Abstract:
An improved oil pump drive arrangement and pressure relief valve therefore for an internal combustion engine. The oil pump is disposed externally of the engine around a shaft that extends through the body of the engine. This extending portion of the shaft drives at least one engine accessory through a pulley which axially overlaps and circumferentially surrounds the oil pump housing to provide a compact engine construction.

Description:
BACKGROUND OF INVENTION 
     This invention relates to an internal combustion engine and more particularly to an improved, compact and low cost oil pump arrangement for such engines. 
     Generally four-cycle internal combustion engines are lubricated by an oil pump that is generally positioned within the body of the engine and which is generally driven off of the crankshaft at one end thereof. Such constructions have some disadvantages, particularly when considering that it is also a conventional practice to embody the pressure relief system for the oil pump within the oil pump body. By positioning this part of the engine within the engine body, it tends to elongate the engine, particularly when the accommodation for the relief valve is considered. 
     With the modern space constraints placed upon internal combustion engines, particularly those for automotive applications, such increases in engine length are unacceptable or undesirable. 
     It is, therefore, a principal object to this invention to provide an improved, compact and simplified oil pump for an internal combustion engine. 
     It is a further object to this invention to provide an improved oil pump and relief arrangement for an engine that permits the engine to be compactly constructed. 
     SUMMARY OF INVENTION 
     This invention is adapted to be embodied in an internal combustion engine that comprises an engine body, which defines at least one combustion chamber in which a piston reciprocates. A shaft is driven by the reciprocation of the piston. The shaft has an end portion that extends beyond an outer wall of the engine body. A pulley is affixed to the shaft end portion for driving an engine accessory. An oil pump housing is affixed to the outer wall in surrounding relationship to the shaft end portion and containing a pumping element driven by the shaft end portion for pumping a lubricant for the engine. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a cross sectional view of an engine constructed in accordance with an embodiment of the invention taken along a transverse plane to the crankshaft axis. 
     FIG. 2 is a perspective, front view of the front or timing cover of the engine. 
     FIG. 3 is an enlarged front elevational view of the engine front cover in the area of the oil pump. 
     FIG. 4 is a cross sectional view taken along the line  4 — 4  of FIG.  3 . 
     FIG. 5 is a cross sectional view taken along the line  5 — 5  of FIG.  3 . 
     FIG. 6 is a cross sectional view taken along the line  6 — 6  of FIG.  3 . 
    
    
     DETAILED DESCRIPTION 
     Referring now in detail to the drawings and initially primarily to FIG. 1, an internal combustion engine constructed in accordance with an embodiment of the invention is indicated generally by the reference numeral  11 . Although the invention deals primarily with the construction and operation of its oil pump, which is shown in more detail in the remaining figures, the overall construction of the engine  11  will be described generally so as to permit those skilled in the art to understand an environment in which the invention can be practiced. Of course, the description of the basic engine components is for illustration only and those skilled in the art will readily understand how the invention can be utilized with a wide variety of types of engine constructions and engine configurations. 
     The engine  11 , in the illustrated embodiment, is of the V-type and accordingly is embodied in an engine having a cylinder block  12  having a pair of angularly related cylinder banks in which cylinder bores  1   3  are formed. In the specific embodiment illustrated, the engine  11  is of the V8 type and there are four cylinder bores  13  in each cylinder bank. 
     One end of each cylinder bank and specifically the cylinder bores  13  formed therein is closed by a respective cylinder head assembly  14 . These cylinder head assemblies  14  have recesses  15  formed in their lower surfaces that cooperate with the cylinder bores  13  and pistons  16  reciprocating therein to form the combustion chambers of the engine. 
     The pistons  16  are connected by piston pins to the upper or small ends of respective connecting rods  17 . The connecting rods  17  are, in turn, journalled on the throws of a crankshaft  18 . 
     The crankshaft  18  is rotatably journalled in a crankcase assembly  19  which is comprised of the skirt of the cylinder block  12 , an oil pan and bearing forming member  21  and an oil pan  22  that is affixed to the underside thereof and which defines an oil reservoir in which lubricant for the engine is contained. 
     The engine  11  is preferably, but not necessarily, liquid cooled and to this end, the cylinder block  12  is provided with a cooling jacket  23  and the cylinder head assemblies  14  are provided with cooling jackets  24 . Coolant is circulated through these cooling jackets  23  and  24  by a coolant pump of a known type in any suitable manner. 
     An induction system is provided for supplying at least an air charge to the combustion chambers of the engine. This induction system includes a plenum chamber device  25  which is disposed above one of the cylinder banks and specifically the cylinder head assembly  14  thereof and which has a suitable atmospheric air inlet. This atmospheric air inlet may include a filtering and silencing device as well as a throttle body for controlling engine speed. 
     The plenum chamber device  25  serves an intake manifold, indicated generally by the reference numeral  26 , that has discharge ends which communicate with intake passages  27  formed in the valley side of the cylinder head assemblies  14 . These intake passages  27  are valved by intake valves  28  that are slidably mounted in the cylinder head assemblies  14 . These intake valves  28  are urged to their closed position by means of coil compression spring assemblies  29 . The intake valves  28  are opened by the lobes  31  of respective intake camshafts  32  that are journalled in the cylinder head assembly  14  in an appropriate manner. These camshafts  32  are covered by cam covers  33  that are affixed to the respective cylinder heads. 
     The cam lobes  31  cooperate with thimble tappets  34  that are interposed between the cam lobes  31  and the stems of the intake valves  28  in a manner well known in this art. The intake camshafts  32  are driven at one half the rotational speed of the crankshaft  18  by any suitable cam shaft driving arrangement. 
     Fuel injectors  35  are mounted in the cylinder head assemblies  14  for injecting fuel into the intake passages  27  for delivery to the engine combustion chambers. The admitted fuel charge is ignited by means of spark plugs  36  that are mounted centrally in the engine combustion chambers by the cylinder head assemblies  14 . 
     The charge which is admitted to the combustion chambers and ignited by the spark plugs  36  will expand and then be discharged through exhaust passages  37  formed in the cylinder head assemblies  14  on the sides away from the valley and opposite to the intake passages  27 . These exhaust passages  37  communicate with exhaust manifolds  38  fixed to the outer surface of the cylinder head assemblies  14 . These exhaust manifolds  38  communicate with any suitable type of exhaust system. 
     The flow through the exhaust passages  37  is controlled by exhaust valves  39  that are mounted in the cylinder head assemblies  14  and which like the intake valves  28  are urged to their closed position by coil spring assemblies  41 . The exhaust valves  39  are opened by means of lobes  42  of exhaust camshafts  43  that are also journalled by the cylinder head assemblies  14  and enclosed within the cam chambers defined by the valve covers  33 . 
     The lobes  42  act upon thimble tappets  44  for opening the exhaust valves  39  in a well known manner. Like the intake camshafts  32 , the exhaust camshafts  43  are driven at one half-crankshaft speed by a suitable cam timing drive. 
     The construction of the engine  11  as thus far described may be considered to be conventional and, for the reasons already noted, further discussion of its detailed construction except for the oil pump, which will be described shortly, is not believed to be necessary to permit those skilled in the art to practice the invention. 
     The invention deals with the oil pump, which is shown, in most detail in FIGS. 2-6 but before referring these figures, it should be noted that the oil pump draws oil from the oil pan  22  through a strainer  45  and pick up tube  46 . The pick up tube  46  delivers oil to the oil pump in a manner, which will be described shortly. 
     Referring now to FIGS. 2-6, it has been mentioned that the camshafts  32  and  43  are driven by a suitable timing drive and that drive is positioned at the front end of the engine as seen in FIG.  6  and which may include a timing chain  47  that is driven by a sprocket mounted on the crankshaft  18 . This timing chain  47  is disposed outwardly of a front end wall  48  formed in the main engine body and primarily the cylinder block  12  and which is closed by a timing case cover  49  which forms the outer peripheral edge at one end of the engine body. This timing case cover  49  is affixed to the cylinder block  12  in a suitable manner and is shown in more detail in FIG.  2 . 
     Referring specifically to FIGS. 2,  4  and  6 , the timing case cover  49  is provided with an opening  51  through which one end of the crankshaft  18  extends. A pulley  52  is affixed to this extending crankshaft end portion for driving one or more engine accessories and other pulleys. This is conventional practice. However, and in accordance in accordance with the invention, an oil pump assembly, indicated generally by the reference numeral  53 , is positioned within the hollow interior of the drive pulley  52  and on the outer front face of the timing cover  49  or front end wall of the engine  11 . 
     The oil pump assembly  53  is formed in part by a circumferentially extending flange  54  of the timing cover  49  which flange receives a pump cover  55 . An O-ring seal  56  is provided around the flange  54  for providing an oil tight seal in this area. The pump cover  55  has an end wall  57 , which receives a seal  58  around the crankshaft end and inwardly from the point where the pulley  52  is affixed. 
     The oil pump  53  is of the trochoidal type, although other types can be utilized, and has a driving member  59 . This driving member  59  is suitably coupled to the portion of the end of the crankshaft  18  that extends into the pump cover  55  and cooperates with the pump cover  55  to draw oil from the tube  46  through a passageway  61  formed in the cylinder block  12  and a corresponding passageway  62  (FIG. 6) formed in the timing cover  49 . This oil then enters the oil pump  53  through an opening  63  formed in the timing cover  49  radially outwardly of the opening  51  that passes the crankshaft  18 . 
     The oil pumped by the oil pump  53  is then delivered through a supply passageway  64  (FIGS. 3-5) formed in the timing cover  49  and from there to an arcuate passageway  65  that is also formed in the rear side of the timing cover  49 . The outer side of this passageway  65  is closed by a closure plate  66  that is affixed in a suitable manner to the timing cover  49  in overlying relationship to the passageway  65 . The passageway  65  is intersected by a drilled passageway  67  which is, in turn, communicates with the supply passageway  64  of the timing cover  49 . The outer end of the supply passageway  64  is closed by a sealing ball  68 . 
     The passageway  65  delivers the pumped lubricant to a further drilled passageway  69  formed in the timing cover  49  which communicates with a pressure relief valve  71  that is slidably supported in a drilled passageway  72  also formed in the timing cover  49 . The outer end of this passageway  72  is closed by a closure member  73 . A coil compression spring  74  normally urges the relief valve  71  to a closed position wherein communication with a small bypass port  75  is precluded. The bypass port  75  is also formed in the timing cover  49 . This bypass port  75  communicates back with the inlet side of the pump  53  or with the oil pan  22 , depending upon the preference of the designer. 
     The passageway  69  also communicates with a main oil gallery  76  that is formed in the cylinder block  12  and which serves to distribute lubricant to the engine  11  for its lubrication in any well known manner. 
     Thus, from the foregoing description, it should be readily apparent that the oil pump  53  is positioned externally of the main engine body and specifically the cylinder block  12  and oil pan  22  and thus, permits shortening of the internal portion of the engine. Because the oil pump  53  is nested within the drive pulley  52  it also does not add to the overall length of the engine. Furthermore, a simpler construction is possible and thus the engine can be made more compact and yet the lubrication system very easily manufactured. Of course, the foregoing description is that of a preferred embodiment of the invention and various changes and modifications may be made without department from the spirit and scope of the invention, as defined by the appended claims.