Water filter abstract
A water filter comprises a cap (70) having an inlet (84) and an
outlet (74), a valve (88) being provided in the inlet (84). A housing
(10) has a filter cartridge (26) removably contained in the housing.
Valve opening means in the form of a ramp like projection (56) is
provided on an upper end cap (40) of the filter cartridge (26).
The housing is connected to the cap by a bayonet fitting. When the
housing (10) is rotated to connect to the cap (70), the cartridge
(26) is also rotated, and the projection (56) contacts the valve
member (96) to open the valve.
Water filter claims
1. A water filter comprising a cap having an inlet and an outlet,
a valve being provided in the inlet, a housing connectable to the
cap to close an open end of the housing, and a filter cartridge
removably contained in the housing, and valve opening means being
provided on an upper end of the filter cartridge at the open end
of the housing, wherein when the housing is connected to the cap,
the valve opening means opens the valve, and when the housing is
disconnected, the valve closes.
2. A filter as claimed in claim 1 wherein the valve opening means
is a projection on an end of the filter cartridge.
3. A filter as claimed in claim 1 or 2 wherein the valve is biassed
to the closed position.
4. A filter as claimed in claims 1 2 or 3 wherein the housing
is rotated relative to the cap to connect the housing to the cap,
and the valve opening means engages the valve member as the housing
5. A filter as claim in claim 4 wherein a bayonet fitting is provided
for connecting the housing and the cap.
6. A filter as claimed in claim 4 or 5 wherein the valve opening
means has a sloping surface and a valve member of the valve rides
up the sloping surface as the housing is rotated.
7. A filter as claimed in any one of claims 1 to 6 wherein the
cartridge is engaged with the housing so as to rotate therewith.
8. A filter as claimed in claim 7 wherein an inner surface of
the housing and a co-operating surface on the cartridge are shaped
so that the cartridge does not rotate in the housing.
9. A filter as claimed in claim 8 wherein the inner surface of
the housing has a recess, and a co-operating protrusion is provided
on the cartridge.
10. A filter cartridge for the water filter of any one of claims
1 to 9 the cartridge comprising a body of porous material for filtering
water, the body having at one end the valve opening means, the cartridge
being readily replaceably installed in use in a housing which is
separable from the cartridge.
11. A water filter substantially as herein before described with
reference to the accompanying drawings.
12. A filter cartridge substantially as hereinbefore described
with reference to the accompanying drawings.
Water filter description
 The present invention relates to a water filter cartridge.
 Water filters are now widely used in the domestic environment.
Typically, a filter is placed inline between a main water supply
and a tap or fountain on the kitchen worktop, adjacent the sink
or basin, the filter being housed in the kitchen unit, below the
 One product, marketed by WTC Ecomaster Corporation of Minneapolis,
Minn., comprises a cap which is mounted in-line with the water supply,
and a replaceable filter unit which is a bayonet fit to the cap.
The filter unit is a plastics housing enclosing a body of filter
material. The cap has a water inlet, feeding water from the mains
supply through a waterway and down into the housing, water passes
through the filter body in the housing and then back up to an outlet
in the cap, which is connected to the tap. To facilitate replacement
of the unit without the need to disconnect or turn off the water
supply, a spring loaded valve closes the water inlet in the cap.
As the unit is twisted into position in the cap to engage the bayonet
fitting, a cam in the housing lifts the valve against the spring
to open the waterway. Similarly, when the unit is untwisted, the
cam allows the valve to drop, closing the waterway. One difficulty
with this system is that it is wasteful of material. The plastic
housing is substantial in order to resist distortion under high
water pressure up to 120 psi. It must also be sealed around the
water filter material in the housing during manufacture and so the
complete unit, housing and filter material, is disposed of. The
top of the housing is a complex moulding, incorporating both the
cam and bayonet fittings. Also, the user cannot usually inspect
the filter material (inspection may reveal nothing to the user,
but users may want to comfort of seeing the filter material).
 Another product which has been marketed for many years in
combination with a tap for delivering hot, cold and filtered water,
under the trade mark TRIFLOW and marketed by FRANKE AG of Switzerland,
utilises a cylindrical housing with a drop in filter cartridge.
The housing screws into a cap which is connected in line with the
water supply. This product has the advantage that only the cartridge
is replaced, however it is necessary to provide a manually operated
tap or valve upstream of the cap, to turn off the water supply when
changing the cartridge.
 The present invention provides a water filter comprising
a cap for connection in-line with a water supply, the cap having
an inlet water way including a valve and a water outlet, a housing
connectable to the cap, and a filter cartridge which is removably
contained in the housing, wherein valve opening means is provided
on an upper end of the filter cartridge to open the valve when the
housing is connected to the cap.
 Thus, only the filter cartridge needs to be disposed of,
while the benefit of automatically shutting of the water supply
 Also, by providing the cam on the filter cartridge, not
the housing, the user cannot install an empty housing--as the valve
will remain closed.
 Preferably the valve opening means is a projection on the
end of the filter cartridge. Preferably the cartridge is keyed to
the housing so that the cartridge will rotate with the housing,
and the projection on the cartridge is in the form of a cam or ramp
to engage and open the valve as the cartridge is rotated.
 The invention also provides a filter cartridge having the
projection at one end thereof.
 The invention will be further described by way of example,
with reference to the accompanying drawings, in which:
 FIG. 1 is a cross-section through a housing and cartridge
of a water filter in accordance with the invention, along line I-I
of FIG. 2;
 FIG. 2 is a plan view of the housing and cartridge of FIG.
 FIG. 3 is a cross-section through the water filter with
the cap in place, along line I-I of FIG. 2
 FIG. 4 is an underneath view of the cap; and
 FIG. 5 is an enlarged, partial cross-section through the
water filter along line V-V of FIG. 4.
 Referring to FIGS. 1 and 2 a housing 10 which may be integrally
moulded of plastics material, comprises a circular cross-section
cylindrical tube wall 12 closed by a bottom wall 14. A peripheral
lip 16 encircles the top, open end 18 of the tube and two opposed
lugs 20 extend outwards to form a bayonet coupling to a cap (vide
hereinafter). An inner surface 22 of wall 12 has a step 21 to form
a larger diameter upper region 23 in which two diametrically opposed
recesses 24 are formed (see FIG. 5).
 A filter cartridge 26 is suspended in the housing 10. Cartridge
26 comprises a circular cross-section outer sleeve 28 of porous
filter material such as a ceramic, and a circular cross-section
inner sleeve 30 of porous carbon filter material, such materials
are well known in the art. Sleeve 28 is capped at its lower end
34 by a plastics base 36 and at its upper end 38 by a cap 40. Cap
40 is supported on step 21 and has protrusions 42 which engage in
the recesses 24 in wall region 23.
 Cap 40 is a loose fit in the tube 12 but dimensioned so
that protrusions 42 engage with recesses 24 to ensure that the cap
40 and so the complete cartridge 26 will rotate with the housing
10. Cap 40 has recesses 44 in its outer periphery (FIG. 2) to form
channels between the cap 40 and the wall surface 23 for water to
flow into the space 46 between sleeve 28 and wall 12. Water passes,
under pressure, through sleeves 28 30 into the inner space 48 and
out through an aperture 50 in cap 40. A stub sleeve 52 surrounds
aperture 50 on the upper surface 54 of cap 40.
 Also provided on the upper surface 54 of cap 40 are two
cams 56. Each cam has a sloping surface 58 leading to a flat or
horizontal surface 60 i.e. parallel to surface 54.
 Referring to FIG. 3 a cap 70 which may be moulded of plastics
material is fitted on the housing 10. Cap 70 has internally facing
arcuate recesses 72 for receiving the lugs 20 to provide a bayonet
fitting. Also seen in FIG. 3 is an outlet waterway 74 which extends
from the centre of the cap 70 to the outer edge for connection to
a pipe leading to a tap. Waterway 74 connects with outlet aperture
50 via a channel 78 in a spigot 76 which is sealed to cylinder 52
by two O-ring seal 80. Cap 70 seals with inner surface 22 of housing
10 by an O-ring seal 82.
 FIG. 4 is an underneath view of cap 70 showing outlet water
way 74. Waterway 74 may be threaded at its outer end to receive
a pipe connector. Also shown is an inlet waterway 84 which extends
from the outer periphery 86 of cap 70 to a spring-loaded poppet
 Referring to FIG. 5 which is a cross-section at right angles
to FIG. 3 inlet waterway 84 ends in a passage 90 which connects
with the space 92 above cap 40 via poppet valve 88. Valve 88 comprises
a valve seat 94 which is screwed into the cap 70 trapping a valve
member 96. Valve member 96 is biassed by a spring 98 towards valve
seat 94. A conical surface 100 on member 96 engages a surface 102
on valve seat 94 to form a seal. An O-ring (not shown) will be interposed
between surfaces 100 102 carried loosely on valve member 96 to
form a seal.
 In FIG. 5 the housing 10 and cartridge 26 have been installed
in the cap and rotated to the locked position, bayonet lugs 20 abutting
stops 104 (see FIG. 4) when the bayonet fitting is rotated fully
home. One of the ramps 56 has lifted valve member 96 to open the
valve 88 allowing water to flow.
 With the cap 70 installed in-line between the water supply
and a tap, when housing 10 and cartridge 26 are removed, spring
98 and the water pressure push valve member 96 onto valve seat 94
preventing water escaping through passage 90. To install a filter
cartridge, cartridge 26 is placed in housing 10 the protrusions
42 and recesses 24 aligning the cartridge cap 40 and hence cams
56 relative to bayonet lugs 20. To facilitate location of the cartridge
26 as it is `dropped` in the housing 10 the upper inner wall region
98 is enlarged an a ramp 106 forms a junction with region 23 sloping
down to the upper end of the recesses 24. The cartridge and housing
are raised in position, lugs 20 passing between the sockets 72.
The cap 70 seals against housing 10 and cartridge 26 with `0` ring
seals 80 82. Housing 10 and hence also cartridge 26 is then rotated
to engage the bayonet lugs 20 in sockets 72. At about 45 to 60 degrees
of rotation, ramp 58 of cam 56 engages the bottom end valve member
96. At 60 to 90 degrees rotation, the cam 56 has lifted valve member
96 so that it rests on flat surface 60 of cam 56 and is fully open,
as seen in FIG. 5.
 By providing a rotationally symmetric fitting, the cartridge
26 can be fitted in either of two positions in housing 10 and housing
10 can engage cap 70 in either of two positions. It will be appreciated
that the shapes may be altered to ensure that the parts always engage
in one configuration only, or in more than two.
 The cartridge 26 may be keyed to the housing 10 in other
 Other modifications will be apparent to those skilled in