A serpentine heater with a functional section for reducing hot spots at the slot ends.

Abstract

The heater body includes an outer circumferential surface. A plurality of slots extend from the outer circumferential surface and terminate within the heater body. A plurality of core segments are defined between adjacent pairs of slots. A plurality of bend regions are disposed about each end of the slots. Each pair of adjacent core segments is connected by a corresponding one of the bend regions. A supplemental conductive feature is located in each of the bend regions. The plurality of slots electrically separate each pair of adjacent core segments from one another to form a serpentine current carrying path that extends through the heater body through the conductive material of the core segments and the bend regions. Each of the supplemental conductive features locally reduces electrical resistance of the heater body in the bend region as compared to the conductive material alone.

Description

Related Applications

[0001] This application claims the benefit of priority under 35 U.S.C. § 119 from U.S. Provisional Patent Application No. 63 / 183,573, filed on May 3, 2021, the benefit of priority under 35 U.S.C. § 119 from Indian Patent Application No. 202111055328, filed on November 30, 2021, and the benefit of priority under 35 U.S.C. § 119 from U.S. Provisional Patent Application No. 63 / 319,374, filed on March 13, 2022, the contents of which are incorporated herein by reference in their entirety and relied upon.

Technical Field

[0002] The present disclosure relates to a heater assembly comprising a honeycomb body, particularly a honeycomb body having a serpentine current transfer path defined by slots extending within the honeycomb body, and an exhaust aftertreatment system comprising such a heater assembly.

Background Art

[0003] Pollution reduction systems, such as exhaust aftertreatment systems coupled to internal combustion engines, e.g., internal combustion engines of automobiles or other vehicles, may include a heater assembly that provides auxiliary heat to assist in the operation of the system. For example, a catalyst material used in a catalyst converter or other aftertreatment component that includes a catalyst may require a minimum temperature to initiate a catalytic reaction, which is also referred to as catalyst light-off.

[0004] In internal combustion engines, heat can be supplied from the exhaust flow itself, but each time the engine is started for the first time, it can take some time for the exhaust temperature to rise sufficiently, a phenomenon known as a cold start. Even if the system is configured to heat the catalyst to its light-off temperature within a few seconds with respect to the exhaust flow, these first few seconds after a cold start can significantly impact the overall engine emissions, sometimes even making up the majority of them. Therefore, the auxiliary heat provided by the heater assembly can greatly reduce the time it takes for the catalyst to reach its light-off temperature, thereby reducing emissions, especially after a cold start event. [Overview of the Initiative]

[0005] This specification discloses, for example, a heater body for an exhaust aftertreatment assembly. In an embodiment, the heater body has an outer circumferential surface and; a plurality of slots, each extending from the outer circumferential surface and terminating at an end within the heater body; a plurality of core segments made of a conductive material, each defined between different adjacent pairs of slots; a plurality of bent regions made of a conductive material, each bent region being positioned around one of the ends of the slots, and each pair of adjacent core segments being connected by the corresponding bent region of the bent region; and auxiliary conductive functional parts positioned in each of the bent regions adjacent to each of the ends, wherein the plurality of slots electrically isolate each pair of adjacent core segments from one another in order to form a meandering current transmission path extending through the conductive material of the core segments and bent regions across the heater body, and each of the auxiliary conductive functional parts locally reduces the electrical resistance of the heater body in the bent region compared to the case of the conductive material alone.

[0006] In this embodiment, each auxiliary conductive functional part has a filleted or rounded corner at the end of the slot.

[0007] In this embodiment, the conductive material consists of a foam, a lattice, or woven fibers, filaments, or wires that form a plurality of channels that penetrate the heater body in the axial direction.

[0008] In this embodiment, the conductive material is formed as an array of intersecting walls that define multiple cells in a honeycomb design.

[0009] In the embodiment, each auxiliary conductive functional part includes one or more cells in a bending region that are completely filled with a supplemental conductive material.

[0010] In the embodiment, each auxiliary conductive functional part includes one or more cells in a bending region that are at least partially filled with a supplemental conductive material.

[0011] In this embodiment, each auxiliary conductive functional section includes a continuous strip of supplemental conductive material.

[0012] In this embodiment, the strip includes a plurality of wedge-shaped portions, each of which partially fills a corresponding cell among the cells.

[0013] In this embodiment, the wedge-shaped portion has a linear inclined surface.

[0014] In this embodiment, the wedge-shaped portion is formed in a corrugated shape with a nonlinear inclined surface.

[0015] In this embodiment, the wedge-shaped portion increases in width across each cell from a minimum dimension of 0% to 25% of the cell width to a maximum dimension of 25% to 100% of the cell width.

[0016] In the embodiment, each auxiliary conductive functional section includes a continuous strip of thickened walls that are thicker than the intersecting walls.

[0017] In the embodiment, the thickened wall includes a plurality of arms extending from the bending region toward each core segment.

[0018] In this embodiment, each auxiliary conductive functional section includes a thickened boundary wall that forms the boundary of the end portion of the slot.

[0019] In this embodiment, each auxiliary conductive functional part extends at least partially along the length of the slot.

[0020] In this embodiment, each auxiliary conductive functional part extends at least partially along the length of the slot on both opposing sides of the slot.

[0021] In the embodiment, at least a portion of each auxiliary conductive functional part that extends at least partially along the length of the slot is also separated from the slot.

[0022] In this embodiment, the conductive material is formed as an array of intersecting walls defining multiple cells in a honeycomb design, with a portion of each auxiliary conductive functional part separated from the slot by at least one cell width.

[0023] In this embodiment, the auxiliary conductive functional portion extends continuously from a first core segment among the multiple core segments, through a bending region, to a second core segment among the multiple core segments.

[0024] In one embodiment, the heater assembly comprises the heater body described in any one of the preceding paragraphs, which is connected to electrode pairs at both ends of the meandering path.

[0025] In this embodiment, the exhaust aftertreatment assembly comprises the heater assembly described in the previous paragraph and aftertreatment components connected to a common housing or piping.

[0026] In this embodiment, the post-processing component comprises a porous ceramic honeycomb body.

[0027] In the embodiment, the heater body, the post-treatment component, or both thereof, includes a catalyst material.

[0028] 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 characteristics of the claimed subject matter. The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding. The drawings illustrate one or more embodiments and, together with the description, serve to explain the principles and operations of the various embodiments.

Brief Description of the Drawings

[0029] [Figure 1] It is a cross-sectional view showing an exhaust aftertreatment assembly according to an embodiment disclosed herein. [Figure 2] It is a front view showing an electrical heater assembly having a serpentine design formed by a plurality of electrically insulating slots, a plurality of core segments between adjacent pairs of slots, and a bending region adjacent to the end portions of each slot and connecting adjacent core segments to each other according to an embodiment disclosed herein. [Figure 3] It is a view showing a part of a heater body provided with an auxiliary conductive functional part in a bending region of the heater body, having filleted or rounded corners at the intersections between the walls according to an embodiment disclosed herein. [Figure 4] It is a view showing a part of a heater body provided with an auxiliary conductive functional part in a bending region of the heater body, having a plurality of honeycomb cells completely filled with a conductive material according to an embodiment disclosed herein. [Figure 5] It is a view showing a part of a heater body provided with an auxiliary conductive functional part in a bending region of the heater body, having a plurality of honeycomb cells partially filled with a conductive material according to an embodiment disclosed herein. [Figure 6A] It is a view schematically showing each current path for a heater body without an auxiliary conductive functional part according to an embodiment disclosed herein. [Figure 6B]This figure schematically shows the current paths for a heater body having an auxiliary conductive functional part according to embodiments disclosed herein. [Figure 7A] This figure shows a portion of a heater body having an auxiliary conductive functional section in a bent region of the heater body, which has a strip of conductive material, according to an embodiment disclosed herein. [Figure 7B] This is an enlarged view of a portion of the strip in Figure 7A, showing the wedge-shaped morphology of the honeycomb cells that are partially filled. [Figure 8] This figure shows a portion of a heater body having an auxiliary conductive functional portion in a bent region of the heater body, which has a strip of conductive material having a plurality of corrugated wedge-shaped portions, according to an embodiment disclosed herein. [Figure 9A] This figure shows a portion of a heater body, according to an embodiment disclosed herein, in which an auxiliary conductive functional section having a thickened wall strip is provided in a bent region of the heater body. [Figure 9B] This figure shows a portion of a heater body, according to an embodiment disclosed herein, in which an auxiliary conductive functional section having a thickened wall strip is provided in a bent region of the heater body. [Figure 9C] This figure shows a portion of a heater body, according to an embodiment disclosed herein, in which an auxiliary conductive functional section having a thickened wall strip is provided in a bent region of the heater body. [Figure 9D] This figure shows a portion of a heater body, according to an embodiment disclosed herein, in which an auxiliary conductive functional section having a thickened wall strip is provided in a bent region of the heater body. [Figure 9E] This figure shows a portion of a heater body, according to an embodiment disclosed herein, in which an auxiliary conductive functional section having a thickened wall strip is provided in a bent region of the heater body. [Figure 9F] This figure shows a portion of a heater body, according to an embodiment disclosed herein, in which an auxiliary conductive functional section having a thickened wall strip is provided in a bent region of the heater body. [Figure 10]This figure shows a portion of a heater body having an auxiliary conductive functional section in a bent region of the heater body, having a supplementary wall extending across the honeycomb cell, according to an embodiment disclosed herein. [Figure 11] This figure shows a portion of a heater body having an auxiliary conductive functional section in a bent region of the heater body, with a thickened boundary wall around the end of the slot, according to an embodiment disclosed herein. [Modes for carrying out the invention]

[0030] Next, the exemplary embodiments shown in the attached drawings will be described in detail. To refer to the same or similar parts, the same reference numerals will be used throughout the drawings whenever possible. Components in the drawings are not necessarily to scale; instead, the emphasis is on illustrating the principles of the exemplary embodiments.

[0031] Numerical values ​​including the endpoints of a range may be expressed herein as approximations to which terms such as “approximately” or “about” are assigned. In such cases, another embodiment includes a specific numerical value. Whether or not the numerical value is expressed as an approximation, two embodiments are included in this disclosure: one in which it is expressed as an approximation and another in which it is not. Furthermore, it is understood that the endpoints of each range are significant both in relation to and independently of the other endpoints.

[0032] Those skilled in the art and those who create or use this disclosure will likely come up with modifications to this disclosure. Therefore, it will be understood that the embodiments shown in the drawings and described herein are for illustrative purposes only and are not intended to limit the scope of this disclosure as defined by the following claims, to be interpreted in accordance with the principles of patent law, including the doctrine of equivalents.

[0033] As used herein, the term “approximately” means that quantities, sizes, formulations, parameters, and other quantities and characteristics are not, and do not need to be, exact, and may be approximate and / or greater or less, and reflect tolerances, conversion factors, rounding, measurement errors, etc., and other factors known to those skilled in the art, if desired. Where the term “approximately” is used in a description of an endpoint of a value or range, this disclosure should be understood to include the specific value or endpoint mentioned.

[0034] The terms used herein to indicate direction, such as up, down, right, left, front, back, top, and bottom, are given only with reference to the illustrated figures and are not intended to imply absolute directions. The term “radial direction” as used herein refers to a direction perpendicular to the indicated axial direction, extending from the center point of a shape (e.g., see central axis C in Figure 2) to or toward the outer surface of the shape, regardless of the shape of the component or feature on which the term “radial direction” is used. Similarly, the term “diameter” as used herein is not limited to a circle, but instead refers to the longest dimension of a component that passes through the center point (central axis) of the shape of that component. For example, the radial distance of a square component can be measured as the straight-line distance from the center point (central axis) to the intersection with one of the walls of the square, and the diameter of the square refers to the longest dimension that diagonally crosses the square. The terms “section width” or “section dimension” may be used to refer to these directions perpendicular to the axial direction.

[0035] Fluid treatment systems, such as automotive exhaust aftertreatment systems or other pollution reduction systems, may be equipped with an auxiliary heat source to facilitate operation, for example, in the case of a catalyst-containing system, to enable faster catalyst light-off. For example, heat can be supplied by an electric heater (e.g., positioned to transfer heat to the catalyst material) or by an electrically heated catalyst substrate (e.g., a conductive substrate supporting the catalyst material). For example, the catalyst can be heated by placing the heater upstream of the catalyst substrate and supplying heat to the exhaust flow (or auxiliary airflow), which then heats the catalyst. To reduce emissions in gasoline, diesel, and / or hybrid vehicles, aftertreatment systems using auxiliary heat can be provided to help ensure a rapid and consistent light-off of the catalyst during the operation of the corresponding engine, particularly after a cold start of the engine.

[0036] Referring here to Figure 1, a fluid handling assembly 10 is shown, which can be installed, for example, as part of the exhaust system of an automobile. The fluid handling assembly 10 includes an outer housing 12 (sometimes referred to as an alternative "can"), which is formed in a generally tubular shape (e.g., a hollow tube) from metal or a suitable material. The outer housing 12 has an inlet 14 that can be connected in fluid communication to, for example, the exhaust manifold of an internal combustion engine, and an outlet 16 that can be connected in fluid communication to, for example, the tailpipe of an automobile.

[0037] Exhaust or other fluid flow from an engine (the fluid flow to be treated, generally referred to herein as “exhaust”) can be treated as the exhaust flows through the assembly 10 from the inlet 14 to the outlet 16 (e.g., one or more contaminants are removed or reduced). For this purpose, the assembly 10 further includes a heater assembly 18 and a post-treatment component 20 located between the inlet 14 and the outlet 16. For example, the post-treatment component 20 may be a catalyst-supported substrate, a particulate filter, or a catalyst-supported 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 passages or channels extending axially (perpendicular to the direction of the exhaust flow and / or the end faces of the body) through the body.

[0038] As described in detail herein, the heater assembly 18 may be a resistance heater that provides auxiliary heat to facilitate the function of the after-treatment component 20 by, for example, rapidly initiating the light-off of catalyst material disposed within or on the walls of the heater assembly 18 and / or the after-treatment component 20. For example, the heater assembly 18 may include an electrode 22, or may be otherwise connected to the electrode 22. The electrode 22 may be positioned to extend through the housing 12 to connect the heater assembly 18 to a power source, such as a vehicle battery. As shown in Figure 1, the electrode 22 may extend radially through the housing 12. However, the electrode 22 may alternatively extend axially through the housing 12, and / or one electrode may extend radially and the other electrode may extend axially. In this way, the heater assembly 18 can be configured to generate heat by Joule heating by connecting the heater assembly 18 to a power source and applying a corresponding voltage to pass current through the walls of the heater assembly 18. Although the electrodes 22 are shown in Figure 1 to be positioned on opposite sides of the heater assembly 18 (for example, 180° apart with respect to the outside of the heater assembly 18), they may be positioned at other locations or angles.

[0039] In embodiments disclosed herein, such as that shown in Figure 1, the heater assembly 18 is positioned upstream of the after-treatment component 20 (relative to the direction of the exhaust flow) to increase the temperature of the exhaust flow and / or provide direct heating to the after-treatment component 20. This, in turn, increases the temperature of the after-treatment component 20, such as the temperature of the catalyst material supported by the after-treatment component 20, as the exhaust flow passes through it. In some embodiments, the heater assembly 18 and the after-treatment component 20 can be effectively combined into a single device by directly supporting the catalyst on the body of the heater assembly 18. Such a configuration useful for heating catalyst material may be called an electroheated catalyst, or EHC.

[0040] A vehicle exhaust system can be formed by connecting additional length piping (not shown) to the assembly 10 at the inlet 14 (extending, for example, between the inlet 14 and the engine exhaust manifold) and the outlet 16 (extending, for example, from the outlet 16 to the tailpipe). Depending on the design or configuration of the exhaust system for each vehicle, the various components and / or lengths of the piping may have different diameters at different locations along the flow path through the exhaust system.

[0041] The heater assembly 18 and the post-processing components 20 can be held, supported and / or housed in place within the housing 12 in any suitable form. For example, the body of the heater assembly 18 can be held in place and supported via one or more retaining devices 24, such as retaining rings. The post-processing components 20 can be supported by similar retaining devices and / or by a mat 26, such as an inorganic fiber mat, which helps protect the post-processing components from vibrations or thermal expansion forces applied to them during operation.

[0042] Referring here to Figures 2 and 3, one embodiment of the heater assembly 18 is shown. Consistent with the disclosure herein, the embodiments illustrated and / or described herein can be used as the heater assembly 18 in assembly 10 or incorporated into the heater assembly 18 in assembly 10, and combinations of features of the embodiments illustrated or described herein can be used together for the heater assembly 18 in assembly 10.

[0043] As further described herein, the heater assembly 18 comprises a heater body 30 made of a conductive material extending in a meandering current transmission path (or simply “meandering path”) between a pair of electrodes (e.g., electrode 22 not shown in Figures 2 and 3). A portion of the meandering path for the heater body 30 is identified by a dashed line and reference numeral 32 in Figure 2. As further described herein, the meandering path 32 for the body 30 is made up of a plurality of slots 34 extending from the outer circumferential surface 36 of the body 30 into the body 30.

[0044] The flow of current along the meandering path 32 of the heater body 30 can be achieved through electrodes such as electrodes 22 (not shown in Figure 2) at both ends of the meandering path 32. The electrodes or a portion of the electrodes can be formed integrally with the heater body 30, or they can be separately attached, for example, to a corresponding electrode mounting area 38 by mechanical fastening or welding. In this way, an electrical connection can be established along the meandering path 32 through the body 30 via electrodes fixed at both ends. For example, the characteristics of the honeycomb body 30, such as the dimensions of the honeycomb body 30, the length of the meandering path 32, the area of ​​the conductive material of the heater body 30 available for current flow per unit length along the meandering path, and / or the resistivity of the material of the honeycomb body 30, can be set with respect to a target voltage or selected voltage to be applied to the electrodes 22 to generate heat by resistive heating as the current passes through the material of the heater body 30.

[0045] In the embodiment, the heater body 30 is positioned with respect to a selected voltage (e.g., the voltage available from the vehicle battery to the heater assembly 18) so that it reaches a temperature suitable for catalytic light off, for example, about 700°C to 1000°C, although other temperatures may be targeted based on the application of the heater assembly 18 and / or the thermomechanical properties of the material selected for the heater body 30. In the embodiment, the material of the heater body includes metal or metal alloy. For example, various metal alloys are particularly advantageous for use in resistance heating elements due to their thermomechanical, environmental resistance, and electrical properties. In the embodiment, the metal includes alloys containing one or more of nickel, chromium, iron, and / or aluminum, for example, nickel-chromium alloy or iron-chromium-aluminum alloy, but other materials suitable for use in or as resistance heaters may also be used. However, since these materials contain metal, they generally have fairly high conductivity. Advantageously, the meandering design traversing front to back as described herein allows the current transmission path length for the heater body to be several times longer than the diameter of the heater body, thereby making the total resistance of the heater body 30 between electrodes high enough to reach a sufficient temperature while maintaining a compact size relative to the heater body.

[0046] In the illustrated embodiment, the body 30 includes an array or matrix of intersecting walls 40 (see, for example, Figures 3A-3B) that form a plurality of channels (fluid passages) extending axially through the body 30, and thus the body 30 is of a type that may be called a honeycomb body. The channels provide passages (e.g., exhaust fluid flow) that allow fluid to flow through the body 30, while the intersecting walls 40 act as resistive elements that generate heat when a voltage is applied to the body 30 and also provide a surface area for heat exchange with the fluid flow. Each section of the walls that surrounds together to define a flow channel may be called a cell 42 in this specification. Thus, in Figures 2 and 3, the array of walls 40 defines a corresponding array of square cells 42, and the cells 42 together create a honeycomb design for the body 30. However, the walls 40 can also be arranged in other patterns to form cells 42 having any other desired cross-sectional shape (shape perpendicular to the axial direction), such as hexagons, triangles or other polygons.

[0047] Furthermore, instead of cells and channels having regular and / or repeating geometric shapes, the body 30 may have openings and / or meandering channels of irregular shape and size, such as an irregularly interconnected porous structure. For example, in an embodiment, the body 30 includes a grid, foam or woven fibers, wire or filament (or other elongated fibrous or wire-like elements) of a conductive material, in which case the channels through the body 30 are irregularly formed by holes, voids, openings or gaps in the grid structure or foam structure and / or between the woven fibers or fibrous elements of the conductive material. Thus, the honeycomb, grid, foam and woven fiber or wire designs are all similar in that they have channels that allow fluid to flow axially through the body, while on the other hand, the conductive material functions as a resistive heating element that generates heat, while at the same time providing a surface area for heat transfer by the flow of fluid (e.g., exhaust gas) through the heater. In the embodiment, the body 30 can be formed by additive manufacturing, stamping or perforating a sheet of conductive material, weaving wire, fibers or filaments into a mesh, mat or screen, foaming a conductive material, or other suitable process. Thus, whether the heater body 30 includes a honeycomb structure, a lattice structure, a foamed structure, a porous structure or a woven structure, the honeycomb body 30 includes a plurality of channels that penetrate the body axially, enabling heat transfer between the fluid flow and the conductive material forming the channels.

[0048] As described above, the main body 30 has slots 34 that form separation portions, such as gaps, in the heater body 30 to interrupt conductivity at predetermined locations of the main body 30. For example, the slots 34 reliably isolate, separate, or otherwise electrically insulate portions of the main body 30 from one another, thereby forcing current to flow through designated meandering paths 32 around these isolated portions. For example, the slots 34 may be air gaps or may be filled with electrically insulating material. Each slot 34 has an open end 44 where the slot 34 intersects the outer circumferential surface 36 of the main body 30, and a termination portion 46 where the slot 34 terminates within the heater body 30.

[0049] As shown in Figure 2, the slots 34 extend alternately across the body 30 from opposite sides of the body 30, so that the material of the body 30 (e.g., intersecting walls 40) folds back itself and connects with each other in a meandering pattern that crosses the body 30 multiple times.

[0050] Furthermore, as shown in Figure 3, each slot 34 has a width W and a length L extending from the open end 44 to the terminal end 46 (only a portion of the length L is shown). Since the outer surface 36 is curved, the slots 34 intersect the outer surface over a small range of intervals, so the length L of each slot 34 can, if necessary, be defined as the longest dimension of each slot 34 between the terminal end 46 and the open end 44, for example, as in the illustrated embodiment. The length L and / or width W may vary for different slots 34. As a result, the current transmitted between the electrodes 22 through the material of the body 30 is forced to flow along the meandering path 32. The number and length, angle, width, and other dimensions of the slots 34 may be set to define the shape and / or dimensions of the meandering path, so the shape and design of the meandering path are not limited to those shown.

[0051] In embodiments where the heater body 30 is formed as a honeycomb design, such as in the illustrated embodiment which includes an intersecting array of walls 40, the width W may be equal to the combined width of one or more complete cells 42 formed by the intersecting walls 40. For example, in Figure 3, the width W is equal to the width of one complete cell 42.

[0052] Therefore, the current is forced to traverse the body 30 multiple times, rather than flowing directly in a straight line between the electrodes 22, so that the electrical isolation created by the slots 34 can increase the length of the current path between the electrodes 22. Since the total resistance of the heater body 30 depends (partially) on the total length of the current transmission path between the electrodes 22, the electrical resistance of the heater assembly 18 can be set, at least partially, by selecting the dimensions, position, and number of the slots 34 (therefore setting the parameters of the meandering current transmission path). For example, as described herein, the meandering design allows the heater body 30 to be formed as a relatively small, thin disc made of a desired metal alloy or other material, while also enabling temperatures of several hundred degrees Celsius in general.

[0053] In the embodiment, with respect to the axial direction, the heater body 30 has a maximum thickness of 1 inch (25.4 mm), a maximum thickness of 0.75 inches (19.05 mm), a maximum thickness of 0.5 inches (12.7 mm), for example, 0.1 inches (2.54 mm) to 1 inch (25.4 mm), 0.1 inches (2.54 mm) to 0.75 inches (19.05 mm), 0.1 inches (2.54 mm) to 0.5 inches (12.7 mm), or 0.25 inches (6.35 mm) to 0.5 inches (12.7 mm). In the embodiment, the diameter (or widest dimension perpendicular to the axial direction) is up to 10 inches (254 mm), up to 9 inches (228.6 mm), up to 8 inches (203.2 mm), up to 7 inches (177.8 mm), up to 6 inches (152.4 mm), up to 5 inches (127 mm), up to 4 inches (101.6 mm), for example, from 4 inches (101.6 mm) to 10 inches (254 mm), but the size of the heater body can be set based on the specific application, for example, to roughly correspond to the cross-sectional size of the catalyst substrate or filter used with the heater.

[0054] Since slot 34 provides electrical insulation, the termination 46 of slot 34 corresponds to the location where the meandering path 32 bends around slot 34, and therefore represents the location where the current flow changes direction. As a result of these bends in the meandering path, more heat may be generated, and therefore, the concentration of current flow at the termination 46 is known to form a hot spot. That is, the current flow tends to concentrate along the shortest path through the bend, corresponding to the material of the heater body 30 that is directly adjacent to and / or borders the termination 46 of slot 34. Such hot spots can make these areas of the heater body 30 particularly susceptible to premature failure, fracture, cracking, bending, warping, or other degradation of mechanical or thermomechanical properties or performance, especially as the heater assembly 18 increases in the number of heating and cooling cycles during use.

[0055] Furthermore, partly due to the concentration of current flow directly through the material of the heater body 30 toward the termination 46, the material of the heater body 30 on the other side of the termination 46 (in the direction in which the slot 34 extends into the heater body 30) cools down more rapidly than both the hot spot and the rest of the heater body 30. This rapid temperature drop occurs as a result, since the current flow in the material of the heater body 30 decreases as the distance from the termination 46 toward the outer surface 36 increases.

[0056] Taking the above into consideration, and as shown in Figures 2 and 3, the meandering path 32 can be defined along a plurality of core segments 48 and a plurality of bending 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 along each pair of adjacent slots among the slots 34, while the bending region 50 includes the conductive material of the heater body 30 in the region adjacent to the end portion 46 where the meandering path 32 bends.

[0057] Examples of general regions corresponding to the core segment 48 and the bent region 50 are shown in the drawings. However, since the core segment 48 and the bent region 50 are each formed from the conductive material of the heater body 30 (for example, the core segment 48 and the bent region 50 can be integrally formed from the conductive material as part of the same structure, such as both being formed from or as part of the array of intersecting walls 40 shown), there does not need to be a clear physical demarcation or boundary between these two regions. Instead, the core segment 48 and the bent region 50 can overlap to some extent, and / or a transition may exist between them.

[0058] While it may be difficult to physically observe the transition between the core segment 48 and the bent region 50, the temperature profile of the heater body 30 can be useful for more specifically determining the location of the core segment 48 and the bent region 50. For example, if an appropriate voltage is applied across the heater body 30 to raise the temperature of the heater body to at least several hundred degrees (e.g., in the range of 700°C to 1000°C), the material of the heater body 30 within the core segment 48 will reach a substantially uniform or uniform temperature throughout the core segment 48, while the temperature within the bent region 50 will differ significantly from the temperature of the core segment 48. For example, as described above, the bends in the meandering path 32 located within the bent region 50 of the heater body 30 undesirably tend to promote the formation of both the aforementioned hot spots and rapidly cooling regions within the heater body 30 toward the outer peripheral surface 36 beyond the terminal portion 46 in the direction in which each slot extends into the heater body 30.

[0059] Furthermore, as shown throughout Figures 3 to 11, the heater body 30 includes auxiliary conductive functional sections 52 positioned in at least some of the bent regions 50. As further described herein, the auxiliary conductive functional sections 52 include additional or excess conductive material positioned in various patterns, ranges, structures, and / or regions of the heater body 30. As further described herein, it has been found that including the auxiliary conductive functional sections 52 in the bent regions 50 where the meandering path 32 bends around the termination 46 of the slot 34 can be advantageously useful in locally reducing the resistance of the heater body 30 in the bent regions 50. In this way, locally reducing the resistance of the heater body 30 within the bent regions 50 helps to distribute the current more significantly over a larger area in the bent regions 50. By distributing the current flow over a larger area (through a more conductive material), the auxiliary conductive functional section 52 helps to mitigate the formation of hot spots in the material directly adjacent to or bordering the termination 46 of the slot 34, and to reduce the temperature in the heater body 30 that decreases rapidly as the distance from the termination 46 increases toward the circumferential surface.

[0060] The auxiliary conductive functional section 52 may be made of the same or different material as the conductive material forming the base structure of the heater body 30. For example, the material of the auxiliary conductive functional section 52 may be the same or different material as the wall 40 if a honeycomb design is used for the heater body 30, or it may be the same or different material as the foam, grid, or woven fiber or wire of the embodiments described herein.

[0061] In the embodiment shown in Figure 3, the auxiliary conductive functional section 52 has a filleted or rounded corner 54 of the wall 40 directly adjacent to the end portion 46 of the slot 34, so that the end portion 46 is correspondingly rounded or tapered. In embodiments in which the heater body 30 has a honeycomb design, the end portion 46 does not need to be tapered or pointed, but can have a shape different from the regular pattern of the intersecting walls 40, or otherwise occupy only a portion of one of the cells 42 (for example, the end portion 46 may terminate in half of the cell 42, and the auxiliary conductive functional section 52 may include the remaining half which is filled with conductive material).

[0062] Figure 4 shows an embodiment in which the heater body 30 has a honeycomb design, in which the auxiliary conductive functional section 52 includes a plurality of cells 42 that are fully filled with conductive material and are in direct proximity to the terminal section 46, and these cells are indicated by reference numeral 55. Figure 5 shows an embodiment in which the auxiliary conductive functional section 52 includes a plurality of partially filled cells 42 that are in direct proximity to the terminal section 46, and these cells are indicated by reference numeral 56. Thus, the partially filled cells 56 include a channel 58 inside them to assist in further heat transfer, for example, by a fluid flow through the heater. For example, a fully filled channel as shown in Figure 4 can be used together with a partially filled cell 56 as shown and described in Figure 5. Any number of cells (e.g., more or less than the illustrated number of fully filled cells 55 and / or partially filled cells 56) or combinations of cells (e.g., different from the illustrated pattern) can also be used.

[0063] A rough schematic comparison between the heater body 30 without the auxiliary conductive functional section 52 adjacent to the end portion 46 of the slot 34 in the bending region 50 and the heater body 30 with the auxiliary conductive functional section 52 can be seen by referring to Figures 6A and 6B. More specifically, Figures 6A and 6B schematically show a dashed line representing the path that approximates the center of the current flow and thus generally represents the meandering path 32. As shown in Figure 6A without the auxiliary conductive functional section 52, consistent with the description herein, the current flow tends to concentrate at the end portion 46, as shown in Figure 6A by a dashed line representing a "pinching" close to the end portion 46. Such a concentration of current flow can result in the aforementioned hot spot at the end portion 46. In contrast, the addition of the auxiliary conductive functional section 52 shown in Figure 6B (similar to the strip of five fully filled cells 55 in the embodiment of Figure 4, the functional section 52 shown in Figure 6B) results in a broader current, thereby causing a "wider" bend around the termination section 46 shown in Figure 6B. Thus, the auxiliary conductive functional section 52 positioned at the termination section 46 may be effective in embodiments for reducing hot spots at the termination section 46 of the slot 34 where the meandering path 32 is bent to fold back itself.

[0064] It has been found that the extension of the auxiliary conductive functional section 52 not only beyond the termination 46 of the slot 34, but also at least partially along the length L of the slot (see Figure 3), can be particularly beneficial in embodiments that further assist in "guiding" current away from the termination 46. For example, Figure 7A shows one such embodiment in which the auxiliary conductive functional section 52 takes the form of several strips 60, which partially extend along the length L of the slot 34 and also extend beyond the termination 46 in the direction in which the slot 34 extends into the heater body 30, as indicated by arrows 62 in Figure 7A. More specifically, each strip 60 has several wedge-shaped sections 64 that partially fill the corresponding cells 42, which are indicated by the alphabetical subscripts "a" to "d" for ease of explanation.

[0065] If at least a portion of the auxiliary conductive functional portion 52 intersects a virtual line extending perpendicularly with respect to the direction 62 of the slot 34 from the side of the slot 34, then it can be determined whether the auxiliary conductive functional portion 52 is located at least partially along the length L of the slot 34. That is, in the case of the strip 60, both wedge-shaped portions 64a and 64b are located along the length L of the slot 34, while the wedge-shaped portions 64c and 64d are located beyond the end portion 46 in direction 62.

[0066] It has also been found that it may be even more beneficial to have at least a portion of the auxiliary conductive functional section 52 spaced away from the slot 34 at a position where the auxiliary conductive functional section 52 extends along the length of the slot 34, thereby assisting in "guiding" the current away from the termination section 46. For example, as described above, both wedge-shaped sections 64a and 64b are positioned along the length L of the slot 34. In addition, both wedge-shaped sections 64a and 64b are spaced away from the slot 34. In particular, the wedge-shaped section 64b is spaced away from the slot 34 by the full width of one cell 42, while the wedge-shaped section 64a is spaced away by approximately 1.5 cell widths. In this way, the auxiliary conductive functional section 52 in the form of a strip 60 functions to "collect" a higher density current from the corresponding core segment 48 and to "guide" this higher density current around and away from the termination section 46. The auxiliary conductive functional section 52, for example, the strip 60, can, if desired, extend from the bending region 50 into the adjacent core segment 48.

[0067] Figure 7B shows a magnified view of a single cell 42 partially filled by one of the wedge-shaped portions 64 in Figure 7A. The dashed white line is shown to facilitate the distinction between the wedge-shaped portion 64 and the wall 40 (which has a wall thickness t), but it should be noted that the wedge-shaped portion 64 can be formed integrally with the wall 40. In effect, the wedge-shaped portion 64 can be positioned as a filled or greatly filleted corner between intersecting walls 40. As shown in Figure 7B, the wedge-shaped portion 64 can extend at least partially along one or both of the dimensions of the relevant cross-section of the cell 42 partially filled by the wedge-shaped portion. The dimensions of the cell 42 are shown as X and Y in Figure 7B. In Figure 7B, the cell 42 is square and therefore X and Y are the same, but in another embodiment these dimensions may be different. In the illustrated embodiments, the wedge portion 64 extends over the entire first dimension X (in the direction 62 of the slot 34), but only partially along the second dimension Y (in the direction perpendicular to direction 62). In embodiments, the wedge portion 64 extends only partially along both dimensions X and Y. For example, in some embodiments, the wedge portion 64 does not extend over the entire distance X of the cell, but starts in the range of 25% to 75% of dimension X. It has also been shown that the wedge portion 64 can increase from a minimum width on one side (left side in Figure 7B) to a maximum width on the opposite side (right side in Figure 7B). In the embodiment, the minimum width range may be 0% to about 50% of the second dimension Y, for example 0% to 25%, or even 0% to 10%, while the maximum width range may be about 20% to about 100% of the second dimension Y, for example 20% to 80%, about 30% to about 70%, or about 40% to about 60%.

[0068] Figure 8 shows an embodiment of the auxiliary conductive functional section 52 that is substantially similar to the embodiments in Figures 7A and 7B, but includes two main differences. First, the auxiliary conductive functional section 52 in Figure 8 has a single continuous strip 66 that extends at least partially along the slot 34, on both sides of the slot 34, and completely encircles the termination 46 as well. In comparison, Figure 7A shows two strips 60 separated by one of the cells 42 beyond the termination, which include any additional material. However, each of the two strips 60 can be considered continuous in itself, as the wedge portions 64 that are continuous within the strip are in contact with the same wall 40 as the preceding wedge portion 64. Second, the auxiliary conductive functional section 52 in Figure 8 includes a wedge portion 68 that is curved or corrugated, unlike the linear inclined surface of the wedge portion 64. The wedge-shaped portion 68 can extend over a percentage range of the dimensions X and Y of the cell 42, similar to the wedge-shaped portion 64, except that it follows a nonlinear curve rather than a linear inclined surface.

[0069] While a curved or corrugated wedge-shaped portion 68 may be particularly advantageous in some embodiments for achieving a temperature drop similar to that of a linear wedge-shaped portion 64, the amount of material used is significantly reduced. The use of less material in the wedge-shaped portion 68 can provide a larger open area for fluid (e.g., exhaust) to flow through the heater body 30, and can also help reduce strain in the heater body 30 due to differences in thermal expansion or other temperature-based dimensional changes.

[0070] Figures 9A to 9F show various embodiments in which the heater body 30 has a honeycomb design and the auxiliary conductive functional section 52 has various strips of thickened walls 70 (indicated by corresponding alphabetical subscripts "a" to "f") which have a greater wall thickness than the walls 40 that extend throughout the heater body 30. Similar to the embodiments in Figures 7A to 8, the auxiliary conductive functional section 52 in the embodiments in Figures 9A to 9F includes a portion that extends at least partially along the length L of the slot 34. In particular, each embodiment in Figures 9A to 9F includes a continuous strip of thickened walls 70 that extends at least partially along the length L not only on both sides of the slot 34 but also continuously around the end portion 46. In embodiments, some or all of the corners between intersecting thickened walls 70 can be at least partially filled with filleted or wedge-shaped portions, as described with respect to wedge portions 64 and 68. In some embodiments, the thickened wall 70 is at least 25% thicker than the intersecting wall 40, at least 50% thicker than the intersecting wall 40, at least 75% thicker than the intersecting wall 40, or even at least twice as thick as the intersecting wall 40.

[0071] More specifically, Figures 9A and 9C show different patterns of strips of the thickened wall 70, indicated as thickened walls 70a, 70b, and 70c, respectively. As illustrated, the thickened walls 70a and 70b in Figures 9A and 9B may be useful for positioning the auxiliary conductive functional section 52 further away from the slot 34 (generally as described with respect to the embodiment in Figure 7A above) than the position of the thickened wall 70c in Figure 9C, which is relatively close to the side of the slot 34 along the length L of the slot 34. That is, the thickened wall 70c in Figure 9C is separated from the side of the groove 34 by approximately two cell widths, whereas the walls 70a and 70b in Figures 9A and 9B gradually increase the distance from the side of the slot 34 to a distance of four cell widths. The thickened wall 70d in Figure 9D is generally similar to the thickened wall 70a in Figure 9A, except that the wall 70d additionally has several arms 72 that extend at least partially along the length of the slot 34. The thickened wall 70e in Figure 9E is also generally similar to the thickened wall 70a, except that the heater body 30 in Figure 9E differs in that portions of the wall 40 are removed on both sides of the termination 46 to form a gap 74. This gap 74 can be particularly useful in preventing the flow of current in the material of the heater body 30 directly adjacent to the termination 46. However, the removal of the wall portion may reduce the strength of the heater body 30 in Figure 9E. Therefore, Figure 9F shows a design similar to Figure 9E, except that there are two additional diagonal walls 76 extending diagonally from the thickened wall 70f to the terminal section 46, which advantageously provides supplemental strength or support to the heater body 30 to compensate for what is lost by forming the gap 74.

[0072] Figure 10 shows an embodiment in which the auxiliary conductive functional section 52 includes a supplementary wall 78 extending across some of the cells 42. The supplementary wall 78 is arranged as in several other embodiments herein, extending at least partially along the length L of the slot 34, on both opposing sides of the slot, and completely surrounding the termination 46 as a continuous strip or path. Furthermore, a portion of the supplementary wall 78 extending at least partially along the length L of the slot 34 is also separated from the slot 34.

[0073] Figure 11 shows an embodiment in which the auxiliary conductive functional section 52 includes a thickened boundary wall 80 that extends around the termination section 46 and at least partially along the length of the slot 34. Thus, the thickened boundary wall 80 is generally similar to the filleted corner 54 in Figure 3, but in the thickened portion, it also extends below a portion of the side surface of the slot 34. For example, the thickened boundary wall 80 is at least 50% thicker than the wall 40, at least twice the thickness of the intersecting wall 40, or even at least three times the thickness of the intersecting wall 40.

[0074] It will be apparent to those skilled in the art that various modifications and changes can be made without departing from the spirit or scope of the claimed subject matter. Therefore, the subject matter of the claims should not be limited except in light of the appended claims and their equivalents.

[0075] Preferred embodiments of the present invention are described below in separate sections.

[0076] Embodiment 1 It is the heater unit: Outer surface and; Each of the multiple slots extends from the outer peripheral surface and terminates at an end within the heater body, A plurality of core segments made of a conductive material, each core segment defined between different adjacent slot pairs; A plurality of bent regions made of the conductive material, each of the bent regions being positioned around one of the end portions of the slot, and each pair of adjacent core segments being connected by the corresponding bent region among the bent regions; An auxiliary conductive functional part is provided in each of the bending regions adjacent to each of the terminal portions; It has, The plurality of slots electrically isolate each pair of adjacent core segments from one another in order to form a meandering current transmission path that extends through the conductive material in the core segments and the bending region across the heater body. Each of the auxiliary conductive functional parts locally reduces the electrical resistance of the heater body in the bending region compared to the case of the conductive material alone. The heater unit.

[0077] Embodiment 2 The heater body according to Embodiment 1, wherein each auxiliary conductive functional part has a filleted or rounded corner at the end of the slot.

[0078] Embodiment 3 The heater body according to Embodiment 1, wherein the conductive material consists of a foam, a lattice, or woven fibers, filaments, or wires that form a plurality of channels that penetrate the heater body in the axial direction.

[0079] Embodiment 4 The heater body according to Embodiment 1, wherein the conductive material is formed as an array of intersecting walls defining a plurality of cells in a honeycomb design.

[0080] Embodiment 5 The heater body according to Embodiment 4, wherein each auxiliary conductive functional part includes one or more of the cells in the bending region, which are completely filled with a supplementary conductive material.

[0081] Embodiment 6 The heater body according to Embodiment 4, wherein each auxiliary conductive functional part includes one or more cells in the bending region, at least partially filled with a supplemental conductive material.

[0082] Embodiment 7 Each auxiliary conductive functional section includes a continuous strip of supplemental conductive material, as described in Embodiment 4 of the heater body.

[0083] Embodiment 8 The heater body according to Embodiment 7, wherein the strip includes a plurality of wedge-shaped portions, each wedge-shaped portion partially filling a corresponding cell among the cells.

[0084] Embodiment 9 The heater body according to embodiment 8, wherein the wedge-shaped portion has a linear inclined surface.

[0085] Embodiment 10 The heater body according to Embodiment 8, wherein the wedge-shaped portion has a nonlinear inclined surface and is formed in a wave shape.

[0086] Embodiment 11 The heater body according to any one of embodiments 8 to 10, wherein the wedge-shaped portion increases in width across each cell from a minimum dimension of 0% to 25% of the cell width to a maximum dimension of 25% to 100% of the cell width.

[0087] Embodiment 12 The heater body according to Embodiment 4, wherein each auxiliary conductive functional section includes a continuous strip of thickened walls that are thicker than the intersecting walls.

[0088] Embodiment 13 The heater body according to embodiment 12, wherein the thickened wall includes a plurality of arms extending from the bending region toward each core segment.

[0089] Embodiment 14 The heater body according to Embodiment 4, wherein each auxiliary conductive functional part includes a thickened boundary wall that forms the boundary of the end portion of the slot.

[0090] Embodiment 15 A heater body according to any one of embodiments 1 to 14, wherein each auxiliary conductive functional part extends at least partially along the length of the slot.

[0091] Embodiment 16 The heater body according to embodiment 15, wherein each auxiliary conductive functional part extends at least partially along the length of the slot on both opposing sides of the slot.

[0092] Embodiment 17 The heater body according to Embodiment 15, wherein at least a portion of each auxiliary conductive functional part extending at least partially along the length of the slot is also separated from the slot.

[0093] Embodiment 18 The heater body according to Embodiment 17, wherein the conductive material is formed as an array of intersecting walls defining a plurality of cells in a honeycomb design, and a portion of each auxiliary conductive functional part is separated from the slot by at least the width of one cell.

[0094] Embodiment 19 The heater body according to any one of embodiments 1 to 18, wherein the auxiliary conductive functional portion extends continuously from a first core segment among the plurality of core segments, through the bending region, to a second core segment among the plurality of core segments.

[0095] Embodiment 20 A heater assembly comprising a heater body according to any one of embodiments 1 to 19, connected to electrode pairs at both ends of a meandering path.

[0096] Embodiment 21 An exhaust aftertreatment assembly comprising the heater assembly described in Embodiment 20 and aftertreatment components connected to a common housing or piping.

[0097] Embodiment 22 The exhaust aftertreatment assembly according to Embodiment 21, wherein the aftertreatment component comprises a porous ceramic honeycomb body.

[0098] Embodiment 23 The exhaust aftertreatment assembly according to Embodiment 21, wherein the heater body, the aftertreatment component, or both thereof, includes a catalytic material.

Claims

1. It is the heater unit: Outer surface and; Each of the multiple slots extends from the outer peripheral surface and terminates at an end within the heater body, A plurality of core segments made of a conductive material, each core segment defined between different adjacent slot pairs; A plurality of bent regions made of the conductive material, each of the bent regions being positioned around one of the end portions of the slot, and each pair of adjacent core segments being connected by the corresponding bent region among the bent regions; An auxiliary conductive functional part is disposed in each of the bending regions adjacent to each of the terminal portions; It has, The plurality of slots electrically isolate each pair of adjacent core segments from one another in order to form a meandering current transmission path that extends through the conductive material in the core segments and the bending region across the heater body. Each of the auxiliary conductive functional parts locally reduces the electrical resistance of the heater body in the bending region compared to the case of the conductive material alone. The conductive material is formed as an array of intersecting walls that define multiple cells in a honeycomb design. Each auxiliary conductive functional section includes a continuous strip of supplemental conductive material. The strip includes a plurality of wedge-shaped portions spaced apart from the wall defining the slot, each wedge-shaped portion partially filling a corresponding cell among the cells. The plurality of wedge-shaped portions extend at least partially along the length of the slot and are further separated from the slot as they move away from the end portion. The heater unit.

2. The heater body according to claim 1, wherein each auxiliary conductive functional part has a filleted or rounded corner at the end of the slot.

3. The heater body according to claim 1, wherein the wedge-shaped portion has a linear inclined surface.

4. The heater body according to claim 1, wherein the wedge-shaped portion is formed into a corrugated shape having a nonlinear inclined surface.

5. The heater body according to any one of claims 1 to 4, wherein the wedge-shaped portion increases in width across each cell from a minimum dimension of 0% to 25% of the cell width to a maximum dimension of 25% to 100% of the cell width.

6. The heater body according to claim 1, wherein the auxiliary conductive functional portion extends continuously from a first core segment among the plurality of core segments, through the bending region, to a second core segment among the plurality of core segments.

7. A heater assembly comprising the heater body according to claim 1, which is connected to electrode pairs at both ends of a meandering path.

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