Aerosol-generating system with improved air flow control

Abstract

There is provided an aerosol-generating system including an aerosol-generating device and an aerosol-forming cartridge including at least one aerosol-forming substrate, wherein in use the aerosol-forming cartridge is at least partially received within the aerosol-generating device. The system further includes at least one electric heater configured to heat the at least one aerosol-forming substrate, at least one air inlet, and at least one air outlet. The system further includes an air flow channel extending between the at least one air inlet and the at least one air outlet. The air flow channel is in fluid communication with the aerosol-forming substrate, and has an internal wall surface on which one or more flow disturbing devices are disposed, the flow disturbing devices being arranged to create a turbulent boundary layer in a flow of air drawn through the air flow channel.

Claims

1. An electrically operated aerosol-generating system, comprising: an aerosol-generating device; an aerosol-forming cartridge comprising a base layer and at least one aerosol-forming substrate provided on the base layer, the base layer and the at least one aerosol-forming substrate being flat and being disposed parallel to each other, and the aerosol-forming cartridge being at least partially receivable within the aerosol-generating device; at least one electric heater configured to heat the at least one aerosol-forming substrate; and at least one air inlet and at least one air outlet, wherein, when the aerosol-forming cartridge is at least partially received within the aerosol-generating device, an air flow channel extends between the at least one air inlet and the at least one air outlet, the air flow channel being in fluid communication with the at least one aerosol-forming substrate, wherein the air flow channel has an internal wall surface on which one or more flow disturbing devices are disposed, the flow disturbing devices being arranged to create a turbulent boundary layer in a flow of air drawn through the air flow channel, wherein the flow disturbing devices comprise one or more dimples or undulations on the internal wall surface, and wherein the dimples or undulations have a number average maximum depth of from 0.3 mm to 0.8 mm.

2. The electrically operated aerosol-generating system according to claim 1, wherein the dimples or undulations have a number average maximum depth of from 15 percent to 80 percent of a thickness of the air flow channel.

3. The electrically operated aerosol-generating system according to claim 1, wherein the flow disturbing devices comprise a plurality of dimples on the internal wall surface.

4. The electrically operated aerosol-generating system according to claim 3, wherein the plurality of dimples have a number average maximum diameter of from 3 mm to 6 mm.

5. The electrically operated aerosol-generating system according to claim 1, wherein the air flow channel comprises a diffuser section in which a flow area of the air flow channel is increased in a downstream direction from the air inlet to the air outlet.

6. The electrically operated aerosol-generating system according to claim 1, wherein the aerosol-forming cartridge further comprises a top cover overlying the at least one aerosol-forming substrate and secured to the base layer, such that the air flow channel is at least partially defined between the top cover and the base layer, and such that the at least one aerosol-generating substrate is in fluid communication with the air flow channel.

7. The electrically operated aerosol-generating system according to claim 6, wherein the internal wall surface on which the one or more flow disturbing devices are disposed is at least partially formed by the top cover.

8. The electrically operated aerosol-generating system according to claim 1, wherein the aerosol-generating device comprises a wall overlying the at least one aerosol-forming substrate and the base layer, such that the air flow channel is at least partially defined between the wall and the base layer, and such that the at least one aerosol-generating substrate is in fluid communication with the air flow channel.

9. The electrically operated aerosol-generating system according to claim 8, wherein the internal wall surface on which the one or more flow disturbing devices are disposed is at least partially formed by the aerosol-generating device wall.

10. The electrically operated aerosol-generating system according to claim 1, wherein the flow disturbing devices occupy from 30% to 100% of an internal wall surface area.

11. The electrically operated aerosol-generating system according to claim 1, wherein the at least one aerosol-forming substrate comprises nicotine.

12. The electrically operated aerosol-generating system according to claim 1, wherein the base layer and the at least one aerosol-forming substrate each have a thickness-to-width ratio from 1:2 to 1:20.

Description

(1) The invention will now be further described, by way of example only, with reference to the accompanying drawings in which:

(2) FIG. 1 shows an aerosol-generating system according to an embodiment of the present invention;

(3) FIG. 2 shows a vertical cross-sectional view of the aerosol-forming cartridge shown in FIG. 1; and

(4) FIG. 3 shows a horizontal cross-sectional view of the aerosol-forming cartridge along the line 1-1 in FIG. 2.

(5) FIG. 1 shows an aerosol-generating system 10 in accordance with an embodiment of the present invention. The system 10 comprises an aerosol-generating device 12, an aerosol-forming cartridge 14 and a removable mouthpiece 16. The mouthpiece 16 is configured to be removable from the aerosol-generating device 10 to allow insertion of the cartridge 14 into the device 10. After the cartridge 14 has been inserted into the device 10, the mouthpiece 16 can be reconnected to the device 10.

(6) The aerosol-forming cartridge 14 comprises an air inlet 18 and an air outlet 20, as described in more detail with reference to FIG. 2. The mouthpiece 16 comprises a mouthpiece air inlet 22 that aligns with the cartridge air inlet 18 when the mouthpiece 16 is attached to the device 10. Similarly, the mouthpiece 16 comprises a plurality of mouthpiece air outlets 24 that overlie the cartridge air outlet 20 when the mouthpiece 16 is attached to the device 10.

(7) FIG. 2, which shows a vertical cross-sectional view through the aerosol-forming cartridge 14, shows the aerosol-forming cartridge 14 in more detail. The cartridge 14 comprises a base layer 30 on which an aerosol-forming substrate 32 is positioned. An electrically conductive heating mesh 34 overlies the aerosol-forming substrate 32 and terminates at electrical contacts 36 at an upstream end of the cartridge 14. During use, the electrical contacts 36 contact a similar set of electrical contacts within the aerosol-generating device 12 so that electrical energy can be supplied from the device 12 to the electrically conductive heating mesh 34 to heat the aerosol-forming substrate 32.

(8) A top cover 38 overlies the aerosol-forming substrate 32 so that the top cover 38 and the base layer 30 substantially enclose the aerosol-forming substrate 32. The air inlet 18 and the air outlet 20 are provided in the top cover 38 so that an air flow channel 40 is defined between the top cover 38 and the base layer 30 and extends between the air inlet 18 and the air outlet 20. The aerosol-forming substrate 32 is positioned within the air flow channel 40.

(9) An internal surface of the top cover 38 forms an internal wall surface 42 of the air flow channel 40 and comprises a plurality of flow disturbing devices 44 in the form of dimples. The dimples provide a turbulent boundary layer in the flow of air 46 through the air flow channel 40 and regulate the resistance to draw through the system 10.

(10) FIG. 3 shows a horizontal cross-sectional view through the aerosol-forming cartridge 14, taken along line 1-1 in FIG. 2. FIG. 3 shows the horizontal cross-sectional profile of the air flow channel 40 formed by the top cover 38. The air flow channel 40 comprises a diffuser section 48 in which the air flow channel 40 becomes wider between the air inlet 18 and the air outlet 20. The diffuser section 48 results in a reduction of the air flow velocity from the air inlet 18 to the air outlet 20, the reduction of air flow velocity optimising the formation of aerosol droplets. For reference, the locations of the air inlet 18 and the flow disturbing devices 44 are indicated with the dashed lines.