US20150181935A1

US20150181935A1 - Apparatus for Heating Smokeable Material

Info

Publication number: US20150181935A1
Application number: US14/142,541
Authority: US
Inventors: Alex Lyubomirskiy; Sergei Ikovenko
Original assignee: British American Tobacco Investments Ltd
Current assignee: British American Tobacco Investments Ltd
Priority date: 2013-12-27
Filing date: 2013-12-27
Publication date: 2015-07-02

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 of FIG. 1;

FIG. 3A is a diagram illustrating the heater assembly shown in FIG. 1 prior to use;

FIG. 3B is a diagram illustrating the heater assembly shown in FIG. 1 in use at a first time point;

FIG. 3C is a diagram illustrating the heater assembly shown in FIG. 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 in FIG. 1, the apparatus 1 comprises an energy source 2, a heater 3, and a heating chamber 4, which contains smokeable material 5.
The energy source 2 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. The energy source 2 may be rechargeable. The energy source 2 is electrically coupled to the heater 3 to supply electrical energy to the heater 3 when required.
The heating chamber 4 is configured to receive smokeable material 5 so that the smokeable material 5 can be heated in the heating chamber 4. The heater 3 and heating chamber 4 are arranged so that the heater 3 is able to heat the heating chamber 4. Generally, and in the embodiment shown in FIG. 1, the heating chamber 4 is located adjacent to the heater 3 so that thermal energy from the heater 3 heats the smokeable material 5 in the heating chamber 4. The heater 3 heats the heating chamber 4 sufficiently to volatilize aromatic compounds and nicotine if present in the smokeable material 5 without burning the smokeable material 5.
In the embodiment shown in FIG. 1, the heater 3 is in the form of a substantially cylindrical, elongate rod, which extends along part of a central longitudinal axis of the apparatus 1, towards the mouth end. The heating chamber 4 is located around the circumferential, longitudinal surface of the heater 3. The smokeable material 5 is in the form of a hollow, annular cylinder which fits within the heating chamber 4. The smokeable material 5 is located within the apparatus 1 such that the heater 3 is positioned within the central longitudinal cavity of the smokeable material 5. The smokeable material 5 thus fits closely around the heater 3 to ensure efficient heat transfer from the heater 3 to the smokeable material 5. The heating chamber 4 and smokeable material 5 therefore comprise co-axial layers around the heater 3. However, as will be evident from the discussion below, in other embodiments, other shapes and configurations of the heater 3, heating chamber 4, and smokeable material 5 can alternatively be used.
In the embodiment shown in FIG. 1, the smokeable material 5 comprises a tobacco blend, or some other volatisable material.
FIG. 2 is an exploded diagram of the apparatus shown in FIG. 1. As shown in FIG. 2, the apparatus 1 further comprises an annular mouthpiece 6 and a housing 7 in which the components of the apparatus 1 such as the energy source 2 and heater 3 are contained.
In the embodiment shown, the housing 7 comprises an approximately cylindrical tube with the energy source 2 located towards its first end 8, and the heater 3 and heating chamber 4 located towards its opposite, second end 9. As shown in FIG. 1, the energy source 2 and heater 3 are aligned along a central longitudinal axis of the housing 7.
The mouthpiece 6 attaches to the second end 9 of the housing 7, which may also be considered to be the mouth end of the apparatus 1. The mouthpiece 6 is located adjacent to the heating chamber 4 and smokeable material 5, such that the annular mouthpiece 6 provides a passageway 10 for fluid communication between the mouth of the user and the heating chamber 4.
Thermal insulation 11 is provided between the heater 3 and the housing 7 to reduce heat loss from the apparatus 1 and therefore improve the efficiency with which the smokeable material 5 is heated. In the embodiment shown in FIGS. 1 and 2, a layer of thermal insulation 11, comprising a substantially tubular length of insulation 11, is located co-axially around the heater 3.
As shown in FIG. 2, the layer of thermal insulation 11 in this example comprises vacuum insulation, and in particular in this example comprises a double-wall arrangement 12 enclosing an internal region 13. An example of a suitable material for the double wall arrangement 12 is stainless steel and an example of a suitable thickness for the walls of the double wall arrangement 12 is approximately 100 μm. The internal region or core 13 of the insulation 11 comprises a void. In other embodiments, the internal region 13 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 the internal region 13 is generally in the range of 0.1 to 0.001 mbar. The thermal conductivity of the thermal insulation 11 is generally in the range of 0.004 to 0.005 W/mK.
A reflective coating may be applied to the internal surfaces of the double wall arrangement 12 to further reduce heat losses through the thermal insulation 11.
The coating may, for example, comprise an aluminium infrared (IR) reflective coating.
The apparatus 1 comprises air conduits 14, which allow external air to be drawn into the housing 7 and through the heating chamber 4 when the apparatus 1 is in use. The air conduits 14 comprise apertures 14 in the housing 7 which are located upstream from the smokeable material 5 and heating chamber 4 towards the first end 8 of the housing 7. The air conduits 14 may also allow any excess heat from the energy source 2 to be dissipated.
The heating chamber 4 may comprise one or more inlet valves 15 which, when closed, prevent gaseous flow from the air conduits 14 into the heating chamber 4. The valves 15 thereby reduce the diffusion of air and smokeable material flavours from the heating chamber 4, as discussed in more detail below. The valves 15 may be located within a cylindrical buffer 16 which is positioned at the end of the heating chamber 4 towards the first end 8 of the housing 7. More specifically, the cylindrical buffer 16 may be positioned to separate the energy source 2 and air conduits 14 on one side, from the heater 3, heating chamber 4, and smokeable material 5 on the other side of the cylindrical buffer 16. The buffer 16 thereby provides heat insulation between the energy source 2 and the heater 3 to prevent direct transfer of heat from one to the other. The buffer 16 also comprises an arrangement (not shown) for electrically coupling the heater 3 to the power source 2.
An example of the heater 3 is shown in detail in FIG. 3A. The heater 3 comprises a temperature-sensitive element 17 in the form of a bimetallic strip 18.
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 the bimetallic strip 18 which occurs as the strip is heated or cooled. The degree of curvature of the bimetallic strip 18 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 the bimetallic strip 18 may be proportional to the magnitude of the alteration in temperature.
The bimetallic strip 18 may function as an electrical conductor within the temperature-sensitive element 17. In addition, or alternatively, the temperature-sensitive element 17 may comprise a separate electrical conductor, wherein, in combination, the bimetallic strip 18 and electrical conductor are arranged such that the shape and/or position of the electrical conductor may be altered by the bending of the bimetallic strip 18.
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, the bimetallic strip 18 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 the bimetallic strip 18 functions as an electrical conductor within the temperature-sensitive element 17, bimetallic strips comprising a metal that is a particularly good conductor of electricity, such as copper, may be used.
The heater 3 also comprises a central cylindrical element 19. The cylindrical element 19 has an annular configuration and in essence is in the form of an elongated tube, a central longitudinal cavity of which forms the heating chamber 4.
In the embodiment shown, a cavity is provided between the outer surface of the heater 3 and the cylindrical element 19. The temperature-sensitive element 17 is positioned within the cavity and is arranged to contact the outer surface of the cylindrical element 19. Alteration of the shape of the temperature-sensitive element 17 alters the position of contact between the temperature-sensitive element 17 and the cylindrical element 19. Contact between the temperature-sensitive element 17 and the cylindrical element 19 may be electrically resistive such that, in use, the cylindrical element 19 is heated in the position at which it contacts the temperature-sensitive element 17.
In general, the cylindrical element 19 may be composed of any material that is both electrically and thermally conductive. Electrical conductivity allows the cylindrical element 19 to form part of an electrical circuit, for example with the temperature-sensitive element 17. Thermal conductivity allows heat generated by resistive contact with the temperature-sensitive element 17 on an outer surface of the cylindrical element 19 to be transmitted into the heating chamber 4 within the cylindrical element 19. It may also be desirable for heat to be conducted circumferentially around the cylindrical element 19.
In the embodiment shown, the cylindrical element 19 is made of aluminium or copper. However, the cylindrical element 19 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 the cylindrical element 19 may be thermally conductive in a circumferential direction to allow efficient heat transfer from a resistive contact point 21 around the heating chamber 4, it may be desirable that thermal conduction along the length of the cylindrical element 19 is minimised to ensure that only a short longitudinal section of the heating chamber 4 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 the cylindrical element 19. To minimise the effect of thermal conduction longitudinally along the cylindrical element 19, the cylindrical element 19 may have a greater capacity to conduct thermal energy circumferentially around the heating chamber 4 than longitudinally along the heating chamber 4. The cylindrical element 19 may inherently possess this directional thermal conductivity, or may comprise a lining having suitable properties of thermal conductivity. For example, the cylindrical element 19 may comprise a plurality of individual panels of aluminium arranged longitudinally along the inner surface of the cylindrical element 19. The panels may be bonded together and/or bonded to the cylindrical element 19 using a thermally insulating bonding agent. Other arrangements may be used. For example, instead of comprising individual panels, the cylindrical element 19 may comprise an electrically and thermally conductive material that is coiled around the heating chamber 4.
The temperature-sensitive element 17 may extend substantially along the entire length of the cylindrical element 19.
Prior to use of the apparatus 1, the temperature-sensitive element 17 is only in contact with the cylindrical element 19 at a position close to a first end 20 of the cylindrical element, as shown in FIG. 3A.
In use, contact between the temperature-sensitive and cylindrical elements 17, 19 is electrically resistive. As used herein, an electrically resistive contact is a point of contact between the elements 17, 19. Electrical resistance at the contact point generates heat in the region of contact, which is dissipated into the temperature sensitive element 17 and the cylindrical element 19.
The bimetallic strip 18 of the temperature-sensitive element 17 is configured to bend when heated such that, when the apparatus is in use, resistive contact between the temperature-sensitive and cylindrical elements 17, 19 causes the bimetallic strip to alter in shape. This alteration in shape causes the location of the resistive contact with the cylindrical element 19 to change. In particular, as illustrated in FIGS. 3A to 3C, the location of resistive contact may be caused to progress longitudinally along the cylindrical element 19. In this way, heat may be transmitted into the cylindrical element 19 at any particular longitudinal position along its length. This is described in more detail below.
The temperature-sensitive and cylindrical elements 17, 19 are electrically coupled to the energy source 2, which causes electrical current to flow through the elements 17, 19 and create the resistive heating effect referred to above. The electrical coupling between one or both of the elements 17, 19 and the energy source 2 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 the apparatus 1 or may be puff-activated.
In use, as the temperature-sensitive element 17 is resistively heated, the bimetallic strip 18 bends, and the position at which the temperature-sensitive element 17 contacts the cylindrical element 19 is altered. The new position of resistive contact heats a new section of the temperature-sensitive element 17, which causes further bending of the bimetallic strip 18 and further alteration of the position at which the temperature-sensitive element 17 contacts the cylindrical element 19. In this way, the position of resistive contact between the temperature-sensitive and cylindrical elements 17, 19 may move progressively along the cylindrical element 19, driven by resistive contact between the elements 17, 19 and the curvature of the bimetallic strip 18. This process is illustrated in FIGS. 3B and 3C.
The heater 3 in use at a first time point is shown in FIG. 3B, and in use at a second time point is shown in FIG. 3C, wherein the second time point is later than the first time point. As shown in FIG. 3B, the temperature-sensitive and cylindrical elements 17, 19 are in resistive contact, and the electrical current passing between the elements 17, 19 generates heat in the region of the point of contact 21. The region of the cylindrical element 19 that is resistively heated forms the heating zone 22. The heat generated by the resistive contact 21 is conducted into the temperature-sensitive element 17 and causes the bimetallic strip 18 to begin to bend and alter its shape in the adjacent region. As shown in FIG. 3C, curvature of the bimetallic strip 18 alters the relative positions of the elements 17, 19, forming a new region of resistive contact 21′ between the elements 17, 19, and a new heating zone 23. The bending of the bimetallic strip 18 thereby continues, gradually altering the shape of the temperature-sensitive element 17 from one end of the heater 3 to the other, and thus gradually forming new points of resistive contact between the elements 17, 19 from one end of the heater 3 to the other. The position of heat-generating resistive contact between the elements 17, 19 and the heating zone thus migrates, preferably at a substantially constant rate, along the length of the heater 3.
By this arrangement, the heater 3 provides heat in a narrow circumferential band, referred to as the heating zones 22, 23, around the heater 3, in a position substantially corresponding to the position of resistive contact 21, 21′, between the elements 17, 19. Because heating occurs only at the point of resistive contact 21, 21′ between the elements 17, 19, the heating zone provided by the heater 3 is relatively narrow. That is, only a relatively small portion of the longitudinal length of the heater 3 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 the cylindrical element 19, and may be, for example, 10%, 20% or 40% of the total surface area of the cylindrical element 19.
The width of the heating zones 22, 23 (that is, the longitudinal extension of the heating zone along the heater 3) may in general be influenced by a number of factors. For example, the capacity of the temperature-sensitive element 17 to conduct heat, the capacity of the bimetallic strip 18 to bend, the rate of migration of the heating zone, the current provided by the energy source 2, and the nature of the resistive contact between the elements 17, 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 the energy source 2 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 the bimetallic strip 18 has been bent as fully as possible, until the heating zone has migrated along the entire length of the heater 3, or until the supply of electrical current is terminated. The apparatus 1 may comprise an arrangement by which the supply of electrical current is terminated once the bimetallic strip 18 has been bent as fully as possible.
In use, the apparatus 1 provides volatilized smokeable material compounds for inhalation by the user via the mouthpiece 6.
To use the apparatus 1, the user activates the heater 3 as described above using the switch. As shown in FIG. 1 and discussed above, the heating chamber 4 and smokeable material 5 may be located in a central region of the housing 7, and the heater 3 may be located around the longitudinal surface of the heating chamber 4. In this arrangement, in use, thermal energy emitted by the resistive contact in the heater 3 travels in a radial direction inwards from the longitudinal internal surface of the cylindrical element 19 into the heating chamber 4 and the smokeable material 5.
The heater 3 is arranged so that the heating zone produced by the heater 3 migrates towards the second, mouth end 9 of the apparatus 1.
Because the heater 3 provides a narrow circumferential heating zone, it supplies thermal energy to the smokeable material 5 located radially adjacent to that region of the heater 3 without substantially heating the remainder of the smokeable material 5. The heated section of smokeable material 5 may comprise a section or ring of smokeable material 5 which lies directly circumferentially adjacent to the heating zone produced by the heater 3. In this way, a small distinct section of the smokeable material 5 can be heated individually. The section of smokeable material 5 that is heated has a mass and volume which is significantly less than the body of smokeable material 5 as a whole. Furthermore, since the heating zone produced by the heater 3 migrates progressively along the longitudinal length of the heater 3, the specific section of smokeable material 5 being heated also migrates progressively along the length of the smokeable material 5, and the precise section of smokeable material 5 that is being heated is continually changing.
If the smokeable material 5 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 the heater 3 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 the heater 3, which heats up the smokeable material 5 in preparation for its components to be volatilized by the approaching heating zone. This pre-heating does not heat the smokeable material 5 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 the heater 3 has been activated, the smokeable material 5 is heated and the user may obtain volatilized smokeable material compounds by drawing on the mouthpiece 6 of the apparatus 1. As the user draws on the mouthpiece 6, air is drawn into the heating chamber 4 of the apparatus 1 via the air conduits 14 and the one or more valves 15. As it is drawn through the heated smokeable material 5 in the heating chamber 4, the air is enriched with smokeable material vapours, such as aroma vapours, before being inhaled by the user at the mouthpiece 6.
Between draws, the valves 15 may be closed so that all volatilized substances remain contained inside the chamber 4 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 the heating chamber 4. This helps to ensure that the delivery of volatilized nicotine and aromatic compounds remains constant throughout the use of the smoking article. The valves 15 open as the user draws on the mouthpiece 6 so that gaseous flow may be drawn through the heating chamber 4 to carry volatilized smokeable material components to the user via the mouthpiece 6. In some embodiments, a membrane may be located in the valves 15 to ensure that no oxygen enters the chamber 4. The valves 15 may be breath-actuated so that they open when the user draws on the mouthpiece 6. The valves 15 may close when the user stops drawing. Alternatively, the valves 15 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 the valve 15 opens and closes automatically.
FIG. 4 shows an embodiment in which the temperature-sensitive elements 17 comprise a shape memory material. The heater 3 shown in FIG. 4 operates in substantially the same manner as the heater 3 described above with reference to FIGS. 1-3, and is suitable for use in an apparatus 1 as described above with reference to FIGS. 1-3. The difference between the embodiment of FIG. 4 and the embodiment shown in FIGS. 1-3 is that the temperature-sensitive elements 17 of the heater 3 comprise a shape memory material 28 instead of a bimetallic strip 18.
The shape memory material 28 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 the shape memory material 28 which occurs as the strip is heated. The shape memory material 28 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 the smokeable material 5. 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.
The shape memory material 28 may function as an electrical conductor within the temperature-sensitive element 17. For example, the shape memory material 28 may comprise an electrically conductive shape memory alloy. In addition, or alternatively, the temperature-sensitive element 17 may comprise a separate electrical conductor, wherein, in combination, the shape memory material 28 and electrical conductor are arranged such that the shape and/or position of the electrical conductor may be changed by the transformation of the shape memory alloy 28. 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, the shape memory material 28 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. The shape memory material 28 may alternatively, or in addition, comprise a shape memory polymer.
The heater 3 also comprises a central cylindrical element 19. The cylindrical element 19 may be the same as that shown in FIG. 3, in which case the same considerations regarding the cylindrical element 19 apply as were discussed above in relation to the embodiment of FIG. 3.
In the embodiment shown, a cavity is provided between the outer surface of the heater 3 and the cylindrical element 19. The temperature-sensitive element 17 is positioned within the cavity and is arranged to contact the outer surface of the cylindrical element 19. Alteration of the shape of the temperature-sensitive element 17 alters the position of contact between the temperature-sensitive element 17 and the cylindrical element 19.
The temperature-sensitive elements 17 extend substantially along the entire length of the cylindrical element 19. Prior to use of the apparatus 1, the temperature-sensitive elements 17 are only in contact with the cylindrical element 19 at a position close to a first end 20 of the cylindrical element, as shown in FIG. 4A.
In use, points of contact 21 between the temperature-sensitive and cylindrical elements 17, 19 are electrically resistive. When a current is passed between the temperature-sensitive and cylindrical elements 17, 19, the resistive contact heats the shape memory material 28 to a temperature above the transition temperature, causing the temperature-sensitive elements 17 to alter their shape in the region of the points of resistive contact 21. Transformation of the shape memory material 28 causes the position at which the temperature-sensitive element 17 contacts the cylindrical elements 19 to be altered. The new position of resistive contact heats a new section of the temperature-sensitive element 17, which causes alteration of the shape of a new section of shape memory material 28, and further alteration of the position at which the temperature-sensitive element 17 contacts the cylindrical element 19. In this way, the position of resistive contact between the temperature-sensitive and cylindrical elements 17, 19 may move progressively along the cylindrical element 19, driven by resistive contact between the elements and the transformation of the shape memory material 28. This process is illustrated in FIGS. 4B and 4C.
The heater 3 in use at a first time point is shown in FIG. 4B, and in use at a second time point is shown in FIG. 4C, wherein the second time point is later than the first time point. As shown in FIG. 4B, the temperature-sensitive and cylindrical elements 17, 19 are in resistive contact, and the electrical current passing between the elements 17, 19 generates heat in the region of the point of contact 21. This heated region is heating zone 22. The heat generated by the resistive contact 21 heats the adjacent section of shape memory material 28 above the transition temperature and thereby causes the shape memory material 28 to begin to alter its shape in the adjacent region. Transformation of the shape memory material 28 alters the relative positions of the elements 17, 19, forming a new region of resistive contact 21′ between the elements 17, 19, and a new heating zone 23. The transformation of the shape memory material thereby continues, gradually altering the shape of the temperature-sensitive element 17 from one end of the heater 3 to the other, and thus gradually forming new points of resistive contact between the elements 17, 19 from one end of the heater 3 to the other. The position of heat-generating resistive contact 21 between the elements 17, 19 and the heating zone thus migrates at a substantially constant rate along the length of the heater 3.
In the embodiment shown in FIG. 4, the heater 3 comprises two temperature-sensitive elements 17, each comprising a shape memory material 28. In some embodiments, the heater 3 may comprise a plurality of temperature-sensitive elements 17, each comprising a bimetallic strip 18 or shape memory alloy 28. In some embodiments, the heater 3 may comprise a plurality of temperature-sensitive elements 17, one or more of which comprises a bimetallic strip 18 and one or more of which comprises a shape memory alloy 28.
Examples of such arrangements are shown in FIG. 4, in which the heater 3 comprises two temperature-sensitive elements 17, each comprising a shape memory material 28, and in FIG. 5, in which the heater 3 comprises six temperature-sensitive elements 17, each comprising a bimetallic strip 18.
The use of a plurality of temperature-sensitive elements 17 may offer a number of advantages. With reference to the embodiment shown in FIG. 5, since there are six temperature-sensitive elements 17, there are six points of resistive contact 21 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 the heater 3 comprises a plurality of temperature-sensitive elements 17, the heater 3 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 elements 17 may comprise bimetallic strips 18 which are coupled to one another by means of a plurality of electrically non-conductive spacers, thus forming a ring of spacers around the cylindrical element 19. Bending of the bimetallic strips 18 may cause the ring of spacers to rotate relative to the cylindrical element 19.
The region of the heater 3 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 the heater 3, which heats up the smokeable material 5 in preparation for its components to be volatilized by the approaching heating zone. This pre-heating does not heat the smokeable material 5 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 elements 17, this pre-heating zone may be enhanced and controlled by the use of a plurality of temperature-sensitive elements 17. For example, the plurality of temperature-sensitive elements 17 may be configured to bend at different rates, or at the same rate, but with different starting positions along cylindrical element 19. Thus, a first heating zone may be established by at least one temperature-sensitive element 17A at a point of resistive contact 21A at a first longitudinal position along the cylindrical element 19, and a second heating zone may be established by at least one temperature-sensitive element 17B at a point of resistive contact 21B at a second longitudinal position along the cylindrical element 19. 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 elements 17B than are present in relation to the first heating zone.
FIG. 6 illustrates an embodiment in which the heater 3 comprises heating and pre-heating zones. The embodiment of FIG. 6 operates in substantially the same manner as the heater 3 described above in respect of FIG. 3.
The difference between the heater 3 of FIG. 6 and that of FIG. 3 is that the heater 3 of FIG. 6 comprises two temperature- sensitive elements 17A, 17B, each comprising a bimetallic strip 18A, 18B. A first resistive contact point 21A is formed between one temperature-sensitive element 17A and the cylindrical element 19. A second resistive contact point 21B is formed between the other temperature-sensitive element 17B and the cylindrical element 19. The first resistive contact point 21A is closer to the first end 20 of the cylindrical element 19 than is the second resistive contact point 21B.
Thus, when the heater 3 is in use, the first heating zone 22, formed at the position of the first resistive contact point 21A, is axially displaced towards the first end 20 of the heater 3 relative to the second heating zone 23, formed at the position of the second resistive contact point 21B.
In the embodiment shown in FIG. 6, the heater 3 is configured such that the current supplied to the one temperature-sensitive element 17A is greater than that supplied to the other temperature-sensitive element 17B. As a result, the electrical resistance at the first resistive contact point 21A is greater than that at the second resistive contact point 21B, and thus the temperature of the first heating zone 22 is greater than that of the second heating zone 23.
In the embodiments of FIGS. 1 to 6, the heater 3 comprises a cylindrical element 19, the central longitudinal cavity of which comprises the heating chamber 4. In other embodiments, the cylindrical element and the heating chamber components are separate. Such an embodiment is shown in FIG. 7.
FIG. 7 illustrates an embodiment in which the heater 3 comprises a plurality of temperature- sensitive elements 17A, 17B. The embodiment of FIG. 7 operates in substantially the same manner as the heater 3 described above in respect of FIG. 3.
The difference between the heater 3 of FIG. 7 and that of FIG. 3 is that the heater 3 of FIG. 7 comprises two temperature- sensitive elements 17A, 17B, each comprising a bimetallic strip 18A, 18B. The two temperature- sensitive elements 17A, 17B are electrically connected to one another via a central cylindrical heat-distributor 24. The contacts between the temperature- sensitive elements 17A, 17B and the central cylindrical heat-distributor 24 comprise electrically resistive contact points 21A, 21B. The resistive contact points 21A, 21B are diametrically opposite each other across the central cylindrical heat-distributor 24. Unlike the cylindrical elements 19 referred to previously, the central cylindrical heat distributor 24 is not directly coupled to the energy source 2.
The central cylindrical heat-distributor 24 comprises a material having a high electrical resistance, such as nichrome. Due to the high resistance, the electric current passing between the temperature- sensitive elements 17A, 17B generates heat in the central cylindrical heat-distributor 24.
The bimetallic strips 18A, 18B within the temperature- sensitive elements 17A, 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 points 21A, 21B may remain diametrically opposite each other across the central cylindrical heat-distributor 24 as the temperature- sensitive elements 17A, 17B bend. A narrow heating zone 22 is thereby formed about the circumference of the central cylindrical heat-distributor 24, at a longitudinal position corresponding to that of the resistive contact points 21A, 21B.
A pre-heating zone 25 may be established by means of heat distribution axially along the central cylindrical heat-distributor 24. The thermal conductivity of the central cylindrical heat-distributor 24 will determine the size and temperature of the pre-heating zone 25.
In general, in apparatus of the type described herein, the length of the housing 7 may be approximately 130 mm, the length of the energy source may be approximately 59 mm, and the length of the heater 3 and heating region 4 may be approximately 50 mm. Other embodiments may have different dimensions. The diameter of the housing 7 may be between approximately 15 mm and approximately 18 mm. For example, the diameter of the housing's first end 8 may be 18 mm whilst the diameter of the mouthpiece 6 at the housing's second end 9 may be 15 mm. The depth of the heating chamber 4 may be approximately 5 mm and the heating chamber 4 may have an exterior diameter of approximately 10 mm at its outwardly-facing surface. The diameter of the energy source 2 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 of smokeable material 5. In some embodiments, once switched off or consumed, if the apparatus 1 is to be reused, the heater 3 may be replaced.
In embodiments comprising a bi-metallic strip, the heater 3 may continue to progressively heat the charge of smokeable material until the bimetallic strip 18 has been bent as fully as possible, until the heating zone has migrated along the entire length of the heater 3, or until the supply of electrical current is terminated. The apparatus 1 may comprise an arrangement by which the supply of electrical current is terminated once the bimetallic strip 18 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 the heater 3, or until the supply of electrical current is terminated. The apparatus 1 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, the heater 3 may be restarted if the electrical current is reinstated, provided that the resistive contact between the elements 17, 19, 24 is sufficient to restart the process. However, because the temperature-sensitive element 17 may return to its original shape as it cools, the heating zone may restart from the first end 20 of the heater 3. To avoid this, the heater 3 may comprise an arrangement which prevents the temperature-sensitive element 17 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, the apparatus 1 may comprise a plurality of heaters 3 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 of elements 17, 19 may be made of any electrically conductive material, such as copper for example. The elements 17, 19 may be made of the same or different materials. Generally, the elements 17, 19 should be durable and not consumed during the operation of the heater 3. However, single use is also envisaged.
The mass of the smokeable material 5 which is heated by the heater 3 may be in the range of 0.2 to 1 g. The temperature to which the smokeable material 5 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 the smokeable material 5 is heated to volatilize components of the smokeable material 5 may be, for example, any temperature within the temperature range of 120° C. to 250° C., as previously described. The mass of the apparatus 1 as a whole may be in the range of 70 to 125 g, although a smaller mass is also possible. An example battery 2 has a capacity of 1000 to 3000 mAh and a voltage of 3.7V.
In some embodiments, the smokeable material 5 may be comprised in a cartridge which can be inserted into the heating chamber. For example, as shown in FIGS. 1 and 2, the cartridge may comprise a smokeable material rod 5 which can be introduced into the apparatus 1 by removal of the mouthpiece 6 and insertion against the buffer 16. The smokeable material cartridge fits within the heater 3 so that the circumferential surface of the smokeable material rod 5 faces the internal surface of the heater 3, such that the heater 3 is a close fit around the rod 5 to ensure efficient heat transfer. The cartridge 5 is generally not longer than the heater 3 and may be approximately equal to the length of the heater 3 so that the heater 3 can heat the smokeable material 5 along its entire length.
In some embodiments, the thermal insulation 11 may be provided as part of the smokeable material cartridge 5, located co-axially around the outside of the heater 3.
An advantage of the apparatus 1, and in particular the heater 3, is that there is no requirement for a dedicated control system to regulate the heating of the smokeable material 5, and/or to adjust the section of smokeable material that is being heated. Instead, once the disclosed apparatus is activated, a small section of the smokeable material 5 is heated and the area of heating migrates at a substantially constant rate from one end of the smokeable material 5 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 the heater 3.
A further advantage of this arrangement is that activating only a small portion of the heater 3 means that the energy required to heat the smokeable material 5 is reduced in comparison to that required to heat the full amount of smokeable material over the entire period of use of the apparatus 1.
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

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 to claim 1, wherein the heater is configured to trigger alteration of the shape of the temperature-sensitive element.

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

6. The apparatus according to claim 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 to claim 1, wherein the heater comprises an electrode comprising the temperature-sensitive element.

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

9. The apparatus according to claim 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 to claim 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 to claim 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 to claim 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 to claim 1, wherein the temperature-sensitive element comprises a bimetallic strip.

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

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