United States Patent (19)
`Sensabaugh, Jr. et al.
`
`11
`45
`
`Patent Number:
`Date of Patent:
`
`4,793,365
`Dec. 27, 1988
`
`54 SMOKING ARTICLE
`75 Inventors: Andrew J. Sensabaugh, Jr.,
`Winston-Salem; Henry T. Ridings,
`Lewisville; John H. Reynolds, IV,
`Winston-Salem, all of N.C.
`Assignee: R. J. Reynolds Tobacco Company,
`Winston-Salem, N.C.
`Appl. No.: 650,604
`Filed:
`Sep. 14, 1984
`Int. Cl." ............
`A24D 1/00; A24D 1/02;
`A24D 1/18; A24F 1/00
`U.S. Cl. ............
`131/360; 131/361; 131/364; 128/202.21
`Field of Search -
`131/194, 335, 195, 196, 197
`References Cited
`U.S. PATENT DOCUMENTS
`0,117,355 9/1984
`Hearn .
`1,529, 181 3/1925
`Holines .
`1,770,616 7/1926
`Kean .
`Bromberg .
`3,713,451 1/1973
`3,886,954 6/1975
`Hannema et al. .
`4,027,679 7/1977
`Kaswan .
`4,407,308 10/1983
`Baker .
`4,474,191 10/1984
`Steiner .
`4,481,958 11/1956
`Rainer et al. .
`4,570,650 2/1986
`Sirota .
`FOREIGN PATENT DOCUMENTS
`687136 5/1964 Canada .
`
`8 & 8 w to w
`
`we w w 48 88 4 0. 131/194; 131/335;
`
`-
`
`-
`
`-
`
`-
`
`-
`
`- - 131/360, 361, 364, 359,
`
`(73)
`
`(21)
`22
`(51)
`(52)
`(58)
`
`56)
`
`
`
`2057421 4/1971 France.
`2057422 4/1971 France .
`35-9894 5/1960 Japan.
`956544 4/1964 United Kingdom .
`Primary Examiner-V. Millin
`Attorney, Agent, or Firm-Grover M. Myers; David G.
`Conlin
`ABSTRACT
`57
`The present invention relates to a smoking article which
`produces an aerosol that resembles tobacco smoke, but
`contains no more than a minimal amount of incomplete
`combustion or pyrolysis products.
`The smoking article of the present invention provides
`an aerosol "smoke' which is chemically simple, consist
`ing essentially of oxides of carbon, air, water, and the
`aerosol which carries any desired flavorants or other
`desired volatile materials, and trace amounts of other
`materials. The aerosol "smoke' has no significant muta
`genic activity as measured by the Ames Test. In addi
`tion, the article may be made virtually ashless so that
`the user does not have to remove any ash during use.
`One embodiment of the present smoking article com
`prises a short combustible carbonaceous fuel element; a
`short heat stable, preferably carbonaceous substrate
`bearing an aerosol forming substance, and a relatively
`long mouthend piece. The fuel element and the sub
`strate are arranged in a heat exchange relationship,
`thereby causing aerosol formation without significant
`degradation of the aerosol former.
`
`50 Claims, 3 Drawing Sheets
`
`Philip Morris Products, S.A.
`Exhibit 1011
`Page 001
`
`

`

`U.S. Patent Dec. 27, 1988
`
`Sheet 1 of 3
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`4,793,365
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`Philip Morris Products, S.A.
`Exhibit 1011
`Page 002
`
`

`

`U.S. Patent Dec. 27, 1988
`
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`4,793,365
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`Philip Morris Products, S.A.
`Exhibit 1011
`Page 003
`
`

`

`U.S. Patent Dec. 27, 1988
`
`Sheet 3 of 3
`
`4,793,365
`
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`Philip Morris Products, S.A.
`Exhibit 1011
`Page 004
`
`

`

`5
`
`15
`
`SMOKING ARTICLE
`
`BACKGROUND OF THE INVENTION
`The present invention relates to a smoking article
`which produces an aerosol that resembles tobacco
`Smoke which contains no more than a minimal amount
`of incomplete combustion or pyrolysis products.
`Many smoking articles have been proposed through
`10
`the years, especially over the last 20 to 30 years. But
`none of these products has ever realized any commer
`cial success.
`Tobacco substitutes have been made from a wide
`variety of treated and untreated plant material, such as
`cornstalks, eucalyptus leaves, lettuce leaves, corn
`leaves, cornsilk, alfalfa, and the like. Numerous patents
`teach proposed tobacco substitutes made by modifying
`cellulosic materials, such as by oxidation, by heat treat
`ment, or by the addition of materials to modify the
`properties of cellulose. One of the most complete lists of
`20
`these substitutes is found in U.S. Pat. No. 4,079,742 to
`Rainer et al. Despite these extensive efforts, it is be
`lieved that none of these products has been found to be
`completely satisfactory as a tobacco substitute.
`Many proposed smoking articles have been based on
`25
`the generation of an aerosol or a vapor. Some of these
`products produce an aerosol or a vapor without heat.
`See, e.g., U.S. Pat. No. 4,284,089 to Ray. However, the
`aerosols or vapors from these articles fail to adequately
`simulate tobacco smoke.
`30
`Some proposed aerosol generating smoking articles
`have used a heat or fuel source in order to produce an
`aerosol. However, none of these articles has ever
`achieved any commercial success, and it is believed that
`none has ever been widely marketed. The absence of
`35
`such smoking articles from the marketplace is believed
`to be due to a variety of reasons, including insufficient
`aerosol generation, both initially and over the life of the
`product, poor taste, off-taste due to the thermal degra
`dation of the smoke former and/or flavor agents, the
`presence of substantial pyrolysis products and side
`stream Smoke, and unsightly appearance.
`One of the earliest of these proposed articles was
`described by Siegel in U.S. Pat. No. 2,907,686. Siegel
`proposed a cigarette substitute which included an ab
`45
`sorbent carbon fuel, preferably a 2 inch stick of char
`coal, which was burnable to produce hot gases, and a
`flavoring agent carried by the fuel, which was adapted
`to be distilled off incident to the production of the hot
`gases. Siegel also proposed that a separate carrier could
`50
`be used for the flavoring agent, such as a clay, and that
`a smoke-forming agent, such as glycerol, could be ad
`mixed with the flavoring agent. Siegel's proposed ciga
`rette substitute would be coated with a concentrated
`sugar solution to provide an impervious coat and to
`55
`force the hot gases and flavoring agents to flow toward
`the mouth of the user. It is believed that the presence of
`the flavoring and/or smoke-forming agents in the fuel
`of Siegel's article would cause substantial thermal deg
`radation of those agents and an attendant off-taste.
`60
`Moreover, it is believed that the article would end to
`produce substantial sidestream smoke containing the
`aforementioned unpleasant thermal degradation prod
`licts.
`Another such article was described by Ellis et al. in
`65
`U.S. Pat. No. 3,258,015. Ellis et al. proposed a smoking
`article which has an outer cylinder of fuel having good
`smoldering characteristics, preferably fine cut tobacco
`
`4,793,365
`2
`or reconstituted tobacco, surrounding a metal tube con
`taining tobacco, reconstituted tobacco, or other source
`of nicotine and water vapor. On smoking, the burning
`fuel heated the nicotine source material to cause the
`release of nicotine vapor and potentially aerosol gener
`ating material, including water vapor. This was mixed
`with heated air which entered the open end of the tube.
`A substantial disadvantage of this article was the ulti
`mate protrusion of the metal tube as the tobacco fuel
`was consumed. Other apparent disadvantages of this
`proposed smoking article include the presence of sub
`stantial tobacco pyrolysis products, the substantial to
`bacco sidestream smoke and ash, and the possible pyrol
`ysis of the nicotine source material in the metal tube.
`In U.S. Pat. No. 3,356,094, Ellis et al. modified their
`original design to eliminate the protruding metal tube.
`This new design employed a tube made out of a mate
`rial, such as certain inorganic salts or an epoxy bonded
`ceramic, which became frangible upon heating. This
`frangible tube was then removed when the smoker
`eliminated ash from the end of the article. Even though
`the appearance of the article was very similar to a con
`ventional cigarette, apparently no commercial product
`was ever marketed.
`In U.S. Pat. No. 3,738,374, Bennett proposed the use
`of carbon or graphite fibers, mat, or cloth associated
`with an oxidizing agent as a substitute cigarette filler.
`Flavor was provided by the incorporation of a flavor or
`fragrance into the mouthend of an optional filter tip.
`U.S. Pat. Nos. 3,943,941 and 4,044,777 to Boyd et al.
`and British Patent No. 1,431,045 proposed the use of a
`fibrous carbon fuel which was mixed or impregnated
`with volatile solids or liquids which were capable of
`distilling or subliming into the smoke stream to provide
`"smoke' to be inhaled upon burning of the fuel. Among
`the enumerated smoke producing agents were polyhyd
`ric alcohols, such as propylene glycol, glycerol, and 1,3
`butylene glycol, and glyceryl esters, such as triacetin.
`Despite Boyd et al.'s desire that the volatile materials
`distill without chemical change, it is believed that the
`mixture of these materials with the fuel would lead to
`substantial thermal decomposition of the volatile mate
`rials and to bitter offtastes. Similar products were pro
`posed in U.S. Pat. No. 4,286,604 to Ehretsmann et al.
`and in U.S. Pat. No, 4,326,544 to Hardwick et al.
`Bolt et al., in U.S. Pat. No. 4,340,072 proposed a
`smoking article having a fuel rod with a central air
`passageway and a mouthend chamber containing an
`aerosol forming agent. Tee fuel rod preferably was a
`molding or extrusion of reconstituted tobacco and/or
`tobacco substitute, although the patent also proposed
`the use of tobacco, a mixture of tobacco substitute mate
`rial and carbon, or a sodium carboxymethycellulose
`(SCMC) and carbon mixture. The aerosol forming
`agent was proposed to be a nicotine source material, or
`granules or microcapsules of a flavorant in triacetin or
`benzyl benzoate. Upon burning, air entered the air pas
`sage where it was mixed with combustion gases from
`the burning rod. The flow of these hot gases reportedly
`ruptured the granules or microcapsules to release the
`volatile material. This material reportedly formed an
`aerosol and/or was transferred into the mainstream
`aerosol. It is believed that the articles of Bolt et al., due
`in part to the long fuel rod, would produce insufficient
`aerosol from the aerosol former to be acceptable, espe
`cially in the early puffs. The use of microcapsules or
`granules would further impair aerosol delivery because
`
`Philip Morris Products, S.A.
`Exhibit 1011
`Page 005
`
`

`

`4,793,365
`4.
`3
`which maximizes heat transfer to the aerosol generating
`of the heat needed to rupture the wall material. More
`means and the resultant production of aerosol. The use
`over, total aerosol delivery would appear dependent on
`of a relatively short, low mass aerosol generating body,
`the use of tobacco or tobacco pyrolysis products and
`in close proximity to the short fuel element, also in
`sidestream smoke which would not be desirable in this
`creases aerosol production by minimizing the heat sink
`type smoking article.
`effect of the substrate or carrier. Because the aerosol
`U.S. Pat. No. 3,516,417 to Moses proposed a smoking
`forming substance is physically separate from the fuel
`article, with a tobacco fuel, which was identical to the
`element, it is exposed to substantially lower tempera
`article of Bolt et al., except that Moses used a double
`tures than are present in the burning fire cone, which
`density plug of tobacco in lieu of the granular or micro
`minimizes the possibility of thermal degradation of the
`encapsulated flavorant of Bolt et al. See FIG. 4, and col.
`10
`aerosol former. Moreover, the use of a carbonaceous
`4, 1. 17-35. This article would suffer many of the same
`fuel element which is substantially free of volatile or
`problems as the articles proposed by Bolt et al.
`ganic material eliminates the presence of substantial
`Thus, despite decades of interest and effort, there is
`pyrolysis or incomplete combustion products and the
`still no smoking article on the market which provides
`presence of substantial sidestream smoke.
`the benefits and advantages associated with conven
`15
`In another important aspect of the present invention,
`tional cigarette smoking.
`the smoking article is provided with means for conduct
`SUMMARY OF THE INVENTION
`ing heat from the fuel element to the aerosol generating
`The present invention relates to a smoking article
`means other than the mere end to end abutment of the
`fuel element to the aerosol generating means. Prefera
`which is capable of producing substantial quantities of 20
`bly, the heat conducting means is a heat conducting
`aerosol, both initially and over the useful life of the
`product, without significant thermal degradation of the
`member, such as a metal foil, or a metal rod, which
`advantageously contacts both the fuel element and the
`aerosol former and without the presence of substantial
`aerosol generating means. Contact of the metal foil is
`pyrolysis or incomplete combustion products or side
`preferably along the external longitudinal surfaces of
`stream smoke. Thus, the article of the present invention
`25
`the fuel element and the aerosol generator. Contact of
`is able to provide the user with the sensations and bene
`the metal rod is preferably made by embedding the rod
`fits of cigarette smoking without burning tobacco.
`centrally within the fuel element and the aerosol gener
`In one aspect of the present invention, the smoking
`article has a short, combustible carbonaceous fuel ele
`atOr.
`The use of the heat conducting means of the present
`ment, generally less than about 30 mm long, which is
`invention substantially increases heat transfer to the
`substantially free of volatile organic material. Prefera
`aerosol generator which, in turn, volatilizes larger
`bly, the fuel element is less than about 15 mm in length.
`quantities of the aerosol former for delivery to the user.
`A physically separate aerosol generating means, such as
`This increased heat transfer is, in part, due to the fact
`a substrate or chamber containing an aerosol forming
`that the heat conducting means transfers heat both dur
`substance, is located in a conductive heat exchange
`ing a puff and during smolder, whereas convective heat
`relationship to the fuel element. preferably, the heat
`transfer, which is primarily relied upon in most prior art
`exchange relationship is achieved by providing a heat
`aerosol generating articles, primarily delivers heat only
`conductive member which efficiently conducts or
`during a puff. This increased heat transfer makes more
`transfers heat from the burning fuel element to the aero
`efficient use of the available fuel energy, reduces the
`sol generating means. Advantageously, the aerosol gen
`erating means is a relatively short body, again generally
`amount of fuel needed, helps deliver aerosol on the
`initial puffs, and substantially reduces material costs of
`less than about 30 mm long, which either abuts or is
`the fuel. Further, it is believed that conductive heat
`adjacent to the nonlighting end of the fuel element.
`transfer reduces the carbon fuel combustion tempera
`Preferably, the aerosol generating means is a thermally
`ture and thus greatly reduces the CO/CO2 ratio.
`stable substrate impregnated with one or more aerosol
`In a particularly preferred embodiment of the inven
`forming substances and is less than about 15 mm in
`length.
`tion, the fuel element is a pressed carbon plug or mass of
`carbonized fibers, generally about 10 mm or less in
`The smoking article of the present invention nor
`length, which is provided with at least one longitudinal
`mally is provided with mouthend piece including
`passage to aid heat transfer to the aerosol generator.
`means, such as a longitudinal passage, for delivering the
`The aerosol generating means is a thermally stable,
`volatile material produced by the aerosol generating
`preferably carbonaceous substrate about 10 mm or less
`means to the user. Advantageously, the article has the
`in length which is impregnated with one or more aero
`same overall dimensions as a conventional cigarette,
`sol forming substances, such as a mixture of glycerol
`and as a result, the mouthend piece and the aerosol
`and propylene glycol. This substrate may be provided
`delivery means usually extend over more than one-half 55
`with an axial passage which may be aligned with an
`the length of the article. Alternatively, the fuel element
`axial passage in the fuel element. This fuel element and
`and the aerosol generating means may be produced
`substrate are joined by an encircling piece of heat con
`without a built-in mouthpiece or aerosol delivery
`ductive aluminum foil which envelops the longitudinal
`means, for use as a disposable cartridge, with a separate,
`periphery of the nonlighting end of the fuel element and
`reusable mouthpiece.
`at least a portion, and preferably all, of the longitudinal
`Upon lighting, the fuel element generates heat which
`periphery of the substrate.
`is used to volatilize the aerosol forming substance or
`Preferred embodiments of the invention are capable
`substances contained in the substrate or chamber. These
`of delivering at least 0.6 mg of aerosol, measured as wet
`volatile materials are then drawn toward the mouthend,
`total particulate matter, in the first 3 puffs, when
`especially during puffing, and into the user's mouth,
`65
`smoked under standard FTC smoking conditions. More
`akin to the smoke of a conventional cigarette. Because
`preferably, preferred embodiments of the invention are
`the fuel element is relatively short, the hot, burning fire
`capable of delivering 1.5 mg or more of aerosol in the
`cone is always close to the aerosol generating body,
`
`30
`
`35
`
`45
`
`50
`
`Philip Morris Products, S.A.
`Exhibit 1011
`Page 006
`
`

`

`10
`
`15
`
`4,793,365
`5
`6
`first 3 puffs. Most preferably, preferred embodiments of
`series of peripheral grooves 24 which provide passages
`the invention are capable of delivering 3 mg or more of
`between the disc and the foil lined tube 14.
`The foil lined paper tube 14, which forms the mouth
`aerosol in the first 3 puffs when smoked under standard
`FTC smoking conditions. Moreover, preferred embodi
`end of the article, surrounds aerosol generating means
`12 and the rear, non-lighting end of fuel element 10. The
`ments of the invention deliver an average of at least 5
`about 0.8 mg of wet total particulate matter per puff
`tube also forms an aerosol delivery passage 26 between
`the aerosol generating means 12 and the mouthend 15 of
`under standard FTC smoking conditions.
`The smoking article of the present invention also may
`the article.
`The article illustrated in FIG. 1 also includes an op
`include a charge or plug of tobacco which is used to add
`tional mass or plug of tobacco 28 to contribute flavor to
`a tobacco flavor to the aerosol. Preferably, the tobacco
`the aerosol. This tobacco charge 28 may be placed at
`is placed at the mouthend of the aerosol generating
`the mouthend of disc 22, as shown in FIG. 1, or it may
`means, or it is mixed with the carrier for the aerosol
`be placed between glass beads 20 and disc 22. It also
`forming substance. Flavoring agents also may be incor
`may be placed in passage 26 at a location spaced from
`porated into the article to flavor the aerosol delivered to
`aerosol generator 12.
`the user.
`In the embodiment shown in FIG. 2, the short fuel
`The smoking article of the present invention also
`element 10 is a pressed carbon rod or plug, about 20 mm
`provides an aerosol "smoke" which is chemically sim
`long, which is provided with an axial hole 16. Alterna
`ple, consisting essentially of air, oxides of carbon, water,
`tively, the fuel ma beformed from carbonized fibers and
`and the aerosol which carries any desired flavorants or
`preferably also provided with an axial passageway cor
`20
`other desired volatile materials, and trace amounts of
`responding to hole 16. In this embodiment, aerosol
`other materials. The aerosol "smoke' has no significant
`generating means 12 includes athermally stable conduc
`mutagenic activity using the Ames test discussed here
`tive carbonaceous substrate 30, such as a plug of porous
`inafter. In addition, the article may be made virtually
`carbon, which is impregnated with an aerosol forming
`ashless so that the user does not have to remove any ash
`substance or substances. This substrate may be provided
`25
`during use.
`with an optional axial passageway 32, as is shown in
`In another important aspect of the invention, the
`FIG. 2. This embodiment also includes a mass of to
`aerosol forming substance may be replaced, in whole or
`bacco 28 which is preferably placed at the mouthend of
`in part, by a volatile, nonaerosol substance, such as a
`substrate 30. For appearance sake, this article also in
`flavoring agent and/or other volatile solid or liquid
`cludes an optional high porosity cellulose acetate filter
`30
`materials, to deliver flavors and/or other materials to
`34, which may be provided with peripheral grooves 36
`the user, in aerosol or vapor form.
`to provide passages for the aerosol forming substance
`The smoking article of the present invention is de
`between filter 34 and foil tube 14. Optionally, as shown
`scribed in greater detail in the accompanying drawings
`in FIG. 2A, the lighting end 11 of the fuel element may
`and in the detailed description of the invention which
`be tapered to improve lightability.
`35
`Upon lighting any of the aforesaid embodiments, the
`carbonaceous fuel element 10 burns, which generates
`the heat used to volatilize the aerosol forming substance
`or substances present in aerosol generating means 12.
`These volatile materials are then drawn down passage
`26 toward the mouthend 15, especially during puffing,
`and into the user's mouth, like the smoke of a conven
`tional cigarette. Because the aerosol forming substance
`is physically separate from the fuel element, it is ex
`posed to substantially lower temperatures than are pres
`ent in the burning fire cone, which minimizes the possi
`bility of thermal degradation of the aerosol former. This
`also results in aerosol production during puffing, but
`little or no aerosol production during smolder. In addi
`tion, the use of a carbonaceous fuel element and a physi
`cally separate aerosol generator eliminate the presence
`of substantial pyrolysis or incomplete combustion prod
`ucts and avoid the production of substantial sidestream
`smoke.
`If a charge of tobacco is employed, the hot vapors of
`the aerosol former are swept through the bed of to
`bacco to extract and vaporize the volatile components
`in the tobacco, without the need for tobacco combus
`tion. Thus the user of this smoking article receives an
`aerosol which contains the qualities and flavors of natu
`ral tobacco without the combustion products produced
`by a conventional cigarette.
`Because of the small size and burning characteristics
`of the carbonaceous fuel elements employed in the pres
`ent invention, the fuel element usually begins burning
`over substantially all of its exposed length within a few
`puffs. Thus, the portion of the fuel element adjacent to
`the aerosol generator 12 becomes hot quickly, which
`
`follows.
`-
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIGS. 1 through 9 are longitudinal, sectional views
`of various embodiments of the invention;
`40
`FIG. 1A is a sectional view of the embodiment of
`FIG. 1, taken along lines 1A-1A in FIG. 1;
`FIG. 2A is a longitudinal view of a modified, tapered
`fuel element of the embodiment of FIG. 2;
`FIG. 3A is a sectional view of the embodiment of 45
`FIG. 3, taken along lines 3A-3A in FIG. 3; and
`FIG. 10 is the average peak temperature profile of the
`smoking article of Example 5 during use.
`DETAILED DESCRIPTION OF THE
`INVENTION
`The embodiment of the invention illustrated in FIG.
`1, which preferably has the diameter of a conventional
`cigarette, includes a short, combustible carbonaceous
`fuel element 10, an abutting aerosol generating means
`55
`12, and a foil lined paper tube 14, which forms the
`mouthend 15 of the article. In this embodiment, fuel
`element 10 is a blow pipe charcoal, a carbonized wood,
`which is provided with five longitudinally extending
`holes 16. See FIG. A. The fuel element 10, which is 60
`about 20 mm long, optionally may be wrapped with
`cigarette paper to improve lighting of the charcoal fuel.
`This paper may be treated with known burn additives.
`Aerosol generating means 12 includes a plurality of
`glass beads 20 coated with an aerosol forming substance 65
`or substances, such as glycerin. The glass beads are held
`in place by a porous disc 22, which may be made of
`cellulose acetate. This disc may be provided with a
`
`50
`
`Philip Morris Products, S.A.
`Exhibit 1011
`Page 007
`
`

`

`O
`
`15
`
`4,793,365
`8
`7
`has at least one, preferably from 2 to 5, peripheral
`significantly increases heat transfer to the aerosol gener
`grooves 96 therein, to allow air passage through the
`ator, especially during the early and middle puffs. Be
`substrate The article of FIG. 3 has the advantage that
`cause the fuel element is so short, there is never a long
`the air introduced into the void space 97 contains less
`section of nonburning fuel to act as a heat sink, as in the
`carbon oxidation products because it is not drawn
`prior art thermal aerosol articles. Heat transfer, and
`through the burning fuel.
`therefore aerosol delivery, also is enhanced by the use
`In general, the combustible carbonaceous fuel ele
`of holes 16 through the fuel, which draw hot gases to
`ments which may be employed in practicing the inven
`the aerosol generator, especially during puffing.
`tion are generally less than about 30 mm long. Advanta
`The presence of fill lined tube 14, which couples the
`geously the fuel element is about 20 mm or less in
`nonlighting end of fuel 10 to aerosol generator 12, also
`length, preferably about 15 mm or less in length. In
`increases heat transfer to the aerosol generator. The foil
`most current preferred embodiments, the fuel element is
`also helps to extinguish the fire cone. When only a small
`between about 3 mm to about 10 mm in length. These
`amount of the unburned fuel remains, heat loss through
`lengths are sufficient to provide fuel for at least about 7
`the foil acts as a heat sink which helps to extinguish the
`to 10 puffs, the normal number of puffs obtained with a
`fire cone.
`conventional cigarette under FTC smoking conditions.
`The foil used in this article is typically an aluminum
`Preferably, the feel is provided with means for passing
`foil of 0.35 mils (0.0089 mm) in thickness, but the thick
`hot gases to the substrate, such as one or more longitu
`ness and/or the type of metal employed may be varied
`dinally extending holes 16 in FIGS. 1 and 2. It is be
`to achieve any desired degree of heat transfer. Other
`lieved the holes also aid in decreasing heat transfer in
`types of heat conducting members such as Grafoil,
`20
`later puffs by increasing in size.
`available from Union Carbide, also may be employed.
`The fuel elements are primarily formed of a carbona
`In the foregoing embodiments of the invention, short
`ceous material. Preferably, the carbon content of the
`fuel element 10, foil lined tube 14, and passages 16 in the
`fuel is at least 80%, most preferably about 90% or more,
`fuel cooperate with the aerosol generator to provide a
`by weight. High carbon content fuels are preferred
`system which is capable of producing substantial quanti
`25
`because they produce minimal pyrolysis and incomplete
`ties of aerosol throughout the life of the fuel element,
`combustion products, little or no visible sidestream
`and especially during the early and middle puffs. The
`smoke, minimal ash, and high heat capacity. However,
`close proximity of the fire cone to the aerosol generator
`lower carbon content fuel elements are within the scope
`after a few puffs, together with the conductive metallic
`of this invention, especially where a nonburning inert
`foil, results in heat delivery during puffs and during the
`30
`relatively long period of smolder between puffs. Stan
`filler is used.
`The carbonaceous materials used in or as the fuel may
`dard FTC smoking conditions consist of two second
`be derived from virtually any of the numerous carbon
`puffs separated by 58 seconds of smolder.) While not
`sources known to those skilled in the art. Preferably, the
`wishing to be bound by theory, it is believed that the
`carbonaceous material is obtained by the pyrolysis or
`aerosol generator is maintained at relatively high ten
`35
`carbonization of cellulosic materials, such as wood,
`peratures between puffs and that the additional heat
`cotton, rayon, tobacco, coconut, paper, and the like,
`delivered during puffs, which is significantly increased
`although carbonaceous materials from other sources
`by the hole or holes 16 in the fuel element, is primarily
`may be used.
`utilized to vaporize the aerosol forming substance. This
`In most instances, the carbonaceous material should
`increased heat transfer makes more efficient use of the
`be capable of being ignited by a conventional cigarette
`available fuel energy, reduces the amount of fuel
`lighter without the use of an oxidizing agent. Burning
`needed, and helps deliver aerosol on the initial puffs.
`characteristics of this type may generally be obtained
`Further, the conductive heat transfer utilized in the
`from a cellulosic material which has been pyrolyzed at
`present invention is believed to reduce the carbon fuel
`temperatures between about 400 C. to about 1000 C.,
`combustion temperature which, it is believed, reduces
`45
`preferably between about 500 C. to about 950 C., in an
`the CO/CO2 ratio in the combustion products produced
`inert atmosphere or under a vacuum. The pyrolysis time
`by the feel. See, e.g., C. Hagg, General Inorganic Chem
`is not believed to be important, as long as the tempera
`istry at p. 592 (John Wiley & Sons, 1969).
`ture at the center of the pyrolyzed mass has reached the
`The embodiment of the invention illustrated in FIG.
`aforesaid temperature range for at least a few minutes.
`3, includes a short combustible carbonaceous fuel ele
`50
`While undesirable in most cases, carbonaceous mate
`ment 10, connected to aerosol generating means 12 by a
`rials which require the use of an oxidizing agent to
`heat conductive rod 99 and by a foil lined paper tube 14,
`render them ignitable by a cigarette lighter are within
`which also forms the mouthend 15 of the article. In this
`the scope of this invention, as are carbonaceous materi
`embodiment, fuel element 10 may be blowpipe charcoal
`als which require the use of a glow retardant or other
`or a pressed or extruded carbon rod or plug or other
`type of combustion modifying agent. Such combustion
`carbonaceous fuel source.
`modifying agents are disclosed in many prior art patents
`Aerosol generating means 12 includes a thermally
`and publications and are known to those of ordinary
`stable carbonaceous substrate 30, such as a plug of po
`rous carbon, which is impregnated with an aerosol
`skill in the art.
`The carbonaceous fuel elements used in practicing
`forming substance or substances. This embodiment in
`60
`the invention are substantially free of volatile organic
`cludes a void space 97 between the fuel element 10 and
`material. By that, it is meant that the fuel element is not
`the substrate 30. The portion of the foil lined tube 14
`impregnated or mixed with substantial amounts of vola
`surrounding this void space includes a plurality of pe
`tile organic materials, such as volatile aerosol forming
`ripheral holes 100 which permit sufficient air to enter
`the void space to provide appropriate pressure drop.
`or flavoring agents, which could degrade at the com
`65
`bustion temperatures of the fuel. Ho