Abstract:
A lubrication system for an in-line engine which has a piston symmetry plane that is tilted relative to a vertical plane is provided with an oil pan and windage tray that facilitates the transfer of oil from a rotating crankshaft to the oil pan without excessive aeration. In addition, it facilitates the removal of entrained air from liquid oil as it passes from the crankshaft to a pool of oil collected in an oil pan. A windage tray is provided with a louver structure and a louver opening structure that assists this passage of oil droplets without undue aeration being caused.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is generally related to a lubrication system for a marine engine and, more particularly, to an oil pan and windage tray for a marine engine that is tilted to lower its overall height. 
     2. Description of the Related Art 
     Many different types of marine propulsion systems are known to those skilled in the art. One type of sterndrive propulsion system is known which incorporates a tilted in-line engine which lowers the profile of the engine and facilitates its use in certain types of marine vessels, such as bass boats, which heretofore were not amenable to the use of sterndrive propulsion systems. 
     U.S. Pat. No. 4,519,348, which issued to Hamilton on May 28, 1985, describes an oil pan and windage tray for high performance engines which reduce friction loss by separating the oil collection volume of the pan from rotating engine components. A skimmer integral with the tray skims oil from rotating parts and channels oil thrown from the rotating parts into a side pouch of the pan for delivery to the pan collection volume. The skimmer and tray mount to the engine separately from the pan. An alternate embodiment of a dry sump pan has a removable partition between a side pouch and the rotating parts and a skimmer separate from the pan. 
     U.S. Pat. No. 6,019,071, which issued to Maciejka on Feb. 1, 2000, describes an engine windage tray. The windage tray is positioned between the crankshaft and the oil pan. It includes a passage having an inlet port receiving the pressurized oil and a first outlet port directing a first stream of the pressurized oil at the piston. In a preferred embodiment, the passage further includes a second outlet port directing a second stream of pressurized oil at the piston. 
     U.S. Pat. No. 6,530,354, which issued to Bishop et al. on Mar. 11, 2003, describes an oil pan with vertical baffles. The oil pan is intended for use with an engine having a crankshaft and includes a pan body adapted to be disposed beneath the crankshaft for receiving oil that is exhausted from the engine. The oil pan further includes a vertically extending baffle attached to the pan body. 
     U.S. Pat. No. 6,874,460, which issued to Duwel on Apr. 5, 2005, describes an integrated oil pan and windage tray. The tray is adapted for installation between the engine block and the oil pan and the tray has a body with a peripheral flange extending about the periphery of the body and at least one deflector portion extending away from the body to a location spaced away from the peripheral flange. 
     U.S. Pat. No. 7,014,519, which issued to Batten et al. on Mar. 21, 2006, discloses a marine propulsion system with a tilted in-line engine. The engine is disposed at a tilted angle relative to a vertical plane in order to reduce the maximum height requirement space of an engine compartment of a marine vessel. The crankshaft axis of the in-line engine can be located on a vertical vessel symmetry plane or can be offset from it. The crankshaft of the in-line engine can be disposed parallel to the vessel symmetry plane, within the vessel symmetry plane, or perpendicular to the vessel symmetry plane. 
     The patents described above are hereby expressly incorporated by reference in the description of the present invention. 
     When a marine engine is tilted, as disclosed in U.S. Pat. No. 7,014,519, the physical relationships between the crankshaft of the engine and the liquid oil within the oil sump portion of an oil pan are changed. These physical relationships can result in certain disadvantageous conditions, such as aeration of the liquid oil within the oil pan. If a significant amount of air is suspended within the liquid oil in the oil reservoir of the engine, the lubricity of the oil can be degraded sufficiently to adversely affect the wear of various sliding engine parts. It would therefore be significantly beneficial if an oil storage and collection system of a tilted in-line marine engine could be provided with an arrangement that decreases the aeration of oil stored within the lubrication system while also decreasing the adverse efficiency effect caused by a mist of oil vapor and droplets in the vicinity of rotating components of the engine, such as the crankshaft, connecting rods, and counterweights. 
     SUMMARY OF THE INVENTION 
     A lubrication system for an engine of a marine vessel, made in accordance with a preferred embodiment of the present invention, comprises an internal combustion engine having all of its cylinders aligned in a piston symmetry plane. The piston symmetry plane is disposed at a tilt angle from a vertical plane. The tilt angle is preferably between fifteen and seventy five degrees and the engine has a crankshaft which is disposed within a crankcase and also disposed within the piston symmetry and vertical planes. An oil pan, in a preferred embodiment of the present invention, is attached to the internal combustion engine. The oil pan and the crankcase define an internal cavity. The oil pan is shaped to contain a quantity of liquid oil having an upper oil surface. A windage tray is disposed within the internal cavity. The windage tray has a louver structure formed through a surface thereof. The louver structure is formed to define a louver opening structure therethrough. The louver structure is configured to inhibit droplets of oil from having a direct linear path through the louver opening structure from the crankshaft to the upper oil surface. 
     The oil pan has an internal wall surface which is disposed above the upper oil surface during normal operation of the internal combustion engine. The louver structure is configured to define a direct path through the louver opening structure from the crankshaft to the internal wall surface disposed above the upper oil surface. 
     The oil pan is attached to the internal combustion engine along an attachment surface which is generally perpendicular to the piston symmetry plane. The lowest point of the attachment surface is disposed above the upper oil surface in a particularly preferred embodiment of the present invention. A preferred embodiment of the present invention can further comprise at least one baffle disposed on an internal surface of the oil pan. It can also comprise an oil pick-up conduit disposed in fluid communication with the quantity of liquid oil in the oil pan. 
     The louver structure can comprise first and second louvers spaced apart from each other and the louver opening structure can comprise first and second louver openings. The first and second louver openings are unequal in effective area in a particularly preferred embodiment of the present invention. The first louver opening is larger in effective area than the second louver opening. The internal wall surface is generally parallel to the piston symmetry plane in a particularly preferred embodiment of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be more fully and completely understood from a reading of the description of the preferred embodiment in conjunction with the drawings, in which: 
         FIG. 1  is a front view of a tilted in-line marine engine; 
         FIG. 2  is a section view of the engine shown in  FIG. 1 ; 
         FIG. 3  is an enlarged portion of the illustration in  FIG. 2 ; 
         FIG. 4  shows the oil pan, windage tray, and pick-up conduit of a preferred embodiment of the present invention; 
         FIG. 5  is an exploded isometric view of the illustration in  FIG. 4 ; and 
         FIG. 6  is an enlarged view of an oil pan and pick-up tube made in accordance with a preferred embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Throughout the description of the preferred embodiment of the present invention, like components will be identified by like reference numerals. 
       FIG. 1  is a front view of a marine propulsion engine  10  which is configured as a tilted in-line engine. The basic concept of the tilted in-line engine is generally similar to that which is disclosed in U.S. Pat. No. 7,014,519. It should be understood that the engine  10  can be tilted either toward port or is starboard in various embodiments of the concept disclosed in U.S. Pat. No. 7,014,519 and herein. 
     The engine in  FIG. 1  is shown relative to a bottom portion  12  of a marine vessel. The front view in  FIG. 1  shows the engine  10  with its piston symmetry plane  16  tilted toward the port side of the marine vessel. All of the cylinders of the engine  10  are aligned in the piston symmetry plane  16  which, as illustrated in  FIG. 1 , is disposed at a tilt angle θ from a vertical plane  20 . The tilt angle θ is between fifteen and seventy five degrees in a particularly preferred embodiment of the present invention. The engine  10  has a crankshaft which is rotatable about the crankshaft axis  24 . The crankshaft, which will be described in greater detail below, is disposed within a crankcase and also disposed within the piston symmetry and vertical planes,  16  and  20 . An oil pan  30  is attached to the internal combustion engine  10 . The oil pan  30  and crankcase define an internal cavity, which will be described in greater detail below. The oil pan  30  is shaped to contain a quantity of liquid oil having an upper oil surface. 
       FIG. 2  is a section view taken through the engine  10  to illustrate the crankcase  40  and the internal space  44  of the oil pan  30  which combine to define the internal cavity of the lubrication system described above. Also shown in  FIG. 2  is a counterweight  50  of the crankshaft, which is rotatable about crankshaft axis  24 , a connecting rod  52  and a piston  54  which are all shown in an exemplary fashion to illustrate the relative positions of these components of the engine. Arrow R illustrates the direction of rotation of the crankshaft about its axis  24 .  FIG. 2  also shows the tilt angle θ between the vertical plane  20  and the piston symmetry plane  16 . Line  60  illustrates the typical location of an upper oil surface of the liquid oil stored within the oil pan  30 . A windage tray  70  is disposed within the internal cavity which comprises cavities  40  and  44 . A louver structure  74  is formed through a surface  76  of the windage tray  70 . The louver structure  74  is configured to define a louver opening structure  78 . The louver structure  74  is also configured to inhibit droplets of oil from having a direct linear path through the louver opening structure  78  from the crankshaft to the upper oil surface  60 . 
       FIG. 3  is an enlarged partial view of the illustration shown in  FIG. 2 . With reference to  FIGS. 1-3 , the illustration in  FIG. 3  is intended to more clearly show the louver structure  74  and louver opening structure  78  illustrated in  FIG. 2 . Arrows D are intended to illustrate the likely path of the oil mist and droplets that rotate about the crankshaft as a result of the rotation of the crankshaft structure in the direction represented by arrow R. This mist comprises both liquid oil and oil vapor that are carried on the crankshaft components and thrown from the crankshaft structure as a result of the centrifugal forces caused by its rotation. 
     With continued reference to  FIGS. 1-3 , the louver structure  74  is illustrated in  FIG. 3  as comprising three louvers,  81 - 83 . These louvers are spaced apart from each other to define three louver openings,  91 - 93 . The first louver opening  91  is larger in effective area than the second louver opening  92 . Similarly, the second louver opening  92  is larger in effective area than the third louver opening  93 . Arrows  101 - 103  are provided to illustrate the probable path of oil droplets that are allowed to pass through the three louver openings,  91 - 93 . Oil droplets passing in other directions would likely be blocked, or at least inhibited, from passing from the region identified by reference numeral  40  to the region identified by reference numeral  44  in  FIG. 2 . In other words, to pass through the windage tray  70 , the droplets must follow a trajectory that is generally similar to one of the arrows,  101 - 103 . 
     In  FIGS. 2 and 3 , reference numeral  110  is used to identify an internal wall surface within the oil pan  30 . The internal wall surface  110  is illustrated as being generally parallel to the piston symmetry plane  16 . It is the intent of the present invention, in a preferred embodiment, to restrict the flow of oil droplets through the louver opening structure  74  to paths which are likely to cause the droplets to impinge against the internal wall surface  110  above the surface of liquid oil  60 . As a result, the oil droplets impinging against the oil wall surface  110  will tend to collect on that wall surface above the upper surface  60  of liquid oil and then flow downwardly under the influence of gravity into the pool of liquid oil at the bottom portion of the oil pan  30 . This process will transfer the oil from the crankshaft to the pool of oil in the oil pan  30  in a way that minimizes the aeration of the oil and, in fact, allows entrained air to escape from the liquid oil as it flows downwardly along the inner wall surface  110  toward the upper surface  60  of the oil pool. 
     With continued reference to  FIGS. 1-3 , the oil pan  30  is attached to the internal combustion engine  10  along an attachment surface which is identified by line  120  in  FIG. 3 . It should be understood that the attachment surface of the oil pan  122  is generally perpendicular to the piston symmetry plane  16 . In the embodiment of the present invention illustrated specifically in  FIGS. 2 and 3 , a flange of the windage tray  70  is disposed between parallel attachment surfaces of the oil pan  30  and the crankcase housing  126 . The lowest point  132  of this attachment surface  122  of the oil pan  30  is disposed above the upper oil surface  60  of the liquid oil contained within the oil pan  30  in a preferred embodiment of the present invention. 
       FIG. 4  is an isometric view of the oil pan  30 , the windage tray  70 , and an oil pick-up tube  130 . As can be seen, four rows of louvers are shown formed in the surface  76  of the windage tray  70 . Each row of louvers is intended to be located proximate the circular path of a connecting rod  52  of the engine. In a four cylinder in-line engine, the overall configuration of louvers would appear as shown in  FIG. 4  in a preferred embodiment of the present invention. The varying sizes of the louvers in the different rows in  FIG. 4  are a result of spatial considerations which are not directly related to the basic concepts of the present invention. The is pick-up tube  130  has one end (not shown in  FIG. 4 ) disposed within the pool of oil below the upper surface  60  and another end  140  connected in fluid communication with an oil pump which draws oil from the oil pool below the upper surface  60  and causes that oil to flow to various locations where lubrication is needed for the engine. A support structure  146  is provided to support the weight of the pick-up tube  130 . 
       FIG. 5  is an exploded isometric view of the structure shown in  FIG. 4 . In  FIG. 5 , a plurality of baffles,  151 - 155 , are disposed on a lower internal surface  160  of the oil pan  30 . These baffles direct the flow of liquid oil toward the lower end  146  of the pick-up tube  130 . This allows an oil pump to draw the liquid oil from the lowermost portion of the pool of oil within the oil pan  30 . The pick-up tube  130  extends through the opening identified by reference numeral  160  in  FIG. 5 . 
     With reference to  FIGS. 4 and 5 , it can be seen that the louvers,  81 - 83 , are configured to result in louver openings,  91 - 93 , of different effective areas. As described above, these louver openings,  91 - 93 , are positioned to direct a flow of oil droplets and mist in the directions identified by reference numerals  101 - 103  in  FIG. 3  and toward the inner wall surface  110  of the oil pan  30 . 
       FIG. 6  is an enlarged section view of the oil pan  30  of the present invention, showing the pick-up tube  130  and the position of its end  146  that is disposed within the oil pool below the upper surface  60 .  FIG. 6  also shows a drain opening  170  that can be used to remove oil from the oil pan  30 . 
     With reference to  FIGS. 1-6 , it can be seen that a preferred embodiment of the present invention comprises an internal combustion engine  10  having all of its cylinders aligned in a piston symmetry plane  16 . The piston symmetry plane  16  is disposed at a tilt angle θ from a vertical plane  20 . The tilt angle θ is between fifteen and seventy five degrees in a preferred embodiment of the present invention. The engine  10  has a crankshaft disposed within a crankcase  40  and disposed within the piston symmetry and vertical planes,  16  and  20 . An oil pan  30  is attached to the internal combustion engine  10 . The oil pan and the crankcase define an internal cavity which is represented by reference numerals  40  and  44  in  FIG. 2 . The oil pan  30  is shaped to contain a quantity of liquid oil in a pool having an upper oil surface  60 . A windage tray  70  is disposed within the internal cavity and has a louver structure  74  formed through a surface  76  thereof. The louver structure  74  is formed to define a louver opening structure  78  therethrough. The louver structure  74  is configured to inhibit droplets, represented by arrows D, of liquid oil from having a direct linear path through the louver opening structure  78  from the crankshaft to the upper oil surface  60 . The oil pan  30  has an internal wall surface  110  disposed above the upper oil surface  60  during normal operation of the internal combustion engine  10 . The louver structure  74  is configured to define a direct path, represented by arrows  101 - 103 , through the louver opening structure  78  from the crankshaft to the internal wall surface  110  disposed above the upper oil surface  60 . The oil pan  30  is attached to the internal combustion engine  10  along an attachment surface, identified by reference numerals  120  and  122  in  FIG. 3 , which is generally perpendicular to the piston symmetry plane  16 . The lowest point  132  of the attachment surface  122  is disposed above the upper oil surface  60  in a preferred embodiment of the present invention. At least one baffle,  151 - 155 , is disposed on an internal surface  160  of the oil pan  30 . An oil pick-up conduit  130  is disposed in fluid communication with the quantity of liquid oil below the upper surface  60 . The louver structure  74  comprises first, second and third louvers,  81 - 83 , which are spaced apart from each other and the louver opening structure  78  comprises first, second and third louver openings,  91 - 93 . The louver openings are unequal in effective area through which oil droplets can pass. For example, the effective area of the first louver opening  91  is greater than that of the second louver opening  92  and the effective area of the second louver opening  92  is greater than that of the third louver opening  93 . The internal wall surface  110  is generally parallel to the piston symmetry plane  16  in a preferred embodiment of the present invention. 
     Although the present invention has been described in particular detail and illustrated to show a preferred embodiment, it should be understood that alternative embodiments are also within its scope.