Patent Application
20200253283
The present disclosure relates to an induction heating assembly for a vapour generating device. Embodiments of the present disclosure also relate to a vapour generating device.
Devices which heat, rather than burn, a vaporisable substance to produce a vapour for inhalation have become popular with consumers in recent years.
Such devices can use one of a number of different approaches to provide heat to the substance. One such approach is to provide a vapour generating device which employs an induction heating system. In such a device, an induction coil (hereinafter also referred to as an inductor) is provided with the device and a susceptor is provided with the vaporisable substance. Electrical energy is provided to the inductor when a user activates the device which in turn generates an alternating electromagnetic field. The susceptor couples with the electromagnetic field and generates heat which is transferred, for example by conduction, to the vaporisable substance and vapour is generated as the vaporisable substance is heated.
Such an approach has the potential to provide better control of heating and therefore vapour generation. However, a shortcoming of the use of an induction heating system is that leakage of the electromagnetic field generated by the induction coil may occur and there is, therefore, a need to address this shortcoming.
According to a first aspect of the present disclosure, there is provided an induction heating assembly for a vapour generating device, the induction heating assembly comprising:
The low-pass filter is electrically connected to the induction coil to act as a low-pass filter for the induction coil. The low-pass filter is also structured to provide an electromagnetic shield for the induction coil. In this way, a single electronic component can be provided to act as both a low-pass filter of electronic control circuitry of the induction heating assembly and as an electromagnetic shield. The construction of the induction heating assembly is thus simplified due to the need to use fewer electronic components. The use of fewer electronic components leads to a reduction in both the size and the manufacturing cost of the induction heating assembly.
According to a second aspect of the present disclosure, there is provided a vapour generating device comprising:
The induction heating assembly may comprise a power source, for example a battery, arranged to provide power to the induction coil. The induction heating assembly may comprise a heating compartment in communication with an air outlet. The heating compartment may be arranged to receive an induction heatable cartridge.
The low-pass filter may be positioned between the induction coil and the power source.
The low-pass filter may be positioned between the induction coil and the air outlet.
The induction heating assembly may comprise an air inlet in communication with the heating compartment and the low-pass filter may be positioned between the air inlet and the power source. Such an arrangement allows the provision of a compact induction heating assembly and, hence, of a compact vapour generating device.
The induction heating assembly may comprise one or more resonant capacitors, and the low-pass filter may be positioned between the induction coil and the one or more resonant capacitors. The one or more resonant capacitors are, thus, protected from electromagnetic exposure.
The low-pass filter may comprise a coil. The low-pass filter coil may comprise a flat coil which may extend in a plane defined by the coil winding direction.
The induction coil may be helical.
The low-pass filter coil may be positioned at an axial end of the helical induction coil. The plane of the low-pass filter coil may be substantially perpendicular to the axial direction of the helical induction coil.
The low-pass filter may be arranged to substantially cover an elongate side of the helical induction coil.
The low-pass filter may comprise a plate member comprising a ferrimagnetic material and the low-pass filter coil may be positioned on the plate member. Such an arrangement increases the inductance of the low-pass filter and EM shield performance.
The low-pass filter may comprise two plate members comprising a ferrimagnetic material and the low-pass filter coil may be positioned between the plate members. Such an arrangement again increases the inductance of the low-pass filter and EM shield performance.
The or each ferrimagnetic plate member may be circular, for example may comprise a ferrimagnetic disk, although other shapes can be employed.
The or each ferrimagnetic plate member may comprise a ferrimagnetic material having a low electrical conductivity and a high magnetic permeability, for example a ferrite ceramic.
The induction heating assembly may be arranged to operate in use with a fluctuating electromagnetic field having a magnetic flux density of between approximately 20 mT and approximately 2.0 T at the point of highest concentration.
The induction heating assembly may include a power source and circuitry which may be configured to operate at a high frequency. The power source and circuitry may be configured to operate at a frequency of between approximately 80 kHz and 500 kHz, possibly between approximately 150 kHz and 250 kHz, and possibly at approximately 200 kHz. The power source and circuitry could be configured to operate at a higher frequency, for example in the MHz range, depending on the type of inductively heatable susceptor that is used.
The low-pass filter may have a cut-off frequency between approximately 100 kHz and 600 kHz. In some embodiments, the low-pass filter may have a cut-off frequency of approximately 250 kHz. In other embodiments, the low-pass filter may have a cut-off frequency between approximately 280 kHz and 300 kHz.
Whilst the induction coil may comprise any suitable material, typically the induction coil may comprise a Litz wire or a Litz cable.
Whilst the induction heating assembly may take any shape and form, it may be arranged to take substantially the form of the induction coil, to reduce excess material use. As noted above, the induction coil may be substantially helical in shape.
The circular cross-section of a helical induction coil facilitates the insertion of an induction heatable cartridge into the induction heating assembly and ensures uniform heating of the induction heatable cartridge. The resulting shape of the induction heating assembly is also comfortable for the user to hold.
The induction heatable cartridge may comprise one or more induction heatable susceptors. The or each susceptor may comprise one or more, but not limited, of aluminium, iron, nickel, stainless steel and alloys thereof, e.g. Nickel Chromium or Nickel Copper. With the application of an electromagnetic field in its vicinity, the or each susceptor may generate heat due to eddy currents and magnetic hysteresis losses resulting in a conversion of energy from electromagnetic to heat.
The induction heatable cartridge may comprise a vapour generating substance inside an air permeable shell. The air permeable shell may comprise an air permeable material which is electrically insulating and non-magnetic. The material may have a high air permeability to allow air to flow through the material with a resistance to high temperatures. Examples of suitable air permeable materials include cellulose fibres, paper, cotton and silk. The air permeable material may also act as a filter. Alternatively, the induction heatable cartridge may comprise a vapour generating substance wrapped in paper. Alternatively, the induction heatable cartridge may comprise a vapour generating substance held inside a material that is not air permeable, but which comprises appropriate perforations or openings to allow air flow. Alternatively, the induction heatable cartridge may consist of the vapour generating substance itself. The induction heatable cartridge may be formed substantially in the shape of a stick.
The vapour generating substance may be any type of solid or semi-solid material. Example types of vapour generating solids include powder, granules, pellets, shreds, strands, particles, gel, strips, loose leaves, cut filler, porous material, foam material or sheets. The substance may comprise plant derived material and in particular, the substance may comprise tobacco.
The vapour generating substance may comprise an aerosol-former. Examples of aerosol-formers include polyhydric alcohols and mixtures thereof such as glycerine or propylene glycol. Typically, the vapour generating substance may comprise an aerosol-former content of between approximately 5% and approximately 50% on a dry weight basis. In some embodiments, the vapour generating substance may comprise an aerosol-former content of approximately 15% on a dry weight basis.
Also, the vapour generating substance may be the aerosol-former itself. In this case, the vapour generating substance may be a liquid. Also, in this case, the induction heatable cartridge may include a liquid retaining substance (e.g. a bundle of fibres, porous material such as ceramic, etc.) which retains the liquid to be vaporized and allows a vapour to be formed and released/emitted from the liquid retaining substance, for example towards the air outlet for inhalation by a user.
Upon heating, the vapour generating substance may release volatile compounds. The volatile compounds may include nicotine or flavour compounds such as tobacco flavouring.
Since the induction coil produces an electromagnetic field when operating to heat a susceptor, any member comprising an induction heatable susceptor will be heated when placed in proximity to the induction coil in operation, and as such there is no restriction on the shape and form of the induction heatable cartridge being received in the heating compartment. In some embodiments, the induction heatable cartridge may be cylindrical in shape and as such the heating compartment is arranged to receive a substantially cylindrical vaporisable article.
The ability of the heating compartment to receive a substantially cylindrical induction heatable cartridge to be heated is advantageous as, often, vaporisable substances and tobacco products in particular, are packaged and sold in a cylindrical form.
Embodiments of the present disclosure will now be described by way of example only and with reference to the accompanying drawings.
Referring initially to
The vapour generating device 10 comprises an induction heating assembly 20 for heating a vapour generating (i.e. vaporisable) substance. The induction heating assembly 20 comprises a generally cylindrical heating compartment 22 which is arranged to receive a correspondingly shaped generally cylindrical induction heatable cartridge 24 comprising a vaporisable substance 26 and one or more induction heatable susceptors 28. The induction heatable cartridge 24 typically comprises an outer layer or membrane to contain the vaporisable substance 26, with the outer layer or membrane being air permeable. For example, the induction heatable cartridge 24 may be a disposable cartridge 24 containing tobacco and at least one induction heatable susceptor 28.
The induction heating assembly 20 comprises a helical induction coil 30, having first and second axial ends 38, 40, which extends around the cylindrical heating compartment 22 and which can be energised by the power source 16 and control circuitry 17. The control circuitry 17 includes, amongst other electronic components, an inverter which is arranged to convert a direct current from the power source 16 into an alternating high-frequency current for the induction coil 30. As will be understood by those skilled in the art, when the induction coil 30 is energised by the alternating high-frequency current, an alternating and time-varying electromagnetic field is produced. This couples with the one or more induction heatable susceptors 28 and generates eddy currents and/or hysteresis losses in the one or more induction heatable susceptors 28 causing them to heat up. The heat is then transferred from the one or more induction heatable susceptors 28 to the vaporisable substance 26, for example by conduction, radiation and convection.
The induction heatable susceptor(s) 28 can be in direct or indirect contact with the vaporisable substance 26, such that when the susceptors 28 is/are inductively heated by the induction coil 30 of the induction heating assembly 20, heat is transferred from the susceptor(s) 28 to the vaporisable substance 26, to heat the vaporisable substance 26 and produce a vapour. The vaporisation of the vaporisable substance 26 is facilitated by the addition of air from the surrounding environment through the air inlets 18. The vapour generated by heating the vaporisable substance 26 then exits the heating compartment 22 through the air outlet 14 and may, for example, be inhaled by a user of the device 10 through the mouthpiece. The flow of air through the heating compartment 22, i.e. from the air inlets 18, through the heating compartment 22, along an inhalation passage 32 of the induction heating assembly 20, and out of the air outlet 14, can be aided by negative pressure created by a user drawing air from the air outlet 14 side of the device 10 using the mouthpiece.
The induction heating assembly 20 comprises a low-pass filter 34 electrically connected to the induction coil 30. The low-pass filter 34 acts as a low-pass filter for the induction coil 30 and is structured to provide an electromagnetic shield for the induction coil 30 to thereby reduce leakage of the electromagnetic field generated by the induction coil 30. The low-pass filter 34 typically comprises a flat coil 36, for example as illustrated in
In the embodiment illustrated in
In the illustrated embodiment, the induction heating assembly 20 includes one or more resonant capacitors 42, and the low-pass filter coil 36 is advantageously positioned between the induction coil 30 and the one or more resonant capacitors 42 to protect the resonant capacitor(s) 42 from exposure to the electromagnetic field generated by the induction coil 30.
In another embodiment illustrated in
As mentioned above, and with reference to
The ferrimagnetic disks 44, 44a, 44b comprise a ferrimagnetic material having a low electrical conductivity and a high magnetic permeability. A ferrite ceramic is one example of a suitable material. Again, it will be understood by those skilled in the art that the part of the coil 36 that extends radially outwardly from the centre region of the coil 36 does not contact the underlying circumferentially extending parts of the coil 36 that lie beneath it.
Although exemplary embodiments have been described in the preceding paragraphs, it should be understood that various modifications may be made to those embodiments without departing from the scope of the appended claims. Thus, the breadth and scope of the claims should not be limited to the above-described exemplary embodiments.
Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like, are to be construed in an inclusive as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.
| Number | Date | Country | Kind |
|---|---|---|---|
| 17210815.1 | Dec 2017 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2018/086170 | 12/20/2018 | WO | 00 |
