Interdigitated cylindrical heater for use in an electrical smoking article

• US 5,530,225 A
• Filed: 11/02/1994
• Issued: 06/25/1996
• Est. Priority Date: 03/11/1991
• Status: Expired due to Fees

• Current Assignee: Philip Morris USA Incorporated (Altria Group, Inc.), Philip Morris Products SA (Philip Morris Limited)
• Original Assignee: Philip Morris USA Incorporated (Altria Group, Inc.)
• Inventors: Hajaligol, Mohammad R.
• Primary Examiner(s): Walberg, Teresa J.
• Assistant Examiner(s): Paik, Sam
• Application Number:
  US08/333,470
• Time in Patent Office: 601 Days
• Field of Search: 219/535, 219/542, 219/552-553, 131/194, 131/197, 128/202.21, 128/203.27, 338/310, 338/312, 338/320, 392/386
• US Class Current: 219/535
• CPC Class Codes: A24F 40/20 Devices using solid inhalable precursors
• CPC Class Codes: A24F 40/46 Shape or structure of electric heating means

Abstract

A heater having a generally cylindrical or tubular configuration comprised of a selected plurality of thermally conductive heater blades and adjacent heat sink and aerosol barrier blades interposed between the heater blades to form an interdigitated structure. A respective gap is defined between a heater blade and an adjacent heat sink blade to prevent heat loss during an electrical pulse which heats the heater blade. During the subsequent cooling period and puff interval, the adjacent heat sink blades prevent heat from propagating to other parts of the aerosol generating tube, i.e., the cigarette. In addition to the thermal function, the barrier blades also block the escape of moisture generated by the aerosol generating medium, thereby limiting the propagation of condensation. The respective gaps between the interdigitated blades are defined to be wide enough to prevent heat losses during pulsing from a heater blade to adjacent blades yet small enough to prevent escape of significant amounts of vapor.

Claims

1. A heater for use in a smoking article having a source of electrical energy for heating a cigarette, said heater comprising:

a plurality of heater elements electrically connected to the source of electrical energy to be heated thereby; and

a plurality of barrier blades;

wherein said plurality of heater elements and said plurality of barrier blades are located adjacent one another in a thermally isolated alternating and interdigitated arrangement and define a cylindrical receptacle to receive the cigarette upon insertion for heating by said plurality of heater elements, said plurality of barrier blades reducing escape from the defined cylindrical receptacle of vapors generated by said plurality of heater elements heating selected portions of the cigarette.

2. The heater according to claim 1, further comprising a plurality of heater blades, each heater blade having a respective heater element fixed thereto.

3. The heater according to claim 2, wherein said plurality of heater elements are each respectively located on an outer side of a respective heater blade opposite an inner side of the heater blade facing the inserted cigarette.

4. The heater according to claim 2, wherein there are eight heater blades and eight barrier blades.

5. The heater according to claim 2, wherein said barrier blades comprise a thermally insulating material.

6. The heater according to claim 2, further comprising a supporting hub, each of said plurality of said heater blades extending longitudinally from said supporting hub in a particular same direction.

7. The heater according to claim 6, wherein each of the plurality of said barrier blades extend longitudinally from said supporting hub in the particular direction.

8. The heater according to claim 2, wherein said plurality of heating of heater blades and said barrier blades are arranged to define a longitudinally extending gap between each adjacent barrier blade and heater element.

9. The heater according to claim 8, wherein the defined gaps are less than or equal to approximately 15 mil. wide.

10. The heater according to claim 8, wherein the defined gaps are approximately 5 mil. wide.

11. The heater according to claim 8, wherein the defined gaps are approximately 5 mil, wide.

12. The heater according to claim 1, wherein there are eight heater elements and eight barrier blades.

13. The heater according to claim 1, wherein said barrier blades comprise a thermally insulating material.

14. The heater according to claim 1, further comprising a supporting hub, each of said plurality of barrier blades extending longitudinally from said supporting hub in a particular direction.

15. The heater according to claim 1, wherein said plurality of heater elements and said plurality of barrier blades are arranged to define a longitudinally extending gap between each adjacent blade and heater element.

16. The heater according to claim 15, wherein the defined gaps are less than or equal to approximately 15 mil. wide.

17. The heater according to claim 15, wherein the defined gaps are approximately 15-5 mil. wide.

18. The heater according to claim 15, wherein the defined gaps are approximately 5 mil. wide.

19. The heater according to claim 2, wherein said heater blades comprise an electrically insulating substrate, and said heater element comprises an electrically resistive layer deposited on the electrically insulating substrate, said electrically resistive layer electrically connected to the source of electrical energy and heated thereby.

20. The heater according to claim 19, wherein said substrate faces the inserted cylindrical cigarette.

21. The heater according to claim 19, further comprising a heater blade hub connected to a respective end of each of the plurality of said heater blades and further comprising a barrier blade hub connected to a respective end of each of the plurality of said barrier blades, wherein said barrier blade hub is located at an opposite end of the formed cylindrical configuration from said heater blade hub.

22. The heater according to claim 19, wherein said heater blades comprise a ceramic.

23. The heater according to claim 22, wherein said ceramic comprises zirconia.

24. The heater according to claim 22, wherein said ceramic comprises alumina.

25. The heater according to claim 2, further comprising a heater blade hub connected to a respective end of each of the plurality of said heater blades and further comprising a barrier blade hub connected to a respective end of each of the plurality of said barrier blades, wherein said barrier blade hub is located at an opposite end of the formed cylindrical configuration from said heater blade hub.

26. The heater according to claim 1, further comprising first and second oppositely located end hubs, said plurality of barrier blades extending longitudinally from said first hub to said second hub.

27. The heater according to claim 26, wherein said plurality of longitudinally extending barrier blades define a plurality longitudinally extending spaces bounded by successive blades and said first and second hubs, wherein each heater element is inserted into a respective defined space.

28. The heater according to claim 27, further comprising a connecting heater hub overlying the first hub and connected to each of the inserted heater elements.

29. The heater according to claim 28, wherein each of said heater elements comprises a respective positive contact pad electrically connected to a first end of each heater element, said positive contact pad electrically connected to a positive connection of the source of electrical energy.

30. The heater according to claim 27, wherein the heater blades are bowed inwardly.

31. The heater according to claim 2, further comprising first and second opposite end hubs, wherein said plurality of barrier blades extend longitudinally from the first end hub in a particular direction and said plurality of heater blades extend longitudinally from the second end hub in an opposite direction, wherein gaps are respectively defined between adjacent heater and barrier blades.

32. The heater according to claim 31, wherein gaps are defined between the second end hub and an end of each barrier blade opposite the first end hub, and wherein gaps are defined between the first end hub and an end of each heater blade opposite the second end hub.

33. The heater according to claim 31, wherein said heater blades and said barrier blades are integrally formed at opposite ends to said first and second opposite end hubs.

34. The heater according to claim 31, wherein said plurality of barrier blades is connected at a first end to the first end hub and at a second end hub to the second end hub.

35. The heater according to claim 34, further comprising a common ring electrically connected to a second end of each heater element, said common ring electrically connected to a negative connection of the source of electrical energy, the first end of each heater element located opposite said second end hub.

36. The heater according to claim 35, further comprising a layer of contact material extending from a second end of each heater element, the second end of each heater element located at said second end hub.

37. The heater according to claim 36, wherein said layer of contact material further extends around said second end hub to define a common.

38. The heater according to claim 36, wherein said layer of contact material extends from each second end of each heater element, along an adjacent barrier blade, and around said first end hub to define a common.

39. The heater according to claim 34, further comprising a layer of contact material extending from a second end of each heater element, the second end of each heater element located at said second end hub.

40. The heater according to claim 39, wherein said layer of contact material further extends around said second end hub to define a common.

41. The heater according to claim 39, wherein said layer of contact material extends from each second end of each heater element, along an adjacent barrier blade, and around said first end hub to define a common.

42. The heater according to claim 1, wherein the heater elements are bowed inwardly.

43. The heater according to claim 1, wherein each of said heater elements comprises a respective positive contact pad electrically connected to a first end of each heater element, said positive contact pad electrically connected to a positive connection of the source of electrical energy.

44. The heater according to claim 43, wherein each of said heater elements further comprises a respective negative contact pad electrically connected to a second end of each heater element, said negative contact pad electrically connected to a negative connection of the source of electrical energy.

45. The heater according to claim 43, further comprising a common ring electrically connected to a second end of each heater element, said common ring electrically connected to a negative connection of the source of electrical energy.

46. The heater according to claim 2, wherein said plurality of heater blades and barrier blades define an insertion opening for the cigarette, the insertion opening narrowing to the defined cylindrical receptacle.

47. The heater according to claim 46, wherein the insertion opening has a larger diameter than the inserted cigarette.

48. The heater according to claim 2, wherein said heater blades and said barrier blades have approximately equal widths.

49. The heater according to claim 2, further comprising another plurality of heater elements, each of said other plurality of heater elements respectively fixed to each of said barrier blades.