Abstract
An elongate metallic heater element is provided for an aerosol-generating device, the heater element extending between proximal and distal ends, the proximal end configured for mounting to the device for electrical communication with the device, the heater element including either or both of: a plurality of surface notches formed on a surface of the heater element, and a plurality of sub-surface cavities defined beneath the surface of the heater element, at least some of the plurality of surface notches and the sub-surface cavities of the heater element are provided in an inner region of the heater element extending between the proximal end and 33% of a length of the heater element relative to the proximal end, and in which at least 40% by volume of all of the plurality of surface notches and the sub-surface cavities of the heater element are provided in the inner region.
Claims
1-15. (canceled)
16. An elongate metallic heater element for an aerosol-generating device, the elongate metallic heater element extending between a proximal end and a distal end, the proximal end configured for mounting to the aerosol-generating device for electrical communication with the aerosol-generating device, wherein the elongate metallic heater element comprises either or both of: a plurality of surface notches formed on a surface of the elongate metallic heater element, and a plurality of sub-surface cavities defined beneath the surface of the elongate metallic heater element, wherein at least some of the plurality of surface notches and the plurality of sub-surface cavities of the elongate metallic heater element are provided in an inner region of the elongate metallic heater element, the inner region extending between the proximal end and 33% of a length of the elongate metallic heater element relative to the proximal end, and wherein at least 40% by volume, or at least 50% by volume, or at least 60% by volume, or at least 70% by volume, or at least 80% by volume of all of the plurality of surface notches and the plurality of sub-surface cavities of the elongate metallic heater element are provided in the inner region.
17. The elongate metallic heater element according to claim 16, wherein the plurality of surface notches and the plurality of sub-surface cavities of the elongate metallic heater element occupy a cumulative volume of between 15% to 30% of a volume of a corresponding heater element free of any such notches and cavities.
18. The elongate metallic heater element according to claim 16, wherein the plurality of surface notches and the plurality of sub-surface cavities of the elongate metallic heater element occupy a cumulative volume of between 17% to 26% of a volume of a corresponding heater element free of any such notches and cavities.
19. The elongate metallic heater element according to claim 16, further comprising a plurality of through-holes extending through a thickness of the elongate metallic heater element.
20. The elongate metallic heater element according to claim 16, wherein the plurality of surface notches and the plurality of sub-surface cavities of the elongate metallic heater element are formed to define one or more honeycomb arrangements.
21. The elongate metallic heater element according to claim 16, wherein the elongate metallic heater element comprises the plurality of surface notches and is free of any sub-surface cavities.
22. The elongate metallic heater element according to claim 16, wherein the elongate metallic heater element comprises the plurality of sub-surface cavities and is free of any surface notches.
23. The elongate metallic heater element according to claim 16, wherein the surface notches and sub-surface cavities of the inner region extend laterally across at least 90%, or at least 95%, of a lateral width of the elongate metallic heater element.
24. The elongate metallic heater element according to claim 16, wherein all of the plurality of surface notches and the plurality of sub-surface cavities of the elongate metallic heater element are provided in the inner region of the elongate metallic heater element.
25. The elongate metallic heater element according to claim 16, wherein some of the plurality of surface notches and the plurality of sub-surface cavities of the elongate metallic heater element are provided in a middle region of the elongate metallic heater element, the middle region extending between 33% and 90% of a length of the elongate metallic heater element relative to the proximal end.
26. The elongate metallic heater element according to claim 16, wherein the elongate metallic heater element extends along a longitudinal axis and laterally outwards from the longitudinal axis to define a blade having opposed first and second elongate surfaces.
27. The elongate metallic heater element according to claim 26, further comprising: a resistive heating track arranged on the first elongate surface; and a plurality of the surface notches on the second elongate surface, wherein the surface notches on the second elongate surface form at least 80% by volume of all of the plurality of surface notches of the elongate metallic heater element.
28. The elongate metallic heater element according to claim 26, wherein the plurality of surface notches and the plurality of sub-surface cavities of the elongate metallic heater element are arranged in one or more laterally-symmetric groups.
29. An aerosol-generating device configured to receive an aerosol-forming substrate, the aerosol-generating device comprising: an elongate metallic heater element according to claim 16; and a power source, wherein the proximal end of the elongate metallic heater element is mounted to a mounting location of the aerosol-generating device, and the power source is in electrical communication with the elongate metallic heater element so as to, in use, resistively heat the elongate metallic heater element.
30. The aerosol-generating device according to claim 29, wherein the aerosol-generating device is configured such that, in use with an aerosol-forming substrate received in the aerosol-generating device, the elongate metallic heater element extends within the aerosol-forming substrate so as to heat the aerosol-forming substrate and generate an inhalable aerosol therefrom.
Description
[0080] FIG. 1 is a schematic view of the components of an aerosol-delivery system.
[0081] FIG. 2a is a perspective view from above of a heater element used in an aerosol-generating device of the aerosol-delivery system of FIG. 1, in which a plurality of surface notches are defined on a surface of the heater element.
[0082] FIG. 2b is a perspective view from below of the heater element of FIG. 2a.
[0083] FIG. 3a is a detail plan view of a portion of the upper surface of an exemplary heater element in accordance with the present disclosure, in which the heater element is provided with an arrangement of surface notches which are circular in plan and extend into the upper surface of the heater element to form notches which are part-spherical in form.
[0084] FIG. 3b is a sectional view along section B-B of the heater element portion of FIG. 3a. FIG. 4a is a detail plan view of the upper surface of a portion of another exemplary heater element in accordance with the present disclosure, in which the heater element is provided with an arrangement of surface notches which are circular in plan with a cylindrical bore extending into the upper surface of the heater element.
[0085] FIG. 4b is a sectional view along section C-C of the heater element portion of FIG. 4a, showing how the cylindrical bore of each surface notch extends into the upper surface of the heater element.
[0086] FIG. 5a is a detail plan view of the upper surface of a portion of another exemplary heater element in accordance with the present disclosure, in which the heater element is provided with an arrangement of surface notches which are hexagonal in plan with a hexagonal bore extending into the upper surface of the heater element.
[0087] FIG. 5b is a sectional view along section D-D of the heater element portion of FIG. 5a, showing how the hexagonal bore of each surface notch extends into the upper surface of the heater element.
[0088] FIG. 6a is a detail plan view of the upper surface of a portion of another exemplary heater element in accordance with the present disclosure, in which the heater element is provided with an arrangement of surface notches which are hexagonal in plan with a hexagonal bore extending into the upper surface of the heater element.
[0089] FIG. 6b is a detail plan view of the lower surface of the portion of the heater element of FIG. 6a, in which both a resistive heating track and an arrangement of surface notches which are hexagonal in plan are provided on the lower surface of the heater element.
[0090] FIG. 6c is a sectional view along section E-E of the heater element portion of FIGS. 6a and 6b, showing how the hexagonal bore of the surface notches extends into both the upper and lower surfaces of the heater element.
[0091] FIG. 7a is a detail plan view of the upper surface of a portion of another exemplary heater element in accordance with the present disclosure, in which the heater element is provided with an arrangement of sub-surface cavities which are spherical in form.
[0092] FIG. 7b is a sectional view along section F-F of the heater element portion of FIG. 7a, showing how the cavities are arranged in a single sub-surface layer embedded within the heater element.
[0093] FIG. 8 is a sectional view of a variation to the heater element of FIGS. 7a and 7b (along section F-F), in which the heater element is provided with an arrangement of three layers of sub-surface cavities embedded within the heater element.
[0094] FIG. 9 is a sectional view of another heater element, being a combination of the examples of FIGS. 5a,b and 7a,b in that an arrangement of surface notches which are hexagonal in plan is provided on an upper surface of the heater element and an arrangement of spherical sub-surface cavities is provided as a single layer embedded within the heater element.
[0095] FIG. 10 is a perspective view of five different heater elements, each having different arrangements of surface notches.
[0096] FIG. 11 is a schematic view of a machining assembly for manufacturing multiple heater elements from a sheet of metallic substrate.
[0097] FIG. 1 is a schematic view of an aerosol-delivery system 10. The aerosol-generating system 10 is a smoking system for generating an inhalable aerosol. The system 10 is formed of a combination of an aerosol-generating device 20 and an aerosol-generating article 30.
[0098] The aerosol-generating device 20 has an elongate housing 21 formed of a polymer material. The elongate housing 21 contains a power source 22, a controller 23 and a mounting location 24. A metallic heater element 40 is detachably mounted to the mounting location 24 by use of a push-fit connection. The heater element 40 is formed of a metallic substrate 41 and has a resistive heating track 42 overlaid on a surface of the substrate (see, for example, FIG. 2b). The structure of the heater element 40 is described in more detail in subsequent paragraphs. The heater element 40 is mounted to the mounting location 24 so that the resistive heating track 42 is electrically coupled to the mounting location. An access opening 25 is provided at one end of the elongate housing 21. A blind cavity 26 extends from the access opening 25 into the interior of the elongate housing 21. The heater element 40 extends from a closed end 27 of the blind cavity 26 towards the access opening 25.
[0099] The aerosol-generating article 30 is cylindrical in form and extends between a distal end 31 and a mouth end 32. The aerosol-generating article 30 has a wrapper 33. The wrapper 33 is in the form of a cigarette paper. A plug of aerosol-forming substrate 34, a hollow acetate tube 35, a tubular spacer element 36 and a mouthpiece filter 37 are co-axially and sequentially arranged within the wrapper 33. The aerosol-generating article 30 is received within the blind cavity 26 such that the heater element 40 inserts within the plug of aerosol-forming substrate 34.
[0100] For the aerosol-generating device 20, the power source 22 is coupled to the controller 23 to provide power thereto. For the example shown, the power source 22 is a rechargeable lithium ion battery. The controller 23 is coupled to the mounting location 24 to provide electric current to the mounting location 24 and thereby to the resistive heating track 42 of the heater element 40. The controller 23 is in the form of control electronics and incorporates a memory module 23a. The memory module 23a contains instructions accessible by a processor (not shown) of the controller 23 to control the supply of electric current to the resistive heating track 42 of the heater element 40. Electric current fed from the controller 23 to the mounting location 24 results in resistive heating of the resistive heating track 42. Some of the heat generated by the resistive heating track 42 is conducted into the underlying metallic substrate 41 of the heater element 40.
[0101] In use, heat generated by the heater element 40 is conveyed to the plug of aerosol-forming substrate 34. The heating of the aerosol-forming substrate 34 results in vapours being evolved from the aerosol-forming substrate. In response to a user drawing on the mouth end 32 of the article 30, a flow of ambient air (as indicated by arrows in FIG. 1) is sucked into an air passageway 28 circumferentially arranged between the elongate housing 21 and the blind cavity 26. The flow of air then enters the distal end 31 of the aerosol-generating article 30 and passes through the plug of aerosol-forming substrate 34 to mix with the vapours evolved from the aerosol-forming substrate. The vapour mixture then passes downstream through the interior of the aerosol-generating article 30 towards the mouth end 32, during which time the vapour condenses to form aerosol. The aerosol passes through the mouthpiece filter 37, from where it is inhaled into the lungs of the user.
[0102] FIGS. 2a and 2b show perspective views from of the upper and lower surfaces respectively of the heater element 40 used in the aerosol-delivery system 10 of FIG. 1. The terms upper and lower are used in a relative sense only. As stated above, the heater element 40 is formed of a metallic substrate 41. The metallic substrate 41 is titanium or stainless steel. However, in alternative examples, the metallic substrate 41 may be formed of other metals or alloys. The resistive heating track 42 is overlaid on a surface of the metallic substrate 41 (see FIG. 2b). For the example shown in FIGS. 2a and 2b, the resistive heating track 42 is in the form of fine metal wire deformed into a coil shape. However, in alternative examples (not shown), the resistive heating track 41 may take other forms, such as being a metal sheet which has been stamped or otherwise formed into a coil-shaped pattern. The metallic substrate 41 of the heater element 40 extends longitudinally along axis 43 between proximal end 44 and distal end 45, plus laterally outwards from the axis to define a blade-shaped profile for the heater element 40. The heater element 40 is detachably mounted to the mounting location 24 at proximal end 44. First and second planar surfaces 46, 47 define respective lower and upper surfaces of the metallic substrate 41. The resistive heating track 42 is arranged on the lower surface 46 (see FIG. 2b). A plurality of surface notches 48 are formed on the upper surface 47. The surface notches 48 extend partially through the thickness, t, of the metallic substrate 41. The plurality of surface notches 48 are arranged in three groups 49a,b,c. Group 49a of surface notches 48 are provided in an inner region 50 of the heater element 40, the inner region extending between the proximal end 44 and approximately 33% of the length, L, of the heater element relative to the proximal end. For the example shown in FIG. 2a, approximately 40% of all of the surface notches 48 formed on the heater element 40 are located in this inner region 50 in group 49a. Groups 49b and 49c contain the remaining 60% of the surface notches 47 formed on the heater element 40, with both groups being laterally symmetric about axis 43 in a middle region 51 of the heater element. The middle region 51 extends between 33% and 90% of the length, L, of the heater element 40 relative to the proximal end 44. These two laterally symmetric groups 49b and 49c of surface notches 48 join at axis 43 to define an arrowhead shape when viewed in plan, i.e. in the direction of arrow A. The surface notches 48 of group 49a extend across in excess of 95% of the lateral width, W, of the heater element 40. For the heater element 40 of FIGS. 2a and 2b, no surface notches 48 are defined on the lower surface 46 of the metallic substrate 41. However, in alternative examples (such as the exemplary heater element of FIGS. 6a-c, discussed in subsequent paragraphs), a plurality of surface notches 48 is also provided on the lower surface 46 of the metallic substrate 41.
[0103] For the heater element of FIGS. 2a and 2b, the surface notches 48 defined on the heater element 40 occupy a cumulative volume of ?18% of a corresponding heater element free of any such notches. This provides ?18% mass reduction relative to such a corresponding heater element free of any such notches. In alternative examples, the surface notches 48 occupy a larger or smaller cumulative volume according to the degree of heat flow management desired. Further, in alternative examples (not shown), the distribution of surface notches 48 along the length, L, and across the width, W, of the heater element 40, and the proportion of surface notches 48 in the inner and middle regions 50, 51 may differ from that shown and discussed for the heater element of FIGS. 2a and 2b.
[0104] FIGS. 3 to 9 show views of portions of various exemplary heater elements 40 having differing arrangements of surface notches or sub-surface cavities to the heater element illustrated in FIGS. 2a,b. For convenience, features common to the various exemplary heater elements 40 are referred to using like reference signs.
[0105] FIG. 3a is a plan view (in the direction of arrow A of FIG. 2a) of the upper surface 47 of a portion of an exemplary heater element 40. A plurality of surface notches 48 are formed on the upper surface 47 of the metallic substrate 41. The surface notches 48 are circular in plan, being of radius, r. The surface notches 48 are formed in a repeating honeycomb-type pattern, in which adjacent rows of the notches are offset from each other. As shown in the sectional view of FIG. 3b, each of the surface notches 48 extends into the upper surface 47 of the metallic substrate 41 to provide a notch surface profile which is part-spherical. Each notch 48 extends part way through the thickness, t, of the substrate 41 for a depth, d (see FIG. 3b). As the notch surface profile is part-spherical, the depth d equates to radius r. In alternative examples (not shown), the surface profile of the notches 48 is ellipsoidal. In further alternative examples (not shown), the dimensions of the notches 48 are varied in different regions of the heater element 40. Further, the spacing between adjacent notches 48 may be varied in different regions of the heater element 40. By way of example, with reference to FIG. 2a, the notches 48 in inner region 50 may be larger or spaced closer together than those in middle region 51. Such variation in notch dimensions and spacing between adjacent notches 48 in different regions of the heater element 40 can be used to provide different levels of thermal conductivity in those different regions.
[0106] FIG. 4a is a plan view (in the direction of arrow A of FIG. 2a) of the upper surface of a portion of another exemplary heater element 40. A plurality of surface notches 48 are formed on the upper surface 47 of the metallic substrate 41. In common with the example of FIGS. 3a,b, the surface notches 48 are circular in plan, being of radius, r, and formed in a repeating honeycomb-type pattern, in which adjacent rows of the notches are offset from each other. However, as shown in the sectional view of FIG. 4b, each of the surface notches 48 has a cylindrical bore which extends into the upper surface 47 of the metallic substrate 41 to provide a notch surface profile which is cylindrical. Each notch 48 extends part way through the thickness, t, of the substrate 41 for a depth, d (see FIG. 4b). In alternative examples (not shown), the dimensions of the notches 48 are varied in different regions of the heater element 40. Further, the spacing between adjacent notches 48 may be varied in different regions of the heater element 40. By way of example, with reference to FIG. 2a, the notches 48 in inner region 50 may be larger or spaced closer together than those in middle region 51. Such variation in notch dimensions and spacing between adjacent notches 48 in different regions of the heater element 40 can be used to provide different levels of thermal conductivity in those different regions.
[0107] FIG. 5a is a plan view (in the direction of arrow A of FIG. 2a) of the upper surface 47 of a portion of an exemplary heater element 40. A plurality of surface notches 48 are formed on the upper surface 47 of the metallic substrate 41. The surface notches 48 are hexagonal in plan. The surface notches 48 are formed in a repeating honeycomb-type pattern, in which adjacent rows of the notches are offset from each other. As shown in the sectional view of FIG. 5b, each of the surface notches 48 has a hexagonal bore which extends into the upper surface 47 of the metallic substrate 41. Each notch 48 extends part way through the thickness, t, of the substrate 41 for a depth, d (see FIG. 5b). In alternative examples (not shown), the dimensions of the notches 48 are varied in different regions of the heater element 40. Further, the spacing between adjacent notches 48 may be varied in different regions of the heater element 40. By way of example, with reference to FIG. 2a, the notches 48 in inner region 50 may be larger or spaced closer together than those in middle region 51. Such variation in notch dimensions and spacing between adjacent notches 48 in different regions of the heater element 40 can be used to provide different levels of thermal conductivity in those different regions.
[0108] FIG. 6a is a plan view (in the direction of arrow A of FIG. 2a) of the upper surface 47 of a portion of an exemplary heater element 40. The notch arrangement on the upper surface 47 is identical to that of the heater element 40 of FIG. 5a, with a plurality of surface notches 48 formed on the upper surface of the metallic substrate 41. The surface notches 48 are hexagonal in plan and formed in a repeating honeycomb-type pattern, in which adjacent rows of the notches are offset from each other. However, the heater element of this example differs from that of FIGS. 5a,b in that an arrangement of surface notches 48 are also provided on the lower surface 46 of the metallic substrate 41. As for the notches on the upper surface 47, the notches on the lower surface 46 are hexagonal in plan. However, the notches 48 on the lower surface 46 are fewer in number than those on the upper surface 47. As can be seen in FIG. 6b, the notches 48 on the lower surface 46 are positioned on either side of the resistive heating track 42. As shown in the sectional view of FIG. 6c, each notch 48 extends part way through the thickness, t, of the substrate 41 for a depth, d. In alternative examples (not shown), the dimensions of the notches 48 are varied in different regions of the heater element 40. Further, the spacing between adjacent notches 48 may be varied in different regions of the heater element 40. By way of example, with reference to FIG. 2a, the notches 48 in inner region 50 may be larger or spaced closer together than those in middle region 51. Such variation in notch dimensions and spacing between adjacent notches 48 in different regions of the heater element 40 can be used to provide different levels of thermal conductivity in those different regions.
[0109] FIG. 7a is a plan view (in the direction of arrow A of FIG. 2a) of the upper surface 47 of a portion of an exemplary heater element 40. In contrast to the exemplary heater elements 40 of FIGS. 3 to 6, no surface notches 48 are provided on the metallic substrate. Rather, a layer of spherical sub-surface cavities 480 is embedded within the metallic substrate 41, each cavity having diameter, ?(see the sectional view of FIG. 7b). The outline of these sub-surface cavities 480 is shown with a dashed line in the plan view of FIG. 7a. The sub-surface cavities 480 are formed in a repeating honeycomb-type pattern, in which adjacent rows of the embedded cavities 480 are offset from each other (see FIG. 7a). In alternative examples (not shown), the sub-surface cavities 480 are ellipsoidal in form. In further alternative examples (not shown), the dimensions of the sub-surface cavities 480 are varied in different regions of the heater element 40. Further, the spacing between adjacent cavities 480 may be varied in different regions of the heater element 40. By way of example, with reference to FIG. 2a, sub-surface cavities 480 in inner region 50 may be larger or spaced closer together than those in middle region 51. Such variation in cavity dimensions and spacing between adjacent sub-surface cavities 480 in different regions of the heater element 40 can be used to provide different levels of thermal conductivity in those different regions.
[0110] FIG. 8 is a sectional view of a heater element 40 similar to that shown in FIG. 7b, but differing in that three layers of sub-surface cavities 480 are embedded within the metallic substrate 41. In alternative examples (not shown), where multiple layers of sub-surface cavities 480 are embedded within the metallic substrate 41, the layers may differ from each other in terms of the size or spacing of the cavities 480 in each layer.
[0111] FIG. 9 is a sectional view of a heater element 40 corresponding to a combination of the examples of FIGS. 5a,b and 7a,b. As can be seen, an arrangement of surface notches 48 are formed on the upper surface 47 of the metallic substrate 41, the notches being hexagonal in plan (as per FIG. 5a). However, in addition, a layer of sub-surface cavities 480 is embedded in the metallic substrate 41 (as per FIG. 7a).
[0112] FIG. 10 shows a perspective view of five different heater elements 40, each having different arrangements of surface notches 48.
[0113] FIG. 11 is a schematic view of a machining assembly 60 for manufacturing a heater element from a sheet 400 of the metallic substrate 41 material. The machining assembly 60 has a tool holder 61 holding a machining tool 62. The sheet 400 of metallic substrate is provided and secured in position relative to the machining assembly 60. The sheet 400 has a thickness corresponding to the desired thickness, t, of the heater elements 40 described in the previous paragraphs, but has a width and a length sufficient for multiple heater elements 40 to be formed from a single sheet 400. The machining assembly 60 operates the machining tool 62 to machine an individual surface notch 48 in the upper surface of the metal sheet 400 and then traverses (see arrows in FIG. 11) the tool holder 61 and machining tool 62 over the surface of the metal sheet 400 to repeat the machining operation at multiple desired locations. Once the machining operation is completed, resistive heater tracks 62 are arranged at predetermined intervals on the lower surface of the sheet 400. Individual heater elements 40 are then cut from the sheet 400, with dashed lines in FIG. 11 showing the outline of two such heater elements 40. In another example (not shown), the surface notches 48 are chemically etched in the surface of the metal sheet 400, rather than being mechanically formed.
[0114] For the purpose of the present description and of the appended claims, except where otherwise indicated, all numbers expressing amounts, quantities, percentages, and so forth, are to be understood as being modified in all instances by the term about. Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein. In this context, therefore, a number A is understood as A?10% of A. Within this context, a number A may be considered to include numerical values that are within general standard error for the measurement of the property that the number A modifies. The number A, in some instances as used in the appended claims, may deviate by the percentages enumerated above provided that the amount by which A deviates does not materially affect the basic and novel characteristic(s) of the claimed invention. Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein.
