Abstract:
A cylinder block structure includes a plurality of mounting bolts extending through a plurality of bearing caps and through a crank case to fix a crank shaft in a cylinder block. During operation, the crank shaft transmits detrimental horizontal stress to the bearing caps, the mounting bolts, and the crank case. A bulge portion, a plurality of reinforcing ribs, boss portions, and reinforcing oil transport structures extend away from the cylinder block to resist the horizontal stresses and prevent deformation of the mounting bolts and the bearing caps. An engine mount bracket secures the cylinder block structure to an external position and provides additional rigidity. The bulge portion, reinforcing ribs, boss portions and other structures minimize vibration and allow close tolerances by providing rigidity to the cylinder block structure without increasing wall thickness.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a cylinder block structure in a V-type engine. More particularly, the present invention relates to a cylinder block structure in which bearing caps are integrated with a crank case to reinforce selected bearing portions.  
           [0003]    2. Description of the Related Art  
           [0004]    Conventional internal combustion vehicle engines include in-line cylinder engines, opposed-cylinder engines, and V-type engines. V-type engines have cylinder banks disposed in a relative V-shape.  
           [0005]    Alternative configurations exist for V-type engines. In one configuration, an upper surface of a crank case mounts on a lower surface of a V-shaped cylinder block. In this configuration, an oil pan mounts on the lower surface of the crank case, and the V-shaped cylinder block supports a crank shaft in cooperation with bearing caps integrated with the crank case. In this configuration, a first and a second cylinder head are positioned on the upper surfaces of a first and a second cylinder bank.  
           [0006]    Referring now to FIG. 8, a V-type engine  102  includes a first through an eighth cylinder (#&#39;s 1 to #8 not shown) disposed in a V-shaped cylinder block  104  (alternatively referred to as cylinder block  104 ).  
           [0007]    Cylinder banks  106 A and  106 B are symmetrical on one-side and an opposite-side of an engine center line EC in V-shaped cylinder block  104 . Cylinder banks  106 A are centered on a one-side cylinder center line CA. Cylinder banks  106 B are centered on an opposite-side cylinder center line CB.  
           [0008]    Cylinder heads  108 A and  108 B are symmetrical on one-side and an opposite-side of engine center line EC. A bearing construction member  110  is below cylinder heads  108 A,  108 B.  
           [0009]    A crank case  112  supports V-shaped cylinder block  104 . A set of bearing caps  114  (referred to as bearing caps  114 ) are on crank case  112 . A crank shaft  116  (shown later) drives the first through eights cylinders, as will be explained. Bearing construction member  110  includes crank case  112  integrated with bearing caps  114 .  
           [0010]    An oil pan  118  is located below V-shaped cylinder block  104  and bearing construction member  110 , to aid oil circulation during engine operation.  
           [0011]    Conventionally, cylinder block  104  and crank case  112  are formed from aluminum. Bearing caps  114  are usually iron.  
           [0012]    One-side cylinder bank  106 A includes one-side cylinders  120 A, specifically, the first, third, fifth, and seventh cylinders (that is, the cylinders identified with odd numbers) in one-side cylinder bank  106 A. One-side cylinders  120 A extend in a lengthwise direction along one-side cylinder bank  106 A.  
           [0013]    Opposite-side cylinder bank  106 B includes opposite-side cylinders  120 B, specifically, the second, fourth, sixth, and eighth cylinders (having even numbers) in opposite-side cylinder bank  106 B. Opposite-side cylinders  120 B extend in a lengthwise direction along opposite-side cylinder bank  106 A.  
           [0014]    One-side cylinder center line CA passes through the center of one-side cylinders  120 A. Opposite-side cylinder center line CB passes through the center of opposite-side cylinders  120 B.  
           [0015]    One-side cylinder center line CA is set at a one-side angle θ1 from engine center line EC. Opposite-side cylinder center line CB is set at an opposite-side angle θ2 from engine center line EC. Engine center line EC passes through a center O of crank shaft  116 . An including angle α (for example 60°) exists between engine center line EC and respective one-side and opposite-side center lines CA, CB. Including angle α is equally divided between a one-side angle θ1 and an opposite-side angle θ2 on respective sides of engine center line EC.  
           [0016]    During assembly ofV-type engine  102 , an upper surface of crank case  112  mounts to a lower surface of V-shaped cylinder block  104 . Oil pan  118  is then mounted on a lower surface of crank case  112  by an attachment fitting (not shown). V-shaped cylinder block  104 , in cooperation with bearing caps  114 , rotatably supports crank shaft  116  in a forward and a rearward direction along V-type engine  102 .  
           [0017]    During further assembly, respective one-side and opposite-side cylinder heads  108 A,  108 B are placed on the upper surfaces of each respective one-side and opposite-side cylinder banks  106 A,  106 B.  
           [0018]    In bearing construction member  110 , a plurality of lower mounting bolts  122 , extending through bearing caps  114 , mount crank case  112  on the lower surface of V-shaped cylinder block  104 . Lower mounting bolts  122  integrally hold bearing caps  114  and crank case  112  to V-shaped cylinder block  104 . A side mounting bolt  124  integrally holds each respective bearing cap  114  from the side of bearing construction member  110 .  
           [0019]    A main oil path  56  is in the side wall of V-shaped cylinder block  104  in a lengthwise direction. During operation, oil circulates through main oil path  56  to cool and lubricate V-type engine  102 .  
           [0020]    Referring now to FIG. 9, a first to a fifth crank journal, sequentially  126 - 1 , - 2 , - 3 , - 4 , and - 5  are formed on crank shaft  116  and spaced a predetermined distance from each other. A first to an eighth crank pin, sequentially  128 - 1 , . . . - 8 , are also formed on crank shaft  116 , in positions corresponding to respective cylinders, as will be explained.  
           [0021]    Since V-type engine  102  is an eight-cylinder engine, first through eighth crank pins  128 - 1  to - 8  are numbered #1 to #8 respectively for each respective cylinder.  
           [0022]    A pair of first crank weights  130 - 1 A,  130 - 1 B are on either side of first crank pin  128 - 1 . A second crank weight  130 - 2  is between third crank pin  128 - 3  and fourth crank pin  128 - 4 . A third crank weight  130 - 3  is between fifth crank pin  128 - 5  and sixth crank pin  128 - 6 . A pair of fourth crank weights  130 - 4 A,  130 - 4 B are on either side of eighth crank pin  128 - 8 .  
           [0023]    A first and a second crank arm  132 - 1 ,  132 - 2 , are on either side of second crank journal  126 - 2 . A third and a fourth crank arm  132 - 3 ,  132 - 4 , are on either side of third crank journal  126 - 3 . A fifth and a sixth crank arm  132 - 5  and  132 - 6  are on either side of fourth crank journal  126 - 4 .  
           [0024]    A pulley mounting projection  134  is on an end of crank shaft  116  adjacent first crank journal  126 - 1 . A starter motor gear  136  on the other end of crank shaft  116  adjacent fifth crank journal  126 - 5 .  
           [0025]    A plurality of semicircular block side shaft holes  138  extend through the lower surface of cylinder block  104 . Shaft holes  138  correspond to respective crank journal  126 - 1  to - 5  (shown later) on crank shaft  116 . In contrast to shaft holes  138 , bearing caps  114  each have case side bearing portions  142 . Bearing portions  142  each have respective semicircular case side shaft holes  140  corresponding to respective crank journals  126  on crank shaft  116 . In operation, crank shaft  116  rotates clockwise in rotation direction R.  
           [0026]    Referring now to FIGS.  10  to  14 , crank weights  130 - 1  to  130 - 4  extend away from the moving center of crank shaft  16  (as shown), and aid in force-balancing V-type engine  102  during operation.  
           [0027]    Referring now to FIGS. 15 and 16, bearing metals  144  rotatably support crank shaft  116  between respective block side shaft holes  138  (of cylinder block  104 ) and case side shaft holes  140  (of bearing caps  114 ).  
           [0028]    A plurality of one-side connecting rods  146 A (numbered - 1  through - 8 ) and opposite-side connecting rods  146 B (numbered - 1  through - 8 ) join to crank shaft  116  and operate in respective one- and opposite-side cylinder banks  106 A,  106 B, as will be explained. For convenience, member specific to the fourth cylinder in V-type engine  102  are shown. (i.e.  146 B- 4 ,  120 B- 4 , CB- 4  etc.) Each one-side and each opposite-side connecting rod  146 A- 1  to - 8  and  146 B- 1  to - 8  has a large end and a small end.  
           [0029]    In each one-side cylinder  120 A, a set of one-side connecting bolts  150 A joins the large end of each respective one-side connecting rod  146 A to respective crank pins  128  with a one-side cap  148 A.  
           [0030]    In each opposite-side cylinder  120 B, a set of opposite-side connecting bolts (not shown) joins the large end of each respective opposite side connecting rod  146 B to respective crank pins  128  with an opposite-side cap (not shown).  
           [0031]    A one-side piston  152 A is in each respective one-side cylinder  120 A. One-side piston pins  154 A connect each respective one-side piston  152 A to the small ends of each respective one-side connecting rod  146 A.  
           [0032]    An opposite-side piston  152 B is in each respective opposite-side cylinder  120 B. (i.e. opposite-side piston  152 B- 4  is in opposite-side cylinder  120 B- 4 ) Respective opposite side piston pins  154 B connect each opposite-side piston  152 B to the small ends of each respective opposite-side connecting rod  146 B.  
           [0033]    The eight-cylinders in V-type engine  102  are numbered first cylinder (#1) through eighth cylinder (#8). During operation of V-type engine  102 , the respective cylinders are ignited in sequences as shown, namely, the ignition sequence is #1, #8, #4, #3, #6, #5, #7, and #2.  
           [0034]    When V-type engine  102  operates, loads from respective one-side pistons  152 A (with one-side connecting rods  146 A), and the respective opposite-side pistons  152 B, (with opposite-side connecting rods  146 B), are applied to crank shaft  116  and received by bearing caps  114  during each cylinder ignition.  
           [0035]    When explosion arises in the engine  102 , the loads of the respective cylinders (#1 to #8 (not shown)) are applied respectively along the direction of one-side cylinder center line CA and in the direction of opposite-side cylinder center line CB.  
           [0036]    These loads each affect V-type engine  102  differently since each is affected by the sequence of ignition and by the inertial forces of the first to fourth crank weights  130 - 1  to  130 - 4  of respective adjacent cylinders. These loads also differ for engines having 4 or 6 cylinders.  
           [0037]    Referring now to FIG. 17, when the fourth cylinder (#4) is ignited in sequence (shown as  4 S in FIG. 16), a load having a horizontal portion P 4 , is applied horizontally to respective bearing cap  114 . When the third cylinder (#3) is ignited in sequence (shown as  3 S in FIG. 16), a load having a horizontal portion P 3 , is applied horizontally to respective bearing cap  114 .  
           [0038]    Thus, when fourth opposite-side piston  152 B- 4  (of fourth cylinder (#4) in opposite-side pistons  152 B) receives an explosive load along the direction of the fourth opposite-side cylinder center line CB- 4 , this explosive load is also applied to bearing cap  114 . During receipt of this explosive load, an inertial force of third crank weight  130 - 3  (counter weight) of crank shaft  116  is at least twice as large as the inertial force of second crank weight  130 - 2  (counter weight) of crank shaft  116 . Thus, as can be shown from force analysis, during ignition of fourth cylinder (#4), a resultant force FK is applied substantially horizontally to bearing cap  114 . Resultant force FK is obtained by adding a resultant force F 1 , of a load W, and an inertial force K 1 , to an inertial force K 2 . Loads Q 1 , Q 2  from crank shaft  116  are also applied horizontally to bearing caps  114 .  
           [0039]    A similar phenomenon arises during ignition/explosion in the sixth cylinder (#6). The resultant force (now shown) from the explosion load and the inertial force of fourth counter weight  130 - 4  is applied horizontally to bearing cap  114  by the affect of the above inertial force.  
           [0040]    In the conventional cylinder block structure described above, frequent problem arise since the lower mounting bolts  122  are deformed by the horizontally applied loads from crank shaft  116 , and the case side crank shaft holes (not shown) are similarly deformed. As a result of such deformation, clearances between the case side crank shaft holes and crank shaft  116  are detrimentally increased and result in damaging engine vibration and noise.  
           [0041]    In one attempt to remedy this concern, as disclosed in the cylinder block of Japanese Patent No. 3109118, attachment brackets are positioned across a series of joint portions between a cylinder block and corresponding bearing caps and are secured to a side of the cylinder block and to the sides of the bearing caps.  
           [0042]    Alternatively, to overcome the above disadvantage, countermeasures may include increasing the case side wall thickness of an aluminum crank case, adding a reinforcing member, or changing the material of the crank case (to use iron). Unfortunately, each of these countermeasures is accompanied by a disadvantageous weight and cost increase.  
         OBJECTS AND SUMMARY OF THE INVENTION  
         [0043]    It is an object of the present invention to provide a cylinder block structure which overcomes the disadvantages described above.  
           [0044]    It is another object of the present invention to provide a cylinder block structure with increased rigidity and a lower risk of failure.  
           [0045]    It is another object of the present invention to increase the rigidity of a crank case to resist horizontal forces from a crank shaft and minimize load deformation while maintaining selected bearing gaps.  
           [0046]    The present invention relates to a cylinder block structure including a plurality of mounting bolts extending through a plurality of bearing caps and a crank case to fix a crank shaft in a cylinder block. During operation, the crank shaft transmits detrimental horizontal stress to the bearing caps, the mounting bolts, and the crank case. A bulge portion, a plurality of reinforcing ribs, boss portions, and reinforcing oil transport structures extend away from the cylinder block and resist the horizontal stresses and prevent deformation of the mounting bolts and the bearing caps. An engine mount bracket secures the cylinder block structure to an external position and provides additional rigidity. The bulge portion, reinforcing ribs, boss portions and other structures minimize vibration and allow close tolerances by providing rigidity to the cylinder block structure without increasing wall thickness.  
           [0047]    According to an embodiment of the present invention there is provided a cylinder block structure, comprising: a crank case, the crank case on a first lower surface of a V-type cylinder block, a first set of bearing caps mounted on the crank case, the cylinder block and the first set of bearing caps operably supporting a crank shaft along a center axis of the cylinder block structure, the crank shaft transmitting a distorting force to at least the first set and a one-side wall of the crank case during an engine operation, means for preventing a distortion of the at least first set and the one-side wall during the engine operation, at least a bulge portion in the means for preventing, and the bulge portion extending away from at least the one-side wall and reinforcing the first set and the one-side wall, whereby the means for preventing resists the distorting horizontal force and prevents the distortion.  
           [0048]    According to another embodiment of the present invention there is provided a cylinder block structure, further comprising: a oil pump in the means for preventing, the oil pump mounted on a second lower surface of the bulge portion opposite the crank shaft, a first oil path in the means for preventing, a first oil path on a bulge side surface of the bulge portion opposite the crank shaft, the first oil path in fluid communication with a discharge path of the oil pump, a second oil path in the means for preventing, a second oil path on the a block side wall of the cylinder block opposite the crank shaft, and the second oil path providing fluid communication between the first oil path and a main oil path in the cylinder block, whereby the oil pump and the first and the second oil paths resists the distortion.  
           [0049]    According to another embodiment of the present invention there is provided a cylinder block structure, further comprising: a plurality of first boss portions in the means for preventing, the first boss portions on the one-side wall and an opposite-side wall of the crank case extending away from the crank case at spaced intervals perpendicular to the crank shaft, a plurality of second boss portions in the means for preventing, the second boss portions on at least at a one-side cylinder block wall of the cylinder block extending away from the cylinder block at spaced intervals perpendicular to the crank shaft and relative to corresponding the first boss portions, an engine mounting bracket in the means for preventing, and the engine mounting bracket rigidly joining at least one of the second boss portions and at least one of the first boss portions on the one-side wall to an external support, whereby the engine mounting bracket prevents distortion of the crank case and the cylinder block relative to the external support.  
           [0050]    According to another embodiment of the present invention there is provided a cylinder block structure, further comprising: a plurality of reinforcing ribs in the means for preventing, and the plurality of reinforcing ribs on the plurality of first boss portions on the one-side wall, whereby the reinforcing ribs stiffen the plurality of first boss portions and prevent distortion of the crank case.  
           [0051]    According to another embodiment of the present invention there is provided a cylinder block structure, comprising: a crank case, an upper surface of the crank case on a lower surface of a V-shaped cylinder block, a bearing construction member includes the crank case and a plurality of bearing caps, an oil pan on a lower surface of the crank case, the plurality of bearing caps and the crank case rotatably supporting a crank shaft along a rotation axis in the bearing construction member, a bulge portion on at least a first case side wall of the crank case extending away from the crank case, the bulge portion having a shape and being at a position countering a distorting horizontal force from the crank shaft transmitted to the bearing caps and the crank case during an engine operation, an oil pump on a lower surface of the bulge portion, a first oil path on a bulge side surface of the bulge portion in fluid communication with a discharge path of the oil pump, and a second oil path on a block side wall of the cylinder block in fluid communication between the first oil path and a main oil path of the cylinder block, whereby the oil pump, the first oil path, and the second oil path support the bulge portion and resist the distorting horizontal load.  
           [0052]    According to another embodiment of the present invention there is provided a cylinder block structure, further comprising: a plurality of first boss portions on the first and a second case side wall of the crank case, the plurality of first boss portions extending away from crank case at spaced intervals perpendicular to the crank shaft, a plurality of second boss portions on at least a first cylinder side wall of the cylinder block, the plurality of second boss portions extending away from the cylinder block at spaced intervals perpendicular to the crank shaft and relative to respective the first boss portions, at least one engine mounting bracket having at least an upper and a lower portion and fixed to an external support, the upper portion fixed to at least one of the second boss portions on the cylinder block on the first cylinder side wall, the lower portion fixed to at least one of the first boss portions on the crank case on the first case side wall, and the engine mounting bracket extending away from the cylinder block and the crank case to the external support, thereby preventing the distorting horizontal load from shifting the crank case, the cylinder block, and the set of bearing caps relative to the external support during the engine operation.  
           [0053]    According to another embodiment of the present invention there is provided a cylinder block structure, further comprising: a plurality of reinforcing ribs on the plurality of first boss portions along the first case side wall, and the reinforcing ribs stiffening the plurality of first boss portions along the first case side.  
           [0054]    According to another embodiment of the present invention there is provided a cylinder block structure, comprising: a crank case, an upper surface of the crank case on a first lower surface of a V-shaped cylinder block, a bearing construction member includes the crank case and a plurality of bearing caps, the plurality of bearing caps and the crank case rotatably supporting a crank shaft along a rotation axis of the crank case, at least a pump-mounting inclined surface on a second lower surface of the crank case, an oil pump mounted on the pump-mounting inclined surface, the pump-mounting inclined surface having a shape and a thickness countering a distorting horizontal force from the crank shaft transmitted to the bearing caps and the crank case during an engine operation, and the thickness of the pump-mounting inclined surface also increasing a rigidity of at least one case side wall of the crank case.  
           [0055]    According to another embodiment of the present invention there is provided a cylinder block structure, comprising: a crank case; at least a first set of bearing caps mounted on said crank case; means for preventing distortion of bearing caps and said crank case during an engine operation transmitting a distorting horizontal force to said bearing caps and said crank case; a bulge portion in said means for preventing; and said bulge portion extending away from a first side wall of said crank case to reinforce at least one of said crank case and said bearing caps and resist said distorting horizontal force, whereby distortion of said cylinder block structure is prevented.  
           [0056]    The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0057]    [0057]FIG. 1 is a sectional view of a V-type engine taken along the line I-I of FIG. 2 in a first embodiment of the present invention.  
         [0058]    [0058]FIG. 2 is a side elevation of the V-type engine.  
         [0059]    [0059]FIG. 3 is a bottom plan view of the crank case integrated with bearing caps supporting a crank shaft.  
         [0060]    [0060]FIG. 4 is a plan view of a crank case integrated with bearing caps.  
         [0061]    [0061]FIG. 5 is a view explaining the directions of loads applied from the crank shaft.  
         [0062]    [0062]FIG. 6 is a view showing the directions in which lower mounting bolts are attached in a second embodiment of the present invention.  
         [0063]    [0063]FIG. 7 is a front elevational view in part showing an oil pump mounted obliquely in a third embodiment.  
         [0064]    [0064]FIG. 8 is a sectional view schematically showing a conventional V-type engine without connecting rods and pistons.  
         [0065]    [0065]FIG. 9 is a side elevational view of a conventional crank shaft.  
         [0066]    [0066]FIG. 10 is a front elevational view of the crank shaft shown in FIG. 9 when it is viewed from an end thereof.  
         [0067]    [0067]FIG. 11 is a side elevational view of the first crank weight of the crank shaft shown in FIG. 9.  
         [0068]    [0068]FIG. 12 is a side elevational view of the second crank weight of the crank shaft shown in FIG. 9.  
         [0069]    [0069]FIG. 13 is a side elevational view of the third crank weight of the crank shaft shown in FIG. 9.  
         [0070]    [0070]FIG. 14 is a side elevational view of the fourth crank weight of the crank shaft shown in FIG. 9.  
         [0071]    [0071]FIG. 15 is a sectional view of the conventional V-type engine assembled with selected connecting rods and pistons.  
         [0072]    [0072]FIG. 16 is a view explaining an ignition sequence of a V-type engine.  
         [0073]    [0073]FIG. 17 is a view explaining the directions and magnitudes of loads applied to respective bearing portions in a V-type engine. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0074]    Referring now to FIG. 1, a V-type engine  2  includes a first through an eighth cylinder (numbered #1 to #8, not shown). V-type engine  2  includes a V-shaped cylinder block  4  having a one-side cylinder bank  6 A and an opposite-side cylinder bank  6 B. Center line CA is the center line of one-side cylinder bank  6 A and center line CB is the center line of opposite-side cylinder bank  6 B. V-type engine  2  also includes a one-side cylinder head  8 A and an opposite-side cylinder head  8 B.  
         [0075]    V-type engine  2  includes a bearing construction member  10  having a crank case  12 . Bearing construction member  10  also includes a plurality of bearing caps  14 . A crank shaft  16  operates within V-type engine  2 , as will be explained. An oil pan  18  attaches to bearing construction member  10  and aids oil supply to V-type engin  2  during operation. Bearing construction member  10  includes crank case  12  integrated with bearing caps  14 .  
         [0076]    Additionally referring now to FIG. 2, cylinder block  4  includes a plurality of one-side cylinders  20 A and opposite-side cylinders  20 B.  
         [0077]    In an eight-cylinder cylinder block  4 , one-side cylinders  20 A include a first cylinder  20 A- 1 , a third cylinder  20 A- 3 , a fifth cylinder  20 A- 5 , and a seventh cylinder  20 A- 7 . One-side cylinders  20 A are aligned along the lengths of cylinder block  4 . Opposite-side cylinders  20 B include a second cylinder  20 B- 2 , a fourth cylinder  20 B- 4 , a sixth cylinder  20 B- 6 , and an eighth cylinder  20 B- 8 .  
         [0078]    Engine center line EC passes through the center of V-type engine  2  and bisects an angle α formed between opposite-side center line CB, center O, and one-side center line CA. Center O passes through the rotational center of a crank shaft  16 . Crank shaft  16  operates in a rotation direction R.  
         [0079]    One-side angle θ1 is between engine center line EC and one-side center line CA. Opposite-side angle θ2 is between engine center line EC and opposite-side center line CB. Angle c maybe any angle capable of allowing V-type engine to effectively operate but may preferably be 60°.  
         [0080]    During assembly, an upper surface of crank case  12  mounts on a lower surface of V-shaped cylinder block  4 . An attachment fitting (not shown) mounts oil pan  18  on a lower surface of crank case  12 . V-shaped cylinder block  4 , in cooperation with bearing construction member  10  and bearing caps  14 , rotatably supports crank shaft  16  in a length direction along V-type engine  2 .  
         [0081]    One-side and opposite-side cylinder heads  8 A and  8 B are secured on the upper surfaces of respective one-side and opposite-side cylinder banks  6 A and  6 B.  
         [0082]    In bearing construction member  10 , a plurality of lower mounting bolts  22  mount crank case  12  and bearing caps  14  to the lower surface of cylinder block  4 . A plurality of side mounting bolts  24  integrally hold crank case  12  and bearing caps  14  together along a side.  
         [0083]    Referring now to FIG. 3, crank shaft  16  includes a first through a fifth crank journal  26 - 1  to  26 - 5 . Crank journals  26 - 1  to  26 - 5  are spaced along a length of crank shaft  16 , as will be described.  
         [0084]    Crank shaft  16  also includes a first through an eighth crank pin  28 - 1  to  288 . Crank pins  28 - 1  to  28 - 8  correspond to respective first through eighth cylinders (#1 through #8, shown later) in V-type engine  2 .  
         [0085]    A pair of first crank weights  30 - 1 A and  30 - 1 B are formed on opposite sides of first crank pin  28 - 1 . A second crank weight  30 - 2  is between third crank pin  28 - 3  and fourth crank pin  28 - 4 . A third crank weight  30 - 3  is between fifth crank pin  28 - 5  and sixth crank pin  28 - 6 . A pair of fourth crank weights  30 - 4 A and  30 - 4 B are formed on opposite sides of eighth crank pin  28 - 8 .  
         [0086]    A first and a second crank arm  32 - 1 ,  32 - 2  are on opposite sides of second crank journal  26 - 2 . A third and a fourth crank arm  32 - 3 ,  32 - 4  are on opposite sides of third crank journal  26 - 3 . A fifth and a sixth crank arm  32 - 5 ,  32 - 6  are on opposite sides of fourth crank journal  26 - 4 . A pulley mounting projection  34  is on one end of crank shaft  16  adjacent first crank journal  26 - 1 . A starter motor gear  36  is on an opposite end of crank shaft  16  adjacent fifth crank journal  26 - 5 .  
         [0087]    A plurality of semi-circular block side shaft holes  38  extend through the lower surface of cylinder block  4  corresponding to respective crank journals  26 - 1  to  26 - 5  on crank shaft  16 .  
         [0088]    Referring now to FIG. 4, in contrast to shaft holes  38 , bearing caps  14  each have a plurality of case side bearing portions  42 , respectively first through fifth case side bearing portions  42 - 1  to  42 - 5 . During assembly, a plurality of semicircular case side shaft holes  40 , respectively a first through a fifth case side shaft hole  40 - 1  to  40 - 5 , receive respective crank journals  26 - 1  to  26 - 5  of crank shaft  16 .  
         [0089]    Crank shaft  16  receives rotation support from bearing metals  44  positioned between respective block side shaft holes  38  (of cylinder block  4 ) and case side shaft holes  40  (of bearing caps  14 ).  
         [0090]    A plurality of one-side connecting rods  46 A operate relative to one-side cylinders  20 A, as will be explained. A plurality of opposite-side connecting rods  46 A operate in respective opposite side cylinders  20 B, as will be explained. One-side connecting rods  46 A and opposite-side connecting rods  46 B each have a large end and a small end.  
         [0091]    A plurality of one-side connection bolts  50 A and one-side caps  48 A connect respective large ends of one-side connecting rods  46 A to respective crank pins  28  on crank shaft  16 . A plurality of opposite-side connecting bolts (not shown) and opposite-side caps (also not shown) connect respective large ends of opposite-side connecting rods  46 B to respective crank pins  28  on crank shaft  16 . This type of connective arrangement is clearly shown in FIG. 1, where third one-side connecting rod  46 A and fourth opposite-side connecting rod  46 B are shown in V-type engine  2 .  
         [0092]    A plurality of one-side piston pins  54 A pivotally connect the small ends of respective one-side connecting rods  46 A to a respective plurality of one-side pistons  52 A slidable in one-side cylinders  20 A. A plurality of opposite-side piston pins  54 B pivotally connect the small ends of respective one-side connecting rods  46 B to a respective plurality of opposite-side pistons  52 B, slidable in opposite side cylinders  20 B.  
         [0093]    In an eight-cylinder V-type engine  2 , the ignition sequences is as follows: first cylinder (#1), eighth cylinder (#8), fourth cylinder (#4), third cylinder (#3), sixth cylinder (#6), fifth cylinder (#5), seventh cylinder (#7), and second cylinder (#2). This ignition sequence is similar to conventional eight-cylinder V-type engines.  
         [0094]    A bulge portion  56  is formed on a front side of crank case  12 . Budge portion  56  extends away from V-shaped cylinder block  4 , along a block side wall  4 A. Budge  56  has a shape and a position which resists the horizontal shear stresses applied to crank case  12  (with bearing caps  14 ) generated along crank shaft  16  during operation.  
         [0095]    Budge portion  56  extends from a one-side case side wall  12 A opposite an opposite-side case side wall (shown but not numbered). Budge portion  56  extends in a direction along rotation direction R of crank shaft  16 . Budge portion  56 , as well as other elements in the present invention, are designed and positioned to minimize detrimental horizontal distortion and increase engine life.  
         [0096]    An oil pump  58  mounts on a lower surface of bulge portion  56 . Specifically, oil pump  58  mounts on a lower end of crank case  12  to reduce a total length of V-type engine  2 . Further, oil pump  58  is specifically located at a position extending outward from crank case  12  to prevent interference between oil pump  58  and crank shaft  16 .  
         [0097]    A first oil path  62  is formed on a Budge side wall  56 A of Budge portion  56 . First oil path  62  communicates with a discharge path  60  of oil pump  58 .  
         [0098]    A second oil path  66  is formed onto block side wall  4 A and communicates with both first oil path  62  as well as a main oil path  64 . Main oil path  64  is on V-shaped cylinder block  4 .  
         [0099]    First oil path  62  is on an oil path boss portion  68  that extends to, and communicates with, second oil path  66 . Oil path boss portion  68  is a portion of bearing construction member  10  and projects outward away from V-shaped cylinder block  4 . The position and design of oil path boss portion  68 , first and second oil paths  62 ,  66 , main oil path  64 , and Budge side wall  56 A all contribute to the horizontal rigidity of bearing caps  14 .  
         [0100]    To further resist horizontal deformation and increase rigidity, a plurality of first one-side and opposite-side boss portions  70 A,  70 B are on respective one-side and opposite side case side walls  12 A,  12 B. First one-side and opposite-side boss portions  70 A,  70 B are collectively referred to as first boss portions  70 .  
         [0101]    First one-side and opposite-side boss portions  70 A,  70 B are formed in positions selected to resist horizontal loads applied from crank shaft  16  to crank case  12  and bearing caps  14 .  
         [0102]    First one-side and opposite-side boss portions  70 A,  70 B are positioned on respective one-side and opposite-side case side walls  12 A.  12 B at spaced predetermined intervals.  
         [0103]    A plurality of reinforcing ribs  72  (represented as a plurality of one-side reinforcing rib  72 A) are disposed in an axial direction on crank case  12  and extend outward at positions relative to respective first boss portions  70 . Reinforcing ribs  72  serve to reinforce respective first boss portions  70 , crank case  12 , and resist horizontal distortion during engine operation.  
         [0104]    A plurality of second boss portions  74  are disposed on V-shaped cylinder block  4  at positions above selected first boss portions  70 .  
         [0105]    An engine mount bracket  80  includes an upper and a lower bracket portion  80 B,  80 A. Engine mount bracket  80  spans the joint between the lower surface of V-shaped cylinder block  4  and the upper surface of crank case  12  and aids in securing V-type engine  2  to a fixed point (not shown).  
         [0106]    A set of first tightening bolts  76  fixes lower bracket portions  80 A to selected first boss portions  70 . A set of second tightening bolts  78  fixes upper bracket portions  80 B to second boss portions  74 .  
         [0107]    First boss portions  70  are formed on respective one-side and opposite-side case side walls  12 A,  12 B at relatively lower positions on bearing construction member  10 . In contrast, second boss portions  74  are formed on block side wall  4 A of V-shaped cylinder block  4  at relatively higher positions.  
         [0108]    During operation of eight-cylinder V-type engine  2 , multiple loads are applied to crank shaft  16  and received by bearing caps  14 . These loads include loads from one-side pistons  52 A and one-side connecting rods  46 A. The loads also include loads from opposite-side pistons  52 B and opposite-side connecting rods  46 B.  
         [0109]    During one-side cylinder ignition, the loads from respective one-side cylinders  20 A pass along a vector on one-side cylinder center line CA. During opposite-side cylinder ignition, the loads from respective opposite-side cylinders  20 B pass a long a vector on opposite-side cylinder center line CB.  
         [0110]    Eight cylinder V-type  2  engine is effected by both the ignition sequence and the inertial forces of first through fourth crank weights  30 - 1  to - 4  in a manner different from four and six cylinder engines. For example, during ignition of V-type  2  engine, when the fourth cylinder is ignited, loads having horizontal components are applied to bearing caps  14 . As a second example, when the third cylinder is ignited, a similar horizontal load component is also applied to bearing caps  14 .  
         [0111]    Referring now to FIG. 5, fourth opposite-opposite side piston  52 B- 4  receives an explosion load along the direction of fourth opposite-side cylinder center line CB- 4 . At the same time, this load is applied to a respective bearing cap  14 . Simultaneously, an inertial force of third counter weight  30 - 3  (on crank shaft  16 ) is at least twice as large as an inertial force of second counter weight  30 - 2 .  
         [0112]    Upon the ignition of fourth opposite-side piston  52 B- 4 , a resultant force FK′ is applied horizontally along bearing caps  14 . Resultant force FK′ is obtained by adding a resultant force F 1 ′ (of a load W′ and an inertial force K 1 ′) to an inertial force K 2 ′. A similar phenomenon arises when ignition occurs in sixth opposite-side cylinder ( 20 B- 6 , not shown). Upon ignition of the sixth cylinder, a resultant force of an explosion load and the inertial force of fourth counter weight  30 - 4  (A and B combined) is applied horizontally through the affect of the above inertial force. The remaining loads are not substantially applied horizontally. A reader should note that bulge portion  56 , while serving multiple purposes, serves to brace bearing construction member  10  against resultant force FK′.  
         [0113]    As a benefit if the present design, to reduce the total length of V-type engine  2 , oil pump  58  is mounted to the lower end of bulge portion  56  projecting away from the side of crank case  12 . As a further design benefit to minimize interference with crank shaft  16 , oil pump  58  extends outward from crank case.  
         [0114]    To increase horizontal rigidity of bearing caps  14 , oil path boss portion extends outward from V-shaped cylinder block  4  and allows first oil path  62  to communicates with second oil path  66 .  
         [0115]    To further increase horizontal rigidity and minimize horizontal deformation in bearing construction member  10 , first boss portions  70  (with respective reinforcing ribs  72  on case side wall  12 A) are formed on crank case  12 .  
         [0116]    As a result of the present design, even where loads are applied in a horizontal manner relative to crank shaft  16 , engine vibration and noise can be reduced by reducing the clearances of case side shaft holes  40 - 1  to  40 - 5 . The clearances of case side shaft holes  40 - 1  to  40 - 5  is achievable by improving the rigidity of one-side case side wall  12 A and preventing deformation of lower mounting bolts  22 . The rigidity of one-side case side wall  12 A is enhanced through the interactive support of the elements noted above and from respective first and second boss portions  70 ,  74  and engine mount bracket  80 .  
         [0117]    As a further benefit of the present invention, it is not necessary to increase the wall thickness of case side wall  12 A of crank case  12 , to add additional supporting members to crank case  12 , or to change the material of crank case  12  to iron. These benefits reduce both weight and manufacturing costs.  
         [0118]    An additional benefit positions oil pump  58  at a location that minimizes the total length of V-type engine  2  and prevents interference with crank shaft  12 .  
         [0119]    Referring now to FIG. 6, a second embodiment of the present invention positions lower mounting bolts  22 - 1  and  22 - 2  in oblique positions directly along the horizontal loads applied to crank case  12  from crank shaft  16 . As in the previous embodiment, lower mounting bolts  22  mount crank case  12  on the lower surface of cylinder block  4 . In this embodiment, since the horizontal loads from crank shaft  16  are applied in axial directions respective to lower mounting bolts  22 , deformation is effectively prevented for both bearing caps  14  and respective case side shaft holes  42 .  
         [0120]    Referring now to FIG. 7, a third embodiment of the present invention includes a pump-mounting inclined surface  84 . Pump-mounting inclined surface  84  is substantially perpendicular to the horizontal loads applied from crank shaft  16  and is on the lower surface of crank case  12 . In the third embodiment, oil pump  58  mounts to pump-mounting inclined surface  84 . The position and thickness of pump-mounting inclined surface  84  increases the rigidity of crank case  12  and case side wall  12 A (not shown) and simplifies construction through elimination of additional linking members.  
         [0121]    Readers skilled in the art should note that, as is shown the referenced drawing, the ‘horizontal forces’ applied to deform respective V-type engines  2  are forces having a substantial horizontal vector or component and are so labeled for convenience only. Thus, the above invention is not limited to countering those forces applied in a solely horizontal manner but to those forces having an undesirable or damaging horizontal component.  
         [0122]    Although only a single or few exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiment(s) without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the spirit and scope of this invention as defined in the following claims. In the claims, means- or step-plus-function clauses are intended to cover the structures described or suggested herein as performing the recited function and not only structural equivalents but also equivalent structures. Thus, for example, although a nail, a screw, and a bolt may not be structural equivalents in that a nail relies entirely on friction between a wooden part and a cylindrical surface, a screw&#39;s helical surface positively engages the wooden part, and a bolt&#39;s head and nut compress opposite sides of at least one wooden part, in the environment of fastening wooden parts, a nail, a screw, and a bolt may be readily understood by those skilled in the art as equivalent structures.  
         [0123]    Having described preferred embodiments of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention as defined in the appended claims.