CA1036461A - Apparatus for cleaning air filters - Google Patents

Abstract

APPARATUS FOR
CLEANING AIR FILTERS

Abstract of the Disclosure Apparatus is described for washing hollow cylindrical engine air cleaners or filter elements. Cleaning and pressure, flow, and leak testing are all performed by successive soaping, rinsing, and pressure testing with aerated water. An aerated flow of water onto the filter membrane forces water through a sound membrane, and a mixture of water and air bubbles through a membrane with a tear or hole to provide a leak test. An inexpensive aerating nozzle is provided. A spray tube inside the filter washes off dirt and aspirates air for leak checking. The tube is movable along the length of the filter for best cleaning.

Description

~(~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 ~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 ; ~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 . .

, .
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 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.

~ ;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 !
~ .

, ' 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 . ` ~' , . . . .

~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 .

. 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 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~.

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 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 ~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 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.

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Claims (5)

I CLAIM

1. 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 surface dirt therefrom and for pressurizing the partially closed inside 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.

2. An apparatus as recited in claim 1 wherein the means for moving a source of water comprises nozzle means for impinging water on a face of the filter membrane at an angle from a normal to the filter membrane surface.

3. Apparatus as recited in either claim 1 or claim 2 for cleaning a filter comprising a cylindrical member having pleats extending along its length wherein the means for moving a source of water comprises nozzle means for discharging a fan-shaped spray of water, the axis of the fan being along the axis of the filter.

4. 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.

5. Apparatus as recited in claim 3 wherein the nozzle means comprises means for generating a fan-shaped flow of water and impinging opposite sides of the fan-shaped flow against opposite portions of the inside of the filter membrane.