Apparatus for a resonance circuit

Patent metadata

Field	Value
Publication number	US-11765795-B2
Application number	US-201816497597-A
Country	US
Kind code	B2
Filing date	Mar 27, 2018
Priority date	Mar 31, 2017
Publication date	Sep 19, 2023
Grant date	Sep 19, 2023

Abstract

Disclosed is a method and apparatus for use with an RLC resonance circuit for inductive heating of a susceptor of an aerosol generating device. The apparatus is arranged to determine a resonant frequency of the RLC resonance circuit; and determine, based on the determined resonant frequency, a first frequency for the RLC resonance circuit for causing the susceptor to be inductively heated, the first frequency being above or below the determined resonant frequency. The apparatus may be arranged to control a drive frequency of the RLC resonance circuit to be at the determined first frequency in order to heat the susceptor. Also disclosed is an aerosol generating device including the apparatus.

First claim

The invention claimed is:

1. An aerosol generating device comprising:
a RLC resonance circuit for inductive heating of a susceptor of the aerosol generating device; and
a controller, said controller being arranged to:
determine a resonant frequency of the RLC resonance circuit; and
determine, based on the determined resonant frequency, a first frequency for the RLC resonance circuit for causing the susceptor to be inductively heated, the first frequency being above or below the determined resonant frequency; and
control a drive frequency of the RLC resonance circuit to be at the determined first frequency in order to heat the susceptor.

2. The aerosol generating device according to claim 1 , wherein the first frequency is for causing the susceptor to be inductively heated to a first degree at a given supply voltage, the first degree being less than a second degree, the second degree being a degree to which the susceptor is caused to be inductively heated, at the given supply voltage, when the RLC circuit is driven at the resonant frequency.

3. The aerosol generating device according to claim 1 , wherein the controller is further arranged to control the drive frequency to be held at the first frequency for a first period of time.

4. The aerosol generating device according to claim 1 , wherein the controller is further arranged to control the drive frequency to be at one of a plurality of first frequencies each different from one another.

5. The aerosol generating device according to claim 4 , wherein the controller is further arranged to control the drive frequency through the plurality of first frequencies in accordance with a sequence.

6. The aerosol generating device according claim 5 , wherein the controller is further arranged to select the sequence from one of a plurality of predefined sequences.

7. The aerosol generating device according to claim 5 , wherein the controller is further arranged to:
control the drive frequency such that each of the first frequencies in the sequence is closer to the resonant frequency than the previous first frequency in the sequence, or
control the drive frequency such that each of the first frequencies in the sequence is further from the resonant frequency than the previous first frequency in the sequence.

8. The aerosol generating device according to claim 4 , wherein the controller is further arranged to control the drive frequency to be held at one or more of the plurality of first frequencies for a respective one or more time periods.

9. The aerosol generating device according to claim 1 , wherein the controller is further arranged to:
measure an electrical property of the RLC circuit as a function of the drive frequency; and
determine the resonant frequency of the RLC circuit based on the measured electrical property.

10. The aerosol generating device according to claim 9 , wherein the controller is further arranged to determine the first frequency based on the measured electrical property of the RLC circuit as a function of the drive frequency at which the RLC circuit is driven.

11. The aerosol generating device according to claim 9 , wherein the electrical property is a voltage measured across an inductor of the RLC circuit, the inductor being for energy transfer to the susceptor.

12. The aerosol generating device according to claim 9 , wherein the measurement of the electrical property is a passive measurement.

13. The aerosol generating device according to claim 12 , wherein the electrical property is indicative of a current induced in a sense coil, the sense coil being for energy transfer from an inductor of the RLC circuit, the inductor being for energy transfer to the susceptor.

14. The aerosol generating device to claim 12 , wherein the electrical property is indicative of a current induced in a pick-up coil, the pick-up coil being for energy transfer from a supply voltage element, the supply voltage element being for supplying voltage to a driving element, the driving element being for driving the RLC circuit.

15. The aerosol generating device according to claim 1 , wherein the controller is further arranged to determine at least one of the resonant frequency of the RLC circuit or the first frequency substantially on start-up of the aerosol generating device, or substantially on installation of a new or replacement susceptor into the aerosol generating device, or substantially on installation of a new or replacement inductor into the aerosol generating device.

16. The aerosol generating device according to claim 1 , wherein the controller is further arranged to:
determine a characteristic indicative of a bandwidth of a peak of a response of the RLC circuit, the peak corresponding to the resonant frequency; and
determine the first frequency based on the determined characteristic.

17. The aerosol generating device according to claim 1 , wherein the apparatus comprises:
a driving element arranged to drive the RLC resonance circuit at one or more of a plurality of frequencies, wherein the apparatus is arranged to control the driving element to drive the RLC resonant circuit at the determined first frequency.

18. The aerosol generating device according to claim 17 , wherein the driving element comprises a H-Bridge driver.

19. The aerosol generating device according to claim 1 , further comprising the RLC resonance circuit.

20. The aerosol generating device according to claim 1 , wherein the susceptor comprises one or more of nickel or steel.

21. The aerosol generating device according to claim 20 , wherein the susceptor comprises a body having a nickel coating.

22. The aerosol generating device according to claim 21 , wherein the nickel coating has a thickness less than substantially 5 μm.

23. The aerosol generating device according to claim 21 , wherein the nickel coating is electroplated on to the body.

24. The aerosol generating device according to claim 20 , wherein the susceptor comprises a sheet of mild steel.

25. The aerosol generating device according to claim 24 , wherein the sheet of mild steel has a thickness in the range of substantially 10 μm to substantially 50 μm.

26. A method of operating an aerosol generating device comprising an RLC resonance circuit for inductive heating of a susceptor of the aerosol generating device and a controller, the method comprising:
determining a resonant frequency of the RLC resonance circuit;
determining a first frequency for the RLC resonance circuit for causing the susceptor to be inductively heated, the first frequency being above or below the determined resonant frequency; and
controlling a drive frequency of the RLC resonance circuit to be at the determined first frequency in order to heat the susceptor.

27. A non-transitory computer-readable storage medium storing a computer program which, when executed on a processing system, causes the processing system to perform the method of claim 26 .

Assignees

• British American Tobacco Investments Ltd
• Nicoventures Trading Ltd

Inventors

• Abi Aoun Walid
• Fallon Gary
• White Julian Darryn
• Horrod Martin Daniel

Classifications

• H05B6/06 Primary

  Control, e.g. of temperature, of power · CPC title

• A24F40/465 Primary

  specially adapted for induction heating · CPC title

• H05B6/105

  using a susceptor · CPC title

• A24F40/50

  Control or monitoring · CPC title

• A24F40/20

  Devices using solid inhalable precursors · CPC title