Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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This invention relates to a device for backwashing
the bed of particulate material in an iron filter or a water
conditioner.
As described in detail in Canadian Patent No.
1,273,721, which issued to the present inventor on September
4, 1990, backwashing devices for use in iron filters and water
conditioners tend to be somewhat inefficient. Examples of
backwashing devices are found in U.S. Patents Nos. 3,395,099,
issued to R.D. Johnson on July 30, 1968 and 3,455,458, issued
to R.D. Johnson on July 15, 1969. The Johnson devices employ
separate, spaced apart tubes. In one embodiment of the
Johnson inventions, particulate mineral is drawn into one of
the tubes in a limited area beneath the tube. The other
Johnson device involves separate, parallel tubes or a spiral
tube on a second tube. In each case, suction for backwashing
is created by means of a fine nozzle. It has been found that
such devices become clogged to the point of inoperability.
Moreover, such prior art devices cannot be used with
commercial water treatment control valves with up flow brine
controls, because the regenerative chemical will by-pass the
bed.
The device as described in the above-identified
Canadian patent goes a long way to providing an efficient
backwash device. However, a problem encountered with the
earlier invention is that of bed cementing, i.e. the bed of
particulate material, particularly in the bottom of the tank,
becomes compacted during use. The compaction or cementing is
such that the portion of useful bed is substantially reduced,
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and the efficiency of the device suffers badly. Moreover,
because of bed compaction during use of the water conditioner,
when backwashing there is no movement of water through the bed
at the lower end of the device, and consequently the water
conditioner ultimately becomes completely inoperable. It is
necessary to disconnect the water conditioner to restore water
flow for normal household use. Cementing also promotes
channelling in the particulate material, resulting in reduced
efficiency prior to complete clogging. The use of somewhat
complicated valves at the bottom end of applicant's earlier
invention also led to problems such as the reverse flow of
contaminants following a backwashing operation.
An object of the present invention is to improve
upon existing devices (including the inventor's earlier
device) by providing an even simpler backflush device which is
relatively efficient and free of bed cementing or compaction.
Another object of the invention is to provide a
device of the above defined type which is structurally simple
and durable.
Yet another object of the invention is to avoid the
use of complicated valves at the bottom end of the device
which are sensitive to particulate matter and variations in
water pressure and rate of flow.
Accordingly, the present invention relates to a
device for backwashing a bed of particulate material in a
water softener comprising tubular casing means; tube means co-
axial with said casing means and extending through said casing
means beyond the ends thereof; cap means slidable on said tube
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means for movement between a closed position in which said cap
means closes an open top end of said casing means and an open
position in which said cap means is spaced apart from said
open top end of the casing means; spring means biasing said
cap means to the closed position; opening means in said tube
means for discharging water into said cap means to cause the
latter to move away from said casing means to the open
position; first valve means including valve body means closing
the bottom end of said casing means; first passage means in
said body means in fluid communication with the bottom end of
said tube means, said first passage means being normally open
to the flow of water upwardly from the bed of particulate
material into said tube means; ball means in said body means
for closing said first passage means when the flow of water is
reversed in said tube means; second passage means in the top
of said body means communicating with said first passage
means; second valve means normally closing said second passage
means for discharging water from said valve body means when
the flow of water is reversed in said tube means; hole means
extending through said ball means; and hood means on said tube
means above said valve body means defining a venturi opening
in the bottom end of said casing means permitting the flow of
particulate material into said casing means, whereby, when
during a backflush operation water is caused to flow
downwardly in said tube means under pressure the first valve
means is closed with respect to the bed of particulate
material, water passes through said first opening means under
pressure to move said cap means to the open position, water
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CA 02140742 2001-11-22
passes through said second passage means in said body means to
open said second valve means, and water flows from the valve
body means upwardly into the bottom of said casing means to
create a venturi flow beneath said hood means and in said
casing means which draws particulate material into the bottom
end of said casing means and discharges the water and
particulate material through the open top end of the casing
means, and, when the hole means is aligned with said first
passage means, water passes downwardly from said body means
into the bed of particulate material to agitate the bed and to
prevent cementing of the particulate material.
The invention is described below in greater detail with
reference to the accompanying drawings, which illustrate
preferred embodiments of the invention, and wherein:
Figure 1 is a schematic longitudinally sectional view of
the bottom end of a water treatment apparatus containing a
device in accordance with the present invention;
Figure 2 is a side view of the device of Fig. 1;
Figure 3 is a longitudinal sectional view of the device
of Fig. 2;
Figure 4 is a side view of the top end of the device of
Figs. 1 to 3 in the open, backflush position;
Figure 5 is a cross section taken generally along line
V-V of Fig. 2;
Figure 6 is a cross section taken generally along line
VI-VI of Fig. 5;
Figure 7 is an isometric view of a section of the bottom
end of a strainer used in the device of Figs. 1 to 3;
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Figure 8 is an isometric view of a ring used in the
strainer; and
Figure 9 is a cross section of one side of the top
end of an alternate form of valve body used in the device of
Figs. 1 to 3.
With reference to Figs. 1 to 3, the backwash device
of the present invention which is generally indicated at 1 is
intended for use in a bed 2 of a particulate material mounted
in the bottom end 3 of a water conditioner tank 4. The device
1 includes an elongated, tubular casing 6. An elongated tube
7 extends through the casing 6 for carrying water into and out
of the device. The tube 7 is centered in the casing 6 by
three fins 8 (one shown - Fig. 3) extending radially outwardly
from the tube into contact with the casing 6. The fins 8 are
spaced equidistant apart around the periphery of the tube 7.
The open top end 10 of the casing 6 is normally
closed by a ring-shaped cap 11, which is slidably mounted on
the tube 7. The cap 11 is sealed with respect to the tube 7
by means of annular lip seals 13. The bottom surface 14 of
the cap 11 slopes upwardly and inwardly from its periphery for
deflecting material expelled from the casing outwardly and
downwardly. The cap 11 is biased to the down or closed
position by a helical spring 16, the flattened bottom end of
which is seated in a concave, annular groove 17 in the top of
the cap 11. The spring 16 extends between the cap 11 and the
main body 18 of a sleeve 19. The sleeve 19 is fixedly mounted
on the tube 7 by means of a screw 20. The main body 18 of the
sleeve 19 slidably supports a cap-shaped piston 22 for
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movement with the cap 11 between a closed position (Figs. 2
and 3) and an open position (Fig. 4).
The piston 22 is connected to the cap 11 by bolts 23
extending through the ring and upwardly through nuts 24 into
longitudinally extending projections 25 on the cylindrical
side wall 26 of the piston 22. The piston 22 is sealed with
respect to the body 18 of the sleeve 19 by annular lip seals
27 mounted in recesses in the sleeve. Upward movement of the
piston 22 is limited by a split ring 28 mounted in an annular
groove 29 in the bottom end of the piston. As the piston 22
moves upwardly the ring 28 engages the bottom end of the main
body 18 of the sleeve 19 which stops the piston and
consequently the cap 11. The top end 30 of the piston 22 is
sealed with respect to the tube 7 by a pair of annular seals
32. A hole 33 is provided in the tube 7 between the top end
of the sleeve body 18 and the top end 30 of the piston 22.
Water under pressure exiting the hole 33 causes the piston 22
and consequently the cap 11 to move upwardly.
The tube 7 extends downwardly beyond the bottom end
of the casing 6. A hood 35 is mounted on the bottom end of
the casing 6 above the bottom end of the tube 7. A valve body
36 and a screen generally indicated at 37 are mounted on the
bottom end of the tube 7. The annular hood 35 includes a
plastic body 39 with a harder plastic insert 40 in the bottom
inner end thereof for protecting the bottom end of the casing
6. A stainless steel sleeve 42 is mounted on the bottom end
of the tube 7 for protecting the latter. The sleeve 42
prevents holes forming in the side of the tube 7 when
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CA 02140742 2004-08-09
particulate material flowing rapidly into the gap between the hood
35 and the top of the valve body 36 strikes the tube 7.
The valve body 36 is generally cup-shaped, with a cylindrical
side wall 43, the interior surface 44 of which tapers downwardly to
a bottom wall 45 containing a central opening 46. The opening 46
is normally closed by a ball 48 with a hole 49 extending
diametrically therethrough. The top end of the body 36 extends
into an annular groove 50 (Figs. 5 and 6) in an annular cover or
top wall 52, which is attached to and surrounds the open bottom end
of the tube 7. The top wall 52 is connected to and spaced from the
hood 35 by sleeves 53 and screws (not shown) extending downwardly
through the hood into the top wall 52. The ball 48 is prevented
from blocking the bottom end of the tube 7 by a cruciform spacer
54. As best shown in Figs. 5 and 6, the spacer includes L-shaped
arms 55, the outer ends 56 of which extend upwardly into an annular
groove 58 between the bottom end of the tube 7 and the inner side
wall 59 of the groove 50.
During normal use of the device, water passing through the bed
2 of particulate material enters the tube via the screen 37. The
screen 37 includes a conical base 60 and a plurality of rings 61.
As best shown in Fig. 7, the base 60 includes a conical body 62 and
a top reinforcing rim 63 integral with the body. Four cylindrical
posts 64 in the rim 63 receive long screws 65 (Fig. 3) for mounting
the screen on the bottom of the top wall 52 of the valve body.
Small circular projections 66 are provided between the posts 64.
Similar projections 67 are provided on the top surface of each
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of the rings 61. The projections 66 and 67 act as spacers so
that there is a narrow gap between the base 60 and the
adjacent ring 61, and between adjacent rings 61 for admitting
water but no particulate material into the valve body. Each
ring 61 has small reinforcing rings 69 for receiving the
screws 65. The top surface 70 of the ring 61 slopes slightly
downwardly and inwardly, so that the passages between the
rings 61 widen slightly inwardly.
In order to backflush the particulate material in
the bed 2, the flow of water in the apparatus is reversed,
i.e. water is pumped down the tube 7 under pressure. The
water enters the valve body 36 and pushes the ball 48 against
the opening 46. When the back pressure in the tube 7 builds
up sufficiently, water entering the area between the top 30 of
the piston 22 and the top of the sleeve 19 forces the piston
22 and consequently the cap 11 upwardly against the bias of
the spring 16. When the piston 22 reaches the top of its
stroke, the split ring 28 engages the bottom edge of the
sleeve body 18. Pressure again builds up, and water then
escapes from the valve body 36 via spaced apart holes 72 (Fig.
6) in the top wall 52. The holes 72 are normally closed by a
second valve defined by a flexible skirt 73 mounted in the top
wall 52 of the valve body.. The skirt 73 includes a vertical
sleeve 75 which normally presses against the tube 7. Water
pushes the sleeve 75 outwardly and the water jets upwardly
through the casing 6 along the tube 7 (the sleeve 75 ensures a
more efficient venturi effect than the valves in the
applicant's original invention). The upward flow of water
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draws particulate material into the bottom end of the casing 6
for upward flow between the casing 6 and the tube 7 by venturi
action for discharge through the gap between the top end 10 of
the casing and the cap 11. The steel sleeve 42 ensures that
the bottom end of the tube 7 is not damaged by the particulate
material.
There is turbulence in the casing 6 which dislodges
foreign matter from the particulate material. Additional
removal of contaminants occurs when (i) the particulate
material hits the inside of the casing 6 and the outside of
the tube 7 (ii) particulate material strikes the bottom
surface 14 of the cap 11, and (iii) particulate material is
dislodged laterally against the side wall of the tank 4. Most
importantly, particulate material hits itself, i.e. particles
propelled at high speed strike each other to clean the
particulate material. The foreign matter is generally lighter
than the mineral making up the particulate material.
Consequently, the foreign matter remains in the water while
the particulate mineral settles on top of the bed 2. The
foreign matter is washed from the tank 4 with backwash water
through a conventional port (not shown) to drain.
The operation described above occurs when the ball
48 fully blocks the opening 46 in the bottom wall 45 of the
valve body 36, or when the hole 49 in the ball 48 is partially
aligned with the opening 46. When the hole 49 is more or less
fully aligned with the opening 46, water under pressure enters
the particulate material via the screen 37 to stir up the
material. Thus, the likelihood of cementing at the bottom of
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the bed is eliminated. If the hole 49 is fully aligned with the
opening 46, the water entering the valve body 36 from the tube 7 is
discharged into the bed to stir up the latter. There may be
insufficient pressure to open the second valve in the top wall 52,
and accordingly backflushing via the venturi may not occur. In any
event, the bottom of the bed is stirred up in preparation for the
next backflushing operation. Such complete or full alignment is
believed to be infrequent and accordingly backflushing usually
occurs when the flow of water in the tube 7 is reversed.
Upon completion of the backwashing operation, the flow of
water downwardly in the tube 7 is stopped, whereupon the upward
flow of water through the casing 6 ceases, because the valve
defined by the skirt 73 closes. The spring 16 returns the piston
22 and the cap 11 to the rest position on the top end of the casing
6.
Referring to Fig. 9, an alternate form of the second valve
includes small resilient nipples 77 which are mounted in the top
wall 52 at the upper, discharge ends of the holes 72. Each nipple
77 includes a frusto-conical body 78 with an annular flange 80 at
the bottom end thereof. The flange 80 is sandwiched between top
and bottom layers 81 and 82, respectively of the top wall 52. A
slit 84 is provided in the top end of the body 78. When there is a
sufficient pressure build-up in the valve body 36, water opens the
slit 84. When the pressure decreases, the slit 84 closes. The
slits 84 like the skirt 75 provide for an efficient venturi effect.
Moreover, the slits 84 define an efficient check valve for
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preventing the reverse flow of fine mineral particles in the
service mode, i.e. after backwashing has been completed. Poor
venturi and minerals in the water supply were serious problems
in the original invention of applicant.
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