HK1022816B - Device for minimizing cigarette sidestream smoke and reducing free-burn rate of a burning cigarette - Google Patents

Description

Device for reducing sidestream smoke and reducing free-burn rate of burning cigarette

Technical Field

The present invention relates generally to a device that can be used in conjunction with a cigarette or other smoking article to control sidestream smoke and increase the number of puffs a smoker takes for a given amount of tobacco. The device, for example, enwraps only a desired amount of tobacco into a much smaller diameter cigarette, increases the amount of mainstream smoke emitted by the lit tobacco and maintains the traditional mouth feel while significantly reducing sidestream smoke. Rather than producing sidestream smoke when a thicker cigarette is lit, as in a conventional cigarette with a larger amount of tobacco, the use of a thinner cigarette in conjunction with the device converts tobacco normally wasted on sidestream smoke into mainstream smoke.

Background

Briefly, the device comprises a tubular member with a predetermined aperture 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 reduce sidestream smoke and reduce the free-burn rate between each puff. Very thin cigarettes can be inserted into the device and smoked the same number of times as a regular cigarette, which saves tobacco and other smoke producing materials and significantly reduces sidestream smoke. The tube may include a catalytic material to treat sidestream smoke components.

The device will be described in detail below and may be used for a number of different purposes, for example, in addition to cigarettes, tobacco material which cannot be smoked alone may be inserted into the device and smoking may be achieved by controlling the holes and apertures of the tube. It is clear that all the traditional quality requirements in the manufacture of cigarettes, such as robustness and end soot fall-back, are no longer the focus of the present invention.

The device is dimensioned for use with conventional cigarettes, which has the advantage that insertion of a thin cigarette into the device achieves the same smoking performance as a conventional sized cigarette.

When smoking by conventional means, three types of cigarette smoke are found, namely mainstream smoke, exhaled smoke and sidestream smoke. Since sidestream smoke comprises the majority of the smoke emitted during a puff, it is desirable to reduce the amount of sidestream smoke emitted from a lit cigarette or cigar. Attempts have been made to control sidestream smoke by one or more of the following techniques:

1) altering the loading characteristics of tobacco components and tobacco rods or tobacco material in a cigarette or cigar;

2) changing the packaging of cigarettes or cigars;

3) changing the diameter of the cigarette and its tobacco components; and/or

4) A device is provided on a cigarette or cigar to contain and/or control sidestream smoke emissions.

In order to reduce sidestream smoke and/or extinguish a lit cigarette or cigar when it is left for a period of time, a number of cigarette tobacco and cigarette paper compositions have been proposed which in some way influence the free-burn rate of the cigarette or cigar. These solutions include judicious selection of tobacco ingredients in the tobacco material, density, and multi-layer arrangement of cigarette tobacco. Such a selection can significantly slow the free-burn rate of the cigarette and increase the number of puffs per unit length of the cigarette. The components of the various wraps, whether combined with the selection and/or structure of the tobacco, or independent of the tobacco manufacturing process, can also affect the free-burn rate of the cigarette. The components of the cigarette paper comprise that chemicals are used for slowing down the free burning rate, and different kinds of cigarette paper with the same or different characteristics are wound in multiple layers to cover the cigarette paper and reduce the air permeability. See, for example, canadian patent 1259008 and U.S. patents 4878507 and 4915117.

Various devices for holding cigarettes are provided, primarily for preventing accidental fires. They may or may not include various types of filters for filtration to reduce sidestream smoke levels. Examples of such devices are disclosed in us patent 1211071; 3827444, and 4685477.

Further provides various cigarette holders which are mainly used for reducing the finger dyeing of smokers. The device may be attached to a cigarette holder and/or mounted on a cigarette, see for example us 1862679. Other types of cigarettes wrapped in a wrapper perforated in some manner to ensure safety and/or control sidestream smoke are disclosed in canadian patent 835684 and U.S. patents 3220418 and 5271419.

Devices which can be mounted on and slid along a cigarette to control the rate of combustion and free-burn are disclosed in british patent 928089, us patent 4638819 and international application WO 96/22031. The british patent describes a cigarette combustion control device obtained by restricting the air flow to the lit cigarette embers (ember). By slowing the burning of the cigarette, it is recommended to add only half as much tobacco to the cigarette as is required for ordinary tobacco, thereby making a shorter cigarette. The air flow restriction means may be a matrix of holes with variable openings in the device or a crimped portion of the device with longitudinal openings along the cigarette portion. Us patent 4638819 discloses a ring that is placed over and slid along a cigarette during smoking to control the free-burn rate of the cigarette and reduce sidestream smoke. The ring is a solid material, preferably metal, but it causes severe staining, and because of the variable diameter of the cigarette, the desirability of reducing sidestream smoke and the time to extinguish the cigarette cannot be reliably controlled.

Another possible ring system is described in Applicant's published PCT application WO 96/22031. The device has an inner ring which surrounds and contacts the periphery of a conventional cigarette, where the inner ring is a porous material. The outer ring surrounds the inner ring to direct the gas flow along the length of the porous inner ring. The tortuous path in the porous material of the inner ring controls the rate of diffusion of air into the coal tar (coal) of the lit cigarette, thereby controlling the free-burn rate of the cigarette. The porous material enhances the control of sidestream smoke emitted by a lit cigarette. The device is selectively extendable to half the length of the cigarette, where air must flow along the porous inner ring to the burning coal tar.

Other systems for controlling sidestream smoke are described in published PCT application WO95/34226 and U.S. patent 5592955 issued on 1-14 of 1997 and U.S. patent 5105838 issued on 4-21 of 1992. These references describe various tubular structures in which tobacco is disposed to reduce sidestream emissions from cigarettes.

While the above approaches may have met with some degree of success in controlling sidestream smoke emissions, some of these devices still have problems in maintaining traditional mouth feel and flavor, ease of use, ease of manufacture, streamlined appearance, and significantly reducing the amount of tobacco used. Embodiments of the present invention provide a device that overcomes some of the above problems by controlling sidestream smoke and free-burn rate while maintaining mouth feel, flavor, and composition release, etc., comparable to conventional cigarettes. The device of the present invention allows for the same number of puffs as a regular cigarette to be obtained when smoking a relatively thin cigarette containing only the tobacco necessary to deliver the desired mouth feel.

For the purposes of describing the invention, the term "tobacco material" is used to refer to cigarettes, cigars, cigarillo (cigarillo), tobacco rods in porous webs, tobacco cores or wrapped tobacco and the like. It will be appreciated that where the term "cigarette" is used, this may be replaced by a cigar, cigarillo or the like.

Disclosure of Invention

In one aspect the present invention provides a device for reducing sidestream smoke and reducing the free-burn rate of a burning cigarette, said device comprising:

i) a non-combustible porous tube surrounding an effective length of tobacco material of a cigarette in said tube, said tube having an open end adjacent the end of said cigarette for lighting said end of said cigarette and allowing air to enter; and

ii) said tube carrying means for reducing sidestream smoke emitted from the burning tobacco material while reducing the free-burn rate of the burning tobacco material to increase the number of times the burning tobacco material can be smoked, the means for reducing sidestream smoke and reducing free-burn rate comprising predetermined apertures of the tube distributed at least along the length of the tube containing an effective length of tobacco material, the predetermined apertures of the tube:

a) retaining at least a portion of the oxygen depleted combustion gas (oxygen depleted combustion gas) in the tube to reduce the release of smoke particles through the opening; and

b) the inward gas flow is restricted to reduce the free-burn rate of the cigarette.

The openings in the pipe member forming the predetermined porosity may take various shapes such as slits, grooves or holes, wherein the slits and/or grooves may be coated with a porous felt material of carbon fiber, glass fiber, ceramic fiber, high temperature plastic fiber, metal fiber, or the like. Fibrous projections may be formed in the tube, such as by punching, which center the cigarette in the tube, thereby forming holes in the tube wall. Alternatively, the tube may include a body portion of porous material which retains at least partially oxygen-free combustion gases within the tube and restricts inward gas flow to reduce the free-burn rate of the cigarette.

According to another alternative, the tube may be formed from a heat treated ceramic precursor material which is rendered porous by heat treatment. The ceramic precursor material is formed and heat treated in a manner to produce the desired predetermined porosity.

In the above device it can be seen that the cigarette is thin enough that the overall size of the device is the same as a conventional cigarette. The thin cigarette has a diameter of about 4-8mm, preferably about 4-6mm, and most preferably about 4 mm. In particular, when ceramic is used to form the tube, catalytic material may be added to the tube. The catalytic material may be coated on the tube or activated in the tube during heat treatment of the ceramic matrix. The catalyst may be chosen from those comprising noble and rare earth based metals, in particular based on platinum or cerium.

Drawings

The figures illustrate various aspects of the present invention:

figure 1 is a perspective view of a preferred embodiment of the present invention showing a device having a cigarette tobacco charge contained therein.

Fig. 2 is a cross-sectional view of the device of fig. 1.

Fig. 3 is a cross-sectional view taken along line 3-3 of fig. 1.

Fig. 4 is an enlarged end view of the device.

Figure 5 is a perspective view of another embodiment of the invention showing a device containing a cigarette tobacco charge.

Fig. 6 is a cross-sectional view of another device.

Fig. 7 is an exploded view of the reusable device.

Figure 8 is a perspective view of the device with a mouthpiece or filter plug.

Fig. 9 is an exploded view of another device.

Figure 10 is a cross-sectional view of one end of the device.

Fig. 11 is an exploded end view of the device of fig. 10.

Figure 12 is a longitudinal cross-sectional view of another configuration of the device of figure 1.

Fig. 13 is a longitudinal cross-sectional view of another embodiment of the device of fig. 12.

Fig. 14 is a perspective view of another spirally wound structure of a tube.

Fig. 15 is a longitudinal sectional view of the spiral structure of fig. 14.

Figure 16 is a longitudinal cross-sectional view of an alternative configuration of the spiral profile of figure 14.

Fig. 17 is a plan view of a device with a temperature indicator.

Figure 18 is an exploded view of a cigarette filter portion adapted for mounting a mouthpiece thereto by a key and lock.

Figure 19 is a cross-sectional view of another embodiment of a tube.

Figure 20 is a perspective view of another embodiment of a tube.

Fig. 21 is a cross-sectional view of fig. 26.

Figure 22 is a longitudinal section of another embodiment of a tube with porous ceramic sheet wrapper.

Fig. 23 is an exploded view of another embodiment of the filter plug portion.

Fig. 24 is a cross-sectional view of the mounted device of fig. 23.

Fig. 25 is a perspective view of an injection molded component of the device of fig. 23.

Detailed Description

The device of the present invention for reducing sidestream smoke emitted from tobacco material, such as in a cigarette, while controlling the free-burn rate has many features and advantages. In practice the device contains tobacco material and the device is less likely to catch fire, thereby providing a significant safety feature in the event that the ignited tobacco material accidentally lands on a combustible material. The device reduces sidestream smoke emitted from tobacco material, in part because the device also controls the free-burn rate. The device has the unexpected advantage that it can control sidestream smoke and free-burn rate while containing tobacco material therein, yet maintain all of the normal characteristics of a conventional cigarette smoking, such as appearance, feel, mouth feel and flavor. A catalytic material may be added to or coated on the device to promote further combustion of the various gases to avoid any off-taste when the cigarette is ignited in the device.

The device can be used with unconventional fine cigarettes, much finer than ordinary cigarettes, which can hold up to 2/3 tobacco to form tobacco material, thus providing a significant savings in the cost of tobacco and materials used in cigarette manufacturing. More specifically, very slim cigarettes with reduced unconventional smokeable times and apparently no more than 2/3 tobacco can be used. The device can be used with unconventional thin cigarette to achieve normal inhalation pressure, normal amount of inhaled smoke, normal flavor and taste, and normal smoking times. Without the device, smoking the unconventional thin cigarette does not achieve all of the above properties together.

An unexpected advantage of using a non-conventional thin cigarette in the device is that the smaller the diameter of the thin cigarette, the better the combustion can be maintained during shelf life to avoid deterioration of the taste. The device's function of controlling the free-burn rate ensures that the lit cigarette slows down the advancing rate of burning coal tar greatly during idle periods. Because of the small diameter of non-traditional slim cigarettes, the burning coal tar extends over the surface or cross-section of the small diameter cigarette. This is in contrast to the free-burn rate of a conventional sized cigarette when controlled. In conventional cigarettes, due to the excessive amount of tobacco in the larger cross-section, coal tar burns inwardly towards the central portion of the cigarette during periods of inactivity, and aerosol products agglomerate outside the cigarette. It is clear that the use of the prior art free-burn rate control device produces a particular result. In contrast, the effect of using the device according to the preferred embodiment of the invention in conjunction with a non-conventional fine cigarette is that, as the coal tar extends over the surface, it is ensured that it will burn well during periods of inactivity so that the combustion products do not condense on the outside of the fine cigarette. When the cigarette is picked up and smoked again, the step of inhaling causes the coal tar to immediately rise to a certain temperature and rapidly advance along the thin cigarette, so that no unpleasant taste is produced since the coal tar immediately rises to the normal smoking temperature. Another feature of the invention is that the unconventional slim cigarettes may be thinner than standard slim cigarettes having a diameter of about 5.5mm to 6 mm. The diameter of the non-traditional cigarette is less than 5.5mm, in particular less than 5.2mm, so that its structure is novel on the market. The thin cigarette, which is preferably used in the device, differs from a conventional cigarette in the number and size of puffs. The dimensions may be different not only in diameter but also in length. The slim cigarette is also provided with a suitable wrapper, preferably plain paper of conventional composition and porosity, as in conventional cigarettes. The wrapper may also include conventional burn rate modifiers such as those described in U.S. patent 4679575 to further slow the free-burn rate of the cigarette.

Another significant advantage of using a thin cigarette in the device is that the excess tobacco in a conventional size cigarette generates sidestream smoke. The device can minimize waste of tobacco during idle periods by controlling the free-burn rate. Conventional cigarettes waste tobacco on generating sidestream smoke during periods of inactivity becoming mainstream smoke on the next puff, thereby increasing the yield per unit of tobacco.

Some or all of the features of the present invention may be described in detail below with reference to one or more embodiments of the invention illustrated in the accompanying drawings. In fig. 1, the device 10 has a tube 12 for holding cigarettes 14. The device 12 extends over the effective length of tobacco material of a cigarette. The active portion of the tobacco material of the cigarette is intended to comprise the length of one cigarette which is normally smoked so that the smoker can smoke as many times as usual (typically 8-10 puffs) per conventional cigarette. The device 12 of this embodiment has a plurality of openings 16 around its circumference, one of which is shown in FIG. 1. The opening 16 is preferably a narrow slit extending longitudinally along the device 10. The opening of slot 16 feeds air into the burning cigarette to support the combustion reaction along the length of the opening, and an assembly 18 is provided to control the free-burn rate while minimizing sidestream smoke emitted from the burning cigarette in the same device. The tube 12 is connected to or integral with a mouthpiece portion 20, as in a conventional cigarette, to filter mainstream smoke drawn from a burning cigarette in the normal manner.

As shown in fig. 2, the cigarette 14 containing the wrapped tobacco rod 22 and the filter 24 in this embodiment are enclosed in the tube 12. The tube 12 preferably extends from the end 26 of the tobacco rod 22 to at least the filter line 28. The slot 16 extends at least to the rear of the effective length of the tobacco rod 22 to ensure that the cigarette will continue to burn until at least the number of puffs of a conventional cigarette are achieved. When the tobacco rod is drawn close to the filter line 28, the cigarette is extinguished, or the slit is made to terminate before the filter line 28, so that there is insufficient air to reach the burning end of the cigarette, so that the cigarette is extinguished before reaching the filter line 28. The filter portion 20 is provided with an internal bore 30 into which a cigarette filter 24 is suitably inserted to support the cigarette as it extends from the filter portion 20. It will be appreciated that cigarette 14 may comprise only a rolled tobacco rod 22 and no filter. At this point, one end of the tobacco rod may be inserted into and supported by the filter house 20. The inner bore 30 of the filter housing 20 forms a blind bore which does not extend through the filter housing 20. The constricted neck portion 32 of the filter portion 20 defines a circumferential groove 34 and the tube member 12 is slid through the groove 34 to form the assembled unit of figure 2. Tipping paper 35 is used for final wrapping to close the annular groove 34 to prevent air from entering the filter mouth portion 20 through the gap between the cigarette and the tube. The inner edge 36 of the tube 12 which contacts the engaging portion 38 of the mouthpiece portion 20 makes the assembled unit appear seamless, as shown in figure 1, like the appearance of a conventional cigarette.

The cigarette is supported by the filter mouth 20 such that the tobacco rod 22 is disposed substantially concentrically with the tube 12. As shown in figure 3, the inner diameter of the tube member 12 in this embodiment is defined by an inner surface 40, the inner surface 40 being spaced from an outer surface 42 of the circumference of the cigarette paper. This spacing forms an annular space or gap 44 extending along the length of the device 10 for connecting the tube member 12 to the filter head portion 20. The annulus 44 is controlled in combination with the element 18 in the opening 16 to minimize sidestream smoke and reduce the free-burn rate of the cigarette.

The tube 12 is made of a material that is impermeable to cigarette smoke. To maintain the structural integrity of the tube 12 during smoking, the material is non-combustible and withstands the temperature of the burning coal tar that recedes along the tube during smoking. Also, the component 18 in the opening 16 is non-combustible to ensure control of sidestream smoke and free-burn rate during smoking. Since the tube 12 is non-combustible, the device of the invention can be reused when a pack of cigarettes is drawn by simply removing the tube 12 from the mouthpiece portion 20 and withdrawing the cigarettes 14 from the mouthpiece portion 20. The device of the invention can be reused by inserting a new cigarette 14 into the mouthpiece portion 20 and reattaching the tube member 12 to the mouthpiece portion 20. It is of course also possible to provide each cigarette in a pack with the device 10 of the present invention, and simply discard the device after the cigarette has been removed.

As shown in the enlarged view of fig. 3, the slot 16 defines an opening 46 which contains the element 18 to control the free-burn rate of the cigarette and minimize sidestream smoke. Depending on the shape and size of the slots 16, a sufficient number of slots are provided along the tube 12 to arrange the assembly 18 so that sufficient air reaches the effective area of the tobacco rod to maintain the desired free-burn rate while allowing the same number of puffs as a conventional cigarette. The assembly 18 is preferably made of a non-combustible porous material. The porous material may be carbon fiber, preferably activated carbon fiber, ceramic fiber, glass fiber, high temperature plastic fiber, metal fiber, porous synthetic wood material (Photinia serrulata), etc. The fibers may be long fibers or felted or otherwise formed into a mat or sheet and the pores formed in the material by physical means (e.g., by laser drilling, by chemical extraction of soluble fine particles from the mat, or by removal of combustibles from the material by suitable calcination) to form a porous material.

The porous material, which may be a felt or a sheet, may be woven to provide a porosity that is dependent upon the number and size of the slots 16 selected to provide the necessary control over the desired free-burn rate of the cigarette. The location of the component 18 may be as shown in the slot 16, the component 18 may be a porous textile or a non-woven fabric, felt or a sheet of non-combustible material. This can be accomplished by dipping the tube 12 into a slurry of fibrous material used to form the mat. The fibrous material is preferably activated carbon fibers, optionally with a suitable binder and optionally with a catalytic material, in an aqueous slurry. The slurry dries and fills the slot 16 to remove excess material from the inner surface 40 of the tube 12.

The porous material for the slits may be long strands in the slits without felting or weaving into sheets. Figure 4 shows another embodiment which may be used for longitudinally extending slots in a pipe. As in the previously described embodiment of fig. 1, the longitudinally extending slots 16 in the tube 12 are filled with a porous material 18. But as shown in fig. 4, the difference is in the composition of the fibrous material 18. Rather than the felt shown in fig. 3, the fibrous material is longitudinally extending strands 126, the strands 126 extending along the length of the slots 16. The material of the strand may be glass, plastic, metal or carbon fibre, etc. The strands 126 are preferably activated carbon fibers. Sufficient strands in the slot 16 form a space or very long narrow hole 128 between strands that performs the necessary dual functions of sidestream smoke control and free-burn rate control. In order to increase the number of strands that can be placed in the slit while significantly increasing the surface area of the fibrous material, the strands preferably have a diameter that resembles hair in order to control sidestream smoke and achieve an acceptable pressure drop comparable to the smoking pressure of a conventional cigarette. The strands are placed along the slit and are maintained at different intervals along the slit to ensure that the strands do not spill over the slit when packaged or used.

A common means of controlling the free-burn rate is to restrict the flow of air to the burning coal tar that ignites the cigarette. By limiting the airflow, the free-burn rate of the cigarette is reduced as the burn rate slows. While this approach has been successful in controlling the free-burn rate, the device will restrict airflow when the smoker takes a puff.

However, the apparatus of the present invention does not control the free-burn rate in a conventional manner. Although the size of the porous material 18 and/or slots 16 will limit gas flow, the porosity and pore size are selected such that the tube 12 contains at least a portion of the hot, oxygen-free gas of combustion in the annulus 44 of the burning ember. As shown in fig. 2, the lit cigarette embers or coal tar 21 exit the tube 12 in the position shown in phantom. A typical soot cone 27 is located behind the advancing ember 21. The hot combustion gases are located in the annular space or gap 44 above, below and surrounding the cigarette where the combustion embers such as 23 and 25 are formed. Depending on the selected porosity of the openings 16 and/or the porous material 18, at least some, or substantially all, or most of the hot gases are retained in the zones 23 and 25 surrounding the combustion embers 21. To control sidestream smoke, the porosity and pore size are chosen to retain most if not substantially all of the hot gases, thereby forming oxygen-free gases in the region of the embers 21. The porosity of the tube 12 not only restricts airflow, but also maintains the hot, oxygen-free combustion gases, thereby reducing the burning embers, reducing the burn rate, and thus slowing the free-burn rate of the cigarette. The porosity of the material is selected to ensure that minimal air flows into the tube during periods when the cigarette is idle. This maintains the oxygen-free gas content in the coal tar-burning zone and maintains the free-burn rate of the cigarette at the desired minimum burn rate. When a smoker takes a puff from the device, gas is drawn through the openings in the tube and/or the porous material and air necessary to support combustion is supplied through the open end during smoking. Once the smoker stops smoking, the oxygen-free combustion gases contained in the burning ember zone immediately slow the burn rate and reduce the free-burn rate. It will be appreciated that the pore size in the tube may vary depending on a number of factors, such as the type of physical properties of the tube material, the composition and the type of pores. The reiterated background art demonstrates that multiple trials are required to select different pore sizes that provide the necessary porosity to control the free-burn rate and sidestream smoke.

This method of controlling the free-burn rate is different from prior devices which focused on controlling the air flow to the burning embers. The apparatus of the present invention retains the hot gases produced in the region of the combustion embers by creating a larger region in the annulus to accommodate a larger volume of hot gases relative to the fresh air required to support combustion. By virtue of the open annular space or being filled with a porous material, as will be explained with reference to fig. 5, a minimum but sufficient amount of air required to support and maintain minimal combustion during free-burn and smoking can be provided. While continuing to smoke, air is again drawn through the tube opening and the open end of the tube.

The porous material also has the ability to absorb or adsorb various particulate components and sidestream smoke aerosols, as well as to trap the material so that when the device is reused, the trapped smoke particles are not released to affect the flavor and taste of the fresh cigarette. The preferred carbon material for the porous material is a felt or a woven or woven sheet material commonly sold to be suitable for use in the slots 16 in the device 12. The carbon fiber material may cover the entire interior of the tube or only the narrow slits. Long strands of carbon fibers may also be placed therein along the slots 16 in the manner described with reference to fig. 4.

The openings in the tube of the embodiment of fig. 1 may be formed by laser cutting, high speed sawing, etching, punching, piercing, and the like. The porous assembly 18 is filled into the openings by dipping the tube into the fibrous material slurry to form a porous fibrous mat in the openings. When the slurry is dried in the pipe, excess fiber material in the pipe may be removed. It will be appreciated that the fibrous material may be precisely placed in the slot 16 as laser printing on paper and heated using a laser beam.

The tube 12 is made of a non-combustible material, preferably ceramic, high temperature plastic, treated or porcelain paper, synthetic porous wooden material or sheet material that is rolled and secured to a desired tube size. The interior may be coated with catalytic particles to promote oxidation of carbon and nitrogen containing gases released from the primary combustion of tobacco. Preferably, the outer portion of the tube 12 is white to simulate cigarette paper or, when using a cigar, is russet to simulate the wrapper of a cigar. Or the tube may be wrapped with cigarette paper having sufficient porosity. The filter portion 20 may be of conventional cigarette construction, but is of unitary construction to accommodate the filter 24 of the cigarette 14 within the bore 30. The filter portion 20 may be wrapped in suitable paper or the like so that the finished product in figure 1 looks like a conventional cigarette. When using cigars, the filter tip portion 20 may look like a conventional filter tip for cigars or a conventional mouthpiece typically used with cigars.

As shown in fig. 5, another configuration of the tube 48 of the device 10 is shown in other embodiments of the present invention. The tube 48 encloses the cigarette 50 and is provided with a suitable filter mouth 52. The tube 48 is made of a non-combustible porous flexible material of significant thickness. The thickness of the porous material is much greater than the thickness of the porous material used in the module 18 of the embodiment of fig. 1. Some of the composition of the porous material may be the same as the material of the component 18. Which may be a sheet or felt with holes therein, or woven or knitted carbon fibers, preferably activated carbon fibers, glass fibers, ceramic fibers, high temperature plastic fibers, metal fibers and the like, optionally including catalyst particles to enhance the continued burning of the gases emitted from burning the tobacco. The tubular assembly carries porous material 54 extending along the length of the tube 48 up to the filter line 56 of the filter mouth 52. As in the embodiment of figure 1, the porous material extends along the tube for the effective length of the tobacco rod to be lit, mimicking the same conditions as smoking a conventional cigarette. The filter house 52 is similar in construction to the filter house 20 of fig. 1. The filter portion 52 has a recessed portion 58 forming an annular groove 60 with a step or stop 62. The tube 48 has an end 64 and the tube 48 is sized to fit in the annular groove 60. The tubular member 48 is fully received in the filter house 52 with tipping paper 65 in a conventional manner. The cigarette 50 is inserted into the internal bore 66 in the manner described with reference to figure 2. The filter portion 52 supports the cigarette 50 and the tube 48, which contacts or engages the cigarette periphery, reinforces the support. Cigarettes may also be produced that do not have all the usual properties of conventional cigarettes such as firmness, strength, end ash, etc. The same applies to the device of figure 2, since the cigarette is enclosed in a tube and protected from the need for continuous knocking to remove the ash as when the device is not used for smoking. The tube of figure 2 may be provided with internal ribs to support the cigarettes concentrically within the tube. The device of the present invention may be used with cigarettes that are not manufactured in a somewhat conventional manner. A number of standard manufacturing processes such as the use of expanded tobacco, comminuted or reinforced stems, etc. to provide the desired firmness and appearance of the cigarette can be eliminated. In addition, the total amount of tobacco for fine cigarettes is small, so that lower quality tobacco can be used.

As shown in FIG. 5, the inner surface 68 of the tube 48 defines an inner diameter that is nearly equal to the outer diameter of the circumference 70 of the cigarette 50. The tube 48 fits over the cigarette 50 with the circumference of the cigarette substantially in contact with the inner surface of the tube 48. Since the tube 48 is made of a non-combustible material, it maintains its structural integrity as the cigarette is drawn and the cigarette is retracted into the tube. The tube 48 controls the free-burn rate of the cigarette while reducing sidestream smoke emitted from burning the cigarette. The porous material absorbs and traps smoke-like particles and aerosol particles of sidestream smoke, and therefore may retain sidestream smoke within the tube. In addition, if the catalyst particles are implanted in a porous tubular material, the odour-producing components of the smoke may be oxidised to tasteless or good tasting components.

The porous material is in the form of a mat or sheet or the like which captures and retains particles of particulate smoke so that they are not released during smoking of a new cigarette in the device when the device is reused. In addition, the porosity of the porous material is selected to control airflow and retain hot combustion gases in the burn cigarette ember region, so as to desirably reduce the free-burn rate, enabling smoking of the cigarette the same number of times as a conventional cigarette.

The tube 48 may be made of a sheet or felt. Or may be made from multiple layers of sheets or mats of porous material to produce a tube of desired thickness. The tube may include an outer coating or wrapper to give the exterior of the tube a color like a cigarette or cigar. The coating or wrapper is porous but does not affect the porosity of the tube 48, which is desirable for controlling the free-burn rate and sidestream smoke. Other types of exterior coatings are described with reference to fig. 12 and 13.

The tube 12 in the embodiment of fig. 6 is provided with openings for controlling the free-burn rate and reducing sidestream smoke. By selecting an appropriate opening size, such as the width of slot 16, and appropriately sizing annulus 44, sidestream smoke and free-burn rate can be controlled to an acceptable level. Sidestream smoke is reduced to a less complete extent than in a device with modules 18 in slots 16. The slot is smaller than the slot 16 of fig. 1 used to control the flow rate of air into the annulus 44. The opening in the tube member may also be a hole, preferably a circular hole. The opening is formed precisely in the tube, reducing the size of the opening to control the free-burn rate. The openings may be formed in the tube by laser drilling or the like and are sized to allow a portion of the sidestream smoke to pass through but will substantially reduce the sidestream smoke released. Fig. 6 shows the permanent connection of the filter mouthpiece 20 to the tubular device 12. The filter portion 20 may comprise an annular filter-like element 72 having an internal bore 74 for receiving a filter 76 of a cigarette 78. The annular assembly 72 is secured to the tube 12 by a suitable filter wrapper 80, the wrapper 80 giving the tube the appearance of a finished cigarette and permanently attaching the filter mouth 20 to the tube 12.

Figure 7 shows an exploded view of the device of figure 1 in which the mouthpiece 20 is removable from the tube 12 to expose the cigarette 14 and the filter of the cigarette is withdrawn from the mouthpiece 20. The filter 24 of a new cigarette or its tobacco rod may be inserted into the mouthpiece portion 20 and the tube 12 fitted over the annular groove 32 to assemble it.

Figure 8 shows an alternative construction of the device 10 in which a mouthpiece 82 is attached to the tube 12. The mouthpiece 82 receives a mouthpiece of tobacco material into the body portion 84 and has an annular groove over which the tube 12 is fitted. The mouthpiece 82 has a generally narrow portion 86 for comfort in the mouth of the smoker.

The filter plug portion 20 may be similar to a conventional cellulose acetate cigarette filter with a filter insert 72 as shown in figure 9. The annular end 86 of the groove 34 is insertable into the tube 12 to avoid drawing gas in the annular space between the periphery of the cigarette 14 and the interior 40 of the tube 12 into the filter mouth portion 20. Preferably, a controlled amount of air is drawn into the filter mouthpiece 20, which may be achieved by conventional venting or air circulation techniques used in the filter mouthpiece 20. The shoulder 34 of the filter sock 20 has a recess or aperture 73 formed by the end 86. The tobacco rod end 75 is inserted into the aperture 73 to secure the tobacco rod 22 in the spiral filter mouth 20 to form a cigarette component. The tube 12 is fitted over the circumferential groove 34 to form the smoking device 10. The device is disassembled accordingly for insertion of a new tobacco rod 22.

A further modification of the construction includes the provision of a ring 88 at the open end 85 of the tube 12, as shown in figures 10 and 11. The band has an opening 90 that is approximately the same size as the diameter of the cigarette end 26. The ring 88 in one embodiment of the invention is used to retain soot in the tube 12 during smoking. The cigarette end 87 is positioned slightly inward of the ring 88 to light the cigarette in the installed device.

Fig. 12 and 13 show other variations of the device for controlling the free-burn rate in combination with a housing. The tube 12 of fig. 12 is provided with a housing 92. The housing 92 has a plurality of openings 94 therein. The number and size of these openings are sufficient to allow free circulation of air so as to supply a greater volume of air than is required to burn the cigarette. To control air circulation, as well as to control the free-burn rate and reduce sidestream smoke, a tubular sheet 96 of porous material is provided. The layer may be located on the inner surface of the perforated tube 92 and may optionally be secured thereto. The porous material layer 96 is porous for desirably controlling gas flow and retaining hot combustion gases. In addition, the porous material can absorb and trap smoke. As with the other embodiments, when the device 10 is reusable, the porous material 96 retains the trapped smoke and does not release it when a new cigarette is smoked. Alternatively, the porous material 96 may be formed as a replaceable tubing that is inserted into the tube 12.

A thicker inner layer 98 of porous material is provided in the embodiment of fig. 13. The thickness of this layer corresponds to the thickness of the tube 48 in fig. 5. The housing 100 may be a porous outer coating of high porosity paper, ceramic fiber, high temperature plastic, etc. As shown, the overpack 100 is provided with apertures, shown as openings 102, that are large enough in number and size not to interfere with the functioning of the tubular porous member 98. Inner tubular member 98 contacts the outer circumference of cigarette 14 in the manner described in the embodiment of figure 5. This is in contrast to the embodiment of figure 12 where the perforated tube member 96 is spaced from the circumference of the cigarette 14 to form an annular space 104, which is similar to the embodiment described above with reference to figure 2 in the embodiment of figure 12. The function of the tube 98 is the same as the embodiment described with reference to fig. 2. The burning coal tar with the soot enters the interior of the tube. The porous material 98 controls the gas flow and preferably retains a majority of the hot oxygen-free combustion gases in the coal tar-burning zone to desirably control the free-burn rate.

In the embodiment of figures 12, 13 and 15, the filter 24 of the cigarette 14 extends through the filter plug portion 20. The filter housing 20 may be provided with a receiving portion 95 for the filter 24, which may be porous, since it need not be filtering. The receiving portion 95 is secured to the tube 12 by tipping paper 97.

Fig. 14 shows another embodiment of the tube 12. The tube 12 is made of a spiral wrap 106 of non-combustible material. The interior 108 of the spiral wrap is provided with an intermediate material to fill the helical gap 110 with a composition for controlling the free-burn rate. As shown in fig. 15, in one embodiment, the spiral wrap 106 secures a tube 112 of porous material within. The tube 112 may function as described with reference to figures 12 and 13 with an annular gap 114 between the tube 112 and the periphery of the cigarette 14. Alternatively, as shown in figure 16, the cigarette paper 106 may have a wrapper 116 of porous material secured to its inner surface 108, which serves the same purpose as the porous material used for the tube 112. The cigarette paper 106 may be made of any suitable non-combustible material, preferably ceramic fibers. The tube 108 or inner wrapper 116 is also made of a non-combustible porous material, preferably activated carbon fibers.

The embodiment of fig. 17 may include a tube 12 having any of the structures described above with a temperature indicator 118 disposed on a surface thereof. The temperature indicator may be formed by a separate unit 120 that changes color depending on the temperature. When the burning coal tar of the cigarette burns inside the tube 12, the temperature in this region changes the colour of the individual units 120, so that the smoker can see traces of the movement of the coal tar towards the inside of the tube 12, and when the last unit 120A indicates that the burning coal tar is reaching the filter, the smoker stops the device 10 from smoking. The temperature indicator greatly facilitates use of the device 10 and avoids the smoker drawing on a cigarette that has been extinguished in the tube 12 by encountering the filter. In a disposable device, the tube 12 may be wrapped in porous cigarette paper. As the coal tar of the cigarette burns inwardly of the tube 12, the cigarette paper will slightly turn color, indicating the location in the tube 12 where the coal tar was burned. Alternatively, the tube 12 may be made of a material that is non-combustible and discolors when the burning coal tar moves inward. The adhesive used to seam the outer cover of the device 10 may be a heat sensitive material. The material will change color as the burning coal tar moves inwardly of the tube 12. The wrapper is made of a non-combustible heat resistant material, such as ceramic fibre, so that the device can be reused. The cementitious material is made of a composition that repeatedly changes color as the burning coal tar moves toward the interior of the tube 12.

In order to make the cigarette filter and the mouthpiece portion contact each other distinctively, as shown in fig. 18, the cigarette filter and the mouthpiece internal structure are formed to be fitted to each other. Filter portion 24 of cigarette 14 is provided with longitudinally extending grooves 122. The mouthpiece filter portion 20 is provided with a detent 124 extending longitudinally inwardly of the inner bore 30. The recess 122 is shaped to mate with the catch 124 to ensure that only cigarettes designed to mate with the mouthpiece 20 can be placed in the device for use. By virtue of the above design it is possible to ensure that, for example, the correct length of cigarette is used in the filter mouth 20 with the correct size of filter or the correct brand of cigarette is used in the device.

Another embodiment of the tube 12 is shown in fig. 19, which shows the tortuous path of air flow into the tube and sidestream smoke flow to the exterior of the tube. Three concentric tubes surround the cigarette 14. The two first inner tubes 130 and 132 are provided with longitudinal slits which are identical to the slits of the outer tube member 12. The slots 134 of the inner tube 130 are offset from the slots 136 of the adjacent tube 132. An annular space 138 is formed between the inner surface of the tube 130 and the periphery of the cigarette. A narrow gap 140 is formed between the tube members 130 and 132 and a narrow gap 142 is also formed between the tube member 132 and the tube member 12. Such narrow gaps between the pipe elements control the flow communication between the openings of the respective pipe elements forming the meandering channel to a certain extent. The tube 12 is provided with conventional felt, woven or standard fibers to control free-burn rate and sidestream smoke. Sidestream smoke emitted from a burning cigarette 14 flows outwardly through the slit 134, through the tortuous path between the tubes 130 and 132, out through the openings 136 offset from the openings 134, and back through the space between the tubes 132 and 12 until encountering the porous material 18 in the outer slot 16 of the tube 12. By providing this tortuous flow path for the sidestream smoke, the filtration is enhanced and further cooled, making the exterior of the tube 12 comfortable to the touch and reducing the size order of the circumference of the cigarette.

Fig. 20 and 21 show another embodiment of the opening of the tube 12. The tube 12 is provided with holes 143 formed in a particular manner to enhance control of sidestream smoke while controlling the necessary free-burn rate. As shown in the cross-sectional view of fig. 21, an aperture 143 is formed in the wall of the tube 12 by, for example, punching or perforating the tube 12 to form barbs or projections 144 of fibrous material that project toward an inner diameter 146 of the tube 12. The tube 12 is typically made of a fibrous type material and the barbs 144 project the fibers 145 inwardly of the tube to further enhance filtration and to treat sidestream smoke that is intended to flow outwardly from the apertures 143.

As shown in figure 21, barbs 144 are positioned to keep cigarette 14 concentric with tube 12, thereby forming gap 44. Positioning the cigarette in the tube by the barbs 144 enhances the sidestream smoke control properties of the barbs, the smoke passing through the barbed fibers 145 before the gaseous products are emitted through the apertures 143. It has been found, quite surprisingly, that by forming such holes in the tube 12 as described above, not only is the sensation of smoking very close to or the same as that of ordinary smoking, but the surrounding taste of the cigarette is normal and does not give off a strange taste.

Fig. 22 shows another embodiment of the tube member 12 which is thinner or has a thickness substantially the same as the thickness of the other tube member shown in fig. 20. The tube end 148 represents this thickness. An annular gap 150 exists between the tube 12 and the cigarette 14. The capillary members are constructed of stacked sheets of ceramic fiber material that are lightly calcined or treated in a furnace to remove most of the binder material from the ceramic fibers by combustion. The sheet is porous as the burning removes the binder from the sheet, forming a plurality of interconnected voids, thereby forming a porous sheet. The porous sheet may be rolled several times to form a tube. The resulting tube is provided with very small holes that allow the escape of invisible volatiles while providing the necessary control over sidestream smoke and free-burn rate of burning cigarette 14. By appropriate selection of the proportions of ceramic fibers and combustible binder used to make the base sheet, the desired amount of organic binder, such as cellulose, can be removed by controlling the calcination of the formed tube, and heating the material to produce the desired porosity. The sheet is rolled to form a tube 12, which is then calcined to form a matrix of interconnected pores in the tube, which provide the desired porosity and pore size to control sidestream smoke and free-burn rate.

Figure 22 shows a particular arrangement of cigarettes 14 in the tube 12. The end 26 of the cigarette is spaced inwardly from the end 148 of the tube. The cigarette end 26 is located inside the tube 12 and draws the hot gases of the flame 151 of the lighter 153 into the tube to ignite the cigarette 14. For example, end 26 may be located half the length of the cigarette from tube end 148. The recessed positioning of the cigarette ends reduces the amount of sidestream smoke released when the cigarette in the device 10 is lit.

Various configurations of the filter or mouthpiece portion of the device 10 have been described. Figures 23 and 24 show an alternative construction of the filter mouth 20 which includes a sleeve 160 which may be cylindrical to form a cylindrical shoulder 162. Because the inner surface 164 of the tubular member is substantially the same diameter as the shoulder 162, the cylindrical tubular member 12 is frictionally mounted on the sleeve shoulder 162. The sleeve has an annular flange 166 forming a stop against which the pipe end 168 abuts. The filter tipping paper 170 is wrapped around a thin insert 172 which can withstand compression in this region of the filter to ensure clearance 190. Tipping paper 170 and sleeve 172 may be glued to the tube to fully mount the filter on the tube. Alternatively, the tube may be separate from the filter to facilitate insertion of a new cigarette. Where it is desired to ensure a certain amount of ventilation in the mainstream smoke of a cigarette, ventilation holes may be provided in the insert 172 in the usual manner.

The sleeve 160 is provided with an aperture 174 which frictionally engages an end 176 of the tobacco material 22. The friction fit of the tubular tobacco material in the sleeve 160 holds and positions the tobacco material in the tube 12. The sleeve 160 may be integral with or attached to a tubular porous support structure 178, which structure 178 may be a wire mesh. The porous tubular structure 178 supports a microfiber material 180. The above-described microfibrous material can be made by the process described by the applicant in canadian patent 1057924, U.S. patent 3882877 and published international application WO 90/09741. The above references describe the use of the microfibrous material in cigarette filters. The microfiber material is very effective in filtering tobacco smoke with little pressure drop as the smoke passes through the filter. The smoke enters the tubular filter 20 through the central aperture 182 as indicated by arrow 184. The smoke passes radially through the first tubular filter 180 as indicated by arrow 186. As the filter filters particles from the cigarette smoke, the smoke continues to flow down the tubular filter 186 and thus does not interfere with the effectiveness of the filter material. A second tubular filter 188 of a second filter material may optionally surround the microfibrous material 180. Preferably, the second tube 188 is concentric with and overlaps the first tubular filter 180. The second tubular filter is preferably made of carbon, particularly activated carbon, to remove particulates from the smoke stream and to modify the flavor of the cigarette smoke. The second tubular filter 188 is located in the annular space between the first filter 180 and the plastic insert 172. Due to the position of the second tubular filter, an annular space 190 is formed between the second filter and the tipping paper. The smoke flows in the direction of the continuation of arrow 186 along annular space 190 and around stopper 192 with an annular array of holes 194 allowing the smoke to flow into enclosed space 196. The enclosed space 196 allows smoke to pass through the inner surface 198 of the filter insert 200, allowing smoke to flow through the filter insert 200 in the direction of arrow 202. The stopper 192 in this embodiment closes the end 204 of the first filter tube member 180 to force smoke through the microfiber filter material when a smoker draws on the cigarette. The structural portion of the filter plug is particularly useful for directing mainstream smoke emitted by the slim cigarette 14 toward the multi-component filter element for good filtration and for generating mainstream smoke in the filter plug which is comfortable to the smoker and provides a normal flavor, mouth feel and pressure differential.

Referring to fig. 25, there is shown a preferred embodiment of the filter portion structure of fig. 23. The means for supporting the first tubular filter material of microfiber material in fig. 25 is an injection molded piece 206. The member 206 includes a sleeve 160 with an external shoulder 162, a stop 166, and an internal bore 174. The support 178 for the first filter material includes a plurality of slots 208 extending along its length to allow cigarette smoke to flow radially through the slots 208 through the openings 182 in the tubular support. As described above, the stop 192 includes a flat portion 210 that blocks the end of the tubular support 178 for the first filter material. In addition, the stopper 192 includes a button 214 that forms a spacer that separates the filter insert 200 of fig. 24 from an inner surface 216 of the stopper, as shown in fig. 24, to form the enclosed space 196. As shown in fig. 25, the button 214 is located at the periphery of the stop 192. In addition, fig. 25 shows the apertures 194 between the button supports 212 through which tobacco smoke flows into the enclosed space 196.

As mentioned above, the tobacco material may be a tobacco rod formed in a porous mesh and manufactured by Rothmans, Benson & Hedges Ins. Sold under the trademark "Custom Cut". If only the tobacco rod is smoked, it will not be smoked because there are too many holes. The tube 12 is adapted to reduce the porosity of the web containing the tobacco rod so that it is smokable. This can also be achieved by incorporating an inner sheath in the tube 12 into which the tobacco rod is wrapped or otherwise wrapped as in the embodiment of figures 5 or 13 and contacting the periphery of the tobacco rod to reduce porosity and render the tobacco rod smokable. Other variations for normally non-smokable products include modifying the cigarette filter 24 of figure 2 so that the filter wrapper or outer portion is so porous as to interfere with smoking of the lit tobacco material. However, when the porous filter 24 of the cigarette 14 is inserted into the filter portion 20, the interior of the pores in the filter portion 20, such as shown in figure 12, closes the exterior of the porous filter so that the cigarette becomes smokable. Another embodiment is to place a coarse, unfiltered, rolled tobacco rod into the filter plug 20, wherein the tobacco rod is too coarse to be smoked normally, thereby creating the desired filtered, smokable flavor and mouth feel.

A device with sufficient safety characteristics surrounding a cigarette or cigar should be capable of being accidentally placed on a combustible material. The non-combustible tubular member contains the burning coal tar of the cigarette and prevents direct contact of the burning coal tar with potentially combustible materials. This design greatly reduces the chance of accidental fires due to burning cigarettes. In addition, the annular space of the tube and its thickness are such that the temperature of its outer diameter, although hot to the touch, does not scald the smoker. Although the tube becomes hot during smoking, it is not so hot as to scald the user. The end of the tube is preferably aligned with the end of the tobacco rod or even flush with the end of the tobacco rod. Because the tube is non-combustible, the device end can be fired to light the cigar or cigarette end in order to initiate a smoke draw.

As mentioned above, another advantage provided by various embodiments of the present invention includes catalytic materials or particles that convert odorous gases into less tasting or tasteless substitutes. Depending on the effectiveness of the device in controlling sidestream smoke, it can be seen that the component escaping from the tube is a visually odourless gas. It is therefore important to reduce the odour by a step of diffusing certain smoke constituents into a visible gas to mask it or by reducing it so that it is not detected during smoking. During a typical smoking event, a burning cigarette emits a large amount of odorous gases, however, the strong odor emitted by the odorous gases is masked by all other smoke components emitted by the sidestream smoke. However, it has been found that suitable catalysts made from noble metals, rare earth metals, and the like, and mixtures thereof, may be the catalyst or the metal in the catalyst. Preferred metals include platinum or cerium, which can be used to oxidize odorous gases, making them odorless. The catalyst particles can be added to various pipes. They may be incorporated into the porous material and placed in various openings in the pipe, for example, when making felt 18, catalyst particles may be incorporated into the felt. The catalyst material may be added to the inside or outside of the tube or to the fiber strands adhered in the slit of the tube. A film of catalytic material may be added to the interior of the tube or to the opening 104 of the embodiment shown in fig. 12 and 13. Catalytic material may be added to the openings 104 as a heat treated material to further control sidestream smoke and free-burn rate when the catalyst is in a region where the catalyst is properly oxidizing the gaseous species in the smoke particles that permeate the tube.

The inclusion of catalytic material in the material from which the tube is made, such as in the process of making the mat 18, can provide significant advantages in converting the odorous visible gas to an odorless gas or to a gas with an acceptable taste, while providing additional control to form the desired predetermined porosity in the tube. The above advantages are particularly apparent when using the catalyst in the manufacture of the calcined pipe element shown in figure 22. The tube may be formed by rolling two or more sheets of ceramic matrix. The sheets may be formed in the usual manner by forming a slurry of ceramic precursor materials including clays, alumina sol binders, various types of organic binders, alumina and other common components included in ceramic precursors. To prepare the above sheet, the slurry containing the high solid content is spread out according to a conventional papermaking method, rolled and dried to prepare a ceramic precursor sheet. The sheet is rolled one or more times according to its thickness, as described above, to form a tube having the desired thickness. In making the sheet, catalytic material and/or catalytic precursor material may be added to the slurry to dissolve or disperse in the slurry, and the catalytic material may be incorporated into the sheet material in the form of a catalyst or precursor when it is rolled into a tube and during the light calcination of the tube. The addition of the catalytic material provides better control of the formation of the desired pores in the tube, and the presence of the catalytic material in the tube enhances the oxidation of the odorous gas as it passes through the tube. This is more oxidizing than coating the inside of the tube with catalytic material.

A variety of catalytic materials may be used, such as those based on precious metals, rare earth metals, etc., including platinum or cerium, and the preferred parent catalytic material added when making the pipe is a ceria catalyst parent, known as hydrated ceria. This Material is available from Advanced Material Resources of Ontario, Toronto, Canada. The addition of the hydrated form of cerium oxide to the ceramic precursor slurry causes its crystalline structure to change during the mild calcination process. The cerium oxide is dehydrated to form another crystalline cerium oxide in the calcined material, usually in microcrystalline form. During the conversion of the hydrated ceria to a ceria catalyst, the resulting ceria catalyzes the oxidation reaction, i.e., the combustion of the binder material, particularly when the binder is organic, such as a cellulosic material. Upon calcining the tube, the catalyzed oxidation of the binder material increases the size of the pores formed in the tube. With the catalytic cerium oxide, the degree of oxidation of the cellulosic material can be controlled to form a desired pore size in the material to produce a desired predetermined porosity in the tube.

Another advantage of incorporating a cerium oxide catalyst in the tube is that it enhances the oxidation of the non-visible odorous volatiles, thereby reducing the unpleasant taste of the cigarette. It has been found that invisible volatile components include ammonia and acetaldehyde. Even in the case of high concentrations of carbon monoxide intended to be oxidized as a catalyst, the presence of cerium oxide surprisingly allows the oxidation of ammonia and acetaldehyde components which, when smoked, convert them into odorless or at least more normal tasting components. In view of all the combustion compounds emitted by burning cigarettes, it is even more surprising that the cerium oxide catalyst is particularly effective in neutralizing the taste of ammonia permeating through the porous tube in the invisible volatiles.

Although the addition of the cerium oxide catalyst to the tube not only catalyzes the oxidation of volatiles but also enhances control of the porosity of the tube, it should be understood that the cerium oxide catalyst may also be sintered as a powder for application to the interior or exterior of the tube or into the opening of the tube, or onto a mat placed into the opening of the tube, as described above with reference to other types of catalysts.

The following illustrates various aspects of several embodiments, which are not intended to limit the scope of the claims.

The cigarette used in the device has a diameter of 3.5-10mm, preferably about 4-8 mm. Cigarettes with a diameter of 4-5mm give good results. In order to develop the desired flavor and mouth feel in mainstream smoke, particularly with thinner cigarettes, the cigarette ingredients may be modified according to the blending method described by the applicant in us patent 5524647. The packing density of cigarettes, even finer cigarettes, is not specific. With a typical packing density, e.g., 200-300mg/cm³. The device allows for a finer cigarette to be smoked a desired number of times, so that a packing density of less or more than usual is not necessary. The cigarette may be wrapped in any cigarette paper having a suitable porosity, which may be greater than the porosity of the tube. The cigarette paper may have a porosity of 10-100Coresta units, preferably 46-60 Coresta units. Vanillin and other flavor additives can be added to the cigarette paper. The free-burn rate under normal smoking conditions, i.e. a thin cigarette without a tube, is quite high. For example, a cigarette with a conventional furnish, packing density, and 5mm diameter of wrapper would have a free-burn rate of about 5 mm/minute. The free-burn rate of cigarettes with a diameter of 4mm increases significantly, 8-10 mm/min. This rate is much greater than a conventional 8mm diameter cigarette with a free-burn rate of about 3 mm/minute. It is surprising that a thin cigarette of ordinary length can be made smokable 8-10 times using the above device while retaining the desired mouth feel and flavor.

Physical parameters of the tubular that achieve the above properties include a porosity value of the tubular of about 20 to 60Coresta units. When the device is installed, the pressure differential across the device is between 0.5 and 25cm of water, preferably between 3 and 14cm of water, and most preferably between 5 and 10cm of water. The inner diameter of the tube is about 7-10mm and the wall thickness is about 0.25-0.5 mm. The cigarette is preferably 4 or 5mm in diameter, thereby forming a gap of about 0.5mm to 3mm, preferably 1 to 2.5mm, most preferably 1.5 to 2.5 mm. With the gap between the cigarette and the tube, the temperature of the cigarette is maintained at about 600-800 ℃ during smoking and at about 400-600 ℃ during idle. The tube is maintained at a relatively low temperature range of 120 ℃ and 200 ℃. The tube is wrapped in a plain cigarette paper having a porosity of 10-100Coresta units, preferably 40-80Coresta units, and the porosity of the cigarette paper is greater than the porosity of the tube to ensure that the cigarette paper does not interfere with the control of the free-burn rate by the tube pores, under which conditions the exterior temperature of the tube is optimal. It has been found that if a catalytic material, such as cerium oxide, is applied to the exterior of the tube, combustion of the cigarette paper is catalyzed, thereby increasing the discoloration of the cigarette paper with each puff to clearly indicate the location in the tube where the coal tar is burned. Due to the above pore range of the tube member and the cigarette paper, wherein the pores are evenly distributed on the material, no visible sidestream smoke passes through the tube member, only invisible volatiles pass through the tube member, which volatiles can be converted by the catalyst into tasteless components.

The pressure drop of the preferred cigarette filter configuration of figure 24 is very small, but half the pressure drop of a conventional filter, about 1-3.

The preferred catalytic material is a slightly calcined hydrated cerium oxide (Ce)₂O₃×H₂O), which is obtainable from the above-mentioned AMR of toronto. The catalyst may be added during the manufacture of the sheets, wherein the slurry of the compound, which is about 90-95% by weight water, includes glass fibers and inorganic materials such as microfibers, clay, talc, and organic binders such as acrylonitrile and acrylic based emulsions. The slurry may include cellulosic fibers in order to strengthen the wrapper prior to calcination. In the dried cigarette paper, the inorganic matter accounts for 90 percent of the weight of the cigarette paper. The wrapper is typically 5-10 mils (mil) thick and is wound 2-3 times to make the tube. The tube was lightly calcined by heat treatment at a first stage temperature of about 220-260 deg.C and a second stage temperature of 400-600 deg.C in an oxidizing atmosphere. Staged heating ensures that volatiles are released without blowing the material. The catalyst is added in an amount of about 0.5 to 10% by weight of the dried sheet. The catalyst precursor is preferably present in an amount of 1-5% by weight, most preferably in the range of 1-3%. The addition of suitable organic materials can be formed in the pipeAnd (c) ideal porosity, wherein the pore size of the porosity is capable of restricting gas flow to control free-burn rate and retain hot combustion gases in the tube. The optimal density of the cigarette paper can be about 0.70gm/cm by adding more organic matter to the slurry³-0.80gm/cm³。

The outer diameter of the tube in the preferred embodiment of the invention may be the same as a conventional cigarette so that the overall appearance of the device with the fitted filter portion resembles a conventional cigarette. By controlling the free-burn rate, the slim non-conventional cigarette used in the device may contain considerably less tobacco, perhaps up to 3/4, and in a preferred embodiment of the invention less than 2/3. The free-burn rate is controlled so that the cigarette burns significantly more slowly during periods of inactivity and the same smoking times are achieved with the device of the invention as with a conventional cigarette. The amount of tobacco used is significantly reduced, which is typically wasted in conventional sized cigarettes, and significant cost savings are now realized in the cigarette making process, while still retaining other advantages and properties of conventional cigarettes.

Preferred embodiments of the present invention are described herein. It will be understood that various modifications may be made without departing from the spirit of the invention and the scope of the appended claims.

Claims (44)

1. A device (10) for reducing cigarette sidestream smoke and reducing the free-burn rate of a burning cigarette (14), said device comprising:

i) a non-combustible porous tube member (12) surrounding an effective length of tobacco material (22) of cigarettes (14) in said tube member (12), said tube member (12) having an open end adjacent said cigarette end (26) for lighting said cigarette end (26) and allowing air to enter; and

ii) said tube (12) carrying a means (16) for reducing sidestream smoke emitted from a burning tobacco material (22) while reducing the free-burn rate of the burning tobacco material (22) to increase the number of times the burning tobacco material (22) can be smoked, the means for reducing sidestream smoke and reducing free-burn rate comprising a predetermined aperture of the tube (12) distributed at least along the length of the tube containing an effective length of tobacco material (22), the predetermined aperture of the tube (12):

a) retaining at least part of the oxygen-free combustion gas in the tube (12) to reduce smoke particles released through the opening (16); and

b) the inward gas flow is restricted to reduce the free-burn rate of the cigarette.

2. A device according to claim 1, wherein the inner diameter of the tube (12) is greater than the outer diameter of the cigarette (14) so that an annular space (44) is formed between the inner surface (40) of the tube and the periphery (42) of the cigarette.

3. A device according to claim 2, characterized in that the opening (16) is slit-shaped.

4. A device according to claim 2, characterized in that the openings (16) are slits covered with a porous felt (18).

5. A device according to claim 4, characterized in that the felt material (18) consists of carbon fibers, glass fibers, ceramic fibers, high temperature plastic fibers or metal fibers.

6. A device according to claim 2, characterized in that the openings (16) are grooves covered with carbon fibre filaments (126) extending along each groove.

7. A device according to claim 2, characterized in that said opening (16) is a hole (102, 143) through the wall of the tube, the diameter of which hole forms said predetermined aperture.

8. A device according to claim 7, characterized in that the holes (102, 143) are located in the tube wall and form fibrous protrusions (144) in the tube, which protrusions centre the cigarette in the tube (12).

9. A device according to claim 8, characterized in that the tube (12) consists of ceramic fibres.

10. A device according to claim 1,

the tube (12) includes a body portion of porous material (54) having a predetermined porosity, the tube surrounding the cigarette and being in contact with the cigarette (50).

11. A device according to claim 10, wherein the porous material (54) comprises a felt of carbon, glass, ceramic, high temperature or metal fibres.

12. A device according to claim 11, wherein said material (54) is a felt of activated carbon fibres.

13. A device according to claim 10, wherein the tubular body portion comprises a plurality of layers of fibrous material.

14. An apparatus according to claim 2, wherein said tubular member (12) is lined with a porous fibrous material (98).

15. A device according to claim 14, characterized in that the fibre material (98) is carbon fibre, glass fibre, ceramic fibre, high temperature plastic fibre or metal fibre.

16. A device according to claim 14, wherein the fibrous material (98) is activated carbon fibre.

17. An apparatus according to claim 2, characterized in that the tube (12) has a wall (106) of a spirally wound non-combustible material, the spirally wound material being provided with narrow grooves (110) which are covered with a porous felt material (112, 116) for forming the openings, the felt material being made of carbon fibers, glass fibers, ceramic fibers, high temperature plastic fibers or metal fibers.

18. A device according to claim 17, wherein the felt material (112, 116) is formed from activated carbon fibres.

19. A device according to claim 2, characterized in that the opening (16) is formed by heat treatment of a tube of ceramic precursor material.

20. A device according to claim 19, wherein the tube (12) is formed by winding a sheet of ceramic precursor material and the hole is formed therein by heat treating the tube.

21. A device according to claim 20, wherein said sheet comprises a combustible binder which evaporates during the heat treatment to form said apertures.

22. A device according to claim 10, wherein the body portion of the tubular member (12) comprises a plurality of coaxial tubes (12, 130, 132) each having a plurality of openings (134, 136), each tube being superposed on an inner adjacent tube, the openings of each tube being offset from each other to form a tortuous path through the openings of the tubular member.

23. A device according to claim 22, characterized in that the opening of the outermost one (12) of said coaxial tubes (12, 130, 132) is covered with a porous felt material.

24. An apparatus according to any one of claims 1 to 23, wherein the tubular member comprises a catalyst.

25. An apparatus according to any one of claims 1 to 23 wherein the tubular member comprises a catalyst selected from the group consisting of precious metals, rare earth metals and mixtures thereof.

26. The apparatus of claim 25, wherein the catalyst is a platinum or cerium based catalytic material.

27. The apparatus of claim 26, wherein the catalyst is cerium.

28. A device according to claim 24, wherein the catalyst is disposed in the tubular member (12) or coated on the inner surface of the tubular member.

29. The apparatus of claim 28 wherein said catalyst is cerium oxide and is added during the mild calcination of said tubular member, said tubular member being comprised of a slurry of a ceramic precursor component to which is added hydrated cerium oxide, said ceramic precursor being calcined to convert said hydrated form of cerium oxide to ceramic oxide with the formation of pores in said tubular member.

30. A device according to any one of claims 1 to 23, wherein the tubular member (12) is wrapped in porous cigarette paper.

31. A device according to any one of claims 1 to 23, wherein the tubular member (12) is wrapped with a porous outer sheath, the outer sheath including a temperature responsive strip for visually indicating the location of burning cigarette coal tar in the tubular member.

32. A device according to any one of claims 1-23, wherein the tube accommodates a cigarette (14) having a diameter of about 4-8 mm.

33. A device according to claim 32, wherein the diameter of the cigarette (14) is about 4-6 mm.

34. A device according to claim 33, wherein the diameter of the cigarette (14) is about 4 mm.

35. A device with a device according to any of claims 1-23, wherein a cigarette (14) is accommodated, said cigarette (14) having a diameter of about 4-8 mm.

36. A device according to claim 35, wherein said cigarettes (14) have a diameter of about 4-6mm, said means for reducing sidestream smoke and decreasing free-burn rate causing said fine cigarettes (14) to be normally smoked 8-10 times per cigarette (14).

37. A device according to claim 35, wherein said cigarette (14) is inserted into and supported by a filter element (20) attached to one end (168) of said tube (12), said filter element centering said cigarette in said tube (12).

38. An apparatus according to claim 37, wherein a portion of the filter element (20) is friction fitted into the tube (12) and tipping paper (80) secures the filter element (20) to the tube (12).

39. A device according to any one of claims 1 to 23, further comprising a mouthpiece (20) for the device, the tubular member (12) being adapted to receive a thin cigarette (14) of about 4 to 6mm diameter, the mouthpiece (20) having an inlet end and an outlet end (202), the inlet end comprising an annular sleeve (160) with a central aperture (174) to receive one end of the cigarette (22), the annular sleeve (160) having an outer shoulder (162) on which the tubular member (12) is frictionally mounted, the central aperture (174) communicating with a first inner tube (180) of first filter material, the closed end (192) of the tube (180) being opposite the end communicating with the tube and the central aperture (174) of the sleeve, an annular space (190) being formed outside the first tube (180), a filter insert (200) is disposed downstream of the annular space (190) and is inserted into the outlet end (202) of the filter, the components between the filter insert (200) and the first tube (180) forming an enclosed space (196) for delivering filtered smoke from the annular space (190) to the filter insert (200).

40. A device according to claim 39, wherein a second tube (188) of a second filter material is centrally located in said annular space around said first tube (180).

41. A device according to claim 40, wherein the filter material of the first (180) and second (188) tubes is selected from the group consisting of: a cellulosic material, a glass ceramic or carbon fiber felted material, an activated carbon material, a microfiber material, and any of the foregoing materials with a catalytic material added.

42. A device according to any one of claims 1-23, wherein an annular space (44) is provided between the inner surface (40) of the tube and the periphery (42) of the cigarette, said annular space (44) defining a gap of about 0.5-3 mm, preferably about 1.5-2.5 mm.

43. A device according to any one of claims 1 to 23, wherein a cigarette (14) inserted into the tube (12) is not originally smokable but becomes smokable after insertion into the tube (12).

44. A device as claimed in any one of claims 1 to 23, wherein a cigarette (14) inserted into said tube (12) is provided with a filter element (20) sufficiently porous to render the otherwise non-smokable cigarette smokable after insertion into the mouth filter portion of said tube.