Abstract:
A damper that shears a fluid to dampen rotational force fluctuations and moves a plurality of masses within a fluid to dampen dynamic loading force fluctuations. The damper includes a case, a ring, a plurality of pockets, a mass, and a fluid. The case at least partially defines a case fluid cavity containing the fluid. The pockets are in the ring and the masses are in the pockets.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure relates to dampers, and more particularly to dampers for engine crankshafts and other rotating components. 
       BACKGROUND 
       [0002]    Engine crankshafts and other rotating components may experience fluctuations in loading or motion. These fluctuations may come from a variety of sources. Some fluctuations may occur from natural resonance forces of the rotation and other fluctuations may occur from direct loading or vibrational forces. 
         [0003]    Dampers may be added to the crankshaft to absorb the fluctuations and smooth the engine&#39;s operation and thereby reduce stress on the crankshaft. However, different damper designs may be suited for different sources of fluctuations. 
         [0004]    U.S. Pat. No. 6,026,776 (the &#39;776 patent) shows a damper incorporated into a counter balance of the crankshaft. The damper of the &#39;776 patent incorporates inertial masses inside bores in the counter balance. The inertial masses of the &#39;776 patent float in a damping medium contained in the bore. 
       SUMMARY 
       [0005]    In one aspect, the present disclosure provides a damper including a case, a ring, a plurality of pockets, a plurality of masses, and a fluid. The case at least partially defines a case fluid cavity containing the fluid. The pockets are in the ring and the masses are in the pockets. In another aspect, the present disclosure provides a crank assembly and the damper. 
         [0006]    In still another aspect, the present disclosure provides a method of damping fluctuations in motion of a rotating body. The method includes shearing a fluid to dampen rotational force fluctuations. The method also includes moving a plurality of masses within a fluid to dampen dynamic loading force fluctuations. 
         [0007]    Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a side view of an engine including a damper on a crank assembly; 
           [0009]      FIG. 2  is a side view of the crank assembly; 
           [0010]      FIG. 3  is a perspective view of the damper shown to include a case, a cover, and a hub; 
           [0011]      FIG. 4  is a cross-sectional view of the damper in  FIG. 3  showing the damper to include a ring, masses, a bearing, and a fluid; and 
           [0012]      FIG. 5  is a front view of the damper rotating with the cover removed for illustrative purposes. 
           [0013]      FIG. 6  is a front view of an alternative damper rotating with the cover removed for illustrative purposes. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    As seen in  FIG. 1 , an engine  10  includes a top end  12 , block  14 , oil pan  16 , and crank assembly  18 . The top end  12  is mounted or coupled to the top of the block  14  and the oil pan  16  is mounted or coupled to the bottom of the block  14 . The crank assembly  18  extends across the block  14  from an engine front  20  to an engine rear  22 . 
         [0015]    The engine  10  may include other features not shown, such as fuel systems, air systems, cooling systems, peripheries, drivetrain components, turbochargers, etc. The engine  10  may be any type of engine (internal combustion, gas, diesel, gaseous fuel, natural gas, propane, etc.), may be of any size, with any number of cylinders, and in any configuration (“V,” in-line, radial, etc.). The engine  10  may be used to power any machine or other device, including on-highway trucks or vehicles, off-highway trucks or machines, earth moving equipment, generators, aerospace applications, locomotive applications, marine applications, pumps, stationary equipment, or other engine powered applications. 
         [0016]      FIG. 2  shows the crank assembly  18  may include a crankshaft  24 , a flywheel  26 , drive sprockets  28 , a pulley  30 , and a damper  32 . The crankshaft  24  includes a crankshaft rear portion  34 , a crankshaft front portion  36 , and a crankshaft middle portion  38  extending between. The crankshaft rear portion  34  and crankshaft front portion  36  may extend outside of the block  14 . 
         [0017]    The crankshaft middle portion  38  may include journals  40  that are coupled with the engine&#39;s  10  connecting rods and pistons. Supporting the journals  40  are webs  42 . Counter weights  44  may also be included in the crankshaft  24  for balancing and to prevent vibration. 
         [0018]    The flywheel  26  may be coupled to the crankshaft front portion  36 . The flywheel  26  is used to drive a transmission, generator, or other engine  10  application. The drive sprockets  28  may be included to drive a camshaft, oil pump, or other engine  10  component through a chain or belt. The drive sprockets  28  may be located at either the crankshaft rear portion  34  or the crankshaft front portion  36 . The pulley  30  may be coupled to the crankshaft rear portion  34 , opposite the flywheel  26 . The pulley  30  may be used to drive various engine  10  systems or peripheries, such as power steering pumps, air conditioner pumps, water pumps, alternators, or fans, through a belt. The crank assembly  18  may include one or more pulleys  30 . 
         [0019]    The damper  32  is shown coupled to the crank assembly  18  outside the block  14  and to the rear of the pulley  30 . In other embodiments, the damper  32  may be included in various other locations on the crank assembly  18  outside the block  14 . The damper  32  may be on either side of the pulley  30  or other part of the crankshaft rear portion  34 . The damper  32  may also be located on the crankshaft front portion  36 , on either side of the flywheel  26 . In yet other embodiments, the damper  32  may be located within the block  14  on the crankshaft middle portion  38 . The damper  32  may be located on either side of or between the drive sprockets  28 . The damper  32  may also be located besides or partially within the webs  42  or counter weights  44 . The damper  32  may also be oriented with its front or rear facing block  14 . Alternative embodiments also contemplate that the damper  32  may be integral with or formed as a part of the pulley  30  or drive sprockets  28 . 
         [0020]      FIG. 3  shows the damper  32  may include a case  46 , a cover  48 , and a hub  50 . The hub  50  may be a disk member including bolt holes  52  through which bolts may be used to couple the damper  32  to the crank assembly  18 . The damper  32  may be coupled to the crankshaft  24 , pulley  30 , flywheel  26 , or other crank assembly  18  component. The damper  32  may also be coupled to the crank assembly  18  in a variety of other ways, including welding and other joining techniques. 
         [0021]    The case  46  is a disk shaped member coupled to the periphery of the hub  50 . The cross-sectional view in  FIG. 4  shows the case  46  to have a “C” shaped cross section and include a side portion  56 , outer lip portion  58 , and inner lip portion  59 . The side portion  56  extends from the inner lip portion  59  to the outer lip portion  58 . The outer lip portion  58  and inner lip portion  59  extend at an angle from the ends of the side portion  56 . The disk shaped cover  48  is coupled to a case end  54  of the outer lip portion  58  and the inner lip portion  59  in a fluid tight manner. 
         [0022]      FIG. 4  shows the damper  32  to also include a bearing  60 , a ring  62 , masses  64 , and a fluid  66 . The bearing  60  is supported by and surrounds the inner lip portion  59  of the case  46 . In alternative embodiments, the bearing  60  may be supported by a portion of the hub  50  and may also surround and be supported by a portion of the crankshaft  24  or a portion of another component the damper  32  may be coupled to. 
         [0023]    A case fluid cavity  68  is defined by the case  46  and cover  48 . The ring  62  is a disk shaped member located inside the case fluid cavity  68  and surrounding and in contact with the bearing  60 . The case fluid cavity  68  may include a front chamber  70 , outer chamber  72 , and rear chamber  74 . The front chamber  70  may be defined by a front ring surface  76  and the cover  48 . The outer chamber  72  may be defined by a outer ring surface  78  and the lip portion  58  of the case  46 . The rear chamber  74  may be defined by a rear ring surface  80  and the side portion  56  of the case  46 . 
         [0024]    The ring  62  includes pockets  82  formed in the ring  62  and extending through the front ring surface  76  and defining pocket fluid cavities  84 . In alternative embodiments, the pockets  82  may be located in the rear ring surface  80 . The pockets  82  may also have a wide variety of depths and sizes. In alternative embodiments, the pockets  82  may also be through going, extending through both the front ring surface  76  and rear ring surface  80 . 
         [0025]    The case fluid cavity  68  may be in fluid communication with the pocket fluid cavity  74 . In other embodiments, the pocket fluid cavity  84  may also be fluidly isolated from the case fluid cavity  68 . The pockets  82  may be cylindrical with a circular cross-section, as seen in  FIG. 5 . The pockets  82  may also have other shapes, including oval, square, and rectangular. Also as seen in  FIG. 5 , the pockets  82  may be located symmetrically around the ring  62 . 
         [0026]      FIG. 6  shows that the pockets may also be located at varying distances from the center  88 . One set of pockets  82  is symmetrically distributed along a first perimeter  92  and another set of pockets is symmetrically distributed along a second perimeter  94  located closer to the center  88  than the first perimeter  92 . Additional sets of pockets  82  may be located at varying distance from the center  88 . Locating sets of pockets  82  at varying distances from the center  88  may provide additional tuning of the damper  32  or tuning at multiple orders. In alternative embodiments, the pockets  82  may also be located in asymmetric patterns and at varying distances from the center  88  given proper balancing. 
         [0027]    One mass  64  is located in each pocket fluid cavity  84 . The masses  64  may be cylindrical rods, spheres, blocks, or have another geometric shape that fits within the pocket fluid cavity  84 . The masses  64  may be longer or shorter than the depth of the pockets  82 . 
         [0028]    The masses  64  may be loose in the pockets  82  and independent of the ring  62 . Accordingly, the masses  64  may move freely within the pocket fluid cavity  84  absent an outside force. In alternative embodiments, the motion of the masses  64  may be limited. For example, the pockets  82  may have an oval cross-section and the masses  64  may be sized so that the masses  64  are free to move only in a radial direction. Additional pockets  82  and pocket fluid cavities  84  may also be included without a mass  64 . 
         [0029]    The masses  64  may be the same material as or a different material than the ring  62 , case  46 , or other components. In some embodiments, the masses  64  may be made from a denser material than the ring  62 , case  46 , or other damper  32  components. The damper  32  components may be made from cast iron, forged steel, stainless steel, or other appropriate material for the intended environment and conditions. 
         [0030]    The fluid  66  fills the case fluid cavity  68  and the pocket fluid cavity  84 . The fluid  66  may be a silicon based material or any other material that will retain sufficient viscosity in the given environment or conditions. The fluid  66  may be highly viscous with a viscosity of approximately, roughly, or about 100,000 centistokes to approximately, roughly, or about 1,500,000 centistokes. 
       INDUSTRIAL APPLICABILITY 
       [0031]      FIG. 5  shows the damper  32  with the cover  48  removed for illustrative purposes. The damper  32  is shown spinning in rotation direction  86 . The hub  50  and case  46  are spun by the crankshaft  24 , imparting a force on the fluid  66 . Shearing of the viscous fluid  66  imparts a force on the ring  62 , causing the ring  62  and masses  64  to also spin. As the damper  32  spins or rotates, centrifugal forces push the masses  64  away from a center  88  of the spinning damper  32  and to an outside  90  of the pocket fluid cavity  84 . 
         [0032]    The damper  32  may be suited to accommodate, absorb, or dampen a variety of different sources of energy or motion fluctuations experienced by the crankshaft  24 . The damper  32  may use damping methods including a viscous shearing action to dampen the natural resonance forces of the rotation and a pendulum action to dampen the direct loading forces of vibration. 
         [0033]    The shearing of the viscous fluid  66  may provide a damping effect of the natural resonance forces of the rotation experienced by the crankshaft  24 . As the rotational speed of the crankshaft  24  increases, decreases, accelerates, or decelerates a portion of the mechanical energy generated by the fluctuation or change in speed may be smoothed, absorbed, or dampened. The mechanical energy may be converted to heat as the viscous fluid  66  is sheared in response to the changing speeds of rotation between the case  46  and ring  62 . 
         [0034]    The moving of the masses  64  may also provide a damping effect of the direct loading forces experienced by the crankshaft  24 . Energy is stored in the damper  32  as the centrifugal forces push the masses  64  to the outside  90  of the pocket fluid cavity  84 . As a result, the masses  64  may act as pendulums and move within the pocket fluid cavity  84  in reaction to dynamic loading from a vibration, direct loading, or external force. The viscous fluid  66  may resist the movement of the masses  64 . As a result, the vibration, direct loading, or external forces may be smoothed, absorbed, or dampened. 
         [0035]    While the above description is directed to the damper  32  applied to the crankshaft  24 , it is understood that other applications of the damper  32  exist. The damper  32  may be used with engine camshafts, reciprocating pumps, oil pumps, fuel pumps, rotating shafts, rotating axles, driveshafts, or other rotating components. The damper  32  may be particularly suited in applications with rotational speeds that are below 6,000 revolutions per minute (rpm). The size, weight, of the damper&#39;s  32  components and the viscosity of the fluid  66  may be designed for a wide range of rotation speeds. 
         [0036]    Although the embodiments of this disclosure as described herein may be incorporated without departing from the scope of the following claims, it will be apparent to those skilled in the art that various modifications and variations can be made. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.