Cigarette sidestream smoke and free-burn rate control device

Information

  • Patent Grant
  • 6748955
  • Patent Number
    6,748,955
  • Date Filed
    Friday, February 15, 2002
    22 years ago
  • Date Issued
    Tuesday, June 15, 2004
    20 years ago
Abstract
A device for minimizing cigarette sidestream smoke and reducing free-burn rate of a burning cigarette is disclosed. The device comprises a non-combustible tubular element encasing an effective length of a tobacco charge of a cigarette located in the tubular element. The tubular element minimizes sidestream smoke emission from a burning tobacco charge and reduces free-burn rate of such burning tobacco charge to increase the number of puffs from the burning tobacco charge.
Description




SCOPE OF THE INVENTION




The invention relates generally to an apparatus which is to be used in combination with a cigarette or other tobacco product to control sidestream smoke and increase the numer of puffs available to the smoker from a given amount of tobacco. The apparatus will permit, for instance, using only as much tobacco as necessary to deliver in a much thinner cigarette of lesser diameter, an increased yield of mainstream smoke from the burning tobacco and conventional taste while significantly reducing sidestream smoke. Unlike a conventional sigarette which involves considerable tobacco waste as the thicker cigarette is burned to produce sidestream smoke, the use of the thinner cigarette with this apparatus converts what would be normally tobacco wasted on sidestream smoke into mainstream smoke.




Simply stated, the apparatus includes a tube having a predetermined porosity into which a tobacco product, such as a cigarette is inserted. Preferably, there is a space between the outside of the cigarette and the inside of the tube. The porosity of the tube is carefully selected to achieve sidestream smoke reduction and reduction of free-burn rate between puffs. A very thin cigarette may be inserted and smoked for the same number of puffs as a conventional cigarette, with the resultant saving of tobacco and other cigarette materials and a significant reduction of sidestream smoke. The tube may include a catalytic material to treat sidestream smoke constituents.




The apparatus will be discussed in greater detail and can be used in various different ways, for instance, rather than a cigarette, a tobacco charge that cannot be separately smoked, is inserted and, by controlling the holes and porosity of the tube, could be smoked. It is apparent that all the conventional quality requirements in making a cigarette, such as, firmness and end fallout are no longer of priority with this invention.




While the apparatus could be sized for use with a conventional cigarette, an advantage is that a thin cigarette can be inserted and smoked with the same smoking characteristics as if it were a conventional sized cigarette.




BACKGROUND OF THE INVENTION




When smoking in a conventional manner, there is generally understood to be three types of cigarette smoke, mainstream smoke, exhaled smoke and sidestream smoke. There has been significant interest in reducing the amount of sidestream smoke emitted by a burning cigarette or cigar because it accounts for the majority of smoke emitted during the smoking process. Attempts have been made to control sidestream smoke by one or more of the following techniques:




1) alter the tobacco composition and packing characteristics of the tobacco rod or charge in the cigarette or cigar;




2) alter the wrapping for the cigarette or cigar;




3) alter the diameter of the cigarette as well as its tobacco composition; and/or




4) provide a device on the cigarette or cigar to contain and/or contaol sidestream smoke emissions.




Various cigarette tobacco and cigarette paper formulations have been suggested which in one way or another affect the free-burn rate of the cigarette or cigar with a view to reducing sidestream smoke and/or achieving an extinguishment of the lit cigarette or cigar when left idle over an extended period of time. Such designs include a judicious selection of tobacco blends, density and multiple layers of cigarette tobacco in the tobacco charge. Such selected designs can appreciably retard the free-burn rate of the cigarette and hence, increase the number of puffs obtained per unit length of cigarette. Either in combination with tobacco selection and/or construction or independently of the tobacco make up, various cigarette paper compositions can also affect free-burn rate of the cigarette. Such paper compositions include the use of chemicals to retard free-burn rate, multiple wrappings of different types of cigarette paper of the same or different characteristics and reduction of air permeability. See for example, Canadian Patent 1,259,008 and U.S. Pat. Nos. 4,878,507 and 4,915,117.




Various devices have been provided which contain the cigarette, primarily for purposes of preventing accidental fires. They may or may not at the same time include various types of filters to filter and thereby reduce the amount of sidestream smoke. Examples of such devices are shown in U.S. Pat. Nos. 1,211,071; 3,827,444 and 4,685,477.




Further, various types of cigarette holders have been made available which service the primary feature of minimizing staining of the smoker's fingers. Such devices may be connected to the cigarette tip and/or mounted on the cigarette, such as shown in U.S. Pat. No. 1,862,679. Other types of cigarettes which are enclosed in wrappers which are perforated in one way or another to provide for safety features and/or control of sidestream smoke are described in Canadian Patent 835,684 and U.S. Pat. Nos. 3,220,418 and 5,271,419.




Devices which are mountable on the cigarette and which may be slid along the cigarette to control combustion and hence free-burn rate are described in U.K. Patent 928,089; U.S. Pat. No. 4,638,819 and International application WO96/22031. The U.K. patent describes a combustion control device for cigarettes by limiting the flow of air to the cigarette burning ember. By retarding combustion of the cigarette, it is suggested that only half of the conventional amount of tobacco need be incorporated in the cigarette and result thereby in a shorter cigarette. The air flow limiting device may be provided by an array of apertures in the device with variable opening or by crimped portions in the device providing longitudinal openings along part of the cigarette. U.S. Pat. No. 4,638,819 describes a ring which is placed on the cigarette and slid therealong during the smoking process to control the free-burn rate of the cigarette and reduce sidestream smoke. The ring is of solid material, preferably metal, which causes considerable staining and due to variable cigarette diameters cannot reliably provide the desired degree of sidestream smoke reduction and extinguishing times.




An alternative ring system is described in applicant's published PCT application WO 96/22031. The device is provided with an inner ring which surrounds and contacts a conventional cigarette perimeter where the inner ring is of porous material. The outer ring encases the inner ring to direct air flow along the length dimension of the porous inner ring. The tortuous paths in the porous material of the inner ring controls the rate of air diffusion to the lit cigarette coal and thereby controls the free-burn rate of the cigarette. The porous material enhances the control of sidestream smoke emitted by the lit cigarette. The device may optionally extend up to one-half the length of the cigarette where air would have to flow along the inner porous ring to the burning coal.




Other systems which have been designed to control sidestream smoke are described in published PCT application WO 95/34226 and U.S. Pat. No. 5,592,955 issued Jan. 14, 1997 and U.S. Pat. No. 5,105,838 issued Apr. 21, 1992. These references describe various tubular configurations in which a tobacco element is placed in an attempt to minimize cigarette sidestream emission.




Although these approaches may have met with various degrees of success, in controlling sidestream smoke emissions, there are problems with some of the devices in providing conventional taste and flavour, ease of use, ease of manufacture, streamline appearance and significant reductions in the amount of tobacco used. The various embodiments of this invention provide a device which overcomes a number of the above problems by controlling both sidestream smoke and free-burn rate while achieving taste, flavour and constituent deliveries comparable to conventional cigarettes. The device of this invention permits the smoking of a thinner cigarette which has only as much tobacco as is necessary to deliver the desired taste while achieving the conventional number of puffs.




In order to facilitate the description of the invention, the term tobacco charge shall be used in referencing a cigarette, cigar, cigarillo, tobacco rod in a porous mesh, a tobacco plug or wrapped tobacco or the like. It is also understood that where the term cigarette is used, it is interchangeable with cigar, cigarillo and the like.




SUMMARY OF THE INVENTION




In accordance with an aspect of the invention, a device for minimizing cigarette sidestream smoke and reducing free-burn rate of a burning cigarette in combination with a filter tip,




A) said device comprising:




i) a non-combustible porous tubular element encasing an effective length of a tobacco charge of a cigarette located in said tubular element, said tubular element having an open end adjacent a distal end of said cigarette to permit lighting of the cigarette distal end and to permit ingress of air; and




ii) said tubular element having a predetermined porosity along at least its length which encases said effective length of said tobacco charge for both minimizing sidestream smoke emission from a burning tobacco charge and reducing free-burn rate of such burning tobacco charge to increase number of puffs from such burning tobacco charge, where said predetermined porosity for said tubular element:




a) retains around a burning ember of said cigarette oxygen deprived combustion gases within said tubular element to reduce rate of combustion and minimizes release of smoke particles through said porous tubular element; and




b) restricts inward flow of air to reduce free-burn rate of said cigarette; and




B) said filter tip comprising an inlet end and an outlet end, said inlet end having an annular sleeve with a central bore to receive an end of said cigarette, said annular sleeve having an outer shoulder onto which said tubular element is friction fitted, said central bore being in communication with a first inner tube of a first filter material, said tube having a closed end opposite its end in communication with said sleeve central bore, an annular space being provided outside of said first tube, a filter plug provided downstream of said annular space and filling said outlet end of said filter tip, a plenum between said filter plug and said first tube for transferring filter smoke from said annular space to said filter plug.




The openings in the tubular element in forming the predetermined porosity may take on various shapes such as narrow slits, slots or pores where the slits and/or slots may be covered with a porous matt of carbon fibre, glass fibre, ceramic fibre, high temperature plastic fibre, metal fibre and the like. The pores may be fabricated in the tubular wall of the element such as by punching to form fibrous projections within the tube where such projections may be relied on to center a cigarette in the tubular element. Alternatively, the tubular element may comprise a body portion of porous materials which perform the functions of retaining at least some of the oxygen deprived combusion gases within the tube and restrict inward flow of air to reduce free-burn rate of the cigarette.




In accordance with another alternative, the tubular element may be of a heat treated ceramic material which is rendered porous by the heat treatment. The makeup of the ceramic precursor material and the heat treating are carried out in a manner to provide the desired predetermined porosity.




In any of the above devices it is understood that the cigarette may be sufficiently thin to provide an overall dimension for the device which is that of a normal cigarette. The thin cigarette may have a diameter ranging from about 4 to 8 mm and preferably, about 4 to 6 mm and most desirably, about 4 mm. A catalytic material may be incorporated in the tubular element particularly when formed from ceramic. The catalytic material may either be coated on the tubular element or may be activated in the tubular element during heat treating of the ceramic precursor. The catalyst may be selected from a variety of well known groups including those which are based on precious metals and rare earth metals and in particular, based on platinum or cerium.











BRIEF DESCRIPTION OF THE DRAWINGS




Various aspects of the invention are shown in the drawings wherein:





FIG. 1

is a perspective view of the preferred embodiment of this invention showing the device in which a cigarette tobacco charge is encased;





FIG. 2

is a section along the device of

FIG. 1

;





FIG. 3

is a section along the lines


3





3


of

FIG. 1

;





FIG. 4

is the enlarged view of an end view of the device;





FIG. 5

is a perspective view of an alternative embodiment of this invention showing the device encasing a tobacco charge of a cigarette;





FIG. 6

is a section along an alternate device;





FIG. 7

is an exploded view of the reusable device;





FIG. 8

is a perspective view of the device with a mouthpiece or tip;





FIG. 9

is an exploded view of an alternate device;





FIG. 10

is a section of an end of the device;





FIG. 11

is an exploded end view of the device of

FIG. 10

;





FIG. 12

is a longitudinal section of an alternative structure for the device of

FIG. 1

;





FIG. 13

is a longitudinal section of an alternative embodiment for the device of

FIG. 12

;





FIG. 14

is a perspective view of an alternative spiral wrap construction for the tubular member;





FIG. 15

is a longitudinal section of the spiral construction of

FIG. 14

;





FIG. 16

is a longitudinal section of an alternative construction for the spiral configuration of

FIG. 14

;





FIG. 17

is a plan view of the device with a temperature indicator;





FIG. 18

is an exploded view of a cigarette tip adapted to fit a holder with detent;





FIG. 19

is a cross-section through an alternative embodiment for the tubular element;





FIG. 20

is a perspective view of an alternative embodiment for the tubular element;





FIG. 21

is a section of

FIG. 26

;





FIG. 22

is a longitudinal section view of an alternative embodiment for the tubular element having a porous wrap of ceramic sheet;





FIG. 23

is an exploded view of an alternative embodiment for the filter tip;





FIG. 24

is a section through the assembled device of

FIG. 23

; and





FIG. 25

is a perspective view of an injection molded component of the device of FIG.


23


.











DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS




The device in accordance with this invention for minimizing sidestream smoke from a tobacco charge such as in a cigarette while controlling free-burn rate, has many features and advantages. The device, which in essence by encasing a tobacco charge, has a low ignition propensity to provide significant safety features should the lit charge be accidentally set down on ignitable materials. The device minimizes sidestream smoke emitted from the tobacco charge due in part to the free-burn rate control aspect of the device. This device has the surprising benefit of providing sidestream smoke control and free-burn rate control while encasing the tobacco charge, yet is capable at the same time of providing all of the normal features in smoking a conventional cigarette such as appearance, feel, taste and flavour. Catalytic materials may be incorporated in or coated on the device to promote further combustion of various gases to avoid any off smell from the device as a cigarette is burning therein.




The device also permits the use of a non-conventional thin cigarette which is considerably thinner than a conventional cigarette and may contain up to ⅔ less tobacco in the tobacco charge, hence, very significant tobacco and material cost savings in the manufacture of cigarettes to be used with the device. More particularly, a very thin or slim cigarette which is non-conventional in the reduced number of puffs and involving significantly ⅔ less tobacco, may be used. The device with the thin non-conventional cigarette provides the smoker with normal inhale pressures, normal quantities of inhaled smoke, normal flavour and taste and normal number of puffs. The thin non-conventional cigarette cannot offer all of these features together if smoked without the device.




An unexpected advantage which flows from the use of a thin non-conventional cigarette for use in this device is that the smaller diameter of the thin cigarette ensures proper burning during the idle phase to avoid off-taste. The device in controlling free-burn rate ensures that the lit cigarette during the idle phase considerably slows down the rate of advance of the burning coal. By virtue of the smaller diameter for the thin non-conventional cigarette, the burning coal extends across the face or the cross-section of the smaller diameter cigarette. This is quite different from what happens with a conventional size cigarette when the free-burn rate is controlled. In a conventional cigarette, due to the excessive amount of tobacco in the larger cross-section, the coal burns inwardly of the cigarette central portion during the idle phase and allows condensation of smoke products in the outer portion of the cigarette. This would appear to be a particular result when the prior art types of free-burn rate control devices are used. Unlike that arrangement, the arrangement according to a preferred embodiment of this invention which involves the thin non-conventional cigarette, is that the coal as it extends across the face, ensures proper burning even during the idle phase so that combustion products do not condense in the outer portion of the slim cigarette. When the cigarette is then picked up again for the next puff, the inhale step causes the coal to rise immediately to temperature and advance quickly along the thin cigarette thereby avoiding any off-taste because the coal is immediately up to normal smoking temperature. It is also a feature of the invention, that the thin non-conventional cigarette may be thinner than the normal slim cigarette of about 5.5 mm to 6 mm. The non-conventional cigarette is a novel structure in the marketplace when its diameter is less than 5.5 mm and particularly when less than 5.2 mm. The thin cigarette as preferably used in the device, is non-conventional in terms of number of puffs and size. The size is not only different in respect of diameter but possibly the length as well. The thin cigarette as with a conventional cigarette, has a suitable wrapping which is ideally the usual form of cigarette paper having the usual composition and porosity. The paper may also include common burn rate modifiers to further retard the free-burn rate of the cigarette such as the burn rate modifiers described in U.S. Pat. No. 4,679,575.




A further significant benefit which flows from the use of a thin cigarette in the device is that the excessive tobacco in a conventional sized cigarette burns off as sidestream smoke. With the free-burn rate control of this device, there is minimal waste of tobacco during the idle phase. Instead, what would have been waste in providing sidestream smoke, during the idle phase of a conventional cigarette becomes mainstream smoke on the next puff thereby increasing yield per unit of tobacco.




Some or all of the features of this invention may be attained by one or more of the following embodiments of the invention, as particularly described with reference to the drawings. In

FIG. 1

, the device


10


has a tubular element


12


for encasing a cigarette


14


. The device


12


extends over the effective length of a tobacco charge for the cigarette. Effective portion of the tobacco charge of the cigarette is intended to include the length of a cigarette which would be normally smoked in order for the smoker to achieve the usual number of puffs (normally eight to ten) as per a conventional cigarette. The device


12


, in accordance with this particular embodiment has several openings


16


in its periphery, one of which is shown in FIG.


1


. The opening


16


is preferably a slit extending longitudinally of the device


10


. The opening of the slit


16


supplies air to the burning cigarette to support combustion where along the length of the opening, a component


18


is provided for effecting free-burn rate control while achieving in the same device, that is, simultaneously minimization of the sidestream smoke emitted from the burning cigarette. In conforming with a conventional cigarette, the tubular element


12


has connected thereto or integrally formed therewith a filter tip portion


20


for purposes of filtering in the usual manner mainstream smoke inhaled from the burning cigarette.




As shown in

FIG. 2

, the tubular device


12


encases the cigarette


14


which has a wrapped tobacco rod portion


22


and in accordance with this particular embodiment, a filter tip portion


24


. The device


12


preferably extends from the distal end


26


of the tobacco rod


22


to at least the filter tip line


28


. The slit


16


extends to at least the rearward portion of the effective length of the tobacco rod


22


to ensure that the cigarette continues to burn for at least the number of puffs associated with a conventional cigarette. The cigarette may then be extinguished by smoking the tobacco rod close to the filter tip line


28


or by virtue of the slit terminating forwardly of the tobacco line


28


so that insufficient air reaches the burning end portion of the cigarette and it extinguishes before reaching the filter tip line


28


. The filter tip portion


20


has a bore


30


provided therein to receive snugly the filter tip


24


of the cigarette and thereby support the cigarette as it extends out from the tip


20


. It is appreciated that the cigarette


14


may only have a wrapped tobacco rod


22


and no filter. In this arrangement, the tobacco rod end would be inserted in and supported by the filter tip


20


. The bore


30


of tip


20


, defines a blind hole, so that the hole does not extend through the tip


20


. The tip


20


has a reduced neck portion


32


to define a land


34


over which the tubular element


12


is slid to provide the assembled unit of FIG.


2


. Tipping paper


35


completes the assembly where the land portion


34


may be sealed to prevent air entering the tip


20


from the gap between cigarette and tube. With the inner edge


36


of the tubular element


12


contacting the abutment


38


of the tip


20


, the assembled unit appears seamless and hence, resembles a conventional looking cigarette in the manner shown in FIG.


1


.




By virtue of the tip


20


supporting the cigarette, the tobacco rod portion


22


is positioned substantially concentrically within the tubular element


12


. In accordance with this particular embodiment, the tubular element


12


, as shown in

FIG. 3

, has an inside diameter defined by the interior surface


40


which is spaced from the exterior surface


42


of the cigarette paper periphery. Such spacing defines an annulus or gap


44


extending along the length of the device


10


to the connection of the tubular element


12


with the device tip


20


. The annulus


44


in conjunction with the component


18


in the opening


16


, perform in combination the control aspects required in minimizing sidestream smoke and reducing free-burn rate of the cigarette.




The tubular element


12


is formed of a cigarette smoke impervious material. In order to maintain the structural integrity of the tubular element


12


during the smoking process, the material is non-combustible and is able to withstand the temperatures of a burning coal receding inward along the tubular element during the smoking process. Similarly, the component


18


in the openings


16


is non-combustible to ensure all aspects of sidestream smoke control and free-burn rate control are achieved while smoking the cigarette. The non-combustible aspect of the tubular element


12


also permits re-use of the device for smoking a package of cigarettes, by simply removing the tubular element


12


from the tip


20


and withdrawing the cigarette


14


from the tip


20


. The device is then ready for re-use by inserting a fresh cigarette


14


in the tip


20


and re-assembling the tubular element


12


on the tip


20


. It is understood of course that all cigarettes in the package may come equipped with the device


10


and simply discard the unit when the cigarette is smoked.




As shown in the enlarged view of

FIG. 3

, the slit


16


defines an opening


46


having the component


18


provided therein to effect control of the cigarette free-burn rate and minimize sidestream smoke. Depending upon the shape and size of the slits


16


, a sufficient number are provided along the tubular element


12


to ensure with the components


18


in place that sufficient air reaches the effective portion of a tobacco rod to maintain the desired free-burn rate in providing the usual number of puffs equivalent to a conventional cigarette. The component


18


is preferably of a porous material which is non-combustible. The porous material may be formed from carbon fibre, preferably activated carbon fibre, ceramic fibre, glass fibre, high temperature plastic fibre, metal fibre, synthetic wood derived materials of a porous nature (briar wood) and the like. The fibres may be in long strand form or may also be matted or in some way formed into a matt or sheet and rendered porous by physically making minute pores in the material, (i.e., by laser drilling, by chemical leaching of soluble minute particulars from matt or mild calcining to remove combustibles from the material).




The porous material may be in the form of a matt or sheet and may be woven to provide a degree of porosity which for the number and size of selected slits


16


, provides the necessary control in achieving the desired free-burn rate of the cigarette. The placement of component


18


which may be the porous woven or non-woven, matt or sheet of non-combustible material may be just in the slit


16


as shown. This may be done by dipping the tubular member


12


in a slurry of the fibrous material, which is used to form the matt. Preferably the fibrous material is activated carbon fibre in an aqueous slurry optionally in combination with a suitable binder and possibly catalytic materials. Once the slurry has dried and thereby filling the slits


16


, any excess is removed from the interior surface


40


of the tubular member


12


.




The porous material for the slits may be long strands positioned within the slits instead of being matted or woven into a sheet. This alternative embodiment as it would apply to longitudinally extending slits in the tubular member is shown in FIG.


4


. The tubular element


12


has the longitudinally extending slits


16


filled with a porous material


18


as in the earlier described embodiment of FIG.


1


. The difference however is the composition for the fibrous material


18


, as shown in more detail in FIG.


4


. Instead of a matting, as described with respect to

FIG. 3

, the fibrous material is in the form of longitudinally extending strands


126


which extend along the length of the slit


16


. The strands of material may be of glass, plastic, metal or carbon fibre and the like. Preferably, the strands


126


are of an activated carbon fibre. A sufficient number of strands are located within the slit


16


to define spaces or in essence very long and narrow pores


128


between the strands which perform the necessary dual function of sidestream smoke control and free-burn rate control. Preferably, the strands are of hair-like diameter in order to increase the number which may be provided in the slits and at the same time significantly increasing surface area for the fibrous material to work on the sidestream smoke control while providing an acceptable pressure drop to simulate normal inhale pressures on cigarette. The strands are located along the slit and may be secured at various intervals along the slit to ensure that the strands do not fall out of the slit during packaging or use.




The conventional wisdom in respect of free-burn rate control is to restrict the flow of air to the burning coal of a lit cigarette. By restricting air flow, the free-burn rate of the cigarette is reduced because rate of combustion is retarded. Although this approach has been successful in controlling free-burn rate, such devices may restrict the flow of air when the smoker draws on the cigarette.




The device in accordance with this invention would not however appear to be functioning in a conventional manner for controlling free-burn rate. Although the porous material


18


and/or slits


16


sizing may restrict air flow, the porosity and pore size may be selected such that at least some of the hot oxygen deprived gases of combustion are retained by the tubular element


12


in the annulus region


44


of the burning ember. As shown in

FIG. 2

, the burning cigarette has an ember or coal


21


receding in tube


12


to the position shown in dot. The usual ash cone


27


is behind the advancing ember


21


. The hot combustion gases are located in the annulus or gap


44


as developed by the burning ember such as indicated at


23


and


25


above, below and around the cigarette. At least some, if not substantially all or a majority of the hot gases retained in regions


23


and


25


around the burning ember


21


, is believed due to the selected porosity of the openings


16


and/or the porous material


18


. In controlling sidestream smoke, the porosity and pore sizing is selected to retain preferably a major portion, if not substantially all the hot gases and thereby develop in the region of the ember


21


an oxygen deprived gas. The porosity of the tubular element


12


not only restricts air flow, but as well is believed to contain the hot oxygen deprived combustion gas and thereby starve the burning ember and reduce rate of combustion and hence retard free-burn rate of the cigarette. The porosity of the material is selected to ensure that flow of air into the tube during the idle phase of the cigarette is minimal. This action maintains the level of oxygen deprived gases in the region of the burning coal and thereby keeps the free-burn rate of the cigarette at the desired minimum burn rate. When a smoker draws on the device, air is drawn in through the openings and/or porous material in the tubular element as well through the open end to supply the needed air to support burning during the puff phase. Once the smoker stops drawing on the cigarette, the contained oxygen deprived combustion gases in the region of the burning ember immediately retard rate of combustion and thereby reduce free-burn rate. With this guidance, it is appreciated that the pore sizing in the tube may vary depending on a number of factors including type of tube material physical properties, composition and type of pore openings. It has been demonstrated on a repeated basis that some testing may be required in selecting various pore sizings which provide the necessary tube porosity for controlling free-burn rate and sidestream smoke.




This approach to controlling free-burn rate is quite different from many of the prior art devices which are primarily focused on controlling air flow to the burning ember. The device in accordance with this invention retains the developed hot gases in the region of the burning ember by providing an enlarged region in the annulus to contain the larger volume of hot gases compared to the smaller volume of fresh air needed to support combustion. By providing an annulus of open space or filled with porous material, as will be described with respect to

FIG. 5

, minimal but sufficient volumes of air to support and maintain minimal combustion during free-burn and commencement of puffing on the cigarette are provided. As the puff on the cigarette continues, additional air is drawn through the tubular element openings and also through the tubular element open end.




The porous material also has the capability of adsorbing or absorbing various particulate components and aerosol of the sidestream smoke and capturing such material so that in the event the device is re-used the captured smoke particulates are not released to affect the flavour and taste of a replaced new cigarette to be smoked. The preferred carbon material for the porous material is commonly sold in the form of a mat or sheet which may be matted or woven and thereby facilitates its application to slits


16


in the device


12


. The carbon fibre material may cover the entirety of the tube interior or just cover the slits. Alternatively, the long strands of carbon fibre may be located in and along the slits


16


in a manner to be described with respect to FIG.


4


.




It is appreciated that the openings formed in the tubular element of the embodiment of

FIG. 1

may be formed therein by laser cutting, high speed saw cutting, stamping, punching, piercing and the like. The porous component


18


may be applied to the openings by dipping the tubular element in a slurry of the fibrous material to form a porous fibrous matt in the openings. When the slurry is dried within the tubular element, excess fibrous material within the tubular element may be removed. It is also understood that fibrous material may be precisely positioned in the slit


16


and heated with a laser beam somewhat similar to the manner in which laser printing is accomplished on paper.




The tubular element


12


is formed of a non-combustible material which may preferably be a ceramic, high temperature plastic, treated paper or porcelain paper, synthetic porous wood derived materials or sheet rolled and secured to form the desired size for the tubular element. The interior may be coated with catalytic particles to catalyze oxidation of carbon and nitrogen containing gases given off from the primary burning of tobacco. Preferably, the exterior of the tubular element


12


is white to resemble cigarette paper or when used on a cigar, is a tan colour to resemble a cigar wrapper. Alternatively, the tubular member could be wrapped in a cigarette paper of sufficient porosity. The tip


20


may be a normally constructed filter element of a conventional cigarette with sufficient structural integrity to maintain the bore


30


therein to receive the tip portion


24


of the cigarette


14


. The tip portion


20


may be wrapped in a suitable paper or like material so that the assembled unit of

FIG. 1

looks like a conventional cigarette. It is appreciated that the tip portion


20


, when used with a cigar, may be formed to look like the conventional tip of a cigar or the conventional mouthpiece commonly used with cigars.




The further embodiment of the invention, as shown in

FIG. 5

demonstrates an alternative arrangement for the tubular element


48


of the device


10


. The tubular element


48


encases a cigarette


50


and has a suitable tip


52


. The tubular element


48


is formed from a substantial thickness of non-combustible porous flexible material. The thickness of the porous material is considerably thicker than the thickness of the porous material used in component


18


of the embodiment of FIG.


1


. The porous material may be of the same makeup as the material of component


18


. It may be a sheet or a matt, with pores formed therein or a matted or woven carbon fibre, preferably activated carbon fibre, glass fibre, ceramic fibre, high temperature plastic fibre, metal fibre and the like and may optionally include catalytic particles to enhance continued combustion of gas from the burning tobacco. The tubular component has the porous material


54


extending the length of the tubular element


48


to the filter tip line


56


of the tip


52


. The porous material, as with the embodiment of

FIG. 1

, extends along the tubular element for the effective length of the tobacco rod to be smoked so as to simulate the same conditions in smoking a conventional cigarette. The tip


52


is constructed in a manner similar to the tip


20


of FIG.


1


. The tip


52


has a red portion


58


defining a land


60


with an abutment or stop


62


. The tubular element


48


has an end portion


64


and is dimensioned to abut the land


60


. Tipping paper


65


is used in the conventional manner to complete assembling of the tubular element


48


to the tip


52


. The cigarette


50


fits within the bore


66


in a manner described with respect to FIG.


2


. The cigarette


50


is then supported by the tip


52


, where such support is enhanced by the tubular element


48


contacting or engaging cigarette periphery. This aspect also permits the manufacture of a cigarette which does not have all the usual characteristics of a conventional cigarette, such as, firmness, strength, end fallout and the like. The same may apply to the device of

FIG. 2

because the cigarette is housed in the tubular element and is thereby protected and not subject to constant tapping to remove ash as would be the case if the cigarette were smoked apart from the device. It is also understood that the tubular element of

FIG. 2

may have internal ribs to support the cigarette concentrically in the tube. The device of this invention allows for the use of a cigarette which may be made in a somewhat non-conventional manner. A number of the standard production processes may be avoided, such as, use of expanded tobacco, shredded or enhanced stem and the like which were required to provide desired cigarette firmness and appearance. Furthermore, the thin cigarette may be made with less tobacco in total and thereby requires considerably less quality tobacco.




As shown in

FIG. 5

, the tubular element


48


has an internal diameter defined by interior surface


68


which is essentially the same as the external diameter of the periphery


70


of the cigarette


50


. The tubular element


48


is then slid over the cigarette


50


where the periphery of the cigarette is in essence in contact with the interior surface of the tubular element


48


. The tubular element


48


, in being made of non-combustible material retains its structural integrity as the cigarette is smoked and recedes within the tubular element. The tubular element


48


simultaneously minimizes sidestream smoke from the burning cigarette as well as controlling the free-burn rate of the cigarette. Such retention of the sidestream smoke in the tube is achieved by the porous material absorbing and capturing the smoked particles and aerosols of the sidestream smoke. In addition, if catalytic particles are embedded in the porous tubular material, the odour causing constituents of the aerosols may be oxidized into odourless constituent or pleasant smelling constituents.




The porous material is of a structure in the form of a mat or sheet or the like which is capable of capturing such particles and aerosol and retaining them so that they are not released during the smoking of a new cigarette in the device in the event that the device is re-used. Furthermore, the porosity of the porous material is selected to control air flow and retain hot combustion gases in the region of the burning cigarette ember to achieve the desired reduction in free-burn rate so that smoking of the cigarette simulates the number of puffs associated with smoking of a conventional cigarette.




The tubular element


48


may be formed from a single sheet or mat. Alternatively, the tubular element


48


may be formed by layering several sheets or thin mats of the porous material to form the desired thickness for the tubular element. The tubular element may include an outer coating or wrapper such that the exterior of the tubular element resembles in colour, a cigarette or cigar. It is appreciated that such coating or wrapping must be porous to the extent that it does not appreciably interfere with the control that the porosity of the tubular element


48


provides in achieving the desired free burn rate and sidestream smoke control. Other types of exterior coverings are described with respect to

FIGS. 12 and 13

.




The tubular element


12


of the embodiment of

FIG. 6

has openings for controlling free-burn rate and sidestream smoke reduction. By selecting an appropriate opening size, such as width of slit


16


and providing a suitably sized annulus


44


, acceptable degree of sidestream smoke control and free-burn rate control can be achieved. The degree of sidestream smoke reduction is not as complete as compared to the device with component


18


in the slits


16


. The size of the slit is smaller than slit


16


of

FIG. 1

for controlling the rate of air flow into the annulus


44


. It is appreciated that the openings provided in the tube may also be pores which are preferably circular. The openings are precisely formed in the tube to provide the necessary reduced size of opening to achieve free-burn rate control. The openings may be formed in the tube by laser drilling or the like where it is understood that the opening size may permit some sidestream smoke to pass, but the openings will still provide a very substantial reduction in released sidestream smoke.

FIG. 6

also demonstrates the permanent attachment of the tip


20


to the tubular device


12


. The tip


20


may include an annular filter-like component


72


which has a bore


74


therein to receive the filter portion


76


of the cigarette


78


. The annular component


72


is then secured to the tubular member


12


by a suitable tip wrapping


80


which thereby gives the appearance of a finished cigarette and permanently connects the tip


20


to the tubular member


12


.





FIG. 7

shows an exploded view of the device of

FIG. 1

where the tip


20


can be removed from the tubular member


12


to expose the cigarette


14


and allow withdrawal of its filter portion from the tip


20


. A new cigarette has its filter portion


24


or just its tobacco rod portion then inserted in the tip


20


and the unit then reassembled by slipping the tubular member


12


over the land portion


32


.





FIG. 8

shows an alternative arrangement for the device


10


where attached to the tubular member


12


is a mouthpiece


82


. The mouthpiece


82


may receive in the body portion


84


, the tip of the tobacco charge and as well present a land portion onto which the tubular member


12


is slid. The tip


82


has the conventional narrowed portion


86


to feel comfortable in the smoker's mouth.




The tip


20


may resemble a normal cellulose acetate type cigarette filter having a filter plug


72


as shown in FIG.


9


. The land portion


34


may have its annular end


86


inserted in tube


12


to prevent drawing into the tip


20


, air from the annulus defined between cigarette


14


periphery and interior


40


of tube


12


. It is also understood that it may be desirable to draw a controlled amount of air into the tip


20


which can be achieved with conventional ventilation holes or ventilation techniques used in the filter tip


20


. The tip


20


has a recess or bore


73


in shoulder


34


as defined by end


86


. The tobacco rod end


75


is inserted in the bore


73


to secure the tobacco rod


22


in the spiral tip


20


to form a cigarette component. The tube


12


is then assembled on land


34


to complete the smoke device


10


. The device may be correspondingly disassembled to allow insertion of a new rod


22


for smoking.




Further enhancements to the structure include providing at the open end


85


of the tubular member


12


, a ring


88


, as shown in

FIGS. 10 and 11

. The ring may have an opening


90


which is approximately the same size as a diameter of the cigarette distal end


26


. The ring


88


, in accordance with one embodiment of the invention, is useful in retaining ashes in the tube


12


as the cigarette is smoked. The cigarette end


87


may be located slightly inwardly of the ring


88


to facilitate lighting of the cigarette in the assembled device.




Other variations in respect of the free-burn rate control device in combination with an outer casing are shown in

FIGS. 12 and 13

. In

FIG. 12

, the tubular member


12


has an outer casing


92


. The casing


92


has a plurality of openings


94


provided therein. These openings are in sufficient number and size to permit free flow of air therethrough to supply a quantity of air usually in excess of what is required for the burning cigarette. In order to control this flow of air and achieve the simultaneous sidestream smoke minimization and free-burn rate control, a thin tubular layer


96


of porous material is provided. The layer may be located on the interior surface of the porous tube


92


and optionally secured thereto. The layer


96


of porous material has a porosity which achieves the desired air flow control and hot combustion gas retention. In addition, the porous material is capable of absorbing and capturing the smoke. As with the other embodiments, when the device


10


is designed for re-use, the porous material


96


retains the captured smoke and does not release it upon lighting and smoking a fresh cigarette. Alternatively, the porous material


96


may be in the form of a replaceable tube which is inserted in the tubular element


12


.




With the embodiment of

FIG. 13

, a considerably thicker inner layer


98


of porous material is provided. The thickness of that layer may correspond with the thickness of the tubular member


48


of FIG.


5


. The outer casing


100


may be a very porous outer coating of high porosity paper, ceramic fibre, high temperature plastic and the like. As demonstrated, the outer wrapping


100


has a porosity as indicated by the openings


102


which are in sufficient number and size so as to not interfere with the functioning of the tubular porous member


98


. The inner tubular member


98


contacts the outer periphery of the cigarette


14


in the same manner as that described with respect to the embodiment of FIG.


5


. This is in contrast to the embodiment of

FIG. 12

, where the porous tubular member


96


is spaced from the periphery of the cigarette


14


to define an annulus


104


which is similar to the embodiment described in respect of FIG.


2


. The function of the tubular member


98


is the same as described with respect to the embodiment of FIG.


2


. The burning coal with ash portion advances inwardly of the tube. The porous material


98


controls air flow and also contains the preferred major portion of hot oxygen deprived combustion gases in the region of the burning coal to achieve the desired free-burn rate control.




With the embodiment of

FIGS. 12

,


13


and


15


, the cigarette


14


has its filter tip


24


extending through the tip


20


. The tip


20


may have a filter tip


24


receiving portion


95


which is optionally porous since it does not need to perform a filtering function. The receiving portion


95


is secured to the tube


12


by tipping paper


97


.




As shown in

FIG. 14

, a further alternative embodiment for the tubular member


12


is provided. The tubular member


12


is made from a spiral wrap


106


of non-combustible material. Intermediate material is provided on the interior


108


of the spiral wrap to fill the spiral spacing


110


with a component for controlling free-burn rate. In one embodiment, as shown in

FIG. 15

, the spiral wrap


106


may have secured on the inside thereof, a tubular member


112


of porous material. The tubular member


112


may function in the same manner as the devices described with respect to

FIGS. 12 and 13

, where an annular gap


114


is provided between the tubular member


112


and the periphery of cigarette


14


. Alternatively, as shown in

FIG. 16

, the wrap


106


may have secured to the interior surface


108


thereof a wrap


116


of porous material and which functions in the same manner as the porous material for tubular member


112


. The wrap


106


may be formed of any suitable non-combustible material, preferably ceramic fibre. The tubular member


108


or inner wrap


116


is also of a non-combustible material which is porous and is preferably made of activated carbon fibre.




The embodiment of

FIG. 17

may have a tubular element


12


of any of the above identified constructions and on the surface thereof, a temperature indicator


118


may be provided. The temperature indicator may consist of individual cells


120


which change colour, depending upon their temperature. As the burning coal of the cigarette burns inward of the tubular element


12


, the temperature in that region changes the colour of the individual cells


120


hence the smoker can visually track the movement of the coal inward of the element


12


and cease smoking of the device


10


when the last cell


120


A indicates that the burning coal is almost at the filter. The temperature indicator greatly facilitates the use of the device


10


and avoids the smoker puffing on a cigarette that has extinguished in the tubular element


12


by virtue of having encountered its filter portion. It is also understood that on a single use device, the tubular element


12


may be wrapped in porous cigarette paper. As the coal of the cigarette burns inward of the tubular element


12


, the cigarette paper will turn slightly off colour, thereby indicating the position of the burning coal within the tubular element


12


. Alternatively, the tubular element


12


may be of a non-combustible material which changes colour as the burning coal moves inward. It is understood that the adhesive used in completing the seam for the covering of the device


10


may be of heat sensitive material. That material then changes colour as the burning coal moves inward of the tubular element


12


. The wrapping may be formed of a non-combustible heat resistant material such as ceramic fibre so that the device may be re-used. The material for gluing the same, may be of a composition which is capable of repeatedly changing colour as the burning coal moves inwardly of the tubular element


12


.




In order to achieve a unique interfit of cigarette tip with holder, a mating cigarette tip configuration and holder interior may be provided, as shown in

FIG. 18. A

cigarette


14


has its tip portion


24


formed with a longitudinally extending recess


122


. The holder tip portion


20


has a detent


124


extending longitudinally inwardly of bore


30


. The shape of the recess


122


is such to form a mating fit with detent


124


, and thereby ensure that only cigarettes designed for use with this holder


20


may be used in the device. Such design may be relied on to ensure, for example, that correct length of cigarette is used with the correct filter size in tip


20


or that the correct cigarette brand is used in the device.




Another alternative embodiment for the tubular member


12


is shown in

FIG. 19

where a tortuous path for the flow of air into the tubular member and for the sidestream smoke toward the exterior of the tubular member is shown. A cigarette


14


is surrounded by three concentric tubes. The first two inner tubes


130


and


132


have longitudinal slits defined therein similar to that of the tubular member


12


which is the outer tube. The inner tube


130


has its slits


134


offset from the slits


136


of the adjacent tubular member


132


. An annular space


138


is provided between the cigarette periphery in the interior of tubular member


130


. A thin space


140


is provided between tubular members


130


and


132


and as well a thin space


142


is provided between tubular member


132


and tubular member


12


. Such narrow spacing between the tubular members provides a controlled degree of communication between the openings in the respective tubes in forming the tortuous flow paths. Tubular member


12


has positioned therein the usual matting, woven fibre or stranded fibre to provide for the free-burn rate control and sidestream smoke control. The sidestream smoke as it emanates from the burning cigarette


14


travels outwardly through slits


134


and then follows a tortuous path between tubular members


130


and


132


to travel out through the apertures


136


which are out of register with the apertures


134


and then back through the space between tubular members


132


and


12


to encounter the porous material


18


in the outer slit


16


of the tubular member


12


. By providing this tortuous path of flow for the sidestream smoke, an enhanced filtration effect takes place along with further cooling so that the exterior of the tubular member


12


is comfortable to the touch and at the same time reduces order at the periphery of the cigarette.




An alternative embodiment for the tubular member


12


openings is shown in

FIGS. 20 and 21

. The tubular member


12


has the apertures


143


formed therein in a special manner to enhance sidestream smoke control while still providing the necessary free-burn rate control. This is accomplished, as shown in the section of

FIG. 21

, where the apertures


143


are fabricated in the tubular wall by, for example, punching or piercing the tubular member


12


to provide burrs or protrusions


144


of fibrous material which project inwardly of the inside diameter


146


of the tubular device


12


. The tubular member


12


is normally of a fibrous type of material so that the burrs


144


project fibres


145


inwardly of the tube to further enhance filtration and treatment of sidestream smoke which attempts to flow outwardly through the apertures


143


.




As shown in

FIG. 21

, the burrs


144


perform a locating feature in positioning the cigarette


14


centrally within the tubular member


12


to define gap


44


. Such positioning of the cigarette within the tubular member by the burrs


144


further enhances the sidestream smoke treating feature of the burrs in that smoke needs to flow through the fibres


145


of the burrs before any vaporous products can be emitted through the apertures


143


. It has been surprisingly found that by the use of this type of aperture formation in the tubular member


12


, not only is the smoking sensation of the element very close to that or the same as smoking a normal cigarette, also, the smell around the periphery of the cigarette is normal and does not emit an off smell.





FIG. 22

shows yet another alternative embodiment for the tubular member


12


where the tubular member may be thinner or approximately the same thickness as the other tubular members of FIG.


20


. The thickness is indicated by the end


148


of the tubular member. The tubular member


12


is spaced from the cigarette


14


by the annular gap


150


. The thin tubular member is made up of overlapping sheets of ceramic fibrous material which has been conditioned or mildly calcined in an oven to remove by combustion most of the binder material from the ceramic fibres. The sheet then becomes porous because by combustion removal of the binder from the sheet, a mass of intercommunicating voids are provided to form the porous sheet. The very porous sheet can be formed into a tube by wrapping the sheet several times upon itself. The end result is a tubular member of very small pores which may allow escape of non-visible volatiles but at the same time performs the necessary sidestream smoke control and free-burn rate control for the burning cigarette


14


. By selection of a suitable ratio for ceramic fibres to combustible binders used in making the base sheet, the heating of this material can produce the desired porosity by the controlled calcining of the formed tube which removes a desired amount of the organic binders such as cellulose. The sheet is wrapped upon itself to form the tubular member


12


which is then calcined to form matrices of communicating pores in the tubular member in providing the required porosity and pore sizing to control sidestream smoke and free-burn rate.





FIG. 22

also shows a special arrangement for the cigarette


14


in the tube


12


. The end


26


of the cigarette may be spaced inwardly of the end


148


of the tube. It has been found that the cigarette


14


can be lit by drawing the hot gases of the flame


151


of the lighter


153


into the tube where the cigarette end


26


is positioned well within the tube


12


. For example, the end


26


may be located up to one-half the cigarette length away from the tube end


148


. The recessed positioning of the cigarette end reduces the amount of sidestream smoke which could be released on lighting the cigarette in the device


10


.




Various structures have been described for the filter tip portion or mouthpiece portion of the device


10


. An alternative construction for the filter tip is shown in

FIGS. 23 and 24

where the filter tip


20


comprises a sleeve


160


which may be cylindrical to provide a cylindrical shoulder


162


. The cylindrical tubular element


12


is friction fitted on the sleeve shoulder


162


by virtue of its interior surface


164


being approximately the same diameter as the shoulder


162


. The sleeve has an annular flange


166


which defines a stop against which the end


168


of the tube abuts. Filter tipping paper


170


surrounds a thin insert


172


which withstands crushing in this area of the filter to ensure that space


190


is maintained. The tipping paper


170


and sleeve


172


may be adhered to the tubular element to complete assembly of the filter tip on the tube. Alternatively, the tubular element may be separated from the filter to facilitate insertion of a new cigarette. When it is desired to provide a degree of ventilation in the cigarette mainstream, ventilation holes may be provided in the insert


172


in the normal manner.




The sleeve


160


has a bore


174


formed therein which snugly receives on a friction fit basis, an end portion


176


of the tobacco charge


22


. The friction fitting of the tubular tobacco charge in the sleeve


160


supports the tobacco charge and locates it within the tubular element


12


. The sleeve


160


may have integrally formed therewith or connected thereto, a tubular porous support structure


178


which may be wire mesh. The porous tubular structure


178


supports micro-fibre material


180


. The micro-fibre material may be made in accordance with the process described in applicant's Canadian patent 1,057,924; U.S. Pat. No. 3,882,877 and published international application WO 90/09741. These references describe the use of such micro-fibre material in cigarette filters. The micro-fibre material is very efficient in filtering tobacco smoke while at the same time providing a very low pressure drop as the smoke flows through the filter. The smoke enters the tubular filter


20


through the central opening


182


in the direction of arrow


184


. The smoke travels radially through the first tubular filter


180


, as indicated by arrows


186


. It is appreciated that as the filter removes particulates from the cigarette smoke, the smoke travels further down the tubular filter


186


so that the efficiency of the filtration material is not compromised. Optionally surrounding the micro-fibre material


180


is a second tubular filter


188


which is of a second filtration material. Preferably, the second tube


188


is concentric with and overlaps the first tubular filter


180


. Preferably, the second tubular filter is made of carbon and especially activated carbon to remove particulates from the smoke stream as well as modify the flavour of the cigarette smoke. The second tubular filter


188


is placed in the annular space defined between the first filter


180


and the plastic insert


172


. With the second tubular filter in place, an annular space


190


is defined between the second filter and the tipping paper. The smoke flows in the continued direction of arrow


186


along the annulus


190


and around a stop


192


which has an annular array of apertures


194


which allow the smoke to flow into a plenum


196


. The plenum distributes the smoke across the interior face


198


of the filter plug


200


to distribute the smoke to flow in a direction of arrows


202


through the filter plug


200


. The stop


192


in this embodiment closes off the end portion


204


of the first filter tube


180


to ensure that the smoke is forced to flow through the micro-fibre filter material when someone drags on the cigarette device. This construction for the filter tip is particularly beneficial in directing the mainstream flow of smoke from the thin cigarette


14


through multiple component filter arrangement to ensure proper filtration and provide a mainstream smoke at the filter tip which is pleasing to the smoker and provides the normal expected flavour, tasted and pressure drop.




With reference to

FIG. 25

, a preferred embodiment in the construction of the filter tip of

FIG. 23

is shown. In

FIG. 25

the device for supporting the first tubular filter material which may of micro-fibre material is an injection molded element


206


. The element has the sleeve


160


with the defined outer shoulder


162


, the stop


166


and the inner bore


174


. The support


178


for the first filter material has a plurality of slots


208


extending along its length to allow cigarette smoke passing through the opening


182


in the tubular support to pass radially through the slots


208


. As noted, the stop


192


includes a planar portion


210


which blocks off the end region of the tubular support


178


for the first filter material. In addition, the stop


192


includes buttons


214


which provide a spacer for locating the filter plug


200


of

FIG. 24

from the inner face


216


of the stop to provide the plenum


196


, as described with respect to FIG.


24


. As shown in

FIG. 25

, the buttons


214


are located about the periphery of the stop


192


. In addition, the aperture


194


space between button supports


212


are shown through which the tobacco smoke flows in filling up the plenum


196


.




As previously noted, the tobacco charge may take on the form of a tobacco rod formed in a highly porous mesh and sold under the trade-mark “Custom Cut” by Rothmans, Benson & Hedges Inc. Such tobacco rod, if smoked on its own, would be too porous to permit smoking. It is understood that the tubular member


12


may be adapted to reduce the porosity of the mesh holding the tobacco rod to render it smokeable. This may be accomplished by providing within the tubular member


12


, an inner sheath into which the tobacco rod is slid or to adapt the embodiment of

FIG. 5

or


13


to encase and contact the periphery of the tobacco rod to provide the necessary reduction in porosity so that the tobacco rod may be smoked. Other variations for a normally non-smokeable product include modifying the cigarette filter


24


of

FIG. 2

such that the filter wrapping paper or exterior is too porous to effect any draw on the lit tobacco charge. However, when the porous filter tip


24


of cigarette


14


is inserted in the tip


20


, the interior of the bore in the tip


20


of for example

FIG. 12

, seals off the porous filter exterior so that the cigarette becomes smokeable. Another alternative is to position a strong unfiltered wrapped tobacco rod which is too strong to smoke normally, in the tip


20


to provide the desired filtered smokeable flavour and taste.




The device surrounding the cigarette or cigar, provides a significant safety feature should the device be accidentally set down on an ignitable material. The non-combustible tubular member contains the burning coal of the cigarette and prevents direct contact of the burning coal with the potentially ignitable material. This arrangement then greatly reduces the chances of accidental fires caused by a burning cigarette. In addition, the tubular element, either by virtue of the annulus or its thickness, provides a perimeter which although hot to the touch, is not at a temperature which would burn a smoker. Although the tubular element may become warm during the smoking process, it would not be so hot as to burn the user. The tubular element ends preferably with the end of the tobacco rod and may even be flush therewith. Because the tubular element is non-combustible, a flame may be applied to the end of the device to ignite the distal end of the cigar or cigarette so that smoking may commence.




As previously noted, a further benefit in providing the various embodiments of this invention is to include catalytic material or particles which function to convert odour causing gases into substituents which have less or no odour. Depending upon the efficiency of the sidestream smoke control aspect of the device, it has been observed that the only constituents escaping through the tubular element are invisible odourless gases. It is therefore important to reduce this smell either by allowing some of the smoke constituents to emanate as invisible vapours to mask the smell or to take steps to reduce the smell so that it is not noticeable during the smoking process. As is understood, considerable amounts of odour causing gases are emitted from a burning cigarette during the normal smoking process, however, strong smells from such odour causing gases are masked by all of the other constituents of smoke which are emitted with the sidestream smoke. It has been found however that suitable catalysts which may be of the precious metals, rare earth metals and the like, and mixtures thereof either as catalysts or metals in the catalyst. Preferred metals include platinum or cerium which may be used to oxidize the odour causing gases to render them odourless. The catalyst particles may be included in various aspects of the tubular member. They may be placed in the porous material, put in the various types of openings in the tubular member and, for example, when making the matted material


18


, the catalytic particles may be included in the matting. Catalytic materials may be applied to the interior or exterior of the tubular member or may be adhered to the fibrous strands which are placed in the slits of the tubular member. It is also appreciated that the catalytic material may be applied as a thin film to the interior of the tubular member or in the apertures


104


of the embodiment of

FIGS. 12 and 13

. The catalytic material may be included as a heat treated material in the apertures


104


to provide further sidestream and free-burn rate control as long as the catalyst is positioned in an area where it achieves the desired oxidation of the vaporous materials in the aerosols which permeate the tubular member.




The catalytic material as included in the material for making the tubular member such as with the manufacture of the matt


18


, has provided significant benefits in converting odour causing invisible gases to either odourless gases or gases with an acceptable odour and at the same time, allowing one to exercise additional control in providing the required predetermined porosity in the tubular element. The advantages are particularly apparent when the catalyst is used in the manufacture of the calcined tubular members of FIG.


22


. The tubular member may be formed by wrapping two or more layers of the formed ceramic precursor sheet to provide a tubular shaped member. The sheet may be formed in the usual manner by making a slurry of the ceramic precursor material which includes clays, alumina sol binders, various types of organic binders, aluminum oxide and other normal constituents usually included in a ceramic precursor. In order to prepare the sheet, this slurry with high solids content is laid out in accordance with usual papermaking processes, rolled and dried to form a sheet of ceramic precursor material. The sheet is then, as previously noted, wrapped upon itself one or more times depending upon the thickness of the sheet to provide a tubular member of a desired thickness. In the manufacture of the sheet, catalytic materials and/or catalytic precursor materials may be incorporated in the slurry and either solubilized or dispersed in the slurry whereby the catalytic material, either in the form of a catalyst or precursor is correspondingly in the sheet material when wrapped into the tubular element and during the mild calcining of the tubular element. It has been found that the presence of the catalytic material provides an additional controlling factor m achieving a desired porosity in the tubular member and as well, by virtue of its in situ presence in the tubular member, provides enhanced oxidation of the odour causing gases as they pass through the tubular element. Such enhanced oxidation is compared to coating the tubular element on the inside with a catalytic material.




Although it is believed that a variety of catalytic materials may be used such as the previously mentioned catalytic materials based on precious metals, rare earth metals and the like, which include platinum or cerium, it has been found that the preferred precursor catalytic material for incorporation in tube manufacture, is a cerium oxide catalyst precursor, namely, hydrated cerium oxide. This material may be obtained from Advanced Material Resources of Toronto, Ontario, Canada. The inclusion of the hydrated form of cerium oxide in the ceramic precursor slurry results in its crystalline structure changing during the mild calcining process. The cerium oxide is dehydrated to become an alternative crystalline cerium oxide in the calcined material, normally in the form of crystallites. During the conversion of the hydrated cerium oxide to cerium oxide catalyst it is thought that the developing cerium oxide catalyzes the oxidation, i.e., burning of the binder material, particularly when the binder is organic such as cellulosic material. It is though that the catalyzed oxidation of the binder material enhances the size of the pores being formed in the tubular element as it is calcined. By virtue of the presence of the catalytic cerium oxide, the extent of oxidizing of the cellulosic material can be controlled to provide a desired pore size in the material to achieve the desired predetermined porosity in the tubular element.




Another advantage to the in situ incorporation of the cerium oxide catalyst in the tubular element is that an enhanced oxidation of invisible odour causing volatiles is achieved to thereby reduce any unpleasant odours emanating from the cigarette construction. It has been found that the invisible volatile components include ammonia and aldehydes. The in situ presence of the cerium oxide has surprisingly, even in the presence of high levels of carbon monoxide competing for oxidation sites on the catalyst, achieved oxidation of the ammonia and aldehyde constituents converting them into odourless constituents or at least constituents which have a more normal odour associated with cigarette smoking. It is particularly surprising in view of all of the chemicals of combustion from a burning cigarette, that the cerium oxide catalyst works particularly well in neutralizing the smell of ammonia in the invisible volatiles which permeate the porous tubular member.




Although the in situ formation of the cerium oxide catalyst in the tubular element is advantageous in not only catalyzing oxidation of the volatiles but as well providing an enhanced control on the porosity of the element, it is appreciated that the cerium oxide catalyst may be applied in sintered form as a powder to the interior of or exterior of the tubular element or within the openings of the tubular element or on the matting for openings in the tubular element, as previously described with respect to the other type of catalyst.




Various aspects of the several embodiments are exemplified as follows where such specific examples are not intended to be limiting the scope of the claims.




The cigarette for the device may range in size from about 3.5 mm to 10 mm and preferably about 4 to 8 mm in diameter. Very acceptable performance has been realized with cigarettes having diameters of about 4 to 5 mm. In order to provide the desired flavour and taste in the mainstream smoke, particularly with the thinner cigarettes, it is understood that the blend of the cigarette may be modified in accordance with the blending processes described in applicant's U.S. Pat. No. 5,524,647. The packing density of the cigarette, even with the thinner cigarettes does not having to be special. Normal packing densities may employed such as in the range of 200 to 300 mg/cm


3


. The device provides the desired number of puffs for the thinner cigarette so that there is no need to use higher or lower than normal packing densities. The cigarette may be wrapped in any suitable cigarette paper of a porosity which may be greater than porosity of the tube. The paper porosity should range from 10 to 100 Coresta units and preferably 40 to 60 Coresta units. Vanillin and other flavour additives may be incorporated in the paper. The free-burn rate of the thin cigarettes in normal smoking conditions, i.e., outside of the tube, is quite high. For example, with a 5 mm diameter cigarette with normal blend, packing density and cigarette paper, the free-burn rate is about 5 mm/minute. With the 4 mm diameter cigarette, the free-burn rate is significantly greater, namely, 8 to 10 mm/minute. This is very high considering a normal 8 mm cigarette has a free-burn rate of about 3 mM/minute. Considering that use of the device converts a thin cigarette of normal length into an 8 to 10 puff cigarette is quite surprising while maintaining desired taste and flavour for the smoker.




The physical parameters of the tube which provide these features include a porosity value for the tube in the range of about 20 Coresta units up to about 60 Coresta units. When the device is assembled, the pressure drop for the unit may range from about 0.5 cm H


2


O column to 25 cm H


2


O column and preferably 3 to 14 cm H


2


O column and most preferably 5 to 10 cm H


2


O column. The interior diameter of the tube is about 7 to 10 mm with a tube wall thickness of about 0.25 mm to about 0.5 mm. The preferred cigarette diameters are about 4 or 5 mm to provide a gap spacing of about 0.5 mm to 3 mm, preferably about 1 to 2.5 mm and most preferably about 1.5 to 2.5 mm. During use with this range of gap spacing between cigarette and tube, the cigarette attains a temperature of about 600 to 800° C. during puff and about 400 to 600° C. during idle. The tube is at a considerably lower temperature in the range of about 120° to 200° C. The tube external temperature is preferably wrapped in normal cigarette paper having a porosity of 10 to 100 Coresta units and preferably 40 to 80 Coresta units where the porosity of the paper should be greater than that of the tube to ensure the paper does not interfere with tube porosity factor controlling free-burn rate. It has been found that if a catalytic material, such as, cerium oxide is applied to the outside of the tube, the combustion of the paper is catalyzed so that there is greater paper discoloration at each puff to indicate clearly the location of the burning coal in the tube. With this range of porosities for the tube and paper where the porosity is somewhat uniform across the material, no visible sidestream smoke passes through the tube only invisible volatiles pass which can be treated in the presence of catalyst to convert the gases to odourless constituents.




The preferred cigarette filter construction of

FIG. 24

, has a very low pressure drop, usually one-half the pressure drop of a normal filter, namely in the range of about 1 to 3.




The preferred catalytic material is a mildly calcined hydrated form of cerium oxide (Ce


2


O


3


×H


2


O) which is available from the aforementioned AMR of Toronto. The catalyst may be incorporated into the sheet manufacture where a slurry composition of about 90 to 95% by weight water includes inorganic materials of glass fibres and micro-fibres, clay, talcs and the like and organic binders of acrylnitriles and acrylic based latex. In addition, to hold paper strength before calcining, the slurry may include cellulosic fibre. In the finished dried paper, the inorganics may comprises up to 90% by weight of the paper. The paper normally has a thickness of 5 to 10 mil and is wrapped upon itself 2 to 3 times in making the tube. The tube is mildly calcined by heat treating in an oxidizing atmosphere at a first phase temperature of about 220 to 260° C. and a second phase temperature of 400° C. to 600° C. This stagewise heating ensures a release of the volatiles without puffing the material. The catalyst may be incorporated on a dry sheet weight basis of about 0.5 to 10%. Preferably the catalyst precursor is incorporated at about 1 to 5% by weight and most preferably 1 to 3% by weight. With suitable organic loadings a desired porosity in the tube is achieved when the pore size is capable of restricting flow to control free-burn rate and contain the hot combustion gases in the tube. Preferred densities of the paper have a density of about 0.70 gm/cm


3


to 0.80 gm/cm


3


which is achieved with a higher organic loading in the slurry.




In a preferred embodiment of the invention the tubular element may have an exterior dimension the same as that of a conventional cigarette so that the overall appearance of the device with the tip in place is that of a conventional cigarette. By virtue of free-burn rate control, the thin non-conventional cigarette used within the device may have considerably less tobacco perhaps up to three quarters less tobacco, and in accordance with a preferred embodiment of the invention may have two-thirds less tobacco. The free-burn rate control ensures that the cigarette, during its idle period, burns sufficiently slow that the usual number of puffs are obtained from the device of this invention corresponding to that obtained from a conventional cigarette. The significant reduction in the amount of tobacco used which would normally be waste in a conventional size cigarette, now provides a significant cost saving in cigarette manufacture while still realizing all of the other advantages and features of a conventional cigarette.




Preferred embodiments of the invention have been described herein. It is understood that variations may be made thereto without departing from the spirit of the invention or the scope of the appended claims.



Claims
  • 1. A device for minimizing cigarette sidestream smoke and reducing free-bum rate of a burning cigarette in combination with a filter tip,a) said device comprising: i) a non-combustible porous tubular element encasing an effective length of a tobacco charge of a cigarette located in said tubular element, said tubular element having an open end adjacent a distal end of said cigarette to permit lighting of the cigarette distal end and to permit ingress of air while said tobacco charge is burning; and ii) said tubular element having a predetermined porosity along at least its length which encases said effective length of said tobacco charge for both minimizing sidestream smoke emission from the tobacco charge when burning and reducing free-burn rate of the tobacco charge when burning to increase number of puffs from the tobacco charge when burning; and b) said filter tip comprising an inlet end and an outlet end, said inlet end having an annular sleeve with a central bore to receive an end of said cigarette, said annular sleeve having an outer shoulder onto which said tubular element is friction fitted, said central bore being in communication with a first inner tube of a first filter material, said first inner tube having a closed end opposite an end of said first inner tube in communication with said sleeve central bore, an annular space being provided outside of said first inner tube, a filter plug provided downstream of said annular space and filling said outlet end of said filter tip, a plenum between said filter plug and said first inner tube for transferring filtered smoke from said annular space to said filter plug.
  • 2. The device in combination with the filter tip of claim 1 wherein said effective length of said tobacco has a diameter in the range of about 4 to about 6 mm.
  • 3. The device in combination with the filter tip of claim 1 wherein a second tube of a second filter material is concentrically located in said annular space about said first tube.
  • 4. The device in combination with the filter tip of claim 3 wherein said filter materials of said first and second tubes is are selected from a group of materials consisting of cellulosic material, glass ceramic or carbon fibre matting material, activated charcoal material, micro-fibre material and any of said materials incorporating a catalytic material.
  • 5. The device in combination with the filter tips tin of claim 1 having an annulus between an interior surface of said tubular element and cigarette periphery, said annulus defining a gap spacing of about 0.5 mm to about 3 mm.
  • 6. The device in combination with the filter tip of claim 1 wherein the cigarette in said tubular element is inherently unsmokeable and becomes smokeable when inserted in said tubular element.
  • 7. The device in combination with the filter tip of claim 1 wherein the cigarette in said tubular element has a filter element which is sufficiently porous to render the cigarette inherently unsmokeable and becomes smokeable when inserted in a filter tip portion of said tubular element.
  • 8. The device in combination with the filter tip of claim 1 wherein said open end of said tubular element is open while said cigarette is smoked and said open end is adjacent a distal end of said cigarette.
  • 9. The device in combination with the filter tip of claim 1 wherein said predetermined porosity for said tubular element:a) retains around a burning ember of said cigarette oxygen deprived combustion gases within said tubular element to reduce rate of combustion and minimizes release of smoke particles through said porous tubular element; and b) restricts inward flow of air to reduce free-bum rate of said cigarette.
Priority Claims (1)
Number Date Country Kind
9621466 Oct 1996 GB
RELATED APPLICATIONS

This application is a divisional of U.S. Ser. No. 09/284,633 filed Apr. 15, 1999, now U.S. Pat. No. 6,371,127 which is 371 application of PCT/CA97/00762 filed Oct. 15, 1997 and published under PCT Article 21(2) in English.

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1583284 Oct 1969 FR
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Non-Patent Literature Citations (1)
Entry
PCT/CA97/00762 International Search Report dated Apr. 2, 1998.
Provisional Applications (1)
Number Date Country
60/037562 Feb 1997 US