Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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A CARTRIDGE FOR A VAPOUR GENERATING SYSTEM
Technical Field
The present disclosure relates generally to a cartridge for a vapour
generating system
configured to heat a liquid to generate a vapour which cools and condenses to
form an
aerosol for inhalation by a user of the system. The present disclosure also
relates to a
vapour generating system that comprises a vapour generating device and a
cartridge
configured to be used with the vapour generating device.
Technical Background
The term vapour generating system (or more commonly electronic cigarette or
e-cigarette) refers to handheld electronic apparatus that is intended to
simulate the
feeling or experience of smoking tobacco in a traditional cigarette.
Electronic
cigarettes work by heating a vapour generating liquid to generate a vapour
that cools
and condenses to form an aerosol which is then inhaled by the user.
Accordingly, using
e-cigarettes is also sometimes referred to as "vaping". The vapour generating
liquid
usually comprises nicotine, propylene glycol, glycerine and flavourings.
Typical e-cigarette vaporizing units, i.e. systems or sub-systems for
vaporizing the
vapour generating liquid, utilize a heating element to produce vapour from
liquid stored
in a capsule, tank or reservoir. When a user operates the e-cigarette, liquid
from the
reservoir is transported through a liquid transfer element, e.g. a cotton wick
or a porous
ceramic block, and is heated by the heating element to produce a vapour, which
cools
and condenses to form an aerosol that can be inhaled. To facilitate the ease
of use of
e-cigarettes, removable cartridges are often employed. These cartridges are
often
configured as "cartomizers", which means an integrated component comprising a
liquid
store, a liquid transfer element and a heater. Electrical connectors may also
be provided
to establish an electrical connection between the heating element and a power
source.
Such cartridges may be disposable, i.e. not intended to be capable of reuse
after the
supply of liquid in the reservoir has been exhausted. Altematively, they may
be
reusable, being provided with means allowing the reservoir to be refilled with
a new
supply of vapour generating liquid. Particularly in the case of disposable
cartridges, it
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is desirable to reduce the number and complexity of their components, thereby
reducing
waste and making the manufacturing process simpler and cheaper.
A cartridge for an e-cigarette typically comprises an air inlet at a first end
and an air
outlet at a second, opposite end. (Considered from the viewpoint of a user of
the
system, the first end of the cartridge may also be termed the distal end and
the second
end of the cartridge may also be termed the proximal end or mouth end.) The
first end
of the cartridge is configured to be releasably connected to the vapour
generating
device, which may, for example, contain a power source and control
electronics. A
to user
inhales through a mouthpiece at the second end of the cartridge to draw air
along
an airflow path from the air inlet to the air outlet. The airflow path passes
through a
vaporization chamber, where liquid vaporized by the heating element mixes with
the
air.
In order to allow time for the vapour to cool and condense into an aerosol
before it
reaches the second end of the cartridge, the vaporization chamber is typically
located
at the first end of the cartridge, close to the air inlet. The reservoir of
vapour generating
liquid may therefore be located towards the second end of the cartridge and be
separated
from the vaporization chamber by a generally transverse wall. (In this
specification,
"longitudinal- refers to the direction extending from the first end to the
second end of
the cartridge, parallel to the central axis of the cartridge if there is one,
and -transverse"
refers to any plane or direction that is generally perpendicular to the
longitudinal
direction.) The liquid transfer element allows liquid to pass from the
reservoir to the
vaporization chamber through the transverse wall. Therefore, if the liquid
transfer
element is in the form of a permeable sheet or block, it is typically set into
the transverse
wall with a similarly transverse orientation. In particular, the liquid
transfer element
presents a transverse surface in the vaporization chamber, on which heated
liquid is
exposed to the air in the chamber in order to vaporize and mix with the air in
the
chamber.
In many prior e-cigarettes, the air inlet is located centrally in the first
end of the
cartridge. (The location of the air inlet may be determined by the design of
the vapour
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generating device, to which the first end of the disposable cartridge is
connected.) The
vaporization chamber is also located centrally in the cartridge, close to the
first end,
whereby air entering the air inlet in the longitudinal direction flows
directly into the
vaporization chamber. This can give rise to two problems.
First, the direct airflow path from the air inlet to the vaporization chamber
provides a
direct channel for condensed liquid to leak out of the vaporization chamber in
the
opposite direction and emerge from the air inlet. Such leaked liquid may reach
the
exterior of the vapour generating system and be unsightly or otherwise
unacceptable to
the user. Additionally or alternatively, it may find its way into the vapour
generating
device and there cause damage to the power source or the control electronics.
Leakage
from the air outlet can also occur and is similarly undesirable.
The second problem is that, if the liquid transfer element presents a
transverse heated
surface in the vaporization chamber, as previously described, then air
entering the
chamber in the longitudinal direction impinges perpendicularly on that
surface. This
results in a concentrated airstream at one point on the surface, whereas it
would be
preferable to achieve vaporization of liquid into the air evenly across the
whole area of
the surface.
Summary of the invention
The invention provides a cartridge for a vapour generating system, the
cartridge
comprising a first end and a second end together defining a longitudinal
direction from
the first end to the second end; an air inlet; an inlet channel; a
vaporization chamber;
an outlet channel; and an air outlet; wherein an airflow path extends from the
air inlet
through the inlet channel to the vaporization chamber, then through the outlet
channel
to the air outlet; the cartridge further comprising restriction means for
restricting airflow
between the outlet channel and the air outlet.
The invention further provides a vapour generating system, which comprises
such a
cartridge releasably connected to a vapour generating device.
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The restriction means in the cartridge according to the invention offers one
or more of
the following advantages:
= If droplets of liquid have condensed on the walls of the outlet channel,
it helps
to prevent them flowing to the air outlet.
= It also serves to determine the pressure distribution along the airflow
path.
= It plays a significant role in determining the overall "resistance to
draw" of the
vapour generating system.
The restriction means is preferably a neck in the airflow path, a cross-
sectional area of
to the neck being smaller than a cross-sectional area of the outlet
channel. It is preferred
that the cross-sectional area of the neck should in fact be smaller than a
cross-sectional
area anywhere else along the airflow path. The reduced cross-sectional area of
the neck
offers resistance to the flow of air towards the air outlet. It is easy to
manufacture and
is less likely to become blocked than, for example, a restriction means formed
by a
mesh placed across the airflow path.
The neck is preferably oriented such that the airflow through it is in a
transverse
direction. This change of direction from the generally longitudinal outlet
channel offers
a further hindrance to drops of condensed liquid in the outlet channel that
might leak
from the air outlet.
The air outlet may be located in the second end of the cartridge. This is a
convenient
location for the air outlet to be used directly as a mouthpiece of the vapour
generating
system or to deliver air to a separate mouthpiece that may be located at the
second end
of the vapour generating system. An air outlet in the end of the cartridge
must have at
least a component of its airflow in the longitudinal direction. If the airflow
through the
neck is generally in the transverse direction, this provides a further change
of direction
and further hinders the passage of droplets of condensation that might leak
from the air
outlet.
Preferably the cartridge further comprises, between the restriction means and
the air
outlet, a lip that projects from the second end towards the first end. The lip
may be part
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of a collar that surrounds the air outlet. Such a lip or collar still further
hinders the
passage of droplets of condensation that might leak from the air outlet.
The cartridge typically further comprises a reservoir configured to store
vapour
generating liquid to be vaporized in the vaporization chamber. Preferably the
outlet
channel is disposed in the cartridge so that it does not intersect the
reservoir. For
example, the outlet channel may be disposed adjacent to a longitudinal side
wall of the
cartridge, rather than conventionally following a central axis of the
cartridge. This
avoids the need for a gasket, which would otherwise have to be provided to
seal around
to the outlet channel where it enters the reservoir.
Further preferred aspects of the invention relate to the inlet channel of the
cartridge,
which leads from the air inlet to the vaporization chamber.
The airflow path through the inlet channel preferably follows a first
transverse direction
then turns to enter the vaporization chamber in a second transverse direction.
Additionally or alternatively, the inlet channel is convoluted such that it
provides no
straight path from the air inlet to the vaporization chamber. For example, the
inlet
channel may comprise at least two right-angled bends between the air inlet and
the
vaporization chamber. Each of these features entails changes in direction
along the
length of the inlet channel, whereby, if droplets of condensed or unvaporized
vapour
generating liquid have collected in the vaporization chamber, those droplets
are
hindered from flowing towards and leaking out of the air inlet, at least as
long as the
vapour generating system remains held in a generally constant orientation.
An airflow diverter element may be disposed in the inlet channel, whereby a
first
surface of the diverter element defines the first transverse direction and a
second,
opposite surface of the diverter element defines the second transverse
direction. The
first transverse direction may thus be opposite to the second transverse
direction.
Preferably, the airflow path through the air inlet is substantially parallel
to the
longitudinal direction. This ensures that there is a further change of airflow
direction
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between the air inlet and the first transverse part of the inlet channel. It
allows the air
inlet to be conveniently located centrally in the first end of the cartridge.
A cartridge according to the invention may further comprises a heater surface
in the
vaporization chamber that is substantially transverse to the longitudinal
direction.
Preferably the airflow path through the vaporization chamber is substantially
parallel
to the heater surface to encourage substantially uniform evaporation of the
vapour
generating liquid from all parts of the surface.
to The heater surface may be a distal surface of a ceramic heating element
and may
comprise a heating track that extends between two electrical connection
points. In
preferred embodiments of the invention, the cartridge further comprises two
electrical
terminals that are exposed to the exterior of the cartridge and respectively
contact the
two electrical connection points. Thereby, the use of loose wires is avoided
and the
manufacturing process becomes simpler and more reliable.
The cartridge is intended for use in a vapour generating system configured to
heat a
vapour generating liquid within the cartridge to volatise at least one
component of the
vapour generating liquid and thereby generate a vapour which cools and
condenses to
form an aerosol for inhalation by a user of the vapour generating system.
The vapour generating liquid may, for example, comprise polyhydric alcohols
and
mixtures thereof such as glycerine or propylene glycol. The vapour generating
liquid
may contain nicotine.
In general terms, a vapour is a substance in the gas phase at a temperature
lower than
its critical temperature, which means that the vapour can be condensed to a
liquid by
increasing its pressure without reducing the temperature, whereas an aerosol
is a
suspension of fine solid particles or liquid droplets, in air or another gas.
It should,
however, be noted that the terms 'aerosol' and 'vapour' may be used
interchangeably
in this specification, particularly with regard to the form of the inhalable
medium that
is generated for inhalation by a user.
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Description of the drawings
Figure 1 is a longitudinal section through a cartridge according to an
embodiment of
the present invention.
Figure 2 is an exploded perspective view of the cartridge of Figure 1.
Figure 3 is a schematic diagram of a vapour generating system that comprises a
cartridge in accordance with the present invention.
The cartridge 2 illustrated in the drawings has a generally rectangular shape,
with a
longitudinal axis 4 extending between a first end 6 and a second end 8 of the
cartridge 2. As seen in this embodiment, the cartridge 2 need not be
symmetrical about
the axis 4. The first end 6 of the cartridge 2 is provided with connection
means 10 for
clipping or otherwise releasably connecting the cartridge 2 to the vapour
generating
device 11 which may, for example, contain a power source 50 and control
electronics 52.
The second end 8 of the cartridge is substantially occupied by a reservoir 20,
which
stores a vapour generating liquid. In the centre of the first end 6 of the
cartridge 2, there
is formed an air inlet 12. It may be assumed that when the cartridge 2 is
connected to
the vapour generating device 11, air is still able to flow from the
surrounding
atmosphere to the air inlet 12, for example through one or more air passages
(not
shown) formed in the vapour generating device 11. The air inlet 12
communicates with
an inlet channel 14, which leads to a vaporization chamber 22 (described
below). In or
near the centre of the second end 8 of the cartridge, there is formed an air
outlet 16. An
outlet channel 17 leads from the vaporization chamber 22 to the air outlet 16.
Because
the vaporization chamber 22 is located near the first end 6, the outlet
channel 17
conducts air over the majority of the length of the cartridge 2 from the first
end 6 to the
second end 8. The outlet channel 17 is offset laterally from the axis 4 to
follow one of
the longitudinal side walls 18 of the cartridge housing 15 and pass to one
side of the
reservoir 20.
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A separate mouthpiece 19 (seen in Figure 3) can be releasably connected to the
second
end 8 of the cartridge. In some embodiments, the second end 8 of the cartridge
2 itself
can act as a mouthpiece, in the sense that a user can engage their lips
directly with the
second end 8 of the cartridge 2. The mouthpiece 19 is in fluid communication
with the
air outlet 16 so that, by sucking on the mouthpiece 19, a user of the vapour
generating
system can draw air through the cartridge 2. The air follows a continuous
airflow path
extending from the air inlet 12 at the first end 6, successively through the
inlet
channel 14, the vaporization chamber 22 and the outlet channel 17, to the air
outlet 16
and the optional mouthpiece 19 at the second end 8.
A gasket 24 rests on a seat 21 within the cartridge housing 15 and separates
the
reservoir 20 at the second end 8 of the cartridge 2 from the vaporization
chamber 22 at
the first end 6. The gasket 24 is applied during manufacture to close the
reservoir 20
after it has been filled with vapour generating liquid. If the reservoir 20 is
designed to
be refillable, then the gasket 24 must be capable of removal to admit a new
supply of
liquid into the reservoir 20. The gasket 24 engages the inner wall of the
reservoir 20 to
form a seal that prevents leakage of the vapour generating liquid from the
reservoir 20.
Because the outlet channel 17 is offset laterally and does not pass through
the
reservoir 20, it is not necessary to provide a second gasket to seal around
the
channel 17. The illustrated embodiment of the invention therefore enables a
reduced
number of components and a simpler manufacturing process compared with the
prior
art.
A ceramic block 26 is set into the gasket 24 such that its distal surface 28
is transversely
aligned and is exposed to the vaporization chamber 22. An opposite, proximal
surface 29 of the ceramic block 26 is exposed to the liquid in the reservoir
20. The
ceramic block 26 is porous and acts as a liquid transfer element to transport
liquid, as
indicated by arrow 31, from the reservoir 20 to the distal surface 28, where
the liquid
is exposed to the vaporization chamber 22.
An electrically conductive heating track 30 is printed on the distal surface
28 of the
ceramic block 26, which therefore may also be termed a heater surface. The
heating
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track 30 extends between a pair of electrical connection points 32. The
respective
electrical connection points 32 are contacted by the proximal ends of a pair
of electrical
terminals 34. The distal ends of the electrical terminals 34 are exposed to
the exterior
of the cartridge 2. Specifically, they are exposed on the first (distal) end 6
of the
cartridge 2 to provide an electrical connection from the heating track 30 to a
power
source 50 contained within the vapour generating device 11. When a voltage is
applied
between the electrical terminals 34, current flows through the heating track
30 and
resistive heating raises the temperature of the heater surface 28 of the
ceramic block,
thereby causing liquid to vaporize from the surface 28 into the airstream that
passes
through the vaporization chamber 22. An airflow sensor (not illustrated) may
be used
to detect when air is moving along the airflow path, whereby a control circuit
52 in the
vapour generating device 11 can conserve energy by supplying power to the
heating
track 28 only when a user is inhaling though the system. The airflow sensor
may be
located in the vapour generating device 11 to detect when air is moving along
an air
passage that leads to the air inlet 12. The electrical terminals 34 are
preferably
constructed as rigid elements that can be brought into contact with the
electrical
connection points 32 of the heating track 30 during assembly of the system.
Thereby,
the use of loose wires is avoided and the manufacturing process becomes
simpler and
more reliable. The electrical terminals 34 may be embedded in an end cap 36 of
the
cartridge 2. An end cap gasket 37 forms an airtight seal between the end cap
36 and
the cartridge housing 15 to ensure that air cannot enter the cartridge 2
except by
following the intended airflow path from the air inlet 12.
Because the air inlet 12 is aligned with the axis 4, air is drawn into the air
inlet 12 in
the longitudinal direction. In this embodiment the vaporization chamber 22
also lies on
the axis 4 so, if the air from the inlet 12 were permitted to continue in a
straight path, it
would enter directly into the vaporization chamber 22 in the longitudinal
direction.
However, the air that flows from the inlet 12 is forced instead to follow a
convoluted
path through the inlet channel 14, which results in it entering the
vaporization
chamber 22 along the transverse direction, parallel to the heater surface 28.
Specifically, a diverter element 38 extends transversely between the air inlet
12 and the
vaporization chamber 22 to divert the airflow away from its longitudinal
direction at
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the air inlet 12. Other methods of forcing the air to follow a convoluted path
will be
readily apparent, including forming the diverter element 38 integrally with
the end
cap 36 or with the main body of the cartridge 2.
The airflow diverted from the air inlet 12 is indicated by arrows 40. It
initially travels
in a first transverse direction (to the right as viewed in Figure 1),
following a distal
surface of the diverter element 38 and (in this embodiment) passing around one
of the
electrical terminals 34. After reaching the extremity of the diverter element
38, the
airflow reverses and follows a proximal surface of the diverter element 38,
travelling
in a second transverse direction (to the left as viewed in Figure 1) that is
opposite to the
first transverse direction. The airflow again passes around one of the
electrical
terminals 34 to enter the vaporization chamber 22 in the second transverse
direction.
Because the airflow through the vaporization chamber 22 is parallel to the
heater
surface 28, it affects all parts of the heater surface 28 equally and gives
rise to
substantially even vaporization of liquid across the whole area of the surface
28. The
airflow preferably exits from the vaporization chamber 22 opposite to its
entry point,
then follows the outlet channel 17 towards the second end 8 of the cartridge
2. During
the passage of the air along the outlet channel 17, there is time for it to
cool and for the
liquid vapour it carries to condense into droplets before the resulting
aerosol is inhaled
by the user.
Liquid can sometimes collect in the vaporization chamber 22, either because
liquid
presented on the heater surface 28 fails to vaporize fully or because liquid
that has
vaporized subsequently re-condenses on the internal walls further along the
airflow path
and flows back to the vaporization chamber 22. It is desirable to prevent the
collected
liquid leaking out of the cartridge 2. Preferably, the inlet channel 14 should
be
sufficiently convoluted that there exists no straight path from the air inlet
12 to the
vaporization chamber 22, along which liquid from the vaporization chamber 22
might
easily leak out of the air inlet 12. This can be achieved by forming the inlet
channel 14
with a single bend, provided the values of the angle of the bend, the length
of path on
each side of the bend, and the width of the channel 14 combine to exclude such
a
straight path. However, it is preferred that, as illustrated, the inlet
channel 14 is formed
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with at least two 90 bends. The inlet channel 14 can include one or more
segments
that lie outside the plane of Figure 1. The inlet channel 14 might further
include one or
more segments that are curved ¨ for example, helical ¨ especially if the
cartridge were
to have a cylindrical form instead of the rectangular box of the illustrated
embodiment.
As previously described, the outlet channel 17 extends in the longitudinal
direction
along one side wall 18 from the vaporization chamber 22 to the second end 8 of
the
cartridge 2. At the end of the side wall 18, the air flow path turns through
90 so that
air flows in the transverse direction towards the air outlet 16 located near
the centre of
the second end 8. Between the outlet channel 17 and the air outlet 16, the
airflow path
passes through means 42 for restricting the airflow. The restriction means 42
may
comprise one or more baffles or a mesh that offers resistance to the flow of
air
therethrough. However, as shown in the illustrated embodiment, the restriction
means
is preferably a portion of the airflow path that is constricted to form a
narrow neck 42.
The cross-sectional area of the neck 42 is smaller than the cross-sectional
area of the
outlet channel 17 and is preferably smaller than the cross-sectional area of
the airflow
path anywhere else along its length. The cross-sectional shape of the neck and
its length
when measured along the airflow path will both have some effect on the
resistance that
the neck offers to the flow of air but the cross-sectional area is the most
important factor.
If droplets of liquid have condensed on the walls of the outlet channel 17,
the restriction
means 42 helps to prevent them flowing to the air outlet 16, where they could
leak from
the cartridge 2 and enter the mouth of the user or cause drips from the
exterior of the
cartridge 2. A further feature that helps to prevent droplets of liquid
leaking from the
air outlet 16 is an internal lip 44 that projects back from the second end 8
towards the
first end 6 of the cartridge between the neck 42 and the air outlet 16.
Thereby, if the
cartridge 2 is oriented such that liquid droplets are flowing towards the
second end 8,
those droplets cannot reach the air outlet 16 without first changing direction
to flow
back towards the first end 6. Preferably the lip 44 surrounds the air outlet
16. For ease
of manufacture, the air outlet 16, the lip 44 and part of the neck 42 may be
formed on a
second end cap 46 that is fitted into the second end 8 of the cartridge 2
during the
manufacturing process. Inserting the second end cap 46 provides an easy way to
control
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the depth of the airflow path (measured in the longitudinal direction) at the
neck 42 and
hence, for any given width of the airflow path (measured perpendicular to the
plane of
Figure 1), to control the cross-sectional area of the neck 42.
The neck 42 is preferably formed such that the airflow through it is in the
transverse
direction. However, the neck 42 may alternatively or additionally be formed
adjacent
to the lip 44, where the airflow has at least a component of movement in the
reverse
longitudinal direction, back towards the first end 6 of the cartridge 2, in
order to pass
over the lip 44.
Being the most constricted part of the airflow path, the neck or other
restriction
means 42 also serves to determine the pressure distribution along the airflow
path.
When the user draws on the mouthpiece 19, it creates low pressure at the air
outlet 16,
while the air inlet 12 remains substantially at atmospheric pressure. This
difference in
pressure is distributed along the length of the airflow path, the pressure
distribution
depending on the resistance to the flow of air at each point. Because the neck
42 offers
the greatest resistance to airflow, it defines the region of greatest pressure
drop.
Providing a neck 42 of appropriate cross-sectional area at the second end 8 of
the
cartridge is a convenient way to determine the desired pressure within the
vaporization
chamber 22 and along the outlet channel 17, which helps to regulate the
formation of
the aerosol in the vapour generating system. The neck or other restriction
means 42
also plays a significant role in determining the overall "resistance to draw"
of the
vapour generating system, which is an important factor when designing such a
system.
Figure 3 schematically shows one possible configuration of a vapour generating
system
in accordance with the present invention. A vapour generating device 11 houses
a
power source 50, which provides power to a control circuit 52. The distal end
6 of a
cartridge 2 is releasably connected to the vapour generating device 11. There
is a
mouthpiece 19 at the proximal end 8 of the cartridge 2, which may be attached
to or
integral with the cartridge 2. Terminals 34 couple the power source 50, via
the control
circuit 52, to a heater 30 in the cartridge 2. Although the cartridge 2 and
vapour
generating device 11 are shown connected in an end-to-end configuration, it
will be
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understood that in alternative embodiments of the invention the cartridge 2
could be
releasably inserted inside the housing of the vapour generating device 11. In
that case,
the mouthpiece 19 could be attached to or integral with the vapour generating
device 11
rather than the cartridge 2.
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