Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~(~3646~
; APPARATUS FOR
'1 ., ~ .
~ r- -
24 ~eavy trucks, eaxthmovers and ~imilar off-the-road equipment ~
customarily include an air filter for removing dust from the air .
26 intake to the engine, ~hereby protecting the engine. Such air
27 cleaners commonly have one or more cylindrical ~ectio~s in each
28 of which a pleated paper air filter element is positioned so tha~
29 t~e intak~ air to the engine is pass~d through the porou~ paper
3 . . . :'
32 . . . .
1 , '.'~ __ . .. , _ ... _.. _... .. . _ _
`" ~ ''' , '
11 ' ' ,
103t;46~
1 of the ~ilter. Any dirt, grit, or other foreign r~terial i8
2 caught by ~he filter while the air pas~es so that i~ i8 prevented
3 from entering the engine. When the~e filters have a~cumulated a
4 substantial layer o~ dust, dir~ and other debris, somet~mes
S including oily material, they are removed and either discarded
6 or cleaned.
7 In recent years, such cylindrical pleated paper filter~ have
8 been made of resin impregnated paper which can be washed in order
to remove accumulated dirt and debris ~o'~ha~ tha filter element
can be reused many times, thereby effe~ting a very sub~tantial
- cost saving without significantly decrea~ing the fil ering
12 eficiency of the air ~iltar. Manual washing of the air filters
13 involves a ~ubstantial amount o~ labor and i8 not customarily
14 economical.
. Inspection of cleaned air $ilter~ is also impor~ant ~
assure that no holes or tears are present in the filter paper .
1 that would permit dust par~icle~ to pa~s ~hrough and damage the
1 engine. It is not only important to have thorough inspection
1 with high reliability, but also it i~ desirable to provide the
2 inspection at an early stage of the cleanin~ operation if .
2 possible to minimize ~he extent of cleaning given to a filter .
2 that is defective and need be discarded. Previously it has been
2 the practice t~ clean the filter complately prior to inspection.
2 Although a large proportion of heavy equipment employs
2 canister-type air filters having a fluted membrane of paper in .
2 the general form of a cylinderO another type i8 also employed
27 that has resisted efforts to clean. ~his typa of filter has a
2 pair o~ rigid headers between which cylindrical pleated paper
3 filter elements are arsanged. ~oles through one header provide
3 . .
1036~6~
access to the inte~ior of each of the filter paper tubes and the
other end is closed. The~e filters are typically rectangular and
have ~ro~ four to sixty-four tubes in commercially available
embodiments. ~n such embodiments the hole through the header
leading to the interior of the tubes is in theorder of one inch
diameter making it quite difficult to introduce a suitable washing
nozzle. Access to the outside of the tubes is restricted since
the adjacent elements prevent access to the elements from all
sides. It is therefore desirable to provide a technique for
cleaning and inspecting such filters, preferably by mea~s of
automatic or semi-automatic equipment.
With the best washing techniques previously available,
it has been found that only a limited number of cleaning cycles
can be performed on a filter before its ability to pass air is
significantly diminished. Typically, after three or four washing
operations the ability of the filter to pass air is diminished
to the extent that it can no longer be used and must be discarded.
It is therefore desirable to provide an improved washing technique
that does not significantly diminish the air passing character-
istics of an air filter.Brief Summary of the Invention
In accordance with the present invention there is
provided apparatus for cleaning a filter or the like having a
liquid wettable porous membrane normally dirty on the inside
and clean on the outside comprising:
means for at least partially closing the end of the
filter;
means for moving a source of forceful flow of water
adjacent the dirty side of the filter for impinging on different
regions of the filter membrane at different times for dislodging
~ _ 3 _
B
)36461
surface dirt therefrom and fox pre~sur~æing the pa~tiall~ closed
i.nside portion of the filter for forcing water through the filter
membrane from the normally dirty side to the normally clean side
to displace particles from the pores of the filter membrane; and
partially open vent means at the closed end of the
filter for discharging a portion of the flow of water from the
vent means so that only a portion of the flow of water is discharged
through the filter membrane.
Also in accordance with the invention there is provided
apparatus for cleaning a cylindrical filter or the like having
a liquid wettable porous cylindrical membrane having pleats
extending along its length and normally dirty on the inside and
clean on the outside comprising:
means for at least partially closing the end of the
filter;
nozzle means extending through the closed end for
impinging a forceful flow of water against the filter membrane
in a direction along the pleats and at an angle to a normal to
the pleats;
means for moving the nozzle along the length of the
filter for dislodging dirt from the pleats; and
partially open vent means at the closed end of the
filter for discharging a portion of the flow of water therethrough
for carrying surface dirt whereby another portion of the forceful
flow passes through the filter membrane for dislodging dirt from
the pores thereof.
- 3a -
B
~36461
Drawings
Other features and advantages of the present invention
will be apparent ~rom the following detailed description of a
presently preferred embodiment when considered in connection
with the accompanying drawings wherein:
FIGURE 1 illustrates semi-schematically an arrangement
for cleaning and inspecting an air filter element in a ban~ of
similar elements;
FIGURES 2 and 3 illustrate in end and side views a
form of nozzle useful for cleaning and inspecting air filters;
FIGURE 4 illustrates semi-schematically an improved
means for cleaning an air filter element;
FIGURE 5 illustrates means for cleaning a plurality
of air filter elements; and
FIGURE 6 illustrates a cleaning arrangement for a
cannister type filter.
Description
It has been found that the reason air filters lose
their ability to pass substantial quantities of air as washings
are repeated lies in gradual blocking of the pores in the paper
by very fine particles. Most air filters of the type involved
in practice of this invention, are employed in trucks or con-
struction equipment operating in environments where motor oil
and exhaust fumes are present. Apparently oils, unburned hydro-
carbons, and the detergents in the motor oil accumulate in thepaper filter element during operation. This is believed to
produce a surface that has a high affinity for small particles
and does not readily yield these particles under normal cleaning
operations. Thus, as time progresses, the oils and associated
particles accumulate in the filter until it is effectively
plugged. It is believed that
- 4 -
~1[~646~
the relatively coarse particles seen on the surfaces o~ a
dirty filter are of appreciably less significance in blocking
air passage through the filter than are the fine particles
trapped in the pores of the filter paper by the oils and
detergents.
It has been found to be desirable for cleaning filters
to employ an arrangement where at least a portion of cleaning
liquid is forced through the filter paper so as to dislodge the
oils and particles contained within the fine pores thereof.
Since the fine particles are to some extent retained
by the oils, detergents and unburned hydrocarbons within the
filter, it is found to be particularly effective to saturate
the paper filter membrane with hot soapy water for dislodging
the oils and particles. Hot soapy water is forced through the
filter paper by impingement or pressure so that flow through
the paper assures saturation. By soapy liquid it is not
intended to refer only to soaps, but also to detergent solutions
that may be effective in removing oils, unburned hydrocarbons
and dirt.
The effectiveness of the cleaning technique where the
cleaning liquid is forced through thé filter membrane is shown
in a very surprising manner. The efficacy of cleaning wherein
cleaning liquid is forced to flow through the filter membrane
is substantially the same whether the flow is from the dirty
side towards the clean side or from the clean side towards the
dirty side. Thus, it is found that the critical feature is
flow through the paper filter and not necessarily back-flushing
through the filter.
Thus, for example, when a dirtv filter has hot soapy
water forced through it from the dirty side toward the clean
side, substantially clean water flows through for a few seconds.
1~364~
Thereafter the water flowing through the filter is visibly dirty
and once this occurs, it appears certain that the hot soapy
water has soaked into the pores where dirt is entrapped. There-
after forcing of additional soapy water or cold clear rinse
water through the paper is effective in substantially completel~
restoring the filter to its original condition. One such
filter soaked with hot soapy water and rinsed with cold clear
water, at least one of which was forced to flow through the
filter paper, has been cleaned and re-used sixteen times
without noticeable deterioration in the ability to pass air.
One type of air filter element sometimes employed in
trucks, earth moving equipment and the like, and apparatus for
cleaning such a filter are illustrated semi-schematically in
FIGS. 1 and 5~ As best seen in FIG. 5, this type of filter is
typically rectangular with a plastic layer 116 on one face and
a plastic header 117 on the opposite face. Mounted in between
the opposed plastic sheets 116 and 117 are a plurality of
cylindrical filter elements 118. These filter elements are
typically about 9 inches long and 2 to 2-1/2 inches in diameter.
; 20 They are formed of pleated paper with the pleats (not shown)
about 1/4 inch deep running along the length. One end of
each paper filter element 118 is embedded in or sealed to the
end plastic layer 116. The opposite end of each filter element
is embedded in or sealed to the plastic header 117. A plurality
25 of holes 119 through the header 117 communicate with the inter-
ior of each of the paper filter elements 118. From 4 to 64
filter elements are conventionally used in air filters of this
type.
When a filter of this type is used, the air flow is
; 30 through the holes 119 into the interior of the separate filter
~03t;~61
paper tubes 118. The air passes through these filter elements
and thence through a surrounding perforated sheet (not shown)
en route to the engine. Dirt therefore accumulates on the
inside of the tubes rather than on the exterior as is more
common in the canister-type filters. Previously there has
been difficulty in cleaning this type of filter since the holes
119 are typically about 1 inch in diameter and access by washing
nozzles is therefore difficult. The successive cleaning of the
separate filter tubes 118 in the assembly is time consuming and
has generally proved uneconomical.
It has been found that thorough and economic cleaning
of a filter of the type illustrated in FIG. 5 can be accom-
plished in practice with this invention. The first step of
cleaning may be to vacuum the interior of the tubes by placing
the inlet of a conventional vacuum cleaner over the holes 119,
either individually or in groups. This draws air in a reverse
direction through the paper filter elements and the rather
large loose dirt that accumulates within the filter elements
is largely removed. Effective cleaning has been obtained
without this step and it may be deleted in most instances.
The next cleaning step is to thoroughly saturate the
paper filter elements with a cleaning liquid which is prefer-
ably hot soapy water which loosens the oils, detergents and
unburned hydrocarbons within the pores of the filter paper,
thereby loosening the fine dirt particles therein. Although
saturation can be obtained by merely filling the cylindrical
paper elements with hot soapy water, it is preferable to employ
an aerating nozzle that is pressed into the hole 119 so as to
engage the sides and effect a degree of sealing so that the
interior of the paper
-- 7
; ~13646~1,
1 filter elements 118 is slightly pressurized with the aerated
2 li~uid. This forces the hot soapy water to ~low through the pape~
3 filter element and quickly effects ~aturation and remo~al o~
4 trapped fine dirt particles. .
S The presence of aeration in the soaping or rinsing l i~uid
6 is desirable since any perfora~ions, ~ears, pin holes or the
7 like permit the air bubbles to pass and result in a ~low o~
8 bubbles on the outside o~ the ~ilter element which are readily
9 noti~ed by the operator. I~ no bubbles are seen, the filter .
i~ sound and can be restored to service.. The aerated water
11 inspection technique is particularly valuable with a filter of
12 this geometry be~ause visual inspection is extremely difficult.
13 When aerated water is forced to flow through a ~ilter a
14 sound filter paper membrane permits the water to percolate
through and heavy flow can be seen on the opposite side. Air
16 entrained in the water is either diverted on the side where the
17 nozzle is, or, there is good reason to believe, a substantial
18 portion o~ the air also passe~ thxough the filter in sufficie~tly
19 fine dispersed streams or bubbles that no visible bub~les are
seen on the far side from the nozzle. Thus, in a sound ~ilter lt
21 appears to the obser~er that only water is pas-~ing through. .
22 If, on the okher hand, there is a small hole or tear in the
23 ~ilter paper membrane, the flow of air is relatively unrest~icted
24 and a strea~ of bubbles Lmmediat~ly appears at the location of the .
2~ hole. It has been found that this flow of air bubbles through
: 26 the filter paper provides a very sensitive and reliable test for
27 holes and tears, even those suf~iciently small that they are
28 difficult to find by conventional light inspection techniques. :
29 Holes ad~acent the ends of the filter where light inspection
31 . .
32
, .
Il 8
~ ~0369bl
1 ¦ techniques are ~O~uitable, ara also found with acility by
2 I forcing aerated~ against the filter element w~th su~icient
3 ¦ ~orce ~hat a su~stantial amount of water i~ forcQd through th~
4 ¦ paper.'
5 ¦ A particular advantage ari~e~ ~rom the detection of hole~
6 ¦ and tears by ~orceful flow o~ aerated water since both cleaning
7 ¦ and inspection can be combined in ~ single operation. 8ince the
8 ¦ test begins at ~he very beginning o~ the cleaning cycle, any
g ¦ filter that shows the presence o~ pin holes or tears can be
10 ¦. immediately withdrawn ~rom the clea~ing cycle and discarded,
11 ¦ thexeby saving the additional expenditure of time required to
12 ¦ clean the fil~er before inspection. It will also be no~ed that
13 ¦ inspec~lon of the entire filter paper i~ obtained both during
14 ¦ the initial cleaning cycle and also during ~he rinsing cycle
15¦ so that the chances o~ overlooking a p~n hole or tear are signifi-
16 ¦ cantly reduced. During cleaning a substantial pressure gradie~t
17 ¦ is prodl~ced across the fil~er membrane and weak ~ilters that
18 ¦ might rupture during.use are dete~ted since they rupture during
19 ¦ the cleaning operation. It will be noted tha a wet filter during
20 ¦ the washing operatio~ is not a~ strong as the dry filter actually
21 ¦ put into service. Thus, it will be saen that during the cleaning
22 operation, quick and reliable pressure, ~low rate, and lealc inspec-
231 tion is obtained. . `
241 By using an aera~ed f~ow o~ wa~er ~gainst the filter after
251 cleaning in the automatic station, any leaks in the ~ilter ca~
26 be detected at an early stage before all of the clea~ing operatio~
27 have been completed. ~fter was~ing the filters in the disclosed
28 apparatus they are dri~d for many hours at low temperature in a -
29 foroed drying oven ~pr complete drying without damaging the
31 resins in ~he paper. After prolonged drying, the fil~ers ~re
32
i
_ .
~);3 6461
inspected with bright lights for holes or tears. B~ detectiny
such holes or tears irnmediately after washing, the fil~er can
be immediately discarded instead of going through the drying
and subsequent inspection cycles, thereby effecting a substan-
tial saving o time and effort.
FIG. 1 illustrates semi-schematically in transverse
cross-section an arrangement found suitable for cleaning filters
of the type illustrated in FIG. 5. Thus, as illustrated in
this embodiment, a special nozzle 121 is inserted into the hole
119 through the header 117. This nozzle has a hollow body 122
concentric with an inlet tube 123. The upper end of the tube
123 beyond the body is threaded to fit a manifold 124 indicated
only schematically. At its lower end, the body is constricted
to fit within the hole 119 through the header 117. ~he tube
123 which may be either straight or tapered extends down to
the constriction and is pinched into a nozzle tip 126 like that ~-~
illustrated in FIGS. 2 and 3. A threaded side tube 127 communi-
cates with the interior of the body.
Referring again to FIG. 1, a valve A connects the
; 20 manifold 124 to a supply 128 of washing liquid which is typically
hot water containing a suitable soap or detergent. A second
valve B connects the manifold to a source 129 of rinsing liquid,
such as, for example, clear, cool water. A third valve C is
connected to the side tube 127 for selectively closing this
tube which otherwise vents to the ambient. The three valves may
be manually operated, or preferably are air or vacuum operated
for quick response. For some applications the valve C can be
merely a tube that can be momentarily closed with the operator's
thumb.
-- 10 --
~ ;461
1 For cleaning the filter element 118, a valve C i~ left open
2 to vent the interior of the body 122 to ~he outside. First,
3 the valve A to the soapy water supply is opened to admit soapy
4 water through the ~ozzle tip 126 into the interior of the filter~
Since a dirty filter is typically nearly plugged up with dirt, a
6 pressure of about 20 psi is used to avoid rupturing normally
7 sound filter elements. ~ portion of the water-comlng through the
8 nozzle tip dislodges heavy dirt that may have accumulated within
the filter element and discharges thi~ dirt through the vent
10¦ valve C. ~Because of this, it is often possible toldelete the
11¦ above-me~tioned ~tep of vacuuming the filters befor~ cleaning.)
12¦ Another portion of the hot~ soapy water soaks into and through
13¦ the papPr of the filter element. When ~uch dirty water ~8
i 14¦ observed ~lowing freely from ~he outside of the filter, i~ can be
15¦ assumed that the paper is sufficiently saturated. Typically in
16¦ most filters, onl~ a few seconds are required to sufficiently
17¦ saturate the paper. Thereupon, the valve A is closed~
18¦ Next, the ~ilter is rinsed ~y opening the valve B to the
19 ¦ source of rinse water. Because some of the dirt has been dis
20 ¦ lodged i~ ~e washing operation, a higher pressure, typically
21 ¦ about 40 psi, may be used for the ri~se water. I~itially, rinse
22 ¦ water flows ~hrough the ve~t ~alve C and through ~he pa~er of
23 ¦ the filter element. This serves to dislodge additional dirt
24 ¦ from within the filter elemen~ and dischaxge it through the vent.
25 ¦ A~ ~he rinsing proceeds, the very ~ine dirt lodged in the
-26 ¦ paper of the filter element-is washed-out and more and more water
27 ¦flows through the paper filter element itself. It is found that
28 ¦as the water flowing through the filter and spillin~ through the
29 ¦vent becomes clear and free of dislodged dirt, the flow out t~rough
30 ~
32 !
~ .
11
,
' 1~ ~64U~
1 the vent diminishes and the venturi action of the nozzle tip 126
2 within the constricted portion of the body 122 begins to draw alr
3 in through the vent valve C. Su~pris~ngly, at the same ~ime water
4 may be flowing out of the vent and air ~lowing in. ~he result
that the vent, the noz~le body, and the interior sf the ~ilter
6 element are f~lled with aerated water under moderate pressure.
7 If there is a leak in the filter element, this aera~ed wate~
8 ~lows through and provides an excellent indication o~ the leak
as hereinabove described.
W~en the water flowiny ~rom the ~$1~er and vent are
11 substan~ially clean, ~he vent valve C i~ ciosed for one or two
12 seconds. Since the rinse valve B i8 still open, the pressure on
13 the aerated water within the filter el2ment increases and any
14 leaks are even more apt to be detected. In addition, the gua~tity
of water flowing through the filter element is observed and
16 permanently plugged filters can be diæcarded. Since the interior
17 o~ the filter element is pressurized, a pressure test is also
i 18 provided for detection of weak filter elements. SometLmes weak
19 ~ilter elements, leaks, and poor flow rate can be detected during
the washing or rinsing steps and the fil~er can be discarded
; 21 before reac~ing the inspe~tion stepwhere the vent valve C is
2Z closed.
23 The valve positions during ~he cleaning and inspection
24 cycles oan ~e summarized in *he following table:
26 - ~ ValVe_A V~lve D Valve C
27 Wash Open Closed Open
28 Rinse Closed Open Open
291 ~es~ Closed Open Closed
31j .
3~ !
.1, ,''
, 12
. . ~ .
~ 461
1 After rinsing with the cold clear w~ter it i8 pre~erred to $nvert
2 the fil~er assembly and spray the exterior with clear water to
3 wash off any dirt particles tha~ may be on ~he exterior. Af~er
4 washing, the filters are dried in a low temperature oven in a
conventional manner.
6 I~ will be noted that with this cleaning arrangement the
7 flow of cleaning liquids is from the dirty side of the ~ilter
to the clean side. However, it has ~een found that with such
9 technique the cleani~g i5 every bit as good as can be obtained
with a reverse flush which, because of the geometry of this
11 filter, would be somewhat difficult to obtain.
12 Preferably, the nozzle is of a type giving an aerated spray
13 preferably in a general fan shape so as to best impinge within the
14 pleats of the filter paperO Typically, aerated water has en-
trained bubbles of air so that the water is a substantially
16 continuous phase and the bubbles are discontinuous. This is to be
17 distinguished from a jet spray of water which is either a con$inu-
18 ous stream of water without bubbles oÆ air or is in the form of
19 discrete droplet~ of water wherein air would be the substantially
continuous phase and the droplets would be discontinuous. Co~-
21 ventional aerating nozzles such as very commonly used in kitchen .
22 ~aucets and the li~e are suitable.
23 An inexpensive noz~le that has proved particularly suita~le
24 for thorough cleaning o~ air filters is illustrated in FIGS. 2
and 3 which comprise end and side views, respectively, of the
-Z6 very simple nozzle. Typicallyr such a nozzle is formed by merely
27 pinching the end of a piece of copper tubing 111. The end is
28 pinched from two sides so that the tubing collapses towards a
291 general gure a shape transverse to the direction of fluid flow,
32 . ` ~'
13
, . . . .
~0~646~
1 A tube 23 extends through the enlarged body 22. A packing
2 nut 31 is threaded onto the ~ody and captures an 0-ring 32. This
3 arrangement permits the tube 23 tG be ~lidably moved up and down
4 through the nozzle body and into the ~nterior of the ilter
element 18~ Rotation of the tube is al50 permitted. A nozzle
6 tip 26 is provided on the end of the tube 23. The nozzle 26 i8
pxeferably merely an end of the ~ube pinched in~o a figure 8
8 configuration as hereinabove described and illustrated in FIGS.
9 2 and 3. Typically, for example, the tube 23 is a one-hal~ inch
copper tube with its end pinched to ~orm the nozzle 26.
11 The hasic mode of operation of the filter washing arrangement
12 illustrated in FIG. 4 is similar to that hereinabova described.
13 It has been found desirable, however, ~or extremely dirty filters
14 to provide a washing a~tion that directs a forceful flow of fluid
into ~he pleats of the filter. Such forceful flow is obtained
16 by sliding the tube 23 up and down through the nozzle body so
17 that the nozzle tip 26 mov,es within the ~iltex elemen~. The tube
18 is also rotated since the nozzle tip 26 has a fan shaped spray
19 wi~h its axis on the axis o~ the filter ele~ent. This fan shaped
flow of water reaches into the deepest creases of the pleats and
21 di~lodges any dirt trapped therein. By rotating ~he tube a~d
22 moving it up and down all of the p~eats can be rapidly and
23 thoroughly cleaned. Manua~ moving of the tube has proved
24 sati~factory.
The nozæle having a downwardly directed flow of wa~er in a
-26 generally ~an shape has proved to be eminently satis~actory. The
27 downwardly directed flow of water impinges on the filter membrane
28 at an angl e and appears to be better in opening the pleats and
Z9 1~ reaohin the deepest ~olds thereo~ than a sprdy o~ water directed
31 .
32
. 1,
1~ . ' ' ~i
. , ,'
1~461
1 ¦ as seen end on in FIG. 2. The pinching causes the tube to bulge
2 slightly in a direction transverse to th~ d~rectio~ o~ pinching
3 so that the pinched end has a pair of slightly bulging lobes 112
4 separated by a ~arrowed waist 113. In a typical embodiment, the
waist 113 has an inside width about one-third or less o the
B inside diameter of the tubing 111. ~ nozzle ormed in this
7 manner provides a fan-shaped spray with an included angle o~
81 about 20-25 and ~y greater pinching can be 60-90. It is
; 91 believed that the velo~ity of flsw near ~he center of the ~an-
10¦ shaped spray is higher than near the edge and thatlin ~he region
11 near the nozzle air is entrained to some degree in ~he water so
12 that the water can be considered to be aerated, even though not
13 so much so as with a conventional aerating nozzle such as employed
14 in kitche~ sinks and the like. If desired, air can be in~ected
in the water stream a considerable distance upstream from the
6 nozzle.
17 ~IG. 4 illustrates semi-schematically in longitudinal cross~
18 section a variation in the filter washing apparatus illustrated
19 in FIG. 1. As in that embodiment the filter comprises a bottom
layer 16 and a top header 17 having a plurality of pleated paper
21 filter elements 18 thexebetween. A noz~le head 21 has its nose .
22 inserted in a hole in the header to communicate inside the filter
23 element 18. ~he nozzle head has an enlarged body 22 converging
24 at its lower end to provide a tight fit with the hole through the
filter header 17. If desired, a resilient layer may be provided
26 on the tapered nose of the nozzle head to provide a fluid seal'
27 to the header. ~ side vent 27 communicates with the interior of
28 the body. The side vent may lead to a valve, or as mentioned
29 above, may be temporarily plugged ~y the operator's thumb ~o
331 provide filter inspection.
32 .
! 14
i
;. , . . , , I
. , , I
- ~ l
6461
1 radially outwardly normal to the pleats. In addition, the
2 downwardly directed flow stirs up any dirt that would tend to
3 settle in the ~ottom of the closed end o~ the ~ilter element
4 and e~train it in the escaping water to ~low out o~ the vent 27.
This f an shaped spray is also desirable since it pérmits a strong '
6 flow of downwaxdly directed water in spposite portions oP the
7 ¦ interior of the filter element while at the same time, ninety
8 ¦ degrees away, there can be a strong upward f.low permitting the
¦ water and entrained dirt to be discharged from the top o~ ~he
10 ¦ ~ilter element. The nozzle tip producing a fan ~haped spray
11 ¦ also serves ~o suck in air and ~ill the interior of the filter
12¦ element with aerated water, Such aeration is particularly vigorou!
131 when the tube and nozzle tip are withdrawn from the filter elemen~¦
1~1 to a position approximately as shown in FIG. 1. It will be
15 ¦ apparent that other nozzle tips may be suitable. Thus, for
16 ¦ example; a tip may be used with two or three holes extending
17 ¦ radially downwardly for impinging a flow of water on the filter
18 I element at an angle. This would be generally fan shaped even
19 ¦ with little ~low along the axis and most flow radially down.
20 ¦ Soapy wash water and rinse water are successively applied
21 ¦ through the tube 23. Preferably the washing and rinsing action .
22 ¦ starts with the nozzle tip 26 about one-half inch from the bottom
231 f the filter element and it i~ then drawn up and down a few ¦ .
24 times as it is rotated to carry out any entrained dirt. After
such washing and rinsing the vent 27 is closed for a short
26 interval for ~inal inspection and pressure testing o~ the~fllter -1`
27 element.
28 FIG. 5 illustrates semi-schematically apparatus for auto-
29 matically cleaning several elements of a filter according to the
. l~.
31
32
11 .
I lS `
~ . . . .. . .. _ . .. . .. ... .... , ., .. . _ .. . .
1 1~;~6;46:1
1 above-described tech~ique. The larger filters commerclally
2 available have ~he paper elements arranged ln rows of four or
3 eight and to increa~e filter siæe ~dditional rows are added. The
4 semi-automatic cleaning apparatu thereore has a pair of cleaning
5 heads 123 and if desired additional heads can be coordinated with
6 the illustrated pair. Each of the cleaning heads comprises a
7 ¦nozzle 121 as illustrated in FIG, 1. Each nozzle i8 tapered at
8 ¦lower end so as to fit ~nto and provide a partial ~eal on the
91 hole 119 to minimize leakage of water from within the filter
lO elements and thereby maintain a degree of pressurization therein.
11¦ If desired, a resilient rubber seal (not shown) can !be employed
12¦ on the nozzle to afford a better seal. A spring may be used o~
13 each nozzle 121 so th~t they are individually biased towards the
14 filter tc be cleaned so that an entire bank of cleaning heads can
15 be brought down against a filter and all of the cleaning heads
16 can seal against the holes ll9 wit~ approximately equal force.
17 The several cleaning heads 123 are connected to a liquid
18 manifold 124, illustrated only schematically. The manifold is
l9 connec~ed to the wash liquid 128 by a valve A. A second valve B
; 20 connects the manifold to a supply of rinse water 129. To use the
21 semi-automatic cleaning equipment, the pair of cleaning head~ 121
22 is brought down against ~he filter so that the nozzles close ~he
23 holes ll9 and the valves are opera~ed in the above-described
24 manner for cleaning and inspecting the filter. If desired
25 internal ~ubes can be raised and lo~ered or thorough cleaning
-2~1 in~ide the-~filter--elements in-the-man~er hereinabove ~described ~
27¦ and illustrated in FIG. 4.
28 It has also been found that the cleaning action is obtained
29 when a tube having a nozzle that directs water laterally is
31 moved inside each chamber of ~he filter without a sealing head In
32
I . ',
1' 17
~ _, . . . ~
~L036461
place. If one merely inserts a tube like tube 23 in Fig. 4 in
the filter withou~ any nozæle 21 in place, good washing action
is obtained, The impingement causes heavy water flow through
the filter as well as out of the end. The ability to pre~suriz~
for detecting leaks is diminished although i~ large leaks are
present areated flow may be seen. This type of cleaning alone
can be done manually by moving the tube within the ilter chamber.
This can be done as a substitute for the combined cleaning and
inspection described above, or can be a preceeding step. Thus,
one can wash manually with hot soapy water and subsequently
rinse and inspect with cold clear water.
Fig. 6 illustrates semi-schematically a nozzle arrange-
ment for foxcing cleaning liquid to pass through the pleated
paper filter element of a filter in the form of a cylindrical
cannister. Thus, as illustrated in this embodiment, a filter 101
of a cylindrical canister type is seen in end view. A small
portion is cut away to illustrate the accordian folded pleats of
the paper filter membrane 102. An inside pipe 103 supports a
nozzle 104 directed towards the inside of the filter 101. On
the outside of the filter a second pipe 106 supports a nozzle
107 directed towards the outside of the filter. The two nozzles
104 and 107 are displaced from each other around the circumference
of the filter so that the sprays from the nozzles each impinge
on different areas of the filter. Preferably, each of the
nozzles is of a type giving an aerated spray preferably in a
general fan shape so as to best impinge within the pleats of
the filter paper 102.
In order to loosen oils, unburned hydrocarbons and the
like that trap dirt within the pores of the filter paper, the
paper is saturated with soapy water. One technique that has
- 18
~0~6~1
been employed satisfactorily is simply to lay the ilter on its
side on the substantially horizontal rollers and add hot soapy
watar to the interior. The soapy water soaks into the paper
as it is slowly rotated and drips from the outside. At first the
water coming through is clear and ~ubsequently it becomes
dirty, indicating the ~aturation of the paper has occurred and
some of the dirt is being dislodged. The filter can then be
rinsed by forcing water against the ~urface so as to flow
through the filter paper membrane, thereby dislodging the soapy
water and the oils and dirt in the paper.
Still another way of applying the hot soapy wa$er is
with the filter arranged vertically and on a turntable that
permits rotation at a sufficient speed to force water through
the paper. According to this technique the filter is arranged
with its axis vertical and rotated about this axis while hot
soapy liquid is applied on the interior either along substant-
ially the entire length of the filter or at least near the top
portion from whence it can flow downwardly. The filter is
rotated at a speed such that the acceleration is at least one
g, that is, the centripetal acceleration is equal to or greater
than the acceleration of gravity. Thus, the hot soapy water is
forced to flow through the filter paper membrane with a force
; that is at least equal to that when the hot soapy water is
added in a filter lying in a horizontal position.
As one example, a 12-inch-diameter filter is rotated
at about 100 rpm which gives an acceleration of 1.7 g, and it
is observed that a greater flow of hot soapy water occurs
through the spinning filter than through one lying substantially
horizontally with water flowing through due solely to gravity.
When hot soapy water is soaked into the filter paper while the
- 19
64~i~
filter is spinning, somewhat faster saturation i~ obtained and
it may also be that there ls more thorough saturation.
It will also be noted that inspection of the entire
filter paper is obtained both during the initial cleaning cycle
S and also during the rinsing cycle when aerated water is used for
both, so that the chances of overlooking a pin hole or tear
are significantly reduced. It should also be noted that in the
embodiment illustrated in Fig. 6, the inside nozzle 104 is
preferably arranged so as to be directed towards the front of the
apparatus to afford the fullest view by the machine operator.
By having the nozzles directed to different portions of the
filter membrane, it is also found tha~ other filter defects can
be detected. Thus, for example, if the filter has been used
;` where it can accumulate cement dust, it may become permanently `
plugged so that air cannot flow freely therethrough. This
conditin can be readily observed by merely noting the
quantity of water flowing through the filter from the nozzle 104
impinging on the inside. Since the nozzles on the inside and
outside are not directed towards each other, a substantial pres-
sure gradient is produced across the filter membrane and weakfilters that might rupture during use are detected since they
rupture during cleaning. It will be noted that a wet filter
during the washing operation i~ not as strong as the dry filter
~; actually put into service. Thus, it will be seen that during
the cleaning opertion, quick and reliable pressure, flow rate,
and leak inspection is obtained.
It will be apparent that if desired other arr~ngements
of cleaning nozzles for a bank of filter elements can be used,
such as groups of four, as may be best suited to a particular
cleaning operatlon. Manual insertion of the pair of nozzles is
- 20 - ~
~03646~
suitable or automatic arrangements may be employed. Many other
modifications and variations o~ the present in~ention can be
made by one skilled ~n the art. It is therefore to be under-
stood that within thè scope of the appended claim~ the in~ention
may be practiced other than as ~pecifically described.
~ 21
