U.S. patent number 3,685,523 [Application Number 05/043,775] was granted by the patent office on 1972-08-22 for tobacco smoke filter.
This patent grant is currently assigned to Molins Machine Company Limited. Invention is credited to Francis A. M. Labbe.
United States Patent |
3,685,523 |
Labbe |
August 22, 1972 |
TOBACCO SMOKE FILTER
Abstract
A cigarette filter is provided with axially extending channels
divided by axially extending walls of filtering material through
which smoke is induced to pass from one channel to another,
different channels being blocked at different ends so that smoke
enters the filter by one channel and leaves by another. In the
preferred embodiment, the filter comprises a core having a
resistance to compression from which arms of filtering material
extend to the covering wrapper. These arm define smoke passageways
alternate ones of which are blocked at opposite ends so that the
smoke is constrained to pass from one channel or passageway through
a filtering arm to at least one of the adjacent channels.
Inventors: |
Labbe; Francis A. M.
(Neuilly-sur-Seine, FR) |
Assignee: |
Molins Machine Company Limited
(London, EN)
|
Family
ID: |
10341707 |
Appl.
No.: |
05/043,775 |
Filed: |
June 5, 1970 |
Foreign Application Priority Data
|
|
|
|
|
Jun 27, 1969 [GB] |
|
|
32635/69 |
|
Current U.S.
Class: |
131/339; 131/210;
131/340 |
Current CPC
Class: |
A24D
3/045 (20130101) |
Current International
Class: |
A24D
3/00 (20060101); A24D 3/04 (20060101); A24d
001/04 (); A24f 007/04 () |
Field of
Search: |
;131/10.3,10.5,10.7,10.9,210,211 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Rein; Melvin D.
Claims
What I claim as my invention and desire to secure by Letters Patent
is:
1. A cigarette filter comprising a tubular wrapper, a filter
element disposed within said wrapper, said filter element being
comprised of an axial core member from which a plurality of
radially directed arms extend so as to contact the wrapper, and
which define a plurality of smoke passage ways, alternate
passageways being blocked by smoke impervious means at opposite
ends, the arms being constituted of a filter material so that smoke
entering one passageway is constrained to pass through an adjacent
passageway before exiting after coursing through a filter arm, the
said core element being ineffective as a filter and having
resistance to compression higher than the filter.
2. A filter element according to claim 1, in which the filter
element is enclosed in a thermoplastic skin located within the
wrapper, the thermoplastic skin being deformed at localized spots
to form seals by which the ends of the passages are closed.
Description
The present invention relates to cigarette filters and more
particularly to those which have a non-axial smoke path through
them.
According to the present invention there is provided a cigarette
filter comprising a shaped filter element enclosed in a tubular
wrapper, and having at least two passages extending substantially
axially of the filter, at least one of said passages being formed
between the filter element and the inner surface of the wrapper,
different passages being blocked at different ends to allow smoke
to enter the filter by one passage and leave by another passage,
and being divided from each other by part of said filter element
through which smoke is constrained to pass.
How the invention may be carried out will now be described, by way
of example only, with reference to the accompanying drawings in
which:
FIG. 1 is a sectional view of one embodiment of the invention;
FIG. 2 is a first end view of the filter shown in Figure 1;
FIG. 3 is a second end view of the filter shown in Figure 1;
FIGS. 4 to 6 are views similar to FIGS. 1 to 3 respectively;
FIG. 7 is a sectional view of a third embodiment of the
invention;
FIG. 8 is a cross sectional view of a fourth embodiment of the
invention; and
FIG. 9 is a fragmentary sectional view in elevation of the
embodiment shown in FIG. 8.
FIGS. 1 to 6
A cigarette filter comprises a cylindrical filter element 26 which
has an axial channel 27 through it and which is wrapped in a thin
porous paper web 28. The element 26 may be formed from paper sheet
or tow already pre-loaded with finely divided filter material,
i.e., the paper or tow can be freely handled without any
significant loss of filtering material from it. The paper sheet or
tow may be formed around a stationary or spinning spindle so as to
form the axial channel 27.
The filter element is sealed at each end. At one end the central
axial passage 27 is sealed whereas at the other end the central
axial passage 27 is left open and a seal is formed around the outer
periphery of the element 26 to project radially outwardly from the
periphery in order to close the annular gap formed between the
element 26 and an outer wrapper 34. This may be done by locating
the filter plug in the flute of a rotating fluted drum, the plug
being held in the flute by suction. The sealing may be effected by
caps 29 and 30 of appropriate shape being stuck to the ends of the
plugs, as shown in FIGS. 1 to 3, or by the deposition of the
filling, such as hot melt adhesive, over the appropriate areas of
the ends of the plug to form seals 31 and 32 as shown in FIGS. 4 to
6.
The plug, with its ends carrying the seals referred to, is then
combined end-on with a porous plug such as that shown at 38 in FIG.
7, and held together by a strip of relatively stiff paper 34
wrapped and stuck around them.
The filter element 26 is relatively thick, i.e., its thickness is
equal to at least half the radius of the whole filter plug. Smoke
from a cigarette is drawn through the above mentioned porous plug
(not shown), such as 38 in FIG. 7, to cause smoke to enter the
axial channel 27 to the right of FIGS. 1 or 4 and then pass in a
generally radially outward direction through the filter element 26
and porous wrapper 28 into the annular channel between the element
26 and the outer wrapper 34. The seals 29, 30 and 31, 32 prevent
the smoke from passing through the ends of the cylindrical filter
element 26.
FIG. 7
In the embodiment shown in FIG. 7 the filter element 35 is again
cylindrical but comprises an homogenous substance which has equal
resistance to the passage of smoke in both an axial and a radial
direction. Because the material is homogeneous it is possible to
use an alternative sealing arrangement to the seals 29, 30 and 31,
32 of the embodiments of FIGS. 1 to 3 and 4 to 6 respectively.
With such a material its ends do not require to be sealed because
any excess pressure between one side of the material and the other
will result in a smoke flow through the thickness of the material,
provided that the central bore and the outer annulus are closed
over a length which is at least equal to the thickness of the
cylinder so that the shortest path length is through the wall of
the cylinder and not through its ends. Therefore, plugs 36, 37 are
provided whose lengths are greater than the thickness of the
cylinder 35. Thus, as the filter material is in the form of a
cylinder excess pressure applied between the inner bore and the
outside of the cylinder will cause smoke to pass through the
thickness of the cylinder and not through the ends of the
cylinder.
As in the previously described embodiments the filter element 35 is
combined with a porous plug 38 and the two are held together by a
substantially nonporous outer wrapper 39.
The way in which this filter plug may be manufactured will now be
briefly described. The cylinder 35 may be extruded from a suitable
filter material or it may comprise fiber which is highly loaded
with finely divided filter material so that the loss coefficient is
completely controlled by the finely divided filter material. These
filter lengths are then fed into the flutes of a rotatable drum and
held there by suction. As the drum rotates a non-porous plug 36 is
inserted into the central bore of one end of each cylinder and an
annular non-porous plug 37 is located around the other end of the
cylinder. The cylinder is then taken from the fluted drum and
brought end on with a filter stub 38, the two then being wrapped in
a tube 39 of relative thick paper so as to form an annular air gap
40 round the cylinder, the two being spaced from the outer
periphery of the cylinder by the annular plug 37.
FIGS. 8-9
In this embodiment the filter element is again made of a
homogeneous substance but instead of having a simple cylindrical
form in which smoke enters through the central bore, passes through
the walls of the cylinder and exits through the surrounding
annulus, or vice versa, the filter material is extruded in a
generally wheel-like cross section, i.e., a cross section
consisting of a hub or core having plurality of radially outwardly
extending arms so that, an equal number of channels are formed
between adjacent arms.
In particular, the extrusion shown in FIG. 8 has six arms 41 to 46
with six smoke passages 47 to 52 between adjacent pairs of arms.
With such a construction the channels 47, 49, and 51 would be open
at the tobacco end of the filter plug and sealed at the other end
whereas the channels 48, 50, and 52 would be open at the mouthpiece
end of the filter plug but closed at the tobacco end. Thus smoke
would enter the channels 47, 49, and 51, pass through the filter
arms 41 and 42, 43 and 44, and 45 and 46 respectively and leaves
the filter plug through the channels 48, 50, and 52.
With such a construction the smoke flow through the filter arms is
substantially by the shortest path, as indicated by the arrows, and
thus avoids the center zone of the extruded filter element. This
zone is thus ineffective as a filter and can with benefit be
replaced by a core 53 which has a relatively high resistance to
axial compression, as compared with the extruded filter material.
It is useful because in the production of such a filter the plugs
can be subjected to relatively high compressive forces in an axial
direction and if constructed entirely of the extruded filter
material would be liable to collapse axially. The central core 53
could be made of a relatively cheap material thus saving the cost
of the relatively expensive filter material which it replaces.
Various methods may be employed to effect the end sealing of the
channels 47 to 52 and in particular a 60.degree. triangular section
stub could be used in each channel. However, in the illustrated
embodiment (FIG. 9) this is effected by localized deformation by
heat sealing of a polythene skin 54 which encloses the cruciform
filter material. This is done prior to the cut-off of the
continuous filter rod at the lines A--A and B--B (FIG. 9). For a
filter plug length contained between the lines A--A and B--B the
tobacco end of the filter is adjacent the line A--A and the
mouthpiece and adjacent the line B--B.
* * * * *