GB2491358A

GB2491358A - Smoking device for generating an aerosol

Info

Publication number: GB2491358A
Application number: GB201109066A
Authority: GB
Inventors: Liu Chuan; Garrick Thorn
Original assignee: British American Tobacco Investments Ltd; British American Tobacco Co Ltd
Current assignee: British American Tobacco Investments Ltd
Priority date: 2011-05-31
Filing date: 2011-05-31
Publication date: 2012-12-05
Also published as: GB201109066D0

Abstract

A holder (1, Fig. 1) for a smoking article 26 comprises a receptacle for receiving the smoking article, a mouthpiece 4 and a passageway 32 to supply a flow of smoke from the smoking article to the mouthpiece. The smoking article has a filter 24, whilst the holder also includes a filtrand release device for operating on the filter to partially release the filtrands therefrom into the flow of smoke to a user. Preferably, the filtrand releasing device comprises an interdigital transducer which generates surface acoustic waves for vibrating the filter. The vibration atomises deposited trapped particulate matter in the filter to generate an aerosol. The holder may have a first trapping mode (Fig. 6A) wherein smoke is drawn through the filter without passing to the mouthpiece, so as to capture filtrands in the filter; and a second puffing mode (Fig. 6B) wherein the filtrand release device operates on the filter to partially release the filtrands accumulated during the first mode into smoke supplied to the mouthpiece.

Description

Smoking device

Description

The present invention relates to smoking device which may be in the form of a cigarette holder or mouthpiece.

Battery-powered atomisers which generate an aerosol stream for inhalation are known in nicotine dehvery devices, such as the c-cigarette, which includes a nicotine-containing cartridge for delivering a nicotine containing aerosol. A disadvantage of this type of device is that it does not provide a similar experience to conventional tobacco burning cigarettes.

The c-cigarette looks, feels and tastes different to conventional cigarettes.

According to a first aspect of the invention there is provided a holder for a smoking article that in use produces smoke for a user and has a filter for filtering the smoke and capturing filtrands therefrom, the holder including: a receptacle for the smoking article, a mouthpiece, a passageway to supply a flow of smoke from a smoking article when received in the receptacle, after passing through the filter, to the mouthpiece, and a filtrand release device for operating on the filter to partially release the filtrands therefrom into the flow of smoke to the user.

In a preferred embodiment the holder is operable in a first, trapping mode wherein smoke from the smoking article is drawn through the filter without passing to the mouthpiece, so to capture filtrands in the filter, and in a second, puffing mode \vherein said filtrand release device operates on the filter to partially release the filtrands accumulated during the first mode into smoke supplied to the mouthpiece.

Preferably, the holder includes a backflow generating apparatus to draw air through the smoking article in the first mode.

io Optionally, the backfio\v generating apparatus is a fan. Alternatively, the backflow generating apparatus comprises a piston member caused to move under electromagnetic force.

In a preferred embodiment, the holder includes a valve arrangement operable (i) during the first mode to vent smoke passing through the filter to the outside \vithout passage to the mouthpiece, and operable @i) during the second mode to direct the smoke flow along the passageway to the mouthpiece.

Preferably, the filtrand release device comprises an interdigital transducer (IEDT) for generating surface acoustic waves (SA9. Optionally, the filtrand release device comprises an ultrasonic device for vibrating the filter.

In a preferred embodiment, the holder further comprises a visual indicator for displaying an indication of an error state to the user.

The holder, when inserted \vith a lit cigarette, can deliver a desired fraction of freshly trapped mainstream tobacco tar as an aerosol stream. In use, the battery-powered device works by automatically sensing and switching between two operation modes: a puff actuated delivery mode when the mouth piece is puffed, and a static tar trapping mode when the cigarette is left to smoulder.

Advantageously, this invention improves the sensory experience for the user because the perceived sensory experience of fresh smoke is generally superior to that of aged smoke or pharmaceutically mixed aerosol cartridges. By delivering a desired fraction of freshly generated mainstream tar which has been trapped, the device can be tailored to produce improved smoke taste than that of existing commercial heat-not-burn or electronic smoking articles.

In addition, the present invention may also reduce sidestream smoke. In a trapping mode, the cigarette holder can produce a small back flow of approximately I to 5 mL/min towards the mouth end of the device. This directs the smoke generated during the smoulder burn towards the cigarette filter, as opposed to being released as sidestream Jo smoke. The reduced fio\v also enhances the filter's trapping efficiency for smoke tar. The tar thus trapped on the cigarette filter forms the depository for the subsequent release of the aerosol to be inhaled by the smoker.

The holder may be used with conventional cigarettes of a suitable diameter.

The invention also includes in a second aspect a smokeable device that in use produces smoke for a user, including: a source of smokeable vapour; a filter for filtering the smokeable vapour and capturing filtrands therefrom; a mouthpiece, a passageway to supply the smokeable vapour to the mouthpiece, and a filtrand release device for operating on the filter to partially release the filtrands therefrom into the flow of smokeable vapour to the user.

The invention also includes a smoking method comprising: providing a source of smokeable vapour; filtering the smokeable vapour and capturing filtrands therefrom; supplying the smokeable vapour for use by a user; and partially releasing the filtrands from the filter into the flow of smokeable vapour to the user.

Embodiments of the present invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a perspective view of an aerosol atomiser in the form of a cigarette holder; Figure 2a is a side eleva don of the aerosol atomiser of Figure 1 showing a mouth end of the atonMser; Figure 2b is a side elevation of the aerosol atomiser of Figure 1 showing a cigarette receiving end of the atomiser; Figures 3a and 3b are front elevations of the aerosol atomiser of Figure 1 in two different modes; Figure 4a is a longitudinal cross-section of the aerosol atomiser without a cigarette in place; Figure 4b is a cross-section of the aerosol atomiser, similar to Figure 4a, with a cigarette in place; Figure 5a is a cross-section of the aerosol atomiser, through section C of Figure 1, showing an inlet opening cover in an open position; Jo Figure Sb is a is a cross-section of the aerosol atomiser, similar to Figure 3a, showing the inlet opening cover in a closed position; Figures 6a and 6b are longitudinal cross-sections of the aerosol atomiser showing more detail than Figure 4b; Figures 7a and 7b are partial cross-sections showing portions of Figures 6a and 6b in more detail; Figure Ba is a perspective view of an aerosol atomiser of one embodiment of the invention; Figure Sb is a front elevation of the aerosol atomiser of Figure Ba; Figure Sc is a cross-section of the aerosol atomiser, through section A-A' of Figure Sb; and Figure 9 is a circuit diagram of an electronic circuit for controlling the aerosol atomiser of Figure Ba.

Figure 1 shows an aerosol atomiser device I in the form of a cigarette holder and comprises a body section 2 and a mouth end section 4. The mouth end section 4 is shaped to be placed into a user's mouth.

The body section 2 and the mouth end section 4 form a casing for housing the components of the aerosol atomiser 1. The casing may be formed of an integral part, or may comptise a plurality of separate parts which are fastened or held together.

As shown in Figure 1, the mouth end section 4 tapers from a diameter similar to that of the body section 2 to a smaller diameter suitably sized for ease of retention in the user's mouth.

Figure 2a is a side elevation view of the atomiser 1, in the direction A shown in Figure 1. A mouth end rim 6 defines an opening S through which the user draws the generated aerosol.

A cigarette-receiving end 10 at the distal end of the atomiser device I from the mouth end 4, defines a cigarette-receiving opening 12 for receiving and retaining a conventional filter cigarette. Figure 2b is a side elevation of the atomiser 1, in the direction B. The cigarette-receiving opening 12 is defined by a front end rim 14 as shown in Figures 1 and 2b. Also shown in Figure 2b, at a distance within the body section, is a fan 16. An approximate io location for the fan is shown as a dashed line IS in Figure 1.

Also shown in Figure 1, are a plurality of openings 20, through witch air/vapour is drawn or dispersed. In the embodiment shown in Figure 1, there are two pairs of openings. A front-end pair 20a, referred to as upstream openings, are situated on the body section 2 at a location closer to the front end of the device, and a mouth-end pair 20b, rcferred to as downstream openings, are situated closer to the mouth-end 4.

As shown in Figure 3a, in a first operating mode the upstream openings 20a are open, and the downstream openings 20b are closed. Figure 3b shows a second operating mode in which the upstream openings 20a are closed, and the downstream openings 20b are open.

As shown in Figure 4a, the atomiser casing houses: a cigarette receiving portion 22, for receiving a filter end 24 of a cigarette 26; a flow-controlling mechanism 28, for controlling the flow of the generated aerosol; an electronic circuit 30 for controlling the flow-controlling mechanism 28, and a flow channel 32, for directing the generated aerosol toward the mouth-end 4 of the atomiser 1.

The cigarette receiving portion 22 consists of an opening at the front end, which is defined by the front end rim 14. Within the housing is a cavity 34, within which one or more receiving plates 36 are supported and appropriately biased such that the receiving plate(s) grip and retain a filter 24 of a conventional cigarette 26. As shown in Figure 4b, the filter 24 inserted in the cigarette receiving portion 22 pushes against the receiving plates 36 which are resihently biased to push toward the centre of the cavity. This biasing action grips and retains the cigarette 26 in place.

The cigarette receiving portion 22 comprises a cigarette sensor (not shown) which detects whether a cigarette has been inserted into the cigarette receiving portion. An electronic signal from the cigarette sensor is input into the electronic circuit 30.

In one embodiment, the receiving plate(s) 36 is coupled to a high frequency oscillator Jo which causes the receiving plate to vibrate as described in more detail below. The high frequency oscillator is electrically connected to the electronic circuit 30 and is controlled as appropriate. The high frequency oscillator in one embodiment is a piezoelectric device. A suitable oscillator is described in EPI 736065.

A person skilled in the art will appreciate other means which may be suitable for generating an aerosol. For example, an evaporation mechanism may use a heating device.

The flow-controlling mechanism 28, situated in an intermediate position between the cigarette receiving portion 22 and the flow channel 32, comprises the plurality of openings or ventilation holes as shown in Figures 1, 3a and 3b, and the fan 16 shown in Figure 2b and referenced with respect to Figure 1. The flow-controlling mechanism 28 also comprises an inlet opening 40 (also referred to as a central valve) between the cavity 34 of the cigarette receiving portion and the flow channel 32. The inlet opening 40 in one embodiment is situated behind the fan, toward the mouth end 4. An inlet opening cover 42 is operable to open or close the inlet opening.

One embodiment of the inlet opening 40 and inlet opening cover 42 is shown in Figures 5a and Sb, which are cross-sections through the body of the device at section C. As shown, the inlet opening cover 42 of this embodiment is formed from two sliding panels 42a, 42b.

However, other arrangements may be suitable.

The sliding panels 42a, 42b are supported on rails 44, and are forced apart when the inlet opening 40 is required to open, as shown in Figure Sa, and are caused to come together when the inlet opening 40 is closed, as shown in Figure Sb.

The flow-controlling mechanism 28 is shown in more detail in Figures 6a and 6b, which are longitudinal cross-sections through the body of the device. As shown, a supporting frame 48 is arranged to support the fan 14 and the inlet opening sliding panels 42a, 42b.

A plurality of ventilation sliding panels 50 which are arranged to slide in a longitudinal direction between a first position shown in Figure in 6a and a second position shown in Figure 6b.

Figure 7a and 7b show an example arrangement for the ventilation sliding panels corresponding to the encircled portions of Figure 6a and 6b, respectively. As shown, the ventilation panels may be linked together to permit airflow through the openings as desired. The arrangement shown comprises a first panel 50a and a second panel SOb and link 52.

The flow controlling mechanism 28 operates in two modes of operation. In a first mode, referred to as the trapping or smouldering mode, the flow-controlling mechanism 28 is arranged to trap mainstream smoke generated from a lit cigarette 26. This mode corresponds to the device shown in Figures 6a and 7a, where the second panel SOb is blocking the downstream opening(s) 20b, and the upstream openings 20a remain open, through the linked connection 52. In a second mode, referred to as an atomisation or puffing mode, the flow controlling mechanism 28 is arranged to permit flow of the trapped mainstream smoke to the flow channel 32 and to the user. This mode corresponds to the device shown in Figures 6h and 7b, where the first panel SOa is blocking the upstream opening(s) 20a, and the downstream openings 20b remain open, through the linked connection 52.

In the trapping/smoulder mode, as shown in Figure 6a, the fan 14 is switched on, the upstream openings 20a are open, the downstream openings 20b are closed, the inlet opening 40 is closed, and the high frequency oscillator is switched off. The upstream openings 20a provide ventilation to allow the escape of vapour phase smoke, represented by arrows X. The fan 14 introduces a low flow rate of approximately I to 5 niL/mm, which causes a backfiow of the smoke and leads to the entrapment of a significant proportion of the total particulate matter TPM) within the filter 24. The backflow draws the smoke into the filter, where it is trapped for a time to allow entrapment of the TPM, before being selectably released to generate the smoking aerosol, as explained below.

In the atomisation/puffing mode shown in Figure 6b, the fan 14 is switched off, the upstream openings are closed, the downstream openings 2Gb are open, the inlet opening 40 is open, and the high frequency oscillator is switched on. When the user draws on the device, a larger flow rate of 1L/min or more is drawn through the device, represented by arrow Y in Figure 6b. The generated aerosol is a combination of the aerosol provided from the filter and the inflow of air though the downstream openings 20b.

The high frequency oscillator causes the receiving plate(s) 36 to vibrate whtch in turn causes vibrations within the filter 24. This vibration generates an aerosol from the deposited trapped TPM in the filter. The energy and frequency of the atomiser is set as such that the species of TPM entering into the aerosol stream will he those of moderate molecular weights and volatiles. For example, this may include for example nicotine, humectants, and some tobacco smoke flavours of similar molecular properties and thermal stability.

In one embodiment, the atomiser 1 is arranged to cause re-evaporation of a selected fraction of freshly generated smoke tar. The re-evaporated fraction combines with air drawn through the downstream openings 20b to create the aerosol, while the remaining fraction is retained within the filter and not passed to the user.

Cigarette smoke tar contains a few thousand of high boiling point species, from semi-volatile to non-volatile. Tobacco specific nitrosamines (or TSNAs) and polycydic aromatic amines (PAHs) are two groups or examples of non-volatile toxicants featured in many reduction lists proposed by regulatory authorities, and so it is desirable to minimise the amount of these toxicants which pass into the generated aerosol.

The atomiser 1 is adjustable and can be tuned to release the selected fraction of the tar. For example, the frequency range and/or temperature of release can be controlled to affect the aerosol particle size (for the same substance) so that the generated aerosol is "tuned" to be absorbed differently.

In one embodiment, the device has an on/off switch to help preserve battery life when the device is not in use. To commence use, the user moves an on/off switch to the on position and inserts a cigarette 26 into the cigarette receiving portion 22. The cigarette may be pre-lit before insertion into the device.

io During use, the device is alternated between the two modes of operation. The trigger for switching from one mode to the other is generated from the electronic circuit as described below, and is at least partially controlled through detection of when the atomiser device is being puffed. In one embodiment, the detection of when the device is being puffed is achieved through detection, by a puff sensor 84 shown in Figure 9 (but not shown in Fig. 8) of a pressure change within the flow channel. Such detection of a pressure change is also known from EP1736065.

After use, the cigarette is removed and discarded in the usual way, and the device may he re-used with a new cigarette. The device can use disposable or rechargeable batteries 82 as shown in Figure 9.

As described above, the flow-controlling mechanism 28 controls the opening and closing of the upstream openings 20a, downstream openings 20b and the inlet opening 40 for the two operating modes.

One way in which these openings may be controlled is described in relation to Figures Ba to Be with respect to an alternative embodiment of the invention in which a pump coil arrangement is used to introduce the smoke backflow of 1 -5niL/rninute instead of the fan 14 described above.

As shown in Figure Ba, the device comprises the cigarette receiving portion 22', flow controlling mechanism 28', and flow channel 32' as before. Figure Bb, Bc, Bd and Be show the device in greater detail as comprising a forward flap valve 60, a pump coil 62 wound on a pump bobbin 64, a piston 65, a piston magnet 66 with a central aperture 67, and a piston stop 68 provided with through holes 69. The flow channel 32' includes ventilation air apertures 20b' In this embodiment, in the trapping mode, flow through the cigarette is achieved via cyclic movement of the piston 66. The piston 66 forms a seal 70 \vithin a tube 72 (e.g. a glass tube) and is able to move axially back and forth between the positions shown iii Figures Bc and Sd. The piston 66 includes radial apertures 73 that are closed when in the piston 66 is within the tube 72 as shown in Figures Bc and Bd but which open into the channel 32' Jo when the piston is in the position shown in Figure Be. The piston magnet 66 is attracted and repelled by the electromagnetic forces formed by a low frequency (LF) alternating current (AC) drive signal applied to the pump coil 62 by the LF amplifier. The desired flow -10 -rate of 1-Sml/minute is adjustable by adjusting the frequency and amplitude of the drive signal.

In the trapping mode, the piston 65 moving backward away from the cigarette i.e. from the position shown in Figure Sc to the position shown in Figure Sd, applies a flow drawing on the cigarette so as to deposit TPM in the filter 24.

The resulting smoke is caused to exit through the forward flap valve 60 during a subsequent forward stroke in which the piston 65 moves toward the cigarette i.e. from the postion shown in Figure Sd to that shown in Figure Sc. This action repeats on each cycle of the LF AC drive signal applied to the pump coil 62 until such time as the puff sensor is activated (i.e. a user draws on the device) , the cigarette sensor is deactivated (i.e. the cigarette is removed) or a predeterrriined timeout value has been reached. A predetermined timeout value may be reached if the cigarette has burned right down to the filter tip. If the timeout value has been reached or the cigarette sensor is deactivated the drive circuitry is disabled and enters a deep sleep mode.

When the puff sensor is activated (i.e. when the user draws on the device) a microcontroller shown in Figure 9, enters the puff mode. The microcontroller causes the piston 66 to be parked in a park position by applying a DC voltage to the pump coil 62, thereby causing the piston to move to the piston stop 68 as shown in Figure Se. A piston stop sensor 88 shown in Figure 9 (not shown in Fig. 8) detects the piston being moved into the park position. In one embodiment, the microcontroller 90 tests the state of the piston stop sensor, and if it is not activated the microcontroller generates an error signal which is displayed to the user through the flashing of and LED status indicator 92. Thereafter, the drive circuitry is disabled and the device enters a deep sleep mode.

When the piston is parked against the piston stop 68 and the user draws on the channel 32', the plurality of inlet openings 20b', admit a diluting air stream which can pass to the user through holes 69 in the piston stop 68.

In one embodiment, during the puff mode, a microcontroller drives an interdigital transducer (IDT) 100 shown in Figure 9 with a HF AC drive signal produced by oscillator -11 - 102 and amplifier 104. The IDT is physically coupled to the cigarette's filter 24 via a mechanism that wicks substances that have been trapped in the cigarette's filter during the trapping mode onto the surface of the IDT. The microcontroller 90 adjusts the drive signal to the optimum frequency and amplitude required for atomisation (using surface acoustic wave (SAW) action) of nicotine and other selected filtrant components. During the puff mode the atomised substances generate an inhalable aerosol stream which passes from the filter 24 through the central aperture 67 in the piston magnet and through the apertures 73 in the piston 65 as illustrated in Figure Se along with smoke drawn from the tobacco rod through the filter 24, and the resulting smokeable vapour passes through the holes 69 to the user along with ventilation air drawn through the holes 20b'.

When the puff sensor is deactivated the microcontroller 90 resets the pump by briefly energising the pump coil 62 with an alternating current (AC) dtive signal of specific amplitude and frequency. This action causes the piston magnet 66 to draw the pump's piston to the centre position of the pump coil 62. If the timeout value has been reached or the cigarette sensor is deactivated the microcontroller disables the drive circuitry and enters deep sleep mode.

An example of an electronic circuit 80 which may be used to control the flow-controlling mechanism 28' is shown in Figure 9.

The puff sensor 84, cigarette sensor 86 and piston stop sensor 88 described above are micro-switches which provide control inputs to a microcontroller 90. These inputs are termed Interrupt-on-Change-of-State inputs such that when changes in these inputs are detected a change in the control of the device can be achieved.

The puff sensor 84 is activated when the device is puffed by the user. The cigarette sensor 86 is activated when a cigarette is inserted into the opening 22' of the device, and the piston stop sensor 88 is activated when the piston is parked in the park position.

The status indicator 92 is provided as a light emitting diode (LED) and is used to provide indication of normal operation and errors. For example, if the microcontroller 90 detects that the DC supply voltage is below a threshold required for correct operation of the -12 -electronics the microcontroller signals an error by flashing the status indicator 92 several times. Thereafter the electronic circuitry is disabled and the device enters the deep sleep mode.

The pump coil is driven by a low frequency (LF) amplifier 96. The microcontroller 90 provides a square wave drive signal to the LF amplifier 96; this frequency is adjustable from DC to a few kH2. The drive signal's high frequency content is removed by a filter 98. The microcontroller varies the amplitude of the LF amplifier's output signal, which is used to drive the pump coil 62, by adjusting the gain control of the LF amplifier 96. The microcontroller can disable the LF amplifier to save po\ver.

The IDT 100 is driven by a high frequency (HF) oscillator 102 and amplifier 104. The microcontroller provides a square wave drive signal to the HF oscillator 102 which in turn produces a HF output signal adjustable around a nominal value (e.g. 48MHz), which is input to the HF amplifier 104. The HF amplifier's output signal is conditioned and matched to the impedance of the IDT by the filter and impedance matching circuit. The microcontroller varies the amplitude of the HF amplifier's output signal by adjusting the gain control of the HF amplifier. The microcontroller can disable the HF oscillator and HF amplifier to save power.

The above electronic circuit is included by way of example only, and does not represent specific limitations on the manner in \vhich the invention may be implemented. A person skilled in the art will appreciate many different ways in which a device operating in the different modes described above could be implemented without being limited to the

examples given.

Claims

-13 -Claims 1. A holder for a smoking article that in use produces smoke for a user and has a filter for filtering the smoke and capturing filtrands therefrom, the holder including: a receptacle for the smoking article, a mouthpi ccc, a passageway to supply a flow of smoke from a smoking article when received in the receptacle, after passing through the filter, to the mouthpiece, and a filtrand release device for operating on the filter to partially release the filtrands therefrom into the flow of smoke to the user.
2. A holder according to claim 1, operable in a first, trapping mode wherein smoke from the smoking article is drawn through the filter without passing to the mouthpiece, so to capture filtrands in the filter, and in a second, puffing mode wherein said filtrand release device operates on the filter to partially release the filtrands accumulated duting the first mode into smoke supphed to the mouthpiece.
3. A holder according to claim 2 including a backflow generating apparatus to draw air through the smoking article in the first mode.
4. A holder according to claim 3, \vherein the hackflow apparatus is a fan.
5. A holder according to claim 3, wherein the backflow apparatus comprises a piston member caused to move under electromagnetic force.
6. A holder according to any one of claims 2 to 5 including a valve arrangement operable during the first mode to vent smoke passing through the filter to the outside without passage to the mouthpiece, and operable during the second mode to direct the Jo smoke flow along the passageway to the mouthpiece. -14-
7. A holder according to any one of claims 2 to 5 including a puffing sensor operahle to detect puffing on the mouthpiece and to switch between said trapping and puffing modes.
8. A holder according to any preceding claim including a sensor to detect when a smoking article is received in the holder.
9. A holder according to any one of the preceding claims, wherein the filtrand release device comprises a device for vibrating the filter.
10. A holder according to any preceding claim wherein the filtrand release device comprises an interdigital transducer for generating surface acoustic waves.
11. A holder according to claim 9 or 10 wherein the frquency of vibration is selected to provide a predetermined release of fitrands from the filter.12. A holder according to any preceding claim further comprising a visual indicator for displaying an indication of an error state to the user.
12. A device that in use produces smokeable vapour for a user, including: a source of smokeable vapour a filter for filtering the smokeable vapour and capturing filtrands therefrom a mouthpiece, a passageway to supply the smokeable vapour to the mouthpiece, and a filtrand release device for operating on the filter to partially release the filtrands therefrom into the flow of smokeable vapour to the user.
13. A smoking method including: providing a source of smokeable vapour filtering the smokeable vapour and capturing filtrands therefrom supplying the smokeable vapour for use by a user, and partially releasing the filtrands from the filter into the flow of smokeable vapour to the user.
14. A holder or a smokeable device substantially as hereinbefore escribed with reference to the accompanying drawings.
15. A method of smoking substantially as hereinbefore described with reference to the accompanying drawings.