AN INDUCTIVE HEATING ARRANGEMENT HAVING AN ANNULAR CHANNEL

Abstract

An inductive heating arrangement is provided, including: a first inductor coil to generate a first varying magnetic field when a varying electric current flows through the first coil; a second inductor coil to generate a second varying magnetic field when a varying electric current flows through the second coil; and a tubular-shaped flux concentrator around the first coil and to distort the first field, including a main portion around the first coil and having an inner diameter, first and second ends, a first end portion having an inner diameter smaller than that of the main portion, and a second end portion having an inner diameter smaller than that of the main portion, an inner surface of the flux concentrator defining an annular channel between the first and second end portions, and the first inductor coil being disposed within the annular channel between the first and second end portions.

Claims

1.-13. (canceled)

14. An inductive heating arrangement, comprising: a first inductor coil configured to generate a first varying magnetic field when a varying electric current flows through the first inductor coil; a second inductor coil configured to generate a second varying magnetic field when a varying electric current flows through the second inductor coil; and a flux concentrator disposed around the first inductor coil and configured to distort the first varying magnetic field generated by the first inductor coil, wherein the flux concentrator has a tubular shape and comprises: a main portion disposed around the first inductor coil, the main portion having an inner diameter, a first end, and a second end, a first end portion at the first end of the main portion, the first end portion having an inner diameter, wherein the inner diameter of the first end portion is smaller than the inner diameter of the main portion, and a second end portion at the second end of the main portion, the second end portion having an inner diameter, wherein the inner diameter of the second end portion is smaller than the inner diameter of the main portion, wherein an inner surface of the flux concentrator defines an annular channel between the first end portion and the second end portion, and wherein the first inductor coil is disposed within the annular channel between the first end portion and the second end portion.

15. The inductive heating arrangement according to claim 14, wherein the flux concentrator is a first flux concentrator, wherein the main portion is a first main portion disposed around the first inductor coil, wherein the annular channel is a first annular channel, wherein the inductive heating arrangement comprises a second flux concentrator disposed around the second inductor coil to distort the second varying magnetic field generated by the second inductor coil, and wherein the second flux concentrator has a tubular shape and comprises: a second main portion disposed around the second inductor coil, the second main portion having an inner diameter, a first end, and a second end, a third end portion at the first end of the second main portion, the third end portion having an inner diameter, wherein the inner diameter of the third end portion is smaller than the inner diameter of the second main portion, and a fourth end portion at the second end of the second main portion, the fourth end portion having an inner diameter, wherein the inner diameter of the fourth end portion is smaller than the inner diameter of the second main portion, wherein an inner surface of the second flux concentrator defines a second annular channel between the third end portion and the fourth end portion, and wherein the second inductor coil is disposed within the second annular channel between the third end portion and the fourth end portion.

16. The inductive heating arrangement according to claim 14, wherein the flux concentrator is disposed around the first inductor coil and the second inductor coil to distort the first and second varying magnetic fields generated by the first and second inductor coils, wherein the main portion is a first main portion disposed around the first inductor coil, wherein the annular channel is a first annular channel, wherein the flux concentrator further comprises: a second main portion disposed around the second inductor coil, the second main portion having an inner diameter, a first end, and a second end, and a third end portion at the first end of the second main portion, the third end portion having an inner diameter, wherein the inner diameter of the third end portion is smaller than the inner diameter of the second main portion, wherein the second end portion is at the second end of the second main portion so that the second end portion is disposed between the first main portion and the second main portion, wherein the inner diameter of the second end portion is smaller than the inner diameter of the second main portion, wherein the inner surface of the flux concentrator defines a second annular channel between the second end portion and the third end portion, and wherein the second inductor coil is disposed within the second annular channel between the second end portion and the third end portion.

17. The inductive heating arrangement according to claim 14, wherein each inductor coil and each respective annular channel are disposed concentrically about a longitudinal axis, and wherein a cross-sectional shape of each annular channel in a longitudinal direction along the longitudinal axis is U-shaped.

18. The inductive heating arrangement according to claim 17, wherein the U-shaped cross-sectional shape of each annular channel is a rectangular U-shaped cross-sectional shape.

19. The inductive heating arrangement according to claim 14, wherein each inductor coil and each respective annular channel are disposed concentrically about a longitudinal axis, wherein each flux concentrator is formed from a discrete first part having a semi-annular shape and a discrete second part having a semi-annular shape, and wherein the first part and the second part together define the tubular shape of the flux concentrator.

20. The inductive heating arrangement according to claim 14, wherein each flux concentrator comprises a plurality of discrete annular segments disposed consecutively to define the tubular shape of the flux concentrator.

21. The inductive heating arrangement according to claim 20, further comprising: a first discrete annular segment defining the first end portion of the flux concentrator; a second discrete annular segment defining the second end portion of the flux concentrator; and at least one intermediate discrete annular segment defining the main portion of the flux concentrator.

22. The inductive heating arrangement according to claim 15, wherein each flux concentrator comprises a plurality of discrete annular segments disposed consecutively to define the tubular shape of the flux concentrator, the inductive heating arrangement further comprising: a first discrete annular segment defining the first end portion of the flux concentrator; a second discrete annular segment defining the second end portion of the flux concentrator; a third discrete annular segment defining the third end portion of the second flux concentrator; a fourth discrete annular segment defining the fourth end portion of the second flux concentrator; at least one first intermediate discrete annular segment defining the first main portion of the first flux concentrator; and at least one second intermediate discrete annular segment defining the second main portion of the second flux concentrator.

23. The inductive heating arrangement according to claim 16, wherein each flux concentrator comprises a plurality of discrete annular segments disposed consecutively to define the tubular shape of the flux concentrator, the inductive heating arrangement further comprising: a first discrete annular segment defining the first end portion of the flux concentrator; a second discrete annular segment defining the second end portion of the flux concentrator; a third discrete annular segment defining the third end portion of the flux concentrator; and at least one intermediate discrete annular segment defining the main portion of the flux concentrator; wherein the at least one intermediate discrete annular segment defining the main portion of the flux concentrator comprises at least one first intermediate discrete annular segment defining the first main portion and at least one second intermediate discrete annular segment defining the second main portion.

24. The inductive heating arrangement according to claim 14, wherein each flux concentrator comprises a material having a relative magnetic permeability of at least 5 at a frequency of between 6 megahertz and 8 megahertz and a temperature of 25 degrees Celsius.

25. The inductive heating arrangement according to claim 14, wherein each flux concentrator comprises a ferromagnetic material.

26. An aerosol-generating device, comprising: an inductive heating arrangement according to claim 14; a power supply; and a controller configured to supply a varying electric current from the power supply to each inductor coil.

Description

[0108] Embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0109] FIG. 1 shows a longitudinal cross-sectional view of an inductive heating arrangement according to a first embodiment of the present disclosure;

[0110] FIG. 2 shows a partially exploded transverse cross-sectional view of the inductive heating arrangement of FIG. 1 along line 1-1;

[0111] FIG. 3 shows a cross-sectional view of an aerosol-generating system comprising an aerosol-generating article and an aerosol-generating device comprising the inductive heating arrangement of FIG. 1;

[0112] FIG. 4 shows the aerosol-generating system of FIG. 3 with the aerosol-generating article received within the aerosol-generating device;

[0113] FIG. 5 shows a longitudinal cross-sectional view of an inductive heating arrangement according to a second embodiment of the present disclosure; and

[0114] FIG. 6 shows a longitudinal cross-sectional view of an inductive heating arrangement according to a third embodiment of the present disclosure.

[0115] FIG. 1 shows a longitudinal cross-sectional view of an inductive heating arrangement 10 according to a first embodiment of the present disclosure. The inductive heating arrangement 10 comprises a first inductor coil 12 and a second inductor coil 14 positioned coaxially around a tubular susceptor 16 along a longitudinal axis 18 of the inductive heating arrangement 10. The susceptor 16 defines a cavity 19 in which an aerosol-forming substrate may be received for heating by the inductive heating arrangement 10.

[0116] The inductive heating arrangement 10 comprises a first flux concentrator 20 positioned around the first inductor coil 12 and a second flux concentrator 22 positioned around the second inductor coil 14. The first and second flux concentrators 20, 22 are each formed from a ferromagnetic material.

[0117] The first flux concentrator 20 has a tubular shape and comprises a first main portion 24 positioned around the first inductor coil 12, a first end portion 26 at a first end of the first main portion 24, and a second end portion 28 at a second end of the first main portion 24. The first and second end portions 26, 28 each have an inner diameter that is smaller than an inner diameter of the first main portion 24. An inner surface 30 of the first flux concentrator 20 defines a first annular channel 32 between the first end portion 26 and the second end portion 28. The first inductor coil 12 is positioned within the first annular channel 32 between the first end portion 26 and the second end portion 28.

[0118] The second flux concentrator 22 has a tubular shape and comprises a second main portion 34 positioned around the second inductor coil 14, a third end portion 36 at a first end of the second main portion 34, and a fourth end portion 38 at a second end of the second main portion 34. The third and fourth end portions 36, 38 each have an inner diameter that is smaller than an inner diameter of the second main portion 34. An inner surface 40 of the second flux concentrator 22 defines a second annular channel 42 between the third end portion 36 and the fourth end portion 38. The second inductor coil 14 is positioned within the second annular channel 42 between the third end portion 36 and the fourth end portion 38.

[0119] When a varying electric current is supplied to the first inductor coil 12, the first inductor coil 12 generates a varying magnetic field. The shape of the first flux concentrator 20, and in particular the first and second end portions 26, 28, distort the varying magnetic field so that the varying magnetic field is concentrated in a first portion of the susceptor 16 positioned within the first inductor coil 12. The varying magnetic field generated by the first inductor coil 12 induces eddy currents in the first portion of the susceptor 16, causing the first portion of the susceptor 16 to be heated. Advantageously, the concentration of the varying magnetic field in the first portion of the susceptor 16 by the first flux concentrator 20 reduces or minimises heating of a second portion of the susceptor 16 positioned within the second inductor coil 14 by the varying magnetic field generated by the first inductor coil 12.

[0120] When a varying electric current is supplied to the second inductor coil 14, the second inductor coil 14 generates a varying magnetic field. The shape of the second flux concentrator 22, and in particular the first and second end portions 36, 38, distort the varying magnetic field so that the varying magnetic field is concentrated in the second portion of the susceptor 16 positioned within the second inductor coil 14. The varying magnetic field generated by the second inductor coil 14 induces eddy currents in the second portion of the susceptor 16, causing the second portion of the susceptor 16 to be heated. Advantageously, the concentration of the varying magnetic field in the second portion of the susceptor 16 by the second flux concentrator 22 reduces or minimises heating of the first portion of the susceptor 16 positioned within the first inductor coil 12 by the varying magnetic field generated by the second inductor coil 14.

[0121] FIG. 2 shows a partially exploded transverse cross-sectional view of the inductive heating arrangement 10 of FIG. 1 along line 1-1. The first flux concentrator 20 comprises a discrete first part 44 having a semi-annular shape and a discrete second part 46 having a semi-annular shape. When the discrete first and second parts 44, 46 are brought together they define the tubular shape of the first flux concentrator 20. Advantageously, forming the first flux concentrator 20 from first and second parts 44, 46 each having a semi-annular shape facilitates assembly of the inductive heating assembly 10. For example, as shown in FIG. 2, the first inductor coil 12 may be positioned over the first portion of the susceptor 16. The first and second parts 44, 46 may then be positioned around the first inductor coil 12 and brought into contact with each other to form the first flux concentrator 20. The same arrangement can be used to assembly the second flux concentrator 22. In other words, the second flux concentrator 22 may also be formed from discrete first and second parts each having a semi-annular shape.

[0122] FIG. 3 shows a cross-sectional view of an aerosol-generating system 100 according to an embodiment of the present disclosure. The aerosol-generating system 100 comprises an aerosol-generating device 102 comprising the inductive heating arrangement 10 of FIG. 1. The aerosol-generating system 100 also comprises an aerosol-generating article 200.

[0123] The aerosol-generating device 102 comprises a substantially cylindrical device housing 103, with a shape and size similar to a conventional cigar. The device housing 103 defines a device cavity 104 at a proximal end. The device cavity 104 is substantially cylindrical, open at a proximal end, and substantially closed at a distal end, opposite the proximal end. The device cavity 104 is configured to receive a portion of the aerosol-generating article 200. Accordingly, the diameter of the device cavity 104 is substantially similar to the diameter of the aerosol-generating article 200.

[0124] The aerosol-generating device 102 further comprises a power supply 106, in the form of a rechargeable nickel-cadmium battery, a controller 108 in the form of a printed circuit board including a microprocessor, an electrical connector 109, and the inductive heating arrangement 10. The power supply 106, controller 108 and inductive heating arrangement 10 are all housed within the device housing 103. The inductive heating arrangement 10 of the aerosol-generating device 102 is arranged at the proximal end of the device 102, and is generally disposed around the device cavity 104. The electrical connector 109 is arranged at a distal end of the device housing 103, opposite the device cavity 104.

[0125] The controller 108 is configured to control the supply of power from the power supply 106 to the inductive heating arrangement 10. The controller 108 further comprises a DC/AC inverter, including a Class-D power amplifier, and is configured to supply at least one varying electric current to the inductive heating arrangement 10. The controller 108 is also configured to control recharging of the power supply 106 from the electrical connector 109. In addition, the controller 108 comprises a puff sensor (not shown) configured to sense when a user is drawing on an aerosol-generating article received in the device cavity 104.

[0126] The first inductor coil 12 is connected to the controller 108 and the power supply 106, and the controller 108 is configured to supply a varying electric current to the first inductor coil 12. When a varying electric current is supplied to the first inductor coil 12, the first inductor coil 12 generates a varying magnetic field, which heats the first portion of the susceptor 16 by induction.

[0127] The second inductor coil 14 is connected to the controller 108 and the power supply 106, and the controller 108 is configured to supply a varying electric current to the second inductor coil 14. When a varying electric current is supplied to the second inductor coil 14, the second inductor coil 14 generates a varying magnetic field, which heats the second portion of the susceptor 16 by induction.

[0128] The device housing 103 also defines an air inlet 180 in close proximity to the distal end of the device cavity 106. The air inlet 180 is configured to enable ambient air to be drawn into the device housing 103. An airflow pathway is defined through the device, between the air inlet 180 and an air outlet in the distal end of the device cavity 104, to enable air to be drawn from the air inlet 180 into the device cavity 104.

[0129] The aerosol-generating article 200 comprises an aerosol-forming substrate 202 in the form of a cylindrical rod and comprising tobacco. The cylindrical rod of aerosol-forming substrate 202 has a length substantially equal to the length of the device cavity 104. The aerosol-generating article 200 also comprises a tubular cooling segment 204, a filter segment 206, and a mouth end segment 208. The aerosol-forming substrate 202, the tubular cooling segment 204, the filter segment 206 and the mouth end segment 208 are held together by an outer wrapper 210.

[0130] As shown in FIG. 4, when the aerosol-forming substrate 202 of the aerosol-generating article 200 is received in the device cavity 104, the length of the aerosol-forming substrate 202 is such that the aerosol-forming substrate 202 extends along the length of the inductive heating arrangement 10.

[0131] In use, when an aerosol-generating article 200 is received in the device cavity 104, a user may draw on the proximal end of the aerosol-generating article 200 to inhale aerosol generated by the aerosol-generating system 100. When a user draws on the proximal end of the aerosol-generating article 200, air is drawn into the device housing 103 at the air inlet 180, and is drawn along the airflow pathway, into the device cavity 104. The air is drawn into the aerosol-generating article 200 at the proximal end of the aerosol-forming substrate 202 through the outlet in the distal end of the device cavity 104.

[0132] The controller 108 of the aerosol-generating device 102 is configured to supply power to the first and second inductor coils 12, 14 of the inductive heating arrangement 10 according to a predetermined heating profile during. The predetermined heating profile comprises supplying a varying electric current to the first inductor coil 12 to heat the first portion of the susceptor 16 to an operating temperature for a first time period. The predetermined heating profile also comprises supply a varying electric current to the second inductor coil 14 to heat the second portion of the susceptor 16 to an operating temperature for a second time period. In this embodiment, the first time period and the second time period partially overlap. In other words, the second time period begins when part of the first time period has elapsed, and the first time period ends when part of the second time period has elapsed. However, it will be appreciated that the controller 108 may be configured to supply power to the first and second inductor coils 12, 14 according to a different heating profile, depending on the desired delivery of aerosol to the user. In some embodiments, the aerosol-generating device 102 may be controllable by a user to change the heating profile.

[0133] FIG. 5 shows a longitudinal cross-sectional view of an inductive heating arrangement 310 according to a second embodiment of the present disclosure. The inductive heating arrangement 310 shown in FIG. 5 is similar to the inductive heating arrangement 10 of FIG. 1 and like reference numerals are used to designate like parts.

[0134] The inductive heating arrangement 310 comprises a single flux concentrator 313 having a tubular shape and comprising the first main portion 24 positioned around the first inductor coil 12, the second main portion 34 positioned around the second inductor coil 14, the first end portion 26 at a first end of the first main portion 24, the second end portion 28 at the second ends of the first and second main portions 24, 34, and the third end portion 36 at the first end of the second main portion 34. The inner surface 331 of the flux concentrator 313 defines the first annular channel 32 between the first end portion 26 and the second end portion 28, and the second annular channel 42 between the second end portion 28 and the third end portion 36. Preferably, the flux concentrator 313 comprises discrete first and second portions each having a semi-annular shape as described with reference to FIG. 2 for the inductive heating arrangement 10.

[0135] FIG. 6 shows a longitudinal cross-sectional view of an inductive heating arrangement 410 according to a third embodiment of the present disclosure. The inductive heating arrangement 410 shown in FIG. 6 is similar to the inductive heating arrangement 310 of FIG. 5 and like reference numerals are used to designate like parts.

[0136] The inductive heating arrangement 410 comprises a single flux concentrator 413 comprising a plurality of discrete annular segments 411 positioned consecutively to define the tubular shape of the flux concentrator 413. The plurality of discrete annular segments 411 comprises a first discrete annular segment 427 defining the first end portion 26 of the flux concentrator 413, a second discrete annular segment 429 defining the second end portion 28 of the flux concentrator 413, and a third discrete annular segment 437 defining the third end portion 36 of the flux concentrator 413. The plurality of discrete annular segments 411 also comprises a plurality of first intermediate discrete annular segments 425 defining the first main portion 24 of the flux concentrator 413, and a plurality of second intermediate discrete annular segments 435 defining the second main portion 34 of the flux concentrator 413.

[0137] It will be appreciated that the first and second flux concentrators 20, 22 of the inductive heating arrangement 10 of FIG. 1 may each be formed from a plurality of discrete annular segments in the same manner as the flux concentrator 413 of FIG. 6.