阅读说明：本技术 电加热组件、气溶胶生成装置和用于电阻加热气溶胶形成基质的方法
(Electrical heating assembly, aerosol-generating device and method for resistively heating an aerosol-forming substrate
) 是由 J·C·库拜特
O·米罗诺夫 于 2018-06-27 设计创作，主要内容包括：本发明涉及一种用于电阻加热气溶胶形成基质的气溶胶生成装置的电加热组件。加热组件包括被配置成提供AC驱动电流的控制电路。加热组件还包括用于加热气溶胶形成基质的电阻加热元件。加热元件与控制电路可操作地耦合,并且被配置成当使由控制电路提供的AC驱动电流通过加热元件时,由于焦耳加热而变热。本发明还涉及一种用于气溶胶形成基质的气溶胶生成装置,其中气溶胶生成装置包括根据本发明的加热组件。本发明还提供一种使AC驱动电流通过电阻加热元件来电阻加热气溶胶形成基质的方法。(The present invention relates to an electrical heating assembly for an aerosol-generating device for electrical resistance heating of an aerosol-forming substrate. The heating assembly includes a control circuit configured to provide an AC drive current. The heating assembly further comprises a resistive heating element for heating the aerosol-forming substrate. The heating element is operatively coupled with the control circuit and is configured to heat up due to joule heating when an AC drive current provided by the control circuit is passed through the heating element. The invention also relates to an aerosol-generating device for an aerosol-forming substrate, wherein the aerosol-generating device comprises a heating assembly according to the invention. The invention also provides a method of resistively heating an aerosol-forming substrate by passing an AC drive current through a resistive heating element.)
1. An aerosol-generating device for an aerosol-forming substrate, the aerosol-generating device comprising an electrical heating assembly for resistive heating of the aerosol-forming substrate, the heating assembly comprising:
-a control circuit configured to provide an AC drive current having a frequency in a range between 500kHz and 30 MHz;
-a resistive heating element for heating the aerosol-forming substrate, wherein the heating element is operatively coupled with the control circuit by a wire and is configured to heat up as a result of joule heating when an AC drive current provided by the control circuit is passed through the heating element.
2. The apparatus of claim 1, further comprising a power source operably connected to the control circuit.
3. The device according to any one of the preceding claims, wherein the heating element has a blade configuration or a rod configuration or a pin configuration or a grid configuration or a core configuration.
4. The device of any preceding claim, wherein the heating element comprises at least one resistive conductor path or a plurality of resistive conductor paths in parallel with one another for passing an AC drive current therethrough.
5. A device according to claim 4, wherein the at least one resistive conductor path or at least one of the plurality of resistive conductor paths is formed by at least one cross-sectional-wise slit of the heating element.
6. A device according to any one of claims 4 or 5, wherein the at least one resistive conductor path or at least one of the plurality of resistive conductor paths is formed by at least one slit, wherein the heating element is completely interrupted by the slit along a depth extension of the slit and only partially interrupted by the slit along a length extension of the slit.
7. The device of any one of the preceding claims, further comprising an electrically conductive connector operatively coupling the control circuit with the heating element, wherein the connector has a lower AC resistance than the heating element.
8. The device of claim 7, wherein the relative permeability of the electrically conductive material of the connector is lower than the relative permeability of the electrically conductive material of the heating element.
9. The apparatus of any preceding claim, further comprising a heat sink thermally coupled to at least one of the control circuitry or the connector.
10. The device of any preceding claim, wherein the control circuit comprises at least one bypass capacitor connected in parallel with the heating element.
11. A method for resistively heating an aerosol-forming substrate to generate an aerosol, the method comprising the steps of:
-providing an aerosol-forming substrate to be heated;
-providing a resistive heating element for heating the aerosol-forming substrate, the heating element being configured to heat up due to joule heating when an AC drive current is passed therethrough;
-providing the aerosol-forming substrate in close proximity to or in contact with the aerosol-forming substrate;
-providing an AC drive current with a frequency in a range between 500kHz and 30 MHz; and
-passing an AC drive current through the heating element.
12. The method of claim 11, wherein the step of providing an AC drive current comprises providing the AC drive current using a switching power amplifier.
13. The method of claim 12, wherein the step of providing an AC drive current using a switching power amplifier comprises operating the switching power amplifier at a duty cycle in a range between 20% and 99%.
Examples
8-9 schematically illustrate exemplary embodiments of multilayer heating blades according to the present disclosure; and
FIGS. 10-11 schematically illustrate exemplary embodiments of multilayer heater rods according to the present invention.
Figure 1 schematically shows an exemplary embodiment of an aerosol-generating device 1 comprising an electrical heating assembly 100 according to the present invention for resistively heating an aerosol-forming substrate 210.
The aerosol-generating device 1 comprises a device housing 10 comprising a receiving chamber 20 at the proximal end 2 of the device 1 for receiving an aerosol-forming substrate 210 to be heated. In the present embodiment, the aerosol-forming substrate 210 is a solid aerosol-forming substrate comprising tobacco. The substrate 210 is part of a rod-shaped aerosol-generating article 200. The article 200 is shaped like a conventional cigarette and is configured to be received in the receiving chamber 20 of the device 1. In addition to the aerosol-forming substrate 210, the article 200 comprises a support element 220, an aerosol-cooling element 230 and a filter element 240. All these elements are arranged sequentially to the aerosol-forming substrate 210, with the substrate arranged at the distal end of the article 200 and the filter element arranged at the proximal end of the article 200. The substrate 210, support element 220, aerosol-cooling element 230 and filter element 240 are surrounded by a wrapper forming the outer circumferential surface of the article 200.
The main concept of the heating assembly according to the invention is based on passing an AC drive current through the resistive heating element 110, which in turn is in thermal proximity or even in close contact with the aerosol-forming substrate 210. The use of AC drive currents advantageously allows the use of large and therefore mechanically robust heating elements that still provide sufficient joule heating (due to the skin effect) to reach temperatures within a range suitable for heating the aerosol-forming substrate 210.
In the embodiment of the heating assembly 100 as shown in fig. 1, the heating element 110 is a blade made of a solid electrically conductive material having an AC resistance R in the range between 10m Ω and 1500m Ω for an AC drive having a frequency in the range between 500kHz and 30 MHz. Preferably, the heating blade 210 is made of a solid metal, such as stainless steel, e.g. AISI420, or permalloy, e.g. permalloy C. Advantageously, the electrical resistance in this range is sufficiently high for heating the aerosol-forming substrate 210. At the same time, the heating element 110 provides sufficient mechanical stability to come into and out of contact with the aerosol-forming substrate 210 without the risk of deformation or breakage. In particular, the blade-like configuration of the heating element 110 enables easy penetration into the aerosol-forming substrate 210 when the aerosol-generating article 200 is inserted into the receiving chamber 20 of the aerosol-generating device 1.
As can also be seen in fig. 1, the heating blade 110 is fixedly arranged within the device housing 10 of the aerosol-generating device 1, extending centrally into the receiving chamber 20. The tapered proximal tip portion at the proximal end 111 of the heating blade 110 faces towards the receiving opening at the proximal end 2 of the device 1.
In addition to the heating element 110, the heating assembly 100 includes a control circuit 120 operatively coupled with the heating element 110 and configured to provide an AC drive current in a range between 500kHz and 30 MHz. Thus, when an AC drive current is passed through the heating element 110, the heating element heats up due to joule heating.
The control circuit 120, and thus the heating process, is powered by the DC power supply 140. In the present embodiment, the DC power source 140 is a rechargeable battery disposed within the device housing 10 at the distal end 3 of the device 1. The battery may be part of the heating assembly 100 or part of the global power supply of the aerosol-generating device 1, which may also be used for other components of the device 1.
Figure 2 schematically shows a first embodiment of an electrical circuit diagram of a heating assembly 100 as used in the aerosol-generating device 1 shown in figure 1. According to this first embodiment, the control circuit 120 basically comprises a DC/AC inverter 121 for inverting the DC current/voltage IDC/+ VDC supplied by the DC power supply 140 into an AC drive current in the range between 500kHz and 30MHz for operating the heating element 110.
In the present embodiment, the DC/AC inverter 121 includes a class E amplifier. The class E amplifier includes: a transistor switch T1, for example, a metal-oxide semiconductor field effect transistor (MOSFET); a transistor switch driver circuit PG; and an LC load network. The LC load network comprises a series connection of a capacitor C1 and an inductor L1. Further, the LC load network includes a parallel capacitor C2 connected in parallel with the transistor switch T1 and in parallel with the series connection of the capacitor C1 and the inductor L1. Furthermore, the control circuit comprises a choke coil L2 for supplying a DC supply voltage + VDC to the class-E amplifier. As also mentioned above, the heating element not only constitutes a resistance, but also a (small) inductance. In the circuit diagram according to fig. 2, the heating element 110 is therefore represented by a series connection of a resistor R110 and an inductor L110. The resistive load R110 of the heating element 110 may also represent the resistive load of the inductor L1. The small number of these components allows keeping the volume of the DC/AC inverter 121 very small, and therefore the overall volume of the heating assembly 100 also very small.
The general operating principle of class E amplifiers is generally well known. For more details on Class E amplifiers and their general operating principle, reference is made, for example, to the article "Class E RF power amplifiers" by Nathan o. The foregoing article also describes the correlation equations to be considered for determining the dimensions of the various components of the DC/AC inverter 121. In the first embodiment as shown in fig. 2, the inductance of inductor L1 may be in the range between 50nH (nano henry) and 200nH (nano henry), the inductance of inductor L2 may be in the range between 0.5 μ H (micro henry) and 5 μ H (micro henry), and the capacitance of capacitors C1 and C2 may be in the range between 1nF (nano farad) and 10nF (nano farad).
Fig. 3 schematically shows a second embodiment of the circuit diagram of the heating assembly 100. The circuit diagram according to this second embodiment is very similar to the first embodiment shown in fig. 2. Accordingly, the same or similar components are denoted by the same reference numerals. In addition to the circuit diagram of fig. 2, the circuit diagram of the second embodiment comprises a bypass capacitor C3 connected in parallel with the heating element 110, i.e. in parallel with the series connection of the resistor R110 and the inductor L110. Advantageously, the capacitance of the bypass capacitor C3 is larger than the capacitance of the capacitor C1 of the LC network, in particular at least two times larger, preferably at least five times larger, most preferably at least ten times larger. Accordingly, the bypass capacitor C3 and the inductor L110 of the heating element 110 form an LC resonator through which most of the AC drive current passes, while only a small portion of the AC drive current passes through the transistor switch via the inductor L1 and the capacitor C1 of the LC network. Because of this, the bypass capacitor C3 advantageously reduces heat transfer from the heating element 110 to the control circuit 120, and in particular to the transistor switch T1. The bypass capacitor C3 is disposed proximate to the heating element 110, but may be remote from the remainder of the control circuit 120. The remainder of the control circuitry 120 is preferably disposed on a PCB (printed circuit board).
Heat transfer from the heating element 110 to the control circuit 120 may be further reduced by providing an electrically conductive connector that operatively couples the control circuit 120 with the heating element 110, wherein the AC resistance of the connector 130 is lower than the AC resistance of the heating element 110. This may be accomplished, for example, by selecting suitable conductive materials for the connector 130 and the heating element 110. In particular, the respective materials may be selected such that the relative magnetic permeability of the electrically conductive material of the connector 130 is lower than the relative magnetic permeability of the electrically conductive material of the heating element 110. For this reason, the skin depth is larger, and therefore the AC resistance in the connector 130 is lower than in the heating element 110. Preferably, the conductive material of the connector 130 is paramagnetic, while the conductive material of the heating element 110 is ferromagnetic. In the embodiment shown in fig. 1, the heating element 120 is operatively coupled by two connector elements 131, 132 (which are made of tungsten, for example), while the heating element 110 is made of permalloy C.
Additionally or alternatively, the heating assembly may include a heat sink thermally coupled to at least one of the control circuit 120 or the connector 130 to reduce any adverse thermal effects on the control circuit 120. For example, the inductor L1 of the LC circuit shown in fig. 2 and 3 may be embedded in a heat absorbing material, for example, in high temperature cement.
Fig. 4 shows an enlarged view of a resistance heating blade 110 as used in the heating assembly 110 according to fig. 1. In this embodiment, the heater blade includes a central longitudinal slit 113 extending from the distal end 112 of the heater blade towards the proximal end 111. However, the heating blade 110 is only partially interrupted by the slits 113 along the length extension of the blade. In contrast, the vane is completely interrupted by the slit 113 along the depth or thickness extension of the vane 110. As a result, the heated blades provide a U-shaped conductor path (indicated by the dashed double arrow) for the AC drive current through the blades. At its distal end 112, the conductor path comprises two feed points 114 for supplying an AC drive current.
At its proximal end 111, the heating blade 110 comprises a tapered tip portion, such that the blade easily penetrates into the aerosol-forming substrate 210 of the article 200.
The heating blade 110 may have a length in the range between 5mm and 20mm, in particular between 10mm and 15mm, a width in the range between 2mm and 8mm, in particular between 4mm and 6mm, and a thickness in the range between 0.2mm and 0.8mm, in particular between 0.25mm and 0.75 mm.
Fig. 5 shows a second embodiment of the heating blade 110. In contrast to fig. 4, the heating blade 110 according to this second embodiment comprises two longitudinal slits 113.1, 113.2 extending parallel to each other along a length portion of the heating blade 110. As a result, the heating blade 110 provides two parallel U-shaped conductor paths for the AC drive current through the blade, where the two paths indicated by the dashed double arrows have one common branch. Accordingly, the conductor path comprises a total of three feed points 114 for supplying the AC drive current. Having two paths in parallel advantageously increases the amount of heat dissipated and, therefore, improves heating efficiency.
Fig. 6 and 7 show third and fourth embodiments of heating blades 110, which also aim to improve heat dissipation and, therefore, heating efficiency. In both embodiments, the heating blade 110 includes a plurality of cross-sectional-direction slits 113 that create a single conductor path having a serpentine or saw-tooth configuration. Due to this, the total length of the conductor path, and thus the total amount of heat dissipated, is significantly increased compared to the configuration shown in fig. 4.
According to a third embodiment shown in fig. 6, the heating blade 110 comprises two longitudinal slits 113.1, 113.2, which are parallel to each other along a length portion of the heating blade 110. Two longitudinal slits 113.1, 133.2 extend from the proximal end 111 towards the distal end 112 of the blade 110, but do not reach said distal end. Furthermore, the heating blade 110 comprises a U-shaped slit 113.3 at least partially enclosing the two parallel slits 113.1, 113.2. The base portion of the U-shaped slit 113.3 is arranged in the distal portion of the heating blade 110, whereas the branches of the U-shaped slit 113.3 extend towards, but not up to, the proximal end 111 of the blade 110. Furthermore, the heating blade 110 comprises a central longitudinal slit 113.4 extending along a length portion of the heating blade 110 from the distal end 112 towards the proximal end 111 of the heating blade 110, but not reaching said proximal end. As can be seen from fig. 6, the central longitudinal slit 113.4 extends parallel to and at least partially between the two longitudinal slits 113.1 and intersects the base portion of the U-shaped slit 113.3. As a result, the slits 113.1, 113.2, 113.3, 113.4 provide a meandering or zigzag-shaped conductor path.
According to a fourth embodiment shown in fig. 7, the heating blade 110 comprises a central longitudinal slit 113.1 extending along a length portion of the heating blade 110 from the distal end 112 towards the proximal end 111 of the heating blade 110, but not reaching said proximal end. Along the central longitudinal slit 113.1, the heating blade 110 further comprises a plurality of transverse slits 113.2 extending towards, but not reaching, the longitudinal edges of the blade 110, so as to intersect the central slit 113.1 in a transverse configuration. Furthermore, the heating blade 110 comprises a plurality of side slits 113.3 arranged along both longitudinal edges of the blade 110. The side slits 113.2 are in an offset configuration relative to the transverse slits 113.2. Each side slit 113.2 extends from the respective longitudinal edge of the blade 110 towards, but not up to, the central longitudinal slit 113.1. As a result, the slits 113.1, 113.2, 113.3, 113.4 provide a meandering or zigzag-shaped conductor path.
Fig. 8 and 9 schematically illustrate a first embodiment of a multi-layer heating element 110. The multi-layered heating element has a blade configuration having substantially the same external shape as the heating blade 110 shown in fig. 4. Accordingly, the same or similar components are denoted by the same reference numerals. Although the heating blade according to fig. 4 is essentially made of a single electrically conductive solid material or piece, the multi-layer heating blade 110 according to fig. 8 and 9 comprises two heating layers 110.1, 110.2 as edge layers and one supporting layer 110.3 sandwiched between the two heating layers 110.1, 110.2. The heating layers 110.1, 110.2 are made of an electrically conductive ferromagnetic solid material, such as permalloy. The supporting layer 110.3 is intended to increase the overall mechanical stiffness of the heating blade 110, since the ferromagnetic material may be quite ductile. In this regard, the support layer 110.3 comprises an electrically conductive solid material, for example tungsten or stainless steel, whose ductility is significantly less than the ductility of the material of the heating layers 110.1, 110.2.
When passing an AC driving current through the heating blade 110, the AC driving current is expected to flow at least partly or even mostly within the heating layers 110.1, 110.2, although the AC resistance of the support layer 110.3 may be lower than the AC resistance of the heating layers 110.1, 110.2. Therefore, heat dissipation occurs mainly within the heating layers 110.1, 110.2. The overall AC resistance of the multilayer heating element is significantly increased compared to the use of the support layer alone.
As can be seen in particular from fig. 9, which is a cross-sectional view through the conical proximal tip portion of the heating blade 110 according to fig. 8, the at least two heating layers 110.1, 110.2 have the same layer thickness and are made of the same material. Due to this, the overall arrangement of the heating blade 110 is symmetrical and thus compensates for tensile or compressive stress conditions due to possible differences in thermal expansion behaviour of the layers.
In the present exemplary embodiment, the layers 110.1, 110.2, 110.3 are connected to one another by cladding.
Fig. 10 and 11 schematically illustrate a second embodiment of a multilayer heating element 110. The heating element 110 according to this embodiment has a rod configuration, not a blade configuration. In this configuration, the multilayer heating element 110 comprises an inner core as a support layer 110.5, which is surrounded by an outer jacket as a heating layer 110.4. The heating layer 110.4 is made of an electrically conductive ferromagnetic solid material, such as permalloy. In contrast, the support layer 110.5 is made of an electrically conductive solid material, for example tungsten or stainless steel, which has a ductility that is significantly less than the ductility of the material of the heating layer 110.4. As described above in relation to fig. 8 and 9, the support layer 110.5 is intended to increase the overall mechanical stiffness of the rod-shaped heating blade 110. Also, when passing an AC drive current through the heating blade 110, the AC drive current is expected to flow at least partly or even mostly within the outer heating layer 110.4, where heat dissipation mainly occurs.
As can be seen in particular in fig. 11, which is a cross-sectional view through the rod-shaped heating element 110 according to fig. 10, the heating element 110 comprises a central longitudinal slit 113 extending along a length portion of the heating element from its distal end 112 towards its proximal end 112 to provide a U-shaped conductor path therethrough.
At its proximal end 111, the rod-shaped heating element 110 comprises a tapered tip portion allowing easy penetration of the heating rod into the aerosol-forming substrate.
