Abstract:
A fluid filter for the processing of a circulating fluid includes a unitary, molded plastic shell including an annular sidewall defining an open interior space and an annular entrance opening, the sidewall including an exposed edge that is formed with a plurality of recessed slots, a fluid filter cartridge inserted into the interior space of the shell and including a filtering media element and bonded thereto a molded plastic endplate. The endplate includes a plurality of outwardly-extending projections that cooperatively fit into said plurality of recessed slots for fixing the position of the fluid filter cartridge relative to the shell in terms of the axial depth of the cartridge into the shell and for preventing relative rotation or movement between the cartridge and shell.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates in general to a fluid filter incorporating a plastic shell and a replaceable fluid filter cartridge. More specifically, the present invention relates to configuring the shell so that it will only accept, in terms of proper functioning, a cooperatively-configured replaceable fluid filter cartridge.  
         [0002]     One of the emerging technologies in terms of fluid filter construction is the enlargement of the threaded connection interface between the molded plastic shell and the fluid-delivery head, accompanied by the elimination of the typical or traditional nutplate. In one embodiment of this design concept, the shell is molded out of plastic and the outer cylindrical surface of the shell adjacent the open end of the shell is externally threaded. This threaded surface of the shell is used to attach the shell, and in turn the fluid filter assembly, to the head. This style of shell is configured for use with a spin-on style of filtration system as part of a disposable fluid filter assembly.  
         [0003]     Some end users of the type of filtration systems described above enjoy the advantages gained from a replaceable fluid filter cartridge. Therefore, it would be an advance in the state of the art to configure the molded plastic shell, generally as described above, but configured to accept a replaceable fluid filter cartridge. Related to the acceptance of a replaceable cartridge is the inability of the shell to accept a spin-on style of filter as part of a disposable, single-use system. The fluid filter construction disclosed herein is directed to providing this capability by the design of a novel and unobvious fluid filter endplate with cooperative modifications to the upper exposed edge of the shell that defines the open end of the shell.  
       BRIEF SUMMARY OF THE INVENTION  
       [0004]     A fluid filter assembly for the processing of a circulating fluid according to one embodiment of the present invention comprises a shell including a sidewall that defines an interior space and an entrance opening at one end of the shell, the sidewall including an exposed edge adjacent the entrance opening, a fluid filter cartridge installed into the shell resulting from insertion of the fluid filter cartridge into the interior space by way of the entrance opening, the fluid filter cartridge including a filtering media element and an endplate that is attached to one end of the filtering media element, and a structural interface configured for fixing the axial depth of the fluid filter cartridge into the shell, the structural interface including a plurality of first forms configured as part of the exposed upper edge of the shell and a plurality of second forms configured as part of the endplate, the first forms and the second forms being constructed and arranged to cooperatively interfit with each other for fixing the axial depth of the fluid filter cartridge into the shell.  
         [0005]     One object of the present invention is to provide an improved fluid filter assembly.  
         [0006]     Related objects and advantages of the present invention will be apparent from the following description.  
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0007]      FIG. 1  is a front elevational view of a fluid filter assembly according to a typical embodiment of the present invention.  
         [0008]      FIG. 2  is a side elevational view of the  FIG. 1  fluid filter assembly, in full section.  
         [0009]      FIG. 3  is a front elevational view of the  FIG. 1  fluid filter assembly, in full section.  
         [0010]      FIG. 4  is an exploded view of the  FIG. 1  fluid filter assembly.  
         [0011]      FIG. 5  is a front elevational view of a fluid filter cartridge comprising one portion of the  FIG. 1  fluid filter assembly.  
         [0012]      FIG. 6  is a front elevational view of a molded plastic housing comprising a portion of the  FIG. 1  fluid filter assembly.  
         [0013]      FIG. 6A  is a partial, enlarged detail view of one slot style defined by the  FIG. 6  shell.  
         [0014]      FIG. 6B  is a partial, enlarged view of a second slot style also defined by the  FIG. 6  shell.  
         [0015]      FIG. 7  is a side elevational view of the  FIG. 6  shell.  
         [0016]      FIG. 8  is a perspective view of the  FIG. 6  shell.  
         [0017]      FIG. 9  is a top plan view of a molded plastic endplate comprising a portion of the  FIG. 5  fluid filter cartridge.  
         [0018]      FIG. 10  is a front elevational view of the  FIG. 9  endplate.  
         [0019]      FIG. 11  is a perspective view of the  FIG. 9  endplate.  
         [0020]      FIG. 12  is a perspective view of a removal procedure for the  FIG. 5  fluid filter cartridge from the  FIG. 6  housing.  
         [0021]      FIG. 13  is a partial perspective view of the fluid filter assembly showing one flow clearance space for entering fluid.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.  
         [0023]     Referring to  FIGS. 1-5 , there is illustrated a fluid filter assembly  20  that is constructed and arranged for threaded connection to a fluid-delivery mounting head (not illustrated). Fluid filter assembly  20  includes a unitary, molded plastic shell  21  and a cooperating fluid filter cartridge  22 . The fluid filter cartridge  22  (see  FIG. 5 ) includes a generally cylindrical filtering media element or filter media pack  23  and a unitary, molded plastic endplate  24  that is securely attached, such as by adhesive bonding, to the upper end of the filter media pack  23 .  
         [0024]     Referring to  FIGS. 6-8 , the details of plastic shell  21  are illustrated. The generally cylindrical body  27  includes an annular sidewall  28  that defines open end  29 . The plastic shell also includes a closed base  30  that is integral with cylindrical body  27 . While the base  30  is described as “closed”, there are two defined apertures  31  and  32  (see  FIG. 3 ). These two defined apertures provide the capability of water-in-fuel (WIF) sensing ( 31 ) and water drainage ( 32 ) for the fluid filter assembly  20 . The additional socket  35  is for a one-way removal feature. The inner surface  33  of sidewall  28  includes a uniformly spaced-apart series of structural ribs  34 . Ribs  34  are unitarily molded as part of shell  21  and provide structural support and rigidity to the shell as well as a deterrent against the attempted use of any non-standard filter media, such as a spin-on filter style intended for single-use as part of a disposable fluid filter assembly. One feature of note, though not actually illustrated, is the elimination from these inner ribs  34  of any type of rib ledge or shelf that would typically be used to support the filtering element (spin-on, single-use style) as depicted in certain prior constructions. Eliminating any type of rib ledge or shelf and extending ribs  34  axially provides the mentioned structural support to shell  21  and eliminates any support structure that might otherwise control the axial depth of an installed fluid filter cartridge. This structural design change to the shell  21  in turn requires some utilization of the open end  29  in order to control the insertion depth of any fluid filter or filter media pack into the shell  21 .  
         [0025]     The outer surface  37  of sidewall  28  adjacent upper edge  38  of open end  29  is constructed and arranged with a series of molded threads  39  that are used to securely attach fluid filter assembly  20  to the fluid-routing head (not illustrated). Further, the sidewall  28 , in cooperation with the closed base  30 , defines a generally cylindrical interior space for shell  21  that is constructed and arranged to receive the fluid filter cartridge  22 . Upper edge  38  that helps to define open end  29  is considered to be an exposed or free edge and open end  29  constitutes the entrance opening of the shell, noting that the opposite end of the shell includes closed base  30 . As noted, the fluid filter cartridge  22  is installed into the shell by inserting the fluid filter cartridge into the interior space by way of this entrance opening.  
         [0026]     Shell  21  represents the type of molded plastic shell that is used without a “nutplate” as that component term would be understood to mean as part of conventional fluid filter terminology. The enlarged series of outer threads  39 , in terms of the outside diameter size of shell  21 , requires a unique or special head design so as to change from the head structure that would be used for head connection to a nutplate. Shell  21  is constructed and arranged so as to reject or prevent the insertion of a spin-on style of fluid filter. In terms of generally accepted terminology, the understanding of a spin-on, single-use filter is that the overall fluid filter assembly would be considered as disposable after a single use cycle. Structurally, the wall thickness can be somewhat less for a single use filter assembly as compared to the desire for a slightly thicker wall when the shell is designed for multiple uses., i.e., reuse with replaceable fluid filter cartridges, as presented for the disclosed invention. If the same basic shell shape is going to be used for both types of fluid filter assemblies, disposable as well as multiple use, various design changes will be made.  
         [0027]     Reference to the same basic shell shape means that the exterior size and shape are generally the same whether the intended end use is as part of a spin-on, disposable fluid filter assembly or as part of a fluid filter assembly that includes a replaceable filter cartridge. There are though differences between these two styles of filter assemblies in terms of the final shell configurations. While the overall basic shell shape may begin somewhat the same for these two styles of fluid filter assemblies, the inner core for the interior molding of the shell is sized and shaped differently depending on the particular fluid filter assembly style that will utilize the particular shell.  
         [0028]     As for some of the shell design differences, the spin-on, disposable style does not require any notches or slots, as shown in  FIGS. 6, 6A  and  6 B, while the replaceable, cartridge style requires these notches. For the spin-on, disposable style, radial ledges are used as part of the structural ribs on the interior of the shell to position the fluid filter element and to set its axial height down into the interior of the shell. The replaceable cartridge style does not use any radial ledges since its axial depth and positioning are controlled by the endplate configuration and its interfit into the spaced series of six notches or slots  42  and  43 . When the rib ledges are molded as a part of the unitary plastic shell, the interior space of the shell is described as having an interior abutment ledge. This is the surface that supports or otherwise positions the lower portion of the installed fluid filter element to maintain the proper axial depth of that element into the shell. When the inwardly extending radial rib ledges are not molded as part of the shell interior, then the shell interior space is described herein as being “open”.  
         [0029]     If a spin-on, disposable style of fluid filter assembly is selected, the core diameter for the shell molding process is increased in size, resulting in a thinner wall as compared to the increased wall thickness desired for the replaceable, fluid filter cartridge style. This difference in wall thickness assumes that the overall outer size and shape of the shell is basically the same for both of these fluid filter assembly styles. It is simply a reality that when the fluid filter assembly is designed as a single-use, disposable assembly, the shell wall thickness does not have to be as great as when the shell is used and re-used multiple times. Varying the shell wall thickness is achieved by varying the inserted core diameter during the molding process. Since these fabrication differences between the two styles of shells can be integrated into the same production line, there are some resulting efficiencies. While these efficiencies are important and while the ability to use the same basic style of shell is important, the present invention focuses more on the replaceable, fluid filter cartridge design and the manner in which the cartridge and shell cooperate with one another, as disclosed herein.  
         [0030]     The use of a fluid filter assembly that is configured for use with a replaceable cartridge style filtering element provides various features that some end users prefer and see as advantages as compared to a disposable, single-use fluid filter assembly. For example, when the shell is reused, there is less associated scrap and there is reduced service interval cost. The use of a replaceable fluid filter cartridge permits the easy change (replacement) of the fluid filter cartridge by simply pulling out the used fluid filter cartridge and inserting a new fluid filter cartridge into the interior space of the shell.  
         [0031]     In order for shell  21  to be configured for use with a replaceable cartridge style of fluid filter element, according to what is disclosed herein, the upper exposed edge  38  is configured with a series of six (6) recessed notches or slots (see  FIGS. 6, 6A  and  6 B). In the preferred embodiment that is illustrated, there are two slots  42  that are constructed and arranged with a first shape and four slots  43  that are constructed and arranged with a second shape that is slightly different from the first shape. In one arrangement of the disclosed fluid filter assembly, these six slots  42  and  43  are equally spaced around upper edge  38 . For this one arrangement of six (6) slots, the replaceable fluid filter cartridge  22  can be installed in any one of six orientations in terms of its rotation relative to the shell, as will be described herein as part of the description of the fluid filter cartridge  22  and endplate  24 . In a second arrangement, the spacing between the series of six (6) slots  42  and  43  is not equal, but random or varied, such that there is only a single orientation for the fluid filter cartridge to insert. into the shell  21 . Going to a varied spacing for the six slots requires a corresponding varied spacing for the projections  46  of the endplate  24 , as described herein. Since the random spacing between slots  42  and  43  may not be a high priority with a majority of end users, the focus of the present disclosure is on equal spacing where the notch or slot centerlines are sixty degrees apart and the replaceable, fluid filter cartridge  22  is able to be installed in the shell in any one of six positions.  
         [0032]     Referring to  FIGS. 9-11 , the details of plastic endplate  24  are illustrated. The filtering media pack  23  is a generally cylindrical, pleated, filtering media structure or element and the plastic endplate  24  is adhesively bonded to the upper exposed end of the filter media pack  23  in order to create fluid filter cartridge  22 . Endplate  24  is a unitary, molded plastic component that includes an open cylindrical sleeve  44  for receipt by the head for routing of the exiting fluid after it passes through the filtering media pack  23 . An annular face seal (sealing) gasket  45  is positioned around sleeve  44  (see FIGS.  2  and  3 ) for a liquid-tight sealed interface between the endplate  24  and the head. As the shell threads onto the head, the gasket  45  engages a surface of the head causing gasket compression with continued threaded engagement.  
         [0033]     Seating of the fluid filter cartridge  22  into shell  21  is achieved by the use of slots  42  and  43  and cooperating outwardly-extending radial projections  46 . There are six projections  46  that are constructed and arranged to match the spacing of the slots  42  and  43 . Each projection  46  has an L-shaped form with an upper, outwardly extending section  46   a , an axially depending section  46   b , and a lower, outwardly extending radial lip  46   c . While there are two styles of slots  42  and  43  as described and as will be explained in greater detail, all six projections  46  are constructed and arranged with the same size and shape. Each projection  46  includes concave side surfaces  46   d  and  46   e  (see  FIG. 9 ), creating the appearance of an outwardly tapering shape for each projection  46 . Radial lip  46   c  is constructed and arranged with a generally horizontal, substantially flat lower surface  46   f.    
         [0034]     As is illustrated and as would be understood from the foregoing descriptions, upper edge  38  of sidewall  28  defines open end  29 . The inside diameter surface of upper edge  38  (or sidewall  28  at its upper end) coincides with the outside diameter of the open area of the generally circular open end  29 . In order to guarantee that the fluid filter cartridge  22  uses upper edge  38  for the positioning of cartridge  22  within shell  21 , the outside diameter dimension of the endplate  24 , as measured over or across the outer tips of the projections  46 , exceeds the outside diameter of the open area of open end  29 . It is also noted that the outside diameter across the outer tips of projections  46  does not extend beyond the outside diameter of shell  21 , at least not to any noticeable degree or extent that would potentially interfere with the threaded connection of the shell  21  to the head.  
         [0035]     In terms of the number of slots and the number of projections, it will be noted that the proper assembly of the fluid filter cartridge  22  into shell  21  requires a receiving slot, either  42  or  43 , for each projection  46 . If there are any slots in upper edge  38  that do not receive a projection  46 , then there is a gap left at that location on edge  38 . If there is an “extra projection  46  that does not have a corresponding receiving slot, properly sized and positioned, it will cause interference with the upper edge  38  of shell  21  at the time of attempted installation of the cartridge  22  into the shell  21 . This interference of a projection  46  resting on top of edge  38  prevents proper seating of the fluid filter assembly against the head. The assembly and proper seating of fluid filter cartridge  22  into shell  21  is illustrated in  FIGS. 2 and 3 . This proper seating positions each projection  46  down into a corresponding one of the receiving slots  42 ,  43 . The two slots  42  are constructed and arranged for a secure capture of the inserted projection  46  by an interference fit. The other four slots  43  are each constructed and arranged for a close clearance receiving fit of their corresponding projection  46 . These other four slots  43  provide support for the fluid filter cartridge  22 . All six slots  42 ,  43  cooperate with their receiving projections  46  in order to set the desired insertion depth of the fluid filter cartridge  22  into shell  21 . The interfit between the projections  46  and slots  42 ,  43  also prevents any rotation of the fluid filter cartridge  22  relative to shell  21 , once the fluid filter cartridge is properly installed. It will also be noted from the various figures that each projection  46 , specifically the radial lip  46   c , is recessed below the upper surface of exposed upper edge  38 . The number of slots  42  and the complementing number of slots  43  can be varied from 6-0 to 0-6 and all combinations between these extremes. If added security is desired in terms of physically capturing one or more of the projections  46 , then the side walls of the receiving slot can be shaped with detent ribs or bumps for a snap fit.  
         [0036]     Slot  42  is illustrated in greater detail in  FIG. 6A  and slot  43  is illustrated in greater detail in  FIG. 6B . The broken line outline in each of these two drawing figures represents the shape and proper positions of section  46   c  of the received projection  46 . The construction and arrangement of each slot  42  creates a sufficiently tight interference fit with the received projection  46  to anchor and hold the fluid filter cartridge  22  into shell  21 . As illustrated, a small clearance space  49  is defined beneath section  46   c  and is located between lower surface  50  of slot  42  and the flat lower surface  46   f  of the corresponding projection  46 . The clearance space  49  is used to receive the flat tip of hand tool, such as a screwdriver, in order to be able to pry up on the corresponding projection  46  that is received within slot  42  in order to pop the projection free of its interference fit (see  FIG. 12 ). As noted, it is not possible to install the fluid filter cartridge  22  unless the correct shell  21  has been selected.  
         [0037]     Due to the outwardly extending design of projections  46  in a radially outward direction from the outer circular edge  51  of endplate  24 , flow clearance spaces  52  are defined between each pair of adjacent projections  46 . See  FIG. 13  for one example of a defined flow clearance space  52 . These clearance spaces provide the necessary flow channels into shell  21  for the fluid to be filtered by the filtering media element. The outline of each clearance space  42  is defined by the inner surface of upper edge  38 , the outer circular edge  51 , and the adjacent pair of projections  46 . These six clearance spaces  52  provide a flow path for the fluid to be filtered that arrives by way of the head and flows onto the endplate outside of the return flow sleeve  44 . This allows faster and smoother routing of the fluid flow in view of the number and size of the flow openings (i.e., clearance spaces  52 ) and enables more efficient fluid filtration and processing. As the fluid to be filtered flows across the exposed surface of the endplate, it reaches the flow clearance spaces  52  and flows through these spaces to the annular clearance space defined by and between the inside surface  33  of the sidewall  28  and the outer cylindrical surface (pleated) of the filter media pack  23 .  
         [0038]     The style of fluid filter cartridge  20  described herein includes a couple of additional benefits to the end user in terms of performance, simplicity, and cost. The cartridge endplate  24  and cooperating shell  21  eliminate the possibility that an incorrect or improper fluid filter cartridge will be installed. Any cartridge without the proper number, style, and spacing of endplate projections  46  will not fit “properly” into the shell  21 . The elimination of the rib ledge structures from the axially extending ribs  34  means that there is nothing to support the non-approved fluid filter cartridge when inserted into the shell and there is nothing to set or control the desired depth for the cartridge except for the upper edge  38  of sidewall  28  of shell  21 . If the upper edge is attempted to be used in some manner to control the depth of the cartridge, it means that the edge cannot fit flush against or within the head. This also prevents proper compression of the gasket or seal and will result in leakage. The only option for a proper assembly and proper fit to the head is to utilize slots  42  and  43  with the designed number of cooperating projections as part of the endplate. However, that cooperating structure would mean an endplate conforming to the configuration of endplate  24  and thus the only fluid filter cartridge fully compatible with shell  21  is to use one that is designed to cooperate with slots  42  and  43 . The retention capability afforded by the interference fit and insertion of projections  46  into slots  42  and  43  means that there will be an important retention feature during the assembly process.  
         [0039]     Another benefit derived from the cartridge  22  and shell  21  combination is the option for an increased media area. By using the endplate  24  and the upper edge  38  to set the axial depth of cartridge  22 , the media portion of the cartridge can be longer. As compared to other designs using the rib ledges for cartridge positioning, the longer media portion means more media and an increased media area. The present invention raises the upper edge of the cartridge closer to edge  38  and the opposite end can be extended deeper into the shell.  
         [0040]     While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.