Patent Publication Number: US-8122867-B2

Title: Engine with oil pump muffler and noise damper

Description:
TECHNICAL FIELD 
     This invention relates to engines with front mounted oil pumps and to a muffler for absorbing noise from such oil pumps and for damping noise vibrations of an associated engine front cover. 
     BACKGROUND OF THE INVENTION 
     The present invention pertains to an engine having a cylinder block with a crankshaft driven oil pump mounted on the front of the block. The oil pump is enclosed within an engine front cover secured to the front of the block and also enclosing other components carried by the cylinder block. Operation of the oil pump in engine operation creates noise, which is radiated to the front cover and adds to the level of noise transmitted from the engine cover. A common method of noise reduction is to add external acoustical treatments to the cover. However, a more effective alternative solution is desired. 
     SUMMARY OF THE INVENTION 
     The present invention provides a novel wrap-around cover or noise muffler to cover the front and sides of a front mounted oil pump. The muffler absorbs noise vibrations and reduces the transfer of noise frequencies from the oil pump to an engine front cover that covers the pump. Additionally, the front of the muffler is shaped to fill the gap and engage the front cover in compression between the oil pump and the rear surface of the front cover, thereby damping vibrations of the front cover adjacent to the oil pump and the accessory drive pulley that rotates ahead of the front cover for driving a water pump and other accessories. 
     The scope of the invention also includes the oil pump and noise muffler assembly, which can be produced and shipped as a unit for engine installation. The engine, with the block mounted oil pump and engine front cover with the oil pump noise cover between them for noise absorption and damping noise vibrations in the cover is also within the inventive concepts. 
     These and other features and advantages of the invention will be more fully understood from the following description of a specific embodiment of the invention taken together with the accompanying drawings. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric front view of a lower portion of an engine block having a crankshaft driven oil pump mounted on the front of the block; 
         FIG. 2  is an isometric rear view of a lower portion of an engine front cover mountable on the block to enclose the oil pump and other components; 
         FIG. 3  is an isometric exploded view of an oil pump and muffler assembly for mounting on the block; 
         FIG. 4  is an isometric cross-sectional view from a vertical plane through the crankshaft axis and showing the left side portion of the engine front cover and the associated pump and muffler assembly looking from the front and right side of the assembly; and 
         FIG. 5 . is a cross-sectional view from a vertical plane through the crankshaft axis showing the right side of the engine front cover, oil pump and muffler assembly and the engine block front end mounting the pump. 
     
    
    
     DESCRIPTION OF AN EXEMPLARY EMBODIMENT 
     Referring now to  FIG. 1  of the drawings in detail, numeral  10  indicates an automotive engine block shown as an isometric front view of a pertinent lower portion  12  of the block  10  having a front wall  14 . An engine oil pump  16  is mounted to the engine block front wall  14  by bolts  18  at laterally opposite ends of the pump  16 . A muffler and noise damper  20  covers the front and sides of the pump  16  for noise reduction, as will be subsequently discussed. The oil pump  16  has a central opening  21  centered on a rotational longitudinal axis  22  ( FIG. 5 ) of the crankshaft, not shown. The crankshaft axis  22  also locates a vertical plane, not shown, extending through the crankshaft axis  22  and referred to regarding  FIGS. 4 and 5 . The periphery  24  of the block front wall  16  includes mounting openings  26  for receiving bolts or studs for mounting of an engine front cover  28  ( FIG. 2 ) on the front wall of the block  10  and an associated oil pan, not shown. The cover  28  and the block  10  with the oil pan enclose the oil pump  16 , muffler  20  and other components, not shown, mounted on the block front wall  14 . 
       FIG. 2  is an isometric view of a lower portion of the rear side  30  of the engine front cover  28  corresponding to the lower portion  12  of the engine block  10 . Peripheral portions  32  of the front cover  28  are provided with bosses  34  for receiving bolts or studs for mounting of the cover  28  on the front wall  14  of the engine block  10  and the oil pan, not shown. An annular recessed portion  36  of the cover front wall  38  has a central opening  40  mounting an oil seal  42  for sealingly engaging an end of the crankshaft, not shown. The crankshaft end, when installed, extends through the opening  40  for mounting an accessory drive pulley, not shown, close to the front wall  38  of the front cover  28 . When the front cover  28  is mounted on the engine block  10 , the block mounted oil pump  16  and muffler  20  extend into the recessed portion  36  of the engine cover front wall  38 . 
       FIG. 3  is an isometric exploded view of an oil pump and muffler assembly  44  in accordance with the invention. Assembly  44  includes the oil pump  16  with the slip-on noise cover or muffler  20  fitted over the front  48  and peripheral sides  50  of the pump  16  as previously described. The muffler  20  is formed of a sound absorbing and resilient elastomer such as, but not limited to, AR-12 Polyacrylate. The muffler  20  includes a relatively thick front wall  52  that covers the front  48  of the oil pump  16 . The muffler  20  also includes longitudinal peripheral sides  54  extending from the front wall  52  and closely surrounding the edges or peripheral sides  50  of the oil pump  16 . If desired, the sides  54  of the muffler  20  may include lips  56  that slide over the pump sides  50  and act to retain the muffler  20  on the pump  16  as a complete assembly  44 , ready for attachment to the engine block front wall  14 . 
       FIG. 4  is an isometric cross-sectional view from the vertical plane through the crankshaft axis  22  and showing the left side portion of the engine front cover  28  and the associated pump and muffler assembly  44  looking from the front and right side of the assembly. Visible in the drawing, starting from the back, are the oil pump  16 , the muffler  20  enclosing the pump, and the engine front cover  28 . Also shown are the central opening  21  and an inner rotor or gear  58  adapted to be driven by the crankshaft, not shown. The front  48  of the pump is engaged by the front wall  52  of the muffler  20  and the pump sides  50  are engaged by the sides  54  of the muffler to absorb noise vibrations or frequencies generated by the pump  16  and blocked by the muffler  20 . 
     The thick front wall  52  of the muffler  20  is also designed to engage the adjacent rear side  30  of the cover front wall  38  in compression sufficient to damp vibrations of the engine front cover  28 , which would otherwise result from noise frequencies carried to the front cover  28  from the pump  16  and other noise sources behind the cover  28 . In this function, the muffler front wall  52  acts as a resilient damper, reducing vibrations of the front cover adjacent to the oil pump  16  and limiting the radiation of noise from the lower portion of the front cover  28 . 
     Finally,  FIG. 4  illustrates the outside surface  60  of the front cover which is configured to maintain a minimum clearance from the external accessory drive pulley, not shown, that rotates just forward of the front cover  28 . Some of the cover attaching bolts  62  are also shown in  FIG. 4 . 
       FIG. 5 . is a cross-sectional view from the vertical plane through the crankshaft axis  22  showing the lower right side of the engine front cover  28 , the oil pump and muffler assembly  44 , including the oil pump  16  and the noise muffler  20 , and the engine block front wall  14  to which the oil pump  16  is mounted. The mounting features of the pump  16  are not shown in this view, as they are located at the lateral ends of the pump. Compressive engagement of the muffler front wall  52  with the engine front cover  28  is clearly shown, as are the front wall  52  and sides  54  of the muffler covering the front  48  and sides  50  of the pump. The cover oil seal  42  is also shown. 
     While the invention has been described by reference to certain preferred embodiments, it should be understood that numerous changes could be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the disclosed embodiments, but that it have the full scope permitted by the language of the following claims.