Induction heating assembly for vapor generating device and vapor generating system

Abstract

The invention provides an induction heating assembly for a steam generation device and a steam generation system. The induction heating assembly includes: an outer body; an induction coil disposed inside the outer body; a heating compartment defined inside the induction coil and arranged to receive, in use, a body comprising a vaporizable substance and an inductively heatable susceptor, where the outer body and the induction coil are spaced apart from each other and define a vent arranged to allow a flow of air into the heating compartment, the air is heated before entering the body in use.

Description

[0001] This application is a divisional application of an application filed on December 20, 2018, with application number 201880084385.0 (international application number PCT / EP2018 / 086125), and invention name “Induction heating component for a steam generating device”. Technical Field

[0002] The present invention relates to an induction heating assembly for a steam generating device. Background Art

[0003] Devices that heat substances rather than burn them to produce vapor for inhalation have become popular with consumers in recent years.

[0004] Such a device can use one of a number of different approaches to provide heat to the substance. One such approach is to simply provide a heating element, supply power thereto so that the element heats, which in turn heats the substance to produce vapor.

[0005] One way to achieve this type of steam generation is to provide a steam-generating device that utilizes induction heating. In such a device, the device is equipped with an induction coil (hereinafter also referred to as an inductor or induction heating device), and a susceptor is provided to the steam-generating substance. When a user activates the device, electrical energy is supplied to the inductor, which in turn generates an electromagnetic (EM) field. The susceptor couples with the field and generates heat, which is transferred to the substance, generating steam when the substance is heated.

[0006] Using induction heating to generate steam has the potential to provide controlled heating, and therefore controlled steam generation. However, in practice, this approach can lead to unintended generation of inappropriate temperatures within the steam generating device. This can waste electricity, making operation expensive, and carries the risk of damaging components or rendering the steam generating device ineffective, inconveniencing users who desire a simple, reliable device.

[0007] This problem has previously been addressed by monitoring the temperature in the device. However, some monitored temperatures have been found to be unreliable, and providing temperature monitoring adds component count and uses additional power, even if the overall power usage is more efficient due to temperature monitoring.

[0008] The present invention seeks to alleviate at least some of the above problems. Summary of the Invention

[0009] According to a first aspect, there is provided an induction heating assembly for a steam generating device, the heating assembly comprising: an outer body; an induction coil arranged inside the outer body; a heating compartment defined inside the induction coil and arranged to receive a body comprising a vaporizable substance and an inductively heatable susceptor when in use, wherein a gap between the outer body and the induction coil defines an air vent arranged to allow air to flow around the induction coil and to the heating compartment.

[0010] The susceptor may include, but is not limited to, one or more of aluminum, iron, nickel, stainless steel, and alloys thereof (e.g., nickel-chromium alloy). By applying an electromagnetic field near the susceptor, the susceptor may generate heat due to eddy currents and hysteresis losses, thereby converting electromagnetic energy into thermal energy.

[0011] We have discovered that allowing air to flow around the induction coil and to the longitudinal ends of the heating compartment allows heat to be transferred to the air before it enters the heating compartment. This cools the induction coil, allowing it to operate more efficiently and stabilize its operation, and reduces the amount of heating that needs to be applied directly to the vaporizable substance, since the air entering the heating compartment also heats the vaporizable substance (or at least reduces the cooling effect it has). This reduces the amount of energy required to heat the vaporizable substance. A further benefit is that the transfer of heat to the external body is limited, which prevents the external body from heating up and, therefore, the external surfaces from heating up. When the body is located in the heating compartment, these benefits can be achieved without increasing the distance between the induction coil and the inductively heatable susceptor. This means that the energy transferred from the induction coil to the susceptor is not reduced, allowing the energy to be transferred as efficiently as possible, and therefore the heat to be generated as efficiently as possible.

[0012] The induction coil may be a cylindrical induction coil. In this case, the induction coil may be arranged radially inwardly of the outer body, wherein the heating compartment defines the radially inner portion of the induction coil, and wherein the spacing defining the vent between the outer body and the induction coil may be a radial spacing. As an alternative to the cylindrical induction coil, the induction coil may be a helical flat induction coil.

[0013] The vent can be shaped to direct air flow around the induction coil and then into the heating compartment. This provides insulation to the outer body by separating the induction coil from the outer body through the air in the vent, while also heating the air before it enters the heating compartment, thereby reducing the amount of heat required to be applied to the heating compartment. This reduces power usage while also protecting the user from exposure to heat.

[0014] The heating compartment may be adjacent to the induction coil. Although the induction coil may be embedded in a wall of the heating compartment, because there are no other elements between the wall in which the induction coil is embedded and the cavity of the heating compartment, and because the wall partially defines the heating compartment, this is intended to be within the meaning of the term "adjacent".

[0015] As described above, the body includes a vaporizable substance and an inductively heatable susceptor. The body may contain both the vaporizable substance and the inductively heatable susceptor. In this configuration, induction heating occurs only within the body. Therefore, when the body is within the heating compartment, heat generated within the heating compartment is not generated externally to the body. In other words, the heating compartment can be arranged to provide heat only within the body when the body is within the heating compartment. This is because, in this configuration, heat generated by the inductively heatable susceptor when current passes through the induction coil is generated only within the body.

[0016] Heat can be generated outside the heating compartment. Typically, the heat generated outside the heating compartment is generated by an induction coil. This heat can provide additional heating to any vaporizable substance in the heating compartment.

[0017] The vent can be arranged to allow air to flow around the induction coil and to any part of the heating compartment. Typically, however, the vent is arranged to allow air to flow around the induction coil and to the axial ends of the heating compartment. This avoids the vent interfering with the induction coil in any way and allows the maximum amount of heat to be transferred to the air in the vent, as its path to the axial ends of the heating compartment will be longer than the vent's path through any other part of the heating compartment.

[0018] In a first aspect, when the body is positioned within the heating compartment, the body may abut the side of the heating compartment. Preferably, when the body is positioned within the heating compartment, an airflow path exists only through the body within the heating compartment. In this case, there may be no airflow path between the induction coil and the body from the inlet to the outlet of the heating compartment. This limits airflow around the body between the body and the side of the heating compartment. This allows the susceptor to be positioned as close as possible to the induction coil and increases airflow through the body, rather than around it.

[0019] The vents may be formed in any suitable manner. Typically, the induction heating assembly further comprises one or more spacers disposed between the outer body and the induction coil to define two or more layers of vents. This allows for more efficient heat transfer from the induction coil to the air and thereby limits heat transfer to the outer body, as the multiple layers provide increased surface area relative to the volume of air available for heat transfer.

[0020] Alternatively or additionally, the induction heating assembly may further include ribs that support the outer body, the induction coil, and optional separators in mechanical connection and divide the vent into a plurality of sections. This is intended to mean that there may be ribs that provide mechanical connection between the outer body, the induction coil, and the separators (if they are present), that support these components and divide the vent into a plurality of sections. This provides suitable structural support for a plurality of different components while allowing a large amount of surface area for air to pass through, thereby improving the heat transfer effect. When the induction coil is a cylindrical induction coil, the sections may be annular sections.

[0021] Having multiple layers of vents provides a variety of options for how air flows from the vent inlet through the vents to the heating compartment. Typically, the vents in these layers are arranged to provide an airflow path that passes through multiple vent layers, from one vent layer to another. This allows the airflow path to be lengthened by passing through multiple layers, thereby providing a longer length over which heat can be transferred to the air passing through the vents. This also makes heat transfer more efficient because the air in one layer is warmed by the air in the inner layer. In this arrangement, the air path can preferably pass along the length of the heating compartment in one layer and pass along the length of the heating compartment in the next layer, in the opposite direction.

[0022] In an alternative arrangement of vents, the vents of the layers can be arranged to provide an airflow path through at least two vent layers by being separated between each respective vent layer. This is also a means of providing more efficient heat transfer by allowing the air in multiple layers to be warmed simultaneously. Of course, the multiple layers or layers between which the airflow paths are separated can be radially adjacent (i.e., concentric) layers.

[0023] Typically, the induction heating assembly may further comprise structures in the vent, the structures being arranged to define one or more airflow paths. This provides increased surface area for air to pass through, allowing heat transfer to occur.

[0024] The air flow may follow any suitable path. Typically, the one or more airflow paths are arranged in one or more of the following: a spiral around the induction coil; a zigzag in the longitudinal direction of the coil; and a zigzag in the transverse direction of the coil. This maximizes the length of each airflow path, thereby allowing heat to be transferred more efficiently from the induction coil, because the air takes longer to pass along the corresponding airflow path, thereby allowing more heat to be absorbed. When the induction coil is a cylindrical induction coil, the spiral may be a spiral that rotates around the circumference of the induction coil, the zigzag in the longitudinal direction of the coil may be in the axial direction of the coil, and the zigzag in the transverse direction of the coil may be in the circumferential direction of the coil.

[0025] The one or more airflow paths may cover any amount of the induction coil to allow heat to be transferred from the induction coil. Typically, the airflow paths cover greater than 50%, preferably 50%-90%, and more preferably 50%-80% of the outer surface of the induction coil. We have found that this provides an appropriate amount of surface area over which heat transfer can occur while maintaining structural rigidity without unduly complicating manufacturing.

[0026] The induction heating assembly may further include an electromagnetic shield positioned: between the coil and the innermost vent; between concentric vents; substantially around the circumference of the outermost vent; or as a portion of the wall of the vent. The EM shield limits the amount of EM radiation that passes through the assembly. By positioning the EM shield adjacent to the vent (while still surrounding it or not), as is the case here, heat can also be transferred from the EM shield to the air if the EM shield is heated above the temperature of the air in the vent.

[0027] The induction coil may be located in any suitable position. Typically, the induction coil is arranged in a wall containing the heating compartment. This provides protection for the induction coil from environmental factors in the air and in the body, and from the components of the body.

[0028] The assembly may be arranged to operate, in use, with a fluctuating electromagnetic field having a magnetic flux density of between approximately 0.5 Tesla (T) and approximately 2.0 T at a point of peak concentration.

[0029] The power supply and circuitry may be configured to operate at a high frequency. Preferably, the power supply and circuitry may be configured to operate at a frequency between about 80 kHz and 500 kHz, preferably between about 150 kHz and 250 kHz, more preferably about 200 kHz.

[0030] The induction coil may typically comprise Litz wire or Litz cable, although the induction coil may comprise any suitable material.

[0031] The susceptor can be shaped to provide an aperture through which air can pass during use. This can be achieved by arranging the susceptor in the shape of a tube, i.e., providing a tubular susceptor. This is beneficial because the susceptor generates heat and effectively allows the air entering the body / cartridge to be preheated as it passes through the tube. It has been found that tubular susceptors are also better at generating heat than susceptors of other shapes because they have a closed circular electrical path. The susceptor also provides electromagnetic shielding to the user due to its shape and the way it interacts with electromagnetic influences thereon. Therefore, although a susceptor can be used solely to generate heat, typically, an inductively heatable susceptor has a tubular shape that forms at least a portion of the vent. Of course, the susceptor can also be another susceptor in addition to the susceptor of the body.

[0032] According to a second aspect, there is provided a steam generating system comprising: an induction heating assembly according to the first aspect; a body comprising a vaporisable substance and an inductively heatable susceptor; wherein the body is arranged in use within a heating compartment of the assembly.

[0033] The vaporizable substance can be any suitable substance that can form steam.This substance can comprise plant-derived material, and especially, this substance can comprise tobacco.Typically, the vaporizable substance is solid or semisolid tobacco substance.This allows susceptor to remain in place in body, makes it possible to repeatedly and consistently provide heating.The exemplary type of the solid that produces steam comprises powder, particulate, pellet, fragment, line, porous material or sheet material.

[0034] Preferably, the vaporizable substance may include an aerosol former. Examples of aerosol formers include polyols and their compounds, such as glycerol or propylene glycol. Typically, the vaporizable substance may include an aerosol former content of between about 5% and about 50% (on a dry weight basis). Preferably, the vaporizable substance may include an aerosol former content of about 15% (on a dry weight basis).

[0035] Furthermore, the vaporizable substance may be the aerosol-forming agent itself. In this case, the vaporizable substance may be a liquid. In this case, the body may have a liquid-retaining substance (e.g., a bundle of fibers, a porous material such as ceramic, etc.), which retains the liquid to be vaporized by the vaporizing device such as a heater and allows vapor to form and be released / emitted from the liquid-retaining substance to the air outlet for inhalation by the user.

[0036] When heated, the vaporizable substance can release volatile compounds. The volatile compounds can include nicotine or flavor compounds such as tobacco flavoring.

[0037] The body can be a capsule that, when in use, includes a vaporizable substance within a breathable shell. The breathable material can be an electrically insulating and non-magnetic material. The material can have high air permeability to allow air to flow through the material, which is resistant to high temperatures. Examples of suitable breathable materials include cellulose fibers, paper, cotton, and silk. The breathable material can also be used as a filter. Alternatively, the body can be a vaporizable substance wrapped in paper. Alternatively, the body can be a vaporizable substance held within a material that is impermeable but includes suitable perforations or openings to allow air to flow. Alternatively, the body can be the vaporizable substance itself. The body can be formed substantially in the shape of a rod.

[0038] The susceptors may be positioned within the body in any suitable location and manner. Typically, one or more susceptors are held within and surrounded by the vaporizable substance such that, when in use, the vaporizable substance forms a heat absorbing layer between the one or more susceptors and the outer surface of the assembly. This provides for efficient heating of the vaporizable substance while also limiting the amount of heat transferred to other components of the steam generating system. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Examples of induction heating assemblies are described in detail below with reference to the accompanying drawings, in which:

[0040] Figure 1 shows a schematic diagram of an exemplary steam generating apparatus;

[0041] Figure 2 shows an exploded view of an exemplary steam generating device;

[0042] Figure 3 Shown Figure 2 The steam generating device shown is along Figure 2 The cross section of plane AA in ;

[0043] Figure 4 An alternative exemplary steam generating device is shown along with Figure 3 a section through the same plane as shown;

[0044] Figure 5 Another exemplary steam generating device is shown along with Figure 3 a section through the same plane as shown;

[0045] Figure 6 Another exemplary steam generating device is shown along with Figure 3 a section through the same plane as shown;

[0046] Figure 7 Shown with Figure 6 A partial schematic diagram of an example corresponding to the example of ;

[0047] Figure 8 Shown with Figure 6 A partial schematic diagram of an alternative example corresponding to the example;

[0048] Figure 9 a schematic diagram showing a portion of an exemplary steam generating device with an exemplary airflow path; and

[0049] Figure 10 A schematic diagram of a portion of an exemplary steam generating device with alternative exemplary airflow paths is shown. DETAILED DESCRIPTION

[0050] Examples of vapor-generating devices are now described, including descriptions of example induction heating assemblies and example induction-heatable cartridges. Example methods of monitoring temperature in a vapor-generating device are also described.

[0051] Now refer to Figure 1 and Figure 2 , an exemplary steam generating device, generally designated 1, is Figure 1 Shown in assembled configuration and Figure 2 Shown in unassembled configuration.

[0052] The exemplary vapor-generating device 1 is a handheld device (hereby intended to mean a device that a user can hold in one hand and support unassisted) that includes an induction heating assembly 10, an induction-heatable cartridge 20, and a mouthpiece 30. The cartridge releases vapor when heated. Thus, vapor is generated by heating the induction-heatable cartridge using the induction heating assembly. The vapor can then be inhaled by the user at the mouthpiece.

[0053] In this example, the user inhales the vapor by drawing air into the device 1, through or around the inductively heatable cartridge 20 as it is heated, and out of the mouthpiece 30. This is achieved by positioning the cartridge in a heating compartment 12 defined by a portion of the inductive heating assembly 10, and, when the device is assembled, placing this compartment in gaseous connection with an air inlet 14 formed in the assembly and an air outlet 32 ​​in the mouthpiece. This allows air to be drawn through the device by applying negative pressure, typically generated by the user drawing air from the air outlet.

[0054] The cigarette cartridge 20 is a body comprising a vaporizable substance 22 and an inductively heatable susceptor 24. In this example, the vaporizable substance comprises one or more of tobacco, a humectant, glycerin, and propylene glycol. The susceptor is a plurality of conductive plates. In this example, the cigarette cartridge also comprises a layer or membrane 26 for containing the vaporizable substance and the susceptor, wherein this layer or membrane is breathable. In other examples, no membrane is present.

[0055] As described above, the induction heating assembly 10 is used to heat a cigarette cartridge 20. The assembly includes an induction heating device in the form of an induction coil 16 and a power supply 18. The power supply and the induction coil are electrically connected so that power can be selectively transferred between the two components.

[0056] In this example, the induction coil 16 is generally cylindrical, so that the form of the induction heating assembly 10 is also generally cylindrical. The heating compartment 12 is defined radially inwardly of the induction coil, has a base at the axial end of the induction coil, and has sidewalls around the radially inner side of the induction coil. The heating compartment opens at the axial end of the induction coil opposite to the base. When the steam generating device 1 is assembled, this opening is covered by the suction nozzle 30, wherein the opening leading to the air outlet 32 ​​is located at the opening of the heating compartment. In the example shown in the drawings, the air inlet 14 has an opening leading into the heating compartment at the base of the heating compartment.

[0057] As described above, to generate vapor, the cartridge 20 is heated. This is achieved by alternating current from the direct current supplied by the power supply 18 to the induction coil 16. The current flows through the induction coil, causing a controlled EM field to be generated in the area near the coil. The generated EM field provides a source for an external susceptor (in this case, the susceptor plate of the cartridge) to absorb EM energy and convert it into heat, thereby achieving induction heating.

[0058] In more detail, by supplying power to the induction coil 16, an electric current is caused to pass through the induction coil, thereby generating an EM field. As described above, the current supplied to the induction coil is an alternating current (AC) current. This results in heat generation within the cigarette cartridge because, when the cigarette cartridge is located in the heating compartment 12, the purpose is to arrange the susceptor plate (substantially) parallel to the radius of the induction coil 16, as shown in the figure, or at least to have a length component parallel to the radius of the induction coil. Therefore, when the cigarette cartridge is located in the heating compartment while the induction coil is supplied with AC current, the positioning of the susceptor plate causes eddy currents to be induced in each plate because the EM field generated by the induction coil is coupled to each susceptor plate. This results in heat generation in each plate by induction.

[0059] In this example, the plates of the cartridge 20 are in thermal communication with the vaporizable substance 22 through direct or indirect contact between each susceptor plate and the vaporizable substance. This means that when the susceptor 24 is inductively heated by the induction coil 16 of the induction heating assembly 10, heat is transferred from the susceptor 24 to the vaporizable substance 22 to heat the vaporizable substance 22 and produce vapor.

[0060] The induction coil 16 is embedded in the wall 28. This limits contact between the induction coil and the environment surrounding the induction coil. In use, heat from the heating compartment 12 enters the wall in which the induction coil is embedded, which also provides the side walls of the heating compartment. The induction coil also generates a small amount of heat due to the resistance of the coil.

[0061] In order to utilize this heat and transfer it from the induction coil to cool it, the air inlet 14 connected to the base of the heating compartment as described above passes through an opening at one end of the induction coil adjacent to where the nozzle 30 and the induction heating assembly 10 meet, through the wall in which the induction coil is embedded, to the opposite end of the induction coil, across this end to the opening in the base of the heating compartment. When the user draws air through the air outlet 32 ​​in the nozzle, the air passes through the air inlet (e.g., Figure 1 The smoke is drawn into the heating chamber, through the cartridge (if one is present), and through the air outlet (as indicated by arrow 48). Figure 1 50).

[0062] When the air in the air inlet 14 is cooler than the wall 28 in which the induction coil 16 is embedded, heat is transferred from the wall (and therefore from the induction coil) to the air. This warms the air and cools the wall and induction coil. As a result, the air passing through the cigarette cartridge is warmer than the air outside the vapor generating device 1.

[0063] exist Figure 1 and Figure 2 In the example shown, the air inlet 14 is surrounded by an outer wall 34. The outer wall provides a barrier between the air inlet and the outside of the steam generating device 1. If the outer wall is warmer than the air in the air inlet, heat is also transferred from the outer wall to the air in the air inlet.

[0064] As described above, air is introduced from the air inlet 14 into the heating compartment 12, as indicated by arrow 48. The cartridge 20 fits snugly within the heating compartment. Therefore, air must pass through the cartridge as it passes through the heating compartment containing the cartridge. Consequently, air flow around the cartridge is restricted, and there is no dedicated airflow path around the cartridge between the cartridge and the wall 28, which houses the induction coil 16. Because the air entering the heating compartment is already warmed before entering the heating compartment and the cartridge, this limits the amount of heat loss from the cartridge to the air, thereby keeping the cartridge warmer.

[0065] exist Figure 2 In the embodiment of the present invention, an EM shield 36 is embedded in the wall 28 in which the induction coil 16 is embedded. The EM shield is located radially outward from the induction coil. When the steam generating device 1 is in use, the EM shield will warm due to the heat generated by the induction coil and the heat in the heating compartment 12, and may also warm due to the current generated in the shield during the shielding process.

[0066] Figure 3 Shown along Figure 2 This shows a circular body, and thus a generally cylindrical shape of the steam generating device. The heating compartment 12 is located in the center, surrounded by a wall 28, in which the induction coil 16 is embedded, together with the EM shield 36. Figure 2 , it can be seen that the EM shield is positioned around the induction coil, radially outside the coil.

[0067] The vent 14 is positioned around the wall 28, which has the induction coil 16 and EM shield 36 embedded within it. The vent is divided into a plurality of arcs 38, each of which is provided with an airflow path. The vent is divided by ribs 40. These ribs connect between the wall 28, which has the induction coil and EM shield embedded within it, and an outer wall 34, which surrounds the vent radially outside it.

[0068] Figure 4 An alternative exemplary steam generating device is shown with Figure 3 The device is thus still circular with the heating compartment 12 located in the center of the device. Figure 2 and Figure 3 The same configuration of the steam generating device shown is also surrounded by a wall 28, which embeds the induction coil 16 and the EM shield 36. In this example, instead of an arc forming the airflow path of the vent, the vent 14 is provided by a plurality of circular holes 39 (e.g. Figure 4 4 ), these circular holes are evenly distributed radially outward from the EM shield in a circular pattern. Each hole provides an airflow path and is separated from adjacent holes by ribs 40, which connect the wall to the outer wall 34, which houses the coil and EM shield and forms the outer wall of the steam generating device.

[0069] Figure 5 The same cross section of a further alternative exemplary steam generating device is shown. The device is also circular, with the heating compartment 12 located in the center. A wall 28 surrounds the heating compartment. The induction coil 16 is embedded in this wall. However, instead of Figure 3 In the example shown, the EM shield is also embedded in this wall, where the EM shield 36 is embedded in the outer wall 34. The outer wall is separated from the wall in which the coil is embedded by the vent hole 14. Figure 3 As in the example shown, the vent is divided into a plurality of arcs 38 separated by ribs 40. In this configuration, the arcs 38 can be provided by metal tubes. In this case, the metal tubes can act as susceptors and provide preheating to the air entering the heating compartment 12. The metal tubes can also act as EM shields.

[0070] Figure 6Another alternative exemplary steam generating device is shown along Figures 3 to 5 In this example, the device has a cross section with Figure 5 The same structure as in the example of FIG. 1 is shown, but instead of being an outer wall, the wall in which the EM shield is embedded is an intermediate wall 42. Radially outward from this intermediate wall is an outer wall 34. Vent holes 14 are located between the outer wall and the intermediate wall, and vent holes are located between the intermediate wall and the wall 28, which embeds the induction coil 16 and surrounds the heating compartment 12. Each vent hole is divided into a plurality of arcs 38 by ribs 40 extending between the respective walls of the respective vent hole. Each arc also provides an airflow path.

[0071] exist Figure 6 In the example shown, the vents 14 may have one of a variety of arrangements. Figure 7 and Figure 8 Two such arrangements are shown.

[0072] Figure 7 shows a similar Figure 6 The arrangement of an exemplary steam generating device is shown in cross section. Figure 7 In the arrangement shown, the steam generating device has an outer wall 34 that provides the outer wall of the device. Radially inwardly of the outer wall is an intermediate wall 42 that has a radial spacing from the outer wall and a radial spacing from the wall 28, and that has the induction coil 16 embedded therein. Radially inwardly of the intermediate wall is a wall that has the induction coil embedded therein and that provides the side wall of the heating compartment 12 defined radially inwardly of the wall.

[0073] A vent hole 14 leads from the outside of the device to the heating compartment. Figure 7 A single airflow path, indicated at 48 in the figure, extends through the vent. This path passes through the outer wall 34 at a position aligned with the axial end of the heating compartment 12 and enters the steam generating device. The path then passes between the outer wall and the intermediate wall 42 to a position aligned with the opposite axial end of the heating compartment. At this position, a passage exists between the gap provided by the radial spacing between the outer wall and the intermediate wall and the gap provided by the radial spacing between the intermediate wall and the wall 28, which is embedded with the induction coil 16. The airflow path passes through this passage and returns between the intermediate wall and the wall to a position also aligned with the initial axial end of the heating compartment, but at a smaller radial spacing from the heating compartment than when the path entered the steam generating device, which is embedded with the induction coil. The path then follows another passage to enter the heating compartment at its axial end.

[0074] Figure 8 shows a similar Figure 6 An exemplary steam generating device is shown in cross section. Figure 7 An alternative arrangement to the one shown. Figure 7As shown in the arrangement Figure 8 In the arrangement shown, the steam generating device has an outer wall 34 that provides the outer wall of the device. Radially inwardly of the outer wall is an intermediate wall 42 that has a radial spacing from the outer wall and a radial spacing from the wall 28, and that has the induction coil 16 embedded therein. Radially inwardly of the intermediate wall is a wall that has the induction coil embedded therein and that provides the side wall of the heating compartment 12 defined radially inwardly of the wall.

[0075] and Figure 7 Same, in Figure 8 In the embodiment, the vent 14 leads from the outside of the device to the heating compartment. However, instead of Figure 7 A single airflow path 48, Figure 8 The arrangement shown has Figure 8 The airflow path, indicated at 50, has a common starting point and a common end point, but has two generally parallel sections between the starting point and the end point. The path passes through the outer wall 34 and enters the steam generating device at a position aligned with the axial end of the heating compartment 12. The path then diverges. One section of the path passes between the outer wall and the middle wall 42, into a gap provided by the radial spacing between these walls. Another section of the path passes through a passageway into a gap provided by the radial spacing between the middle wall and the wall 28, which houses the induction coil 16. This section of the path then passes through this gap. The two sections rejoin at a position aligned with the opposite end of the heating compartment 12. This is achieved by the section of the path passing between the outer wall and the middle wall, then through the passageway in the middle wall, joining the section passing between the middle wall and the wall to a position corresponding to the opposite axial end of the heating compartment, which houses the induction coil. The path continues into the heating compartment at the axial end of the heating compartment along a common end section.

[0076] and Figure 6 As shown in the example, Figure 7 and Figure 8 The arrangement shown has ribs ( Figure 7 and Figure 8 ), these ribs connect and support a plurality of different walls that form arc segments in the ventilation hole 14.

[0077] Figure 9 and Figure 10 Each shows an exemplary air flow path that can be used in a steam generating device.Each of these figures shows a cylinder representing a wall 28 within which an induction coil is embedded.

[0078] Figure 9 An airflow path 44 is shown, which passes through the vent ( Figure 9 and Figure 10The airflow paths are provided in a zigzag pattern around the wall 28. This is intended to mean that the paths have parallel sections aligned with the longitudinal axis of the cylindrical wall and are joined at the ends of the parallel sections by curved sections of the airflow path to adjacent sections. In this configuration, one or more airflow paths are arranged around the entire wall.

[0079] Figure 10 An airflow path 46 is shown. This airflow path is also provided by vents (not shown). The airflow path spirals around the wall 28 from one axial end of the wall to the opposite axial end of the wall.

Claims

1. An induction heating assembly (10) for a steam generating device (1), the heating assembly comprising: external ontology; an induction coil (16) disposed inside the outer body; a heating compartment (12) defined within the interior of the induction coil and arranged, in use, to receive a body (20) comprising a vaporizable substance (22) and an inductively heatable susceptor (24); wherein the outer body and the induction coil (16) are separated from each other, and A vent (14) is defined and arranged to allow a flow of air into the heating compartment (12) such that the air is heated before entering the body (20) in use.

2. The induction heating assembly (10) according to claim 1, wherein The vent (14) is shaped to direct air flow along the induction coil (16) and then to the heating compartment (12).

3. The induction heating assembly (10) according to claim 1 or 2, further comprising one or more spacers (42) arranged between the outer body and the induction coil (16) to define two or more layers of vents (14).

4. The induction heating assembly (10) of any preceding claim, further comprising ribs (40) supporting the outer body and induction coil (16).

5. The induction heating assembly (10) of any preceding claim, further comprising structures (40, 42) in the vent (14), the structures being arranged to define one or more airflow paths (44, 46, 48, 50).

6. The induction heating assembly (10) according to any preceding claim, wherein The airflow paths (44, 46, 48, 50) are arranged as one or more of the following: a spiral around the induction coil (16); a zigzag shape in the longitudinal direction of the induction coil (16); and A zigzag shape in the transverse direction of the induction coil (16).

7. The induction heating assembly (10) according to any one of claims 5 and 6, wherein: The airflow paths (44, 46, 48, 50) cover more than 50% of the outer surface of the induction coil (16).

8. The induction heating assembly (10) of any preceding claim, further comprising an electromagnetic shield (36) arranged substantially around the circumference of the outermost vent (14).

9. An induction heating assembly (10) according to any preceding claim, wherein The induction coil (16) is disposed generally within a wall (28) housing the heating compartment (12).

10. The induction heating assembly (10) according to any preceding claim, wherein The induction coil (16) is embedded in a wall (28) of the heating compartment (12).

11. The induction heating assembly (10) according to any preceding claim, wherein The heating compartment (12) is adjacent to the induction coil.

12. The induction heating assembly (10) according to any preceding claim, wherein A vaporizable substance (22) and an inductively heatable susceptor (24) are contained by the body (20).

13. The induction heating assembly (10) according to any preceding claim, wherein An inductively heatable susceptor (24) has a tubular shape forming at least a portion of the vent (14).

14. A steam generating system (1), comprising: The induction heating assembly (10) according to any one of claims 1 to 13; a body (20) comprising a vaporizable substance (22) and an inductively heatable susceptor (24); The body (20) is arranged in a heating compartment (12) of an induction heating assembly (10) when in use.

15. The steam generating system (1) according to claim 14, wherein: The vaporizable substance (22) is a solid or semi-solid tobacco substance, and / or The susceptor (24) is held within and surrounded by the vaporizable substance such that the vaporizable substance forms a heat absorbing layer between the susceptor and an outer surface of the assembly (10) in use.

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