AU738016B2 - A filter cartridge and method - Google Patents

Description

P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name of Applicant: Actual Inventor(s): Address for Service: Invention Title: Details of Original Application(s) No(s): FILTER TECHNOLOGY AUSTRALIA PTY LTD Paul Charles Lindberg Kenneth Gordon Mortensen

INTELLPRO

Patent Trade Mark Attorneys Level 7, Reserve Bank Building 102 Adelaide Street BRISBANE, QLD, 4000 (GPO Box 1339, BRISBANE, 4001) A FILTER CARTRIDGE AND METHOD Australian Patent Application No. 76855/96 filed 28 November 1996.

The following statement is a full description of this invention, including the best method of performing it known to me: "A FILTER CARTRIDGE AND METHOD" TECHNICAL FIELD OF THE INVENTION THIS INVENTION relates to a filter cartridge and in particular but not limited to a recyclable filter cartridge manufactured from reinforced plastic material using a moulding technique.

BACKGROUND ART Present methods of on board fuel or oil filtration involve environmentally unfriendly disposal of saturated filter elements.

In one prior art method, filtration of fuel or oil on board a vehicle involves 10 the use of a flexible filter media housed within a disposable metal can. In order to exchange a spent filter the user simply replaces the whole can so that the can and filter media are disposed of together.

0:90 In another prior art method the can is not employed and the flexible filter element is placed directly into a fixed permanent housing on the vehicle. This 15 second method is more preferable from an environmental point of view as the contaminated flexible filter element is the only part disposed of but the means of disposal is not altogether clear as it is disposed of by the end user in an oo.: uncontrolled way. On the other hand this method is less user friendly as the oily element must be removed and in addition the replacement filter element can be 0:000 20 incorrectly installed thereby reducing filter efficiency.

As effective filtration is achieved by making sure the filtrant properly passes through the filter the disposable metal can method is more efficient as the filter element can be placed very tightly within the can under controlled manufacturing conditions. Due to the controlled manufacturing conditions there is little risk of incorrect installation as the geometry of the can and the housing in which the can fits is defined.

Another problem with existing filters is that [the filter element tends to break down due to small amounts of water being present. Small parts of the filter media are prone to flow out with the filtrate and can clog apparatus downstream of the filter. Also] the filter media to date has not been purpose made with paper rolls usually made for other purposes such as toilet rolls being used. This means the efficiency of filtration has not been optimised.

Another problem arises with the existing can type cartridge insofar as the can is an assembly of parts and a reduction in the number and an improvement in durability of the parts would be desirable.

Present manufacturing techniques involve the insertion of the filter element into the can. The filter element is compressed and upon the application of a press forced into the can. This causes distortion of the filter element in order to obtain the tight fit within the can.

10 It is an object of the present invention to provide a filter cartridge which S* alleviates at least to some degree one or more of the above mentioned deficiencies of the prior art in relation to ensuring efficient filtration by improving the filter .media.

It is another object of the present invention to provide a filter element that 15 provides an improved filtration efficiency.

It is a further object of the present invention to provide a filter cartridge that provides a useful alternative to the prior art.

~OUTLINE OF THE INVENTION In one aspect the present invention resides in a filter element for a S 20 filter. The filter element includes a centre tube and at least on filter medium disposed about the tube. The filter medium is of a grade that allows the filter medium to be machine wound tightly onto the tube without tearing. In this manner the wound filter medium achieves a higher density that the prior art filter elements.

The higher density is one reason for improved filtration efficiency.

The filter medium may be a non biodegradable material. Preferably the non biodegradable material of each filter medium is a facial quality tissue paper. More preferably the tissue paper is made from virgin pulp. As virgin pulp has not been treated with colouring the problem of colour contamination in oil is avoided.

The tissue paper may be selected from a range of grades depending on required softness and thickness. The applicant has found that paper softness is a contributing factor to filter efficiency. The reason is that contaminants in oil or fuel stick to softer tissue better. Filters with softer tissues as filter media will therefore retain or trap more contaminants and give a more efficient cleaning effect. In addition softer tissues allow more layers of the tissues in a given space than harder tissues. This quality also improves the cleaning effect. Where the tissue paper for each filter element is to be machine wound the paper tissue must be able to withstand the tension during winding and thereby allows the filter medium to be tightly wound without tearing. The applicant has found that paper rated at about 17 grams per square meter (GSM) is suitable as it can be wound sufficiently tightly without tearing.

10 Tissue paper supplied by Carter Holt Harvey and having a product code number of 5799 10/20 2 ply is most suitable for the filter medium as it is nondegradable, made of virgin pulp and rated at 17 GSM.

Each filter medium may be wound onto the centre tube to a roll form.

Advantageously the filter medium has one of its ends adhered to the centre tube by 15 an adhesive means. The adhesive means is preferably inert to the lubricant or fuel.

An example of the adhesive means suitable for the filter element of the present invention is manufactured by 3M and is identified by 3M Scotch ECR1675. The 3M adhesive does not froth in the presence of oil of fuel.

Using the 17 GSM tissue paper the centre tube onto which the paper is S 20 wound can be reduced from 38mm diameter as in the existing toilet rolls to a diameter of 25mm and its length increased from 90mm long in the existing toilet rolls to 170mm long in the wound roll, while maintaining the same external diameter of the toilet rolls used in the existing filter elements, that being 110mm.

This arrangement of the filter medium of the present invention allows between 43m to 46m of the tissue paper to be rolled and employed per filter element forming an annular roll about 30mm-35mm wide. The arrangement thereby reduces the size of the existing toilet rolls, translating this density measure to an average length of paper per centimeter width being between a minimum of about 12 meter per cm radial width and a maximum of about 15 meter per cm radial width. The length of paper per cm radial width of annular rolls varies in accordance to tightness of the rolls.

The standard roll size commonly employed is 110mm in diameter including the central core. In order to form paper rolls with 110mm external diameter and diameter centre tube the radial width of the annular roll is increased to 42.5mm compared to the 30mm-35mm size referred to above. Using the same tissue paper and the same roll tightness as described above the length of paper for the 110mm roll must be longer than that of 43m to 46m for the annular roll with 30mm-35mm width for increasing the roll width by 7.5mm-12.5mm to 42.5mm.

As mentioned above the length of paper for forming the 110mm rolls depends on winding tightness and therefor the cleaning efficiency required for the rolls.

S 10 At densities below about 12m per radial cm the media has a tendency to collapse whereas at the higher end of the range in excess of about 15m per radial cm the flow reduces noticeably.

SoPreferably the inside surface of the side wall of the cartridge is ribbed or otherwise profiled to deter tracking of the feedstock, between the side wall and the 15 or each filter element.

The cartridge may have a single inlet at its open end for lubricant or oil to 'enter the cartridge. Alternatively the cartridge may have respective inlets at opposite ends and a shared transverse wall intermediate the opposite ends thus forming back-to-back filters.

S 20 Where inlets are provided at both ends of the cartridge the centre tube and the cross flow passages may be arranged between adjacent filter elements on opposite sides of the shared wall.

The filter cartridge is preferably recycled but may be discarded along with the filter element once the or each filter element becomes fully charged with trapped and retained solids.

In a further aspect, the present invention resides in a filter housing for filtering a feedstock including: a body or housing; an inlet in the housing to allow a supply of feedstock to be filtered from the housing; an outlet in the housing to allow flow of filtered feedstock or filtrate from the housing; a hollow centre post disposed coaxially within the housing, the wall of the centre post having fluid communication ports between the outside and the bore thereof, the bore being connected to the housing outlet; a filter cartridge as herein described and being within the housing; and filter cartridge installation means providing releasably sealable installation means providing releasable sealable installation of the filter cartridge in the housing whereby the feedstock flows from the inlet to the outlet through the filter cartridge.

Oo: 10 Preferably, the housing is closed at its base and open at its top, the top being closed by a cap fitted with sealing means to engage the wall of the housing.

Preferably, the housing inlet and the housing outlet are at the base of the °housing as is a drain port to enable contaminated feedstock to be drained from the bottom of the housing.

15 Preferably, the open end (ie. inlet) of the (or uppermost) filter cartridge is adjacent the top of the housing so that the feedstock flows from the housing inlet •o upwardly through an annular passage defined by the wall of the housing and the cartridge.

Preferably, a hollow centre post is disposed within, and sealably connected 20 to, the centre tube.

Preferably, sealing means seal against flow of fluid between the housing and the centre tube, so arranged that filtrate in the centre tube flows through the fluid communication ports into the bore of the centre post, and then to the housing outlet.

Preferably, a filter medium retaining ring is provided about the upper end of the centre tube and bears against the top of the filter medium. A compression spring, about the centre post, is preferably interposed between the housing cap and the retaining ring to urge the retaining ring into engagement with the filter element to seal the upper end of the centre tube and to retain the filter medium in the cartridge.

Preferably, a pressure knob, screw-threadably mounted on the centre post, bears against the closed end of the cartridge to urge the filter cartridge upwardly against the compression spring.

Preferably, respective seal means seal the centre post to the coaxial hole through the retaining ring and the second end of the cartridge.

The filter element, is preferably a roll of facial-quality paper tissue of standard size. However, other non biodegradable filter media may be used, such as, but not limited to, non biodegradable cotton, hemp, artificial or synthetic fibres, or any suitable porous or foraminous material.

The housing, cartridge, centre tube, centre post, lid and other hardware are *preferably made from reusable polymeric, ceramic or composite compounds and the like suitable for being recycled.

Preferably, the seals are of an oil resistant elastomer. However, permanently deformed or rigid sealing material may also be used.

15 BRIEF DESCRIPTION OF THE DRAWINGS order that the present invention can be more readily understood and be put into practical effect reference will now be made to the accompanying drawings oooo which illustrate preferred embodiments of the invention and wherein:- Figure 1 is a flow diagram illustrating a preferred example of the method of S 20 recycling according to the present invention; Figure 2 is a perspective view of a typical filter assembly; Figure 3 is a section through a typical filter assembly; Figure 4 is a section through another embodiment of the present invention; Figure 5 is a section illustrating a typical end wall; Figure 6 is a section illustrating a further embodiment of a centre tube suitable for use with a filter assembly according to the present invention.

METHOD OF PERFORMANCE The following description relates to the preferred use of an improved cartridge used as a recyclable cartridge but it will be appreciated that the cartridge could be used as a disposable cartridge.

8 Referring to the drawings and initially to Figure 1 there is illustrated in schematic form the recycling method according to the present invention and a preferred tool utilised with that recycling method.

As can be seen in the upper left hand corner of the flow diagram a cartridge is made according to the teachings of the present invention and in this case formed from a moulded carbon fibre reinforced plastics material so that the cartridge is sufficiently ridged so that it can be reused. The cartridge is injection moulded using a formulation of 60% by weight nylon melt resin with chopped glass fibre to by weight. The resin has a melt temperature in excess of 200C.

e 10 At 11 a filterelement is prepared and this involves a 100% cellulose element 12 into which a reusable moulded or otherwise formed reinforced carbon fibre centre core 13 is pushed. The filter element and core 13 are forced using a press a.

either together or in turn into the cartridge The filter element 11 is in the form of a roll and has an external diameter of o:oa,, 15 about 110Omm. The core 13 is sized at about 25mm diameter. The cellulose element 12 is machine wound onto the core 13 to provide an average filtration density in the range of about 12 to 15 meters of paper element per cm radial width of the roll.

Now the cartridge 10 in the illustrated embodiment includes anannular flare at 14 which operates as a filter element lead-in guide and assists in feeding the filter element into the cartridge.

The end wall 15 of the cartridge illustrated includes projections to be described further below and the side walls include spaced annular ridges. The projections serve to keep the filter element away from the end wall 15 so that filtrate can track across the end wall 15 into the centre core 13. The annular ridges are used to inhibit tracking of filtrant between the filter element and the wal Is of the cartridge.

Once the filter element and cartridge are assembled then a centre tube shown at 17 is pushed into the assembly. The centre tube in this case includes sealing means in the form of an o-ring at 18 which seals against the core 13 to NJRA inhibit tracking of filtrant between the centre tube 17 and the core 13.

The filter cartridge is then placed in position inside a filter housing to be described as follows.

The housing can be on say a truck depicted schematically at 19 and once the filter element 11 is spent the whole cartridge is returned from the vehicle 1 9 to the factory for recycling. The central tube 17 is withdrawn and then a suitable tool shown schematically in Figure 1 is used to extract the spent filter element 11 from the cartridge.

As can be seen the tool 20 includes a claw assembly 21 utilising a manually operable expander 22 so that upon insertion of the claw assembly 21 into the filter e e 10 element 11 the expander 22 can be employed to move the jaws 23 of the claw assembly to the position illustrated at 24. A lever 25 is used to extract the claw assembly 21 and thereby the filter element 11 from the cartridge 10. It will be appreciated once the spent filter element has been removed from the cartridge the cartridge can be reloaded and it can be returned and reused over and over again.

15 Figures 2 and 3 illustrate how the filter cartridge 10 and its associated .element are used in a filter housing while Figure 4 illustrates an alternative embodiment where the filter cartridge in this case 26 is effectively back-to-back 0000 filter assemblies 10 where the filter elements are half size and a central wall having °io• back-to-back grids is formed at 27. The cres and central tubes are all half sized as °O6OO well and in effect the cartridge illustrated in Figure 4 is back-to-back cartridges This particular cartridge is reused in a similar fashion to the cartridge described earlier and recycled in the same general way. The cartridge of Figure 3 due to its greater capacity is typically used for oil filtering application while the cartridge of the Figure 4 is used for fuel filtration.

A typical end wall of each of the cartridges, illustrated in Figures 3 and 4 is shown in Figure 5 while the end of a preferred central tube having flow through passages at 28 is illustrated in Figure 6.

Whilst the above has been given by way of illustrative example of the present invention, many variations and modifications thereto will be apparent to those skilled in the art without departing from the broad ambit and scope of the invention as set forth in the appended claims.

Claims (23)

1. An oil filter cartridge for an engine oil filter, the cartridge includes a filter element having a centre tube and at least one filter medium disposed about the tube, wherein the filter medium is a paper of a grade that allows the filter medium to be machine wound tightly onto the tube in a roll without tearing, the tightness of the winding being chosen above a lower tightness level at which the roll has a tendency to collapse over time while in use and a high tightness level where the flow of oil through the roll tends to decrease noticeably.

2. The cartridge according to claim 1 wherein the cartridge is open at each end and the lower tightness level gives rise to a paper density of not less than about 12m/radial cm.

3. The cartridge according to claim 1 or claim 2 wherein the cartridge is open at each end and the higher tightness level gives rise to a paper density of not greater than about 15m/radial cm. S 15

4. The cartridge according to any one of claims 1 to 3 wherein the filter medium being made of a material which remains substantially intact in the presence of water contamination in oil or fuel.

5. The cartridge according to any one of claims 1 to 4 wherein the filter medium is substantially non biodegradable. S: 20

6. The cartridge according to any one of claims 1 to 5 wherein the filter medium is a facial quality tissue paper.

7. The cartridge according to claim 6 wherein the tissue paper is made from virgin pulp.

8. The cartridge according to claim 7 wherein the filter element is in the form of a tightly wound paper roll, machine wound using the virgin pulp paper of suitable strength for machine winding.

9. The cartridge according to claim 8 wherein the tissue paper is adhered to the roll by an inert adhesive.

The cartridge according to one of claims 6 to 9 wherein the element is wound from 43m to 46m of paper. 11

11. The element according to any one of claims 6 to 10 wherein the tissue paper is selected from a range of grades depending on required softness and thickness.

12. The cartridge according to any one of claims 6 to 11 wherein the tissue paper is rated at about and not less than 17 grams per square meter (GSM).

13. The cartridge according to any one of claims 1 to 12 wherein the filter medium is wound onto the centre tube in a roll form and has one of its ends adhered to the centre tube by an adhesive means which is inert to lubricant and/or fuel.

14. The cartridge according to any one of claims 1 to 13 including:- a hollow filter canister having an open end forming an inlet for the filter, a side wall and a second end opposite to the open end of the canister; one or more said filter element arranged within the canister so that: a feedstock to be filtered passes through the inlet to the one or more filter element, and the filtered feedstock passes through a cross flow passage into the centre tube defining an outflow passage; the one or more filter element is wound onto the center tube in sealing engagement with the centre tube and the side wall of the canister; and the feedstock passes substantially axially through the one or more filter element to the cross flow passage. 20

15. The cartridge according to claim 14 wherein the inside surface of the side wall of the canister being ribbed or otherwise profiled to deter tracking of contaminants removed from the feedstock, between the side wall and the one or more filter element.

16. The cartridge according to claim 14 or 15 wherein the cross flow passage is filled with a material with a high transverse porosity.

17. The cartridge according to claim 16 wherein the high porosity material including woven gauze and/or a moulded grid.

18. The cartridge according to one of claims 14 to 17 wherein the canister includes an end wall opposite to said open end, the end wall having a plurality of circumferentially spaced deformations projecting partly into the cross flow passage ,T Rthereby dividing the cross flow passage into a primary flow passage which is above 12 the deformation and secondary flow passages between respective adjacent deformations.

19. The cartridge according to claim 18 wherein the woven gauze and/or the moulded grid is located in the primary flow passage.

20. The cartridge according to any one of claims 14 to 19 wherein the or each filter element having two or more filter media which are stacked together.

21. The cartridge according to any one of claims 14 to 20 wherein the cartridge is adapted to receive the or each filter element under compression to form a tight fit between the cartridge and the or each element, the cartridge being hollow and having a side wall that is sufficiently rigid for multiple use involving repeated -'insertion and removal of filter elements from the cartridge.

S•22. The cartridge according to claim 21 wherein the cartridge is of an integral one piece construction, the side wall having an inside surface and there being an inner transverse wall, the inner wall including a filter element support grid allowing flow of filtrate across the inner wall of the cartridge through the support grid while at the same time providing fairly uniform support for the or each filter element across the inner transverse wall of the cartridge.

23. The cartridge according to claim 22 wherein the cartridge has respective inlets at opposite ends and a shared transverse wall intermediate the opposite ends 20 thus forming back-to-back filters. DATED this 16'h day of July 2001 FILTER TECHNOLOGY AUSTRALIA PTY LIMITED By their Patent Attorneys INTELLPRO