Abstract:
An oil-conditioning filter, for use with an internal combustion engine, includes a mechanical filter element and a central additive cartridge, for gradually dispensing an oil additive over time. The additive cartridge has a beneficial oil-conditioning agent contained therein. The additive may be provided as a solid block within a storage chamber of the cartridge, or may be a plurality of pellets. Central placement of the cartridge allows for fluid filtration through the mechanical filter element before the additive is added thereto, reducing the likelihood that the additive will be filtered out prematurely upon its initial release. An additive cartridge for installation in an oil filter is also described, including a baffle portion and a storage chamber. Alternative exemplary embodiments of the additive cartridge may include a cylindrical shell, a basket which is operatively attached to an oil filter center tube, or a porous center tube.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    The present application is a continuation-in-part of application Ser. No. 09/867,973, filed May 30, 2001, and published as US 2002/0014447, the disclosure of which is incorporated by reference herein. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to an additive dispensing cartridge for an oil filter assembly, and to an oil filter incorporating the cartridge. More particularly, the present invention relates to an additive dispensing cartridge containing a beneficial additive composition, and to an oil filter having a centrally located additive dispenser incorporated therein. Even more particularly, the present invention relates to an oil filter in which a centrally located additive dispenser, containing one or more oil-conditioning compounds therein, is operable to slowly release the oil conditioning compounds, over time, into filtered engine oil on the downstream, or ‘clean’ side of the mechanical filter element.  
           [0004]    2. Description of the Background Art  
           [0005]    Many different types of fluid filters are known. Most such filters use a mechanical or ‘screening’ type of filtration, with a replaceable cartridge having a porous filter element therein, through which the oil is repeatedly cycled to remove impurities.  
           [0006]    In the oil filtration art, it is well known that normal operation of an internal combustion engine, particularly a diesel engine, results in the formation of contaminants. These contaminants include, among others, soot, which is formed from incomplete combustion of the fossil fuel, and acids that result from combustion. These contaminants are typically introduced into the lubricating oil during engine operation, and tend to increase oil viscosity and generate unwanted engine deposits, leading to increased engine wear.  
           [0007]    The conventional solution to these problems has been to place various additives into lubricating oils, during their initial formulation. In order to combat soot-related problems, many conventional lubricating oils include dispersants that resist agglomeration of soot therein. These work well for a short period, but may become depleted. Additionally, due to the solubility and chemical stability limits of these dispersants in the oil, the service lives of the lubricating oil and the oil filter are less than optimal.  
           [0008]    In order to counteract the effects of acidic combustion products, many conventional motor oils include neutralizing additives known as over-based detergents. These are a source of TBN (total base number), which is a measure of the quantity of the over-based detergent in the oil. The depletion of the TBN is an important limiting factor for many internal combustion engines, and in particular for heavy-duty applications with diesel engines.  
           [0009]    In order to improve engine protection and to combat other problems, conventional lubricating oils often include one or more further additives, which may be corrosion inhibitors, antioxidants, friction modifiers, pour point depressants, detergents, viscosity index improvers, anti-wear agents, and/or extreme pressure additives. The inclusion of these further additives may be beneficial; however, with conventional methods, the amount and concentration of these additives are limited by the ability of lubricating oils to suspend these additives, as well as by the chemical stability of these additives in the oil. Examples of oil filters which include extra additives for the oil include U.S. Pat. Nos. 4,075,097, 4,144,169, 5,591,330, 5,725,031, and 6,045,692.  
           [0010]    An oil filter including a central receptacle for holding and dispensing a solid lubricant in powdered form is disclosed in U.S. Pat. No. 5,032,259 to He et al.  
           [0011]    Other solutions have been proposed in addition to the conventional method of mixing additives with lubricating oil. For example, in order to combat the buildup of sludge in oil, U.S. Pat. No. 5,042,617, issued in 1991 to Brownawell, and entitled Method of Reducing the Presence of Sludge in Lubricating Oils; and U.S. Pat. No. 5,478,463, issued in 1995 to Brownawell et al, and entitled Method of Reducing Sludge and Varnish Precursors in Lubricating Oil, each disclose an oil filter and method for reducing the amount of sludge in lubricating oil as it circulates through an engine. These Brownawell patents provide for the inclusion of particles in an oil filter that are oil insoluble and oil wettable, and which complex with sludge, such that at least some of the sludge that these particles come into contact with is immobilized on the particles. The Brownawell &#39;617 patent discloses the inclusion of oil insoluble and oil wettable particles in an oil filter that are retained on a divided substrate, whereas the Brownawell &#39;463 patent discloses the inclusion of such particles that are not retained on a substrate, but are nonetheless retained in the oil filter.  
           [0012]    Another Brownawell patent, which relates to the reduction of combustion acids in lubricating oil, is U.S. Pat. No. 5,069,799 issued in 1991 and entitled Method For Rejuvenating Lubricating Oils. This patent discloses an oil filter and method for reducing the amount of combustion acids in lubricating oil. In particular, it discloses a method of rejuvenating lubricating oil, which includes reduction of combustion acids, by serially passing the oil through first a chemically active filter media, then a physically active filter media, and finally an inactive filter media. In this &#39;799 patent, the chemically active filter media includes a strong base, to displace weak bases that have combined with combustion acids. The combustion acid and the strong base then combine to form a salt, which is then physically trapped by subsequent mechanical filter media.  
           [0013]    U.S. Pat. No. 5,225,081 to Brownawell discloses method of removing polynuclear aromatics from used lubricating oil. The method of the Brownawell &#39;081 reference involves passing oil through a staged oil filter system, which may include a chemically active filter media. The chemically active filter media is made of a composite material including particles of an active component and a thermoplastic binder, which are a product of a heated extrusion process. Basic conditioners are given as one example of materials suitable for use as chemically active filter media. Activated carbon is also emphasized as a preferred component of the filter media in this reference.  
           [0014]    Some designs for multiple stage oil filters are known, such as those disclosed in U.S. Pat. Nos. 4,557,829 and 4,886,599. U.S. Pat. No. 4,886,599 to Bachmann et al. discloses a filter cartridge with sequential concentric cylindrical filter elements, for both chemical and mechanical filtration of oil contained in an oil-sealed vacuum pump.  
           [0015]    Other designs for oil filters that contain extra additives and dispense those additives into oil, over time, are disclosed in U.S. Pat. Nos. 5,552,040, and 5,591,330. Some designs are also known for heavy duty coolant filters which release additives over time, such as those disclosed in U.S. Pat. Nos. RE 37,369, 5,741,433, and 5,948,248.  
           [0016]    U.S. Pat. No. 6,238,554 to Martin, Jr. et al discloses a fuel filter including an inner housing assembly containing a soluble fuel additive composition.  
           [0017]    While the known filters are usable for their intended purposes, the release of supplemental additives from the known filters often takes place either immediately after installation or more rapidly than is needed for protecting the oil. Subsequently, after some time has elapsed, there may be little or no additive left in the filter.  
           [0018]    Another problem with many of the known filter designs is that beneficial additives are added to the oil before the oil is mechanically filtered through a filter element. As a result, when the oil is mechanically filtered, some of the beneficial additives that have just been added may be immediately filtered out.  
           [0019]    A need still exists in the art for an improved oil filter having a beneficial oil additive incorporated therein, which additive is slowly released over the useful life of the filter. A need also exists for an improved oil filter which could extend the useful life of engine oil, so as to allow a user to extend the time interval between oil changes in a vehicle, particularly a vehicle having a diesel engine.  
         SUMMARY OF THE INVENTION  
         [0020]    The present invention provides an improved oil filter, having a basic conditioner and/or another beneficial additive incorporated therein. In the practice of the present invention, the beneficial additive is housed within a centrally located additive dispenser cartridge, which is operable to dispense an additive composition into relatively clean filtered oil that has already passed through a mechanical filter element.  
           [0021]    In a particular embodiment of the invention, the additive chamber includes an additive cartridge which is a hollow shell, and a beneficial additive contained within the housing. The additive chamber is located inside of the mechanical filter element at a central part of the filter, so that the oil has already been mechanically filtered when additive is added thereto.  
           [0022]    The apparatus according to the invention may also include a baffle for directing oil flow, and the additive cartridge may be attached to the baffle. Where the baffle is used, a dividing wall may be provided between the baffle and the additive chamber.  
           [0023]    The additive cartridge has at least one opening, and may have a limited number of openings therein to control the rate of diffusion therefrom.  
           [0024]    Accordingly, it is an object of the present invention to provide an improved oil filter including one or more beneficial oil additives that are released slowly over the life of the filter.  
           [0025]    For a more complete understanding of the present invention, the reader is referred to the following detailed description section, which should be read in conjunction with the accompanying drawings. Throughout the following detailed description and in the drawings, like numbers refer to like parts. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]    [0026]FIG. 1 is a perspective view of an oil filter in accordance with a first embodiment of the present invention;  
         [0027]    [0027]FIG. 2A is a side plan view of a first variation of the oil filter of FIG. 1, partially cut away and partially shown in cross-section, wherein a hollow additive cartridge contains a solid block of an additive composition;  
         [0028]    [0028]FIG. 2B is a side plan view a second variation of the oil filter of FIG. 1, partially cut away and partially shown in cross-section, wherein a hollow additive cartridge contains a plurality of pellets formed of an additive composition;  
         [0029]    [0029]FIG. 3 is a perspective view of an additive cartridge, which is a component of the oil filters of FIGS. 1, 2A and  2 B;  
         [0030]    [0030]FIG. 4 is a side plan view of the additive cartridge of FIG. 3; and  
         [0031]    [0031]FIG. 5 is a cross-sectional view of the additive cartridge of FIGS. 3 and 4, taken along the line  5 - 5  in FIG. 3;  
         [0032]    [0032]FIG. 6 is a side plan view, partially in cross section, of an alternative additive cartridge in accordance with a second embodiment of the invention, wherein the cartridge takes the general form of a basket;  
         [0033]    [0033]FIG. 7 is a cross-sectional view of the cartridge of FIG. 6, showing a solid additive concentrate therein; and  
         [0034]    [0034]FIG. 8 is a side plan view of another alternative additive cartridge in accordance with a third embodiment of the invention, wherein the cartridge takes the general form of a hollow center tube with an additive composition contained therein. 
     
    
     DETAILED DESCRIPTION  
       [0035]    Throughout the present specification, relative positional terms like ‘upper’, ‘lower’, ‘top’, ‘bottom’, ‘horizontal’, ‘vertical’, and the like are used to refer to the filter and components in the orientation thereof shown in the drawings. These terms are used in an illustrative sense to describe the depicted embodiments, and are not meant to be limitative. It will be understood that in a specific application thereof, a filter may be installed on an engine in an orientation different from that shown in the drawings, such as inverted 180 degrees or transverse to that shown, and in such a case, the above-identified relative positional terms will no longer be accurate.  
         [0036]    Referring to FIGS. 1 and 2A, there is shown an oil filter  20  according to a first preferred embodiment of this invention. The direction of oil flow, through the filter  20 , is shown by the arrows in FIG. 2A, which illustrate a flow path through the filter.  
         [0037]    The oil filter  20  generally includes a hollow cylindrical housing  22  which defines a hollow chamber  14  therein, a porous, mechanical filter element  15  within that chamber, and a centrally located additive cartridge  18 , also retained inside the housing chamber  14 .  
         [0038]    The housing  22  includes a hollow, generally cylindrical case  21 , and a base plate  24  sealingly attached to the case.  
         [0039]    A foraminous center tube  17  may, optionally, be provided within the filter housing  22  to supportively reinforce the mechanical filter element  15  thereon.  
         [0040]    An anti-drainback valve  19  is provided inside the filter housing  22 , at the base of the center tube  17 , to keep oil in the filter  20  during engine shutoff, when the filter is mounted in the orientation shown in FIG. 2. The oil filter  20  may incorporate a spring-loaded pressure relief valve of a type known to those in the art. A retainer  45  may be provided above the center tube  17 , to exert a downward pressure thereon.  
         [0041]    The housing base plate  24  includes a plurality of inlet ports  28  formed therethrough and arranged in a circular pattern. The base plate  24  also includes a central outlet port  26 . The outlet port  26  has a plurality of female threads formed therein, to allow rotatable mounting of the filter  20  on an externally threaded hollow tubular fitting on an engine block (not shown). An annular external seal or gasket  33  (FIG. 1) fits engagingly into a groove  30  formed at the bottom surface of the base plate, to resist oil leakage outwardly from the base of the filter.  
         [0042]    In the depicted embodiment of FIGS.  1 - 2 , the mechanical filter element  15  includes a conventional cylindrical member made of accordion-pleated filter paper.  
         [0043]    The Additive Cartridge—First Embodiment  
         [0044]    Further in the embodiment of FIGS.  1 - 2 A and  3 - 5 , the filter  20  contains an additive cartridge  18  disposed centrally and coaxially inside of the center tube  17 , in the middle of the mechanical filter element  15 . The additive cartridge  18  includes a hollow cartridge shell  35 , provided in a generally cylindrical shape, closed at the top and open at the bottom thereof in the orientation shown. The additive cartridge  18  also includes a solid additive composition  16  inside of the cartridge shell  35 .  
         [0045]    The hollow cartridge shell  35  has a cylindrical side wall  36  with a plurality of apertures  37  formed in a lower portion thereof. The cartridge shell  35  also includes a cap  38 , which covers the top of the side wall  36  and is integrally formed therewith.  
         [0046]    As seen in the cross-sectional view of FIG. 5, the cartridge shell  35  also includes a horizontal dividing wall  39  extending across a part of the side wall  36  above the apertures  37 . The dividing wall  39  subdivides the shell  35  into two sections, a lower baffle portion  40  and an upper dispenser housing  41  containing a hollow storage chamber  42  therein.  
         [0047]    The cartridge shell  35  has at least one opening  25  formed therethrough to allow fluid communication between the storage chamber  42  and the exterior of the cartridge. The opening(s) may be formed in the side wall  36 , the cap  38 , and/or the dividing wall  39 . The number and size of the opening(s)  25  may be selected to control the rate of dissolution of the additive material  16  from the dispenser housing  41  for a particular application.  
         [0048]    In the embodiment of FIGS.  2 - 5 , the additive cartridge  35  also has a horizontal flange  44  extending transversely outwardly from the side wall  36  at the base of the baffle  40 . The flange  44  may be included to cooperate with the anti-drainback valve  19 , to help seal against fluid bypassing the mechanical filter  15  under normal operation conditions.  
         [0049]    In the practice of the present invention, the additive cartridge  18  is preferred to be located in the flow path downstream of the mechanical filter element  15 , in order to allow the beneficial additive composition thereof to be released into the oil on the clean side of the filter element, after mechanical filtration has been achieved.  
         [0050]    The Additive Composition  
         [0051]    The additive cartridge  18  contains a beneficial additive composition therein, which may be a solid block  16 , as shown in FIG. 2A. In other words, the additive composition  16  may be solid at standard temperature and pressure, defined as 25 degrees C. and one atmosphere pressure.  
         [0052]    The additive composition  16  may be injected into the cartridge shell  35  in a hot liquid state, and allowed to solidify as it cools. Alternatively, the additive composition  16  may be added in powdered form, or may be dispersed in a grease or wax. The additive composition  16  is preferred to be at least partially soluble in hot engine oil.  
         [0053]    The additive composition  16  includes one or more additives which may be selected from the group including basic conditioners, corrosion inhibitors, metal deactivators, antioxidants, dispersants, friction modifiers, oil stabilizers, pour point depressants, detergents, viscosity index improvers, anti-wear agents, extreme pressure additives, mixtures of the above additives, and/or other known beneficial additives.  
         [0054]    The basic conditioner of the additive cartridge, where used, is preferably a basic salt selected from the group consisting of calcium carbonate, potassium carbonate, potassium bicarbonate, aluminum dihydroxy sodium carbonate, magnesium oxide, magnesium carbonate, zinc oxide, sodium bicarbonate, sodium hydroxide, calcium hydroxide, potassium hydroxide, and mixtures thereof.  
         [0055]    The material selected for the cartridge shell  35  is preferred to be a material which remains stable in a hot oil environment. Preferred materials are metals such as steel and oil-tolerant plastics such as, e.g., polyacetals. The cartridge  18  allows the beneficial additive composition  16  to be slowly released into the oil, thereby conditioning the oil in a metered manner over time.  
         [0056]    Alternatively, as shown in FIG. 2B, the concentrated additive composition in the cartridge  18  may be provided as a plurality of separate individual pellets  48 , in order to provide greater surface area than is afforded with the solid additive block  16  of FIG. 2A.  
         [0057]    Where pellets  48  are used, they may be disassociated and separate from one another.  
         [0058]    Alternatively, the individual additive-dispensing pellets  48  housed within the cartridge shell  35  may be bonded together or otherwise cohesively associated with one another to form a substantially integral, yet highly porous structure capable of independent self-support. Where the pellets  48  are joined together in this way, the cartridge shell  35  is not required, and may be omitted if desired.  
         [0059]    During use, as hot oil slowly flows past and around the cartridge  18 , some of the oil enters the dispenser housing  41  via the opening  25 , causing a small amount of the beneficial additive  16  to pass outwardly from the dispenser housing, and to mix with the oil. Where used, the basic salt component of the additive  16  acts to counteract and neutralize acidic combustion products. This neutralization of acidic combustion products allows for a much longer useful life of some other oil additives such as, for example, dispersants and zinc dialkyldithiophosphate (ZDP), which are provided in the oil by the manufacturer thereof. This, in turn, allows for greater intervals between oil changes than is possible without the chemically active filter element.  
         [0060]    The Additive Cartridge—Second Embodiment  
         [0061]    Referring now to FIG. 6, an additive cartridge  218  in accordance with a second embodiment of the invention is shown. Unless specified or depicted as being different herein, the additive cartridge  218  is substantially similar to the additive cartridge  18  as previously described. Those in the art will understand that the additive cartridge  218  of FIG. 6 may be substituted into the oil filter  20  of FIG. 2A instead of the additive cartridge  18  thereof, located above the center tube as indicated by FIG. 6.  
         [0062]    The cartridge  218  in this embodiment includes a hollow cartridge shell  235  in the form of a basket. The shell  235  is either supported by or otherwise attached to the center tube  217 . While the center tube  217  is shown in simplified form in the drawings, it will be understood that it is a porous member. The shell  235  may include a top flange  219  for connecting to the center tube. The shell  235  has a recessed space formed in the top thereof for supportively receiving a retainer spring  245 . The shell  235  also has one or more openings  225  formed therein to allow fluid communication with between the interior thereof and the space surrounding the shell. A solid additive concentrate  216  is provided inside of the shell  235 , in a manner similar to that described above for the first embodiment. The additive may be in one piece or may be pelletized.  
         [0063]    The Additive Cartridge—Third Embodiment  
         [0064]    Referring now to FIG. 8, an additive cartridge  318  in accordance with a third embodiment of the invention is shown. Unless specified or depicted as being different herein, the additive cartridge  318  is substantially similar to the additive cartridge  18  as previously described. Those in the art will understand that the additive cartridge  318  of FIG. 8 may be substituted into the oil filter  20  of FIG. 2A instead of the additive cartridge  18  and center tube  17  thereof.  
         [0065]    The cartridge  318  in this embodiment is a modified center tube. In the embodiment of FIGS.  6 - 7 , the cartridge  318  includes a hollow cylindrical shell  335  with a solid additive  316  contained therein. The shell  235  also has one or more openings  325  formed therein to allow fluid communication with between the interior thereof and the space surrounding the shell. A solid additive concentrate  316  is provided inside of the shell  235 , in a manner similar to that described above for the first embodiment. The additive may be in one piece or may be pelletized.  
         [0066]    Although the present invention has been described herein with respect to a number of preferred embodiments thereof, the foregoing description is intended to be illustrative, and not restrictive. Those skilled in the art will realize that many modifications of the preferred embodiments could be made which would be operable. All such modifications, which are within the scope of the claims, are intended to be within the scope and spirit of the present invention.