Patent Publication Number: US-2007102013-A1

Title: Electrical smoking system

Description:
FIELD OF THE DISCLOSURE  
      This disclosure relates generally to tobacco smoking systems using electrical energy rather than combustion. More particularly, the smoking system disclosed here generates an aerosol through conductive and/or convective combustionless heating of tobacco by an electrical heating source.  
     SUMMARY  
      A quantity of tobacco is placed in contact with a heating system. Passageways are provided for air to move through the heating system and the tobacco. The heating system raises the temperature of the tobacco to the range of about 150 to about 220° C. by direct contact with the tobacco, by convective heat transfer to the tobacco, and/or by heating the air which in turn heats the tobacco. The heated tobacco releases volatiles which subsequently cool to form an aerosol for delivery from the heating system.  
      The tobacco may have a variety of shapes including without limitation a pillow shape, a generally rotationally symmetric shape, a generally cylindrical plug, a generally cylindrical shell, a generally circular disk, a plug shape, a pellet shape, a cigarette shape, and the like.  
      The heating system may also have a variety of configurations. By way of example, and without limitation, the heating system may include a heating element such as a generally cylindrical heated shell with both ends open, a generally cylindrical heated shell with a closed end, an insertable heating element, a heated disk, a pair of heated disks, or the like. Such heating elements may be fabricated from an electrically resistive material which heats when electrical current passes through it. Such heating elements may also include either internal or external heating devices such as wires. Air may pass axially through the tobacco and the heating system. Alternatively, air may enter the tobacco radially and exit substantially axially. In addition, the heating system may be arranged such that air is preliminarily heated before being directed into the tobacco.  
      If desired, a mouthpiece, with or without a filter, may be used with the heating system both to define a cooling region for the tobacco volatiles, and to direct the resulting aerosol to the consumer. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The accompanying drawings depict several embodiments of the electrically heated tobacco smoking system of this disclosure. In the accompanying drawings, like reference numerals are applied to like elements.  
       FIG. 1  is a cross-sectional view of an electrically heated tobacco smoking system.  
       FIG. 2  is a cross-sectional view of the electrically heated tobacco smoking system taken along the line  2 - 2  of  FIG. 1 .  
       FIG. 3  is a cross-sectional view of another embodiment of the electrically heated tobacco smoking system.  
       FIG. 4  is a cross-sectional view taken along the line  4 - 4  of  FIG. 3 .  
       FIG. 5  is a cross-sectional view of the electrically heated smoking system of  FIG. 1  including a mouthpiece.  
       FIG. 6  is an end view of the electrically heated tobacco smoking system of  FIG. 5 .  
       FIG. 7  is a cross-sectional view of a third embodiment of the electrically heated tobacco smoking system.  
       FIG. 8  is an end view of the electrically heated tobacco smoking system of  FIG. 7 .  
       FIG. 9  is a cross-sectional view of an electrically heated tobacco smoking system using a pillow of tobacco material.  
       FIG. 10  is an end view of the electrically heated tobacco smoking system of  FIG. 9 .  
       FIG. 11  is a cross-sectional view of an electrically heated tobacco smoking system having radial inflow of air.  
       FIG. 12  is an end view of the electrically heated tobacco smoking system of  FIG. 11 .  
       FIG. 13  is a cross-sectional view of an electrically heated tobacco smoking system having counter-current heat exchange.  
       FIG. 14  is an end view of the electrically heated tobacco smoking system of  FIG. 13 .  
       FIG. 15  is a cross-sectional view of an electrically heated tobacco smoking system with a toroidal tobacco mass.  
       FIG. 16  is a cross-sectional view taken along line  16 - 16  of  FIG. 15 . 
    
    
     DETAILED DESCRIPTION  
      Turning to  FIG. 1 , an electrically operated tobacco smoking system  20  according to this disclosure is depicted. The smoking system  20  includes at least a heating system  22  and a tobacco mass that may comprise a plug  24  of cut filler tobacco. The heating system may be an inductively heated arrangement, a resistively heated arrangement, a radiantly heated arrangement, or a convectively heated arrangement. Here, resistively heated arrangements will be described as currently preferred embodiments. The tobacco plug  24  preferably weighs in the range of 5 to 500 mg. For single and multiple puff applications, weights in the range of 5 to 150 mg. are more preferable. Weights in the range of 300 to 500 mg. are more preferable where tobacco is to be used on multiple occasions. The tobacco mass may be made from any type of tobacco, or from any portion of the tobacco plant including, without limitation, sheet products, dust, leaf, stem, and combinations thereof. In the final form, the tobacco mass could involve any type of common tobacco processing steps including, without limitation, blending, flavoring, and the like.  
      If desired, the tobacco plug  24  may include a paper or mesh cover or carrier to facilitate handling. When paper is used around the tobacco plug, the paper substrate may have porosity and weight selected according to the particular shape of the heating chamber and the manner in which the tobacco plug  24  is to be used. For example, where the tobacco plug  24  is replaceable, the paper needs to have sufficient strength to maintain integrity of the tobacco plug during handling, removal, and insertion. Moreover, where the paper covers the principal movement of air through the smoking system, the paper needs to have sufficient porosity to allow air movement therethrough. Where a mesh material is selected, mesh opening should be sized small enough to contain a substantial majority, if not all, of the cut filler tobacco particles.  
      The tobacco mass may also be formed from tobacco particles. Whether particles or other tobacco cuts are used, the tobacco itself may function as a binder to hold tobacco pieces in a preferred shape. If desired, the tobacco used in the system can be pretreated to enhance flavor generation. Similarly, if desired, flavorants can be provided on the tobacco surface.  
      The tobacco mass may be rotationally symmetric in shape or configuration. Moreover, the tobacco mass may be generally cylindrical, disk-like, or generally toroidal. Where a cylindrical configuration is adopted, it may be solid or shell-like with an open center. The particular shape of the tobacco mass is preferably adapted to the shape of the heating apparatus.  
      The heating system  22  substantially encloses or surrounds a substantial portion of the tobacco mass such that at least part of the surface of the tobacco mass conforms to the heating apparatus. An actuation system connected with the heating system  22  is operable to electrically energize the heating system  22 . The actuation system may include a source of electrical energy such as one or more batteries  37 . To preserve battery life and to control activation of the heating system  22 , a suitable switch  38  may be connected in series with the batteries  37 . Depending on the application, the switch  38  may be a push-button switch, a flow sensing device, or a puff sensing device. A suitable conductor  36  connects the batteries  37 , the switch  38 , and the heating system  22  in series.  
      The heating system  22  is operable to heat the tobacco mass to a temperature in the range of about 150° to about 220° C. to release flavorful volatiles without reaching the tobacco kindling temperature and without generating smoke and/or ash. Further, the heating system defines a heat transfer channel or pathway through which air is directed.  
      As shown, the heating system  22  may comprise a generally cylindrical shell having both ends open. As best seen in  FIG. 2 , the generally cylindrical shell surrounds the sides of the tobacco plug  24 . The heating system  22  is electrically energized to generate heat. To that end, the heating system  22  may be connected to a suitable source of electrical energy, such as, for example, domestic power grid, portable power generating devices like an automobile cigarette lighter, batteries, and any other suitable conventional source. The source of energy must be capable of delivering heat from the heating system  22  to the tobacco plug  24  so that the tobacco in the plug is raised to a temperature in the range of about 150° C. to about 220° C. Within this temperature range, the tobacco releases flavorful volatiles that produce a satisfying experience while generating little to no visible smoke.  
      The heating system  22  may operate continuously for a period of time corresponding to the length of time normally used to smoke a cigarette. Conventionally, that length of time is typically taken as about 5 to 10 minutes. Alternatively, the heating system  22  may operate intermittently, on demand, for example in response to puffs by the system user.  
      In use, the heating system  22  is activated, for example, by a puff sensor or a suitable “on-off” device. Ambient air  26  is drawn through the open end  28  of the heating system  20  and into the tobacco plug  24 . The heating system  22  closely conforms to the periphery of the tobacco plug  24  and heats the tobacco plug  24  to the desired temperature range (about 150° C. to about 220° C.) by conductive and/or convective heat transfer to release flavorful volatiles from the tobacco. As the ambient air  26  moves through the tobacco plug  24 , the air  26  entrains the released tobacco volatiles and distills those volatiles by cooling them. As the air with entrained volatiles leaves the second end of the heating system  22 , see arrow  30 , exposure to ambient air further cools the entrained volatiles to form an aerosol  32  which is delivered from the heating system  22 .  
      If desired, an aerosol former may be added to the tobacco plug  24 . Suitable aerosol formers include, for example, glycerol, propylene glycol, triacetin, and the like, as well as mixtures thereof. Concentrations of aerosol former in the range of about 0 to about 25% by weight can be used. The aerosol formers also enhance tobacco involvement in the aerosol formation.  
      After the tobacco plug  24  has been used, it may be removed from the heating system  22  and replaced with a fresh plug or cartridge. The spent tobacco plug  24  may be discarded.  
      It will be appreciated by those skilled in the art that the electric tobacco smoking system described herein provides numerous advantages. For example, a smaller amount of tobacco is used so tobacco supplies can be extended. By using less tobacco, the disposable waste from the smoking experience is also reduced. In addition, since the heating system releases principally the flavorful volatiles from the tobacco which may be perceived as more pleasing than the sidestream aroma resulting from cigarette combustion.  
      The tobacco plug  24  is not subject to actual combustion as occurs with lit-end smoking articles. Because the electric tobacco smoking system described here does not have a smoldering coal, it presents less risk of starting a fire when carelessly handled than a conventional lit-end cigarette. For the same reason, the smoking system herein described requires less cleaning as there is essentially no ash with which to contend. Furthermore, the disposable waste which does exist has less residual aroma due to the lack of combustion. Moreover, absence of smoke should obviate non-smoker objections to second-hand smoke.  
      Of course, various other embodiments of the electric tobacco smoking system are not only possible but also are within the scope of this disclosure. For example (see  FIG. 3 ), the tobacco plug  24  may be substantially enclosed by the heating system  22 . In this embodiment, the heating system may include a heater  40  that is received within a generally cylindrical shroud  42 . The actuation system of  FIG. 3  is like that of  FIG. 1  and includes conductors  36 , batteries  37 , and a switch  38 .  
      To provide one or more channels for air flow around the heater  40 , the heater  40  and/or the shroud  42  may include two or more radially outwardly extending ribs  44 ,  46  (see  FIG. 4 ) which are operable to space the heater  40  from the shroud  42 . The ribs  44 ,  46  may extend longitudinally along the outer surface of the heater  40 . The ribs  44 ,  46 , cooperate with the shroud  42  and the heater  40  to define a pair of preheating chambers or channels  48 ,  50  through which air can enter the smoking system as indicated by the arrows in  FIG. 3 . At least one of the ribs  44 ,  46  also extends axially beyond the heater  40  and functions as a spacer to hold the heater  40  away from the end wall  52  of the shroud  42 .  
      The cross-sectional area of the channels  48 ,  50  may be selected as desired. For example, it may be desired to provide a flow area around the heater  40  which is equivalent to the flow area through the inside of the heater  40 . Or, it may be desired to provide a flow area equivalent to the flow area through the tobacco plug  24 . Regardless of the flow area selected, the heater  40  is preferably spaced from the end wall  52  by a sufficient distance that the flow area at the inner end of the heater  40  is at least as large as the flow area through the channels  48 ,  50 . In this manner, the puff resistance (resistance-to-draw) is defined by the tobacco plug rather than by the assembly of the heater  40  and the shroud  42 .  
      With the arrangement of  FIGS. 3 and 4 , air entering the electric tobacco smoking system, see arrows  54 , flows axially through the preheating chambers or channels  48 ,  50  between the heater  40  and the shroud  42 . During that time, the air is heated by thermal energy that might otherwise escape from the outer surface of the heater  40 . That air then passes around the end of the heater, and flows through the tobacco plug  24  where it picks up flavorful volatiles from the tobacco heated by the heater  40 . As the air  54  leaves the heater  40 , it cools so that the volatiles condense and form the aerosol  56  for delivery from the heating system  22 .  
      If desired, the spacing between the heater  40  and the shroud  42  may be accomplished with structures other than the longitudinal ribs described above. For example, discontinuous ribs, radially extending pins, and baffles may be used as desired. Baffles might be used to improve heat transfer to air under some circumstances.  
      Thus, the embodiment of  FIGS. 3 and 4  improves the heat transfer to air and is more efficient than embodiments without the shroud  42 .  
      The electric tobacco smoking system of this disclosure may also include a mouthpiece  60  (see  FIGS. 5 and 6 ) having an end in fluid communication with the tobacco mass. The mouthpiece  60  may be constructed and arranged such that it has a cross-sectional configuration corresponding to the cross section of the heater assembly  22 . In addition, the mouthpiece  60  may include a generally cylindrical shell  62  and an attachment sheath  64 . The shell  62  preferably extends outwardly from the tobacco plug  24 , has an open interior, and provides a channel or passage to deliver the aerosol  32 . The shell  62  also functions to provide structural support for the heater  22  and tobacco plug  24 . The sheath  64  preferably surrounds the shell  62  and may be constructed from paper or any other suitable conventional material.  
      The sheath  64  extends beyond the end of the shell  62  and into an opening within the heating assembly  22 , which opening may be between the heating assembly  22  and the tobacco mass. By attaching the sheath  64  to the electric tobacco smoking system  20 , the combination of the smoking system  20  and the mouthpiece  60  cosmetically resembles a conventional cigarette.  
      When more than one mouthpiece  60  will be used with the smoking system  20 , or when one mouthpiece  60  will be used with more than one smoking system  20 , the sheath may be fabricated from a sufficiently rigid material that the mouthpiece can be removably attached to the smoking system  20  by inserting the extending portion of the sheath  64  between the heating assembly  22  and the tobacco plug  24 . For some applications, it may also be desirable to provide a suitable filter (not shown) such as a plug of cellulose acetate in the discharge end of the mouthpiece  60 . Typically, such a filter would be located at an end of the mouthpiece. The actuation system of  FIG. 5  is like that of  FIG. 1  and includes conductors  36 , batteries  37 , and a switch  38 ; however, in  FIG. 5 , the switch  38  may be a puff sensing device or an air flow sensing device.  
      Another arrangement for the heating assembly is shown in  FIGS. 7 and 8 . In this embodiment, the heating assembly includes an end piece  70  and a projection  72 . The projection  72  may, for example, be a rod constructed and arranged so that it can be inserted into and received by the tobacco plug  24 . The axial length of the projection  72  is selected so that it does not extend all the way through the tobacco plug. The end piece or heater disk  70  includes air passages or openings  74 ,  76  through which air can be introduced into the tobacco plug  24 . At least one of the end piece  70  and the projection  72  may be energized to generate heat, e.g., by resistance heating or induction heating. Presently it is contemplated that both the end piece  70  and the projection  72  are capable of generating heat. However, if the tobacco plug  24  has a small diameter compared to the transverse dimensions of the projection  72 , sufficient heat may be generated by the projection  72  that additional heat from the end piece  70  is not needed. The actuation system of  FIG. 7  is like that of  FIG. 1  and includes conductors  36 , batteries  37 , and a switch  38 .  
      While the end piece  70  is depicted with two openings, the number, arrangement, and shape of the openings can vary. For example, a pattern of circular holes could be used if desired. Where the end piece  70  is heated, heat transfer to the air passing through the openings can be increased by using smaller openings.  
      If desired, the heating assembly  70 ,  72  and the associated tobacco plug  24  may be enclosed in other structures. For example, a cylindrical shell may surround the tobacco plug, or the tobacco plug along with the end piece  70 . Such a cylindrical shell could also include a mouthpiece portion.  
      The embodiments discussed above include a generally cylindrical plug of tobacco; however, that shape for the tobacco is not critical. The cross section may be circular, as shown. Alternatively, the cross section can be uniform or non-uniform and can have any desired shape such a polygonal, elliptical, oval, toroidal, and the like. Moreover, the tobacco can have other suitable shapes as will be apparent to those skilled in the art. For example, the tobacco can be shaped as a pillow, i.e., a unit having a depth which is small compared with the transverse dimension. The pillow may be circular, rectangular, polygonal, polygonal with rounded corners, toroidal, or the like.  
      A generally circular embodiment of the pillow arrangement is depicted in  FIGS. 9 and 10 . Here, the pillow  80  is fashioned from cut filler tobacco. As desired, the pillow  80  may include a permeable membrane surrounding it to hold its shape and facilitate handling. The thickness of the pillow  80  may be in the range of 10-80% of a nominal transverse dimension of the pillow  80 . In the context of  FIG. 9 , the nominal transverse dimension would be measured in the vertical direction and would correspond to the diameter of the pillow  80 . The pillow thickness would be measured in the horizontal direction, axially in the direction of airflow.  
      The heating system  82  for this embodiment comprises a heating plate in heat transfer relationship with the tobacco pillow  80 . The actuation system of  FIG. 9  is like that of  FIG. 1  and includes conductors  36 , batteries  37 , and a switch  38 . The plate  82  may be a generally circular disk and may include a plurality of openings  84  to permit air to flow into the pillow  80 . Those openings  84  may have any desired shape. In some applications, the openings  84  will be sized to provide heat transfer from the heating plate  82  to air (see arrows  86 ) before the air enters the tobacco pillow  80 .  
      Thermal energy from the plate  82  is applied to the tobacco pillow  80  by conduction and convection so that the temperature of the pillow is raised to release the flavorful volatiles. As with other embodiments, that temperature lies in the range of about 150° to about 220° C. As air leaves the tobacco pillow with the entrained flavorful volatiles (see arrows  88 ), the flavorful volatiles cool to form an aerosol (see arrow  90 ).  
      A pillow  80  having radial air inflow and axial outflow is shown in  FIGS. 11 and 12 . In this embodiment, the heating arrangement may include a disk-shaped heater  92  and an annular heater  94 . The disk heater  92  and the annular heater  94  are spaced from one another by a distance corresponding to the thickness of the pillow  80  and sandwich the pillow therebetween. Both the disk heater  92  and the annular heater  94  have heat transfer relationship with the pillow  80  so that the heaters  92 ,  94  can raise the temperature of tobacco in the pillow  80  to a temperature sufficient to release the flavorful volatiles (i.e., about 150° to about 220° C.). The actuation system of  FIG. 11  is like that of  FIG. 1  and includes conductors  36 , batteries  37 , and a switch  38 .  
      In this arrangement, ambient air enters the pillow  90  in a generally radial direction, for example, in response to inhalation. As the ambient air passes through the pillow  80 , its temperature rises by heat transfer from one or both of the heaters  92 ,  94  and it entrains volatiles released from the tobacco. Air with the flavorful tobacco volatiles, turns axially and leaves the assembly through a generally circular orifice or opening  96  in the center of the annular heater  94 . The air with entrained tobacco volatiles cools as it leaves the heater and condenses to form an aerosol (arrow  98 ).  
      To enhance the heating efficiency of the embodiment of  FIGS. 11 and 12 , the assembly of a tobacco pillow  80 , the disk heater  92 , and the annular heater  94  may be enclosed in a housing  100  (see  FIGS. 13 and 14 ). The housing  100  may include a wall  102  fabricated from an insulating material to reduce heat loss from the disk heater  92 . Preferably the insulating wall  102  is substantially coextensive with the disk heater  92 . The housing  100  also includes a baffle portion  103  attached to the insulating wall  102  and operable to direct airflow into the tobacco mass. The baffle  103  is spaced radially from both the disk heater  92  and the annular heater  94 . Moreover, the baffle  103  is spaced axially in front of the annular heater  94 . Although the actuation system is not schematically shown in  FIG. 13 , the actuation system for  FIG. 13  is like that of  FIG. 1  and includes conductors, batteries, and a switch.  
      With that arrangement, the baffle  103  forms an internal channel  104 , which receives ambient air through an annular opening  106  and directs that ambient air radially outwardly through a preheating passage, defined between the annular heater  94  and the baffle, to a collector substantially surrounding the peripheral edge of the pillow  80 . As the air passes the annular heater  94  in the channel  104 , the air is heated thereby reducing energy loss or waste from the annular heater  94 . The heated air then passes radially inwardly through the pillow  80  between the disk heater  92  and the annular heater  94  and leaves through the generally circular opening  96 .  
      A generally cylindrical connector tube  108  with a generally circular cross section is fitted into the opening  96  and provides a passageway for heated air with entrained tobacco volatiles leaving the pillow  80  through the opening  96 . In addition, the tube  108  cooperates with the central opening  110  of the baffle  103  to define an annular inlet opening  106 . As air leaves the tube  108 , it cools and the entrained tobacco volatiles form an aerosol.  
      Use of a generally toriodal tobacco mass is depicted in  FIGS. 15 and 16 . Here, the structural characteristics of the electric tobacco heater are essentially the same as those of the heater described above in connection with  FIGS. 13 and 14 . Although the actuation system is not schematically shown in  FIG. 15 , the actuation system for  FIG. 15  is like that of  FIG. 1  and includes conductors, batteries, and a switch. The principal difference being the tobacco mass, which is used. Here the tobacco mass  120  is generally toroidally shaped, i.e., shaped like a donut. The tobacco donut  120  is sandwiched between the disk heater  92  and the annular heater  94  so that the tobacco donut contacts both heaters. In this way, air is forced to travel through the tobacco donut  120 . Preferably, the tobacco donut does not extend outwardly to touch the shell  103  so that the passageway for air is not obstructed.  
      The electric tobacco heater ( FIG. 15 ) is shown with a mouthpiece  122  attached at one end to the tube  108 . At the other end, the mouthpiece  122  may include a suitable filter  124 .  
      It is also contemplated that the tobacco mass may be arranged so that successive portions of the tobacco mass can be advanced to the heating system. Individual tobacco mass portions may be used for a time corresponding generally to one puff, to multiple puffs, or to correspond to a time comparable to the smoking of a conventional cigarette. The embodiments of  FIGS. 9-12  are particularly well suited for such applications. For example, successive tobacco mass portions may be carried on a tape and advanced into position relative to the heating system by a suitable indexing arrangement. Alternatively, the tobacco mass portions may be carried by a cassette, or may comprise discrete packages.  
      The terms and phases used herein are not to be interpreted with mathematical or geometric precision, rather geometric terminology is to be interpreted as meaning approximating or similar to the geometric terms and concepts. Where the term “about” is used in relation to a number, it is intended that such number has a tolerance of plus or minus 5%. Similarly, such terms as “generally” and “substantially” are intended to encompass both precise meanings of the associated terms and concepts as well as to provide reasonable latitude which is consistent with form, function, and/or meaning.  
      It will now be apparent to those skilled in the art that this specification describes a new, useful, and nonobvious smokeless electric tobacco smoking system. It will also be apparent to those skilled in the art that numerous modifications, variations, substitutes, and equivalents exist for various aspects of the invention that have been described in the detailed description above. Accordingly, it is expressly intended that all such modifications, variations, substitutions, and equivalents that fall within the spirit and scope of the invention, as defined by the appended claims, be embraced thereby.