US20150181935A1 - Apparatus for Heating Smokeable Material - Google Patents

Abstract

An apparatus is configured to heat smokeable material to volatilize at least one component of the smokeable material. The apparatus comprises a heater with a temperature-sensitive element configured to alter its shape when heated in order to cause progressive heating of the smokeable material.

Description

TECHNICAL FIELD
• The present invention relates to apparatus for heating smokeable material.
BACKGROUND
• Smoking articles such as cigarettes, cigars and the like burn tobacco during use to create tobacco smoke. Attempts have been made to provide alternatives to these articles that burn tobacco by creating products that release compounds without burning. Examples of such products are so-called heat-not-burn products which release compounds by heating, but not burning, the material. The material may be for example tobacco or other non-tobacco products, which may or may not contain nicotine.
SUMMARY
• According to the present invention, there is provided an apparatus configured to heat smokeable material to volatilize at least one component of the smokeable material, wherein the apparatus comprises a heater with a temperature-sensitive element configured to alter its shape when heated in order to cause progressive heating of the smokeable material.
• The heater may be configured to trigger alteration of the shape of the temperature-sensitive element.
• The heater may be configured to trigger alteration of the shape of the temperature-sensitive element in response to a user action.
• The apparatus may be configured to trigger alteration of the shape of the temperature-sensitive element by causing an electrical current to pass through the element.
• The apparatus may be configured to resistively heat the temperature-sensitive element to cause alteration of the shape of the temperature-sensitive element.
• The heater may be configured to provide an area of elevated temperature, which area is small in comparison to the total surface area of the heater. For example, the region of elevated temperature may be less than 10%, or less than 20%, or less than 40% of the total surface area of the heater.
• The heater may be configured to cause the area of elevated temperature to migrate progressively along the heater as the temperature-sensitive element alters in shape.
• The progressive migration of the area of elevated temperature may cause corresponding progressive heating of the smokeable material.
• The temperature-sensitive element may extend from a first end of the heater to a second end, and the heater may be configured to progressively alter the shape of the temperature-sensitive element from the first end of the heater to the second end.
• The heater may comprise an electrode comprising the temperature-sensitive element.
• The heater may be configured to form an electrically resistive contact between the electrode comprising the temperature-sensitive element and a second electrode.
• The electrically resistive contact may change position relative to the smokeable material upon alteration of the shape of the temperature-sensitive element.
• The electrically resistive contact may be configured to provide an area of elevated temperature in a position substantially corresponding to the position of electrically resistive contact
• The electrically resistive contact may be configured to supply heat to the smokeable material and also to cause alteration of the shape of the temperature-sensitive element.
• The heater may be configured to cause the position of the electrically resistive contact to migrate progressively from the first end of the heater to a second end.
• The heater may comprise a plurality of electrical elements, wherein one or more of the electrical elements comprises the temperature-sensitive element.
• The heater may be configured to alter the position and/or shape of one or more of the electrical elements upon alteration of the shape of the temperature-sensitive element.
• The electrical elements may extend from a first end of the heater to a second end of the heater.
• The heater may be configured to form an initial electrically resistive contact at a first end of the heater.
• The apparatus may comprise a plurality of temperature-sensitive elements.
• The temperature-sensitive elements may form electrically resistive contact points at a plurality of different distances from a first end of the heater.
• The temperature-sensitive element may comprise a bimetallic strip.
• The temperature-sensitive element may comprise a shape memory material.
• The shape memory material may comprise a shape memory alloy.
• The heater may be configured to trigger alteration of the shape of the temperature-sensitive element by heating the shape memory material to a transition temperature of the shape memory material.
• The apparatus may be configured to heat the smokeable material without combusting the smokeable material.
BRIEF DESCRIPTION OF THE FIGURES
• Embodiments will now be described, by way of example only, with reference to the accompanying Figures, in which:
• FIG. 1 is a perspective, partially cut-away illustration of an example of an apparatus configured to heat smokeable material, according to a first embodiment;
• FIG. 2 is an exploded, partially cut-away view of the apparatus ofFIG. 1;
• FIG. 3A is a diagram illustrating the heater assembly shown inFIG. 1 prior to use;
• FIG. 3B is a diagram illustrating the heater assembly shown inFIG. 1 in use at a first time point;
• FIG. 3C is a diagram illustrating the heater assembly shown inFIG. 1 in use at a second time point which is later than the first time point;
• FIG. 4A is a diagram illustrating an example of the heater assembly of a second embodiment prior to use;
• FIG. 4B is a diagram illustrating the heater assembly of a second embodiment in use at a first time point;
• FIG. 4C is a diagram illustrating the heater assembly of a second embodiment in use at a second time point which is later than the first time point;
• FIG. 5 is a transverse cross-sectional view of an example of the heater of a third embodiment;
• FIG. 6 is a perspective semi-transparent view and a transverse cross-sectional view of an example of the heater assembly of a fourth embodiment in use; and
• FIG. 7 is a perspective semi-transparent view and a transverse cross-sectional view of an example of the heater assembly of a fifth embodiment in use.
DETAILED DESCRIPTION
• As used herein, the term “smokable material” includes materials that provide volatilized components upon heating, typically in the form of an aerosol. “Smokable material” includes any tobacco-containing material and may, for example, include one or more of tobacco, tobacco derivatives, expanded tobacco, reconstituted tobacco or tobacco substitutes. “Smokable material” also may include other, non-tobacco, products, which, depending on the product, may or may not contain nicotine.
• FIG. 1 shows an example of an apparatus for heating smokeable material according to a first embodiment.
• As shown inFIG. 1, theapparatus1 comprises anenergy source2, aheater3, and aheating chamber4, which containssmokeable material5.
• Theenergy source2 of this example comprises a Li-ion battery. Any suitable type of energy source, such as a Ni battery, alkaline battery and/or the like, may alternatively be used. Theenergy source2 may be rechargeable. Theenergy source2 is electrically coupled to theheater3 to supply electrical energy to theheater3 when required.
• Theheating chamber4 is configured to receivesmokeable material5 so that thesmokeable material5 can be heated in theheating chamber4. Theheater3 andheating chamber4 are arranged so that theheater3 is able to heat theheating chamber4. Generally, and in the embodiment shown inFIG. 1, theheating chamber4 is located adjacent to theheater3 so that thermal energy from theheater3 heats thesmokeable material5 in theheating chamber4. Theheater3 heats theheating chamber4 sufficiently to volatilize aromatic compounds and nicotine if present in thesmokeable material5 without burning thesmokeable material5.
• In the embodiment shown inFIG. 1, theheater3 is in the form of a substantially cylindrical, elongate rod, which extends along part of a central longitudinal axis of theapparatus1, towards the mouth end. Theheating chamber4 is located around the circumferential, longitudinal surface of theheater3. Thesmokeable material5 is in the form of a hollow, annular cylinder which fits within theheating chamber4. Thesmokeable material5 is located within theapparatus1 such that theheater3 is positioned within the central longitudinal cavity of thesmokeable material5. Thesmokeable material5 thus fits closely around theheater3 to ensure efficient heat transfer from theheater3 to thesmokeable material5. Theheating chamber4 andsmokeable material5 therefore comprise co-axial layers around theheater3. However, as will be evident from the discussion below, in other embodiments, other shapes and configurations of theheater3,heating chamber4, andsmokeable material5 can alternatively be used.
• In the embodiment shown inFIG. 1, thesmokeable material5 comprises a tobacco blend, or some other volatisable material.
• FIG. 2 is an exploded diagram of the apparatus shown inFIG. 1. As shown inFIG. 2, theapparatus1 further comprises anannular mouthpiece6 and ahousing7 in which the components of theapparatus1 such as theenergy source2 andheater3 are contained.
• In the embodiment shown, thehousing7 comprises an approximately cylindrical tube with theenergy source2 located towards its first end8, and theheater3 andheating chamber4 located towards its opposite,second end9. As shown inFIG. 1, theenergy source2 andheater3 are aligned along a central longitudinal axis of thehousing7.
• Themouthpiece6 attaches to thesecond end9 of thehousing7, which may also be considered to be the mouth end of theapparatus1. Themouthpiece6 is located adjacent to theheating chamber4 andsmokeable material5, such that theannular mouthpiece6 provides apassageway10 for fluid communication between the mouth of the user and theheating chamber4.
• Thermal insulation11 is provided between theheater3 and thehousing7 to reduce heat loss from theapparatus1 and therefore improve the efficiency with which thesmokeable material5 is heated. In the embodiment shown inFIGS. 1 and 2, a layer ofthermal insulation11, comprising a substantially tubular length ofinsulation11, is located co-axially around theheater3.
• As shown inFIG. 2, the layer ofthermal insulation11 in this example comprises vacuum insulation, and in particular in this example comprises a double-wall arrangement12 enclosing aninternal region13. An example of a suitable material for thedouble wall arrangement12 is stainless steel and an example of a suitable thickness for the walls of thedouble wall arrangement12 is approximately 100 μm. The internal region orcore13 of theinsulation11 comprises a void. In other embodiments, theinternal region13 may include open-cell porous materials comprising, for example, polymers, aerogels or other suitable materials, which may be evacuated to a low pressure. The pressure in theinternal region13 is generally in the range of 0.1 to 0.001 mbar. The thermal conductivity of thethermal insulation11 is generally in the range of 0.004 to 0.005 W/mK.
• A reflective coating may be applied to the internal surfaces of thedouble wall arrangement12 to further reduce heat losses through thethermal insulation11.
• The coating may, for example, comprise an aluminium infrared (IR) reflective coating.
• Theapparatus1 comprisesair conduits14, which allow external air to be drawn into thehousing7 and through theheating chamber4 when theapparatus1 is in use. Theair conduits14 compriseapertures14 in thehousing7 which are located upstream from thesmokeable material5 andheating chamber4 towards the first end8 of thehousing7. Theair conduits14 may also allow any excess heat from theenergy source2 to be dissipated.
• Theheating chamber4 may comprise one ormore inlet valves15 which, when closed, prevent gaseous flow from theair conduits14 into theheating chamber4. Thevalves15 thereby reduce the diffusion of air and smokeable material flavours from theheating chamber4, as discussed in more detail below. Thevalves15 may be located within acylindrical buffer16 which is positioned at the end of theheating chamber4 towards the first end8 of thehousing7. More specifically, thecylindrical buffer16 may be positioned to separate theenergy source2 andair conduits14 on one side, from theheater3,heating chamber4, andsmokeable material5 on the other side of thecylindrical buffer16. Thebuffer16 thereby provides heat insulation between theenergy source2 and theheater3 to prevent direct transfer of heat from one to the other. Thebuffer16 also comprises an arrangement (not shown) for electrically coupling theheater3 to thepower source2.
• An example of theheater3 is shown in detail inFIG. 3A. Theheater3 comprises a temperature-sensitive element17 in the form of abimetallic strip18.
• The shape of a bimetallic strip is temperature-sensitive. Bimetallic strips comprise two layers of metal having different coefficients of expansion, which thereby possess different capacities to expand as they are heated. The layers are attached to one another. When heated, the bimetallic strip bends or buckles due to the different expansion properties of the two layers. In this way, a change in temperature is converted into physical displacement.
• As used herein, “bending”, “buckling”, “curvature” and similar terms refer to the alteration of the shape of thebimetallic strip18 which occurs as the strip is heated or cooled. The degree of curvature of thebimetallic strip18 may be related to the temperature such that at a higher temperature, the strip demonstrates a greater degree of curvature. The degree of curvature of thebimetallic strip18 may be proportional to the magnitude of the alteration in temperature.
• Thebimetallic strip18 may function as an electrical conductor within the temperature-sensitive element17. In addition, or alternatively, the temperature-sensitive element17 may comprise a separate electrical conductor, wherein, in combination, thebimetallic strip18 and electrical conductor are arranged such that the shape and/or position of the electrical conductor may be altered by the bending of thebimetallic strip18.
• Suitable bimetallic strips for use in the apparatus may vary in terms of, for example, thickness and cross-sectional shape of the metal layers, the metal composition, the arrangement by which the metals are bonded together, etc., and these variables may affect the properties of the bimetallic strip, such as the capacity of the strip to bend, the thermal conductivity, the electrical conductivity, etc. In the embodiment shown, thebimetallic strip18 comprises steel and copper. However any other combination of metals may be used, such as for example, manganese and copper or brass and steel. In embodiments in which thebimetallic strip18 functions as an electrical conductor within the temperature-sensitive element17, bimetallic strips comprising a metal that is a particularly good conductor of electricity, such as copper, may be used.
• Theheater3 also comprises a centralcylindrical element19. Thecylindrical element19 has an annular configuration and in essence is in the form of an elongated tube, a central longitudinal cavity of which forms theheating chamber4.
• In the embodiment shown, a cavity is provided between the outer surface of theheater3 and thecylindrical element19. The temperature-sensitive element17 is positioned within the cavity and is arranged to contact the outer surface of thecylindrical element19. Alteration of the shape of the temperature-sensitive element17 alters the position of contact between the temperature-sensitive element17 and thecylindrical element19. Contact between the temperature-sensitive element17 and thecylindrical element19 may be electrically resistive such that, in use, thecylindrical element19 is heated in the position at which it contacts the temperature-sensitive element17.
• In general, thecylindrical element19 may be composed of any material that is both electrically and thermally conductive. Electrical conductivity allows thecylindrical element19 to form part of an electrical circuit, for example with the temperature-sensitive element17. Thermal conductivity allows heat generated by resistive contact with the temperature-sensitive element17 on an outer surface of thecylindrical element19 to be transmitted into theheating chamber4 within thecylindrical element19. It may also be desirable for heat to be conducted circumferentially around thecylindrical element19.
• In the embodiment shown, thecylindrical element19 is made of aluminium or copper. However, thecylindrical element19 may be made of a combination of materials, for example a combination of an electrically conductive material and a thermally conductive material. Suitable materials may include certain plastics, metals, glass, and ceramics.
• While thecylindrical element19 may be thermally conductive in a circumferential direction to allow efficient heat transfer from aresistive contact point21 around theheating chamber4, it may be desirable that thermal conduction along the length of thecylindrical element19 is minimised to ensure that only a short longitudinal section of theheating chamber4 is at an elevated temperature at any given time. The small section of elevated temperature, which may be referred to as the “heating zone”, may comprise, for example, a circumferential band around thecylindrical element19. To minimise the effect of thermal conduction longitudinally along thecylindrical element19, thecylindrical element19 may have a greater capacity to conduct thermal energy circumferentially around theheating chamber4 than longitudinally along theheating chamber4. Thecylindrical element19 may inherently possess this directional thermal conductivity, or may comprise a lining having suitable properties of thermal conductivity. For example, thecylindrical element19 may comprise a plurality of individual panels of aluminium arranged longitudinally along the inner surface of thecylindrical element19. The panels may be bonded together and/or bonded to thecylindrical element19 using a thermally insulating bonding agent. Other arrangements may be used. For example, instead of comprising individual panels, thecylindrical element19 may comprise an electrically and thermally conductive material that is coiled around theheating chamber4.
• The temperature-sensitive element17 may extend substantially along the entire length of thecylindrical element19.
• Prior to use of theapparatus1, the temperature-sensitive element17 is only in contact with thecylindrical element19 at a position close to afirst end20 of the cylindrical element, as shown inFIG. 3A.
• In use, contact between the temperature-sensitive andcylindrical elements17,19 is electrically resistive. As used herein, an electrically resistive contact is a point of contact between theelements17,19. Electrical resistance at the contact point generates heat in the region of contact, which is dissipated into the temperaturesensitive element17 and thecylindrical element19.
• Thebimetallic strip18 of the temperature-sensitive element17 is configured to bend when heated such that, when the apparatus is in use, resistive contact between the temperature-sensitive andcylindrical elements17,19 causes the bimetallic strip to alter in shape. This alteration in shape causes the location of the resistive contact with thecylindrical element19 to change. In particular, as illustrated inFIGS. 3A to 3C, the location of resistive contact may be caused to progress longitudinally along thecylindrical element19. In this way, heat may be transmitted into thecylindrical element19 at any particular longitudinal position along its length. This is described in more detail below.
• The temperature-sensitive andcylindrical elements17,19 are electrically coupled to theenergy source2, which causes electrical current to flow through theelements17,19 and create the resistive heating effect referred to above. The electrical coupling between one or both of theelements17,19 and theenergy source2 is controlled by means of a switch (not shown), which may be user-operable. For example, the switch may comprise a push-button or similar at the exterior of theapparatus1 or may be puff-activated.
• In use, as the temperature-sensitive element17 is resistively heated, thebimetallic strip18 bends, and the position at which the temperature-sensitive element17 contacts thecylindrical element19 is altered. The new position of resistive contact heats a new section of the temperature-sensitive element17, which causes further bending of thebimetallic strip18 and further alteration of the position at which the temperature-sensitive element17 contacts thecylindrical element19. In this way, the position of resistive contact between the temperature-sensitive andcylindrical elements17,19 may move progressively along thecylindrical element19, driven by resistive contact between theelements17,19 and the curvature of thebimetallic strip18. This process is illustrated inFIGS. 3B and 3C.
• Theheater3 in use at a first time point is shown inFIG. 3B, and in use at a second time point is shown inFIG. 3C, wherein the second time point is later than the first time point. As shown inFIG. 3B, the temperature-sensitive andcylindrical elements17,19 are in resistive contact, and the electrical current passing between theelements17,19 generates heat in the region of the point ofcontact21. The region of thecylindrical element19 that is resistively heated forms theheating zone22. The heat generated by theresistive contact21 is conducted into the temperature-sensitive element17 and causes thebimetallic strip18 to begin to bend and alter its shape in the adjacent region. As shown inFIG. 3C, curvature of thebimetallic strip18 alters the relative positions of theelements17,19, forming a new region ofresistive contact21′ between theelements17,19, and anew heating zone23. The bending of thebimetallic strip18 thereby continues, gradually altering the shape of the temperature-sensitive element17 from one end of theheater3 to the other, and thus gradually forming new points of resistive contact between theelements17,19 from one end of theheater3 to the other. The position of heat-generating resistive contact between theelements17,19 and the heating zone thus migrates, preferably at a substantially constant rate, along the length of theheater3.
• By this arrangement, theheater3 provides heat in a narrow circumferential band, referred to as theheating zones22,23, around theheater3, in a position substantially corresponding to the position ofresistive contact21,21′, between theelements17,19. Because heating occurs only at the point ofresistive contact21,21′ between theelements17,19, the heating zone provided by theheater3 is relatively narrow. That is, only a relatively small portion of the longitudinal length of theheater3 is at a substantially elevated temperature at any given time. The area of elevated temperature may be small in comparison to the total surface area of thecylindrical element19, and may be, for example, 10%, 20% or 40% of the total surface area of thecylindrical element19.
• The width of theheating zones22,23 (that is, the longitudinal extension of the heating zone along the heater3) may in general be influenced by a number of factors. For example, the capacity of the temperature-sensitive element17 to conduct heat, the capacity of thebimetallic strip18 to bend, the rate of migration of the heating zone, the current provided by theenergy source2, and the nature of the resistive contact between theelements17,19, may all be contributing factors. In general, the heating zone may be between approximately 1 mm and 2 cm wide.
• The rate at which each heating zone migrates may also be influenced by a number of factors. For example, different bimetallic strips may bend by different amounts, at different rates and at different temperatures. The current provided by theenergy source2 may also be important, wherein the greater the current, the greater the rate of migration. The heating zone may migrate at a rate of between approximately 5 mm and 30 mm every 60 seconds.
• The process continues until thebimetallic strip18 has been bent as fully as possible, until the heating zone has migrated along the entire length of theheater3, or until the supply of electrical current is terminated. Theapparatus1 may comprise an arrangement by which the supply of electrical current is terminated once thebimetallic strip18 has been bent as fully as possible.
• In use, theapparatus1 provides volatilized smokeable material compounds for inhalation by the user via themouthpiece6.
• To use theapparatus1, the user activates theheater3 as described above using the switch. As shown inFIG. 1 and discussed above, theheating chamber4 andsmokeable material5 may be located in a central region of thehousing7, and theheater3 may be located around the longitudinal surface of theheating chamber4. In this arrangement, in use, thermal energy emitted by the resistive contact in theheater3 travels in a radial direction inwards from the longitudinal internal surface of thecylindrical element19 into theheating chamber4 and thesmokeable material5.
• Theheater3 is arranged so that the heating zone produced by theheater3 migrates towards the second,mouth end9 of theapparatus1.
• Because theheater3 provides a narrow circumferential heating zone, it supplies thermal energy to thesmokeable material5 located radially adjacent to that region of theheater3 without substantially heating the remainder of thesmokeable material5. The heated section ofsmokeable material5 may comprise a section or ring ofsmokeable material5 which lies directly circumferentially adjacent to the heating zone produced by theheater3. In this way, a small distinct section of thesmokeable material5 can be heated individually. The section ofsmokeable material5 that is heated has a mass and volume which is significantly less than the body ofsmokeable material5 as a whole. Furthermore, since the heating zone produced by theheater3 migrates progressively along the longitudinal length of theheater3, the specific section ofsmokeable material5 being heated also migrates progressively along the length of thesmokeable material5, and the precise section ofsmokeable material5 that is being heated is continually changing.
• If thesmokeable material5 comprises tobacco for example, a suitable temperature for volatilizing the nicotine and other aromatic compounds may be above 120° C., such between 150° C. and 250° C. or between 130° C. and 180° C. Therefore, examples of temperatures in the heating zone include 150° C., 180° C. and 250° C.
• The region of theheater3 that is immediately in-front of the heating zone, into which the heating zone is progressing, may be pre-heated by longitudinal thermal conduction from the heating zone. This region may comprise a pre-volatilizing region of theheater3, which heats up thesmokeable material5 in preparation for its components to be volatilized by the approaching heating zone. This pre-heating does not heat thesmokeable material5 to a sufficient temperature to volatilize nicotine or other volatilizable material. A suitable temperature could be less than 120° C., such as approximately 100° C.
• Once theheater3 has been activated, thesmokeable material5 is heated and the user may obtain volatilized smokeable material compounds by drawing on themouthpiece6 of theapparatus1. As the user draws on themouthpiece6, air is drawn into theheating chamber4 of theapparatus1 via theair conduits14 and the one ormore valves15. As it is drawn through the heatedsmokeable material5 in theheating chamber4, the air is enriched with smokeable material vapours, such as aroma vapours, before being inhaled by the user at themouthpiece6.
• Between draws, thevalves15 may be closed so that all volatilized substances remain contained inside thechamber4 pending the next draw. The partial pressure of the volatilized substances between puffs approaches the saturated vapour pressure and the amount of evaporated substances therefore depends largely on the temperature in theheating chamber4. This helps to ensure that the delivery of volatilized nicotine and aromatic compounds remains constant throughout the use of the smoking article. Thevalves15 open as the user draws on themouthpiece6 so that gaseous flow may be drawn through theheating chamber4 to carry volatilized smokeable material components to the user via themouthpiece6. In some embodiments, a membrane may be located in thevalves15 to ensure that no oxygen enters thechamber4. Thevalves15 may be breath-actuated so that they open when the user draws on themouthpiece6. Thevalves15 may close when the user stops drawing. Alternatively, thevalves15 may, for example, close following the elapse of a predetermined period after their opening. Optionally, a mechanical or other suitable opening/closing arrangement may be present so that thevalve15 opens and closes automatically.
• FIG. 4 shows an embodiment in which the temperature-sensitive elements17 comprise a shape memory material. Theheater3 shown inFIG. 4 operates in substantially the same manner as theheater3 described above with reference toFIGS. 1-3, and is suitable for use in anapparatus1 as described above with reference toFIGS. 1-3. The difference between the embodiment ofFIG. 4 and the embodiment shown inFIGS. 1-3 is that the temperature-sensitive elements17 of theheater3 comprise ashape memory material28 instead of abimetallic strip18.
• Theshape memory material28 may be a shape memory alloy. Shape memory alloys (also known as SMAs, smart metals, memory metals, memory alloys, muscle wires, smart alloys) are temperature-sensitive materials that alter their shape to a pre-determined alternative shape when heated. A number of different shape memory alloys are known and any suitable shape memory alloy may be used. In this way, a change in temperature is converted into physical displacement.
• As used herein, “transformation” and similar terms refer to the alteration of the shape of theshape memory material28 which occurs as the strip is heated. Theshape memory material28 alters its shape at a temperature herein referred to as the “transition temperature”. The transition temperature may be a similar temperature, or may be less than, the volatilization temperature of thesmokeable material5. Generally, the transition temperature of suitable shape memory materials may be above 50° C., such between 80° C. and 150° C. or between 90° C. and 130° C. Therefore, examples of shrink temperatures of suitable heat-shrink materials include 100° C. and 120° C.
• Theshape memory material28 may function as an electrical conductor within the temperature-sensitive element17. For example, theshape memory material28 may comprise an electrically conductive shape memory alloy. In addition, or alternatively, the temperature-sensitive element17 may comprise a separate electrical conductor, wherein, in combination, theshape memory material28 and electrical conductor are arranged such that the shape and/or position of the electrical conductor may be changed by the transformation of theshape memory alloy28. For example, a non-electrically conductive shape memory polymer may be used together with an electrode.
• Suitable shape memory materials for use in the apparatus may vary in terms of, for example, transition temperature, capacity to change shape, thermal conductivity, electrical conductivity, composition, thickness, cross-sectional shape, etc. In the embodiment shown, theshape memory material28 is a shape memory alloy and comprises an alloy of copper-zinc-aluminium-nickel, however any other suitable shape memory material may be used, which may be a shape memory alloy comprising, for example, Ag—Cd, Au—Cd, Co—Ni—Al, Co—Ni—Ga, Cu—Al—Ni, Cu—Sn, Cu—Zn, Cu—Zn—X (X═Si, Al, Sn), Fe—Pt, Fe—Mn—Si, Mn—Cu, Ni—Fe—Ga, Ni—Ti, Ni—Ti—Nb, Ni—Mn—Ga, Ti—Pd, or Pt alloys. Theshape memory material28 may alternatively, or in addition, comprise a shape memory polymer.
• Theheater3 also comprises a centralcylindrical element19. Thecylindrical element19 may be the same as that shown inFIG. 3, in which case the same considerations regarding thecylindrical element19 apply as were discussed above in relation to the embodiment ofFIG. 3.
• In the embodiment shown, a cavity is provided between the outer surface of theheater3 and thecylindrical element19. The temperature-sensitive element17 is positioned within the cavity and is arranged to contact the outer surface of thecylindrical element19. Alteration of the shape of the temperature-sensitive element17 alters the position of contact between the temperature-sensitive element17 and thecylindrical element19.
• The temperature-sensitive elements17 extend substantially along the entire length of thecylindrical element19. Prior to use of theapparatus1, the temperature-sensitive elements17 are only in contact with thecylindrical element19 at a position close to afirst end20 of the cylindrical element, as shown inFIG. 4A.
• In use, points ofcontact21 between the temperature-sensitive andcylindrical elements17,19 are electrically resistive. When a current is passed between the temperature-sensitive andcylindrical elements17,19, the resistive contact heats theshape memory material28 to a temperature above the transition temperature, causing the temperature-sensitive elements17 to alter their shape in the region of the points ofresistive contact21. Transformation of theshape memory material28 causes the position at which the temperature-sensitive element17 contacts thecylindrical elements19 to be altered. The new position of resistive contact heats a new section of the temperature-sensitive element17, which causes alteration of the shape of a new section ofshape memory material28, and further alteration of the position at which the temperature-sensitive element17 contacts thecylindrical element19. In this way, the position of resistive contact between the temperature-sensitive andcylindrical elements17,19 may move progressively along thecylindrical element19, driven by resistive contact between the elements and the transformation of theshape memory material28. This process is illustrated inFIGS. 4B and 4C.
• Theheater3 in use at a first time point is shown inFIG. 4B, and in use at a second time point is shown inFIG. 4C, wherein the second time point is later than the first time point. As shown inFIG. 4B, the temperature-sensitive andcylindrical elements17,19 are in resistive contact, and the electrical current passing between theelements17,19 generates heat in the region of the point ofcontact21. This heated region is heatingzone22. The heat generated by theresistive contact21 heats the adjacent section ofshape memory material28 above the transition temperature and thereby causes theshape memory material28 to begin to alter its shape in the adjacent region. Transformation of theshape memory material28 alters the relative positions of theelements17,19, forming a new region ofresistive contact21′ between theelements17,19, and anew heating zone23. The transformation of the shape memory material thereby continues, gradually altering the shape of the temperature-sensitive element17 from one end of theheater3 to the other, and thus gradually forming new points of resistive contact between theelements17,19 from one end of theheater3 to the other. The position of heat-generatingresistive contact21 between theelements17,19 and the heating zone thus migrates at a substantially constant rate along the length of theheater3.
• In the embodiment shown inFIG. 4, theheater3 comprises two temperature-sensitive elements17, each comprising ashape memory material28. In some embodiments, theheater3 may comprise a plurality of temperature-sensitive elements17, each comprising abimetallic strip18 orshape memory alloy28. In some embodiments, theheater3 may comprise a plurality of temperature-sensitive elements17, one or more of which comprises abimetallic strip18 and one or more of which comprises ashape memory alloy28.
• Examples of such arrangements are shown inFIG. 4, in which theheater3 comprises two temperature-sensitive elements17, each comprising ashape memory material28, and inFIG. 5, in which theheater3 comprises six temperature-sensitive elements17, each comprising abimetallic strip18.
• The use of a plurality of temperature-sensitive elements17 may offer a number of advantages. With reference to the embodiment shown inFIG. 5, since there are six temperature-sensitive elements17, there are six points ofresistive contact21 within the heating zone. This may, for example, allow the heating zone to reach a higher temperature, a more controllable temperature, a more consistent temperature around its circumference and/or may allow the production of a wider heating zone.
• In embodiments in which theheater3 comprises a plurality of temperature-sensitive elements17, theheater3 may comprise an arrangement for coupling the temperature-sensitive elements to improve the consistency and uniformity of the alteration of the shape of the bimetallic strips and/or shape memory materials, and consequently to ensure that a narrow heating zone is established. For example, in some embodiments, the temperature-sensitive elements17 may comprisebimetallic strips18 which are coupled to one another by means of a plurality of electrically non-conductive spacers, thus forming a ring of spacers around thecylindrical element19. Bending of thebimetallic strips18 may cause the ring of spacers to rotate relative to thecylindrical element19.
• The region of theheater3 that is immediately in-front of the heating zone, into which the heating zone is progressing, may be pre-heated by longitudinal thermal conduction from the heating zone. This region may comprise a pre-volatilizing region of theheater3, which heats up thesmokeable material5 in preparation for its components to be volatilized by the approaching heating zone. This pre-heating does not heat thesmokeable material5 to a sufficient temperature to volatilize nicotine. A suitable temperature could be less than 120° C., such as approximately 100° C.
• In heaters comprising a plurality of temperature-sensitive elements17, this pre-heating zone may be enhanced and controlled by the use of a plurality of temperature-sensitive elements17. For example, the plurality of temperature-sensitive elements17 may be configured to bend at different rates, or at the same rate, but with different starting positions alongcylindrical element19. Thus, a first heating zone may be established by at least one temperature-sensitive element17A at a point ofresistive contact21A at a first longitudinal position along thecylindrical element19, and a second heating zone may be established by at least one temperature-sensitive element17B at a point ofresistive contact21B at a second longitudinal position along thecylindrical element19. In these embodiments, the first heating zone may be at a lower temperature than the second heating zone. This may be achieved, for example, by a lower electrical current in the first heating zone relative to that of the second heating zone. Alternatively, the second heating zone may comprise a larger number of temperature-sensitive elements17B than are present in relation to the first heating zone.
• FIG. 6 illustrates an embodiment in which theheater3 comprises heating and pre-heating zones. The embodiment ofFIG. 6 operates in substantially the same manner as theheater3 described above in respect ofFIG. 3.
• The difference between theheater3 ofFIG. 6 and that ofFIG. 3 is that theheater3 ofFIG. 6 comprises two temperature-sensitive elements17A,17B, each comprising abimetallic strip18A,18B. A firstresistive contact point21A is formed between one temperature-sensitive element17A and thecylindrical element19. A secondresistive contact point21B is formed between the other temperature-sensitive element17B and thecylindrical element19. The firstresistive contact point21A is closer to thefirst end20 of thecylindrical element19 than is the secondresistive contact point21B.
• Thus, when theheater3 is in use, thefirst heating zone22, formed at the position of the firstresistive contact point21A, is axially displaced towards thefirst end20 of theheater3 relative to thesecond heating zone23, formed at the position of the secondresistive contact point21B.
• In the embodiment shown inFIG. 6, theheater3 is configured such that the current supplied to the one temperature-sensitive element17A is greater than that supplied to the other temperature-sensitive element17B. As a result, the electrical resistance at the firstresistive contact point21A is greater than that at the secondresistive contact point21B, and thus the temperature of thefirst heating zone22 is greater than that of thesecond heating zone23.
• In the embodiments ofFIGS. 1 to 6, theheater3 comprises acylindrical element19, the central longitudinal cavity of which comprises theheating chamber4. In other embodiments, the cylindrical element and the heating chamber components are separate. Such an embodiment is shown inFIG. 7.
• FIG. 7 illustrates an embodiment in which theheater3 comprises a plurality of temperature-sensitive elements17A,17B. The embodiment ofFIG. 7 operates in substantially the same manner as theheater3 described above in respect ofFIG. 3.
• The difference between theheater3 ofFIG. 7 and that ofFIG. 3 is that theheater3 ofFIG. 7 comprises two temperature-sensitive elements17A,17B, each comprising abimetallic strip18A,18B. The two temperature-sensitive elements17A,17B are electrically connected to one another via a central cylindrical heat-distributor24. The contacts between the temperature-sensitive elements17A,17B and the central cylindrical heat-distributor24 comprise electrically resistive contact points21A,21B. The resistive contact points21A,21B are diametrically opposite each other across the central cylindrical heat-distributor24. Unlike thecylindrical elements19 referred to previously, the centralcylindrical heat distributor24 is not directly coupled to theenergy source2.
• The central cylindrical heat-distributor24 comprises a material having a high electrical resistance, such as nichrome. Due to the high resistance, the electric current passing between the temperature-sensitive elements17A,17B generates heat in the central cylindrical heat-distributor24.
• Thebimetallic strips18A,18B within the temperature-sensitive elements17A,17B may have the same composition and thus alter their shape in the same way as they are heated. As a result, the electrically resistive contact points21A,21B may remain diametrically opposite each other across the central cylindrical heat-distributor24 as the temperature-sensitive elements17A,17B bend. Anarrow heating zone22 is thereby formed about the circumference of the central cylindrical heat-distributor24, at a longitudinal position corresponding to that of the resistive contact points21A,21B.
• A pre-heatingzone25 may be established by means of heat distribution axially along the central cylindrical heat-distributor24. The thermal conductivity of the central cylindrical heat-distributor24 will determine the size and temperature of the pre-heatingzone25.
• In general, in apparatus of the type described herein, the length of thehousing7 may be approximately 130 mm, the length of the energy source may be approximately 59 mm, and the length of theheater3 andheating region4 may be approximately 50 mm. Other embodiments may have different dimensions. The diameter of thehousing7 may be between approximately 15 mm and approximately 18 mm. For example, the diameter of the housing's first end8 may be 18 mm whilst the diameter of themouthpiece6 at the housing'ssecond end9 may be 15 mm. The depth of theheating chamber4 may be approximately 5 mm and theheating chamber4 may have an exterior diameter of approximately 10 mm at its outwardly-facing surface. The diameter of theenergy source2 may be between approximately 14 mm and approximately 15 mm, such as for example 14.6 mm.
• In general, the heaters may or may not be reusable, or may be reusable only with a new charge ofsmokeable material5. In some embodiments, once switched off or consumed, if theapparatus1 is to be reused, theheater3 may be replaced.
• In embodiments comprising a bi-metallic strip, theheater3 may continue to progressively heat the charge of smokeable material until thebimetallic strip18 has been bent as fully as possible, until the heating zone has migrated along the entire length of theheater3, or until the supply of electrical current is terminated. Theapparatus1 may comprise an arrangement by which the supply of electrical current is terminated once thebimetallic strip18 has been bent as fully as possible.
• In embodiments comprising a shape memory material, the heater may continue to progressively heat the charge of smokeable material until all of the shape memory material has been heated above the transition temperature and altered in shape, until the heating zone has migrated along the entire length of theheater3, or until the supply of electrical current is terminated. Theapparatus1 may comprise an arrangement by which the supply of electrical current is terminated once all of the shape memory material has been transformed.
• In general, theheater3 may be restarted if the electrical current is reinstated, provided that the resistive contact between theelements17,19,24 is sufficient to restart the process. However, because the temperature-sensitive element17 may return to its original shape as it cools, the heating zone may restart from thefirst end20 of theheater3. To avoid this, theheater3 may comprise an arrangement which prevents the temperature-sensitive element17 from reverting to its original shape when cooled.
• In some embodiments, the apparatus may comprise heater arrangements different from those described, which nevertheless work in accordance with the same principle and offer the same advantages as those relating to the embodiments described above.
• In some embodiments, for example, theapparatus1 may comprise a plurality ofheaters3 of the type described above, which may be arranged in coaxial alignment. For example, the apparatus may comprise any suitable number of heaters, such as two, three, four, five, six, eight, ten, twelve, or more heaters.
• In general, the plurality ofelements17,19 may be made of any electrically conductive material, such as copper for example. Theelements17,19 may be made of the same or different materials. Generally, theelements17,19 should be durable and not consumed during the operation of theheater3. However, single use is also envisaged.
• The mass of thesmokeable material5 which is heated by theheater3 may be in the range of 0.2 to 1 g. The temperature to which thesmokeable material5 is heated may be user controllable, for example to any temperature within the temperature range of 120° C. to 250° C., as previously described. The temperature to which thesmokeable material5 is heated to volatilize components of thesmokeable material5 may be, for example, any temperature within the temperature range of 120° C. to 250° C., as previously described. The mass of theapparatus1 as a whole may be in the range of 70 to 125 g, although a smaller mass is also possible. Anexample battery2 has a capacity of 1000 to 3000 mAh and a voltage of 3.7V.
• In some embodiments, thesmokeable material5 may be comprised in a cartridge which can be inserted into the heating chamber. For example, as shown inFIGS. 1 and 2, the cartridge may comprise asmokeable material rod5 which can be introduced into theapparatus1 by removal of themouthpiece6 and insertion against thebuffer16. The smokeable material cartridge fits within theheater3 so that the circumferential surface of thesmokeable material rod5 faces the internal surface of theheater3, such that theheater3 is a close fit around therod5 to ensure efficient heat transfer. Thecartridge5 is generally not longer than theheater3 and may be approximately equal to the length of theheater3 so that theheater3 can heat thesmokeable material5 along its entire length.
• In some embodiments, thethermal insulation11 may be provided as part of thesmokeable material cartridge5, located co-axially around the outside of theheater3.
• An advantage of theapparatus1, and in particular theheater3, is that there is no requirement for a dedicated control system to regulate the heating of thesmokeable material5, and/or to adjust the section of smokeable material that is being heated. Instead, once the disclosed apparatus is activated, a small section of thesmokeable material5 is heated and the area of heating migrates at a substantially constant rate from one end of thesmokeable material5 to the other. Furthermore, the degree of heat and the rate of migration can easily be controlled and predetermined by adjusting the composition and arrangement of theheater3.
• A further advantage of this arrangement is that activating only a small portion of theheater3 means that the energy required to heat thesmokeable material5 is reduced in comparison to that required to heat the full amount of smokeable material over the entire period of use of theapparatus1.
• A further advantage is that once activated the apparatus is permanently ready and able to provide smokeable material components to the user because the smokeable material is continually being heated. This allows the aromatics, and nicotine if present, to be inhaled by the user without substantial delay, for example, whilst a heater is activated to heat the smokeable material in response to detection of the user drawing on the apparatus.
• In order to address various issues and advance the art, the entirety of this disclosure shows by way of illustration and example various embodiments in which the claimed invention may be practised and which provide for a superior apparatus arranged to heat but not burn smokable material. The advantages and features of the disclosure are of a representative sample of embodiments only, and are not exhaustive and/or exclusive. They are presented only to assist in understanding and teach the claimed and otherwise disclosed features. It is to be understood that advantages, embodiments, examples, functions, features, structures and/or other aspects of the disclosure are not to be considered limitations on the disclosure as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the scope and/or spirit of the disclosure. Various embodiments may suitably comprise, consist of, or consist in essence of, various combinations of the disclosed elements, components, features, parts, steps, means, etc. The disclosure may include other inventions not presently claimed, but which may be claimed in future.

Claims (15)

1. An apparatus configured to heat smokeable material to volatilize at least one component of the smokeable material, wherein the apparatus comprises a heater with a temperature-sensitive element configured to alter its shape when heated in order to cause progressive heating of the smokeable material.

2. The apparatus according toclaim 1, wherein the heater is configured to trigger alteration of the shape of the temperature-sensitive element.

3. The apparatus according toclaim 1, wherein the heater is configured to trigger alteration of the shape of the temperature-sensitive element in response to a user action.

4. The apparatus according toclaim 1, configured to trigger alteration of the shape of the temperature-sensitive element by causing an electrical current to pass through the temperature-sensitive element.

5. The apparatus according toclaim 1, configured to resistively heat the temperature-sensitive element to cause alteration of the shape of the temperature-sensitive element.

6. The apparatus according toclaim 1, wherein the heater is configured to provide an area of elevated temperature which migrates progressively along the heater as the temperature-sensitive element alters in shape.

7. The apparatus according toclaim 1, wherein the heater comprises an electrode comprising the temperature-sensitive element.

8. The apparatus according toclaim 7, wherein the heater is configured to form an electrically resistive contact comprising the electrode.

9. The apparatus according toclaim 8, wherein the electrically resistive contact changes position relative to the smokeable material upon alteration of the shape of the temperature-sensitive element.

10. The apparatus according toclaim 7, wherein the heater comprises a plurality of electrical elements, and wherein one or more of the electrical elements comprises the temperature-sensitive element.

11. The apparatus according toclaim 10, wherein the heater is configured to alter the position and/or shape of one or more of the electrical elements upon alteration of the shape of the temperature-sensitive element.

12. The apparatus according toclaim 1, wherein the apparatus comprises a plurality of temperature-sensitive elements and the temperature-sensitive elements form electrically resistive contact points at a plurality of different distances from a first end of the heater.

13. The apparatus according toclaim 1, wherein the temperature-sensitive element comprises a bimetallic strip.

14. The apparatus according toclaim 1, wherein the temperature-sensitive element comprises a shape memory material.

15. The apparatus according toclaim 1, wherein the apparatus is configured to heat the smokeable material without combusting the smokeable material.

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