Heating element with open cell structure

Abstract

The invention relates to a heating element having an open cell structure, comprising a body having a three-dimensional substrate having an open structure comprising openings and internal voids, cavities and / or apertures extending throughout the body. The three-dimensional substrate is provided as a grid having repeating unit cells extending in three directions. The heating element of the present invention is adapted to maximize the surface area, thereby providing an effective and efficient thermal energy transfer medium.

Description

[0001] This application is a divisional application of the Chinese application with application number 202080074037.2, filing date October 28, 2020, and title “Heating element with open cell structure”. Technical Field

[0002] The invention relates to a heating element for transferring thermal energy. Background Art

[0003] Electric heaters generally include a resistive heating element to heat a fluid or solid object. Traditionally, relatively thin metal alloy wires, strips or tubes are used as heating elements, wherein the heating effect is achieved by the passage of an electric current and the resistance of the wire or tube.

[0004] Existing heating elements have limited energy transfer efficiency, primarily due to their relatively small area-to-volume ratio. In addition, larger heating elements can be heavy and structurally weak. As a result, they are prone to deformation, sagging and creep after repeated high-temperature operation.

[0005] When heating by radiation, it is also difficult to adapt conventional heating elements to the voltage / current sources available in use and to provide uniform heating of irregular solid objects.

[0006] Therefore, there is a need for more effective and efficient heating elements for transferring thermal energy in heating devices and the like.

[0007] US 3244860 discloses a heater for gas, comprising a metal mesh resistance heating element arranged in a housing. A plurality of concentrically arranged individual mesh strips form the heating element. The gas flows through the housing and the mesh strips, thereby being heated.

[0008] US 2018 / 0274817 discloses an in-line fluid heater. The body of the heater is indirectly heated by an electrically heated heating element. The body includes an inlet port and an outlet port for the fluid to be heated. In the case where a tubular conduit extends through the body, 3D printing of aluminum is proposed as a production method for the body. Summary of the invention

[0009] An object of the present invention is to provide a heating element. The heating element can be configured for use in a heating device, a heating assembly or a heating apparatus. The heating element provides an enhanced transfer of thermal energy from the body of the heating element to a receiving phase (e.g. a fluid flowing in contact with the heating element) or to a solid body to be heated by radiation. Another specific object is to provide a heating element that provides enhanced structural and mechanical properties, in particular bending strength, in order to withstand vibrations and movements of the heating element relative to other components of the heating assembly (e.g. a surrounding or encapsulated ceramic block or other auxiliary body (optionally including additional heating wires)).

[0010] Another specific object is to provide a heating element having structural and mechanical properties that enable the heating element to withstand stresses and general physical requirements encountered in use caused by large pressure differentials, gravity and cyclic heating gradients. In particular, a specific object is to provide a high strength and lightweight heating element that is suitable for resisting deformation, sagging and creep after repeated high temperature operation.

[0011] Another object is to provide a heating element that can be configured as a main heating element or an active heating element through which electric current flows predominantly or preferentially. Another object is to provide a heating element that can be configured as a passive heating element relative to one or more auxiliary bodies through which electric current flows predominantly or preferentially, or the auxiliary body is heated by the combustion of a gas. In this embodiment, the three-dimensional matrix of the present invention can firstly provide structural support for the auxiliary body (e.g., a filament, strip, plate, or tube), and secondly, it can significantly enhance the heat transfer effect of the auxiliary body, for example by increasing the surface area of ​​the auxiliary body.

[0012] These objects are achieved by a heating element, the heating element comprising: a body, the body is a three-dimensional matrix with an open structure, the open structure defines an opening, a gap and / or a pore extending through the body. The three-dimensional matrix is ​​arranged as a grid, the grid having a repeating unit cell to define at least a portion of the body. The body comprises at least two unit cells positioned adjacent to each other in a first direction, at least two unit cells positioned adjacent to each other in a second direction, and at least two unit cells positioned adjacent to each other in a third direction. The first direction, the second direction and the third direction are arranged at an angle to each other. This configuration maximizes the surface area to volume ratio of the heating element, and thereby enhances the transfer of thermal energy.

[0013] The three-dimensional grid matrix has a regular structure. Therefore, an irregular structure (such as a foam or a nonwoven web) is not a three-dimensional grid matrix. Therefore, the unit cells of the grid of the three-dimensional matrix are regularly arranged in the body. The unit cells of the grid of the three-dimensional matrix can be symmetrically arranged in the body. In the grid of the body, each of the first direction, the second direction and the third direction that define the adjacent positions of the unit cells extends at the same angle relative to each other. That is, the angle between the first direction and the second direction is equal to the angle between the second direction and the third direction and the angle between the first direction and the third direction.

[0014] The three-dimensional matrix / open structure of the present invention is further conducive to withstanding the thermal, physical and mechanical requirements in heating devices, electric heaters, ovens, stoves, etc. The heating element of the present invention is further advantageous because it can be formed into any shape and configuration. This is achieved because it is lightweight and strong and can be manufactured by technologies such as 3D printing, additive manufacturing, etc. Due to the open structure of the grid matrix, fluids can pass through the element without the need for dedicated openings in the structure. This open structure can also structurally support solid heating elements. Therefore, this solid heating element can be designed in a new way, which is impossible without the lightweight structural support provided by the grid matrix. In addition, this grid matrix structure can be used to increase the surface area of ​​the solid heating element.

[0015] Another advantage of the open structure heating element of the present invention is the feasibility and freedom of choice of designing current and fluid flow paths of almost any configuration through the substrate when the substrate comprises an electrically conductive material when the element of the present invention is used for direct resistive heating (i.e., active heating). The element may alternatively be implemented for passive heating, i.e., in combination with at least one auxiliary body through which the current is directed to flow predominantly or preferentially relative to the three-dimensional substrate portion of the element.

[0016] A relatively dense grid matrix structure will provide higher resistance to fluid flow and lower electrical resistance than a less dense grid matrix structure. Thus, the heating element of the present invention (e.g., when formed as a 3D printed structure) can design different paths for current flow and also for fluid flow. In addition, the paths for current flow can vary in cross-sectional area, thereby providing structural areas that can differ in their respective material density, matrix pattern, type and / or shape, etc. In addition, the design of different paths for fluid flow can vary in cross-sectional area through the heating element.

[0017] This consideration applies to the main matrix portion and / or the auxiliary body of the element. Optionally, the auxiliary body (e.g., at least one thin rod, wire, strip, plate or tube) can be formed integrally with the main open structure matrix. Optionally, the auxiliary body can be a shape formed integrally with the main body, having a denser grid structure than the main body. Therefore, the grid structure of the present invention can be used as a passive reinforcement structure for an auxiliary body or auxiliary element that acts as / is the main active electrical conductor. Optionally, the auxiliary body has a lower resistivity than the main body.

[0018] Thus, the heating element may comprise an electrically conductive auxiliary body, the main body being positioned adjacent to the auxiliary body.

[0019] When the configuration of the present invention is implemented in conjunction with other components of the adjacent heating device (such as the surrounding ceramic jacket block, other heating elements or external housing / shell), the configuration of the present invention promotes the stability of the heating element through the open structure. In particular, the open structure matrix can be branched or include radial protrusions that are suitable for physically attaching or abutting potential adjacent components of the heating device. Such radial attachment can be integrally formed as a part of the configuration of the present invention. For example, such stabilizing components can include stabilizing discs, rods, blocks, fins, braces, brackets or flanges.

[0020] The open structure matrix of the present invention including a grid structure can be manufactured, for example, by additive manufacturing. The open structure matrix can include "terminals" located at opposite ends of the grid structure, which can connect the grid structure to a suitable electrical connection / conduit so as to apply voltage to the heating element. Such terminal ends can be manufactured together with the grid structure, for example, by additive manufacturing, so as to form an integral body. This is conducive to providing a structurally strong element. The heating element provided by this construction will have an open grid area and a corresponding terminal end area, which is represented by a generally denser or solid body portion, such as a layer, plate, disk or other generally solid body without the same type of openings, voids or pores of the open matrix.

[0021] According to a first aspect of the present invention, there is provided a heating element comprising: a body; the body being a three-dimensional matrix having an open structure defining openings, voids and / or pores extending through the body, as defined in claim 1 .

[0022] The heating element of the present invention may be suitable for transferring heat to a fluid by conduction or convection, or transferring heat to a solid by radiation. As can be appreciated, the heating element of the present invention is suitable for use with a variety of different energy receiving phases, including various fluids (such as gases or liquids) and solids.

[0023] The heating element may be configured to transfer heat in a heating device, a heating assembly or a heating apparatus.

[0024] A particular advantage of the heating element of the present invention when used to heat solids by radiation is that the mesh open structure can be adapted to provide a structural scaffold to structurally support and increase the strength of an auxiliary body, such as a generally denser portion or solid body portion, optionally integrally formed with the mesh main body, or a separate auxiliary body heating element positioned adjacent to the base of the present invention. That is, the open structure mesh of the present invention provides a desired stiffness and / or bending strength relative to the auxiliary body, particularly when formed into a relatively thin wire, strip, thread or tubular form or element, which form or element may have a tendency to deform over time.

[0025] The heating element with open structure discussed herein is formed as a three-dimensional grid matrix with openings and internal voids, pores, cavities, channels. This open structure is represented by different terms in this article, such as: three-dimensional / 3-dimensional structure, three-dimensional / 3-dimensional matrix, matrix grid structure, grid matrix structure, grid matrix open structure, grid matrix, grid open structure, skeleton matrix, three-dimensional matrix open structure, three-dimensional open cell structure formed as a grid. Therefore, these terms refer to the same structure.

[0026] The "three / 3D matrix" or "3D matrix" mentioned in the specification includes ordered arrays, repeating unit cell arrangement structures, and grid frameworks. That is, a three-dimensional matrix, a grid matrix, etc. is a three-dimensional regular structure having nodes and including strands extending in three dimensions between the nodes, that is, the strands connect at least some of the nodes to other nodes in three dimensions. Therefore, the three-dimensional matrix forms a body with volume. In addition, the term also includes a three-dimensional matrix with different regions of regular and orderly repeating units, which differ in any one or combination of shape, pattern, apparent material density, thickness of the matrix "strand", cross-sectional area or width, for example in a plane perpendicular to the flow of current and / or fluid. The matrix "strand" mentioned in this specification covers a main body portion that is branched or skeletal to define a network and internal pores, voids, cavities or openings. The three-dimensional strand of matrix can be considered as skeleton, branch structure or connection structure, and this skeleton, branch structure or connection structure limit regular, have certain size, shape and distribution internal pore, space or opening in specific area.Therefore, strand can comprise the structure such as line, silk thread, silk, rod, strip etc., and the unit cell structure is formed by these structures.Strand is linked up at the node of three-dimensional matrix.In other words, node is formed at the connection point between at least three strands or at least four strands or at least six strands.

[0027] As used herein, the terms "mesh" and "grid" refer to a framework of strands comprising a matrix.

[0028] Thus, the grid comprises strands.

[0029] Furthermore, the strands are interconnected in nodes to form a grid of a three-dimensional matrix.

[0030] References to a substrate having an "open" structure in the specification include a generally porous rigid body construction defining a porous or open cell heating element. As an example, where the heating element of the present invention is elongated, in a cross-sectional plane perpendicular to the longitudinal axis, the cross section includes the material forming the strands / skeleton, except for free, open or unoccupied areas referred to herein as pores, cavities, voids, etc.

[0031] The heating element of the present invention may be formed into a body in which the skeleton matrix extends from the innermost region, zone or core to the outermost surface throughout the body of the heating element.

[0032] However, the heating element of the present invention may be formed as a three-dimensional grid comprising any shape and configuration, which is preformed as an ordered array of repeating unit cells. Such a structure comprises a regular grid which may be homogeneous and comprise the same repeating unit structure throughout the heating element.

[0033] Alternatively, the heating element of the present invention may be formed of grid regions that are different from each other to define a heterogeneous grid structure. For example, the body of the heating element may include at least a first region having a first grid type and at least a second region having a second grid type that is different from the first region. Optionally, the regions of the first and second regions differ in any one or combination of the following aspects: the shape or geometry of the grid; the density of the grid, which means the weight of the grid divided by the total space of the grid; the cross-sectional area, thickness or width of the strands forming the grid; the size, shape or number / amount of openings, gaps and / or pores extending throughout the body; or the overall pattern at a specific area. Optionally, the first and second regions are positioned to extend between the respective terminal ends in the longitudinal direction of the heating element. Optionally, the first and second regions are positioned to extend across the heating element in the transverse width direction relative to the longitudinal direction extending between the respective terminal ends. Optionally, the first and second regions are positioned to extend across the heating element in the longitudinal direction and the transverse width direction relative to the longitudinal direction extending between the respective terminal ends. Optionally, the first and second regions are positioned to extend orthogonally to both the longitudinal direction and the transverse direction.

[0034] The substrate is provided as a grid having repeating unit cells to define a body having a pattern. Optionally, the pattern may be uniform across the body, with openings, voids and / or pores of substantially homogeneous (i.e., substantially equal size) size and shape throughout the body. Such a uniform body configuration may be made by additive manufacturing or other common manufacturing methods, in which the unit cells are repeated throughout the length and thickness of the body. Thus, the body may be the result of an additive manufacturing process.

[0035] Optionally, the heating element body may be elongated. That is, the heating element formed by the grid matrix may include portions that may be considered as respective longitudinal ends. The longitudinal ends may be configured as terminal ends for connection to suitable electrical conduits for conveying current through the heating element, through the main body or auxiliary body of the heating element.

[0036] Optionally, the diameter or width of one of the repeating unit elements of the substrate may be in the range of at least 0.1 mm, suitable for use in electric heaters, ovens, stoves, static or mobile heating devices, including atomizers for electronic cigarettes, etc.

[0037] Alternatively, the body may be formed as an elongated cylindrical structure.

[0038] Optionally, the heating element and in particular the body may be configured for passive or active heating. In particular, the body formed by the grid-like repeating unit cells may be provided in combination with an auxiliary body, and the auxiliary body is configured for active heating. Such an auxiliary body, which is optionally formed non-integrally with the body, may include a heating element positioned in close proximity, in contact, in partial contact or in non-contact with the three-dimensional body of the present invention.

[0039] Thus, a body in the form of a three-dimensional matrix (also referred to as a primary body) may be active in the sense that the body is directly heated by an electric current directed through the body and thereby heats the body. The body transfers its heat to the fluid. Alternatively, a body in the form of a three-dimensional matrix may be passive in the sense that the body is indirectly heated by an auxiliary body. Again, it is the body that transfers its heat to the fluid.

[0040] Where the heating element of the invention comprises an auxiliary body, the auxiliary body is preferably an active element having a lower electrical resistance than the main body. In such an arrangement, very little current will pass through the main body mesh to provide a passive configuration. In such an arrangement, the mesh body can be considered to provide primarily structural reinforcement for the auxiliary body (as the medium through which the supply current primarily flows). Secondly, the mesh body provides an increased surface area for the auxiliary body, which improves heat transfer from the auxiliary body. Optionally, the main body and the auxiliary body may be integrally formed and may be produced by the same additive manufacturing process (e.g. 3D printing).

[0041] The auxiliary body is thus active in the sense that it is heated by the electric current.The auxiliary body may be a wire, a strip, a thread or a tubular element.Alternatively, the auxiliary body may be a three-dimensional matrix of a different kind than that of the main body.

[0042] Alternatively, the body may be arranged as a core positioned within the auxiliary body. Alternatively, the body may be arranged to at least partially enclose an auxiliary body positioned at or towards the core of the heating element. Alternatively, the body may be arranged as a lateral side extension of the auxiliary body, such as to extend or protrude from one or more lateral sides. Alternatively, where the auxiliary body is elongated, the body extends all or most of the length, width or thickness of the auxiliary body, such as to provide structural support between the respective ends of the auxiliary body.

[0043] The auxiliary body can be constructed for main conduction. In this construction, when electric current flows through the auxiliary body, the three-dimensional matrix main body of the present invention is suitable for being heated by direct contact. Therefore, the three-dimensional matrix main body effectively provides the auxiliary body with increased surface area and increased bending strength. Relative to the main body, the auxiliary body can be denser or more solid, with a lower degree or no openings, gaps and / or pores extending through the main body. The auxiliary body can be formed by the same material as the main body, or the main body and the auxiliary body can include different materials. When the material is a metal alloy, this "difference" can include the relative concentrations of the various elements in the alloy, or the element composition of the alloy can be different.

[0044] Optionally, the heating element may also include an auxiliary body, which may be considered as a frame or have at least one frame portion, and the open three-dimensional body extends within and / or between the frame portions. In particular, the auxiliary body frame portion may define the end region, edge and / or corner of the structure, wherein the open matrix extends within and / or between the denser or more solid frame portion. The frame portion may be formed integrally with the body of the open unit. That is, the frame portion may be formed together with the open matrix by the same process (e.g., additive manufacturing). Optionally, the frame may be connected or attached to the body of the material of the present invention. A denser or more solid frame is conducive to providing an optional main path for the flow of current. This configuration is conducive to minimizing the voltage applied to obtain the required current. A denser or more solid frame portion may be provided at the center of the body or toward the center of the body. Optionally, the frame portion may be provided at the periphery of the heating element. Optionally, the frame may extend the entire length of the heating element together with the three-dimensional open structure of the body. The frame portion represents an auxiliary body that is generally denser or more solid relative to the open three-dimensional matrix. That is, and preferably, the frame portion has a significantly lower degree of internal voids, pores or openings, or has no internal voids, pores or openings, so as to be considered to be substantially solid. In the case where the frame portion is provided as the terminal end of the heating element, the substrate can extend between the ends. Optionally, the frame portion can extend between the ends to provide a primary path for current to flow relative to the open substrate, in which configuration the open substrate will be used for passive heating, i.e., indirectly heated by heat conduction via the frame portion. Optionally, the at least one frame portion can be arranged within a three-dimensional grid. Optionally, the heating element can include a plurality of frame portions, which represent an auxiliary body formed of a denser or more solid material that is substantially free of openings, pores and voids relative to the grid of the main body.

[0045] Thus, the auxiliary body may comprise the same material as the main body and / or may be formed integrally with the main body.

[0046] According to an embodiment, the auxiliary body may extend lengthwise together with the main body between the respective ends of the heating element.

[0047] According to an embodiment, the auxiliary body may extend in a transverse width direction or orthogonally with respect to the length of the heating element.

[0048] Alternatively, the heating element of the present invention may be manufactured by an additive manufacturing process.A number of different additive manufacturing processes suitable for use with materials of the type of the present invention may be employed.

[0049] As mentioned above, the three-dimensional grid matrix of the body provides an advantageously high surface area to volume ratio for the heating element and, in turn, provides enhanced thermal energy transfer.

[0050] According to an embodiment, the body may include a surface area to volume ratio of no greater than 95:1 (eg, 1:1 to 95:1).

[0051] According to an embodiment, the electrically conductive material may be selected from the group consisting of: an iron-chromium-aluminium alloy; a nickel-chromium alloy, a copper-nickel based alloy, an iron-nickel-chromium alloy, a nickel-iron-chromium-aluminium alloy, a ceramic material and an intermetallic material. In this way, an electrically conductive material having a resistivity suitable for providing an active heating element when an electric current flows through the three-dimensional matrix structure of the body may be provided. Furthermore, such a material is suitable for use in additive manufacturing, which then provides a suitable method for producing the body.

[0052] According to an embodiment, the conductive material may have a resistance from 0.1 to 1000 Ω mm 2 Resistivity in the range of / m.

[0053] According to an embodiment, the body may have been formed in an additive manufacturing process. That is, the body may be produced by an additive manufacturing process.

[0054] According to another aspect of the present invention, there is provided a method of manufacturing a heating element according to any one of the aspects and / or embodiments discussed herein by an additive manufacturing process.

[0055] According to another aspect of the invention, there is provided an electric heater comprising a heating element as described and claimed herein. According to another aspect of the invention, there is provided a stove or oven comprising a heating element as described and claimed herein. According to another aspect of the invention, there is provided an atomizer for an electronic cigarette having a heating element as described herein. According to another aspect of the invention, there is provided an electric cigarette comprising an atomizer as described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Specific embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0057] Figure 1 is a cross-sectional side view of an electric heater including a heating element according to an embodiment of the present invention;

[0058] Figure 2 Schematically illustrates various grid configurations forming the body of a heating element according to a particular embodiment;

[0059] Figure 3 is a perspective view of a heating element according to one embodiment, which is used to be incorporated in Figure 1 Types of electric heaters;

[0060] Figure 4is another embodiment of a heating element having a grid extending between regions of the frame;

[0061] Figure 5 is a perspective view of a heating element assembly according to a specific embodiment, the heating element assembly comprising a main body and an auxiliary body, wherein the main body is formed as a grid extending externally around a solid auxiliary body;

[0062] Figure 6 is a perspective view of another embodiment of the present invention formed as an assembly having a body formed as a grid representing a core surrounded by a generally tubular auxiliary body;

[0063] Figure 7 a and Figure 7 b schematically shows a unit cell configuration suitable for forming a mesh body by a manufacturing process such as additive manufacturing. Figure 7 a and Figure 7 b, Figure 7 a represents a face-centered cubic configuration, and Figure 7 b represents body-centered cubic structure;

[0064] Figure 7 c schematically illustrates unit cells, which are arranged adjacent to each other to form a part of a grid body;

[0065] Figure 8 is a perspective view of a heating element formed as a single body according to a specific embodiment, the single body comprising a main body grid extending between two terminal ends and a frame portion auxiliary body extending longitudinally with the grid main body and adjacent to the grid between the terminal ends;

[0066] Fig. 9 yes Figure 8 An enlarged perspective view of an end region of a heating element with the mesh body removed for illustrative purposes. DETAILED DESCRIPTION

[0067] Reference Figure 1 , the electric heater 10 includes an enclosure in the form of a tubular sheath or housing 11 which defines an interior chamber 17. The heater 10 includes a fluid inlet pipe 21 and a fluid outlet nozzle 14 with an exhaust pipe 13. A fixing flange 20 is mounted to a current feed flange 19 which in turn is coupled to an external electrical connection 18. A centering extension 22 may be part of an internal heating element which extends into the tube 16 to help stabilize the heating assembly.

[0068] The jacket block 41 is mounted in position within the chamber 17 and includes an internal cavity 15 extending generally centrally through the heater 10, aligned with the longitudinal axis 12. The elongated cavity 15 is separated from the outer housing 11 by the jacket block 41 formed of a suitable thermally insulating ceramic material. The heating element 23 is mounted within the cavity 15.

[0069] According to the present arrangement, the heating element 23 comprises a three-dimensional open cell structure formed as a grid.

[0070] The heating element 23 is generally elongated and includes a first longitudinal end 23a positioned at the outlet nozzle 14 and a second longitudinal end 23b positioned at or towards the terminal end of the fluid inlet tube 21. The heating element 23 is connected to the external electrical connection 18 through a suitable intermediate electrical conduit (not shown). Thus, a voltage can be applied to the heating element 23 through the conduit and the electrical connection 18. In use, a fluid such as a gas is supplied to the electric heater 10 via the inlet tube 21 to flow over, through and contact the three-dimensional grid 23 of the elements within the cavity 15. Since the heating element 23 is formed of an electrically resistive material, the fluid is heated as it flows from the tube 21 into contact with the heating element 23 and is discharged from the device 10 through the nozzle 14 and the discharge tube 13.

[0071] In order to maximize the efficiency and effectiveness of the heat energy transfer between the heating element 23 and the fluid flowing in the cavity 15, the heating element 23 of the present invention comprises an open three-dimensional matrix, which is provided with openings, internal voids, pores, cavities and channels, etc. extending through and defined by the mesh matrix of its body. That is, the heating element 23 of the present invention can be considered to include a solid / rigid skeleton-like structure. Compared with conventional heating elements, the mesh structure provides a greatly increased heating surface to fluid volume ratio.

[0072] refer to Figure 1 , the heating element 23 of the present invention can be formed as a regular repeating unit cell in which the openings, voids, pores include a size and shape that is generally uniform (i.e., of approximately equal size) throughout the body of the heating element. This uniform regular grid provides control over the efficiency and effectiveness of transferring thermal energy to the flowing fluid. In addition, this configuration minimizes any thermal gradients across the heating element in the longitudinal axial direction and in the radial direction relative to the axis 12. As can be appreciated and as Figure 2 As shown, the relative shape, size, and overall dimensions of the grid can be implemented according to various different specific embodiments.

[0073] The honeycomb opening structure of the heating element 23 of the present invention can be manufactured by the following technology, such as additive manufacturing and computer model-based engineering manufacturing methods. Such technology is suitable for providing a repeating unit cell structure in which the body 25 of the heating element 23 forms a skeleton-like frame defining the opening 26 and the internal cavity 27.

[0074] Figure 2 Schematically illustrated are various different grid configurations of the body 25 forming the heating element 23. More specifically, the body 25 comprises at least a first region 60 having a first grid type and at least a second region 62 having a second grid type different from the first region 60.

[0075] In these embodiments, the body 25 includes six different regions 60-70. The first region 60 and the other two regions 64, 68 have a first grid type. The remaining three regions have different grid types. As already mentioned, the second region 62 has a second grid type. The third region 66 has a third grid type, and the fourth region 70 has a fourth grid type. In this way, for example, the three regions 60, 64, 68 with the first grid type can be arranged adjacent to an auxiliary body (not shown) that is electrically heated. The first grid type can provide a favorable heat transfer from the auxiliary body to the body 25, while the second, third and fourth regions 62, 66, 70 can provide the best heat transfer for the fluid passing through the body 25. Optionally, the second, third and fourth regions 62, 66, 70 can provide different pressure drops to the fluid passing through these regions, for example, the highest pressure drop of these regions can be provided by the second region 62, the third region 66 provides a medium pressure drop, and the fourth region 70 provides the lowest pressure drop. According to an alternative embodiment, all six regions 60-70 of the body 25 may have different grid types. According to a further embodiment, the regions 60-70 of the body 25 may have only the first and second grid types.

[0076] refer to Figure 3 , the heating element 23 can be formed as a hollow cylinder in which the grid of the main body 25 defines the wall of the cylinder, which has an opening 26 and an internal void 27. Specifically, the grid cylinder is both hollow inside, defined by the cylinder wall, and the wall of the cylinder is also open through the opening 26 and the internal void 27. The wall of the cylinder comprises a three-dimensional grid matrix structure. The first and second longitudinal end portions 30a, 30b of the heating element 23 are provided as solid disks. The end portions 30a, 30b can be formed integrally with the main body 25, or can be welded or attached to the main body 25. The first and second connections 28, 29 extend axially from each of the corresponding heating element end portions 30a, 30b. Therefore, as shown in reference Figure 1As described, an electric current can be applied through the heating element 23. Due to the increased contact surface area between the heating element 23 and the flowing fluid caused by the three-dimensional open grid structure, the fluid is effectively and efficiently heated relative to conventional solid heating elements. The size and shape of the internal voids, pores and cavities defined by the skeleton structure can be variable to achieve a desired global surface area / total surface area, and thereby affect the flow rate and path of the fluid flowing through the heating element 23.

[0077] according to Figure 3 In a further embodiment of the embodiment of the present invention, the body 25 may extend throughout the cylinder as a grid extending from the axial center to the outer surface of the cylinder. Figure 3 As in the embodiment of the invention, the current will then pass through the mesh body 25, which will be configured to be "active" to provide a main body through which the current passes between the terminal ends. In this embodiment, the fluid preferably flows through the body, for example transversely to the axial extension.

[0078] according to Figure 3 In another embodiment of the arrangement structure, an auxiliary body (such as a solid rod, strip or wire (not shown) formed of the same material or a different suitable material as the mesh body 25 can extend axially and internally within the mesh body 25 between the terminal ends 30a, 30b. In this arrangement structure, the auxiliary body provides the main current flow path and is therefore considered "active", while the mesh body 25 can be considered to provide structural reinforcement of the auxiliary body and will be considered "passive" so as to indirectly provide heat transfer from the current via the auxiliary body. The mesh body provides increased surface area for the auxiliary body, which effectively increases heat transfer from the auxiliary body.

[0079] According to a specific embodiment, the heating element 23 may extend continuously from the axial center to the radially outermost surface area (radially farthest from the axis 12). Figure 3 As shown and discussed above, the heating element 23 can be macroscopically formed as a hollow body in which the grid structure of the body 25 can define the walls of the cylinder. According to embodiments, the fluid can be introduced at the center and / or outer region of the cylinder and / or directed to flow through the entire area of ​​the heating element 23, including the inner hole and the outer surface. Optionally, based on Figure 3 Various embodiments of and other embodiments described herein may be constructed and operated as a radiating element to radiate thermal energy in response to electrical current flowing directly or indirectly through body 25 .

[0080] refer to Figure 4Another embodiment of the heating element of the present invention is described. According to this other embodiment, the heating element is formed as an assembly including a frame portion 32, within which the grid of the body 25 having an open three-dimensional structure extends. The frame portion 32 is an auxiliary body. The frame 32 includes edge struts 33 extending in length and transverse braces 34 extending in width. The frame 32 also includes a first end 31a and a second end 31b in the lengthwise direction. The edge struts 33 extending in length and the transverse braces 34 define an opening 35, within which the grid body 25 extends. Suitable terminal connections 28, 29 ( Figure 4 ) may be coupled to the first and second longitudinal ends 31a, 31b to allow voltage to be applied to the heating element 23 and current to pass through the heating element 23. Figure 4 In the embodiment of the invention, the current mainly flows through the frame 32, i.e. through the auxiliary body, and in particular the solid longitudinally extending support struts 33. However, some current will / can flow through the grid body 25. In this way, the grid body 25 can generate heat due to the flow of current and / or be heated by heat conduction via direct contact with the frame 32, or by radiation from the frame 32. This arrangement structure can be beneficial to minimize any risk of short circuit or unstable current flow caused by operation at high voltage. That is, by introducing the frame portion 32, the current is facilitated to flow through the heating element 23 relative to the heating element of the grid body 25 with only a higher resistance, and the applied voltage can therefore be reduced.

[0081] Conventionally, the heating element may be formed by a resistive cylindrical rod. Figure 4 The edge struts 33 can be considered as four quarters of such a cylindrical rod. Due to the spatial separation of the struts 33, the structural strength of the heating element is enhanced compared to a conventional cylindrical rod. However, the cross-sectional area of ​​the struts 33 is the same as that of the cylindrical rod. Therefore, the overall resistance of the struts 33 remains the same as that of the rod, while the structural strength of the heating element is greatly increased. At the same time, the heating effect is also maintained. As can be understood, Figure 4 The body 25 of the arrangement is considered to be "passive" (not the main current path), while the support 33 is "active". In such an embodiment, the body 25 provides further structural reinforcement to the support 33, as well as an increased heating surface in contact with the fluid passing through the heating element 23.

[0082] refer to Figure 5Another embodiment is described in which the grid body is formed as a cylindrical hollow tube. The auxiliary body 37 extends through the inner elongated hole 36 defined by the cylindrical wall formed by the main body 25. The auxiliary body 37 can be, for example, a wire, a rod or a tube. The auxiliary body 37 comprises a non-porous, more dense or solid material, which is particularly suitable as a component suitable for use as a heating element. According to Figure 5 In an embodiment, the auxiliary body 37 is positioned within the hole 36 and may or may not be in direct contact with the inwardly facing surface area of ​​the main body 25. According to another arrangement structure, the main body 25 and the auxiliary body 37 can be provided in a direct contact manner and can also be formed integrally. In use, a voltage can be applied directly to the auxiliary body 37 to act as an active electrical conductor. Although in some embodiments, the main body 25 is not suitable for direct current flow and is considered to be passive, some kind of conduction can occur through the main body 25. In any case, when the auxiliary body 37 is heated by the applied voltage, the main body 25 can be heated by direct contact, radiation and / or conduction.

[0083] The heating element of the present invention is suitable for use as a conductive heating element in which a fluid is directed to flow through a body 25, which functions in an active or passive mode. In addition, the fluid may flow through an auxiliary body 37, such as when the auxiliary body is a tube. Alternatively, the heating element of the present invention may be used as a radiator, for example to transfer thermal energy to an adjacent or neighboring solid / matter. When operating as a conductive heating element, the fluid flowing in contact with the body 25 is allowed to flow through and within the described body grid for efficient and effective thermal energy transfer. Figure 5 In the arrangement structure, the grid body 25 forms a sleeve or sheath to surround the conductive auxiliary body 37 and provide structural reinforcement and increased surface area.

[0084] according to Figure 6 In another embodiment shown, the mesh body 25 can be formed as the core of the heating element assembly, similar to Figure 5 Embodiment with auxiliary body 37. However, according to Figure 6 In the embodiment of the invention, the auxiliary body 37 is configured as a hollow elongated cylinder or tubular body, in which the main body 25 extends through the central inner hole 40 of the auxiliary body 37. Figure 5 As described, voltage may be applied directly to the auxiliary body 37, which provides direct or indirect heating of the main body 25 by direct contact and / or conduction. Fluid may be introduced into the central bore 40, as described with reference to Figure 1As described in the electric heater of . In such an embodiment, the main body 25 provides a high surface to volume ratio relative to the "empty" auxiliary body. The main body 25 also provides structural reinforcement to the auxiliary body 37. In addition, the main body 25 causes the fluid flowing through the grid to form a turbulent flow, which leads to improved heating efficiency.

[0085] The substrate (ie, body 25 ) includes at least one electrically conductive material.

[0086] The three-dimensional mesh body 25 of the present invention can be formed of any conventional material designed to be used as a heating element. Such materials are generally considered to be resistive materials and are resistant to high temperature creep and corrosion, oxidation and carbonization.

[0087] Such conductive material may be selected from the group consisting of: iron-chromium-aluminum alloy, nickel-chromium alloy, copper-nickel-based alloy, iron-nickel-chromium alloy, nickel-iron-chromium-aluminum alloy, ceramic material and intermetallic material. For example, iron-chromium-aluminum alloy will provide corrosion resistance and high temperature creep strength. Moreover, nickel-chromium alloy and iron-nickel-chromium alloy will provide corrosion resistance as well as high temperature mechanical strength and good machinability. In addition, copper-nickel-based alloy will provide good thermal conductivity and good wet corrosion performance. In addition, iron-nickel-chromium-aluminum alloy will provide overall mechanical strength, corrosion resistance and metal dust resistance. Ceramic material or intermetallic material will provide stability at high temperatures above 1300°C.

[0088] The open cell three-dimensional structure of the present invention provides a structure that further helps to enhance the physical and mechanical strength of the heating element and / or increase the heating area of ​​the heating element. Due to the lightweight and structurally strong grid body 25, the heating element of the present invention can be formed according to an unlimited number of high-strength structures, which have one or more repeating unit geometries to define an ordered grid. In particular, the open cell three-dimensional structure of the present invention may include different regions on the repeating unit structure, which in turn provide regions that provide different structural support to the auxiliary body and / or provide different current paths with different resistances, and thus provide different amplitudes of energy transfer via conduction and / or radiation. In particular, the bending strength of the heating element of the present invention can be enhanced relative to conventional solid heating elements. In addition, the open structure can facilitate the attachment of position stabilizing components, rods, braces or flanges to mount and / or fix the heating element 23 in Figure 1 According to a further embodiment, the grid structure can be designed to include a positioning support protrusion, which is integrally formed as part of the body 25 and extends radially outward from the axis 12 toward the jacket block 41 and / or the outer shell 11 and contacts the jacket block 41 and / or the outer shell 11. Such a protrusion can be attached to a suitable mounting location to positionally stabilize the heating element 23 in a suitable position.

[0089] The three-dimensional open structure can be designed to achieve a desired surface area contact with the volume of the flowing fluid. Based on the unit cell of the mesh body 25 (see below), this surface to volume ratio can be defined as the ratio of the total surface area in the unit cell to the total volume of the solid portion of the unit cell, i.e., the surface area to volume ratio. In other words, the relationship between the surface area of ​​the strands 45 and nodes of the mesh and the volume of the strands and nodes. According to one embodiment, the surface area to volume ratio is not greater than 95:1, such as 1:1 to 95:1.

[0090] This arrangement structure of the heating element 23 may be provided as a single body 25 having a single repeating unit cell or a region of different unit cells, and / or may be provided as an assembly having the body 25 combined with the auxiliary body 37. In particular, the heating element 23 may be formed as a body 25 which is as follows. Figure 2 and Figure 3 The continuous skeleton-like framework described, reference Figure 4 The frame structure / assembly shown and described, or with reference to Figure 5 and Figure 6 A multi-component assembly is described.

[0091] refer to Figure 7 a and Figure 7 b. The body 25 can be considered to be formed of repeating unit cells, each unit being formed of solid strands 45 that are joined or branched to define a three-dimensional matrix. The strands 45 are joined at nodes to form a three-dimensional matrix. The body 25 can include a single type of unit cell repeated over the entire volume of the grid, or can include a variety of different unit cell geometries to form different regions having different surface area to volume ratios and, therefore, different sizes, shapes, and multiplicities of internal cavities / pores 27, such as, for example, those described above with reference to Figure 2 The first and second regions 60, 62 are discussed. Figure 7 a unit cell configuration, the body 25 may be formed of, for example, face-centered cubic (fcc) unit cells, or refer to Figure 7 b. The body 25 may be formed of body-centered cubic (bcc) cells, or a combination thereof. The unit cell may have a diameter or width of at least 0.1 mm. The strand 45 may have a diameter of at least 0.05 mm.

[0092] According to some embodiments, the mesh may include strands 45 having a diameter or average diameter greater than 0.05 mm, for example 0.05 mm to 4 mm. The diameter and average diameter of strands 45 are measured perpendicular to the longitudinal extension of strands 45. The average diameter is the average diameter if strands 45 do not have a circular cross section.

[0093] Figure 7 c shows a plurality of unit cells 72 of a portion of the main body 25 of the heating element. Each unit cell 72 is schematically shown as a cube and may be a combination of Figure 7 a and Figure 7 b. However, the unit cell 72 is not limited to the embodiment shown, but may have any suitable internal strand structure and any suitable other external shape, such as, for example, a tetrahedral shape.

[0094] The unit cells 72 are arranged adjacent to each other in three dimensions, that is, the strands of adjacent unit cells 72 share nodes. More specifically, at the corners of each unit cell 72, the strands from adjacent unit cells 72 are connected to each other and thereby form nodes. Because each unit cell 72 (except at the outer surface of the body 25) is surrounded by other unit cells 72, the unit cells are positioned adjacent to each other in three dimensions. Therefore, the body 25 includes at least two unit cells 72, 72' positioned adjacent to each other in the first direction d1, at least two unit cells 72, 72" positioned adjacent to each other in the second direction d2, and at least two unit cells 72, 72"' positioned adjacent to each other in the third direction d3, wherein the first direction d1, the second direction d2, and the third direction d3 are arranged to be at an angle to each other. For example, as shown in the figure, if the unit cell 72 has a cubic shape, the three directions d1, d2, d3 are orthogonal, and if the unit cell 72 has a tetrahedral shape, the three directions extend at an angle of 120 degrees to each other.

[0095] refer to Figure 8 Another embodiment of the heating element is described. According to this embodiment, the grid body 25 extends axially between two terminal ends 46a, 46b. Each terminal end 46a, 46b is formed as a solid auxiliary body formed of the same material as the material forming the grid 25. A frame portion 47 contained in the auxiliary body extends axially between the terminal ends 46a, 46b in close proximity to the grid body 25. The frame portion 47, the terminal ends 46a, 46b and the body 25 are preferably formed integrally by a process such as additive manufacturing. The frame portion 47 is provided with a slot 48 to change the current flow characteristics, in particular to change the resistance of the frame portion 47. In this configuration, the body 25 provides structural support for the frame portion 47, wherein the body 25 is considered passive and the frame portion 47 is considered active as the main current flow path. Therefore, the body 25 provides thermal energy transfer, which is indirectly provided by the current passing mainly through the active heating element (i.e., the frame portion 47).

[0096] Fig. 9 yes Figure 82 is an enlarged end view of a heating element with the grid body removed for ease of illustration. As shown, the terminal end 46a is formed by relatively short plates that are positioned orthogonal to the elongated heating element (i.e., the body 25) and orthogonal to the active current frame portion 47. In a plane perpendicular to the direction of current flow between the terminal ends 46a, 46b, the terminal ends 46a, 46b include a much larger cross-sectional area than the frame portion 47 or the body 25. Therefore, the larger cross-sectional dimensions of the terminal ends 46a, 46b prevent them from radiating heat. The cross-sectional area of ​​the grid body 25 is relatively small so that only a negligible current will pass through the grid of the body 25. Therefore, the grid body 25 is configured as a passive component. As shown in FIG. Fig. 9 As shown, the cross-sectional area of ​​the frame portion 47 is smaller than the terminal ends 46a, 46b to provide a higher resistivity and, in turn, a greater heating effect. Figure 8 and Fig. 9 As shown in the example of FIG. 4 , the frame portion 47 includes a tortuous path extending lengthwise between the terminal ends 46 a , 46 b via the slot 48 .

[0097] As will be appreciated, the frame portion 47 includes a wider current flow path region 49 relative to a narrower flow path region 50. Therefore, the resistivity in the narrow region 50 will be greater to provide increased thermal energy transfer. In this way, the active frame portion 47 is provided with regions 49, 50 providing different heating effects along its length (between the terminal ends 46a, 46b), which can be advantageous in providing different heating zones within the heating device. This arrangement can be used to heat irregular solid objects in order to obtain uniform heating of the irregular object, for example by differentially heating different zones / regions of the irregular object.

[0098] According to a specific embodiment, the terminal ends 46a, 46b may also have different cross-sectional areas in both the transverse width direction and the longitudinal direction. For example, the cross-sectional area in a plane perpendicular to the current flow direction (i.e., between the terminal ends 46a, 46b) may be tapered so as to decrease in a direction outward from the grid body 25 and toward the outer casing of the heating device.

[0099] With reference to the above summary of the invention and detailed description of preferred embodiments, a list of sub-items related to the present invention is presented:

[0100] - Item 1. A heating element in a heating device, heating assembly or heating apparatus, the heating element comprising: ο Subject; o The body is a three-dimensional matrix having an open structure that defines openings, voids and / or pores extending through the body.

[0101] - Item 2. The heating element according to item 1, wherein the substrate is provided as a grid having repeating unit cells to define a body having a pattern.

[0102] - Item 3. A heating element according to Item 2, wherein the pattern is uniform and the body comprises openings, voids and / or pores having a size and shape that is substantially homogeneous throughout the body.

[0103] - Item 4. The heating element according to item 1 or 2, the body comprising at least a first region having a first grid type and at least a second region having a second grid type different from the first region.

[0104] - Item 5. The heating element according to Item 4, wherein the first region and the second region differ in any one or a combination of the following aspects: - the shape or geometry of the grid; - density of the grid; - the cross-sectional area, thickness or width of the strands forming the grid; - The size, shape or number of openings, voids and / or pores extending throughout the body.

[0105] - Item 6. A heating element according to item 4 or 5, wherein the first region and the second region are positioned to extend across the heating element in a longitudinal direction and / or a transverse direction relative to a longitudinal direction extending between respective terminal ends.

[0106] - Item 7. A heating element according to any preceding item, wherein the substrate comprises a corrugated, skeleton or cage-like frame or structure.

[0107] - Item 8. The heating element according to any of the preceding items, wherein the substrate comprises at least one electrically conductive material.

[0108] - Item 9. A heating element according to item 6, wherein the body extends radially from the center of the heating element to the outer surface.

[0109] - Item 10. A heating element according to any of the preceding items, comprising an electrically conductive auxiliary body, the main body being positioned adjacent to the auxiliary body.

[0110] - Item 11. The heating element according to Item 10, wherein the auxiliary body comprises the same material as the main body and / or is formed integrally with the main body.

[0111] - Item 12. A heating element according to Item 10 or 11, wherein the auxiliary body is denser or more solid than the main body, having a lower degree or no openings, voids and / or pores extending through the main body.

[0112] - Item 13. The heating element according to any one of Items 10 to 12, wherein the auxiliary body together with the main body extends lengthwise between the respective ends of the heating element.

[0113] - Item 14. The heating element according to any one of Items 10 to 13, wherein the auxiliary body extends in a transverse width direction or orthogonally with respect to the length of the heating element.

[0114] - Item 15. The heating element according to any one of items 10 to 14, wherein the auxiliary body comprises a uniform or variable cross-sectional area, width or thickness.

[0115] - Item 16. A method for manufacturing a heating element as described in any of the preceding items by an additive manufacturing process.

Claims

1. A heating element (23), comprising: Subject (25); The body (25) is a three-dimensional matrix having an open structure defining openings, voids and / or pores extending through the body (25), wherein The three-dimensional matrix is ​​provided as a grid having repeating unit cells (72) to define at least a portion of the body (25), wherein The body (25) includes at least two unit cells (72, 72') positioned adjacent to each other in a first direction (d1), at least two unit cells (72, 72") positioned adjacent to each other in a second direction (d2), and at least two unit cells (72, 72''') positioned adjacent to each other in a third direction (d3), and wherein The first direction, the second direction and the third direction (d1, d2, d3) are arranged at an angle to each other.

2. The heating element of claim 1, wherein the grid comprises wire strands (45).

3. The heating element according to claim 2, wherein the strands (45) are connected to each other in nodes to form the grid of the three-dimensional matrix.

4. A heating element (23) according to any of the preceding claims, wherein the repeating unit cells (72) defining the body (25) have a pattern, and the pattern is uniform, and the body (25) includes openings, voids and / or pores having a substantially homogeneous size and shape throughout the body (25).

5. The heating element (23) according to any of claims 1-3, the body (25) comprising at least a first region (60) having a first grid type and at least a second region (62) having a second grid type different from the first region (60).

6. The heating element (23) of claim 5, wherein the first region (60) and the second region (62) differ in any one or combination of the following: the shape or geometry of the grid; the density of the grid; the cross-sectional area, thickness or width of the strands forming the grid; The size, shape or number of openings, voids and / or pores extending throughout the body (25).

7. A heating element (23) according to claim 5 or 6, wherein the first region (60) and the second region (62) are positioned to extend across the heating element in a longitudinal direction and / or a transverse width direction relative to a longitudinal direction extending between respective terminal ends.

8. The heating element (23) according to any of the preceding claims, wherein the base body comprises at least one electrically conductive material.

9. The heating element (23) according to claim 8, wherein the electrically conductive material is selected from the group consisting of: iron-chromium-aluminum alloys, nickel-chromium alloys, copper-nickel based alloys, iron-nickel-chromium alloys, nickel-iron-chromium-aluminum alloys, ceramic materials and intermetallic materials.

10. The heating element (23) according to claim 8 or 9, wherein the resistivity of the conductive material is from 0.1 to 1000 Ωmm 2 / m range.

11. A heating element (23) according to any one of the preceding claims, the body comprising a surface area to volume ratio of not more than 95:1, such as from 1:1 to 95:

1.

12. The heating element (23) according to any of the preceding claims, wherein the grid comprises strands (45) having a diameter or average diameter greater than 0.05 mm, for example 0.05 mm to 4 mm.

13. The heating element (23) according to any of the preceding claims, wherein the body is the result of an additive manufacturing process.

14. The heating element (23) according to any of the preceding claims, comprising an electrically conductive auxiliary body, the main body being located adjacent to the auxiliary body.

15. The heating element (23) according to claim 14, wherein the auxiliary body comprises the same material as the main body and / or is formed integrally with the main body.

16. A heating element (23) according to claim 14 or 15, wherein the auxiliary body is denser or more solid relative to the main body and has a lower degree or no openings, voids and / or pores extending through the main body.

17. The heating element (23) according to any one of claims 14 to 16, wherein the auxiliary body together with the main body extends lengthwise between the respective ends of the heating element.

18. The heating element (23) according to any one of claims 14 to 16, wherein the auxiliary body extends in a transverse width direction or orthogonally to the length of the heating element.

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