Fuel filter key system

Abstract: A key system for a fuel filter assembly employs angularly spaced arcuate protrusions (100a,100b,100c...) which protrude radially from the cylindrical sidewall of the cartridge (14). The base (12) has corresponding tracks (110a,110b,110c...) defined by equidistantly spaced rails which engage with the protrusions (100a,100b,100c...) to key the cartridge with the base. The key system is employed either apart from or in conjunction with a second axial key/slot system of the base (12) and the cartridge (14).

Description: This invention relates generally to fuel filters employed in connection with internal combustion engines. More particularly, the present invention relates to fuel filters having a replaceable cartridge for removing foreign particles and/or separating water from the fuel supply system of an internal combustion engine. Conventionally, fuel filters employ a disposable filter cartridge which is replaced at pre-established intervals of filter usage. In practice, the filter cartridge requirements may vary depending upon such characteristics as the type and make of the internal combustion engine, the specific application for which the engine is employed, the climate in which the combustion engine is operated, and/or regional characteristics as to the quality of the fuel supply. The filter cartridges which are suitable for replacement, thus commonly vary as to axial dimensions, capacity and filter media qualities. One of the recurring problems in assuring quality fuel filter performance is encountered in connection with replacement of the fuel cartridge. It is imperative that the replacement cartridge be compatible with the filtering requirements for the fuel system. Because for numerous types of qualities, the filter cartridge may dimensionally conform to the base of a given fuel filter assembly, replacement filter cartridges of inferior quality may not comply with the applicable specifications for a given fuel filter assembly and thereby jeopardize the integrity of the fuel filtering system. The replacement with an incompatible filter cartridge can have very serious consequences for the operation of the internal combustion engine and may also be unnecessarily more expensive than the less costly cartridges which are fully suitable. In practice, the owner of the vehicle and/or the maintenance technician servicing the internal combustion engine are frequently totally unaware of replacement filter cartridge specifications and requirements and unknowingly jeopardize the integrity of the filtering system by replacement with a wholly unsuitable cartridge even through the unsuitable cartridge at least cursorily visibly appears to be suitable. There are also, of course, instances where inferior or improper replacement filter cartridges are intentionally installed without the knowledge of the owner or the operator of the vehicle. WO 90/02597 discloses a filter assembly comprising a cartridge received within a bowl which is mounted to a base. A flange projects from the cartridge so that the bowl and cartridge are mountable together to the base. For many applications, it is also desirable that a cartridge be mounted to the base at a specific angular orientation so that warnings, directions and markings affixed to the cartridge may be properly positioned to ensure visibility and maximise the chances of successful information dissemination. In US-A-5 035 797 (U.S. Patent Application No. 480,032 filed on February 14, 1990 and assigned to the assignee of the present invention), a key system for keying a replaceable filter cartridge to the base is disclosed. The filter system is of a type having a base with an inlet and an outlet connection with the engine fuel system and a replaceable filter cartridge mountable to the base. The replaceable cartridge includes a generally cylindrical housing which houses the fuel filter elements. At least one key projects axially from the base. A corresponding slot in the cartridge is dimensioned and located for receiving each corresponding key for locking the cartridge at a fixed angular position of the base. The keys interlock in slots of the cartridge at locations which are closely adjacent to the sealing interface of the cartridge and the sealing lip of the base. A unique matrix of axially projecting keys is formed on each base of a given type, and a unique matrix of slots corresponding to the keys is formed in each cartridge. The key slot matrices are configured so that for a given compatible cartridge and base, the keys are interlockable in the slots to lock the cartridge at a fixed angular position of the base to thereby permit the cartridge to be securely mounted to and sealed to the base. For non-compatible cartridges and bases, the base keys are not mateable and essentially interfere with the mounting and sealing of the non-compatible cartridge so that compatible and non-compatible cartridges may be readily identified. While the key system described in the foregoing patent application represents a significant advancement in assuring suitable fuel filter cartridge replacement, there are replacement cartridge configurations, which are closely similar in appearance to the compatible cartridges and may result in confusion and assembly difficulties. Because the key slots are not readily visible and may be similar in appearance to slots which provide for fuel communication between the cartridge and the base, it is clearly desirable that the cartridge incorporates an additional keying structure which is highly visible to the maintenance technician and may also provide additional coded structural combinations to enhance the integrity and reliability of the key system. According to the invention there is provided a disposable filter cartridge for connecting to a base to form a fuel filter assembly, the filter cartridge having a housing for housing a filter element, the housing defining a generally cylindrical external surface and having a radially extending shoulder and a first end portion defining an axial opening, the filter cartridge having key means for keying with the base, characterised in that said key means is integral with the housing and comprises a plurality of angularly spaced protrusions extending generally radially directly from the surface of the housing so that the spaces between the protrusions terminate inwardly at the cylindrical surface of the housing. The invention extends to a fuel filter assembly comprising a cartridge of the invention and a base for receiving the cartridge of the invention. Briefly stated, the invention in a preferred form is a new and improved key system for assuring compatibility between a replacement filter cartridge and a base for a fuel filter system. The key system may be employed in conjunction with a key system which employs a matrix of axially protruding keys. The keys extending from the base and corresponding complementary slots of the cartridge are dimensioned and positioned for accepting the keys and selectively mounting a suitable cartridge to the base. The filter base preferably is of a type which has an inverted cup-like portion defining a receptacle for receiving the replaceable cartridge. The receptacle is partially defined by axial recesses in the side walls which form tracks. The recesses are defined by equidistantly spaced rails. Several such recesses may be angularly spaced at the receptacle interior. The filter cartridge, which may have a can-like housing comprised of a pair of sections joined along a roll seam, includes a plurality of arcuate protrusions projecting from the cylindrical side surface. The arcuate protrusions are complementary with the spacing of the rails and are angularly positioned so that when the cartridge is connected to the base, the protrusions axially slide along the tracks and are closely received in the corresponding recesses. The projections and the tracks may be dimensioned and positioned to provide a keyed configuration which selectively identifies replacement cartridge compatibility and aids the technician in selecting and installing a suitable replacement cartridge. The protrusions and the corresponding tracks are angularly positioned so as to generally alternate with the key and slot combinations of the base and the cartridge so that essentially a dual key code system is provided. An embodiment of the present invention will now be described by way of example and with reference to the accompanying drawings; wherein Figure 1 is an exploded perspective view of a fuel filter assembly incorporating a key system in accordance with an embodiment of the present invention; Figure 2 is a frontal sectional view, partly broken away, of the assembled fuel filter system of Figure 1; Figure 3 is a top plan view of the cartridge for the fuel filter assembly of Figure 1; Figure 4 is a bottom view of the base for the fuel filter assembly of Figure 1; and Figure 5 is a sectional view, partly broken away and portions removed, of the base of Figure 4 taken along the line 4-4 thereof. With reference to the drawings wherein like numerals represent like parts throughout the several figures, a fuel filter assembly incorporating a key system is generally designated by the numeral 10. Fuel filter assembly 10 comprises a base 12 and a disposable filter cartridge 14 which is secured to the base by means of a retaining ring or collar 16. A dust seal 18 may be interposed between one end of the collar and the base. The filter cartridge 14 houses the filter material which has a defined useful life. The cartridge is periodically replaced with a compatible replacement cartridge. The fuel filter assembly 10 is especially suitable for incorporation into the fuel supply system of an internal combustion engine (not illustrated), such as a diesel engine, to filter particulate material and remove water from the fuel supply to the engine. Although the key system may be employed with a wide variety of fuel filter configurations, the illustrated fuel filter assembly 10 may be similar in form and function to those described in US-A-5 017 285 and US-A-5 035 797, both of which applications are assigned to the assignee of the present invention. The key system of the preferred embodiments is not limited to any specific fuel filter assembly, but is generally applicable to any fuel assembly employing a base which mounts and seals with a replaceable filter cartridge of a generally cylindrical form. The key system of the present invention may be employed either apart from or in conjunction with a key system, such as disclosed in U.S. Patent Application No. 480,032, principal features of which are generally illustrated in the drawings. The illustrated filter assembly is an inverted-type filter assembly wherein the cartridge 14 is suspended generally below the base 12. The cartridge 14 contains a dual stage or other type filtering system which functions to remove particulate matter from the fuel and to separate water from the fuel. The fuel filter assembly 10 may also include a heater unit for heating the fuel during cold conditions to prevent the precipitation of wax crystals from the fuel. The base 12 is preferably a cast member, which includes an integral cast formed mounting bracket 20. The bracket 20 contains one or more slots 22 to facilitate mounting the base to the header or other appropriate structure of an internal combustion engine. The base 12 may further include a coarse filter screen. A head cap 26 is mounted by the base by a threaded ring 27 to secure the screen in position. A sealing ring 28 may also be employed to provide a fluid-tight seal between the cap and the base. The base 12 is an inverted quasi cup-like member which has a central stepped axial bore 32. A conduit or sleeve 34 is received at one end of the upper reduced portion of the base. The lower segment of the stepped bore has an enlarged diameter which receives a second sleeve or conduit 38. The conduits 34 and 38 are disposed in generally concentric relationship and provide for generally axial fluid communication between the cartridge and the base. The base includes a fuel inlet passage 50 and a fuel outlet passage 52. An annular passage 42 which is disposed between the conduits 34 and 38 communicates with the outlet passage. The inlet passage communicates with the passage formed by the conduit 34. A threaded surface 54 at the lower peripheral portion of the base is configured for threaded engagement with the retaining collar 16 for securing the disposable filter cartridge to the base. A lower circumferential lip 56 of the base receives the dust seal 18 which is engaged by the top of the retainer collar 16. An air vent 58 may also be threaded on the side of the base for venting trapped air therein. The lower portion of the base has a generally cylindrical inner surface 60 which defines an upper receiving cavity for an upper portion of the replaceable filter cartridge. A plurality of axially extending keys 70a, 70b, 70c... project from the base at a location which is adjacent the threaded surface 54. The keys preferably have a generally arcuate cross-section and are selectively dimensioned and positioned to provide a unique key matrix for a given filter capacity, filtering quality or filtering parameter as will be detailed below. The disposable filter cartridge 14 comprises a can-like housing formed by a pair of cooperative cup-like sections 80 and 82 which are joined along a circumferential roll seam 84. The larger can section 80 includes an axial opening which receives a drain cock 86. The drain cock 86 is employed for manually draining water from the cartridge. A filter element 90 having a continuous fan-shaped pleated form is housed within the enlarged can section 80. The upper can-like section has a radially outward, compound bend configuration which forms an annular recess. An insert 92 is pressed into the recess and secured in position. The insert defines slots 94a, 94b, 94c... which are complementary with the keys and are dimensioned and positioned for receiving the keys. The reduced can section 82 houses the secondary filter element 96 and has an axial opening which mounts a sealing grommet 98. The sealing grommet diametrally seals the enlarged conduit 38. A medial plate (not illustrated) may also be disposed between the can sections and engage the upper and lower portions of the primary and the secondary filter elements 90 and 96. The medial plate defines an opening which receives and mounts a second sealing grommet (not illustrated). The grommet fluidly seals against the conduit 34. The roll seam 84 preferably forms a retainer shoulder which is engaged by a flange-like rim 17 of the retaining collar for loading the replaceable cartridge to the base. The outer exterior portions of the reduced can section are configured with a matrix of integral, angularly spaced radial protrusions 100a, 100b, 100c..... The protrusions are preferably die-formed and have an outer cylindrical surface portion so as to define an arcuate section transverse to the central axis of the cartridge. The protrusions preferably axially align around the periphery of the cartridge. The radial protrusions preferably angularly alternate with the angular positions of the slots 94a, 94b, 94c.... of the insert 92. The number of protrusions and the arcuate dimensions and the angular positions of the protrusions 100a, 100b, 100c,... are selected to implement a key code to ensure cartridge compatibility with the base. The protrusion matrix illustrated in the drawings merely illustrates one possible configuration which may, for example, correspond to a given filter capacity, dimensional constraint, or filter media or cartridge orientation or various combinations thereof. The base structure which defines the cartridge receiving cavity further includes a plurality of angularly spaced recesses 110a, 110b, 110c..... The recesses have a generally arcuate cross-section and are defined by opposing equidistantly spaced endwalls or rails 112a, 112b, 112c... and 114a, 114b, 114c..... The endwalls and the recesses form tracks which are dimensioned to closely axially receive the protrusions 100a, 100b, 100c.... to angularly key the cartridge to the base. When the cartridge is axially mounted to the base, the protrusions are angularly aligned with the associated tracks and the cartridge is axially pushed onto the base. The recesses or tracks angularly alternate with the axially protruding keys so that a compatible filter cartridge is mountable to the base and mechanically selected in terms of compatibility by proper positioning and alignment of the respective key/slot and/or protrusion/track configurations. The protrusions provide a readily visible key system for the maintenance technician to further facilitate proper selection of the filter cartridge. Various combinations or arrays of corresponding protrusions and tracks may be employed so as to selectively identify compatible and non-compatible filter cartridges for given cartridge filtering capacity, quality and other parameters. The key system embodying a protrusion/track configuration may be employed in conjunction with the key/slot combinations or may be employed apart from the key/slot combinations to provide a key system for defining compatible and non-compatible replacement cartridges. The tracks and protrusions may be uniformly dimensioned or may be non-uniformly dimensioned for a given base/cartridge assembly. The radial depths of the recessed tracks and the corresponding protruding dimensions of the corresponding protrusions may also be varied to provide additional key combinations. For example, as illustrated in Figure 4, depth Db for track 110b is less than depth Dc for track 110c. The radial extent of the corresponding protrusion 100b would be proportionately less than the radial extent of protrusion 100c. Likewise, the axial dimensions or lengths of the tracks and the axial positions of the protrusions may also be varied to provide additional key combinations. For example, as illustrated in Figure 5, the axial length Lt of track 110f is less than the axial length Le of track 110e. The axial positions of the lower terminus of protrusion 110f would be above that of the lower terminus of protrusion 110b. It will be seen therefore that at least in its preferred embodiments the present invention provides a new and improved key system for a fuel filter system; a new and improved replacement cartridge key system wherein the cartridge has a highly visible key structure which corresponds with a given base; and a new and improved fuel filter key system having an efficient construction which provides an effective means for selectively identifying compatible and non-compatible replacement filter cartridges.

Claims: A disposable filter cartridge for connecting to a base (12) to form a fuel filter assembly, the filter cartridge having a housing (80,82) for housing a filter element (90,96), the housing (82) defining a generally cylindrical external surface and having a radially extending shoulder and a first end portion defining an axial opening, the filter cartridge having key means for keying with the base (12), characterised in that said key means is integral with the housing (82) and comprises a plurality of angularly spaced protrusions (100a, 100b, 100c...) extending generally radially directly from the surface of the housing (82) so that the spaces between the protrusions terminate inwardly at the cylindrical surface of the housing. A cartridge as claimed in claim 1, wherein said protrusions (100a,100b,100c...) generally align around the periphery of said housing means (80,82). A cartridge as claimed in claim 1 or 2, wherein said enclosure (82) has a central axis and said protrusions (100a,100b,100c...) have a generally arcuate shaped section portion in a plane orthogonal to said axis. A cartridge as claimed in claim 3, wherein the arcuate dimensions of two of said protrusions (100a, 100b,100c...) are different. A cartridge as claimed in any preceding claim, wherein said protrusions (100a,100b,100c...) are located between said one end and said shoulder means. A cartridge as claimed in any preceding claim, further comprising slot means (92) for defining a plurality of slots (94). A cartridge as claimed in claim 6, wherein said protrusions (100a,100b,100c...) are angularly positioned between said slots (94). A fuel filter assembly comprising a cartridge as claimed in any preceding claim and a base (12) for receiving the cartridge. A fuel filter assembly as claimed in claim 8, wherein the base (12) further comprises a plurality of angularly spaced axial recessed tracks (110a,110b, 110c...) for receiving said protrusions (100a,100b, 100c...). A fuel filter assembly as claimed in claim 9, wherein the base (12) further comprises an inner surface (60) forming a receiving cavity for an upper portion of the disposable filter cartridge and defined by a plurality of angularly spaced axial recessed tracks (110a,110b,110c...) and cylindrical surface sections (70a, 70b,70c...).

Inventors: JANIK LEON P, JANIK, LEON P.
Applicants: STANADYNE AUTOMOTIVE CORP, STANADYNE AUTOMOTIVE CORP.
Application year: 1992
Main classification: B01D35
IPC codes: B01D35, B01D27, F02M37