Abstract:
An engine cylinder block formed with an integral pump housing that reinforces the cylinder block and which has a communicating passage with the interior of the cylinder block that has an outer surface that is inclined upwardly of the cylinder block to permit gasses to escape during a casting process to avoid metallic voids from forming. In addition the block is further reinforced by longitudinal and vertical external ribs.

Description:
BACKGROUND OF INVENTION  
       [0001]     This invention relates to a cylinder block for an internal combustion engine and more particularly to an improved, cylinder block casting having an integral pump cavity formed therein.  
         [0002]     Frequently engine cylinder blocks are formed by a casting process and include one or more integrally formed pumping cavities that contain pumping elements for circulating a liquid necessary for the engine operation such as for a coolant pump. A typical arrangement of this type is shown in Japanese Published Application JP-A-2001-65354. As seen in this publication, the cylinder block has a cylinder block body having a plurality of cylinder bores formed along the axial length thereof that are surrounded by cooling jackets. The casing of a cooling pump for delivering coolant projects outwardly from a side of the cylinder block. By forming the pump body integrally with the cylinder block the construction in made simpler and as an added benefit, the cylinder block is strengthened as the integral pump adds to its rigidity.  
         [0003]     However with the prior art structures of this type another problem arises. That is when the pump casing is formed integrally with the cylinder block body the horizontally extending passage communicating the pumping cavity with the communicating cylinder block cavity can form a trap that blocks the free passage of the molten metal during the casting process and voids can develop that may be difficult to detect. In any event, these voids can result in scrappage that adds to the cost.  
         [0004]     It is therefore a principle object of the invention to provide a effective and sound casting for a cylinder block that incorporates an integral pump.  
         [0005]     It is a further object of the invention to provide an integral cylinder block and pump having high rigidity.  
       SUMMARY OF INVENTION  
       [0006]     This invention is adapted to be embodied in a cylinder block for an internal combustion engine having a lower, crankcase receiving portion and an upper, cylinder head receiving portion. At least one cylinder bore is formed in the cylinder block extending between its lower and upper portions and surrounded at least in part by a coolant jacket. A pump receiving portion is formed at one side of the cylinder block and has a communication passage communicating with a corresponding passage formed in the cylinder block. In accordance with the invention, the communication passage has an upper wall that in inclined upwardly from the pump receiving portion toward the upper portion of the cylinder block to facilitate casting of the cylinder block without the formation of unwanted metal voids. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0007]      FIG. 1  is a front elevational view of an internal combustion engine embodying a cylinder block in accordance with the invention.  
         [0008]      FIG. 2  is a front elevational view, in part similar to  FIG. 1 , but with the engine timing cover removed.  
         [0009]      FIG. 3  is a side elevational view of the engine.  
         [0010]      FIG. 4  is a front elevational view, in part similar to  FIGS. 1 and 2 , but shows only the cylinder block in solid lines with the cylinder head and bulkhead being shown in phantom for reference.  
         [0011]      FIG. 5  is a side elevational view, in part similar to  FIG. 3 , but shows only the cylinder block in solid lines with the remainder of the engine being shown in phantom for reference.  
         [0012]      FIG. 6  is a top plan view of the cylinder block with the fully assembled coolant pump and its drive.  
         [0013]      FIG. 7  is a cross sectional view taken through the rotational axis of the coolant pump.  
         [0014]      FIG. 8  is a side elevational view, in part similar to  FIG. 5 , but showing the opposite side of the cylinder block.  
         [0015]      FIG. 9  is a cross sectional of the cylinder block taken along the line  9 - 9  in  FIG. 6  with the bulkhead and cylinder head being shown partially and in phantom for reference. 
     
    
     DETAILED DESCRIPTION  
       [0016]     Referring now in detail to the drawings and initially primarily to  FIGS. 1-3 , a multi-cylinder, four-stroke internal combustion engine embodying the invention is indicated generally by the reference numeral  11 . In the illustrated embodiment the engine  21  is shown as having four in line cylinders. Of course, from the following description it will be obvious to those skilled in the art, that the invention can be utilized with engines having other numbers of cylinders and other engine configurations. In addition the invention is not limited to engines operating on the four stroke principle.  
         [0017]     The engine  21  is adapted to be mounted on and power a vehicle such as an automobile and is depicted as being mounted vertically therein, although the invention is not so limited. The engine  21  has an engine body, indicated generally at  22  supported in a suitable fashion by a vehicle body (not shown).  
         [0018]     The engine body  22  is comprised of a cylinder block, indicated generally at  23 , and cast in a manner to be described. The cylinder block  23  is formed with four cylinder bores  24  having parallel axes  25 . Detachably affixed, in a known manner, to the lower end of the cylinder block  23  is a bulkhead  26  to form the upper portion of a crankcase.  
         [0019]     A cylinder head assembly  27  is secured to the upper face of the cylinder block  23  in a known manner and closed the upper ends of the cylinder bores  24 . The cylinder head assembly  27  supports valves for controlling the admission of a charge into the engine combustion chambers and the discharge of exhaust gasses therefrom in any suitable manner and as is well known in this art. These valves are operated in a manner to be described. This valve and operating mechanism is enclosed by a cylinder head cover  28  that is secured to the upper face of the cylinder head  27 .  
         [0020]     The aforedescribed crankcase, the upper portion of which is formed by the bulkhead  26  is completed and closed by an oil pan  29  that is suitably secured to the lower face of the bulkhead  26  and contains lubricating oil.  
         [0021]     The engine  21  is provided with pistons  30  reciprocating in the cylinder bores  24  and connected by connecting rods  40  to drive a crankshaft  31 . The crankshaft  31  rotates about an axis  32  that extends generally horizontally. The crankshaft  31  is journalled about this axis  32  by bearings carried by the cylinder block  23  and bulkhead  26  in a manner well known in the art.  
         [0022]     The aforedescribed intake and exhaust valves are operated in a suitable manner by a valve actuating mechanism, indicated generally at  33 . This valve actuating mechanism  33  is comprised of an intake camshaft  34  and an exhaust camshaft  35  in suitable operational engagement with the intake valves and exhaust valves, respectively. The camshafts  34 ,  35  haves axes that extend parallel to the axis  32  of the crankshaft  31 . A timing chain  36  for interconnects one end of the crankshaft  31  with the ends of the camshafts  34 ,  35  to drive them in timed relation at one half the rotational speed thereof.  
         [0023]     As has been noted, the cylinder block  23  is made by casting, and preferably of low pressure cast aluminum. The cylinder block generally comprises a cylinder block body, indicated generally at  37 , comprised primarily of a body portion  38  having a generally cubic shape and in which the plurality of cylinder bores  24  are formed. The body portion  38  also has upper and lower faces  39 . The upper face  39  is in suitable sealing contact with the lower face of the cylinder head  27 . In a like manner, the lower face  39  is in suitable sealing contact with the upper face of the bulkhead  26 .  
         [0024]     The engine  21  is provided with a cooling system, indicated generally at  41 , for cooling the engine body  22  with a suitable coolant. The cooling system  41  is comprised of with coolant jackets  42  formed around the cylinder bores  24  in the cylinder block body  37 . In addition the cooling system  41  includes a coolant pump, indicated generally by the reference numeral  43 , supported on the lateral face of the cylinder block body  37  and capable of delivering the coolant to the coolant jackets  42 . The cooling system also includes a pump drive, to be described shortly, a radiator (not shown) for cooling the coolant after having been delivered to the coolant jackets  42  and a thermostat  44  ( FIG. 3 ) for controlling the temperature of the coolant.  
         [0025]     As shown in  FIGS. 1-4 ,  6  and  7 , the coolant pump  43  is provided with an outer casing, indicated generally at  45  formed in part integrally with and supported by the cylinder block body  37 . As best seen in  FIGS. 6 and 7 , a pump drive shaft  46  is supported by a closure  47  of the casing  45  via a bearing  48  for rotation about an axis  49  extending in parallel with the axis  32  of the crankshaft  31 . An impeller  51  is disposed in a pump chamber in the casing  45  and supported for rotation about the axis  49  on an end of the pump drive shaft  46 .  
         [0026]     As seen in  FIG. 7 , the pump casing  45  integrally protrudes forwardly from the outer lateral face at one end of the body portion  38  of the cylinder block body  37 . Thus the pump casing  45  is also made of low pressure cast aluminum.  
         [0027]     As seen in  FIGS. 1 and 7 , the pump shaft  46  and impeller  51  are provided with a pulley  52  that is driven from a pulley  53  fixed to the outer end the crankshaft  31  by a V-belt  54 . This belt  54  also may drive further engine or vehicle auxiliaries.  
         [0028]     As shown in  FIGS. 4, 6  and  7 , the casing  45  defines the pump chamber, which is in a spiral shape as viewed along the axis  32  of the crankshaft  31  and the axis  49  of the pump drive shaft  46 . As already noted, the pump drive shaft  46  is journalled on the bearing  48  carried by the closure  47 . This closure  47  is received in a circular insertion opening  55  formed in the front face of the casing  45  coaxially with the axis  49 . The insertion opening  55  allows insertion of the impeller  51  in the direction of the axis  49 . The inner side of the front face of the pump casing  45  is in the form of a spiral, in which the distance to the axis  49  of the impeller  51  gradually increases in a counterclockwise direction. Thus, the radial distance from the inner surface of the outer to the opening edge of the insertion opening  55  becomes increasingly greater in this direction.  
         [0029]     As best seen in  FIG. 7 , the casing  45  is provided with a discharge duct  56  with a closed rectangular cross section integrally protruding from the upper part of the casing body  45  toward the cylinder block body  37 . The protruding end of the discharge duct  56  is integrally joined to the lateral face of the cylinder block body  37 . The upper part of the pump chamber containing the impeller  51 , an internal passage  57  formed in the discharge duct  56 , and the coolant jackets  42  thus communicate with each other. The internal passage  57  of the discharge duct  56  has a cross section which gradually increases toward the cylinder block body  37 . The discharge duct  56  has an upper surface  58  forming the upper part of the casing  45  that is inclined upward from the protruding end of the casing  45  toward the cylinder block body  37 . The outer lateral face of the cylinder block body  37  and the casing  45  are integrally joined to each other over almost the entire contact area in the vertical direction of the cylinder block body  37 , whereby the cylinder block body  37  is significantly reinforced.  
         [0030]     In addition to the reinforcing of the cylinder block  23  by the integration of the coolant pump outer casing  45  and as shown in  FIGS. 5, 6 ,  8  and  9 , the engine body  22  is provided with integral, horizontal reinforcing ribs  59  that protrude outward from opposite sides of the cylinder block body  37  at approximately the vertical midsection. These horizontal ribs  59  are joined by integral vertical reinforcing ribs  61  located generally in the same axial positions as the axes  25  of the cylinder bores  24  and formed integrally with the upper outer lateral face of the cylinder block body  37  and the upper faces of the horizontal ribs  59 . As best seen in  FIG. 9 , the vertical ribs  61  taper as indicated at  62  inwardly in the vertical direction so as to assume a right-angled triangle shape when as viewed in the direction of the axis  32  of the crankshaft  31 .  
         [0031]     Because of the described configuration, when producing the cylinder block  23  by low pressure casting, as molten metal fills up the space corresponding to the coolant pump casing  45  within a mold formed by an outer frame and a sand core in a shape corresponding to the cylinder block  23 , the gas in the space corresponding to the upper part of the casing  45  is smoothly directed to the space corresponding to the cylinder block body  37  since the upper surface  58  of the casing  45  is inclined upward toward the cylinder block body  37 . Thus the molten metal is prevented from being trapped in the space corresponding to the upper part of the casing  45  and thus producing voids. Thus, it is possible to t produce a high-quality cylinder block  23 . Also since the upper surface  58  of the coolant pump casing  45  is inclined upward toward the cylinder block body  37 , the coupling area between the cylinder block body  37  and the coolant pump casing  45  in the vertical direction is enlarged as compared with when the upper surface  58  extends horizontally toward the cylinder block body  37 . Thus, the cylinder block body  37  is reinforced by the casing  45  for the coolant pump  43  effectively, and the strength of the cylinder block  23  is increased.  
         [0032]     The rigidity of the cylinder block  23  is further increased by the horizontal ribs  59  integrally protruding outward from the vertical midsection of the outer lateral face of the cylinder block body  37 , and the vertical ribs  61  located generally in the same positions as the axes  25  of the cylinder bores  24  in the axial direction of the crankshaft  31  Thus the portions of the cylinder block body  37  which tend to have lower strength because of the cylinder bores  24 , among the portions other than the portion with which the casing  45  is formed integrally, are reinforced by the horizontal ribs  59  and, in particular, the vertical ribs  61 . Thus, the strength of the cylinder block  23  can be reasonably improved so that every part of it can have uniform strength.  
         [0033]     Of course those skilled in the art will readily understand that the described embodiments are only exemplary of forms that the invention may take and that various changes and modifications may be made without departing from the spirit and scope of the invention, as defined by the appended claims. For examples only, the engine  21  may be a two-stroke engine and/or the axes  25  of the cylinder bores  24  may be inclined with respect to the vertical. Also the discharge duct  56  may have a circular cross section.