions 50 are each formed from the conductive material of heater body 30 (e.g., core segments 48 and end regions 50 may be integrally formed from the conductive material as part of the same structure, such as both being formed from or being part of the array of intersecting walls 40 shown in the figures), there may not be a physically clear demarcation or boundary between these two regions. In practice, core segments 48 and end regions 50 may overlap to some extent and / or there may be a transition between them.

[0081] Figure 4 The formation of these hot and cooler spots is shown near the end 46 of the slot 34 . Figure 4 A portion of a heater body 30 is shown having two slots 34 forming a serpentine path 32 (not shown for clarity). The example heater body 30 includes an array of intersecting walls 40, which are divided into two groups: horizontal walls 40H and vertical walls 40V. The intersection of the horizontal walls 40H and the vertical walls 40V forms a plurality of cells 42. The horizontal walls 40H are defined as extending parallel to the main direction PD, while the vertical walls extend perpendicular to the main direction PD. The main direction is also parallel to each slot 34. Each of the walls 40H, 40V includes a conductive material, such as a metal, a metal alloy (or superalloy), or a metal composite. Thus, a current I flows from one end of the serpentine path to the other end via the wall 40. The current I flows along the path of least resistance. Thus, as current I flows along horizontal wall 40H toward end 46 of each slot 34, a high percentage of current I is "short-circuited" by flowing downward along vertical wall 40V adjacent end 46 rather than flowing in a more evenly distributed manner throughout heater body 30. This short-circuiting effect is caused by Figure 4. This high percentage of current I results in high Joule heating around the end 46 and, therefore, the formation of hot spots HS. These hot spots HS can adversely affect power consumption and temperature uniformity within the heater body 30. These hot spots HS limit the potential applications of the heater body 30 because the available material temperature window is largely consumed by the high temperatures at the hot spots HS. Similarly, the short-circuiting effect can also significantly reduce the current I reaching the outer corners of the serpentine path 32, leading to the formation of cold spots CS. The heater body 30 may not be able to adequately heat the exhaust gas traveling through the cells 42 within the cold spots CS, resulting in uneven heating and reduced efficiency of the heater body 30 as a whole.

[0082] Figure 5-7 Shown for reducing Figure 4 The novel non-uniform cell design is shown in Figure 2. Figure 4 similar, Figure 5 A portion of the heater body 30 is shown having two slots 34a, b forming a serpentine path 32 (not shown for clarity). The portion of the heater body 30 shown includes three core segments 48a-c and two end segments 50a, b. A first core segment 48a is coupled to a first end segment 50a. A second core segment 48b is coupled to the first end segment 50a and the second end segment 50b. A third core segment 48c is coupled to the second end segment 50b. Notably, each core segment 48a-c includes two types of cells 42: square cells 42q and skewed cells 42k. Although Figure 5-7 Each core segment 48a-c includes two rows of square cells 42q and skew cells 42k, but any number of rows may be implemented depending on the desired application. Figure 5 As can be seen in FIG, the square cell 42q is formed by intersecting horizontal walls 40H and vertical walls 40V, wherein the horizontal walls 40H extend parallel to the main direction PD and the vertical walls 40V extend perpendicular to the main direction PD. Thus, the shape of the square cell 42q formed by these intersections is substantially square, with four sides of approximately equal length intersecting at a ninety-degree angle. In contrast, the skew cell 42k is formed by horizontal walls 40H extending parallel to the main direction PD and vertical walls 40V intersecting at an angle 58 greater than or less than (but not equal to) ninety degrees (see FIG. Figure 6 ) is formed by the intersection of the skewed vertical walls 40V oriented in a direction of . Thus, these intersections form skewed units 42k having four sides of different lengths, which intersect to form non-ninety degree angles. The skewed units 42k can resemble rhombuses, parallelograms, trapezoids, or other non-rectangular shapes. Similarly, the end sections 50a, b include units 42 that are substantially trapezoidal in shape. Further regarding Figure 5 By way of non-limiting example, the deflecting unit 42k of each core segment 48a-c becomes increasingly deflected along the main direction PD and approaching the ends 46a,b of the slots 34a,b. Figure 6 As demonstrated, the varying skewness of cell 42 k may be described in terms of the intersection angle 58 formed by the intersecting walls 40 , the cross-sectional area of cell 42 , and / or the length of conductive path 60 .

[0083] Skewing the cells 42 of the heater body 30 near the ends 46a,b of the slots 34a,b reduces current concentration because the path of least resistance from each horizontal wall 40h surrounding each slot 34a,b no longer necessarily follows the vertical wall 40v immediately adjacent to the ends 46a,b. These dispersed current paths I are illustrated by downward-angled arrows where core segments 48a-c meet end segments 50a,b. In addition to reducing the effects of hot spots, the dispersed current I also reduces the effects of cold spots by directing the current I to the outer corners of the serpentine path 32. Reducing the effects of hot and cold spots enables the electric heater 18 to effectively utilize the temperature window of the material comprising the heater body 30 and improves gas temperature uniformity as the exhaust gas exits the cells 42 of the heater body 30. This skewing design can be easily manufactured using additive manufacturing or extrusion techniques without further innovation. In fact, skewing the cells 42 results in the use of less material than previous designs. Furthermore, the larger cross-sectional area of the skewed cells 42k, compared to the square cells 42q, results in lower fluid flow impedance through the heater body 30, enabling more efficient heat exchange between the heater body 30 and the exhaust gas. Furthermore, the reduction in hot spots reduces physical stress at the ends 46a, b due to excessive heating. The reduction in hot and cold spots is illustrated in greater detail in FIG8 .

[0084] Figure 6 yes Figure 5 A further illustration of the portion of the heater body 30 is shown in FIG. Figure 6 In the second core segment 48b (see Figure 5 ) is conceptually divided into three parts: a square unit portion 52 arranged between a first deflecting unit portion 54 and a second deflecting unit portion 56. The first deflecting unit portion 54 is coupled to the first end portion 50a (see Figure 5 ), and the second deflection unit portion 56 is coupled to the second end portion 50b (see Figure 5 The square cell portion 52 includes the square cells 42q of the second core segment 48b, while the first skewed cell portion 54 and the second skewed cell portion 56 include the skewed cells 42k of the second core segment 48b.

[0085] In some embodiments, the skew ratio of one of the core segments 48 may be determined as the total number of skew cells 42k divided by the total number of square cells 42q within the core segment 48. Figure 6In the illustrative embodiment of FIG, the skew ratio of the second core segment 48b can be approximately 2.00, and the first skew segment 54 and the second skew segment 56 each appear to have the same number of cells 42 as the square segment 52. However, in a more practical embodiment, the total number of square cells 42q in the core segment 48 can significantly exceed the number of skew cells 42k. In a preferred embodiment, and as will be shown in subsequent figures, the skew ratio can be 0.15 (or 15%), which means that the core segment has 6.67 square cells 42q for every skew cell 42k.

[0086] Figure 6 Further depicted are three intersection angles 58a-c formed by the intersecting horizontal walls 40H and vertical walls 40V within the second core segment 48b. The first intersection angle 58a is shown within the square unit portion 52 of the second core segment 48b. Figure 6 As shown in FIG, the first intersection angle 58a is approximately ninety degrees. In fact, due to the square shape of all cells 42 in the square cell portion 52, each intersection angle 58 in the square cell portion 52 is approximately ninety degrees.

[0087] A second intersection angle 58b is shown within the first deflection unit portion 54. As shown, the second intersection angle 58b is greater than ninety degrees, such as 120 degrees. Figure 6 As can be seen, the intersection angle 58b formed by the intersection of the horizontal wall 40H and the vertical wall 40V in the first deflection portion 54 gradually increases along the main direction PD until the first deflection portion 54 meets the first end section 50a (see Figure 5 In other examples, all (or a subset) of the intersection angles 58b within the first skewed unit portion 54 may be substantially equal.

[0088] A third intersection angle 58c is shown within the second deflection unit portion 56. As shown, the third intersection angle 58c shown is greater than ninety degrees, such as 120 degrees. Figure 6 As can be seen in the figure, the intersection angle 58b formed by the intersection of the horizontal wall 40H and the vertical wall 40V in the second skewed portion 56 gradually decreases along the main direction PD until the second skewed portion 56 meets the square unit portion 52. In other examples, all (or a subset) of the intersection angles 58b in the first skewed unit portion 54 may be substantially equal.

[0089] like Figure 6 As further shown in FIG, the third core segment 48c (see Figure 5) is conceptually divided into two parts: a square unit portion 62 arranged adjacent to a skewed unit portion 62. The skewed unit portion 62 is connected to the second end portion 50b. The square unit portion 52 includes the square units 42q of the third core segment 48c, while the skewed unit portion includes the skewed units 42k of the third core segment 48b. In addition, a fourth intersection angle 58d is shown within the third core segment 48c. The fourth intersection angle 58d is less than ninety degrees, for example, sixty degrees. As shown in Figure 6 As can be seen in FIG. 5 , the intersection angle 58 d formed by the intersection of the horizontal wall 40H and the vertical wall 40V in the skewed unit portion 62 gradually increases along the main direction PD until the skewed portion 62 meets the square unit portion 62 .

[0090] As the intersection angles 58a-d vary along the main direction, Figure 6 The cross-sectional areas of the cells 42 depicted in FIG can also vary in a similar manner. For example, the square cells 42q within the square cell sections 52, 62 of the second and third core segments 48b, c all have substantially equal cross-sectional areas. However, the cross-sectional areas of the skewed cells 42k within the first skewed section 54 of the second core segment 48a gradually increase along the principal direction PD. Conversely, the cross-sectional areas of the skewed cells 42k within the second skewed section 56 of the second core segment 48a and the skewed section 62 of the third core segment 48c gradually decrease along the principal direction PD.

[0091] Figure 6 Also shown is a path from the first horizontal wall 40H1 to the first slot 34 (see FIG. Figure 5 ) end 46a (see Figure 5 ) of several conductive paths 60a-c. These conductive paths 60a-c show that the length of each path 60a-c gradually changes along the main direction PD due to the skew shape of the corresponding unit 42. Figure 6 As can be seen in FIG. 5 , the first conductive path 60a is shorter than the second conductive path 60b, and the second conductive path 60 is shorter than the third conductive path 60c, which means that the lengths of the conductive paths 60a-c gradually increase along the main direction PD.

[0092] Figure 7 Show Figure 5 and 6 A variation of the portion of the heater body 30 in which the ends 46 of the slots 34 are substantially rounded. Tests have shown that rounding the ends 46 of the slots further reduces Figure 4 The effects of hot spot HS and cold spot CS are shown in .

[0093] exist Figure 7In some embodiments of the variations shown in , the rounded ends 46 of the slots 34 form a perfect (or nearly perfect) semicircular shape, such that the outermost deflected vertical walls 40V1-40V4 vertically intercept the corresponding rounded ends 46. This vertical arrangement prevents cracking of various aspects of the heater body 30 during thermal cycling.

[0094] exist Figure 7 In some embodiments of the variations shown in FIG, the heater body 30 may also be defined by a set of horizontal walls 40H1-40H9 and a set of vertical walls 40V5-40V8 disposed within the end sections 50a, b (see FIG. Figure 6 In some examples, the first plurality of intersections formed by horizontal wall 40H2 and vertical wall 40V5, horizontal wall 40H5 and vertical wall 40V5, horizontal wall 40H5 and vertical wall 40V7, and horizontal wall 40H8 and vertical wall 40V7 may be curved rather than substantially square. In some examples, each of the first plurality of intersections may be rounded rather than curved.

[0095] In other examples, the second plurality of intersections formed by the horizontal wall 40H1 and the vertical wall 40V6, the horizontal wall 40H6 and the vertical wall 40V6, the horizontal wall 40H4 and the vertical wall 40V8, and the horizontal wall 40H9 and the vertical wall 40V8 can be rounded rather than substantially square. In these rounded examples, the excess material on the inner edge of each of the second plurality of intersections forms a radius. This radius intersects perpendicularly with one of the outermost deflected vertical walls 40V1-40V4. The rounding of the second plurality of intersections rather than the curvature also maintains the overall shape of the heater body 30. Generally, replacing square intersections with curved or rounded intersections can prevent cracking during thermal cycling. In addition, the rounded second plurality of intersections allow the outermost horizontal walls 40H1, 40H9 to separate the deflected units 42k (see Figure 5 ) and the square unit 42q on the other side of the wall 40H1, 40H9 (see Figure 5 )connect.

[0096] exist Figure 5-7 In some embodiments of a non-uniform unit design, each skew unit 42k can be defined by a top horizontal dimension and a bottom horizontal dimension. In these embodiments, the top horizontal dimension of each skew unit 42k can have an equal length, and the bottom horizontal dimension of each skew unit 42k can also have an equal length. However, due to the skewed nature of the skew units 42k, the top horizontal dimension and the bottom horizontal dimension will have different lengths. This configuration can achieve improved current flow balance throughout the heater body 30.

[0097] Figure 8A and 8BModeling results for power density (watts per cubic meter) in two example heater bodies 30 a, b are shown. In these examples, power density is related to the amount of heat generated by the heater bodies 30 a, b, and therefore to the ability of the heater bodies 30 a, b to heat exhaust gas flowing through the passage formed by the array of intersecting walls. Figure 8A The heater body 30a corresponds to Figure 4 A design in which all cells are essentially square, and Figure 8B The heater body 30b corresponds to Figure 5 and 6 A design in which at least a portion of the cell near the end 46 of the slot 34 is substantially skewed.

[0098] Figure 8A and 8B This shows that the cooler zone within the square unit heater body 30a consumes a greater amount of power in the skewed unit heater body 30b, thereby creating a warmer zone rather than a cooler zone. Since the total power consumed by both heater bodies 30a, b is equal, the increase in power in the warmer zone of heater body 30b necessarily also reduces the power in the original warmer zone. Therefore, Figure 8B The skewed design of the heater body 30b enables a more uniform power density distribution, thereby reducing power consumption at the hottest portion of the heater body 30b.

[0099] Figure 9A and 9B Show Figure 8A and 8B Modeling results of the power density of the peak power consumption portion of two example heater bodies 30a, b. Figure 9A and 9B All focus on the portion of the vertical walls 40Va, 40Vb adjacent to the slot 34. Figure 9A As shown in FIG, the peak power density within the vertical wall 40Va of the square unit heater body 30a is mostly constant throughout the circled portion. Figure 9B As shown in FIG, the peak power density within the vertical wall 40Vb of the skewed unit heater body 30b is not constant, such that the vertical wall 40Vb consumes less total power than the vertical wall 40a.

[0100] Figures 10A-15B As shown in the previous figures, the heater body 30 may include a through-end section 50 (see Figure 5 ) connected to the plurality of core segments 48 (see Figure 5 ) to surround the plurality of slots 34 cut into the heater body 30 (see Figure 5 ) forms a conductive meandering path 32 (see Figure 2Each of these core segments 48 comprises a plurality of square cells 42q (see Figure 5 ) and multiple deflection units 42k (see Figure 5 The deflection elements 42k are arranged around the ends 46 of the slots 34 to reduce the effects of hot and cold spots.

[0101] As previously discussed, the skew ratio can be determined as the total number of skew cells 42k divided by the total number of square cells 42q within the core segment 48. Modeling has shown that optimal performance of the heater body 30 is achieved by designing each core segment 48 to have an equal skew ratio. Because the length of the core segments 48 may fluctuate throughout the heater body 30, the number of square cells 42q and skew cells 42k should be adjusted to maintain an equal skew ratio in each core segment 48.

[0102] Figure 10A A front view of a model of a heater body 30 is shown having a plurality of core segments 48. As can be seen, each core segment 48 includes approximately the same number of skew cells 42k. However, as the length of the core segment 48 varies, the core segment 48 will include a different number of square cells 42q. Therefore, core segments 48 of different lengths will necessarily have different skew ratios.

[0103] Figure 10B Shown based on Figure 10A The temperature profile of the heater body 30 modeled by . This temperature profile shows the impact of failing to implement the equal skew ratio design rule. Figure 10B As can be seen in the figure, the temperature in the shorter core segment 48 is significantly higher than that in the longer core segment. Even though the deflected elements 42k reduce the temperature around the ends 46 of the slots, the middle portion of the shorter core segment 48 reaches a temperature exceeding 1000 degrees Celsius, exceeding the acceptable limit of the material comprising the heater body 30. In addition, the non-uniform nature of the temperature profile reduces the overall efficiency of the heater body 30.

[0104] Figure 11A A heater body 30 is shown implementing the equal skew ratio design rule. As the length of the core segment 48 varies, the number of square cells 42q and skew cells 42k adjusts to maintain an equal skew ratio throughout the heater body 30. Figure 11B The impact of the equal skew ratio design rule is shown in FIG. Figure 11B Shown based on Figure 11A Modeled temperature profile of the heater body 30. Compared to Figure 10B The cross section, Figure 11B The modeled temperature profile is more evenly distributed in the different core segments, resulting in more efficient heating of the exhaust gases. Figure 11B The peak temperature of the cross section is significantly lower than Figure 10BTherefore, implementing the equal skew ratio design rule achieves significant improvements in temperature distribution and peak temperature.

[0105] Figure 12 A model of a baseline heater body 30BAS is shown for use with an equal skew ratio design rule implemented. Figure 11A The reference heater body 30BAS includes only the square unit 42q, similar to Figure 4 The portion of the heater body 30 shown in FIG. The baseline heater body 30BAS also implements a series of V-shaped features 64 for hot spot relief purposes. The V-shaped features 64 generally comprise the same conductive material as the rest of the baseline heater body 30BAS, such as a metal, metal alloy, or metal composite.

[0106] Figure 13 and 14 Comparison of the baseline heater body 30BAS with Figure 11A 1 and 2. Modeled temperature performance of the heater body 30 implementing the equal skew ratio design rule. In these graphs, "square" refers to the baseline heater body 30 BAS, while "skew" refers to the heater body 30 implementing the equal skew ratio design rule.

[0107] Figure 13 The maximum temperature over time was compared for the square design and the skewed design. Figure 13 It is shown that the skewed design not only heats up faster than the square design, but the skewed design also maintains a lower peak temperature as it approaches thermal equilibrium. Figure 13 The square design is shown to have a peak temperature of 967 degrees Celsius at 25 seconds, while the skewed design is 45 degrees Celsius cooler (922 degrees Celsius). Because the skewed design has a slightly lower thermal mass than the square design, the skewed design heats up faster than the square design. The lower thermal mass also provides the additional benefit of reduced material costs. In addition, the reduced peak temperature of the square design improves reliability and extends the operating window of the heater body 30 implementing the skewed design.

[0108] Figure 14 The gas temperature uniformity factor is compared over time. The gas temperature is measured 25 mm downstream of the square and skewed heater bodies. Figure 14 It is shown that the skewed design provides improved uniformity relative to the square design.

[0109] Figure 15A The gas temperature distribution at 25 mm downstream of the square design is shown. Similarly, Figure 15B The gas temperature distribution at 25 mm downstream of the skew design is shown. Figure 15A and 15BAs shown in , the skewed design produces a more uniform temperature distribution than the square design. In addition, the skewed design produces a higher mass-weighted average temperature (526 degrees Celsius) at 25 mm downstream than the square design (514 degrees Celsius).

[0110] It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the scope or spirit of the claimed subject matter.Accordingly, the claimed subject matter should not be restricted except in light of the appended claims and their equivalents.

Claims

1. An electric heater body, comprising: Periphery; a plurality of slots, each slot extending from the periphery to a terminal end within the electric heater body; a plurality of core segments comprising a conductive material, wherein each core segment is defined between a different pair of adjacent slots, and wherein the conductive material is shaped into an array of intersecting walls defining a honeycomb cell pattern; as well as a plurality of end regions comprising the conductive material, wherein each end region is between a respective one of the ends of the slot and the outer periphery, and wherein each pair of adjacent core segments is connected by a corresponding one of the plurality of end regions; wherein the plurality of slots disconnect each pair of adjacent core segments from each other to form a conductive meandering path; and wherein a first set of the array of intersecting walls extends in a main direction parallel to the plurality of slots, a second set of the array of intersecting walls intersects the first set of walls at a plurality of intersection angles, and At least a portion of the plurality of intersection angles in each of the plurality of core segments varies along the primary direction.

2. The electric heater body of claim 1 , wherein each of the plurality of core segments comprises: a square unit portion, wherein each of the plurality of intersection angles within the square unit portion is substantially ninety degrees; a first skewed unit portion coupling the square unit portion to a first end region of the plurality of end regions, wherein each of the plurality of intersection angles within the first skewed unit portion is greater than ninety degrees; as well as A second skewed unit portion couples the square unit portion to a second end region of the plurality of end regions, wherein each of the plurality of intersection angles within the second skewed unit portion is greater than ninety degrees. 3 . The electric heater body according to claim 2 , wherein within the first skewed unit portion, the plurality of intersection angles gradually increase in size along the main direction from the square unit portion toward the first end region.

4. The electric heater body of claim 2, wherein within the second skewed unit portion, the plurality of intersection angles gradually decrease in size along the main direction from the second end region toward the square unit portion.

5. The electric heater body of claim 2, wherein each core segment of the plurality of core segments has an equal skew ratio.

6. The electric heater body of claim 5, wherein the skew ratio of one of the plurality of core segments is defined as a ratio of the number of cells in the first and second skewed cell portions to the number of cells in the square cell portion.

7. The electric heater body of claim 5, wherein each core segment of the plurality of core segments has a skew ratio of approximately fifteen percent.

8. The electric heater body of claim 1, wherein a portion of the honeycomb cell pattern within the plurality of end regions is substantially trapezoidal.

9. The electric heater body of claim 1, wherein the electrically conductive material comprises a metal, a metal alloy, a metal composite, or a combination thereof.

10. The electric heater body of claim 1, wherein the electrically conductive material is a nickel-chromium based super alloy.

11. The electric heater body of claim 1 , wherein the electric heater body is formed via additive manufacturing or extrusion.

12. The electric heater body of claim 1, wherein the end of each slot of the plurality of slots is rounded.

13. An electric heater assembly comprising the electric heater body of claim 1 coupled to a pair of electrodes at opposite ends of an electrically conductive serpentine path.

14. An electric heater body, comprising: Periphery; a plurality of slots, each slot extending from the periphery to a terminal end within the electric heater body; a plurality of core segments comprising a conductive material, wherein each core segment is defined between a different pair of adjacent slots, and wherein the conductive material is shaped into an array of intersecting walls defining a honeycomb cell pattern; a plurality of end regions comprising the conductive material, wherein each end region is between a respective one of the ends of the slot and the outer periphery, and wherein each pair of adjacent core segments is connected by a corresponding one of the plurality of end regions; wherein the plurality of slots disconnect each pair of adjacent core segments from each other to form a conductive meandering path; and The cross-sectional area of at least a portion of the honeycomb unit pattern varies along a main direction parallel to the plurality of slots.

15. The electric heater body of claim 14, wherein each core segment of the plurality of core segments comprises: a square cell portion, wherein the square cross-sectional area of each cell in the honeycomb cell pattern within the square cell portion is substantially equal; a first skewed cell portion coupling the square cell portion to a first end region of the plurality of end regions, wherein a first skewed cross-sectional area of each cell in the honeycomb cell pattern within the first skewed cell portion is greater than the square cross-sectional area; as well as A second skewed cell portion couples the square cell portion to a second end region of the plurality of end regions, wherein a second skewed cross-sectional area of each cell in the honeycomb cell pattern within the first skewed cell portion is greater than the square cross-sectional area.

16. An electric heater body according to claim 15, wherein within the first skewed cell portion, the cross-sectional area of each cell gradually increases along the main direction from the square cell portion towards the first end region.

17. The electric heater body of claim 15, wherein within the second skewed cell portion, the cross-sectional area of each cell gradually decreases along the main direction from the second end region toward the square cell portion.

18. The electric heater body of claim 14, wherein the distal end of each of the plurality of slots is rounded.

19. The electric heater body of claim 14, wherein each core segment of the plurality of core segments has an equal skew ratio.

20. An electric heater body, comprising: Periphery; a plurality of slots, each slot extending from the periphery to a terminal end within the electric heater body; a plurality of core segments comprising a conductive material, wherein each core segment is defined between a different pair of adjacent slots, and wherein the conductive material is shaped into an array of intersecting walls defining a honeycomb cell pattern; as well as a plurality of end regions comprising the conductive material, wherein each end region is between a respective one of the ends of the slot and the outer periphery, and wherein each pair of adjacent core segments is connected by a corresponding one of the plurality of end regions; wherein the plurality of slots disconnect each pair of adjacent core segments from each other to form a conductive meandering path; and A first group of the array of intersecting walls extends in a main direction parallel to the plurality of slots, a second group of the array of intersecting walls intersects the first group of walls at a plurality of intersection angles, and each of a plurality of conductive paths defined as from the first group of the array of intersecting walls to one of the slots gradually changes along the main direction.

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