Abstract:
A spin-on oil filter can be mounted in an easily accessible position on an engine by means of an oil filter housing comprising a lower housing unit, which comprises an open-topped chamber, and an upper housing unit. A male threaded portion, adapted to mount a spin-on oil filter, extends up from the bottom surface of the lower housing unit. A flat gasket sealing surface is located on the bottom surface, wherein the gasket surface is perpendicular with the male threaded portion. The housing comprises three passages: (i) a first passage adapted to permit flow of dirty oil to an oil filter mounted on the male threaded portion; (ii) a second passage adapted to permit flow of filtered oil away from an oil filter mounted on the male threaded portion; and, (iii) a third passage adapted to permit drainage of oil from the open-topped chamber. The upper housing unit is removably attached to the lower housing unit, and is adapted to cover the open-topped chamber. Methods of maintaining the filter and of adding refill oil are facilitated by this housing.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates generally to oil filters for internal combustion engines, and more specifically to providing easier access to the oil filter.  
       BACKGROUND OF THE INVENTION  
       [0002]     Many small utility engines are provided with an oil filter to remove harmful contaminants from the engine lubricating oil, thereby extending the life of the engine. The most common type of filter used is an automotive style spin-on filter. This type of filter is low in cost and has many of the features generally required of an oil filter built into the disposable assembly (such as a housing capable of withstanding the system operating pressure and a pressure relief valve to prevent oil starvation should the filter element become plugged).  
         [0003]     One main problem encountered with using this type of filter is mounting it to the engine crankcase where it will be readily accessible for service. Another problem associated with this filter is collecting spilled oil when removing the old oil filter. In many typical placements of a spin-on type of oil filter, what appears to be an accessible location on a bare engine becomes difficult to access and service when the engine is installed in an application.  
         [0004]     Many small utility engine designs have filters that are mounted low on the engine, near the mounting base where the engine is fastened to the application it is powering. In many applications for small utility engines, the engine mounting base is found low in the unit and surrounded by components that can make access to the oil filter very difficult. A review of small utility engine applications will show the top-side of the engine is generally accessible in many applications. Using conventional methods of attaching a spin-on oil filter to the engine crankcase, locating the filter on the top-side of the engine would result in the filter oriented upside down. During removal for servicing, much of the oil contained within the filter would spill over the top of the engine.  
         [0005]     Another option commonly used to improve access to oil filters when the installation leaves little room for servicing, is to remote-mount the filter, using hoses or other external conduits to carry the oil to the remotely mounted filter. This is an expensive option, adding a pair of expensive hose assemblies and a remote-mounting bracket, but is preferable to an application with an inaccessible oil filter.  
         [0006]     There are existing oil filter housing designs that can overcome the problems listed with the above designs (access to filter, spillage during servicing, and use as an oil fill), but these designs do not use spin-on oil filters. These known variations use cartridge type oil filters. Examples of this type of filter design include the following U.S. Pat. Nos. 6,706,181; 6,379,537; 6,101,996; 5,698,098, and 5,516,425. Any of these existing concepts could be incorporated into the top-side of an engine to overcome the limitations previously described in this disclosure, but cartridge filters have their own limitations (discussed further below) and there are other advantages in using the spin-on filter of this invention over the cartridge type filter described in these patents.  
         [0007]     While the cartridge filter element itself is relatively inexpensive, other features that are provided integrally with a spin-on filter must be provided separately in the filter housing when using a cartridge type filter. These features include element support to prevent paper collapse, bypass function for when the element is plugged or the oil is very cold and viscous (to prevent oil starvation to the engine bearings), element sealing to provide a proper oil flow path, a structure that can withstand the operating pressure of the oil lubrication system, and a drain valve for removal of oil within the filter assembly when servicing the filter element. Utilizing a low cost spin-on filter to provide these features puts the design complexity into the filter itself and allows the housing unit design to be simple and low cost.  
       BRIEF SUMMARY OF THE INVENTION  
       [0008]     The Applicants have found that mounting a spin-on oil filter within a generally cup-shaped housing on top of an engine crankcase allows for easy access to change the filter, without spilling over the engine or ground, and also provides a convenient location to add re-fill oil to the crankcase.  
         [0009]     In one embodiment, the invention is an oil filter housing comprising a lower housing unit, which comprises an at least approximately circular sidewall connected to a bottom surface to form an open-topped chamber, and an upper housing unit. A male threaded portion, adapted to mount a spin-on oil filter, extends up from the bottom surface. A flat gasket surface is located on the bottom surface, wherein the gasket surface is concentric with the sidewall. The housing comprises three passages: (i) a first passage adapted to permit flow of dirty oil to an oil filter mounted on the male threaded portion, wherein the first passage is located in the bottom surface inside the gasket surface; (ii) a second passage adapted to permit flow of filtered oil away from an oil filter mounted on the male threaded portion, wherein the second passage is located in the male threaded portion; and, (iii) a third passage adapted to permit drainage of oil from the open-topped chamber, wherein the third passage is located in the bottom surface outside of the gasket surface. The upper housing unit is removably attached to the lower housing unit, and is adapted to cover the open-topped chamber. The oil filter housing is adapted to allow a spin-on oil filter to be mounted in a normally inverted position on or above a top side of an internal combustion engine. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     Preferred embodiments of the invention are described below with reference to the accompanying drawings, which are for illustrative purposes only. Throughout the following views, reference numerals will be used in the drawings, and the same reference numerals will be used throughout the several views, and in the description, to indicate same or like parts or steps.  
         [0011]      FIG. 1  shows a side elevation view of the lower housing unit.  
         [0012]      FIG. 2  shows a top plan view of the lower housing unit.  
         [0013]      FIG. 3  is a top oblique view of the upper housing unit.  
         [0014]      FIG. 4  shows a cross-sectional view of the assembled oil filter assembly.  
         [0015]      FIG. 5  shows the oil filter assembly mounted on a horizontal crankshaft engine.  
         [0016]      FIG. 6  shows the mounted oil filter assembly of  FIG. 5  with the upper housing removed to expose the oil filter.  
         [0017]      FIG. 7  shows the mounted oil filter assembly of  FIG. 5  with both the upper housing and the oil filter removed.  
         [0018]      FIG. 8  shows the oil filter assembly mounted on a vertical crankshaft engine.  
         [0019]      FIG. 9  shows the mounted oil filter assembly of  FIG. 8  with the upper housing removed to expose the oil filter.  
         [0020]      FIG. 10  shows the mounted oil filter assembly of  FIG. 8  with both the upper housing and the oil filter removed. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]     In at least some embodiments, the invention consists of a two-piece, roughly cylindrical housing, having lower and upper housing units that are constructed of plastic, aluminum, or other such appropriate material. The lower housing unit can be integrally formed with the engine crankcase, or can be a separate component that mounts to the engine crankcase (the design shown is separately mounted). The bottom surface of the lower housing unit consists of a male threaded portion extending up from the bottom surface (to mount the spin-on oil filter) and a concentric flat gasket surface (for the spin-on filter gasket to seal against). The lower housing unit has either threaded or quarter-turn type details on the outside wall to facilitate connection with the upper housing unit (quarter-turn details are shown).  
         [0022]     Spin-on oil filters are well-known in the art. One end of the filter has a threaded hole to engage with spin-on mounts, as well as openings to allow ingress and egress of oil. This end is considered the “top” end of the filter.  
         [0023]     The lower housing unit contains a total of three oil passages communicating with the bottom surface of the lower housing unit. Two passages are located inside the filter gasket surface portion of the lower housing unit: the first is a passage bringing dirty oil to the filter (through the hole located just inside of the gasket surface) and the second a passage returning cleaned oil to the engine lubrication system (through the hole located in the male threaded portion). A drain passage is located near the outer wall of the lower housing unit, connecting to the interior of the engine crankcase and allowing any oil in the lower housing unit (outside of the oil filter gasket) to drain back into the engine crankcase.  
         [0024]     The upper housing unit is essentially a cover to the lower housing unit, containing either threaded or quarter-turn type details to mate with the lower housing unit (quarter-turn shown). The upper housing unit is preferably larger in diameter than the lower housing unit, and overlaps a significant portion of the lower housing unit sidewalls. A sealing element is positioned between the upper and lower housing unit sidewalls to keep any oil contained within the housing assembly. Preferred embodiments of the invention are described in more detail below.  
         [0025]     The oil filter assembly  2  is shown in  FIGS. 1-10 . As shown in  FIGS. 1-3 , the oil filter assembly  2  includes a lower housing unit  4  and an upper housing unit  6 .  FIG. 1  shows a side elevation view of the lower housing unit  4 , while  FIG. 2  shows a top plan view of the lower housing unit. The lower housing unit  4  includes a cup-shaped portion  8  with an open upper end  10  and a closed lower end  12 . Additionally, extending downward below the cup-shaped portion  8  are first, second and third supports  14 ,  16  and  18 , respectively. The supports  14 ,  16 ,  18  are rejoined to one another at a base  20  of the lower housing unit  4 , which includes a bolt hole  5  by which the assembly  2  can be mounted on an engine crankcase (see  FIGS. 5-10 ). In an alternative embodiment, lower housing unit  4  can be formed integrally with the crankcase and one or more of supports  14 ,  16 ,  18  might be eliminated.  
         [0026]     As shown in  FIG. 3 , the upper housing unit  6  is a cup-shaped cover that can be fitted over the cup-shaped portion  8  of the lower housing unit  4  so as to close the open upper end  10 . In the embodiment shown, the upper housing unit  6  includes two slots or “quarter turn details”  22  (one of which is shown in  FIG. 3 ) that are configured to interface and receive two complementary cylindrical protrusions  24  extending outward from opposite sides of the cup-shaped portion  8  of the lower housing unit  4 . When appropriately placed over the lower housing unit  4  and rotated, the upper housing unit  6  is locked onto the lower housing unit due to the interaction of the quarter turn details  22  and cylindrical protrusions  24  in combination with an internal spring  25  (discussed further below). In alternate embodiments, the upper housing unit  6  and lower housing unit  4  could have female and male threads, respectively, allowing the upper housing unit to be screwed onto the lower housing unit.  
         [0027]     Referring additionally to  FIG. 4 , a cross-sectional view of the oil filter assembly  2  when fully assembled is provided. As shown, the assembly  2  includes an annular spin-on oil filter  26  supported within the housing units  4 , 6 . Also, a sealing element (e.g., an  0 -ring)  28  is positioned between interfacing cylindrical surfaces of the lower and upper housing units  4 , 6  so as to keep oil from leaking out of the assembly  2  between those units. The filter  26  is supported in an inverted manner, i.e., top end down with a sealed portion of an inner cylindrical surface  30  being in contact with a tubular boss or protrusion  32  extending from the closed lower end  12  of the cup-shaped portion  8  of the lower housing unit  4 . A further annular seal  36  extends circumferentially around the tubular protrusion  32  and is in axial contact with a circular ridge  34  also protruding upward from the closed lower end  12  of the cup-shaped portion  8 . The ridge  34  serves as a gasket sealing surface and is substantially perpendicular to the tubular protrusion  32 .  
         [0028]     As discussed above, the filter  26  is a spin-on filter and, as such, the sealed portion of the inner cylindrical surface  30  has female threads that interface complementary male threads on the tubular protrusion  32  (the threads are not shown in  FIG. 4 ). With such a design, the spin-on filter can easily be coupled to the lower housing unit  4 , simply by rotating the filter onto the protrusion  32 . Also as shown in  FIG. 4 , the spring  25  discussed above is positioned between the top of the upper housing unit  6  and the top of the filter  26 . The spring  25  tends to push the upper housing unit  6  away from the lower housing unit  4 , thereby causing the quarter turn details  22  and protrusions  24  to become positioned so as to prevent relative rotational movement of the upper and lower housing units and to keep those housing units locked together.  
         [0029]     Further as shown in  FIG. 4 , the respective supports  14 ,  16  and  18  contain an unfiltered oil passage  44 , a filtered oil passage  46  and a drain passage  48 , respectively. The unfiltered oil passage  44  provides a channel by which unfiltered oil is communicated from the base  20  (and the engine) to an annular space  38  existing between the tubular protrusion  32  and the annular seal  36 /circular ridge  34 . The unfiltered oil provided to the annular space  38  further then proceeds into the interior of the filter by way of multiple holes  40 . Upon being filtered, the oil then proceeds into an interior cavity within the filter defined by the inner cylindrical surface  30  and subsequently into the filtered oil passage  46 , which begins at the top of the tubular protrusion  32  and continues down to (or nearly to) the base  20 , ending above the bolt hole  5 . The filter media and interior flow paths of the filter are not shown but are well-known in the art.  
         [0030]      FIG. 4 , and the above descriptions, are for filtered and unfiltered oil paths that follow the normal convention. If a spin-on filter was available with reversed flows, the invention would work equally as well.  
         [0031]     To the extent that oil may leak between the annular seal  36  and circular ridge  34 , from the annular space  38  to an exterior region  42  existing between the housing units  4 , 6  and the filter  26 , such oil is communicated into the drain passage  48 . Upon reaching the drain passage  48 , the oil is further communicated back to the engine crankcase or to another appropriate place, such as a drain pan.  FIG. 4  shows ends  50  of the passages  44 ,  46  and  48  at or proximate to the base  20  where the passages are coupled to corresponding passages of the engine. In the present embodiment, because the drain passage  48  is positioned along the side of the lower housing unit  6 , the die used to create the drain passage is inserted from the bottom of the lower housing unit rather than the top (as in the cases of the passages  44 , 46 ). Consequently,  FIG. 4  also shows a plug  52  to be inserted at the bottom of the drain passage  48  to plug a location where the die was inserted. The ends  50  are formed separately from the remaining portions of the passages  44 ,  46 , and  48  and extend generally outward from the page as viewed in  FIG. 4 .  
         [0032]     Turning to  FIGS. 5-10 , the oil filter assembly  2  is shown to be implemented in conjunction with two different engines. In particular,  FIGS. 5-7  show the oil filter assembly  2  to be mounted on a horizontal crankshaft engine  54 , while  FIGS. 8-10  show the assembly to be mounted on a vertical crankshaft engine  56 . In each case, the oil filter assembly  2  is shown to be mounted in such a manner that cup-shaped portion  8  of the lower housing unit  4  and the upper housing unit  6  are positioned at or above the top of the engine to allow for easy access to the oil filter assembly, for maintenance purposes (e.g., filter replacement and oil changing) or otherwise. In particular,  FIGS. 6 and 9  show the oil filter assembly  2  with the upper housing unit  6  removed, while  FIGS. 7 and 10  show the oil filter assembly with both the upper housing unit and the oil filter  26  removed.  
         [0033]     The design of the oil filter assembly  2 , and the location of the oil filter assembly relative to the engine on which it is mounted, in particular facilitate the changing of oil and the changing of the oil filter without spilling oil (on the engine or on the ground) in the process. Oil within the spin-on filter  26  that is released upon the opening of the upper housing unit  6  and unscrewing of the spin-on filter merely proceeds into the drain passage  48  and into the engine. Oil can also be easily added to an engine, either with the filter removed, or with the filter in place, for example, by pouring oil over the filter and allowing the oil to drain into the drain passage. Use of the oil filter assembly for addition of refill oil can be facilitated if the sidewall of the cup-shaped portion  8  is eccentric to the filter and/or has a non-circular cross-section. Such eccentricity or non-circularity will result in a region having a larger clearance between the filter and the sidewall, thereby providing a convenient location to pour in the refill oil.  
         [0034]     This invention provides for a more readily accessible mounting location on an internal combustion engine for a spin-on type oil filter, and a means for service (removal) of that spin-on type oil filter without spilling any oil (on the engine or on the ground) in the process. Further, the invention allows for improved installation of a new spin-on oil filter without use of tools, and without potential long-term leakage of oil (on the engine or on the ground) due to improper tightening of the filter (any leakage past the spin-on filter gasket will be returned to the engine crankcase via the drain passage). Still further, the invention can be used as the primary engine oil fill (with the filter removed for oil change or with the filter in place for adding small amounts of oil between changes).  
         [0035]     It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein, but include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims.