Aerosol dilution for automatic smoking machine

Abstract

 The present invention relates to an aerosol dilution device for automatic smoking machines, comprising a first channel for an aerosol and a second channel for a dilution gas, in particular air. The first channel and the second channel both release their downstream ends in a third channel, wherein the second channel is arranged around the first channel at the upstream side of the third channel. The invention further relates to a method for diluting a stream of aerosol, in particular provided by a smoking article, with a stream of dilution gas, in particular air, wherein the stream of dilution gas forms a sheath in between a wall of a diluting section and the stream of the aerosol when the streams are joined.

Description

[0001] The present invention relates to an aerosol dilution device for automatic smoking machines, wherein an aerosol is diluted by a dilution gas, in particular air. The invention further relates to a method for diluting a stream of aerosol with a stream of dilution gas, in particular air.

[0002] In the prior art, it is known to analyze the aerosol provided by smoking articles by means of smoking machines. These smoking machines have a defined amount of aerosol drawn from smoking articles on a time scale, otherwise known as the puff profile. The puff profile allows for analyzing the contents of the aerosol provided by a smoking article in a standardized manner.

[0003] US 2010/0273246 A1 relates to such a smoking apparatus, which further comprises a diluting section, wherein a clean air supply section provides air to a concentration setting section to adjust the concentration of the smoke by means of dilution. Several dilutions of the aerosol may take place in different sections of the apparatus.

[0004] Currently, new types of smoking articles are developed, which provide a different smoking experience. These types of smoking articles heat a substrate, which produces an aerosol to be inhaled by a consumer. The substrate can be in solid or liquid form comprising a inhalable substance to be vaporized, or in the form of tobacco which is heated but not burned. The heating of the substrate may be accomplished through an electrical heating source, a gas burner or by other energy sources where the effect is to heat, not burn, the substrate.

[0005] For the new types of smoking articles, as for any other smoking articles, a reliable and reproducible testing environment has to be provided for inhalation studies on biological systems. The aerosol is exposed to in-vivo and in-vitro test systems with reproducible concentrations of the aerosol. Therefore, a reproducible aerosol generation system, and a preferably loss-free transportation of the aerosol to biological systems, such as cell cultures, is needed.

[0006] For a conventional cigarette, the aerosol consists mainly of components with a high boiling temperature, and nucleation and condensation is usually completed in the cigarette. Thus, the aerosol leaving the mouth piece of the cigarette is thermodynamically in equilibrium with its environment. Only components of high vapor pressure, such as aldehydes or similar, could evaporate after the dilution with fresh air. This thermodynamic equilibrium of the aerosol does not impact the smoking machine by leaving condensate after the aerosol leaves the mounthpiece of the smoking article. However, for new types of smoking articles as described above, with aerosols generated primarily by heating evaporable material, the aerosol commonly leaves the mouth piece of the smoking article not completely condensed, and with a temperature higher than the ambient temperature. Thus, the gas phase components of the aerosol tend to condensate on surfaces of the aerosol path downstream of the mouth piece in the smoking machine.

[0007] Furthermore, density and particle size found in the aerosols of the new types of smoking articles can be larger than what is found in conventional cigarette smoke. Larger particles are adsorbed by the surfaces of the aerosol path in smoking machines with a much higher probability than smaller ones.

[0008] It is the object of the invention to provide an aerosol dilution device, and a method for diluting a stream of aerosol, which prevents the loss of liquid or solid particles of the aerosol.

[0009] The object of the invention is attained by an aerosol dilution device for automatic smoking machines comprising a first channel for an aerosol and a second channel for a dilution gas, in particular air, wherein the first channel and the second channel both release their downstream ends into a third channel, and the second channel is arranged around the first channel at the upstream side of the third channel. In particular, the first channel and the second channel terminate at their downstream ends in a third channel. Thus, as the dilution gas is provided around the aerosol as it enters the third channel, contact of the liquid or solid particles of the aerosol with a wall of the third channel is prevented. This enables that a dilution can be carried out before aerosol particles are lost.

[0010] In particular, the third channel is arranged very close to the smoking article, an indication that the length of the first channel is small. The dilution would therefore take place immediately downstream of the smoking article, preventing loss of aerosol particles.

[0011] Aerosol particles can be lost due to condensation, diffusion or impaction on the walls of the channel of a smoking machine or dilution device. However, with the inventive aerosol dilution device, the loss of aerosol particles can be significantly reduced or prevented. In particular, the dilution gas provided by the second channel forms a sheath of dilution gas in between the aerosol provided by the first channel and the wall of the third channel. Not yet condensed components of the aerosol have the opportunity to nucleate or to contribute to the growing of already formed particles during dilution, while not coming into contact with the wall of the third channel.

[0012] Preferably, the aerosol dilution device is adapted to establish at the upstream side of the third channel a flow of the dilution gas of the second channel at substantially the same speed as the flow of the aerosol of the first channel. Thus, the flows of dilution gas and aerosol in the third channel are isokinetic. No turbulences or significant flow in a direction different than the main flow direction of the third channel will occur. Thus, the aerosol will not come into contact with the wall of the third channel immediately which will provide the opportunity for the aerosol to nucleate. In particular, the isokinetic flow of aerosol and dilution gas enables the establishment of a sheath of air formed by the dilution gas in between the aerosol and the wall of the third channel.

[0013] In particular, the speed of the flow of the aerosol in the first channel is not constant, as it follows a specified puff profile, which varies the speed of the flow over time. The speed of the flow of the dilution gas provided by the second channel will be accordingly controlled. In particular, the flow of dilution gas can be controlled according to the predefined profile regarding the flow of the aerosol in the first channel. In other embodiments, the flow of the aerosol in the first channel can be measured, and the flow of the dilution gas in the second channel can be controlled accordingly.

[0014] In one embodiment, an outer wall of the first channel forms the inner wall of the second channel at their respective downstream ends. Thus, by providing the common wall for first and second channels, which can in particular be relatively thin or of gradually reducing thickness in the flow direction, the flows of aerosol and dilution gas can be joined in a gentle manner, to not create any turbulences.

[0015] In particular, the second channel has a ring-like cross-section at its downstream end. Thus, the flow of dilution gas provided by the second channel can fully encompass the aerosol flow provided by the first channel. The first channel would also have in particular a circular cross section. Further, the ring-like cross-section of the second channel enables the lowest possible contact area in between the aerosol flow and the dilution gas flow in the third channel, and thus enables to provide a large space in between the aerosol flow and the wall of the third channel with the lowest possible amount of dilution gas.

[0016] In particular, the first channel could be conically shaped at its downstream end. Additionally or alternatively, the first channel protrudes into the upstream end of the third channel. Thus, the flow of the aerosol provided by the first channel is direct slightly towards the inside of the third channel, and a contact of the aerosol with the wall of the third channel can be reduced or prevented at the upstream part of the third channel due to the construction.

[0017] In particular, the third channel could be cylindrically shaped. Thus, a high volume to cross-section ratio can be attained, with the wall of the third channel having a comparably small surface, such that adsorption and impaction of aerosol particles on the third wall is reduced.

[0018] In one embodiment, a gap is provided in between the wall of the upstream end of the third channel and the wall of the downstream end of the first channel, wherein the gap is forming the downstream end of the second channel. Thus, a smooth transition of the flows from the first and second channels to the third channel can be established, and turbulences or flow perpendicular to the main flow direction in the third channel can be reduced, such that less of the unstabilized aerosol comes in contact with the wall of the third channel.

[0019] Preferably, the aerosol dilution device comprises a chamber, into which the first channel protrudes from one side wherein an upstream portion of the second channel is formed in between the wall of the third channel and the chamber wall. Thus, a compact device can be provided, wherein the first channel can be designed to be relatively short, such that not much loss of particles of the aerosol in the first channel occurs.

[0020] The wall of the first channel and the wall of the third channel may be formed by inserts in the chamber. In particular, the chamber may be formed from one or two joined blocks of material. This allows, that the aerosol dilution device can be easily manufactured, as only the blocks of the chamber, and the inserts have to be assembled. Further, the geometry of the inserts can be adapted to different configurations for the aerosol dilution device, and, therefore, a versatile system is obtained.

[0021] The invention also relates to an automatic smoking machine, comprising an aerosol dilution device as specified above, which is arranged downstream of a receiving means for a smoking article.

[0022] The object of the invention is further attained by a method for diluting a stream of aerosol, in particular provided by a smoking article, with a stream of dilution gas, in particular air, wherein the stream of dilution gas forms a sheath in between a wall of a diluting section and the stream of the aerosol when the streams are joined. Thus, as the aerosol is in an unstabilized state before dilution, the stream of dilution gas prevents contact of the particles of the aerosol with a wall of the diluting section, such that the particles remain in the flow, and are not lost through condensation, diffusion or impaction on the wall of the diluting section. As the particles are not adsorbed by the wall of the diluting section, they remain in the stream of aerosol and dilution gas, and a proper analysis of the diluted aerosol can be carried out. If particles of the aerosol would be lost, the content of the particles in the aerosol originally provided by the smoking articles could not be determined in a reliable manner, and therefore an analysis of the original aerosol would not be possible.

[0023] Preferably, the stream of aerosol and the stream of dilution gas are flowing at substantially the same speed when they are joined. Thus, the streams of the aerosol and the dilution gas are isokinetic. This reduces any turbulences or flow in other directions than the main flow direction, and thus prevents a quick mixing of dilution gas and the aerosol. During the slow mixing process, which is established by the method according to the invention, the aerosol can further stabilize until its particles come into contact with the wall of the diluting section. Thus, a loss of particles of the aerosol can be reduced or prevented.

[0024] Preferably, the stream velocity of the aerosol is variable, and stream velocity of the dilution gas is controlled to correspond to the stream velocity of the aerosol. This is due to the fact that the stream velocity of the aerosol usually follows a puff profile, which simulates the puff of a consumer on a smoking article. Thus, to enable that the dilution gas forms a particularly stable sheath in between the wall of the diluting section and the stream of aerosol, the streams of dilution gas and aerosol are flowing at substantially the same speed when they are joined. The stream velocity of the dilution gas is controlled or adapted to correspond to the stream velocity of the aerosol. This prevents that significant flow in a direction different from the main flow direction in the diluting section is created. Thus, the dilution of the aerosol takes place slowly, and the aerosol can stabilize, before its particles come into first contact with the wall of the diluting section.

[0025] Preferably, the aerosol is provided by a smoking article which heats an evaporable material, and the aerosol comprises components which condense when diluted with air. This particularly applies to the new types of smoking articles as defined in the above prior art discussion, where evaporable material is heated, in particular by other heating means, such as an electrical heating or a gas burner, but not burned as in common cigarettes.

[0026] Preferably, the temperature of the dilution gas is controlled to be different from ambient temperature. Alternatively, the temperature of the dilution gas can be controlled to be of the same temperature as the aerosol. The temperature of the aerosol can be measured, and the temperature of the dilution gas can be accordingly adapted. In other embodiments, the temperature of the aerosol is generally known, and the temperature of the dilution gas is accordingly set.

[0027] The object of the present invention is further attained by an aerosol dilution device for automatic smoking machines, comprising a first channel for an aerosol, in particular provided by a smoking article, and a second channel for a dilution gas, in particular air, wherein the first channel and the second channel terminate at their downstream ends in a third channel, wherein the aerosol dilution device is adapted to establish at the upstream side of the third channel a flow of the dilution gas of the second channel at substantially the same speed as the flow of the aerosol of the first channel.

[0028] All features as defined above with respect to the invention may be combined with this type of aerosol dilution device.

[0029] Furthermore, the object of the invention is attained by a method for diluting a stream of aerosol, in particular provided by a smoking article, with a stream of dilution gas, in particular air, wherein the stream of aerosol and the stream of dilution gas are flowing at substantially the same speed when they are joined.

[0030] All features regarding the method for diluting a stream of aerosol as specified above may be combined with this type of method.

[0031] The invention will now be further explained by means of an exemplary embodiment.

[0032] Figure 1 shows a cross-section of an embodiment of an aerosol dilution device according to the invention.

[0033] According to Figure 1, the aerosol dilution device according to an embodiment of the invention comprises a main block 1 and an upstream block 2, which are fixed to each other. The aerosol dilution device may be part of an automatic smoking machine, or may be connected to an automatic smoking machine. A pump for the aerosol may be arranged upstream of the aerosol dilution device.

[0034] A conical, hollow first insert 3 is arranged in the main block 1, and protrudes into an inner chamber 4 formed in the main block 1. The first insert 3 forms a first channel 5, through which an aerosol 10 is provided. The flow direction of the aerosol 10 is indicated by the corresponding arrow. The first insert 3 reduces its diameter in the flow direction of the aerosol 10. The first channel 5 may further extend through the upstream block 2, wherein the upstream block 2 may be a receiving means for a smoking article. Alternatively, no upstream block 2 may be provided, but the aerosol 10 from a smoking article may be provided in a different manner to the first channel 5.

[0035] As the invention mainly relates to new types of smoking articles, which in contrast to cigarettes do not produce a stabilized aerosol, but rather an aerosol with unstabilized particles, the length of the first channel 5 is preferred to be rather short, such that no or little loss of particles of the aerosol due to depositing on the surfaces of the first channel by condensation, diffusion or impaction occurs. The aerosol is provided with a varying flow velocity according to a predetermined flow velocity. In particular, around 55 milliliters of aerosol are provided as one puff of a puff profile. The flow velocity of each puff quickly increases, then reaches its maximum, and subsequently decreases until the puff is finished. In between the puffs a predetermined pause with no or little aerosol flow is provided.

[0036] From the opposing side as the first insert 3, a second insert 6 protrudes into the chamber 4. The second insert 6 has a generally cylindrical, hollow shape, and forms in its inside a third channel 7. The second insert 6 protrudes further into the chamber 4 than the first insert 3. The second insert 6 has a larger inner diameter than the outer diameter of the downstream end of the first insert 3. The first insert 3 extends with its downstream end into the upstream end of the second insert 6.

[0037] The second insert 6 has a lower diameter, than the diameter of the generally cylindrically formed chamber 4, wherein the orientation of the cylindrical volume forming the chamber 4 and the hollow cylindrical volume of the second insert 6 is in the same direction, namely their longitudinal axes extend substantially along or parallel to each other. Thus, in between the inner wall of the chamber 4 and the outer wall of the protruding part of the second insert 6, a longitudinally extending volume with a substantially ring-like cross-section is provided. This volume forms part of a second channel 8.

[0038] The upstream part of the second channel 8 is formed by a bore 4 or hollow cylindrical insert 9 extending from the outside of the main block 1 into the chamber 4 perpendicular to the flow direction of the aerosol in the first channel 5 or third channel 7. Then, the second channel 8 extends inside the chamber 4 and outside the second insert 6 in a direction opposite to the flow direction of aerosol in the third channel 7. At the side wall of the chamber 4 through which the first insert 3 is provided, the second channel 8 changes its direction to the opposite side. Then, the second channel 8 is generally defined by upstream inside wall of the second insert 6 and the outside of the first insert 3. Thus, at the downstream end of the first channel 5, which is the downstream end of the first insert 3, the second channel 8 has a ring-like cross-section.

[0039] Through the second channel 8, a dilution gas, in particular air, is provided. About 55 milliliters of dilution gas per puff are provided according to a flow velocity profile, which corresponds to the flow velocity profile of aerosol flow. The flow of dilution gas is indicated by the arrow 20. The area of the cross-section of the downstream end of the first channel 5 and of the downstream end of the second channel 8 are substantially the same. Thus, the flow velocity of the dilution gas 20 and the aerosol 10 are substantially the same at the upstream end of the third channel 7. However, the area of the cross-section of the downstream end of the first and second channels 5, 8 may not be the same, and, therefore, the volumes of aerosol 10 and dilution gas 20 per puff may be varied and not be the same. As can be seen in Figure 1, the flow of dilution gas 20 is provided in between the wall of the third channel 7 formed by the second insert 6 and the aerosol flow 10. Thus, during the initial dilution of the unstabilized aerosol, the aerosol 10 does not come into contact with the wall of the third channel 7. During dilution, the aerosol stabilizes, in particular as not yet condensed components of the aerosol have the opportunity to nucleate or contribute to the growing of already formed particles.

[0040] When the diluted aerosol 30 leaves the third channel 7 and is further processed for analysis, it is stabilized. Thus, the aerosol dilution device according to the invention provides a way of processing unstabilized aerosols as provided by some new types of smoking articles.

[0041] According to one embodiment of the method for diluting a stream of aerosol 10 according to the invention, the stream of aerosol 10 is provided through a first channel 5 to a central portion of an upstream end of a third channel 7. At the same time, a stream of dilution gas 20 is provided through a second channel 8, wherein the downstream end of the second channel 8 extends around the downstream end of the first channel 5. Thus, a sheath of dilution gas 20 is provided around the aerosol 10 in the third channel 7. In particular, the stream of aerosol 10 and the stream of dilution gas 20 are flowing at substantially the same speed at the upstream end of third channel 7, such that initial dilution can take place without contact of the particles of the aerosol 10 with the wall of the third channel 7. Thus, while flowing in the third channel 7, the aerosol 10 is diluted by the dilution gas 20, and the diluted aerosol 30 leaves the third channel 7 at the downstream end of the third channel 7 in a stabilized state. In particular, the stream velocity of the aerosol 10 and the dilution gas 20 may be synchronized. The stream velocity of the aerosol and of the dilution gas may be controlled to correspond to a predetermined puff profile, which comprises pauses in between individual puffs.

Claims

1. Aerosol dilution device for automatic smoking machines, comprising a first channel for an aerosol and a second channel for a dilution gas, in particular air, wherein the first channel and the second channel both release their downstream ends in a third channel, with the second channel arranged around the first channel at the upstream side of the third channel.

2. Aerosol dilution device according to claim 1, wherein the aerosol dilution device is adapted to establish at the upstream side of the third channel a flow of the dilution gas of the second channel at substantially the same speed as the flow of the aerosol of the first channel.

3. Aerosol dilution device according to claim 1 or 2, wherein the outer wall of the first channel forms the inner wall of the second channel at their respective downstream ends.

4. Aerosol dilution device according to any one of the previous claims, wherein the second channel has a ring-like cross-section at its downstream end.

5. Aerosol dilution device according to any one of the previous claims, wherein the first channel is conically shaped at its downstream end, and protrudes into the upstream end of the third channel.

6. Aerosol dilution device according to any one of the previous claims, wherein the third channel is cylindrically shaped.

7. Aerosol dilution device according to any one of the previous claims, wherein in between the wall of the upstream end of the third channel and the wall of the downstream end of the first channel, a gap is provided forming the downstream end of the second channel.

8. Aerosol dilution device according to any one of the previous claims, wherein a chamber is formed into which the first channel protrudes from one side, and the third channel protrudes from the other side, wherein an upstream portion of the second channel is formed in between the wall of the third channel and the chamber wall.

9. Aerosol dilution device according to claim 8, wherein the wall of the first channel and the wall of the third channel are formed by inserts in the chamber.

10. Automatic smoking machine, comprising an aerosol dilution device according to any one of the previous claims, which is arranged downstream of a receiving means for a smoking article.

11. Method for diluting a stream of aerosol, in particular provided by a smoking article, with a stream of dilution gas, in particular air, wherein the stream of dilution gas forms a sheath in between a wall of a diluting section and the stream of the aerosol when the streams are joined.

12. Method according to claim 11, wherein the stream of aerosol and the stream of dilution gas are flowing at substantially the same speed when they are joined.

13. Method according to claim 11 or 12, wherein the stream velocity of aerosol is variable, and the stream velocity of the dilution gas is controlled to correspond to the stream velocity of the aerosol.

14. Method according to any one of claims 11 to 13, wherein the aerosol is provided by a smoking article which heats an evaporable material, and the aerosol comprises components which condense when diluted with air.

15. Method according to any one of claims 11 to 14, wherein the temperature of the dilution gas is controlled to be different from ambient temperature.

Drawing