Note: Descriptions are shown in the official language in which they were submitted.
CA 02263002 1999-02-08
WO9X/0~401 PCT/GB97/02120
A WA~ER TREATM~T CARTRI~GE AND A ~AT~R
FI~TER JUG FITTED WITH SVCH A CARTRID~
This invention relates to a water treatment cartridge
for use in a domestic water treatment apparatus,
particularly a water filter jug.
Water filter jugs generally comprise a receptacle and
a removable hopper, which hopper can be supported in or on
the receptacle. The hopper is adapted to carry a water
filter cartridge which typically comprises a moulded
container having inlet and outlet slots formed therein to
allow water to enter and exit an internal cavity. The
cartridge contains water treatment medium in the cavity,
which medium comprises a particulate filter and typically
also includes granules of an adsorbent material such as
activated carbon. The particles of the water treatment
medium typically have diameters of the order of 200~m or
more. In use, the cartridge is located in the hopper so
that the inlet s~ots open into the hopper and the outlet
slots open into the receptacle. When unfiltered water is
poured into the hopper it flows through the inlet slots of
the cartridge into the container and through the water
treatment medium, where it is purified. The water then
debouches the cartridge into the receptacle through the
outlet slots. The cartridge and medium are designed to
provide that the dwell time of water in the cartridge is
such as to provide adequate purification.
A problem with such cartridges is that particles of
the water treatment medium itself, for example blac~
CA 02263002 1999-02-08
WO9810~401 PCT/GB97102120
carbon, can escape from the cartridge through the outlet
slots. Whilst these particles are not harmful, their
presence in the receptacle is undesirable as they are
visible in the filtered water which may lead users of the
jug to the mistaken belief that the filtered water is
dirty. Also, as a result of turbulent back flow when water
is poured into the hopper, particles of the filter medium
can be back washed through the inlet slots, so that they
gather and are visible in the hopper. Again this is
undesirable as the hopper appears to be dirty. However, as
a result of the fact that the containers with the slots are
formed using plastics moulding techniques, which in
practical terms limits the width of the slots to about
250~m, it is not practicable to make such slots narrow
enough to prevent the particles escaping from the
cartridge.
An object of the present invention is to provide a
water filter cartridge in which particles of the water
treatment medium are substantially prevented from escaping
therefrom.
According to one aspect of this invention there is
provided a water treatment cartridge according to claim 1.
The water treatment medium will usually comprise
filtration granules or beads, and may optionally further
2S comprise a particulate adsorber.
Preferred forms of reticulated screen are claimed in
claims 2 to 7. The manner ~y which the cartridge is
.. ..
CA 02263002 1999-02-08
W O 98/05401 PCT/GB97/02120
provided with a mesh may be as claimed in any one of claims
8 to 10.
The container may be a two-part casing comprising a
substantially cup-shaped receptacle and a closure as
claimed in claim 11, so that the receptacle can be filled
with the particulate water treatment medium and the closure
fitted subsequently thereonto. A preferred form of the
invention is claimed in claims 12 and 13. The closure may
be snap-fitted onto the receptacle, as claimed in claim 14
or claim 15 so that manufacture of the cartridge is
facilitated.
The mesh may have an interstice size in the range
SO~m-300~m, preferably 80~m -200~m.
A handle portion may be provided. The handle portion
may have finger grips thereon.
According to another aspect of this invention there is
provided a water treatment cartridge according to claim 17.
According to a further aspect of this invention there
is provided a water treatment apparatus, particularly a
water filter jug comprising a water treatment cartridge in
accordance with this invention.
Water filter cartridges in which the present invention
is embodied will now be described by way of example only,
and with reference to the following drawings, in which:-
Figure 1 is a side elevation, partly in section, of a
water filter jug;
Figure 2 shows a sectioned fragment of a water filter
cartridge;
CA 02263002 1999-02-08
W O 98/0~401 PCTIGB97102120
Figure 3 is a plan view of a closure of the cartridge
shown in Figure 2;
Figure 4 shows a part section on the line IV-IV of
Figure 3;
Figure 5 shows a part section on the line V-V of
Figure 4;
Figure 6 is a front elevation of a container of the
cartridge shown in Figure 2;
Figure 7 is a perspective view of a filter insert of
the cartridge shown in Figure 2;
Figure 8 is a plan view of another water filter
cartridge;
Figure 9 is a side elevation of the cartridge shown in
Figure 8;
Figure 10 is a sectioned fragment of the water filter
cartridge shown in Figures 8 and 9, the section being on
the line X-X in Figure 9;
Figure 11 is a fragmentary section showing a
modification of the water filter cartridge shown in Figures
8 to 10; and
Figure 12 is a section on the line XII-XII in Figure
11 .
Figure 1 shows a water filter jug which has a jug
portion 1 and an removable internal hopper 2 which together
define an upper and a lower compartment 3 and 4
respectively. The hopper 2 carries a water filter cartridge
5, so that when in use unfiltered water is poured into the
upper compartment 3, and flows therefrom through the
~ .. ~ .. . .. . .... .. ... . . .. ... . .. . .... ..
CA 02263002 1999-02-08
W O 98/05401 PCT/GB97102120
cartridge 5, where it is filtered and purified, and into
the lower compartment 4. This kind of jug is well known and
need not be described further.
Figure 2 shows one form of water filter cartridge 6
for use as the water filter cartridge 5. The cartridge 6
has three parts; namely a generally cylindrical receptacle
7, a filter insert 9 and a closure ll.
As shown in Figures 3 an~ 4, the closure 11 comprises
a crown portion 19 and a s~irt portion 21. Integrally
moulded with the crown is a hollow cylindrical handle 13 on
opposing sides of which are formed finger holds lS. The
finger holds 15 are provided so that when the cartridge 6
has been used and is to be removed from the hopper 2, the
handle 13 can be readily grasped so that the cartridge 6
can be easily removed.
Four internal ribs 23 are provided at
circumferentially spaced locations around the interior of
the closure 11, each in the corner between the crown
portion 19 and the skirt portion 21. A plurality of
internal protrusions 26 are provided at circumferentially
spaced locations around the rim of the skirt portion 21.
The protrusions 26 are adapted to provide a tamper-proof
snap-fit onto an external ridge 27 which is formed so as to
extend circumferentially around the upper extremity of a
nec~ portion 29 of the receptacle 7 (see Figure 6). To this
end, each protrusion 26 has a chamfer formed in the
radially inner edge of its face that is further from the
crown portion 19. Also each protrusion 26 extends radially
CA 02263002 1999-02-08
WO9810~401 PCTIGB97/02120
inwardly from the skirt portion 21 by an amount which is a
little greater than the amount by which the ridge 27
projects radially outwardly from the neck portion 29.
The neck portion 2g further comprises an integrally
formed sleeve 35 which cooperates with a flange (not shown)
in the hopper 2 to locate the cartridge 6 in the hopper 2
in use and form a substantially water tight seal between
the hopper 2 and the cartridge 6.
Figure 2 shows the filter insert 9 is fitted in the
neck portion 29. Figure 7 shows it comprises two concentric
rings 39 and 40 which are spaced apart by four posts 41.
The ring 39 has a spider 43 which supports a mesh 45. The
other ring 40 has a slightly larger outer diameter than the
ring 39. The insert 9 is fitted into the neck portion 29 so
that the ring 40 abuts the top of the ridge 27 and the
lower ring 39 is within the neck portion 29.
The remainder of the receptacle 7 comprises a
cylindrical sidewall 33 which depends from the neck portion
29, and a bottom wall 34 in which an opening 36 is formed.
The opening 36 is covered by a mesh 37. This mesh covered
opening 36 serves in use as a water outlet. Openings are
also formed in the neck portion 29 itself and in the
closure 11, the openings in the neck portion 29 being in
the form of slots 31 and the openings in the closure 11
being slots 17 and 18 formed in the handle 13 and slots 25
formed in the skirt portion 21, see Figures 3 to 5. The
slots 31,17,18 and 25 and the mesh 45 of the insert g serve
in use as a water inlet to the cartridge 6. The slots
CA 02263002 1999-02-08
W O 98/0~401 PCT/GB97102120
3~,17,18 and 25 also provide an escape route for air which
is forced out of the cartridge 6 when water is poured
therethrough.
The receptacle 7 contains a particulate water
S treatment medium 10 which usually comprises filtration
granules or beads, and sometimes further comprises a
particulate adsorber. The diameter of the particles is
typically 200~m or more.
The mesh size of the mesh 37 and 45 is sufficient to
allow water to flow therethrough whilst at the same time
being smaller than the particles of the water treatment
medium 10 so that those particles cannot escape the
cartridge 6 therethrough. Usually an interstitial diameter
of about SO~m-300~m is selected, preferably BO~m-200~m. The
insert 9 and the receptacle 7 are manufactured so as to
provide as small as possible a clearance therebetween, so
that particles cannot escape therethrough.
To assemble the cartridge 6, the receptacle 7 is
filled with water filter medium 10 to just below the level
of the slots 31. The insert 9 is then press-fitted into
place so that there is woven mesh 45 between the slots 31
and the filter medium 10. The closure 11 is then
snap-fitted onto the receptacle 7, and the insert 9 is held
in place by the internal ribs 23 with the radially
outwardly projecting portion of the ring 40 trapped between
the ribs 23 and the top of the neck portion 29 in a water-
tight abutment with the top of the neck portion 29. A~ the
closure 11 is snap-fitted onto the receptacle 11, the skirt
CA 02263002 1999-02-08
W O 98105401 PCT/GB97102120
portion 21 is initially deflected radially outwardly, first
by the wedging interaction of the chamfers formed by the
outer periphery of the ring 40 and the inner edge of the
projections 26 and then by the ridge 27 as the projections
26 are forced over it. Once the projections 29 have been
forced passed the ridge 27, they snap back into abutment
with the outer surface of the neck portion 29 below the
ridge 27 due to the resilience of the skirt portion 21.
In use, the cartridge 6 is fitted to the water filter
jug so that communication between the upper compartment 3
and the interior of the cartridge is enabled by the inlet
which comprises the slots 17, lB, 25 and 31 and the mesh
45, and communication between the interior of the cartridge
and the lower compartment 4 is enabled by the outlet which
comprises the mesh 37. Hence, when unfiltered water is
poured into the upper compartment 3, water flows through
the slots 17, 18, 25, and 31, through the mesh 45 of the
insert 9 and then into the filter medium 10. In the event
of turbulent backflow of water within the receptacle 7 as
water is being poured into the upper compartment 3, the
abutment between the lower ring 39 and the inner surface of
the nec~ portion 2g ensures that the water can only move
upwards into the upper compartment 3 through the mesh 45
and thereby prevents particles of the water filter medium
10 moving thereinto. Once the water has filtered through
the water filter medium 10 it then leaves the cartridge
through the mesh 37 at the base. The presence of the mesh
CA 02263002 1999-02-08
W O 98/05401 PCT/GB97/02120
37 prevents particles of the water filter medium 10
entering the lower compartment 4.
The insert 9 including the mesh 45 is formed as a
one-piece molding so that the mesh 45 and the structure of
- 5 the insert 9 by which it is supported is formed as an
integral construction. Likewise the receptacle 7 and its
mesh 36 is also formed as a one-piece molding so that the
mesh 36 and the structure by which it is supported is
formed as an integral construction.
Figures 8 to 10 show another water filter cartridge in
which the present invention is embodied which has a closure
47 and a receptacle 49. The closure 47 has a circular crown
portion 48 which is domed and from which depends a skirt
portion 50, which skirt portion 50 is adapted to be fitted
onto a neck portion 55 of the receptacle 49.
As with the previously described receptacle 7, a
cylindrical sidewall depends from the neck portion S5 and
there is a bottom wall at the lower end of that sidewall.
The cartridge is provided with a plurality of openings
which serve in use as a water inlet. These openings
include four mesh covered arcuate slots 53 which are formed
in the crown portion 48 of the closure ll. In addition, the
water inlet comprises a plurality of mesh covered apertures
57 formed at circumferentially spaced locations around the
neck portion 55 of the receptacle 49. The mesh which covers
the apertures 57 is moulded into the neck portion 55. The
area of each of the apertures 57 is sufficiently large for
there to be a negligible resistance to flow of water
CA 02263002 l999-02-08
W O 98/05401 PCT/GB97/02120
throuyh them. Even though each of these apertures 57 is
covered with mesh, the resistance to flow of water
therethrough is less than would arise if the narrowest of
slots that, in practice, can be formed by plastic molding
techniques, were to be provided in place of these mesh
covered apertures 57. The skirt portion 50 extends around
the neck portion 55 and thereby substantially conceals the
relatively unsightly mesh covered apertures 57 from view.
It is provided with a plurality of circumferentially spaced
elongate slots 51 which allow a substantially unrestricted
flow of water to the mesh covered apertures 57.
As with the previously described receptacle 7, an
opening 36 is formed in the bottom wall of the receptacle
49. This opening 36 is covered by an integrally molded mesh
37 and serves in use as a water outlet.
To assemble the cartridge the receptacle 49 is filled
with water treatment medium and the closure 47 is then
placed over the neck portion 55. The closure 47 is then
welded, for example by sonic welding, to the upper end of
the neck portion 55.
When unfiltered water is poured into the upper
compartment 3 of a water filter ~ug using a water filter
cartridge of this type, water flows into the cartridge
through the mesh which covers the arcuate slots 53, and
also through the elongate slots 51 and the mesh which
covers the apertures 57. In the event of a turbulent
backflow of water within the receptacle 49, the fact that
the closure 47 is sealed to the receptacle 49 ensures that
CA 02263002 1999-02-08
WO98/05401 pcTlGs97lo2l2o
11
the water can only enter the upper compartment 3 through
mesh and thereby prevents particles of the water treatment
medium 10 moving upwards thereinto. Once the water has
filtered through the water treatment medium 10 it then
leaves the cartridge through the mesh 37 at the base, which
prevents particles of the water treatment medium 10
entering the lower compartment 4.
Air displaced from the water treatment medium in the
receptacle 49 by the passage of water therethrough will
rise up into the interior of the closure 47 formed by the
domed crown portion 48. Such airflow is unimpeded by the
mesh that covers the apertures 57. Should that air collect
and form any air bubble in the interior of the closure 47,
that bubble will be above the mesh covered apertures 47 and
thus will not impede ingress of water through those
apertures 57.
It will be understood that whilst in the cartridge
described with reference to Figures 8 to 10, the apertures
57 are covered by mesh which is moulded into the neck
portion 55, it is possible to overlay the apertures 57 with
an insert comprising a generally cylindrical or
frusto-conical mesh wall supported by a suitable
integrally-molded frame. Such an insert will be adapted to
be received in the neck portion 55. In this example, the
insert and the neck portion 55 are such that when water
flows through the apertures 57 it can only enter the
receptacle 49 through the mesh covered sidewall.
CA 02263002 1999-02-08
W 098/05401 PCT/GB97102120
12
Figures 9 and 10 show that the closure 47 is stepped
at the junction of the crown 48 and the skirt portion 50.
The radially outwardly extending portion of the step rests
upon the upper-edge or brim of the cup-shaped receptacle
49. The form of the closure 47 shown in Figure 10 is
designed for securing to the receptacle 49 by welding, the
weld to be formed between the radially outwardly extending
portion of the step and the upper edge of the brim of the
cup-shaped receptacle 49.
Figure 11 shows a modified form of closure 47A which
is designed to ~e irreversibly snap-fitted to a modified
form 49A of the cup-shaped receptacle. This snap fit
arrangement is similar to that described above with
reference to Figure 2. It is formed by the interaction of a
plurality of radially-inwardly directed protrusions 26A,
which are formed at spaced intervals around the inner
periphery of the skirt portion 50A of the closure 47A, with
an annular radially-outwardly projecting rib 27A which is
formed in the neck portion 55A at a location spaced from
the brim of the cup-shaped receptacle 49A. The radially
outer periphery of the upper surface of the rib 27A is
chamfered. The rib 27A divides the mesh-covered apertures
provided in the side wall of the receptacle 49A into upper
and lower mesh covered apertures 57A and 57B, neither of
2S which provides a significant resistance to flow of water
through them.
The skirt portion 50A has elongate slots 51A formed in
it to provide a flow path for water to the upper mesh
.. ... ...
CA 02263002 1999-02-08
W O 98/05401 PCT/GB97102120
13
covered apertures 57A. The lower edge of the skirt portion
50A is spaced from the sleeve portion 35A so as to provide
a flow path for water to the lower mesh covered apertures
57B.
Figure 12 shows the form of the circumferential array
of lower slots 57B. The slots 57 shown in Figure 10 would
have a similar arrangement although they would be taller.
Figure 12 also shows exemplary reinforcing ribs 58.
The length of the receptacles 7 and 49 should be
selected so that water filtering through the water filter
medium 10 contained therein does so for a sufficient length
of time to enable a satisfactory level of filtration. The
mesh size of the mesh used will also affect the rate of
water flow, so this also has to be taken into account.
The outlet at the bottom of each of the receptacles 7
and 49 which comprises the opening 36 which is covered by
the mesh 37, alternatively may comprise an insert having an
integrally molded mesh portion, which insert is inserted
into the bottom of the receptacle 7,49 so that in use water
can only escape from the receptacle 7,49 into the filtered
water compartment through the mesh of the mesh covered
portion.
It will be seen that the slots on the upper portions
of each of the cartridges are such that when the cartridges
are in use at least one of the slots is substantially level
with the bottom of the upper compartment 3 so that all of
the water poured thereinto can drain away through the
cartridge.
CA 02263002 1999-02-08
W098tO~401 PCTtGBs7/02120
14
The water filter cartridge in which the present
invention is embodied ensures that particles of the water
treatment medium cannot enter the filtered and/or
unfiltered water compartments by ensuring that a
reticulated screen, or mesh, is placed in the f~ow path of
the water so that for water to enter the filtered and/or
unfiltered water compartments, it can only do so through
the mesh.
