Patent Abstract:
A crankshaft has a receiving platform for catching lubricant dropping from a main bearing assembly. The receiving platform has at least one wall disposed thereon. The wall has one point that is the furthest from the rotational axis of the crankshaft. One channel is defined in the platform and has an inlet disposed close to the point of the wall that is furthest from the rotational axis of the crankshaft. The channel has an outlet in the vicinity of a connecting rod bearing assembly, so that lubricant dropped on the receiving platform will flow to the connecting rod bearing assembly.

Full Description:
CROSS-REFERENCE 
       [0001]    The present application claims priority to U.S. Provisional Application No. 61/426,811, filed Dec. 23, 2010, the entirety of which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to a crankshaft for a two-stroke engine and to a two-stroke engine comprising such crankshaft. 
       BACKGROUND 
       [0003]    As with other types of internal combustion engines, two-stroke engines comprise a crankshaft disposed in a crankcase for converting the linear movement of the engine&#39;s piston, or pistons, into rotating torque. The crankshaft usually comprises a crankshaft body made of a single piece of hard material, such as steel, and the main components of the crankshaft are integrally formed with the crankshaft body. In some instances, the crankshaft body may also be made of parts connected together by various means known in the art. The crankshaft is rotatably connected to the crankcase via a plurality of main bearing assemblies, and rotatably connected to the connecting rods transmitting the energy generated by the pistons via connecting rod bearing assemblies. Since the crankshaft usually rotates at high speed within the crankcase, the various bearing assemblies connected thereto, including the connecting rod bearing assemblies, need to be appropriately lubricated. 
         [0004]    Two-stroke engines do not generally have sophisticated pressurized lubrication systems for lubricating all the various components of the crankshaft and the various components connected thereto such as those generally found in four-stroke engines. This is particularly true regarding vertically oriented two-stroke engines used in marine outboard engines. 
         [0005]    In particular, it is know in the art to lubricate the connecting rod bearing assemblies of vertically oriented two-stroke engines by spraying lubricant within the crankcase in the vicinity of the connecting rod bearing assemblies rotating path using low capacity lubricant pumps. U.S. Pat. No. 5,193,500 and U.S. Pat. No. 5,375,573 provide examples of such connecting rod bearing assemblies lubrication systems. 
         [0006]    However, since lubricant is not discharged directly within or close to the connecting rod bearing assemblies, a significant volume of lubricant is required to appropriately lubricate the connecting rod bearing assemblies. Furthermore, a significant portion of the lubricant sprayed into the crankcase finds its way to the combustion chamber of the cylinders, and incomplete combustion of such lubricant within the combustion chamber increases the engine&#39;s pollutant emissions. 
         [0007]    In view of the above, there is a need for a vertically oriented two-stroke engine having a lubrication system for the connecting rod bearings assemblies discharging a limited volume of lubricant in the vicinity of such connecting rod bearing assemblies so that less lubricant need to be used and less lubricant is ultimately burned in the combustion chamber, which entails that less pollutant emissions are release in the atmosphere when the two-stroke engine is used. 
       SUMMARY 
       [0008]    It is an object of the present invention to ameliorate at least some of the inconveniences present in the prior art by providing a crankshaft having a receiving platform for catching lubricant dropping from a main bearing assembly, the receiving platform having at least one wall disposed thereon, said wall having one point that is the furthest from the rotational axis of the crankshaft, and one channel defined in the platform having an inlet disposed close to the point of the wall that is furthest from the rotational axis of the crankshaft, the channel having an outlet in the vicinity of a connecting rod bearing assembly, so that lubricant dropped on the receiving platform will flow to the connecting rod bearing assembly. 
         [0009]    It is another object of the present invention to provide a crankshaft for a two-stroke engine having a crankshaft body defining a rotational axis. The crankshaft body comprises at least one main bearing journal and at least one crankpin connected thereto, the at least one crankpin being axially spaced from the at least one main bearing journal. The crankshaft body also comprises at least one receiving platform connected thereto, the at least one receiving platform being disposed between the at least one main bearing journal and the at least one crankpin. The at least one receiving platform has a top surface and a bottom surface, the top surface being disposed between the bottom surface and the main bearing journal. The top surface also has an edge and a wall, portions of the wall being non-equidistant from the rotational axis of the crankshaft body and one of the portions of the wall being furthest from the rotational axis, the one of the portions being an outermost portion. At least one channel is defined at least in part within the at least one receiving platform, the at least one channel having a channel inlet and a channel outlet. The channel inlet is disposed between the outermost portion and the rotational axis, in proximity to the outermost portion. The channel outlet is disposed in proximity to the at least one crankpin. 
         [0010]    In one aspect, the at least one main bearing journal, the at least one crankpin and the at least one receiving platform are integrally formed with the crankshaft body. 
         [0011]    In an additional aspect, the channel outlet is further from the rotational axis than the channel inlet. 
         [0012]    In a further aspect, at least a portion of the channel extends away from the rotational axis as the channel extends from the channel inlet to the channel outlet. 
         [0013]    In an additional aspect, the wall defines a closed perimeter disposed between the wall and the rotational axis. 
         [0014]    In a further aspect, the shape of the closed perimeter is one of a circle, an oval and an ellipse. 
         [0015]    In an additional aspect, the shape of the closed perimeter is a circle, a center of the circle being offset from the rotational axis. 
         [0016]    In a further aspect, the crankshaft further comprises a recess formed within the top surface of the at least one receiving platform and the inlet of the at least one channel is disposed within the recess. 
         [0017]    In an additional aspect, tithe at least one crankpin is at least two crankpins, the at least one channel is at least two channels, and the at least two channels has respective channel inlets disposed adjacent to each other. One of the two channels has a channel outlet disposed in proximity to one of the at least two crankpins, and an other of the two channels has a channel outlet disposed in proximity to an other of the at least two crankpins. 
         [0018]    In a further aspect, when the crankshaft is in use in the two-stroke engine, the rotational axis is generally vertical, the at least one main bearing journal is housed within at least one main bearing body, the at least one main bearing journal and the at least one main bearing body forming an at least one main bearing assembly, and the at least one crankpin is housed in at least one connecting rod bearing body, the at least one crankpin and at least one connecting rod bearing forming an at least one connecting rod bearing assembly. Lubricant is supplied to the main bearing assembly and at least a portion of the lubricant drops from the main bearing assembly on the top surface of the receiving platform. A portion of the lubricant on the top surface of the receiving platform is induced by centrifugal force to flow to the outermost portion and lubricant within the outermost portion flows in the channel via the channel inlet. Lubricant flowing in the channel is discharged from the channel outlet, and from the channel outlet the lubricant flows to the at least one connecting rod bearing assembly. 
         [0019]    In an additional aspect, the receiving platform is a sealing plate. 
         [0020]    It is another object of the present invention to provide a crankshaft for a two-stroke engine having a crankshaft body defining a rotational axis. The crankshaft body comprises at least one main bearing journal and at least one crankpin connected thereto, the at least one crankpin being axially spaced from the at least one main bearing journal. The crankshaft body also comprises at least one receiving platform connected thereto, the at least one receiving platform being disposed between the at least one main bearing journal and the at least one crankpin. The at least one receiving platform has a top surface and a bottom surface, the top surface being disposed between the bottom surface and the main bearing journal. The top surface has an edge and at least one wall, portions of the at least one wall being non-equidistant from the rotational axis of the crankshaft body and at least one portion of the at least one wall being more distant from the rotational axis than the other portions of the at least one wall, the at least one of the portions being at least one outer portion. At least one channel is defined at least in part within the at least one receiving platform, the at least one channel having a channel inlet and a channel outlet. The channel inlet is disposed between the at least one outer portion and the rotational axis, in proximity to the at least one outer portion. The channel outlet is disposed in proximity to the at least one crankpin. 
         [0021]    In a further aspect, the at least one main bearing journal, the at least one crankpin and the at least one receiving platform are integrally formed with the crankshaft body. 
         [0022]    In an additional aspect, the channel outlet is further from the rotational axis than the channel inlet. 
         [0023]    In a further aspect, the at least one channel extends away from the rotational axis as the at least one channel extends from the channel inlet to the channel outlet. 
         [0024]    In an additional aspect, the at least one wall is at least two walls, the at least one outer portion is at least two outer portions, and the at least one channel is at least two channels. Each one of the at least two channels has an inlet and an outlet. Each of the at least two outer portions has disposed therein at least one of the channel inlets. 
         [0025]    In a further aspect, the at least one crankpin is at least two crankpins and the channel outlet of at least one of the at least two channels is disposed in proximity to one of the at least two crankpins. The channel outlet of at least one other of the at least one channel is disposed in proximity to at least one other of the at least two crankpins. 
         [0026]    It is another object of the present invention to provide a crankshaft for a two-stroke engine having a crankshaft body defining a rotational axis. The crankshaft body comprises at least one main bearing journal and at least one crankpin connected thereto, the at least one crankpin being axially spaced from the at least one main bearing journal. The crankshaft also comprises at least one receiving platform connected thereto, the at least one receiving platform being disposed between the at least one main bearing journal and the at least one crankpin. The at least one receiving platform has a top surface and a bottom surface, the top surface being disposed between the bottom surface and the main bearing journal. The top surface has an edge and a wall defining a closed perimeter, portions of the closed perimeter being non-equidistant from the rotational axis and at least one portion of the closed perimeter being more distant from the rotational axis than the other portions of the closed perimeter, the at least one of the portions being at least one outer portion. At least one channel is defined at least in part within the at least one receiving platform, the at least one channel having a channel inlet and a channel outlet. The channel inlet is disposed within the closed perimeter in proximity to the at least one outer portion, and the channel outlet is disposed in proximity to the at least one crankpin. 
         [0027]    In an additional aspect, the at least one main bearing journal, the at least one crankpin and the at least one receiving platform are integrally formed with the crankshaft body. 
         [0028]    In a further aspect, the at least one channel is at least two channels, each one of the at least two channels having an inlet and an outlet. The at least one outer portion of the closed perimeter is at least two outer portions, and each of the at least two outer portions have disposed therein at least one of the channel inlets. 
         [0029]    In an additional aspect, the at least one crankpin is at least two crankpins. The channel outlet of at least one of the at least two channels is disposed in proximity to one of the at least two crankpins, and the channel outlet of at least one other of the at least one channel is disposed in proximity with at least one other of the at least two crankpins. 
         [0030]    It is another object of the present invention to provide a two-stroke engine comprising an engine casing, at least one cylinder disposed within the engine casing, and at least one piston movable within the at least one cylinder. The two-stroke engine also comprises a crankshaft having a crankshaft body defining a rotational axis. The crankshaft body comprises at least one main bearing journal, at least one crankpin and at least one receiving platform having a top surface and a bottom surface, the at least one main bearing journal, crankpin and receiving platform being connected to the crankshaft body. The at least one crankpin is axially spaced from the at least one main bearing journal and the at least one receiving platform is disposed so that to top surface is disposed between the bottom surface and at least one main bearing journal. The crankshaft is rotatably mounted within the engine casing via at least one main bearing assembly comprising a main bearing body and one of the at least one main bearing journal, the main bearing body being connected to the engine casing. At least one connecting rod has a first end and a second end, the first end being operatively connected to the at least one piston and the second end being rotatably connected to the crankshaft via a connecting rod bearing assembly comprising a connecting rod body and one of the at least one crankpin, the connecting rod body being connected to the second end of the connecting rod. The top surface of the at least one receiving platform has an edge and a wall, portions of the wall being non-equidistant from the rotational axis and one of the portions of the wall being furthest from the rotational axis, the one of the portions being an outermost portion. At least one channel is defined at least in part within the at least one receiving platform, the at least one channel having a channel inlet and a channel outlet. The channel inlet is disposed between the outermost portion and the rotational axis, in proximity to the outermost portion. The channel outlet is disposed in proximity to the connecting rod bearing assembly of one of the at least one connecting rod. 
         [0031]    In an additional aspect, the at least one main bearing journal, the at least one crankpin and the at least one receiving platform are integrally formed with the crankshaft body. 
         [0032]    In a further aspect, the channel extends away from the rotational axis as the channel extends from the channel inlet to the channel outlet. 
         [0033]    In an additional aspect, the wall defines a closed perimeter. 
         [0034]    For purposes of this application, terms used to locate elements on an engine or their spatial orientation, such as “forwardly”, “rearwardly”, “front”, “back”, “rear”, “left”, “right”, “up”, “down”, “above”, and “below”, are as they would normally be understood by a person operating the engine in its normal operation position. 
         [0035]    Embodiments of the present invention each have at least one of the above-mentioned aspects and/or aspects, but not necessarily have all of them. It should be understood that some aspects of the present invention that have resulted from attempting to attain the above-mentioned objects may not satisfy these objects and/or may satisfy other objects not specifically recited herein. 
         [0036]    Additional and/or alternative features, aspects and advantages of the embodiments of the present invention will become apparent from the following description, the accompanying drawings and the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0037]    For a better understanding of the present invention as well as other aspects and further features thereof, reference is made to the following description which is to be used in conjunction with the accompanying drawings, where: 
           [0038]      FIG. 1  is a transverse cross-sectional view of a portion of a two-stroke engine; 
           [0039]      FIG. 2  is a perspective view of a crankshaft according to a first embodiment; 
           [0040]      FIG. 3  is a cross-sectional view of a portion of a crankcase and a portion of the crankshaft of  FIG. 2 ; 
           [0041]      FIG. 3(   a ) is a enlarged portion of  FIG. 3 ; 
           [0042]      FIG. 4  is a perspective view of the crankshaft of  FIG. 2  with three main bearings and two connecting rods mounted thereto; 
           [0043]      FIG. 5  is a perspective view of an enlarged portion of the crankshaft of  FIG. 2 ; 
           [0044]      FIG. 6  is a transverse cross-sectional view of the crankshaft of  FIG. 2  taken along line  6 - 6  in  FIG. 2 ; 
           [0045]      FIG. 6(   a ) is a transverse cross-sectional view of a crankshaft according to another embodiment taken above a sealing plate thereof; 
           [0046]      FIG. 7(   a ) is a cross-sectional view of a portion of the crankshaft of  FIG. 2  taken along line  7 - 7  in  FIG. 6 ; 
           [0047]      FIG. 7(   b ) is a cross-sectional view of a portion of the crankshaft of  FIG. 2  taken along line  7 - 7  in  FIG. 6 ; 
           [0048]      FIG. 8(   a ) is another cross-sectional view of a portion of the crankshaft of  FIG. 2  taken along line  8 - 8  in  FIG. 6 ; 
           [0049]      FIG. 8(   b ) is another cross-sectional view of a portion of the crankshaft of  FIG. 2  taken along line  8 - 8  in  FIG. 6 ; 
           [0050]      FIG. 9  is a cross-sectional view of a portion of a crankshaft according to another embodiment taken along its rotational axis; 
           [0051]      FIG. 10  is a transverse cross-sectional view of a crankshaft according to another embodiment taken above a sealing plate thereof; 
           [0052]      FIG. 11  is a transverse cross-sectional view of a crankshaft according to another embodiment taken above a sealing plate thereof; and 
           [0053]      FIG. 12  is a transverse cross-sectional view of a crankshaft according to another embodiment taken above a sealing plate thereof. 
       
    
    
     DETAILED DESCRIPTION 
       [0054]      FIG. 1  illustrates a conventional vertically oriented two-stroke engine  10  comprising a crankcase  12  and a cylinder block  14  connected to the crankcase  12 . 
         [0055]    A cylinder  16  is disposed in the cylinder block  14  and has an exhaust port  18  and a transfer port  19 . The cylinder  16  may be formed in the cylinder block  14  in any suitable manner known in the art, such as by disposing a cylinder liner in a cylindrical bore formed in the cylinder block  14 , or by coating the inner surface of the cylindrical bore with a suitable coating such as Nicasil. 
         [0056]    The crankcase  12  has an admission port  20  and an internal chamber  24 . A crankshaft  26  is disposed in the internal chamber  24  of the crankcase  12 . 
         [0057]    A piston  28  is connected to the crankshaft  26  via a connecting rod  30  so as to reciprocate in the cylinder bore  32 . The piston  28  is adapted to open or close the exhaust port  18  and a transfer port  19 . 
         [0058]    The two-stroke engine  10  has more than one cylinder  16 , each having an exhaust port  18  and a transfer port  19 , a corresponding number of piston  28  housed therein and a corresponding number of connecting rod  30  connected to the crankshaft  26 . For each corresponding cylinder  16 , the crankcase  12  has one corresponding admission port  20  and one internal chamber  24 . In this embodiment, the two-stroke engine  10  is a V-6 and has therefore six cylinders  16  disposed in a “V” configuration. 
         [0059]    As shown in  FIG. 2 , the crankshaft  26  comprises a crankshaft body  100  defining a rotational axis  102 . The crankshaft body  100  comprises the main bearing journals  104 ( a ),  104 ( b ),  104 ( c ), three groups of two crankpins  106 ( a ),  106 ( b ) and three groups of three sealing plates  108 ( a ),  108 ( b ),  108 ( c ). Each of the main bearing journals  104 , crankpins  106  and sealing plates  108  are integrally formed with the crankshaft body  100  although it is contemplated that in other embodiments, they may consist of distinct parts connected together by any suitable mean known in the art. Each sealing plate  108  has a circumferential groove  109  defined therein for receiving a sealing ring (not shown). 
         [0060]    The crankshaft body  100  also comprises shafts  110  and  112  at each of its extremities. Shaft  110  connects the crankshaft  26  to the flywheel (not shown) of the two-stroke engine  10 , and shaft  112  connects the crankshaft  26  to the drive shaft (not shown) of the two-stroke engine  10 . Counterweights  114 ( a ),  114 ( b ) are disposed on the crankshaft body  100  to balance the crankshaft  26 . It is contemplated that in other embodiments, the crankshaft body may comprises additional bearing journals, including end main bearing journals, as well as other structures for connecting the crankshaft  26  to the two-stroke engine&#39;s  10  flywheel and drive shaft. It is also contemplated that in other embodiments, other counterweights may be disposed along the crankshaft body  100 . 
         [0061]    As shown in  FIG. 4 , the crankshaft  26  is mounted within the crankcase  12  via main bearing assemblies  200 ( a ),  200 ( b ),  200 ( c ), each of which comprises a main bearing body  202 , one of the main bearing journal  104  housed therein, and a plurality of needle bearings  203  (see  FIGS. 3 and 3(   a )). The needle bearings  203  are housed in the main bearing body  202  between the main bearing body  202  and the main bearing journal  104  for supporting the main bearing journal  104  within the main bearing body  202  and allowing the main bearing journal  104  to rotate within the main bearing body  202 . Ports  206  are defined within the main bearing body  202  of each main bearing assembly  200 , and a conduit  204  is fluidly connected to each port  206 . Lubricant flows within the main bearing assemblies  200  through conduits  204  and ports  206 . 
         [0062]    As shown in  FIG. 4 , the crankshaft  26  is connected to each of the connecting rods  30  via a connecting rod bearing assembly  250  comprising a main bearing body  252  connected to a connecting rod  30 , one of the crankpins  106  housed within the main bearing body  252 , and a plurality of needle bearings (not shown) housed in the main bearing body  252  between the main bearing body  252  and the crankpin  106  for supporting the crankpin  106  within the main bearing body  252  and allowing the crankpin  106  to rotate within the main bearing body  202 . 
         [0063]    As shown in  FIGS. 1 to 4 , the sealing plates  108  are disposed between each main bearing journal  104  and crankpins  106  for defining internal chambers  24  within the crankcase  12 . When the crankshaft  26  is standing in a vertical position in the crankcase  12  of the vertically oriented two-stroke engine  10 , the sealing plates  108 ( a ) are disposed adjacent to and below each one of the main bearing journals  104  and therefore, once the crankshaft  26  is mounted in the crankcase  12 , adjacent to and below each main bearing assemblies  250 . The sealing plates  108 ( b ) are disposed between successive crankpins  106  along the crankshaft body  100  and therefore, once the crankshaft  26  is connected to the connecting rods  30 , between two connecting rod bearing assemblies  250 . When the crankshaft  26  is standing in a vertical position, sealing plates  108 ( c ) are disposed adjacent to and above each one of the main bearing journals  104  and therefore, once the crankshaft  26  is mounted in the crankcase  12 , adjacent to and above each main bearing assemblies  250 . 
         [0064]    It is contemplated that in other embodiments where the two-stroke engine  10  does not have independent internal chambers  24 , the crankshaft body  100  would not comprise sealing plates  108  but rather other structures connecting the main bearing journals  104  and crankpins  106 . 
         [0065]    As shown in  FIG. 5  each one of the sealing plates  108 ( a ) defines a platform  300  having a top surface  302 , and a bottom surface  304 . It is contemplated that in other embodiments where the crankshaft body  100  does not comprise sealing plates  108 , the platforms  300  are defined by the other structure connecting the main bearing journals  104  and crankpins  106 . 
         [0066]    The top surface  302  has an edge  306  and a wall  308  defining a closed perimeter  310 . In this embodiment, the wall  308  is formed by a ring  312  made of steel and welded to the top surface  302 . It is contemplated that in other embodiments, the ring  312  may be made of any other hard material fastened to the top surface  302  by any other suitable mean. It is also contemplated that in other embodiments, the wall  308  can be integrally formed with the platform  300 . It is also contemplated that the wall  308  could be formed by a recess in the platform  300 . 
         [0067]    As shown in  FIG. 6 , the closed perimeter  310  defines a circle having a central point  311  that is offset from the rotational axis  102 . Point  314  is a point along the closed perimeter  310  that is further from the rotational axis  102  than any other point of the closed perimeter  310 . In this embodiment, the point  314  is also closer to the edge  306  than any other point of the closed perimeter  310 .  FIG. 6(   a ) shows another embodiment in which the circle defined by the closed perimeter  310  has been moved further toward a portion of the edge  306  to more clearly show that the central point  311  is offset from the rotational axis  102 . 
         [0068]    It is contemplated that in other embodiments, the closed perimeter  310  may have any other suitable form or shape, such as an oval, an ellipse, an hexagon, an octagon, or any regular or irregular form or shape, as long as the closed perimeter  310  has a point such as the point  314  that is further from the rotational axis  102  than any other point of the closed perimeter  310 , whether this is due to the particular shape of the closed perimeter  310  and/or to how the perimeter  308  is disposed within the top surface  302 . 
         [0069]    As shown in  FIGS. 3 ,  3 ( a ) and  7 ( a ), a channel  316  is defined within the platform  300  and the crankpin  106 ( a ) that is adjacent to and below the platform  300 . The channel  316  comprises two portions  316 ( a ) and  316 ( b ) and has an inlet  318  defined within the closed perimeter  310  of the top surface  302 , close to the point  314 . The channel  316  also has an outlet  320  defined within the exterior surface of the crankpin  106 ( a ) and facing the needle bearings (not shown) within the connecting rod bearing assembly  250 . 
         [0070]    As shown in  FIG. 8(   a ), a second channel  324  is defined within the platform  300 , the crankpin  106 ( a ), the sealing plate  108 ( b ) and the crankpin  106 ( b ) that is adjacent and below the sealing plate  108 ( b ). The channel  324  comprises two portions  324 ( a ) and  324 ( b ) and has an inlet  326  defined within the closed perimeter  310  of the top surface  302 , close to the point  314 . The channel  324  also has an outlet  328  defined within the exterior surface of the crankpin  106 ( b ) and facing the needle bearings (not shown) within the connecting rod bearing assembly  250 . 
         [0071]    As shown in  FIGS. 7(   b ) and  8 ( b ), axes  315 ,  325  passing through and parallel to portions  316 ( a ),  324 ( b ) of the channels  316 ,  324  define acute angles with axis  101 ,  103  which are parallel to the rotational axis  102  such that the lower portions  332 ,  334  of the portions  316 ( a ),  324 ( b ) of the channels  316 ,  324  are further from the rotation axis  102  than the inlets  318 ,  326 . 
         [0072]    It is contemplated that in another embodiment (not shown), the channels  316 ,  324  can be made of only one portion extending from the inlets  318 ,  326  to the outlets  320 ,  328 , and that the outlets  320 ,  328  can be disposed in other locations in proximity with crankpins  106 ( a ),  106 ( b ) or the connecting rod bearing assemblies  250 . It is also contemplated that one of channels  316 ,  324  can have other portions such as portions  316 ( a ),  316 ( b ),  324 ( a ),  324 ( b ) and that one of channels  316 ,  324  can split into two or more channels (not shown) so that one of inlets  318 ,  326  may be fluidly connected to the two outlets  320 ,  328 . 
         [0073]    In the embodiment described in  FIGS. 1 to 9 , when the crankshaft  26  is in use in the crankcase  12  of the vertically oriented two-stroke engine  10 , lubricant is supplied to each of the main bearing assemblies  200  via conduits  204  and ports  206 . A portion of the lubricant supplied to the main bearing assemblies  200  drops therefrom on the top surfaces  302  of each platforms  300  defined by the sealing plates  108 . A portion of the lubricant received by the platforms  300  falls within the closed perimeter and is induced by centrifugal force to flow toward the wall  308 . The centrifugal force then causes the portion of the lubricant to flow along the wall  308  toward the point  314  and to accumulate in the portion of the closed perimeter  310  which is close to the point  314  against the wall  308 . A portion of the lubricant accumulated in the portion of the closed perimeter  310  which is close to the point  314  flows within the channels  316 ,  324  via the inlets  318 ,  326  and is discharged from the outlets  320 ,  328  in the connecting rod bearing assemblies  250 . Since portions  316 ( a ),  324 ( a ) of the channels  316 ,  324  extend downwardly away from the rotation axis  102 , the centrifugal force assists the gravitational force for drawing lubricant into the inlets  318 ,  328  and through the channels  316 ,  324 . 
         [0074]    It is contemplated that in another embodiment shown in  FIG. 9 , a recess  317  is defined in top surface  302  of the platform  300  close to the point  314 , and the inlets  316 ,  326  are disposed within the recess  315 . When the crankshaft  26  is in use in the crankcase  12  of the vertically oriented two-stroke engine  10 , lubricant accumulates in the recess  317 . 
         [0075]    In another embodiment shown in  FIG. 10 , the closed perimeter  310  defines an ellipse and has two points  314 ( a ),  314 ( b ) that are further from the rotational axis  102  than any other point of the closed perimeter  310 . The inlet  318  is defined within the closed perimeter  310 , close to the point  314 ( a ), while the inlet  326  is defined within the closed perimeter  310 , close to the point  314 ( b ). It is contemplated that in another embodiment, (not shown) recesses such as the recess  317  can be defined in the top surface  302  of the platform  300  close to each of the points  314 ( a ),  314 ( b ) and that the inlets  318 ,  326  can be disposed within those recesses. Channels (not shown) such as channels  316 ,  324  have a suitable number of portions (not shown) such as portions  316 ( a ),  316 ( b ),  324 ( a ),  324 ( b ) suitably defined within the platform  300 , and have outlets (not shown) such as outlets  320 ,  328  disposed in the exterior surface of one of the crankpins  106 ( a ),  106 ( b ), or in proximity with the crankpins  106 ( a ),  106 ( b ) or the connecting rod bearing assemblies  250 . 
         [0076]    It is also contemplated that in other embodiments (not shown) the closed perimeter  310  may define any other shape having two or more points such as point  314  that are further from the rotational axis  102  than any other point of the closed perimeter  310  and a corresponding number of channel inlets such as inlets  318 ,  326  connected to two or more channels such as channels  316 ,  324  (which may have various suitable portions such as portions  316 ( a ),  316 ( b ),  324 ( a ),  324 ( b ) defined with the platform  300 ) having outlets such as outlets  320 ,  328  disposed in the exterior surface of the crankpins  106 ( a ),  106 ( b ), or in proximity with the crankpins  106 ( a ),  106 ( b ) or the connecting rod bearing assemblies  250 . 
         [0077]    In a further embodiment shown in  FIG. 11 , the wall  308  does not define a closed perimeter such as the closed perimeter  310  but rather an arc  336  having a center of curvature  311  that is offset from the rotational axis  102 . The point  314  is disposed along the arc  336  and is further from the rotational axis  102  than any other point of the arc  336 . It is contemplated that in other embodiments (not shown), the wall  308  may define any other shape or form permitting to have a point such as point  314  that is further from the rotational axis  102  than any other point of the shape or form defined by the wall  308 . The wall  308  may also be disposed elsewhere on the top surface  302  of the platform  300  as long as the shape defined thereby has a point such as the point  314  that is further from the rotational axis  102  than any other point of that shape. In this embodiment, the inlets  318 ,  326  are disposed close to the point  314  and the channels  316 ,  324  and channel outlets  320 ,  328  are as described with regard to the embodiment shown in  FIGS. 1 to 9 . 
         [0078]    In yet another embodiment, shown in  FIG. 12 , two walls  308 ( a ),  308 ( b ) define two curved lines  336 ( a ),  336 ( b ). The point  314 ( a ) is disposed along the line  336 ( a ) and is further from the rotational axis  102  than any other point along the line  336 ( a ), and the point  314 ( b ) is disposed along the line  336 ( b ) and is further from the rotational axis  102  than any other point along the line  336 ( b ). In this embodiment, the inlet  318  is disposed close to the point  314 ( a ) and the inlet  326  is disposed close to the point  314 ( b ). Channels (not shown) such as channels  316 ,  324  have a suitable number of portions (not shown) such as portions  316 ( a ),  316 ( b ),  324 ( a ),  324 ( b ) suitably defined within the platform  300 , and have outlets (not shown) such as outlets  320 ,  328  disposed in the exterior surface of the crankpins  106 ( a ),  106 ( b ), or in proximity with the crankpins  106 ( a ),  106 ( b ) or the connecting rod bearing assemblies  250 . 
         [0079]    It is contemplated that in other embodiments (not shown), the walls  308 ( a ),  308 ( b ) may define any other shapes, forms or lines, and each of those shapes, forms or lines may or may not be similar to each other even if the walls are disposed on a same top surface  302  of a platform  300  (as shown in  FIG. 12 ), as long as such shapes, forms or lines permit to have points such as points  314 ( a ),  314 ( b ) that are further from the rotational axis  102  than any other point along the shapes, forms or lines defined by the walls  308 ( a ),  308 ( b ). It is also contemplated that more than two walls can be disposed on a single top surface  302  of a platform  300 , each wall defining a shape or form having a point such as point  314  that is further from the rotational axis  102  than any other point of the shape or form defined by this wall. In such embodiments, inlets such as inlets  318 ,  326  are disposed close to each point such as point  314 . Channels such as channels  316 ,  324  have a suitable number of portions such as portions  316 ( a ),  316 ( b ),  324 ( a ),  324 ( b ) suitably defined within the platform  300  and have outlets such as outlets  320 ,  328  disposed in the exterior surface of the crankpins  106 ( a ),  106 ( b ), or in proximity with the crankpins  106 ( a ),  106 ( b ) or the connecting rod bearing assemblies  250 . 
         [0080]    It is also contemplated that there may be only one inlet such as inlet  318  connected to only one outlet such as outlet  320  for providing lubricant to only one connecting rod bearing assembly  250 , that inlets such as inlets  318 ,  324  may be connected to only one such outlet for providing lubricant to only one connecting rod bearing assembly  250 . It is also contemplated that one inlet such as inlet  318  may be connected to two or more outlets such as outlets  320 ,  328  for providing lubricant to two or more connecting rod bearing assemblies  250 . Finally, it is contemplated that more than two inlets such as inlets  318 ,  326  may be connected to more than two outlets such as outlets  320 ,  328  for providing lubricant to more than two connecting rod bearing assemblies  250 . 
         [0081]    Modifications and improvement to the above described embodiments may become apparent to those skilled in the art. The foregoing description is intended to be exemplary rather than limiting. Furthermore, the dimensions of features of various components that may appear on the drawings are not meant to be limiting, and the size of the components therein can vary from the size that may be portrayed in the figures herein. The scope of the present invention is therefore intended to be limited solely by the scope of the appended claims.

Technology Classification (CPC): 5