Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02469457 2004-06-16
CIGARETTE SIDESTREAM SMOKE AND
FREE-BURN RATE CONTROL DEVICE
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 number 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 cigarette 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, firnmess 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.
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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
control 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. Patents 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
}
CA 02469457 2004-06-16
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the amount of sidestream smoke. Examples of such devices are shown in
U.S. Patents 1,211,071; 3,827,444 and 4,685,477.
Further, various types of cigarette holders have been made available
which serve 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. Patent 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. Patents 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. Patent 4,638,819 and International
application WO 96/22031. 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. Patent 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
CA 02469457 2004-06-16
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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. patents 5,592,955
issued January 14, 1997 and U.S. patent 5,105,838 issued April 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
According to an aspect of the invention, there is provided 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 for encasing an
effective length of a tobacco charge of a cigarette when located in said
tubular
element, said tubular element having an open end for positioning adjacent a
distal
CA 02469457 2004-06-16
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
when
5 the tobacco charge is positioned within said tubular element 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.
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
fbrm
fibrous projections within the tube where such projections may be relied on to
centre 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 combustion 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 precursor material which is rendered porous by the heat
treatment. The makeup of the ceramic precursor material and the heat
CA 02469457 2005-06-29
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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.
According to an aspect of the present invention, there is provided in a
method for treating cigarette smoke, the use of a catalyst to convert odour
causing ammonia and aldehydes in the cigarette smoke to odourless gases or
gases with acceptable odour, wherein the catalyst comprises cerium oxide or a
precursor of cerium oxide.
BRIEF DESCRIPTION OF THE DRAWINGS
Various aspects of the invention are shown in the drawings wherein:
Figure 1 is a perspective view of the preferred embodiment of this
invention showing the device in which a cigarette tobacco charge is encased;
Figure 2 is a section along the device of Figure 1;
Figure 3 is a section along the lines 3-3 of Figure 1;
Figure 4 is the enlarged view of an end view of the device;
Figure 5 is a perspective view of an alternative embodiment of this
invention showing the device encasing a tobacco charge of a cigarette;
Figure 6 is a section along an alternate device;
Figure 7 is an exploded view of the reusable device;
Figure 8 is a perspective view of the device with a mouthpiece or tip;
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6a
Figure 9 is an exploded view of an alternate device;
Figure 10 is a section of an end of the device;
Figure 11 is an exploded end view of the device of Figure 10;
Figure 12 is a longitudinal section of an alternative structure for the
device of Figure 1;
Figure 13 is a longitudinal section of an alternative embodiment for the
device of Figure 12;
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Figure 14 is a perspective view of an alternative spiral wrap
construction for the tubular member;
Figure 15 is a longitudinal section of the spiral construction of Figure
14;
Figure 16 is a longitudinal section of an alternative construction for the
spiral configuration of Figure 14;
Figure 17 is a plan view of the device with a temperature indicator;
Figure 18 is an exploded view of a cigarette tip adapted to fit a holder
with detent;
Figure 19 is a cross-section through an alternative embodiment for the
tubular element;
Figure 20 is a perspective view of an alternative embodiment for the
tubular element;
Figure 21 is a section of Figure 26;
Figure 22 is a longitudinal section view of an alternative embodiment
for the tubular element having a porous wrap of ceramic sheet;
Figure 23 is an exploded view of an alternative embodiment for the
filter tip;
Figure 24 is a section through the assembled device of Figure 23; and
Figure 25 is a perspective view of an injection molded component of
the device of Figure 23.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIM[ENTS
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 muiimizes 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
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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 2/3 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 2/3
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
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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 immediatety 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. patent 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 Figure 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 Figure 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
CA 02469457 2004-06-16
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
5 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 Figure 2, the tubular device 12 encases the cigarette 14
which has a wrapped tobacco rod portion 22 and in accordance with this
10 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
has a bore 30 provided therein to receive snugly the filter tip 24 of the
20 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 defme a land 34 over which the tubular element
12 is slid to provide the assembled unit of Figure 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 Figure 1.
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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 Figure 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
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 minimi~ing sidestream smoke
10 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 Figure 3, the slit 16 defines an
opening 46 having the component 18 provided therein to effect control of the
cigarette free-burn rate and minimi~e 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,
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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 Figure 4. The tubular element 12 has the longitudinally
extending slits 16 filled with a porous material 18 as in the earlier
described
embodiment of Figure 1. The difference however is the composition for the
fibrous material 18, as shown in more detail in Figure 4. Instead of a
matting, as described with respect to Figure 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
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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 Figure 2, the
burning cigarette has an ember or coa121 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
CA 02469457 2004-06-16
14
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 burrung 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 Figure 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
CA 02469457 2004-06-16
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
Figure 4.
5 It is appreciated that the openings formed in the tubular element of the
embodiment of Figure 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
10 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.
15 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 Figure 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 Figure 5
demonstrates an alternative arrangement for the tubular element 48 of the
CA 02469457 2004-06-16
16
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 embod'unent of Figure 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 materia154 extending the length of the
tubular element 48 to the filter tip line 56 of the tip 52. The porous
material,
as with the embod'unent.of Figure 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 Figure 1. The tip 52 has a reduced 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 Figure 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 Figure 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 Figure 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
CA 02469457 2004-06-16
17
enhanced stem and the like which were required to provide desired cigarette
fffmn.ess and appearance. Furthermore, the thin cigarette may be made with
less tobacco in total and thereby requires considerably less quality tobacco.
As shown in Figure 5, the tubular element 48 has an internal diameter
defmed 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
CA 02469457 2004-06-16
18
burn rate and sidestream smoke control. Other types of exterior coverings
are described with respect to Figures 12 and 13.
The tubular element 12 of the embodiment of Figure 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-
bum 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 Figure 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.
Figure 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 fmished
cigarette and permanently connects the tip 20 to the tubular member 12.
Figure 7 shows an exploded view of the device of Figure 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.
Figure 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
CA 02469457 2004-06-16
19
mouth.
The tip 20 may resemble a normal cellulose acetate type cigarette filter
having a fzlter plug 72 as shown in Figure 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
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
15 end 85 of the tubular member 12, a ring 88, as shown in Figures 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
20 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 Figures 12 and 13. In Figure
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
CA 02469457 2004-06-16
the device 10 is designed for re-use, the porous materia196 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.
5 With the embodiment of Figure 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 Figure 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
10 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 Figure 5. This is in contrast to the embodiment
15 of Figure 12, where the porous tubular member 96 is spaced from the
periphery of the cigarette 14 to defme an annulus 104 which is similar to the
embodiment described in respect of Figure 2. The function of the tubular
member 98 is the same as described with respect to the embodiment of Figure
2. The burning coal with ash portion advances inwardly of the tube. The
20 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-bum rate control.
With the embodiment of Figure 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 ftmction. The receiving portion 95 is secured to the tube
12 by tipping paper 97.
As shown in Figure 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-bum rate. In one embodiment, as
shown in Figure 15, the spiral wrap 106 may have secured on the inside
CA 02469457 2004-06-16
21
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
Figures 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
Figure 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 Figure 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 120A
indicates that the burning coal is almost at the fitter. The temperature
indicator greatly facilitates the use of the device 10 and avoids the smoker
puffmg 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
CA 02469457 2004-06-16
22
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 Figure 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
Figure 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 defmed 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
CA 02469457 2004-06-16
23
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 toucli 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 Figures 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 Figure 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 Figure 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.
Figure 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 Figure 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
CA 02469457 2004-06-16
24
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.
Figure 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 Figures 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
CA 02469457 2004-06-16
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
5 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
10 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
15 made in accordance with the process described in applicant's Canadian
patent
1,057,924; U.S. patent 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
20 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
25 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 defmed between the
CA 02469457 2004-06-16
26
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. T'his 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 Figure 25, a preferred embodiment in the
construction of the filter tip of Figure 23 is shown. In Figure 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 Figure 24 from the inner face 216 of the stop to provide the
plenum 196, as described with respect to Figure 24. As shown in Figure 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
CA 02469457 2004-06-16
27
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 Figure 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 Figure 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 Figure 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
CA 02469457 2004-06-16
28
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 wbacli may be of the precious
metals, rare earth metals and the like, and mixtures thereof either as_
catalysts
or metals in the cat*st. Preferred metals'include platinunn 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 Figures 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 Figure 22. The tubular member may be formed
CA 02469457 2004-06-16
29
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
in 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
CA 02469457 2004-06-16
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
5 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
10 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
15 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
20 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
25 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
30 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.
CA 02469457 2004-06-16
31
The cigarette for the device may range in size from about 3.5 mm to
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
5 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. patent 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
10 mg/cm3. 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-bum 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 H20 column to 25 cm H20 column
and preferably 3 to 14 cm H20 column and most preferably 5 to 10 cm H20
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.
CA 02469457 2004-06-16
32
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 Figure 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 (Ce203 x H20) 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
puffmg the material. The catalyst may be incorporated on a dry sheet weight
CA 02469457 2004-06-16
33
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/cm3 to 0.80 gm/cm3 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.
