GB1604834A

GB1604834A - Filtration of fluids

Info

Publication number: GB1604834A
Application number: GB2598/81A
Authority: GB
Original assignee: Fram Corp
Current assignee: Fram Corp
Priority date: 1978-05-31
Filing date: 1978-05-31
Publication date: 1981-12-16

Description

(54) FILTRATION OF FLUIDS (71) We, FRAM CORPORATION, a corporation organised and existing under the laws of the State of Delaware, United States of America, of 105 Pawtucket Avenue, East Providence, Rhode Island, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention relates to the filtration of fluids. More particularly, but by no means exclusively, the invention relates to oil filtration, for example in motor vehicles.

Replaceable filter elements of the "outside-in" flow type are well known and usually comprise a body of filter material retained in an annular cylindrical configuration by means of inner and outer cylindrical sleeves and axial end caps. The inner and outer sleeves are usually perforated. For oil filtration, the filter material will usually comprise a quantity of fibrous filter medium.

In one form of filter commonly encountered, and known as a filter of the "bowland-bolt" type, a replaceable filter element of the above described type is retained in proper location within a generally cylindrical filter casing having a closed bowl-shaped end by means of a retainer seat biased by a spring away from the bowl-shaped closed end which urges the filter element axially towards and against a filter mounting casting provided with inlet and outlet passages for flow of fluid to and from the filter. The filter casing is mounted to the filter mounting casting by means of a bolt which extends axially through the casing, retainer seat and filter element and into a female socket in the casting.

In an alternative arrangement which allows for oil filter element replacement in keeping with modern quick servicing techniques, the filter element is mounted within an interchangeable filter cartridge which has a generally cylindrical casing with a generally bowl-shaped closed end, the other end of the filter casing being partly closed by means of a plate extending thereacross and provided with a central threaded aperture which both provides an outlet for filtered oil from the cartridge and enables the cartridge to be threaded on to a co-operating filter mounting casting. Radially outwardly of the central opening the plate is provided with one or more further apertures which provide an inlet to the cartridge for oil to be filtered.

Whether the filter is of the bowl-and-bolt type or of the cartridge type, it is usually adapted for full-flow filtration. In other words, the entire fluid flow from inlet to outlet is caused to pass through the filter element. In so-called "parallel-flow" filtration, two filter elements, usually employing different filter material, are mounted, usually in axial alignment, within the same filter casing. The arrangement is such that at the commencement of use of the filter, the major part of the fluid flow is through one of the filter elements, the other element only passing a minor proportion of the fluid. As the first filter becomes clogged with dirt extracted from the fluid, an increasingly greater proportion of the fluid flow is caused to pass through the other filter. This parallel-flow arrangement is not considered very advantageous because in order for the pressure drop across the filter as a whole not to become unacceptably high in the second stage of utility of the filter, either the second filter element has to be such as to allow a substantial proportion of dirt to pass therethrough unfiltered, or alternatively, a by-pass valving arrangement has to be incorporated to ensure that a proportion of unfiltered fluid is enabled to by-pass the filter elements and to pass directly from inlet to outlet.

It has long been appreciated that a reduction in engine wear would result if a by-pass filter could be employed in addition to the normal full-flow filtration of engine oil, but until now there has been no entirely satisfactory way in which this could be conveniently accomplished. We have sought to devise embodiments of filter in convenient and practical forms capable of obtaining this advantage. As we shall explain, in our embodiments, in addition to the usual fullflow filtration, we abstract a proportion of the oil flow, filter it in a by-pass element and pass it directly to the sump. It should, however, be understood that the utility of our embodiments is not restricted to the filtration of oil.

In accordance with a first aspect of the present invention, there is provided interchangeable and replaceable filter means for a fluid filtering apparatus adapted to filter inflow fluid by generally outside-in flow through the filter means and to pass filtered fluid to two separate destinations, the filter means comprising: first and second filter elements of generally cylindrical external configuration each comprising filter material disposed between opposed axial end caps, one said element being received within the other with a radial space therebetween, and the filter means being further provided with means for receiving a generally tubular flow separation means forming part of or being connectable to a co-operating filter mounting of the filtering apparatus, and for co-operating with said flow separation means in use of the filtering apparatus to provide a first outflow path which includes the interior of said flow separation means for fluid which has been filtered by said one filter element to one said destination, a second outflow path to the other said destination for fluid which has been filtered by the other said element including the space radially intermediate the two said filter elements.

According to a second and alternative aspect of this invention, there is provided apparatus for filtering fluids comprising: a generally cylindrical outer casing; an end fitting at one axial end thereof, being coupled thereto, and providing an inlet for fluid to be filtered and separate outlets for passing filtered fluid to two separate destinations, and first and second filter elements of generally cylindrical external configurations each comprising filter material disposed between opposed axial end caps, the filter elements being mounted within said casing coaxially with the axis of the casing with one filter element received within the other and such that one said destination receives fluid which has been filtered by the first said filter element and such that the other said destination receives fluid which has been filtered by said second filter element.

In a third alternative aspect of this invention, we provide apparatus for filtering fluids consisting of an interchangeable and replaceable filter cartridge adapted for use with a filter mounting, and comprising: a generally cylindrical cartridge casing closed at one end, the other end of the cartridge casing being partly closed by means extending thereacross and being provided with a central opening, and with one or more further openings radially outwardly of said central opening and arranged to receive fluid to be filtered; means for receiving and locating within said central opening a spigot or like means of a filter mounting to which said cartridge is adapted to be mounted, whereby said central opening is adapted to provide respective outlets for fluid to two separate destinations; and first and second filter elements of generally cylindrical external configuration, each comprising filter material disposed between opposed axial end caps mounted within said cartridge casing coaxially with the axis of the cartridge casing with one filter element received within the other with a radial space therebetween and such that in operation one said destination is arranged to receive fluid filtered by the first said filter element and the other said destination is arranged to receive fluid filtered by the second said filter element.

This invention provides in a fourth alternative aspect thereof, apparatus of the bowland-bolt type for filtering fluids, comprising: a filter mounting provided with an inlet port for fluid to be filtered, and first and second outlet ports for passing filtered fluid to respective first and second destinations; a generally cylindrical casing open at one end, the other end being generally bowl-shaped and having a central aperture on the axial centre line of the casing but being otherwise closed; a bolt coupling the casing to the mounting, being received through said central aperture with its shank extending along said axial centre line and its shank end threadedly engaged in the mounting, the shank having at least one aperture in the side thereof communicating with a passage in said shank extending from said aperture and opening at said shank end into said mounting, and the mounting providing passage between said shank end and the second outlet port; and first and second annular filter elements of generally cylindrical external configuration, each comprising filter material disposed between opposed axial end caps, being mounted within the casing with one element received within the other with a radial space therebetween and with the bolt extending within the elements, its axis being aligned with the axes of the elements, such that in operation one said outlet port is arranged to receive fluid which has been filtered by the first said filter element and the other said outlet port is arranged to receive fluid which has been filtered by the second said filter element.

In one arrangement the radially inner filter element is caused to operate in parallel with the outer filter element (that is: it is caused to filter dirty fluid); while in an alternative arrangement the radially inner filter element is caused to operate in tandem with the outer filter element (that is: it receives a proportion of the fluid which has already been filtered by passage through the outer filter element and further filters that fluid before allowing it to pass to the appropriate destination).

When the invention is embodied in a filter of the bowl-and-bolt type, the bolt may be hollow and may provide a passage for fluid filtered by the radially inner filter element to pass to its respective destination. In the case of a quick-change filter cartridge, fluid flow from the radially inner filter element to its respective destination may be by a one piece moulding which acts both as a flow separator and as a locating means for the inner filter element within the cartridge, and is provided with a spigot seal which receives the distal end of a spigot fitted in the filter mounting casting and providing separation therein between the two outlet destinations. Descriptions of both these arrangements are given below.

Various other arrangements are possible within the general scope of this invention, and several such arrangements are also described in detail hereinafter.

The invention is hereinafter more particularly described by way of example only with reference to the accompanying drawings, in which: Fig. 1 shows an embodiment of filter in accordance with the present invention and of the quick-change cartridge type, partly in section; Fig. 2 shows an axial sectional view of one half of an embodiment of filter of the bowland-bolt type in accordance with the invention, the other half being similar; and Fig. 3 shows a further embodiment of bowl-and-bolt filter in accordance with this invention in axial section.

The cartridge generally indicated 1 in Fig.

1 comprises a generally cylindrical casing 2 having a bowl-shaped closed end 3, and the other end of the casing being partially closed by means of a plate 4 having a series of apertures 5 providing inlets to the filter cartridge and a central threaded female aperture 6. Alternatively, an externally or male threaded spigot (not illustrated) may be provided in place of the central threaded aperture, for reception in a threaded socket.

Mounted within the casing are radially outer and radially inner filter elements 7 and 8.

The two filter elements 7, 8 are generally cylindrical in configuration, having their respective filter media 7a, 8a disposed between opposed axial end caps 7b, 7c and 8b, 8c respectively. Filter medium 7a may consist of a body of fibrous filter medium or of a pleated paper annulus in accordance with the usual practice in this art.

The co-operating filter mounting casting 11 has an inlet passage 12 and first and second outlet passages 13 and 14 respectively. The inlet passage 12 and the first outlet passage 13 would be coupled into the engine oil circuit in the usual way, whereas the second outlet passage would in use be coupled directly to the sump. In order to couple the cartridge 1 to the filter mounting casting 11, an externally threaded tube section 15 is provided in this.embodiment, as shown, and a spigot 16 is fitted in the filter mounting casting 11. The cartridge 1 is provided in conventional fashion with a sealing ring 18 mounted in a metal locating ring 19 which is attached to the plate 4, as by welding, and folded into a seam with the.

adjacent edge of the casing 2.

The second or radially inner filter element is centrally disposed within the space available on the internal or clean side of the filter element and comprises a body 8a of fibrous filter material packed within a capsule 41 which in this illustrated arrangement is conveniently formed of plastics material and has a generally cylindrical external configuration. Filter element 8 has opposed axial end caps 8b and 8c respectively located by a shoulder 42 and an internal edge portion 43 of capsule 41. Capsule 41 has an integral flange 44 enabling it to be located and firmly held between end cap 7c of filter element 7 and a retainer spring 10. In order to allow for location of spigot 16, the capsule 41 is provided in the illustrated arrangement with an integral frustoconical extension piece 45 provided with a spigot seal 46. Alternatively, the seal may be formed on the spigot, or, if the spigot is of greater axial extent, within capsule 41. The cartridge may be provided with a cartridge relief valve assembly, such as that shown at 47. The illustrated relief valve assembly has a housing in two parts 48 and 49, each formed of plastics which are a snapfit together, flange 50 of housing part 48, together with the outer circumferential edge portion 51 of annular valve member 52 fitting into annular groove 53 of housing part 49. A compression spring 54 mounted within housing part 48 via an annular spring plate 55 biases the annular valve member 52 against its seat on the confronting end portion of housing part 49. When the differential pressure across the filter becomes sufficiently large annular valve member 52 will be forced from its seat to allow unfiltered fluid from inlet apertures 5 directly to the space between tube section 15 and spigot 16.

An antidrain valve member 56 is also shown in Fig. 5, its inner annular edge being trapped between housing part 49 and end cap 7b of filter element 7.

Fluid filtered by passage through full-flow filter element 7 passes through openings 57 in relief valve housing part 49 and thence to an outlet, which in engine oil filtration would be coupled in to the engine oil circuit, via the space between tube section 15 and spigot 16.

When filter element 8 is to operate in true parallel fashion, its end cap 8e is perforated so that a proportion of the dirty fluid is filtered as it passes through filter medium 8a before passing out through perforations 58 in the other end cap 8b in to the interior of frusto-conical extension piece 45 and thence to its destination (such as the sump in engine oil filtration) by passage along the interior of spigot 16. In the partial tandem flow variant, cylindrical side wall 59 of capsule 41 is perforated instead of end cap 8c so that a portion of the fluid already filtered by passage through filter element 7 is further filtered in element 8 before discharge into the interior of frusto-conical extension piece 45 as before. A restrictor may be required on the outlet side of element 8. A suitable restrictor is shown mounted at 60 in the interior of spigot 16. Alternatively the restrictor may be provided by a suitably sized hole at the centre of a restrictor plate (as shown in dotted lines at 60a) mounted within capsule 41.

All parts in the bowl-and-bolt filter of Fig.

2 which are generally similar in construction and/or operation to similar parts of the embodiment of Fig. 1 are shown with the same reference numeral as in Fig. 1 but increased by 100 so that, for example, filter element 107 of Fig. 2 is equivalent to filter element 7 of Fig. 1. The main difference between the two arrangements is that in the embodiment of Fig. 2 the shank, here indicated 32, of bolt 33 is formed as a tube or otherwise provided with an axial passage for receiving fluid filtered by the second or radially inner filter element 108 and with apertures 34. The distal end of bolt 33 opens out into a passage 35 which provides the second outlet passage in filter mounting casting 111 of this embodiment. Operation of the filter of Fig. 2 is otherwise the same as for the embodiment of Fig. 1. As before, the second or inner filter element 108 of Fig. 2 may operate truly in parallel with first filter element 107 or in tandem with the first filter element so far as the by-pass flow is concerned depending upon whether the external cylindrical shell 22 of filter element 108 or the end cap 1 08b is perforated.

In Fig. 2, the second filter element 108 is mounted coaxially within first filter element 107. The opposed axial end caps 108b and 108c of filter element 108 form part of a plastics housing or capsule 61. Fluid to be filtered by element 108 in the true parallel flow variant passes into the filter element via perforations 62 in end cap 108c; and in the partial tandem flow variant via perforations 62a in external cylindrical shell 22. Filtered fluid passes out of element 108 via perforations 63 on its inner cylindrical shell and thereafter via perforations 34 into the interior of bolt 33. A frusto-conical extension piece 64 joined to or integral with housing or capsule 61 with a seal 65 at its inner periphery co-operating with bolt 33 separates the fluid at the outlet side of filter elements 107, 108, for passage to the respective destinations. As illustrated in Fig. 2, the element 108 tapers slightly from one axial end to the other but still has a configuration which is generally cylindrical.

We have described above one arrangement of the quick-change cartridge type (Fig.

1) and one of the "bowl-and-bolt" type (Fig.

2), in each of which both filter elements are accommodated in the axial space which would normally be required for the equivalent full-flow filter itself. Clearly this is of great importance for engine compartments in which space is at a premium and arrangements such as those described in our copending applications 24888/78 (Serial No.

1604833) from which the present application has been divided and which is itself divided from our application 7705/77, 24887/78 (Serial No. 1604832) also divided from 7705/77, and 7705/77 (Serial No. 1604831) itself, which require an additional axial extent of filter, cannot be employed.

We consider the arrangement of Fig. 3 to be particularly advantageous since it provides these advantages without greatly adding to the difficulties of fabrication. The filter of Fig. 3 is of the bowl-and-bolt type. The reference numerals used correspond in general to those used in Fig. 2, but with the addition of 100. Thus, filter element 207 of Fig. 3 is generally equivalent to element 107 of Fig. 2. The filter means of Fig. 3 is of generally cylindrical external configuration and has a one-piece outer cylindrical sleeve 66, being the outer perforated sleeve of element 207. A portion of the fluid filtered by element 207 passes through apertures 67 in a plate 68 (which is suitable formed integrally with end cap 207b) and which carries an annular sealing rim 69 which seals incoming fluid in passage 212 from outgoing fluid in passage 213 which has been filtered by element 207. The other end of element 207 is supported on an end locating plate 70 via an intermediate sealing ring 71 which is carried by a plate 28 which corresponds to plate 68 at the opposite axial end of element 207 and is suitably formed integrally with end cap 207c.

The end locating plate 70 is biased away from the closed bowl end by the compression spring provided about the bolt. Part of the fluid already filtered by element 207 is further filtered in element 208 (also by outside-in flow) and then passes via aperture 134 into the interior of shank 132 of bolt 133 and thence to outlet passage 135. The end caps 208b and 208c of element 208 each carry a seal 72. It will be noted that element 208 is not fixed to any other parts but is freely slidingly received on shank 132 via its seals 72. This greatly aids fabrication since element 208 does not require precise location, but may simply be inserted within the central axial space of element 207 during assembly of the parts. The elements 207 and 208 together with plates 28 and 68 form a unitary replacement filter cartridge for the bowl-andbolt filtering apparatus of Fig. 3.

The arrangement of Fig. 3 thus derives doubled advantage for ease and convenience in fabrication and use. One filter element is coaxially located within the other providing the advantage of reduced overall axial extent of the filter. This allows this filter to be employed in the space where a conventional full flow filter would otherwise have been used. The two elements are axially aligned and formed into a unitary replacement filter media cartridge, and we obtain the advantage of ease of assembly--only one part rather than two needs to be incorporated into the filter during fabrication or assembly.

There is less likelihood of mistakes in assembly-as by inserting separate elements into the filter casing possibly inverted or in the wrong order. Additionally this construction makes for ease of servicing of bowl-and-bolt filters.

WHAT WE CLAIM IS: 1. Interchangeable and replaceable filter means for a fluid filtering apparatus adapted to filter inflow fluid by generally outside-in flow through the filter means and to pass filtered fluid to two separate destinations, the filter means comprising: first and second filter elements of generally cylindrical external configuration each comprising filter material disposed between opposed axial end caps, one said element being received within the other with a radial space therebetween, and the filter means being further provided with means for receiving a generally tubular flow separation means forming part of or being connectable to a co-operating filter mounting of the filtering apparatus, and for co-operating with said flow separation means in use of the filtering apparatus to provide a first outflow path which includes the interior of said flow separation means for fluid which has been filtered by said one filter element to one said destination, a second outflow path to the other said destination for fluid which has been filtered by the other said element including the space radially intermediate the two said filter elements.

2. Interchangeable and replaceable filter means according to Claim 1 in the form of an interchangeable and replaceable filter cartridge adapted for use with a filter mounting and comprising a generally cylindrical cartridge casing closed at one end, the other end of the cartridge casing being partly closed by means extending thereacross and being provided with a central opening and with one or more further openings radially outwardly of said central opening and arranged to receive fluid to be filtered; said filter elements being mounted within said cartridge casing.

3. Interchangeable and replaceable filter means according to Claim 1 in the form of a replacement cartridge for a fluid filtering apparatus of the bowl-and-bolt type which comprises: a filter mounting provided with an inlet port for fluid to be filtered, and first and second outlet ports for passing filtered fluid to respective first and second destinations; a generally cylindrical casing open at one end, the other end being generally bowl-.

shaped and having a central aperture on the axial centre line of the casing but being otherwise closed; and a bolt coupling the casing to the mounting, being received through said central aperture with its shank extending along said axial centre line and its shank end threadedly engaged in the mounting, the shank having at least one aperture in the side thereof communicating with a passage in said shank extending from said aperture and opening at said shank end into said mounting, and the mounting provided passage between said shank end and the second outlet port; and wherein said replacement cartridge is adapted to be mounted within said casing with the axes of said filter elements coincident with the axis of said bolt, which bolt is adapted to function as said generally tubular flow separation means.

4. Interchangeable and replaceable filter means according to Claim 3, wherein the said one filter element is arranged to operate in tandem with the said other, the said one filter element being arranged to receive and filter a portion only of the fluid already filtered by the said other filter element, the remainder of the fluid filtered by the said other filter element being arranged in use to pass to the said other destination, while the fluid filtered by the said one filter element is arranged to pass to the said one destination; and wherein the said one filter element is freely slidingly located radially within the other said element and is of shorter axial extent than the other said element.

5. Apparatus for filtering fluids comprising: a generally cylindrical outer casing; an end fitting at one axial end thereof, being coupled thereto, and providing an inlet for fluid to be filtered and separate outlets for passing filtered fluid to two separate destinations, and first and second filter elements of generally cylindrical external configuration each comprising filter material disposed between opposed axial end caps, the filter elements being mounted within said casing coaxially with the axis of the casing with one filter element received within the other with a radial space therebetween and such that one said destination receives fluid which has been filtered by the first said filter element and such that the other said destination receives fluid which has been filtered by said second filter element.

6. Apparatus for filtering fluids consist

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. of the parts. The elements 207 and 208 together with plates 28 and 68 form a unitary replacement filter cartridge for the bowl-andbolt filtering apparatus of Fig. 3. The arrangement of Fig. 3 thus derives doubled advantage for ease and convenience in fabrication and use. One filter element is coaxially located within the other providing the advantage of reduced overall axial extent of the filter. This allows this filter to be employed in the space where a conventional full flow filter would otherwise have been used. The two elements are axially aligned and formed into a unitary replacement filter media cartridge, and we obtain the advantage of ease of assembly--only one part rather than two needs to be incorporated into the filter during fabrication or assembly. There is less likelihood of mistakes in assembly-as by inserting separate elements into the filter casing possibly inverted or in the wrong order. Additionally this construction makes for ease of servicing of bowl-and-bolt filters. WHAT WE CLAIM IS:

1. Interchangeable and replaceable filter means for a fluid filtering apparatus adapted to filter inflow fluid by generally outside-in flow through the filter means and to pass filtered fluid to two separate destinations, the filter means comprising: first and second filter elements of generally cylindrical external configuration each comprising filter material disposed between opposed axial end caps, one said element being received within the other with a radial space therebetween, and the filter means being further provided with means for receiving a generally tubular flow separation means forming part of or being connectable to a co-operating filter mounting of the filtering apparatus, and for co-operating with said flow separation means in use of the filtering apparatus to provide a first outflow path which includes the interior of said flow separation means for fluid which has been filtered by said one filter element to one said destination, a second outflow path to the other said destination for fluid which has been filtered by the other said element including the space radially intermediate the two said filter elements.

6. Apparatus for filtering fluids consist

ing of an interchangeable and replaceable filter cartridge adapted for use with a filter mounting, and comprising: a generally cylindrical cartridge casing closed at one end, the other end of the cartridge casing being partly closed by means extending thereacross and being provided with a central opening, and with one or more further openings radially outwardly of said central opening and arranged to receive fluid to be filtered; means for receiving and locating within said central opening a spigot or like means of a filter mounting to which said cartridge is adapted to be mounted, whereby said central opening is adapted to provide respective outlets for fluid to two separate destinations; and first and second filter elements of generally cylindrical external configuration, each comprising filter material disposed between opposed axial end caps mounted within said cartridge casing coaxially with the axis of the cartridge casing with one filter element received within the other with a radial space therebetween and such that in operation one said destination is arranged to receive fluid filtered by the first said filter element and the other said destination is arranged to receive fluid filtered by the second said filter element.

7. Apparatus of the bowl-and-bolt type for filtering fluids, comprising: a filter mounting provided with an inlet port for fluid to be filtered, and first and second outlet ports for passing filtered fluid to respective first and second destinations; a generally cylindrical casing open at one end, the other end being generally bowl-shaped and having a central aperture on the axial centre line of the casing but being otherwise closed; a bolt coupling the casing to the mounting, being received through said central aperture with its shank extending along said axial centre line and its shank end threadedly engaged in the mounting, the shank having at least one aperture in the side thereof communicating with a passage in said shank extending from said aperture and opening at said shank end into said mounting, and the mounting providing passage between said shank end and the second outlet port; and first and second annular filter elements of generally cylindrical external configuration, each comprising filter material disposed between opposed axial end caps, being mounted within the casing with one element received within the other with a radial space therebetween and with the bolt extending within the elements, its axis being aligned with the axes of the elements, such that in operation one said outlet port is arranged to receive fluid which has been filtered by the first said filter element and the other said outlet port is arranged to receive fluid which has been filtered by the second said filter element.

8. Apparatus according to any of Claims 5, 6 or 7, wherein the second filter element is arranged to operate in parallel with the first, each filter element receiving a portion of the incoming unfiltered fluid and separately filtering the respective fluid portion which is then arranged to pass to its respective destination.

9. Apparatus according to any of Claims 5, 6 or 7, wherein one of the said filter elements is arranged to operate in tandem with the other, the said other filter element being arranged to receive and filter a portion only of fluid already filtered by the said one filter element, the remainder of the fluid filtered by the said one filter element being arranged to pass to one of the said destinations, while the fluid filtered by the said other filter element is arranged to pass to the said other destination.