Abstract:
In a V-type internal combustion engine having a crankshaft oriented in a substantially horizontal direction, drainage channels for draining liquid such as rainwater pooling within a recess formed within the V-shaped of the engine are formed in covers for covering the end surface of the internal combustion engine in an axial direction of the crankshaft. Accordingly, liquid such as rainwater pooling on the V-shaped bank of the V-type internal combustion engine is advantageously drained from the engine with the present apparatus and methods.

Description:
BACKGROUND OF THE INVENTION  
       CROSS-REFERENCES TO RELATED APPLICATIONS  
         [0001]    This nonprovisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 2001-329938 filed in Japan on Oct. 26, 2001, the entirety of which is herein incorporated by reference.  
           [0002]    1. Field of the Invention  
           [0003]    The present invention relates to a V-type internal combustion engine capable of draining liquid, e.g., such as rainwater pooled within a space formed in a V-shaped bank of the internal combustion engine, and more particularly to a V-type internal combustion engine having a crankshaft oriented in a substantially horizontal direction.  
           [0004]    2. Description of the Background Art  
           [0005]    In a V-type internal combustion engine having a crankshaft oriented in a substantially horizontal direction, e.g., for example as seen in JP-U-62-69029, the entirety of which is hereby incorporated by reference, a coolant pump is disposed on one end surface of the internal combustion engine at a position adjacent to the V-shaped bank of cylinders. Rainwater falling from above pools within the space formed in the V-bank and is difficult to removed or drained therefrom.  
           [0006]    In the case of an internal combustion engine to be mounted on a motorcycle, when the engine is exposed to the elements and rain falls thereon, a drive unit of a dynamic valve system and a generator are disposed at the V-bank on both sides of the internal combustion engine. Accordingly, liquid such as rainwater cannot be drained and may tend to pool and eventually cause damage to the surrounding components.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention overcomes the shortcomings associated with the background art and achieves other advantages not realized by the background art.  
           [0008]    An object of the present invention is to provide a v-type internal combustion engine in which the disadvantages of the background art are overcome and/or reduced.  
           [0009]    One or more of these and other objects are accomplished by a V-block internal combustion engine comprising a crankshaft orientated in a substantially horizontal direction; a V-block cylinder block opening upwardly with respect to the horizontal direction of the crankshaft; a V-shaped valley being formed within an upper portion of the V-block cylinder block; a cover for covering an end surface of the internal combustion engine with respect to a direction of the crankshaft; a drainage channel for draining liquid pooling in the V-shaped valley; wherein the V-shaped valley is formed in the cover.  
           [0010]    One or more of these and other objects are further accomplished by an internal combustion engine comprising at least four cylinders and four pistons of the engine operatively engaged in a four cycle arrangement; a crankcase; a crankshaft orientated in a substantially horizontal direction; a V-block, cylinder block opening upwardly with respect to the horizontal direction of the crankshaft and being connected to an upper end surface of the crankcase; a V-shaped valley being formed within an upper portion of the V-block cylinder block; a cover for covering an end surface of the internal combustion engine with respect to a direction of the crankshaft; a drainage channel for draining liquid pooling in the V-shaped valley; wherein the V-shaped valley is formed in the cover; an oil pan connected on a lower end surface of the crankcase; a pair of left and right cylinder heads; a front cover being connected to a front face of the crankcase and V-block cylinder block; and a rear cover being connected to a rear face of the crankcase and the V-block, cylinder block.  
           [0011]    One or more of these and other objects are further accomplished by a method of preventing a collection of water in the V-shaped valley of either of the aforementioned internal combustion engines, the method comprising the steps of draining liquid accumulating within the V-shaped valley being formed within the upper portion of the V-block cylinder block; and guiding the liquid through the drainage channel to a position external to the internal combustion engine.  
           [0012]    Since liquid such as rainwater fallen from above to the aforementioned V-type internal combustion engine is drained out of the internal combustion engine through the V-shaped valley, the V-type internal combustion engine is prevented from rusting and/or contamination from foreign liquids and matter. Therefore, corrosion or dirt is prevented from occurring at the V-shaped bank valley of the aforementioned V-type internal combustion engine. Even when corrosion or dirt occurs in the aforementioned drainage channel, it cannot be viewed from the outside, and a desirable overall appearance is maintained.  
           [0013]    According to additional aspects of the claimed invention discussed in greater detail hereinafter, the aforementioned drainage channel is isolated from the internal space of the internal combustion engine inwardly with the front cover. Liquid pooled in the aforementioned V-shaped bank valley and drained therefrom will never mix with engine oil or the like. Since the aforementioned drain port faces sideways and obliquely downward of the internal combustion engine, drained liquid will never flow downward along the side surface of the internal combustion engine. In addition, the drainage channel does not impair the appearance because it is provided at an indistinctive position. When the crankshaft is mounted in the direction of travel of a compact vehicle such as a motorcycle, the arrangement is even more effective because the aforementioned drain port cannot be viewed from the front.  
           [0014]    When the aforementioned drainage channel does not require a specific member for forming the drainage channel, the number of the components can be reduced and thus the costs can be reduced. In addition, since the communication passage introducing liquid downward from the upper portion of the internal combustion engine is laid along the outlet passage of the water pump, the outlet passage of the water pump feeding coolant from the lower portion of the internal combustion engine toward the respective cylinder on the upper portion of the internal combustion engine does not interfere with the aforementioned communication passage.  
           [0015]    Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    The present invention will become more fully understood from the detailed description given hereinafter and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:  
         [0017]    [0017]FIG. 1 is a front view of a V-type, four cylinder, four cycle internal combustion engine according to an embodiment of the present invention;  
         [0018]    [0018]FIG. 2 is a vertical, cross sectional view taken along the line II-II in FIG. 1;  
         [0019]    [0019]FIG. 3 is a frontal, cross sectional view taken along the line III-III in FIG. 2;  
         [0020]    [0020]FIG. 4 is a plan, cross sectional view taken along the line IV-IV in FIG. 1;  
         [0021]    [0021]FIG. 5 is a front view of a front cover according to an embodiment of the present invention; and  
         [0022]    [0022]FIG. 6 is a rear view of a coolant pump cover according to an embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]    The present invention will hereinafter be described with reference to the accompanying drawings. FIG. 1 is a front view of a V-type, four cylinder, four cycle internal combustion engine according to an embodiment of the present invention. FIG. 2 is a vertical, cross sectional view taken along the line II-II in FIG. 1. FIG. 3 is a frontal, cross sectional view taken along the line III-III in FIG. 2. FIG. 4 is a plan, cross sectional view taken along the line IV-IV in FIG. 1. FIG. 5 is a front view of a front cover according to an embodiment of the present invention. FIG. 6 is a rear view of a coolant pump cover according to an embodiment of the present invention. In the following discussion of the accompanying drawings, the terms “on, up and down, left and right, and front and rear” refer to directions of orientation with respect to and as viewed on the basis of the motorcycle to which an engine  1  is mounted in a preferred embodiment.  
         [0024]    A V-type, four cylinder, four stroke (cycle) internal combustion engine  1  is mounted on a motorcycle in a preferred application of the present invention. The engine  1  includes a crankshaft  11  oriented in a fore-and-aft direction of the vehicle, e.g., a so-called vertical orientation. As shown in FIG. 2, a constant-mesh gear transmission  2  is built in a rear half of an interior of the V-type four cylinder, four stroke (cycle) internal combustion engine  1 .  
         [0025]    As shown in FIG. 1 and FIG. 2, the main body of the aforementioned V-type, four cylinder, four cycle internal combustion engine  1  includes a crankcase  4 , an oil pan  3  connected on the lower end surface of the crankcase  4 , a cylinder block  5  connected to the upper end surface of the crankcase  4  and including a pair of left and right cylinder banks arranged in V-shape and constructed of four cylinders (not shown). The cylinders are arranged alternately on the left and the right with respect to the direction of the axis of rotation of the aforementioned crankshaft  11 . The engine  1  also includes a pair of left and right cylinder heads  6  connected respectively to the left and right cylinder banks, a pair of left and right head covers  7  connected to both of the cylinder heads  6 , a front cover  8  connected to the front face of the aforementioned crankcase  4  and the cylinder block  5 , and a rear cover  9  connected to the rear face of the crankcase  4  and the cylinder block  5 . The front cover  8  corresponds to a first cover as discussed in the remainder of this description.  
         [0026]    As shown in FIG. 2, a front bearing holding portion  12 , an intermediate bearing holding portion  13 , and a rear bearing holding portion  14  are formed by the combination of the crankcase  4  and the cylinder block  5  integrally therewith. The crankshaft  11  is rotatably supported by the bearings held by the front bearing holding portion  12 , the intermediate bearing holding portion  13 , and the rear bearing holding portion  14  respectively. Pistons (not shown) are slidably fitted to the aforementioned cylinders and the pistons are reciprocated by intermittent combustion of an air-fuel mixture supplied into the combustion chambers of the cylinders. The reciprocating motion of the pistons rotates the crankshaft  11  counterclockwise (clockwise when viewing the V-type, four cylinder, four stroke internal combustion engine  1  from the front) via a connecting rod  15 .  
         [0027]    The main shaft  16  is rotatably supported by the crankcase  4  at a position lower than the crankshaft  11 . An output portion of the multi plate friction speed change clutch  17  is fitted on the front end portion of the main shaft  16  projected forward from the crankcase  4 , a driven gear  19  is fitted on the input portion of the multi plate friction speed change clutch  17 , and a drive gear  18  is formed integrally with the crankshaft  11  and engages the driven gear  19 . Accordingly, a rotational torque of the crankshaft  11  is transmitted to the main shaft  16  via the multi plate friction speed change clutch  17  when the multi-plate friction speed change clutch  17  is connected.  
         [0028]    A counter shaft  20  is rotatably supported by the crankcase  4  on the right side of the main shaft  16 , a speed change gear group  21  on the main shaft side and the speed change gear group on the counter side (not shown) are provided on the main shaft  16  and the counter shaft  20  respectively. An output gear  22  on the counter shaft  20  engages the input gear  24  on the output shaft  23 , so that one of the gears in the speed change gear group  21  on the main shaft side and one of the gears in the speed change gear group on the counter side are selectively engaged by the axial movement of any one of three shift forks (not shown) provided on the shift drive shaft (not shown) Power is transmitted from the main shaft  16  via the counter shaft  20  to the output shaft  23  at a prescribed change gear ratio. A drive shaft (not shown) oriented in the fore-and-aft direction is connected to the output shaft  23 , and the drive shaft is connected to the rear axle of the motorcycle (not shown) via a pair of bevel gears (not shown). The rear wheel is driven by the rotation of the output shaft  23  and thus the motorcycle can travel.  
         [0029]    Further, an AC generator drive gear  25  is integrally fitted on the rear end portion of the crankshaft  11  projected rearward from the crankcase  4  and the cylinder block  5 . The AC generator drive gear  25  is connected to the input shaft of the AC generator  26  via a transmission mechanism (not shown), so that the crankshaft  11  and the AC generator  26  rotate simultaneously. The AC generator  26  is disposed at a valley, space or recess formed on the rear portion of the V-bank of the V-type, four cylinder, four stroke (cycle) internal combustion engine  1 .  
         [0030]    A drive sprocket  27  of the dynamic valve system (not shown) is disposed at the front portion of the crankshaft  11  projected forwardly from the front bearing holding portion  12  and at a position rearward of the drive gear  18 . As shown in FIG. 1, a cam shaft  10  is rotatably supported at a mating surface between the cylinder head  6  and the head cover  7 . An endless chain is routed between the driven sprocket that is built in the cam shaft  10  and the drive sprocket  27 , so that the cam shaft  10  is rotated at half the rotational speed of the crank shaft  11  in accordance with the rotation of the crankshaft  11 .  
         [0031]    In addition, as shown in FIG. 2 and FIG. 3, the cylinder block  5  is formed with a cam chain chamber  28  in which the aforementioned endless chain can be forwarded. As shown in FIG. 3, the bottom wall  29  of the V-bank is formed in such a manner that the portion near the widthwise center of the cylinder block  5  is the lowest. As shown in FIG. 2, the front part of the bottom wall  29  of the V-bank is slightly inclined downward (when the mating surface between the crankcase  4  and the cylinder block  5  is oriented horizontally) in comparison with the rear portion of the bottom wall  29  of the V-bank and with respect to a direction of the crankshaft  11 . Therefore, rainwater falling on the V-bank of the cylinder block  5  flows forward from the rear portion of the bottom wall  29  of the V-bank.  
         [0032]    As shown in FIG. 2, a wall  31  of the cam chain chamber extending vertically downward and forming the front wall of the cam chain chamber  28  is formed integrally with the rear end of the contact portion  30  that comes into contact with the upper portion of the front cover  8 . The lower portion of the wall  31  of the cam chain chamber is formed with a communication hole  32  in contact with the upper surface of the bottom wall  29  of the V-bank, and a vertically elongated cylindrical portion  33  in front view in contact with the upper portion of the communication hole  32  is formed so as to project forwardly from the wall  31  of the cam chain chamber.  
         [0033]    As shown in FIG. 5, the front cover  8  is formed of a set back recess  34 . The set back recess  34  is recessed rearward, on the upper left portion thereof from the border line extending obliquely from the position below the cylindrical portion  38  (which will be described hereinafter) toward the obliquely upper right when viewed from the front (obliquely upper left when viewed on the basis of the vehicle body). The set back recess  34  then extends vertically downward from a position slightly offset leftward and downward from the position below the aforementioned cylindrical portion  33 . The recess  34  then inclines toward the obliquely lower left from a position immediately above the multi plate friction speed change clutch  17 . A pump hole  35  is formed on the set back recess  34  at a lower position on the front face thereof, and coolant outlet ports  36  are formed on the set back recess  34  at the upper left and right positions thereof. Further, a shallow groove  37  is formed on the front face of the set back recess  34  so as to extend from the pump hole  35  toward the coolant outlet ports  36 .  
         [0034]    A cylindrical portion  38  having the same cross section as the vertically elongated cylindrical portion  33  projecting forward from the wall  31  of the cam chain chamber of the cylinder block  5  is provided on the upper inner surface (rear surface) of the front cover  8  so as to project toward the rear. A lead-in path  39  is defined by the cylindrical portions  33 ,  38 , and a communication hole  40  communicating with the bottom of the cylindrical portion  38  and the outer portion of the front cover  8  is provided on the front cover  8 .  
         [0035]    A coolant pump cover  41 , which corresponds to the second cover referred to hereinafter in the remainder of this description, for covering the set back recess  34  on the front cover  8  so as to be flush with the front surface of the front cover  8  is provided as shown in FIG. 6. The coolant pump cover  41  is formed with a spiral recess  43  and the coolant passage  44  of the coolant pump  42  at the position corresponding to the groove  37  of the front cover  8 . The casing of the coolant pump  42  is formed by bolts to be passed through the bolt holes  45  on the coolant pump cover  41  and screwed into the bolt holes  46  on the front cover  8 . A pump rotor (not shown) is inserted into and rotatably supported by the spiral recess  43  on the aforementioned coolant pump cover  41  from the front toward the rear, and the pump rotor is connected to the crankshaft  11  via a transmission mechanism such as a belt or the like, not shown.  
         [0036]    As shown in FIG. 4, the coolant pump cover  41  is formed with a thermostat chamber  47  at the position forward of the spiral recess  43 . The thermostat chamber  47  is connected with the inlet pipe joint  48  and a bypass pipe joint  49 . The thermostat chamber  47  accommodates a thermostat (not shown) and the inlet pipe joint  48  is connected to the radiator (not shown) via a hose (not shown). The bypass pipe joint  49  is connected to the coolant exit (not shown) of the V-type, four cylinder, four stroke (cycle) internal combustion engine  1  via a hose (not shown). The aforementioned coolant outlet port  36  is connected to the coolant passage  50  (See FIG. 3) of the V-type, four cylinder, four stroke (cycle) internal combustion engine  1 .  
         [0037]    As shown in FIG. 4, the coolant pump cover  41  is formed in such a manner that the side edge  53  of the front plate portion  52  of the coolant pump cover  41  can be brought into intimate contact with the side wall  51  of the set back recess  34  of the front cover  8 . A communication passage  56  is defined by the wall  54  and the side wall  51  of the set back recess of the front cover  8  and the front plate portion  52  and the side wall  55  of the coolant pump cover  41 .  
         [0038]    Since the embodiment shown in the figure is constructed as described above, the following operation is performed. When the V-type internal combustion engine  1  starts and the crankshaft  11  rotates, the pump rotor of the coolant pump  42  is rotated. Since the coolant is cold during startup, the thermostat (not shown) closes the water passage leading to the inlet pipe joint  48  and opens the water passage leading to the bypass pipe joint  49 .  
         [0039]    Therefore, coolant is drawn from the coolant passage  50  into the V-type internal combustion engine  1  via the hose and the bypass pipe joint  49  into the coolant passage  44  of the coolant pump  42 . After being pressurized, coolant flows through the coolant passage  44  and the coolant outlet port  36  into the coolant passage  50 . Accordingly, localized overheating is avoided in the V-type 4 cylinder 4 stroke cycle internal combustion engine  1  by the circulation of coolant. When coolant is heated to a value exceeding a prescribed temperature, a thermostat (not shown) is actuated, and the water passage led to the bypass pipe joint  49  is closed, and the water passage led to the inlet pipe joint  48  is opened.  
         [0040]    Therefore, coolant heated in the engine  1  is fed to the radiator (not shown) and cooled therein. Coolant is then cooled and drawn into the spiral recess  43  of the coolant pump  42  via the hose (not shown) and the inlet pipe joint  48  and pressurized therein. Coolant then flows back to the coolant passage  50  in the engine  1  via the coolant passage  44  and the coolant outlet port  36 , so that the engine  1  can be kept at proper temperatures.  
         [0041]    When the motorcycle (not shown) travels in rain or other foul weather, and rainwater falls on the V-type, four cylinder internal combustion engine  1 , rainwater pools on the bottom wall  29  of the V-bank of the engine  1 . The rainwater flows forward along the bottom wall  29  of the V-bank inclined downward toward the front, and passes through the communication hole  32  on the wall  31  of the cam chain chamber. The water then flows into the lead-in path  39  defined by the cylindrical portion  33  and the cylindrical portion  38 .  
         [0042]    The lower edge  53  of the front plate portion  52  of the coolant pump cover  41  is in contact with the side wall  51  of the set back recess  34  of the front cover  8  in a watertight manner (a packing or the like may be interposed as necessary). The communication passage  56  is defined by the side wall  51  of the set back recess  34  and the wall  54  of the set back recess on the front cover  8  and the front plate portion  52  and the side wall  55  of the coolant pump cover  41 . The communication passage  56  is inclined toward the lower left in front view (lower right when viewed on the basis of the vehicle body) along the side wall  51  of the set back recess  34  of the front cover  8 . Accordingly, rainwater introduced into the lead-in path  39  flows through the communication hole  40  into the communication passage  55  and then flows obliquely downward in the communication passage  55 . Water is then drained from the opening  57  between the lower end portion of the side wall  51  of the set back recess  34  on the front cover  8  and the peripheral wall  54  of the coolant pump  42  toward the outside of the vehicle.  
         [0043]    Generally, when the motorcycle is traveling, rainwater drained from the opening  57  flows rearward of the vehicle body, e.g., as a mist due to wind blown while the vehicle is moving. Therefore, the water rarely adheres on the crankcase  4 , the cylinder block  5 , the cylinder head  6  and the body of the V-type engine  1 . Accordingly, contamination of the crankcase  4 , cylinder block  5 , the cylinder head  6 , and the like due to rain may be avoided. Since the bottom wall  29  of the V-bank inclines downward toward the front, rainwater falling on the bottom wall  29  of the V-bank does not pool on the bottom wall  29  of the V-bank, but is instead drained to the outside of the engine, even when the vehicle is stopped. In addition, since the communication passage  56  is formed along the coolant passage  44  of the coolant pump  42 , the coolant passage  44  does not interfere with the communication passage  56 .  
         [0044]    The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.