Patent Description:
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 heating devices 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.

<CIT>describes an inductive heating arrangement for use with a device for heating smokable material to volatilise at least one component of said smokable material. The inductive heating arrangement comprises a susceptor arrangement, at least a first inductor coil and a second inductor coil and a control circuit for controlling the first inductor coil and the second inductor coil. The first inductor coil is for generating a first varying magnetic field for heating a first section of the susceptor arrangement and the second inductor coil is for generating a second varying magnetic field for heating a second section of the susceptor arrangement. The control circuit is configured so that when one of the first and second coils is actively being driven to generate a varying magnetic field the other of the first and second inductor coils is inactive and the control circuit is configured so that the inactive inductor coil is prevented from carrying a current induced by the active inductor coil that is sufficient to cause significant heating of the susceptor arrangement.

<CIT> describes an inductive heating device for aerosol-generation which includes an induction coil having a magnetic axis. A wire material forming the induction coil has a cross-section comprising a main portion, the main portion having a longitudinal extension in a direction of the magnetic axis and a lateral extension perpendicular to the magnetic axis, which longitudinal extension is longer than the lateral extension of the main portion.

According to a first aspect of the present disclosure, there is provided an aerosol provision device, comprising:
an inductor coil configured to generate a varying magnetic field for heating a susceptor arrangement, wherein the inductor coil is helical and formed from litz wire having an elliptical cross section and comprising between about <NUM> and about <NUM> wire strands.

According to another aspect of the present disclosure, there is provided an aerosol provision device, comprising:.

According to a further aspect of the present disclosure, there is provided an aerosol provision device, comprising:
an inductor coil configured to generate the varying magnetic field for heating the susceptor arrangement, wherein the inductor coil is helical and formed from litz wire having a rectangular cross section and comprising between about <NUM> and about <NUM> wire strands.

As used herein, the term "aerosol generating material" includes materials that provide volatilised components upon heating, typically in the form of an aerosol. Aerosol generating 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. Aerosol generating material also may include other, non-tobacco, products, which, depending on the product, may or may not contain nicotine. Aerosol generating material may for example be in the form of a solid, a liquid, a gel, a wax or the like. Aerosol generating material may for example also be a combination or a blend of materials. Aerosol generating material may also be known as "smokable material".

Apparatus is known that heats aerosol generating material to volatilise at least one component of the aerosol generating material, typically to form an aerosol which can be inhaled, without burning or combusting the aerosol generating material. Such apparatus is sometimes described as an "aerosol generating device", an "aerosol provision device", a "heat-not-burn device", a "tobacco heating product device" or a "tobacco heating device" or similar. Similarly, there are also so-called e-cigarette devices, which typically vaporise an aerosol generating material in the form of a liquid, which may or may not contain nicotine. The aerosol generating material may be in the form of or be provided as part of a rod, cartridge or cassette or the like which can be inserted into the apparatus. A heater for heating and volatilising the aerosol generating material may be provided as a "permanent" part of the apparatus.

An aerosol provision device can receive an article comprising aerosol generating material for heating. An "article" in this context is a component that includes or contains in use the aerosol generating material, which is heated to volatilise the aerosol generating material, and optionally other components in use. A user may insert the article into the aerosol provision device before it is heated to produce an aerosol, which the user subsequently inhales. The article may be, for example, of a predetermined or specific size that is configured to be placed within a heating chamber of the device which is sized to receive the article.

A first aspect of the present disclosure defines at least one inductor coil which is configured to generate a varying magnetic field for penetrating and heating a susceptor. As will be discussed in more detail herein, a susceptor (also known as a susceptor arrangement) is an electrically conducting object, which is heatable by the varying magnetic fields. An article comprising aerosol generating material can be received within the susceptor, or be arranged near to, or in contact with the susceptor. Once heated, the susceptor transfers heat to the aerosol generating material, which releases aerosol. In one example, the susceptor defines a receptacle and the susceptor receives the aerosol generating material.

In the first aspect, the inductor coil is helical and is formed from litz wire having an elliptical cross section which comprises a plurality of wire strands. A litz wire is a wire comprising a plurality of wire strands which is used to carry alternating current. Litz wire is used to reduce skin effect losses in a conductor, and comprises a plurality of individually insulated wires which are twisted or woven together. The result of this winding is to equalize the proportion of the overall length over which each strand is at the outside of the conductor. This has the effect of distributing the current equally among the wire strands, reducing the resistance in the wire. In some examples the litz wire comprises several bundles of wire strands, where the wire strands in each bundle are twisted together. The bundles of wires are then twisted or woven together in a similar way.

In the present disclosure, the litz wire of the inductor coil has between about <NUM> and about <NUM> wire strands. It has been found that an inductor coil formed with litz wire having an elliptical cross section and this many wire strands is suitable for heating a susceptor used in an aerosol provision device. It also provides a good balance between performance and cost.

Preferably, the litz wire of the inductor coil has between about <NUM> and about <NUM> wire strands. The litz wire may comprise between about <NUM> and about <NUM> wire strands, or between about <NUM> and about <NUM> wire strands.

In one example, the litz wire of the inductor coil has about <NUM> wire strands. Such a litz wire is particularly effective for heating a susceptor used in an aerosol provision device.

In another example, the litz wire of the inductor coil has between about <NUM> and about <NUM> wire strands, such as between about <NUM> and about <NUM> wire strands, or between about <NUM> and about <NUM> wire strands. In one example, the litz wire of the inductor coil has about <NUM> wire strands.

The litz wire may comprise at least four bundles of wire strands. Preferably, the litz wire comprises five bundles. As briefly mentioned above, each bundle comprises a plurality of wire strands and the wire strands in each bundle are twisted together. The bundles of wires can be twisted/woven together in a similar way. The wire strands in all of the bundles add up to the total number of wire strands in the litz wire. There may be the same number of wire strands in each bundle. When the wire strands are bundled together in the litz wire, and then further woven and twisted in bundles, the proportion of time that each wire spends at the edge of the bundle may be more even.

Each of the wire strands within the litz wire has a diameter. For example, the wire strands may have a diameter of between about <NUM> and about <NUM>. In some examples, the diameter is between <NUM> AWG (<NUM>) and <NUM> AWG (<NUM>), where AWG is the American Wire Gauge. In another example, the wire strands have a diameter of between <NUM> AWG (<NUM>) and <NUM> AWG (<NUM>). In another example, the wire strands have a diameter of between <NUM> AWG (<NUM>) and <NUM> AWG (<NUM>).

Preferably, the wire strands have a diameter of <NUM> AWG (<NUM>), such as about <NUM>. It has been found that a litz wire with the above specified number of wire strands and these dimensions provide a good balance between effective heating, lower cost, low resistance and ensuring that the aerosol provision device is compact and lightweight.

The litz wire may have a length of between about <NUM> and about <NUM>. For example, the litz wire may have a length between about <NUM> and about <NUM>, such as between about <NUM> and about <NUM>. Alternatively the litz wire may have a length of between about <NUM> and about <NUM>, such as between about <NUM> and about <NUM>. The length of the litz wire is the length when the coil is unravelled. In a particular arrangement, the litz wire has a length of about <NUM>, or about <NUM>. It has been found that these lengths are suitable for providing effective heating of the susceptor.

The inductor coil may have a length of between about <NUM> and about <NUM>. The length is measured along the axis of the helix formed by the coil. For example, the length may be between about <NUM> and about <NUM>, or between about <NUM> and about <NUM>. Preferably the inductor coil has a length of about <NUM> or about <NUM>.

The inductor coil may have between about <NUM> and <NUM> turns. A turn is one complete rotation about an axis. For example, the inductor coil may have between about <NUM> and <NUM> turns, such as <NUM> turns, or between about <NUM> and <NUM> turns, such as <NUM> turns. Inductor coils with these many turns can provide an effective magnetic field for heating the susceptor.

The inductor coil may comprise a litz wire wound (helically) with a particular pitch. The pitch is the length of the inductor coil (measured along the longitudinal axis of the device/susceptor) over one complete winding. A shorter pitch can induce a stronger magnetic field. Conversely, a longer pitch can induce a weaker magnetic field.

In one arrangement, the pitch is between about <NUM> and about <NUM>, or between about <NUM> and about <NUM>. For example, the pitch may be between about <NUM> and about <NUM>. Preferably the pitch is about <NUM> or about <NUM>, such as about <NUM> or about <NUM>. It has been found that these particular pitches provide effective heating of the susceptor and hence the aerosol generating material.

A battery can power the inductor coils. The battery may have a voltage of between about <NUM>. 9V and <NUM>. 16V, and can supply a peak current of about 18Amps.

In one example, the inner diameter of the inductor coil is about <NUM>-<NUM>, and the outer diameter is about <NUM>-<NUM>. In a particular example, the inner diameter of the inductor coil is about <NUM>-<NUM>, and the outer diameter is about <NUM>-<NUM>. Preferably the inner diameter of the coil is about <NUM>, and the outer diameter is about <NUM>. The inner diameter of a helical inductor coil is any straight-line segment that passes through the center of the inductor coil (as viewed in cross section) and whose endpoints lie on the inner perimeter of the coil. The outer diameter of a helical inductor coil is any straight-line segment that passes through the center of the inductor coil (as viewed in cross section) and whose endpoints lie on the outer perimeter of the coil. These dimensions can provide effective heating of the susceptor arrangement while retaining a compact outer size.

The inductor coil may comprise gaps between successive turns and each gap may have a length of between about <NUM> and <NUM>, such as between about <NUM> and about <NUM>. Preferably the gap is about <NUM> or <NUM>, such as about <NUM> or <NUM>. These dimensions provide a magnetic field of a suitable strength for heating the susceptor. The gap length is measured in a direction parallel to the longitudinal axis of the device/susceptor/inductor coil. A gap is a portion where no wire of the coil is present (i.e. there is a space between successive turns).

The inductor coil may have a mass between about <NUM> and about <NUM>. In a particular arrangement, the inductor coil has a mass of between about <NUM> and <NUM>, such as <NUM> or between about <NUM> and about <NUM>, such as <NUM>.

As mentioned, the litz wire has an elliptical cross section. In a particular example, the litz wire has a circular cross section. The litz wire may therefore have a diameter of between about <NUM> and about <NUM> or between about <NUM> and about <NUM>. Preferably the litz wire has a diameter of about <NUM>.

In examples where the litz wire does not have a circular cross section, the major axis of the ellipse may be parallel to a longitudinal axis of the susceptor/coil. The major axis may have a length of between about <NUM> and about <NUM>. The minor axis has a length that is shorter than the length of the major axis. The minor axis may have a length of between about <NUM> and about <NUM>.

In some examples, in use, the inductor coil is configured to heat the susceptor to a temperature of between about <NUM> degrees Celsius and about <NUM> degrees Celsius, such as between about <NUM> degrees Celsius and about <NUM> degrees Celsius.

The inductor coil may be positioned away from an outer surface of the susceptor by a distance of between about <NUM> and about <NUM>. Accordingly, an inner surface of the inductor coil and the outer surface of the susceptor may be spaced apart by this distance. The distance may be a radial distance. It has been found that distances within this range represent a good balance between the susceptor being radially close to the inductor coil to allow efficient heating and being radially distant for improved insulation of the induction coil and insulating member.

In another example, the inductor coil may be positioned away from the outer surface of the susceptor by a distance of greater than about <NUM>.

In another example, the inductor coil may be positioned away from an outer surface of the susceptor by a distance of between about <NUM> and about <NUM>. In a further example, the inductor coil may be positioned away from an outer surface of the susceptor by a distance of between about <NUM> and about <NUM>, for example preferably by about <NUM>. In another example, the inductor coil may be positioned away from an outer surface of the susceptor by a distance greater than about <NUM>. In a further example the inductor coil may be positioned away from an outer surface of the susceptor by a distance of less than about <NUM>, or by less than about <NUM>. It has been found that these distances provide a balance between the susceptor being radially close to the inductor coil to allow efficient heating and being radially distant for improved insulation of the induction coil and insulating member.

In some examples, each of the plurality of wire strands comprises a bondable coating. A bondable coating is a coating which surrounds each wire strand, and which can be activated (such as via heating), so that the strands within the litz wire bond to one more neighbouring strands. The bondable coating allows the litz wire to be formed into the shape of an inductor coil on a support member, and after the bondable coating is activated, the inductor coil will retain its shape. The bondable coating therefore "sets" the shape of the inductor coil. In some examples, the bondable coating is the electrically insulating layer which surrounds the conductive core. However, the bondable coating and the insulation may also be separate layers, and the bondable coating surrounds the insulating layer. In an example, the conductive core of the litz wire comprises copper.

In a particular example, the aerosol provision device comprises the susceptor arrangement. In other examples, an article comprising aerosol generating material comprises the susceptor arrangement.

The susceptor arrangement may be hollow and/or substantially tubular to allow the aerosol generating material to be received within the susceptor, such that the susceptor surrounds the aerosol generating material.

Preferably, the device is a tobacco heating device, also known as a heat-not-burn device.

In a further aspect, the inductor coil is helical and is formed from litz wire having a rectangular cross section which comprises a plurality of wire strands. In this aspect, the litz wire of the inductor coil has between about <NUM> and about <NUM> wire strands. Again, it has been found that an inductor coil formed with litz wire having a rectangular cross section and this many wire strands is suitable for heating a susceptor used in an aerosol provision device. It also provides a good balance between performance and cost.

Preferably, the litz wire of the inductor coil has between about <NUM> and about <NUM> wire strands. Still more preferably, the litz wire comprises between about <NUM> and about <NUM> wire strands, or between about <NUM> and about <NUM> wire strands. Most preferably, the litz wire of the inductor coil has about <NUM> wire strands. Such a litz wire is particularly effective for heating a susceptor used in an aerosol provision device. The litz wire may comprise at least four bundles of wire strands.

The litz wire may comprise at least four bundles of wire strands. Preferably, the litz wire comprises five bundles. There may be the same number of wire strands in each bundle.

The inductor coil may have between about <NUM> and <NUM> turns. A turn is one complete rotation about an axis. For example, the inductor coil may have between about <NUM> and <NUM> turns, such as <NUM> turns, or between about <NUM> and <NUM> turns, such as <NUM> turns. Inductor coils with these many turns provide an effective magnetic field for heating the susceptor.

In one arrangement, the pitch is between about <NUM> and about <NUM>, or between about <NUM> and about <NUM>. For example, the pitch may be between about <NUM> and about <NUM>. Preferably the pitch is about <NUM> or about <NUM>. It has been found that these particular pitches provide effective heating of the susceptor and hence the aerosol generating material.

In one example, the inner diameter of the inductor coil is about <NUM>-<NUM>, and the outer diameter is about <NUM>-<NUM>. In a particular example, the inner diameter of the inductor coil is about <NUM>-<NUM>, and the outer diameter is about <NUM>-<NUM>. Preferably the inner diameter of the coil is about <NUM>, and the outer diameter is about <NUM>. These dimensions can provide effective heating of the susceptor arrangement while retaining a compact outer size.

The inductor coil may comprise gaps between successive turns and each gap may have a length of between about <NUM> and <NUM>. These dimensions provide a magnetic field of a suitable strength for heating the susceptor.

As mentioned, the litz wire in this example has a rectangular cross section. The rectangle may have two short sides and two long sides, where the dimensions of the sides of the rectangle define the area of the rectangular cross section. Other examples may have a generally square cross section, with four substantially equal sides. The cross-sectional area may be between about <NUM><NUM> and about <NUM><NUM>. In a preferred example, the cross-sectional area is between about <NUM><NUM> and about <NUM><NUM>, or between about <NUM><NUM> and about <NUM><NUM>. Preferably the cross-sectional area is between about <NUM><NUM> and about <NUM><NUM>.

In examples having a rectangular cross section with two short and two long sides, the short sides may have a dimension of between about <NUM> and about <NUM>, and the long sides may have a dimension of between about <NUM> and about <NUM>. Alternatively, the short sides may have a dimension of between about <NUM> and about <NUM>, and the long sides may have a dimension of between about <NUM> and about <NUM>. Preferably the short sides have a dimension of about <NUM> (±<NUM>) and the long sides have a dimension of about <NUM> (±<NUM>). In such an example, the cross-sectional area is about <NUM><NUM>.

Other features of the aerosol provision device and/or wire strands may be the same as in the first aspect.

<FIG> shows an example of an aerosol provision device <NUM> for generating aerosol from an aerosol generating medium/material. In broad outline, the device <NUM> may be used to heat a replaceable article <NUM> comprising the aerosol generating medium, to generate an aerosol or other inhalable medium which is inhaled by a user of the device <NUM>.

The device <NUM> comprises a housing <NUM> (in the form of an outer cover) which surrounds and houses various components of the device <NUM>. The device <NUM> has an opening <NUM> in one end, through which the article <NUM> may be inserted for heating by a heating assembly. In use, the article <NUM> may be fully or partially inserted into the heating assembly where it may be heated by one or more components of the heater assembly.

The device <NUM> of this example comprises a first end member <NUM> which comprises a lid <NUM> which is moveable relative to the first end member <NUM> to close the opening <NUM> when no article <NUM> is in place. In <FIG>, the lid <NUM> is shown in an open configuration, however the cap <NUM> may move into a closed configuration. For example, a user may cause the lid <NUM> to slide in the direction of arrow "A".

The device <NUM> may also include a user-operable control element <NUM>, such as a button or switch, which operates the device <NUM> when pressed. For example, a user may turn on the device <NUM> by operating the switch <NUM>.

The device <NUM> may also comprise an electrical component, such as a socket/port <NUM>, which can receive a cable to charge a battery of the device <NUM>. For example, the socket <NUM> may be a charging port, such as a USB charging port.

<FIG> depicts the device <NUM> of <FIG> with the outer cover <NUM> removed and without an article <NUM> present. The device <NUM> defines a longitudinal axis <NUM>.

As shown in <FIG>, the first end member <NUM> is arranged at one end of the device <NUM> and a second end member <NUM> is arranged at an opposite end of the device <NUM>. The first and second end members <NUM>, <NUM> together at least partially define end surfaces of the device <NUM>. For example, the bottom surface of the second end member <NUM> at least partially defines a bottom surface of the device <NUM>. Edges of the outer cover <NUM> may also define a portion of the end surfaces. In this example, the lid <NUM> also defines a portion of a top surface of the device <NUM>.

The end of the device closest to the opening <NUM> may be known as the proximal end (or mouth end) of the device <NUM> because, in use, it is closest to the mouth of the user. In use, a user inserts an article <NUM> into the opening <NUM>, operates the user control <NUM> to begin heating the aerosol generating material and draws on the aerosol generated in the device. This causes the aerosol to flow through the device <NUM> along a flow path towards the proximal end of the device <NUM>.

The other end of the device furthest away from the opening <NUM> may be known as the distal end of the device <NUM> because, in use, it is the end furthest away from the mouth of the user. As a user draws on the aerosol generated in the device, the aerosol flows away from the distal end of the device <NUM>.

The device <NUM> further comprises a power source <NUM>. The power source <NUM> may be, for example, a battery, such as a rechargeable battery or a non-rechargeable battery. Examples of suitable batteries include, for example, a lithium battery (such as a lithium-ion battery), a nickel battery (such as a nickel-cadmium battery), and an alkaline battery. The battery is electrically coupled to the heating assembly to supply electrical power when required and under control of a controller (not shown) to heat the aerosol generating material. In this example, the battery is connected to a central support <NUM> which holds the battery <NUM> in place.

The device further comprises at least one electronics module <NUM>. The electronics module <NUM> may comprise, for example, a printed circuit board (PCB). The PCB <NUM> may support at least one controller, such as a processor, and memory. The PCB <NUM> may also comprise one or more electrical tracks to electrically connect together various electronic components of the device <NUM>. For example, the battery terminals may be electrically connected to the PCB <NUM> so that power can be distributed throughout the device <NUM>. The socket <NUM> may also be electrically coupled to the battery via the electrical tracks.

In the example device <NUM>, the heating assembly is an inductive heating assembly and comprises various components to heat the aerosol generating material of the article <NUM> via an inductive heating process. Induction heating is a process of heating an electrically conducting object (such as a susceptor) by electromagnetic induction. An induction heating assembly may comprise an inductive element, for example, one or more inductor coils, and a device for passing a varying electric current, such as an alternating electric current, through the inductive element. The varying electric current in the inductive element produces a varying magnetic field. The varying magnetic field penetrates a susceptor suitably positioned with respect to the inductive element, and generates eddy currents inside the susceptor. The susceptor has electrical resistance to the eddy currents, and hence the flow of the eddy currents against this resistance causes the susceptor to be heated by Joule heating. In cases where the susceptor comprises ferromagnetic material such as iron, nickel or cobalt, heat may also be generated by magnetic hysteresis losses in the susceptor, i.e. by the varying orientation of magnetic dipoles in the magnetic material as a result of their alignment with the varying magnetic field. In inductive heating, as compared to heating by conduction for example, heat is generated inside the susceptor, allowing for rapid heating. Further, there need not be any physical contact between the inductive heater and the susceptor, allowing for enhanced freedom in construction and application.

The induction heating assembly of the example device <NUM> comprises a susceptor arrangement <NUM> (herein referred to as "a susceptor"), a first inductor coil <NUM> and a second inductor coil <NUM>. The first and second inductor coils <NUM>, <NUM> are made from an electrically conducting material. In this example, the first and second inductor coils <NUM>, <NUM> are made from Litz wire/cable which is wound in a helical fashion to provide helical inductor coils <NUM>, <NUM>. Litz wire comprises a plurality of individual wires which are individually insulated and are twisted together to form a single wire. Litz wires are designed to reduce the skin effect losses in a conductor. In the example device <NUM>, the first and second inductor coils <NUM>, <NUM> are made from copper Litz wire which has a rectangular cross section. In other examples the Litz wire can have other shape cross sections, such as elliptical.

The first inductor coil <NUM> is configured to generate a first varying magnetic field for heating a first section of the susceptor <NUM> and the second inductor coil <NUM> is configured to generate a second varying magnetic field for heating a second section of the susceptor <NUM>. In this example, the first inductor coil <NUM> is adjacent to the second inductor coil <NUM> in a direction along the longitudinal axis <NUM> of the device <NUM> (that is, the first and second inductor coils <NUM>, <NUM> to not overlap). The susceptor arrangement <NUM> may comprise a single susceptor, or two or more separate susceptors. Ends <NUM> of the first and second inductor coils <NUM>, <NUM> can be connected to the PCB <NUM>.

It will be appreciated that the first and second inductor coils <NUM>, <NUM>, in some examples, may have at least one characteristic different from each other. For example, the first inductor coil <NUM> may have at least one characteristic different from the second inductor coil <NUM>. More specifically, in one example, the first inductor coil <NUM> may have a different value of inductance than the second inductor coil <NUM>. In <FIG>, the first and second inductor coils <NUM>, <NUM> are of different lengths such that the first inductor coil <NUM> is wound over a smaller section of the susceptor <NUM> than the second inductor coil <NUM>. Thus, the first inductor coil <NUM> may comprise a different number of turns than the second inductor coil <NUM> (assuming that the spacing between individual turns is substantially the same). In yet another example, the first inductor coil <NUM> may be made from a different material to the second inductor coil <NUM>. In some examples, the first and second inductor coils <NUM>, <NUM> may be substantially identical.

In this example, the first inductor coil <NUM> and the second inductor coil <NUM> are wound in opposite directions. This can be useful when the inductor coils are active at different times. For example, initially, the first inductor coil <NUM> may be operating to heat a first section/portion of the article <NUM>, and at a later time, the second inductor coil <NUM> may be operating to heat a second section/portion of the article <NUM>. Winding the coils in opposite directions helps reduce the current induced in the inactive coil when used in conjunction with a particular type of control circuit. In <FIG>, the first inductor coil <NUM> is a right-hand helix and the second inductor coil <NUM> is a left-hand helix. However, in another embodiment, the inductor coils <NUM>, <NUM> may be wound in the same direction, or the first inductor coil <NUM> may be a left-hand helix and the second inductor coil <NUM> may be a right-hand helix.

The susceptor <NUM> of this example is hollow and therefore defines a receptacle within which aerosol generating material is received. For example, the article <NUM> can be inserted into the susceptor <NUM>. In this example the susceptor <NUM> is tubular, with a circular cross section.

The device <NUM> of <FIG> further comprises an insulating member <NUM> which may be generally tubular and at least partially surround the susceptor <NUM>. The insulating member <NUM> may be constructed from any insulating material, such as plastic for example. In this particular example, the insulating member is constructed from polyether ether ketone (PEEK). The insulating member <NUM> may help insulate the various components of the device <NUM> from the heat generated in the susceptor <NUM>.

The insulating member <NUM> can also fully or partially support the first and second inductor coils <NUM>, <NUM>. For example, as shown in <FIG>, the first and second inductor coils <NUM>, <NUM> are positioned around the insulating member <NUM> and are in contact with a radially outward surface of the insulating member <NUM>. In some examples the insulating member <NUM> does not abut the first and second inductor coils <NUM>, <NUM>. For example, a small gap may be present between the outer surface of the insulating member <NUM> and the inner surface of the first and second inductor coils <NUM>, <NUM>.

In a specific example, the susceptor <NUM>, the insulating member <NUM>, and the first and second inductor coils <NUM>, <NUM> are coaxial around a central longitudinal axis of the susceptor <NUM>.

<FIG> shows a side view of device <NUM> in partial cross-section. The outer cover <NUM> is present in this example. The rectangular cross-sectional shape of the first and second inductor coils <NUM>, <NUM> is more clearly visible.

The device <NUM> further comprises a support <NUM> which engages one end of the susceptor <NUM> to hold the susceptor <NUM> in place. The support <NUM> is connected to the second end member <NUM>.

The device may also comprise a second printed circuit board <NUM> associated within the control element <NUM>.

The device <NUM> further comprises a second lid/cap <NUM> and a spring <NUM>, arranged towards the distal end of the device <NUM>. The spring <NUM> allows the second lid <NUM> to be opened, to provide access to the susceptor <NUM>. A user may open the second lid <NUM> to clean the susceptor <NUM> and/or the support <NUM>.

The device <NUM> further comprises an expansion chamber <NUM> which extends away from a proximal end of the susceptor <NUM> towards the opening <NUM> of the device. Located at least partially within the expansion chamber <NUM> is a retention clip <NUM> to abut and hold the article <NUM> when received within the device <NUM>. The expansion chamber <NUM> is connected to the end member <NUM>.

<FIG> is an exploded view of the device <NUM> of <FIG>, with the outer cover <NUM> omitted.

<FIG> depicts a cross section of a portion of the device <NUM> of <FIG>. <FIG> depicts a close-up of a region of <FIG> show the article <NUM> received within the susceptor <NUM>, where the article <NUM> is dimensioned so that the outer surface of the article <NUM> abuts the inner surface of the susceptor <NUM>. This ensures that the heating is most efficient. The article <NUM> of this example comprises aerosol generating material 110a. The aerosol generating material 110a is positioned within the susceptor <NUM>. The article <NUM> may also comprise other components such as a filter, wrapping materials and/or a cooling structure.

<FIG> shows that the outer surface of the susceptor <NUM> is spaced apart from the inner surface of the inductor coils <NUM>, <NUM> by a distance <NUM>, measured in a direction perpendicular to a longitudinal axis <NUM> of the susceptor <NUM>. In one particular example, the distance <NUM> is about <NUM> to <NUM>, about <NUM>-<NUM>, or about <NUM>.

<FIG> further shows that the outer surface of the insulating member <NUM> is spaced apart from the inner surface of the inductor coils <NUM>, <NUM> by a distance <NUM>, measured in a direction perpendicular to a longitudinal axis <NUM> of the susceptor <NUM>. In one particular example, the distance <NUM> is about <NUM>. In another example, the distance <NUM> is substantially <NUM>, such that the inductor coils <NUM>, <NUM> abut and touch the insulating member <NUM>.

In one example, the susceptor <NUM> has a wall thickness <NUM> of about <NUM> to <NUM>, or about <NUM>.

In one example, the susceptor <NUM> has a length of about <NUM> to <NUM>, about <NUM>-<NUM>, or about <NUM>.

In one example, the insulating member <NUM> has a wall thickness <NUM> of about <NUM> to <NUM>, <NUM> to <NUM>, or about <NUM>.

<FIG> depicts the heating assembly of the device <NUM>. As briefly mentioned above, the heating assembly comprises a first inductor coil <NUM> and a second inductor coil <NUM> arranged adjacent to each other, in the direction along the axis <NUM> (which is also parallel to the longitudinal axis <NUM> of the device <NUM>). In use, the first inductor coil <NUM> is operated initially. This causes a first section of the susceptor <NUM> to heat up (i.e. the section of the susceptor <NUM> surrounded by the first inductor coil <NUM>), which in turn heats a first portion of the aerosol generating material. At a later time, the first inductor coil <NUM> may be switched off, and the second inductor coil <NUM> may be operated. This causes a second section of the susceptor <NUM> to heat up (i.e. the section of the susceptor <NUM> surrounded by the second inductor coil <NUM>), which in turn heats a second portion of the aerosol generating material. The second inductor coil <NUM> may be switched on while the first inductor coil <NUM> is being operated, and the first inductor coil <NUM> may switch off while the second inductor coil <NUM> continues to operate. Alternatively, the first inductor coil <NUM> may be switched off before the second inductor coil <NUM> is switched on. A controller can control when each inductor coil is operated/energised.

In some examples, the length <NUM> of the first inductor coil <NUM> is shorter than the length <NUM> of the second inductor coil <NUM>. The length of each inductor coil is measured in a direction parallel to an axis of the inductor coils <NUM>, <NUM>. The first, shorter inductor coil <NUM> may be arranged closer to the mouth end (proximal end) of the device <NUM> than the second inductor coil <NUM>. When the aerosol generating material is heated, aerosol is released. When a user inhales, the aerosol is drawn towards the mouth end of the device <NUM>, in the direction of arrow <NUM>. The aerosol exits the device <NUM> via the opening/mouthpiece <NUM>, and is inhaled by the user. The first inductor coil <NUM> is arranged closer to the opening <NUM> than the second inductor coil <NUM>.

In this example, the first inductor coil <NUM> has a length <NUM> of about <NUM>, and the second inductor coil <NUM> has a length <NUM> of about <NUM>. A first wire, which is helically wound to form the first inductor coil <NUM>, has an unwound length of about <NUM>. A second wire, which is helically wound to form the second inductor coil <NUM>, has an unwound length of about <NUM>.

Each inductor coil <NUM>, <NUM> is formed from litz wire comprising a plurality of wire strands. For example, there may be between about <NUM> and about <NUM> wire strands in each litz wire. In the present example, there are about <NUM> wire strands in each litz wire. In some examples, the wire strands are grouped into two or more bundles, where each bundle comprises a number of wire strands such that the wire strands in all bundles add up to the total number of wire strands. In the present example there are <NUM> bundles of <NUM> wire strands.

Each of the wire strands have a diameter. For example, the diameter may be between about <NUM> and about <NUM>. In some examples, the diameter is between <NUM> AWG (<NUM>) and <NUM> AWG (<NUM>), where AWG is the American Wire Gauge. In this example, each of the wire strands have a diameter of <NUM> AWG (<NUM>).

As shown in <FIG>, the litz wire of the first inductor coil <NUM> is wrapped around the axis <NUM> about <NUM> times, and the litz wire of the second inductor coil <NUM> is wrapped around the axis <NUM> about <NUM> times. The litz wires do not form a whole number of turns because some ends of the litz wire are bent away from the surface of the insulating member <NUM> before a full turn is completed.

<FIG> shows a close up of the first inductor coil <NUM>. <FIG> shows a close up of the second inductor coil <NUM>. In this example, the first inductor coil <NUM> and the second inductor coil <NUM> have different pitches. The first inductor coil <NUM> has a first pitch <NUM>, and the second inductor coil has a second pitch <NUM>. The pitch is the length of the inductor coil (measured along the longitudinal axis <NUM> of the device or along the longitudinal axis <NUM> of the susceptor) over one complete winding. In this example, the first pitch is smaller than the second pitch, more specifically the first pitch <NUM> is about <NUM>, and the second pitch <NUM> is about <NUM>. In other example, the pitches are the same for each inductor coil, or the second pitch is smaller than the first pitch.

<FIG> depicts the first inductor coil <NUM> with about <NUM> turns, where one turn is one complete rotation around the axis <NUM>. Between each successive turn, there is a gap <NUM>. In this example, the length of the gap <NUM> is about <NUM>. Similarly, <FIG> depicts the second inductor coil <NUM> with about <NUM> turns. Between each successive turn, there is a gap <NUM>. In this example, the length of the gap <NUM> is about <NUM>. The gap size is equal to the difference between the pitch and the dimension of the litz wire along the inductor coil/axis <NUM>.

In this example, the first inductor coil <NUM> has a mass of about <NUM>, and the second inductor coil <NUM> has a mass of about <NUM>.

<FIG> is a diagrammatic representation of a cross section through the litz wire forming either of the first and second inductor coils <NUM>, <NUM>. As shown, the litz wire has a rectangular cross section (the individual wires forming the litz wire are not shown for clarity). The shorter side of the cross-section has a dimension <NUM> and the longer side of the cross-section has a dimension <NUM>. In this example, the short side has a dimension <NUM> of about <NUM>, and the long side has a dimension <NUM> of about <NUM>. The total cross-sectional area is therefore about <NUM><NUM>. In the arrangement of <FIG> and <FIG>, the long side is arranged perpendicular to the longitudinal axis <NUM> of the susceptor <NUM> to achieve the desired magnetic field strength.

<FIG> is a diagrammatic representation of a top down view of either of the inductor coils <NUM>, <NUM>. In this example the inductor coil <NUM>, <NUM> is arranged coaxially with the longitudinal axis <NUM> of the susceptor <NUM> (although the susceptor <NUM> is not depicted for clarity).

<FIG> shows the inductor coil <NUM>, <NUM> with outer diameter <NUM> and an inner diameter <NUM>. The outer diameter <NUM> may be between about <NUM> and about <NUM> and the inner diameter <NUM> may be between about <NUM> and about <NUM>. In this particular example, the inner diameter <NUM> is about <NUM> in length, and the outer diameter <NUM> is about <NUM> in length.

<FIG> is another diagrammatic representation of a cross section of the heating assembly. <FIG> depicts the outer perimeter/surface of the inductor coils <NUM>, <NUM> being positioned away from the susceptor <NUM> by a distance <NUM>. Accordingly, the first and second inductor coils have substantially the same external diameter <NUM>. <FIG> also depicts the internal diameter <NUM> of the first and second inductor coils <NUM>, <NUM> as being substantially the same.

The "outer perimeter" of the inductor coils <NUM>, <NUM> is the edge of the inductor coil that is positioned furthest away from the outer surface 132a of the susceptor <NUM>, in a direction perpendicular to the longitudinal axis <NUM>.

As shown, the inner surfaces of the inductor coils <NUM>, <NUM> are positioned away from the outer surface 132a of the susceptor <NUM> by a distance <NUM>. The distance may be between about <NUM> and about <NUM>, such as about <NUM>.

<FIG> depicts another heating assembly for use in the device <NUM>. In this example, the rectangular cross section litz wires which form the inductor coils have been replaced with inductor coils comprising litz wire with a circular cross section. Other features of the device <NUM> are substantially the same.

The heating assembly comprises a first inductor coil <NUM> and a second inductor coil <NUM> arranged adjacent to each other, in the direction along a longitudinal axis <NUM> defined by the susceptor <NUM> (which is also parallel to the longitudinal axis <NUM> of the device <NUM>). In use, the first inductor coil <NUM> is operated initially. This causes a first section of the susceptor <NUM> to heat up (i.e. the section of the susceptor <NUM> surrounded by the first inductor coil <NUM>), which in turn heats a first portion of the aerosol generating material. At a later time, the first inductor coil <NUM> may be switched off, and the second inductor coil <NUM> may be operated. This causes a second section of the susceptor <NUM> to heat up (i.e. the section of the susceptor <NUM> surrounded by the second inductor coil <NUM>), which in turn heats a second portion of the aerosol generating material. The second inductor coil <NUM> may be switched on while the first inductor coil <NUM> is being operated, and the first inductor coil <NUM> may switch off while the second inductor coil <NUM> continues to operate. Alternatively, the first inductor coil <NUM> may be switched off before the second inductor coil <NUM> is switched on. A controller can control when each inductor coil is operated/energised.

In some examples, the length <NUM> of the first inductor coil <NUM> is shorter than the length <NUM> of the second inductor coil <NUM>. The length of each inductor coil is measured in a direction parallel to an axis defined by the inductor coils <NUM>, <NUM>. The first, shorter inductor coil <NUM> may be arranged closer to the mouth end (proximal end) of the device <NUM> than the second inductor coil <NUM>. When the aerosol generating material is heated, aerosol is released. When a user inhales, the aerosol is drawn towards the mouth end of the device <NUM>, in the direction of arrow <NUM>. The aerosol exits the device <NUM> via the opening/mouthpiece <NUM>, and is inhaled by the user. The first inductor coil <NUM> is arranged closer to the opening <NUM> than the second inductor coil <NUM>.

As shown in <FIG>, the litz wire of the first inductor coil <NUM> is wrapped around the axis 158about <NUM> times, and the litz wire of the second inductor coil <NUM> is wrapped around the axis <NUM> about <NUM> times. The litz wires do not form a whole number of turns because some ends of the litz wire are bent away from the surface of the insulating member <NUM> before a full turn is completed.

<FIG> depicts the first inductor coil <NUM> with about <NUM> turns, where one turn is one complete rotation around the axis <NUM>. Between each successive turn, there is a gap <NUM>. In this example, the length of the gap <NUM> is about <NUM>. Similarly, <FIG> depicts the second inductor coil <NUM> with about <NUM> turns. Between each successive turn, there is a gap <NUM>. In this example, the length of the gap <NUM> is about <NUM>. The gap size is equal to the difference between the pitch and the diameter of the litz wire. Thus, in this example, the litz wire has a diameter of about <NUM>.

<FIG> is a diagrammatic representation of a cross section through the litz wire forming either of the first and second inductor coils <NUM>, <NUM>. As shown, the litz wire has a circular cross section (the individual wires forming the litz wire are not shown for clarity). The litz wire has a diameter <NUM>, which may be between about <NUM> and about <NUM>. In this example, the diameter is about <NUM>.

Claim 1:
An aerosol provision device (<NUM>), comprising:
an inductor coil (<NUM>, <NUM>) configured to generate a varying magnetic field for heating a susceptor arrangement (<NUM>), characterised in that the inductor coil (<NUM>, <NUM>) is helical and formed from litz wire having an elliptical or rectangular cross section and comprising between <NUM> and <NUM> wire strands.