Abstract:
The present invention relate to a smoking device where heated air forms an aerosol which is conveyed to a user without significant burning or combustion of the aerosol supported substrate.

Description:
This application is a Continuation of Ser. No. 09/033,587 filed Mar. 3, 1998, now U.S. Pat. No. 5,996,589. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a smoking device. In particular, the invention relates to a smoking device that generates an aerosol in response to heated air. 
     BACKGROUND OF THE INVENTION 
     Smoking has been a common pastime in many cultures for probably hundreds of years. Conventionally, smoking has been performed using various devices that involve the combustion of tobacco, such as cigarettes, cigars and pipes. The combustion of tobacco produces smoke which is transmitted to a user. In the case of pipes and cigars, the smoke is typically not inhaled by the user, but in the case of cigarettes, the smoke is inhaled. The flavors included within the smoke caused by combusting tobacco produce a pleasurable effect in the user. Various attempts have been made to produce a smoking device that does not rely on tobacco. Many of these devices are adapted to look like conventional smoking articles such as cigarettes. One such example is the simulated smoking device taught in U.S. Pat. No. 4,284,089 to Ray. The simulated smoking device includes a container having an internal source of nicotine. The source of nicotine does not completely fill the air passageway of the container. Thus, a constricted region of the air passageway is created within the source of nicotine. Upon the application of suction by a user at one end of the container, pressure is reduced in the constricted portion of the passageway which causes nicotine to be released from the source of nicotine and enter the passing air. 
     In another device, shown in European Patent No. 0 198 268 to Ellis et al., a smoking device is disclosed which includes a housing for receiving a conventional cigarette at one end and a mouthpiece at the other end for delivering cigarette smoke to a user. Located between the mouthpiece and the conventional cigarette is a nicotine dispensing unit. 
     Still other devices have been developed as an alternative to conventional smoking articles. These articles generally attempt to simulate conventional cigarettes without the combustion of tobacco products. For example, many devices include an internal aerosol forming material that is heated by an internal heating element. The heating stimulates the production of a flavorful aerosol for delivery to a user of the device. The internal heating element has conventionally been either a carbonaceous fuel element, or an electrochemical heat source such as combinations of metal oxide, anhydrous metal sulfide, metal sulfate, inorganic salt and a sugar which generate heat on contact with water. In these devices, the cigarette is not capable of being reused. Once the carbonaceous fuel element is lit it continues to burn unattended until all the fuel in the element is consumed. The lit fuel element is very difficult to extinguish, either with water or other means for extinguishment. If based on an electrochemical reaction, difficulty is also encountered in stopping the reaction which only terminates when all the reactants are consumed. Other devices include an electrical heating element for stimulating an aerosol forming substance. Although these are capable of being turned off between puffs, the electrical heating element requires a battery which is clumsy. 
     It would be desirable to provide an article that closely simulates a conventional cigarette but does not require the combustion of tobacco and can be reused as well. A need also exists for an article where the timing for individual puffs is determined by the user, and not controlled by the time or type of reaction. It would further be desirable to minimize, if not eliminate, combustion by-products of the substrate while heating air is drawn through the device. 
     SUMMARY OF THE INVENTION 
     According to the present invention, a smoking device (article) delivers an aerosol to a user by air at an elevated temperature that passes through the article to contact an aerosol forming component, without significant burning or combustion of the substrate. The article includes a hollow tube defining an air passageway extending between a heating end and a user (mouth) end of the tube. The tube is resistant to burning upon application of a flame or any suitable heating element. An aerosol forming substrate fills and is positioned within the passageway so that the substrate is recessed from the heating end of the tube. As a result, an air gap of a predetermined length is defined between the distal end of the substrate and the heating end of the tube for delivering hot gases from the heat source, e.g. flame, to the substrate without igniting the substrate. The hot gases form and convey the aerosol, which is typically flavored, to the mouth end of the tube upon application of suction. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above-described advantages and salient features of the present invention will be more fully appreciated with reference to the following specification and appended figures. 
     FIG. 1 depicts an article in accordance with the present invention. 
     FIG. 2 depicts an article having both an internal filter and an aerosol forming substrate. 
     FIG. 3 depicts an article according to the present invention having an aerosol forming substrate and a partially positioned internal filter. 
     FIG. 4 depicts an article according to the present invention including a heat diffuser. 
     FIG. 5A depicts an article according to the present invention including a heat diffuser in the form of a perforated diffuser tube. 
     FIG. 5B is an enlarged view of the perforated tube depicted in FIG.  5 A. 
     FIGS. 6A and 6B depict an alternative housing for the article of the present invention. 
     FIG. 7 depicts the operation of the present invention by a user. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 depicts article  10  that includes a tube  12  surrounding an aerosol forming substrate  14 . As used herein, the aerosol forming substrate  14  is a substrate containing an aerosol forming component. The tube  12  is hollow and defines an air passageway between a heating end  18  and a user/mouth end  20 . The tube  12  is heat resistant and will not burn upon application of a flame  21  to the heating end  18 . Suitable materials for use as the tube  12  will be set forth below in greater detail. 
     The aerosol forming substrate  14  is positioned within the tube to fill the inner diameter of the tube. In addition, the aerosol forming substrate  14  is positioned within the tube so that its distal end  15  is recessed from the heating end  18  of the tube  12 . The tube has an internal diameter “d” of between 3 and 16 mm. The gap  16  is of sufficient length to prevent direct contact of a flame with the distal end of the aerosol supported substrate. The distal end of the substrate  14  is preferably recessed from the heating end of the tube a distance of between 2 and 10 times the gap diameter “d”. Therefore, the gap is at least 6 mm. This forms an air gap or conduit  16  between the heating end  18  and the distal end of the substrate  14 . The air conduit  16  provides a path for hot gases to enter the article  10  from the flame  21  to heat the substrate  14  without igniting or substantially burning the substrate  14 . The aerosol forming substrate is air transmissive, thus creating an air transmissive path from the mouth end  20  of the tube  12  to the heating end  18 . The aerosol forming substrate  14  also contributes an aerosol to heated air that passes through it. 
     During use of the article  10 , as seen in FIG. 7, a user applies a flame  21  to the heating end  18  of the tube  12 . This causes hot air and hot gases from the flame  21  to enter the air conduit  16  within the tube  12  when the user applies suction with his/her mouth to the mouth end  20  of the tube  12 . This causes the hot gases produced by the flame  21  to enter the air passageway within the tube  12 . As the user applies suction, the hot gases travel through the aerosol forming substrate  14 , which dispenses an aerosol to the hot gases. Then, the hot air with the aerosol pass into the mouth of the user producing a pleasurable effect. 
     The air conduit or gap  16  is typically at least two centimeters in length and preferably between two and six centimeters in length. The length of the gap is chosen in order to convey hot gases from the flame  21  to the substrate  14  without substantially burning or igniting the substrate  14 . The length of the air conduit  16 , in order to accomplish this goal, depends upon the diameter of the tube  12 . Two to six centimeters is preferred for a tube of conventional cigarette dimensions. If the diameter of the tube  12  is different, the distal end  15  may be recessed more or less than the above range in order to preserve an aspect ratio between the length of recess and the diameter of the tube  12 . 
     The aerosol forming substrate  14  is comprised of a support material having one or more distillable substances imbued therein. Suitable support materials include virtually anything that is porous enough to transmit air and absorbent enough to retain distillable substances. Preferred support materials include fibrous cellulosic material such as paper, cotton, wood pulp, and combinations thereof. In addition, the support material may be tobacco or reconstituted tobacco, carbonized cellulosic material, metal wool, ceramic wool, and porous ceramic. In addition, polymeric materials having sufficient porosity and absorbency may be used. 
     Distillable substances for imbibing into the support material are selected to provide a pleasurable sensation to the user. The distillable substances should volatilize in response to heating by the hot gases from the flame  21 . Suitable distillable substances include water, polyhydric alcohols such as glycerin, propylene glycol, triethylene glycol, glycerol triacetate, triethylene glycol diacetate and combinations thereof. Other examples are tobacco extract, tobacco pyrolysates, aliphatic esters of mono-di-or poly-carboxylic acids, such as methyl stearate, dimethyl dodecandioate, dimethyl tetradecandioate, and mixtures thereof. In addition, flavors may be added to the distillable substances to produce a desired taste effect. Examples of flavorings include cocoa butter, chocolate liquor, waxes, oils, and combinations thereof. In addition, menthol flavor may be added to simulate sensations produced by conventional menthol cigarettes. 
     The distillable substances may be imbued into the support material by dipping the support material into a mixture of distillable substances or by spraying the distillable substances onto the support material. Alternatively, the distillable substance mixture may be forced into the support material under pressure. The aerosol forming substrate  14  may be inserted into a preformed tube  12 , or the tube  12  may be wrapped around the aerosol forming substrate  14 , or the substrate  14  may be wrapped in a combustion resistant wrapper and the resulting article inserted into the tube  12 . 
     The tube  12  is non-combustible upon application of a flame or at least not easily ignited. Suitable materials for the tube  12  are ceramic, meerschaum, metal, paper, paper board, reconstituted tobacco, wood, bamboo, glass, metal foil, and combinations thereof. Any of the foregoing materials may be treated to prevent combustion. Chemical treatments for reducing a propensity for combustion are well known in the art. 
     In addition, suitable plastics such as Bakelite may be used for the tube  12 . The tube  12  may be formed in any convenient manner such as for example, injection blow molding, extrusion and conventional molding. When the tube is preformed, the aerosol forming substrate  14  is typically inserted into the formed tube  12 . Alternatively, the tube  12  may be formed from a planar member or sheet, for example, a chemically treated piece of paper. When the article  10  is made using a sheet for the material of the tube  12 , the sheet is typically rolled around the aerosol forming substrate  14  during manufacture. While particular examples of forming the article  10  have been set forth, it will be understood that any convenient method of manufacturing the article  10  may be used. For example, the tube  12  may be made of a composite of materials. In addition, the tube  12  may be integral or monolithic, or may include a plurality of sections or may be layered. 
     FIG. 2 depicts an alternate embodiment of the invention, in which the article  10  further comprises a filter  22 . The filter  22  is disposed between the aerosol forming substrate  14  and the mouth end  20  of the tube  12 . The filter  22  may simply give the article  10  a more similar appearance to a conventional cigarette. Alternatively, the filter  22  may perform a useful function of filtering the gas delivered to the user. 
     FIG. 3 depicts yet another embodiment of the article  10  in which the filter  22  is partially within the mouth end  20  of the tube  12  and partially outside. In this configuration, a user may grip the filter for ease of removal. This design also limits insertion depth of the article and better control of the gap. 
     In yet another embodiment shown in FIG. 4, a heat diffuser  24  is inserted into the air conduit between the distal end of the aerosol forming substrate  14  and the heating end  18 . The heat diffuser serves to deliver the hot gases from the flame  21  to the aerosol forming substrate  14  through holes contained within the diffuser  24 . In addition, the heat diffuser  24  blocks the flame from contact with the aerosol forming substrate  14  upon the application of suction at the mouth end  20  by the user. This facilitates preventing ignition and substantial burning of the aerosol forming substrate  14 . The heat diffuser  24  may also be treated with a catalyst for converting carbon monoxide into carbon dioxide. The heat diffuser  24  may also be treated with other catalysts for eliminating certain hydrocarbons produced by various types of flames and heating elements. The flame  21  may be produced for example by a match, a butane lighter, or a gaseous lighter incorporating any other type of gas for controlled combustion. It is also within the scope of the invention to fixedly or removably attach the lighter to the end of tube  10 . Conversely, a heating element that does not flame may be used to introduce the hot gases into the tube  12 . In a preferred embodiment of the invention, the heat diffuser  24  is a wire mesh. 
     FIGS. 5A and 5B show yet another alternate embodiment of the invention wherein the heat diffuser is in the form of a hollow perforated diffuser tube  26 . The hollow perforated diffuser tube  26  is inserted within the aerosol forming substrate  14 . Such a diffuser tube facilitates the transmission of the hot gases from the flame  21  to a larger surface area of the aerosol forming substrate  14 . In addition, the diffuser tube may lower the pressure drop across the aerosol forming substrate  14 , thus rendering it more easy for a user to suck gases from the heating end  18  to the mouth end  20 . In this configuration, the proximal end of the diffuser tube  26  which is adjacent to the mouth end  20  of the tube  12  does not completely extend beyond the aerosol forming substrate  14 . Therefore, there is no direct path for air at the heating end  18  to reach the mouth end  20  without going through the aerosol generating substrate  14 . 
     As was indicated above, the filter  22  may or may not be used. When the filter  22  is used, it typically abuts the proximal end of the aerosol forming substrate  14  at one end. When it is not used, the proximal end of the aerosol forming substrate  14  is nearly coincident with the mouth end of the tube  12 . 
     In FIGS. 6A and 6B, the Article  10  includes a tube  100  having a thickness  102 , an inner diameter  104  also includes openings  106  and cutout  108 . The use of openings  106  ensures the proper use of the article. If the user does not place the charge in tube  100  to form the distal gap (gap  16  in FIG.  1 ), air will be drawn into the holder through holes  106  instead of the end  112  of holder  100 . Tube  100  is also provided with cut-out  104 , which permits easy removal of a filter bearing substrate. 
     Although specific embodiments of the invention have been disclosed, it will be understood by those of ordinary skill in the art that changes may be made to those embodiments without departing from the spirit and scope of the invention. For example, in the preferred embodiment of the present invention, the article has the dimensions of a conventional cigarette. However, the dimensions including the diameter, length, and shape of the tube may be changed without departing from the scope of the invention.