Water filter abstract
A potable water filter comprising a housing having an inlet and
first and second outlets, a tube in the housing having a peripheral
wall, a passage extending through the tube, and an opening in the
peripheral wall leading to the passage, a tubular pleated filter
element surrounding the tube and a carbon filter element within
the tube. Some of the water from the inlet flows through the tubular
filter element and the carbon filter element to the second outlet.
Another portion of the water from the inlet flows along the tubular
filter element to flush the tubular filter element and then flows
out the first outlet.
Water filter claims
We claim:
1. A potable water filter comprising:
a housing having an inlet and first and second outlets;
a tube in said housing and having a peripheral wall, a passage
circumscribed by the peripheral wall and means forming an opening
in the peripheral wall and leading to the passage whereby water
from said inlet can flow in a direction having an axial component
along the tube to the opening;
means including said housing and said tube for forming a first
flow path between the inlet and the first outlet;
said passage being in essentially water tight communication with
said second outlet whereby said inlet communicates with the second
outlet through a second flow path which includes a portion of the
first flow path, the opening and the passage;
a particle filter element in the first flow path for filtering
water flowing to said opening;
a second filter element in the second flow path downstream from
the particle filter element for filtering water flowing through
the second opening, said second filter element having different
water filtering characteristics from the particle filter element;
and
said particle filter element being exposed to water flowing through
the first flow path to the first outlet whereby the particle filter
element is flushed by such flow to the first outlet.
2. A water filter as defined in claim 1 wherein said particle filter
element includes a tubular pleated filter element surrounding the
tube and the second filter element includes a carbon filter element
in said passage of said tube.
3. A water filter as defined in claim 2 wherein said tube has means
in the outer surface of the peripheral wall defining at least one
groove which extends both axially and circumferentially of the tube.
4. A water filter as defined in claim 1 wherein said particle filter
element includes a tubular filter element surrounding the tube and
said tube has means in the outer surface of the peripheral wall
defining at least one groove leading to said opening.
5. A water filter as defined in claim 1 including a deformable
flow regulator in the second flow path which deforms in accordance
with the differential pressure across it to maintain an essentially
constant flow rate through the second filter element essentially
independent from the water pressure variations at the inlet or pressure
drop across the filter elements.
6. A water filter as defined in claim 5 wherein said tube is closed
at one end and is in water tight communication with the second outlet
at the other end thereof, said second filter element includes a
carbon filter element in said passage of the tube, said particle
filter element includes a tubular pleated filter element surrounding
the tube and said tube has means in the outer surface of the peripheral
wall defining at least one groove leading to said opening.
7. A water filter as defined in claim 1 wherein said tube is closed
at one end and is in water tight communication with the second outlet
at the other end thereof, said second filter element includes a
carbon filter element in said passage of the tube, said particle
filter element includes a tubular pleated filter element surrounding
the tube and said tube has means in the outer surface of the peripheral
wall defining at least one groove leading to said opening, and said
particle filter element filters the water flowing to said opening
without filtering water flowing to said first outlet.
8. A water filter as defined in claim 1 wherein said opening and
said second filter element are positioned so that water flowing
through said opening flows through substantially the full length
of the second filter element in flowing to the second outlet.
9. A potable water filter comprising:
a housing having an inlet and first and second outlets;
a tube in said housing and having a peripheral wall, a passage
circumscribed by the peripheral wall and means forming an opening
in the peripheral wall and leading to the passage;
means including said housing and said tube for forming a first
flow path between the inlet and the first outlet;
said passage being in essentially water tight communication with
said second outlet whereby said inlet communicates with the second
outlet through a second flow path which includes a portion of the
first flow path, the opening and the passage;
a tubular particle filter element surrounding the tube in the first
flow path for filtering water flowing to said opening;
a second filter element in the second flow path downstream from
the particle filter element for filtering water flowing to the second
opening, said second filter element having different water filtering
characteristics from the particle filter element; and
said tube having means in the outer surface of the peripheral wall
defining at least one groove extending in a direction having an
axial component and leading to said opening.
10. A water filter as defined in claim 9 wherein the tubular particle
filter element is pleated and said groove extends both axially and
circumferentially of the tube.
11. A water filter as defined in claim 9 including a deformable
flow regulator in the second flow path which deforms in accordance
with the differential pressure across it to maintain an essentially
constant flow rate through the second filter element essentially
independent of water pressure variations at the inlet or pressure
drop across the filter elements.
12. A potable water filter comprising:
a housing having an inlet, an outlet and a flow path extending
from the inlet to the outlet;
a filter element in said flow path of the type which has a minimum
residence time of water passing therethrough in order to properly
filter the water; and
a deformable flow regulator in the flow path which deforms in accordance
with the differential pressure across it to maintain an essentially
constant flow rate through the filter element essentially independent
of water pressure variations at the inlet whereby the minimum residence
time can be maintained even if water pressure variations at the
inlet occur.
13. A potable water system comprising:
a housing having an inlet and a drinking water outlet;
a drinking water valve;
conduit means for coupling the outlet to the valve so that there
is a flow path between the inlet and the valve;
a filter element in said housing between said inlet and said outlet,
said filter element being of the type which has a minimum residence
time of water passing therethrough in order to properly filter the
water; and
a deformable flow regulator in the flow path which deforms in accordance
with the differential pressure across it to maintain an essentially
constant flow rate through the filter element essentially independent
of water pressure variations at the inlet whereby the minimum residence
time can be maintained even if water pressure variations at the
inlet occur.
14. A water system as defined in claim 13 wherein the housing has
a tap water outlet and said system includes a tap water valve, conduit
means for coupling the tap water outlet to the tap water valve,
a tube in said housing and having a peripheral wall, a passage circumscribed
by the peripheral wall and means forming an opening in the peripheral
wall and leading to the passage, said filter element being in said
tube and a particle filter element in the housing and outside the
tube between the inlet and the tap water outlet.
Water filter description
BACKGROUND OF THE INVENTION
This invention relates to a potable water filter which can be used
for domestic use. Water filters of this type may include a housing
having an inlet and an outlet which are connected, respectively,
to a source of water and a drinking water outlet. The water filter
includes a carbon filter element or the like through which the water
flowing to the drinking water outlet passes. A particle filter element
may also be provided to filter the water flowing to the carbon filter
element.
One problem with water filters of this type is that the particle
filter element tends to become dirty or clogged with undissolved
solids before the end of the useful life of the carbon filter element.
Consequently, the useful life of the water filter is reduced. Although
it is known to attack this problem by backflushing of the filter
elements, this has the disadvantage of requiring a reversal of water
flow through the filter. In addition, undesirable contaminant build-up
can occur during the interval between backflushes. It is also known
to flush the dissolved solids from a reverse osmosis water filter.
However, this does not prolong the useful life of the particle filter
which is located upstream from the reverse osmosis membrane.
To provide for at least a minimum residence time of the water in
the carbon filter element, a flow regulator can be utilized. The
flow regulator provides for an essentially constant flow rate through
the filter when the drinking water valve is fully open, essentially
independently of water pressure variations at the inlet or pressure
drop across the filter elements. Although this is a desirable concept,
prior art water filters have generally employed flow regulators
which are relatively expensive and complex.
SUMMARY OF THE INVENTION
This invention extends the life of a water filter of the type described
above by utilizing the water flowing to the tap water outlet of
the housing to clean or flush the particle filter element. This
increases the useful life of the particle filter element and, therefore,
extends the life of the water filter.
This concept can be embodied, for example, in a water filter which
includes a housing having an inlet and first and second outlets,
a tube in the housing having a peripheral wall, a passage circumscribed
by the peripheral wall and means forming an opening in the peripheral
wall and leading to the passage, and means including the housing
and the tube for forming a first flow path between the inlet and
the first outlet. The passage is in essentially water tight communication
with the second outlet so that the inlet communicates with the second
outlet through a second flow path which includes a portion of the
first flow path, the opening and the passage. A particle filter
element, which is preferably a tubular pleated filter element, is
in the first flow path for filtering water flowing to the opening.
A second filter element is in the second flow path downstream of
the particle filter element for filtering water flowing to the second
outlet. The second filter element has different water filtering
characteristics from the particle filter element and is of the type
which should have a minimum residence time of the water in the filter
element in order for the filter element to perform its function.
A common filter of this type is a carbon water filter.
The particle filter element is exposed to water flowing through
the first flow path to the first outlet so that the particle filter
element is flushed by such flow to the first outlet. Preferably,
the particle filter element does not filter water flowing to the
first outlet but only filters water flowing to the second filter
element.
The particle filter element preferably surrounds the tube and is
pleated. In order to facilitate the flow of water passing through
the particle filter element, the tube has one or more grooves in
the outer surface of its peripheral wall that leads to the opening
to the passage within the tube. This groove enables water passing
through the particle filter element at any region along the length
of the filter element to enter the groove and flow to the opening
in the tube. If the particle filter element is pleated longitudinally,
the groove preferably extends both axially and circumferentially
of the tube so that the pleats are properly supported and do not
extend into the groove.
This invention also reduces the cost and complexity of the water
filter by providing a simple, inexpensive flow regulator. The flow
regulator is deformable and deforms in accordance with the differential
pressure across it to maintain an essentially constant flow rate
through the second filter element essentially independently of water
pressure variations at the inlet or pressure drop across the filter
elements.
The invention, together with additional features and advantages
thereof, may be understood by reference to the following description
taken in connection with the accompanying illustrative drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an elevational view partially in section of a water filter
constructed in accordance with the teachings of this invention installed
in a domestic environment.
FIG. 2 is a longitudinal sectional view through a preferred form
of water filter.
FIG. 3 is a sectional view taken generally along line 3--3 of FIG.
2.
FIG. 4 is an enlarged, fragmentary view of a region of the water
filter.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 shows a domestic water system 11 which includes a water
filter 13 a drinking water outlet 15 a tap water outlet 17 a
drinking water valve 19 tap water valves 21 and 23 for hot and
cold water, respectively, and a suitable support, including a sink
25 on which components of the water system is mounted. The water
filter 13 includes a housing 27 having an inlet 29 coupled to a
source of cold tap water through shut-off valve 31 a first outlet
33 coupled by tubing 35 to the tap water valve 23 and a second outlet
37 coupled by tubing 39 to the drinking water valve 19. As described
more fully hereinbelow, the water filter 13 is arranged to provide
unfiltered water to the tap water outlet 17 and filtered water to
the drinking water outlet 15.
Although the housing 27 can be of different constructions, in the
embodiment illustrated, it includes a section of plastic pipe 40
and plastic end caps 41 and 43 adhered thereto. The inlet 29 extends
through both the end cap 41 and the pipe 40 and the outlets 33
and 37 extend through the end caps 43 and 41 respectively.
A tube 45 of plastic material is mounted coaxially within the housing
27 between the end plates 47 and 49. The end plate 47 is suitably
attached as by an adhesive to the tube 45 and a particle filter
element 65. The end plate 49 has flanges 54 (FIGS. 2 and 3) which
are clamped between the other end of the pipe 40 and an internal
shoulder of the end cap 43. The tube 45 is internally supported
by annular ribs 51 and 53 on the end plates 47 and 49 respectively.
The tube 45 has a peripheral wall 55 surrounding a cylindrical
passage 57 and an opening in the form of a plurality of apertures
59 closely adjacent one end of the tube. A plurality of helical
grooves 61 extend along the outer surface of the peripheral wall
55 for the full length of the tube 45.
The tube 45 is spaced radially inwardly from the housing 27 to
define an annular space 62 which forms a portion of a first flow
path that extends from the inlet 29 to the first outlet 33 and includes
the openings 63 between ribs 64 (FIG. 3) of the end plate 49 and
the end cap 43. The passage 57 within the tube 45 is in essentially
water tight communication with the second outlet 37 by virtue of
being adhered to the annular rib 51 and by virtue of having its
other end sealed and closed by the end plate 49. Accordingly, the
inlet 29 communicates with the second outlet 37 through a second
flow path which includes a portion of the first flow path, the apertures
59 and the passage 57.
A particle filter element 65 is provided in the annular space 62
between the housing 27 and the tube 45 to filter the water flowing
to the apertures 59. The particle filter element 65 can be any type
which will filter out particulate material and, in the preferred
embodiment, is in the form of a tubular, pleated filter element
surrounding and contiguous the tube 45. The particle filter element
65 may be constructed of a variety of materials, such as paper or
a suitable plastic material, and in this embodiment has pleats 67
which extend axially or longitudinally of the tube 45 for the full
length of the tube. For example, the particle filter element 65
may be a spun, bonded polymer, such as Typar, having pores which
may be as small as one micron. The particle filter element 65 can
be mounted in any suitable manner and, in this embodiment, is retained
axially between the end plates 47 and 49 and radially by the tube
45 and by peripheral flanges 69 and 71 on the end plates 47 and
49 respectively.
The particle filter element 65 has an outer peripheral surface
73 which is spaced radially inwardly from the housing 27 so that
water traveling from the inlet 29 to the first outlet 33 can pass
freely over the outer peripheral surface 73 and flush debris and
particulate matter from such outer peripheral surface. Although
it is possible that some water flowing from the inlet 29 to the
first outlet 33 may pass through the particle filter element 65
and then back out into the stream of water flowing to the first
outlet 33 it is contemplated that water flowing to the outlet 33
will be substantially unfiltered by the particle filter element
65.
The particle filter element 65 and in particular, the pleats 67
thereof, do not block the peripheral groove 61. Consequently, water
passing through the particle filter element 65 anywhere along the
length of the tube 45 can enter the grooves and flow to the apertures
59.
A second filter element 75 is provided downstream of the particle
filter element 65 and in this embodiment, the second filter element
is retained within the passage 57 of the tube 45. The filter element
75 has different water filtering characteristics from the particle
filter element 65. Although the second filter element 75 could be,
or include, a reverse osmosis membrane, preferably it is an activated
carbon filter which can enhance the taste of the water and remove
certain chemical contaminants. For example, the filter element 75
could include silver coated on carbon and/or antibacterial resins
impregnated in the carbon. As such, this kind of filter element
requires that the water have a certain minimum residence time within
it in order that the proper and complete filtering action can be
carried out. In this embodiment, the filter element 75 is cylindrical
and completely fills a substantial length of the passage 57 and
is retained in the passage 57 by porous retainers 77 at its opposite
ends.
A flow regulator 79 assures that the water passing through the
filter element 75 will have at least a minimum residence time therein.
The flow regulator 79 is in the form of a deformable, cylindrical
rubber or plastic washer having a central orifice 81 which opens
downstream into a conical recess 83 which widens radially as it
extends downstream. For example, the flow regulator 79 may be of
the type manufactured by Vernay Laboratories. The flow regulator
79 is carried by a tubular fitting 85 which is received within an
annular boss 87 of the end plate 47 and is attached to the end cap
41. More specifically, the flow regulator 79 is received within
an inwardly opening cylindrical cavity 89 and the conical recess
83 faces a rigid, annular shoulder 91 of the fitting. An annular
seal 93 seals the interface between the fitting 85 and the boss
87.
In use of the water system 11 when the user opens the drinking
water valve 19 water flows from the inlet 29 through the particle
filter element 65 the grooves 61 the apertures 59 the filter
element 75 the orifice 81 and the tubing 39 to the drinking water
outlet 15. If the differential pressure across the flow regulator
79 is relatively high as would occur when the water pressure at
the inlet 29 is high and/or when the filter elements 65 and 75 are
relatively clean, the flow regulator is forced against the shoulder
91 and deformed to reduce the diameter of the orifice 81. In this
event, the flow regulator acts to reduce water flow therethrough
to maintain a residence time of the water in the filter element
75 which is at least equal to the minimum desired residence time.
On the other hand, if the pressure at the inlet 29 is relatively
low, such as when either or both of the filter elements 65 or 75
are partially clogged, the differential pressure across the flow
regulator 79 is reduced. Consequently, the deformation of the flow
regulator and the resulting constriction provided by the orifice
81 is reduced so that the water flow rate through the filter element
75 with the valve 19 open, is maintained essentially constant essentially
independently of water pressure variations at the inlet 29 or the
pressure drop across the filter elements 65 and 75.
If the tap water valve 23 is opened, water flows from the inlet
29 through the annular space 62 between the housing 27 and the filter
element 65 the openings 63 the outlet 33 and the tubing 35 to
the tap water outlet 17. As described above, this water is essentially
unfiltered by the filter elements 65 or 75. However, this flow of
water longitudinally of the pleats 67 and the filter element 65
flushes debris and particulate material from the particle filter
element 65 to clean it and extend its useful life.
The tubing 35 and 39 can be coupled to the water filter 13 in any
suitable manner, such as by fittings 95 and 97 threaded into the
outer end of the fitting 85 and into a separate internally threaded
fitting 99 carried by the end cap 43. Another suitable fitting 101
may be utilized at the inlet 29.
It should be understood that the flow regulator features of this
invention, such as use of the deformable flow regulator 79 can
be employed with or without the particle filter element element
65 and with or without the grooves 61 on the tube 45. In addition,
the use of the grooves 61 which extend both axially and circumferentially,
can be used with a longitudinally pleated filter element either
with or without the flushing of the filter element 65 the second
filter element 75 and the flow regulator 79. Of course, in the preferred
form of the invention, all of the features are utilized together.
Although an exemplary embodiment of the invention has been shown
and described, many changes, modifications and substitutions may
be made by one having ordinary skill in the art without necessarily
departing from the spirit and scope of this invention. |