Abstract:
The engine/transmission assembly includes a first chamber, a second chamber, and a fill hole that fluidly communicates with the first chamber. The first chamber is capable of containing lubricant at a first level, and the second chamber is capable of containing lubricant at a second level. The engine/transmission assembly also includes an opening that is between the first and second chamber and that fluidly communicates with the first and second chamber. The opening is positioned to maintain the first level in the first chamber and raise the second level in the second chamber when lubricant is added to the first chamber through the fill hole, and to maintain these two levels when the engine is running.

Description:
[0001]    This application claims the benefit of prior filed co-pending provisional patent application No. 60/351,806 filed on Oct. 26, 2001. 
     
    
     
         [0002]    FIELD OF THE INVENTION  
           [0003]    The invention relates to powertrains including an engine and a transmission, and more particularly to lubrication systems for powertrains.  
         BACKGROUND OF THE INVENTION  
         [0004]    Known powertrains generally include a crankshaft chamber that contains a crankshaft and a clutch chamber that contains a clutch assembly. The crankshaft chamber and the clutch chamber are either totally separate compartments or compartments that allow fluid communication of the lubricant.  
           [0005]    Totally separate chambers include separate fill holes used to introduce lubricant into each of the separate chambers and separate dipsticks used to measure the amount of lubricant within each of the separate chambers. Powertrains that contain separate chambers are disadvantageous because multiple fill holes and dipsticks increase manufacturing costs and require the operator to check and fill multiple chambers thereby increasing maintenance time and expense.  
           [0006]    Known fluidly connected chambers include holes that are positioned between the chambers to maintain the common lubricant at the same level in each chamber. These types of engines are disadvantageous because the level of the lubricant in the crankshaft chamber should be maintained below the crankshaft for efficient operation, however this level is inadequate to provide sufficient lubrication for the clutch assembly in the clutch chamber.  
         SUMMARY OF THE INVENTION  
         [0007]    The engine/transmission assembly or powertrain of the present invention efficiently operates the crankshaft above the level of the lubricant in the crankshaft chamber and sufficiently lubricates the clutch assembly in the clutch chamber by positioning an overflow opening between the crankshaft chamber and the clutch chamber to maintain the level of lubricant in the clutch chamber at a level that is above the level of the lubricant in the crankshaft chamber.  
           [0008]    The lubrication system decreases the manufacturing costs of the engine/transmission assembly and reduces the maintenance time required to maintain the proper fill level of lubricant by eliminating the need for separate lubricant fill holes and dipsticks. The proper fill level is obtained by measuring the fill level of the lubricant in the crankshaft chamber and by supplying lubricant to the clutch chamber through a single fill hole.  
           [0009]    One embodiment of the present invention is directed to an engine/transmission assembly that includes a first chamber, a second chamber, and a fill hole that fluidly communicates with the first chamber. The first chamber is capable of containing lubricant at a first level, and the second chamber is capable of containing lubricant at a second level. The engine/transmission assembly also includes an opening that is between the first and second chamber and that fluidly communicates with the first and second chamber. The opening is positioned to maintain the first level in the first chamber and raise the second level in the second chamber when lubricant is added to the first chamber through the fill hole.  
           [0010]    Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is a side view illustrating an engine/transmission assembly embodying the present invention.  
         [0012]    [0012]FIG. 2 is a partial cross section view taken along line  2 - 2  in FIG. 1, illustrating a chain tower of the engine/transmission assembly.  
         [0013]    [0013]FIG. 3 is a cross section view taken along line  3 - 3  in FIG. 2, illustrating a clutch chamber of the engine/transmission assembly.  
         [0014]    [0014]FIG. 4 is a partial cross section view taken along line  4 - 4  in FIG. 1, illustrating an overflow opening and a dipstick of the engine/transmission assembly.  
         [0015]    [0015]FIG. 5 is a partial cross section view taken along line  5 - 5  in FIG. 1, illustrating a drain hole of the engine/transmission assembly.  
         [0016]    [0016]FIG. 6 is a partial cross section view taken along line  6 - 6  in FIG. 1, illustrating a fill hole of the engine/transmission assembly.  
         [0017]    [0017]FIG. 7 is a schematic view illustrating the operation of the engine/transmission assembly shown in FIG. 1. 
     
    
       [0018]    Before one embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The use of “consisting of” and variations thereof herein is meant to encompass only the items listed thereafter. The use of letters to identify elements of a method or process is simply for identification and is not meant to indicate that the elements should be performed in a particular order.  
       DETAILED DESCRIPTION  
       [0019]    [0019]FIG. 1 illustrates an engine/transmission assembly  10  of the present invention. The engine/transmission assembly  10  includes a housing  12  and an engine  14  including a cylinder housing  16 , a cylinder head  18 , and a cylinder head cover  20 .  
         [0020]    In further reference to FIG. 4, the housing  12  includes a first side  24  that includes an outboard wall  26  and a curved outer wall  28  that extends from the perimeter of the outboard wall  26  and that is substantially perpendicular to the outboard wall  26 . A forward portion  30  of the outer wall  28  is configured to partially define a cylinder bore  32  (FIG. 2). The first side  24  also includes a lubricant filter cavity  34  that houses a lubricant filter  35  (shown schematically in FIG. 7) which is capable of removing contaminates from a lubricant  36 .  
         [0021]    The housing  12  also includes a second side  38  that includes an outer wall  40 . A forward portion  42  of the outer wall  40  is configured to partially define the cylinder bore  32  (FIG. 2), and the outer wall  40  includes a chain cavity  44  (FIGS. 2 and 3).  
         [0022]    The second side  38  also includes a dividing wall  46  that extends approximately perpendicularly from the outer wall  40  and that divides the outer wall  40  into first and second portions  48 ,  50 . The dividing wall  46  includes an overflow opening  52 , and the second portion  50  of the outer wall  40  includes a drain hole  54  that is capable of draining a lubricant  36  (FIG. 5).  
         [0023]    The housing  12  also includes a second side cover  56  that has an outboard wall  58  and an outer wall  60  that extends from the perimeter of the outboard wall  58  and that is substantially perpendicular to the outboard wall  58 . As shown in FIG. 6, the outboard wall  58  also includes a lubricant fill hole  62  that opens substantially upwardly to allow a lubricant  36  to be poured into the lubricant fill hole  62 . The lubricant fill hole  62  includes internal threads  64  to threadingly engage with external threads  66  on an lubricant fill hole cap  68 . The outboard wall  58  also includes a projection, or sight blocker  70  that extends from the outboard wall  58 . The sight blocker  70  is positioned below the lubricant fill hole  62  and above lubricant level  198  to obstruct the view of the lubricant level  198  through the fill hole  62 .  
         [0024]    The configuration of the housing  12  is not limited to the illustrated embodiment and can vary without departing from the scope of the present invention.  
         [0025]    Referring back to FIG. 4, the outboard wall  58  also includes a dipstick housing  72  that extends toward the bottom of the outboard wall  58  and into the outer wall  60  of the second side cover  56 . The dipstick housing  72  includes internal threads  74  that threadingly engage external threads  76  of a dipstick  78  that extends through a substantial portion of the dipstick housing  72 .  
         [0026]    With specific reference to FIGS. 4 and 5, the second side  38  and the second side cover  56  are fastened together such that a gasket (not shown) is coupled between an adjacent face  80  of the outer wall  60  of the second side cover  56  and an adjacent face  82  of the first portion  48  of the outer wall  40  of the second side  38  to form a first, or clutch chamber  84 . The clutch chamber  84  is defined by the outboard wall  58  of the second side cover  56 , the dividing wall  46 , the first portion  48 , and the outer wall  60  of the second side cover  56 . The clutch chamber  84  is in fluid flow communication with the drain hole  54 , the fill hole  62 , the overflow opening  52 , and the chain cavity  44 .  
         [0027]    The first side  24  and the second side  38  are fastened together such that a gasket (not shown) is coupled between an adjacent face  86  of the outer wall  28  of the first side  24  and an adjacent face  88  of the second portion  50  of the outer wall  40  of the second side  38  to form a second, or crankshaft chamber  90 . The crankshaft chamber  90  is defined by the outboard wall  26  of the first side  24 , the dividing wall  46 , the second portion  50 , and the outer wall  28  of the first side  24 . The crankshaft chamber  90  is in fluid flow communication with the drain hole  54 , the overflow opening  52 , the cylinder bore  32 , and the dipstick housing  72  through a passageway  91  that is positioned in the first portion  48  of the outer wall  40  of the second side  38  and adjacent to the clutch cavity. The drain hole  54  includes internal threads  92  that are removably threadingly engaged with external threads  94  on a drain plug  96 . When the drain plug  96  is inserted into the drain hole  54  the drain plug  96  blocks the clutch and crankshaft chamber  84 ,  90  from being fluidly connected with each other and with the drain hole  54 .  
         [0028]    Referring to FIG. 2, the cylinder housing  16  includes the cylinder bore  32 , cooling fins  102 , and the chain cavity  44 . The cylinder bore  32  extends through the cylinder housing  16  along a bore axis  106 , and the cooling fins  102  extend perpendicularly from the bore axis  106  from top, bottom, and side faces  108 ,  110 ,  112  of the cylinder housing  16  (FIG. 1).  
         [0029]    The cylinder head  18  includes a cam shaft  116 , rocker arms (not shown), intake and exhaust valves (not shown), and a spark plug  124 . The cam shaft  116  is rotatably mounted to the cylinder head  18  and includes first and second lobes  128 . The cam shaft  116  includes a cam sprocket  130  that is positioned within the chain cavity  44  of the cylinder head  18  and that engages a chain  134 . The rocker arms are pivotably connected to a rocker shaft (not shown) and slidably engage the lobes  128  of the cam shaft  116 . The valves include stems that engage the rocker arms and valve heads  138  that are biased against valve seats in the cylinder head  18 . The cylinder head  18  is connected to the cylinder housing  16  such that the valve heads  138  and the spark plug  124  communicate with a combustion chamber  142  of the cylinder bore  32 .  
         [0030]    The cylinder head cover  20  is connected over the cylinder head  18  for protection and to prevent the lubricant  36  from escaping the engine/transmission assembly  10 . The cylinder head cover  20 , the cylinder head  18 , the cylinder housing  16 , and the housing  12  are connected with elongated bolts (not shown) that extend from the housing  12  through holes (not shown) located in the corners of the cylinder housing  16 , the cylinder head  18 , and the cylinder head cover  20 .  
         [0031]    The engine/transmission assembly  10  as illustrated in FIGS.  4 - 6  includes a crankshaft  144 , a clutch assembly  146 , an intermediate shaft  148 , and an output shaft  150 . As shown in FIG. 5, the crankshaft  144  is rotatably coupled between the outboard wall  26  of the first side  24  and the dividing wall  46  of the second side  38 . The crankshaft  144  is substantially positioned within the crankshaft chamber  90  and includes a crankshaft axis  152 . The crankshaft  144  includes a crank pin  154  that is offset from the crankshaft axis  152 . A connecting rod  158  rotatably connects the crank pin  154  with a piston  160  that is positioned for reciprocal motion in the cylinder bore  32  to rotate the crankshaft  144  (FIG. 2). The crankshaft  144  also includes at one end a pump drive gear  162  that drives a pump  163  (shown schematically in FIG. 7) that distributes lubricant  36  throughout the engine. The other end of the crankshaft  144  extends through the dividing wall  46  and into the clutch chamber  84  where it couples to the clutch assembly  146  and a drive sprocket  164  that drives the chain  134  which engages to the cam sprocket  130 .  
         [0032]    The clutch assembly  146  includes an automatic clutch  166  that is connected to the crankshaft  144  and that is rotatably coupled to the outboard wall  58  of the second side cover  56 . The automatic clutch  166  is positioned within the clutch chamber  84 .  
         [0033]    Referring again to FIG. 4, the intermediate shaft  148  is rotatably coupled to the outboard wall  58  of the second side cover  56  and the outboard wall  26  of the first side  24 . The intermediate shaft  148  extends through the overflow opening  52 . The intermediate shaft  148  includes a first portion  172  positioned within the clutch chamber  84  and a second portion  174  positioned within the crankshaft chamber  90 . The first portion  172  engages the clutch assembly  146  and the second portion engages the output shaft  150 .  
         [0034]    As shown in FIG. 6, the output shaft  150  is rotatably coupled to the dividing wall  46  of the second side  38  and the outboard wall  26  of the first side  24 . The output shaft  150  extends through the outboard wall  26  of the first side  24  and is coupled to an output sprocket  184  that can engage a drive chain  186  which could be used to rotate a wheel of a scooter, for example.  
         [0035]    Prior to running the engine, the clutch chamber  84  and the crankshaft chamber  90  are filled with a lubricant  36  that is used along with a lubrication system  196  (shown schematically in FIG. 7) to lubricate the components of the engine/transmission assembly  10 . Initially, the lubricant fill hole cap  68  is removed and the lubricant  36  is poured into the clutch chamber  84  through the open fill hole  62 . After the clutch chamber  84  is filled up to the level of the overflow opening  52 , the excess lubricant  36  will run through the overflow opening  52  and into the crankshaft chamber  90  to begin filling the crankshaft chamber  90 . The sight blocker  70  prevents the operator from seeing the fill level of the clutch chamber  84  to ensure that the operator uses the dipstick  78  to measure the fill level of the lubricant  36 . If the sight blocker  70  was not present, an operator might incorrectly conclude that both chambers  84 ,  90  are properly filled based on visually confirming that the clutch chamber  84  is filled.  
         [0036]    The operator uses the dipstick  78  to determine the level of lubricant  36  in the crankshaft chamber  90  and adds lubricant  36  to the clutch chamber  84  until the level in the crankshaft chamber  90  is properly within the limits marked on the dipstick  78 . When the lubricant  36  in the crankshaft chamber  90  is within the limits of the dipstick  78 , the lubricant  36  is at the proper fill level. At the proper fill level, the lubricant  36  in the clutch chamber  84  is at the first lubricant level  198  such that the automatic clutch  166  is partially submerged in the lubricant  36 , and the lubricant  36  in the crankshaft chamber  90  is at a second level  200  such that the crankshaft  144  is positioned substantially above the lubricant  36  throughout the rotation of the crankshaft  144 . After the proper fill level is obtained, the lubricant fill cap  68  and dipstick  78  are replaced. The proper fill level as shown in the drawings and as mentioned in the specification and claims is measured when the engine  14  is at rest.  
         [0037]    The operation of the lubrication system  196  is described with reference to FIG. 7. The pump  163 , which is driven by the pump drive gear  162  of the crankshaft  144 , pumps lubricant  36  from the crankshaft chamber  90  and moves the lubricant  36  to the lubricant filter  35  within the lubricant filter cavity  34 . From the lubricant filter cavity  34  the flow of lubricant  36  is split into a first portion  202  that is diverted to the crankshaft  144  and a second larger portion that is diverted to the cylinder head  18 .  
         [0038]    The first portion  202  moves through the outboard wall  26  of the first side  24  to lubricate a bearing  206  of the crankshaft  144  and moves through a hollow passage of the crankshaft  144  to lubricate between the crank pin  154  and connecting rod  158 . The lubricant  36  then exits the bearing  206  and the crank pin  154  and falls to accumulate in the crankshaft chamber  90 .  
         [0039]    In further reference to FIG. 7, the second portion  204  of lubricant  36  moves up through the cylinder housing  16  and the cylinder head  18  by flowing through a clearance between a bolt and bolt hole. Once the second portion  204  of lubricant  36  reaches the cylinder head  18 , the lubricant  36  escapes the hole to lubricate a first cam bearing  208  (FIG. 2). The lubricant  36  then enters into a passageway in the rocker shaft to intermittently lubricate the rocker arms and cam lobes  128 . The lubricant  36  escapes through holes in the rocker shaft and holes in the rocker arms that align when the rocker arms are in a specific position relative to the rocker shaft. The remaining lubricant  36  in the rocker shaft flows across the rocker shaft to lubricate the second cam bearing (not shown).  
         [0040]    After the second portion  204  of lubricant  36  is diverted throughout the cylinder head  18 , it collects in the cam/rocker arm cavity until it overflows into the chain cavity  44  of the cylinder head  18  and down the chain cavity  44  into the clutch chamber  84  (FIG. 3). The clutch chamber  84  will feed excess lubricant  36  into the crankshaft chamber  90  through the overflow opening  52 , and the lubricant  36  will therefore be maintained at the proper levels in the clutch and crankshaft chambers  84 ,  90 .  
         [0041]    Since the overflow opening  52  regulates a constant lubricant level  198  in the clutch chamber  84 , consumed lubricant will affect the lubricant level  200  only in the crankcase chamber  90  where it can be measured by dipstick  78 .  
         [0042]    The invention is not limited to the illustrated powertrain. Different clutch assemblies, valve trains, and lubrication paths can be used without departing from the scope of the present invention.