Patent Publication Number: US-8109246-B2

Title: Camshaft damping mechanism and method of assembly

Description:
FIELD 
     The present disclosure relates to mechanisms for damping camshaft vibration. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     Engine assemblies may include a damping mechanism engaged with one or more camshafts to damp a vibrations resulting from a load applied to the camshaft(s) by a drive mechanism, such as a chain drive or a belt drive. These damping mechanisms generally require assembly to the engine block for a cam-in-block engine or to the cylinder head for an overhead cam engine configuration. The additional assembly typically required may result in greater assembly time and expense in assembling an engine. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not comprehensive of its full scope or all of its features. 
     A camshaft damping mechanism may include first and second housing members and a biasing member. The first housing member may be engaged with a camshaft. The second housing member may be slidably coupled to the first housing member and may abut an engine structure. The biasing member may be retained axially between the first and second housing members and may force the first housing member in an outward axial direction from the second housing member. 
     A method of assembling an engine may include assembling a camshaft damping mechanism including a first housing member, a second housing member slidably coupled to the first housing member, and a biasing member retained axially between the first and second housing members and forcing the first housing member in an outward axial direction from the second housing member. The method may further include locating the camshaft damping mechanism on an engine structure. The second housing member may abut the engine structure after the locating. The camshaft may be secured to the engine structure and may overly and abut the first housing member of the camshaft damping mechanism to secure the camshaft damping mechanism between the camshaft and the engine structure. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present disclosure in any way. 
         FIG. 1  is plan view of a portion of an engine assembly according to the present disclosure; 
         FIG. 2  is a plan view of a cylinder head and camshaft damping mechanisms of the engine assembly of  FIG. 1 ; 
         FIG. 3  is a perspective view of the camshaft damping mechanism of  FIG. 2 ; 
         FIG. 4  is a perspective exploded view of the camshaft damping mechanism of  FIG. 2 ; 
         FIG. 5  is a section view of the camshaft damping mechanism of  FIG. 2 ; and 
         FIG. 6  is a perspective exploded view of an alternate camshaft damping mechanism according to the present disclosure. 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     Examples of the present disclosure will now be described more fully with reference to the accompanying drawings. The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
     Referring now to  FIGS. 1 and 2 , a portion of an engine assembly  10  is illustrated. The engine assembly  10  may include a cylinder head  12 , intake and exhaust camshafts  14 ,  16 , a camshaft drive assembly  18 , and camshaft damping mechanisms  20 . The cylinder head  12  may generally define an engine structure supporting the intake and exhaust camshafts  14 ,  16  and the camshaft damping mechanisms  20 . The cylinder head  12  may define first and second recesses  22 ,  24  housing the camshaft damping mechanisms  20  therein. 
     While the camshaft damping mechanisms  20  are illustrated in combination with a cylinder head of a dual overhead camshaft engine, it is understood that the present teachings are not limited to such a configuration. By way of non-limiting example, the camshaft damping mechanisms  20  may be incorporated into single overhead camshaft engine configurations, as well as cam-in-block engine configurations. In a cam-in-block configuration, the first and second recesses  22 ,  24  defined in the cylinder head  12  of the present disclosure may be located within an engine block (not shown). Further, it is understood that the present teachings may be incorporated into engine configurations including, but not limited to, in-line engines and V-engines. 
     The camshaft drive assembly  18  may include intake and exhaust cam phasers  26 ,  28  and a drive member  30 . The drive member  30  may be in a variety of forms including, but not limited to, a drive chain or a drive belt. The intake cam phaser  26  may be coupled to the intake camshaft  14  and the exhaust cam phaser  28  may be coupled to the exhaust camshaft  16 . The intake cam phaser  26  may include a first drive sprocket  32  and the exhaust cam phaser  28  may include a second drive sprocket  34 . The first and second drive sprockets  32 ,  34  may each be engaged with and rotatably driven by the drive member  30 . The drive member  30  may be driven by a rotating member such as a crankshaft (not shown). The camshaft damping mechanisms  20  may reduce vibration of the intake and exhaust camshafts  14 ,  16  resulting from loads imparted on the intake and exhaust camshafts  14 , 16  from the camshaft drive assembly  18 . 
     Referring now to  FIGS. 3-5 , the camshaft damping mechanism  20  may include a first housing member  36 , a second housing member  38 , and a biasing member  40 . The first housing member  36  may include an axially extending body having first and second portions  42 ,  44 . The first portion  42  may include a roller member  46  on a first side thereof and may define a first seating surface  48  on a second side thereof generally opposite the first side. The roller member  46  on one of the camshaft damping mechanisms  20  may engage the intake camshaft  14  and the roller member  46  on the other camshaft damping mechanism  20  may engage the exhaust camshaft  16 . The second portion  44  may include a first annular wall  50  extending axially from the first seating surface  48  and defining a first cavity  52 . The second portion  44  may additionally include a first retention mechanism  54 . The first retention mechanism  54  may include first and second pins  56 ,  58  extending radially inward from and axially fixed to the first annular wall  50 . The first and second pins  56 ,  58  may be spaced approximately one hundred and eighty degrees from one another. 
     The second housing member  38  may include an axially extending body having first and second portions  60 ,  62 . The first portion  60  may define a second seating surface  64  and the second portion  62  may include a second annular wall  66  extending axially from the second seating surface  64  and defining a second cavity  68 . The second seating surface  64  may include an aperture  70  defining an oil drain hole. The aperture  70  may define a series of flats  72  for engagement with a tool (not shown) to rotationally fix the second housing member  38  during assembly of the camshaft damping mechanism  20 . The second portion  62  may additionally include a second retention mechanism  74 . 
     The second retention mechanism  74  may include first and second axial slots  76 ,  78  extending along the second annular wall  66  and first and second axial recesses  80  (one of which is shown) extending along the second annular wall  66  directly adjacent the first and second axial slots  76 ,  78 . The first and second axial slots  76 ,  78  may extend radially through the second annular wall  66  and may each be located axially inward from an end of the second annular wall  66  adjacent the first housing member  36 . The first and second axial recesses  80  may extend radially into the second annular wall  66  a distance less than the thickness of the second annular wall  66  and may extend axially through the end  84  of the second annular wall  66 . 
     The first annular wall  50  may be slidably disposed within the second annular wall  66  and axially secured thereto through an engagement between the first and second retention mechanisms  54 ,  74 . More specifically, the first and second pins  56 ,  58  may be located within the first and second axial slots  76 ,  78 . The biasing member  40  may be retained axially between the first and second housing members  36 ,  38  between the first and second seating surfaces  48 ,  64 . The biasing member  40  may be housed within the first and second cavities  52 ,  68  and may generally urge the first and second housing members  36 ,  38  axially outward relative to one another. By way of non-limiting example, the biasing member  40  may include a compression spring. 
     The engagement between the first and second pins  56 ,  58  and the first and second axial slots  76 ,  78  may provide guided axial displacement between the first and second housing members  36 ,  38  while axially securing the first and second housing members  36 ,  38  to one another. During engine operation, and by way of non-limiting example, the second housing member  38  may be axially fixed relative to the cylinder head  12  and the first housing member  36  may be axially displaceable relative to the second housing member  38  and the cylinder head  12 . The first housing member  36  of a first camshaft damping mechanism  20  may be displaced between first and second axial positions based on engagement with a lobe member  86  (seen in  FIG. 1 ) of the intake camshaft  14  and a second camshaft damping mechanism  20  may be displaced between first and second axial positions based on engagement with a lobe member  88  (seen in  FIG. 1 ) of the exhaust camshaft  16 . 
     The camshaft damping mechanisms  20  may be assembled before being located in the cylinder head  12 . During assembly, the biasing member  40  may be located within the second cavity  68  of the second housing member  38 . The first and second pins  56 ,  58  on the first housing member  36  may then be rotationally aligned with the first and second axial recesses  80 . Next, the first housing member  36  may be advanced axially relative to the second housing member  38 . As the first housing member  36  is advanced axially toward the second housing member  38 , the first and second pins  56 ,  58  advance axially along the first and second axial recesses  80  and the biasing member  40  is compressed. 
     Once the first and second pins  56 ,  58  are axially aligned with the first and second axial slots  76 ,  78 , the first housing member  36  may be rotated relative to the second housing member  38  in a rotational direction from the first and second axial recesses  80  toward the first and second axial slots  76 ,  78 . After the first and second pins  56 ,  58  are located within the first and second axial slots  76 ,  78 , the axial force applied to the first housing member  36  to axially advance the first housing member  36  may be removed and the biasing member  40  may urge the first housing member  36  axially outward from the second housing member  38  and may bias the first and second pins  56 ,  58  against ends  90 ,  92  of the first and second axial slots  74 ,  76 , securing the first housing member  36 , the second housing member  38 , and the biasing member  40  to one another as an unitary member. 
     Once assembled, the camshaft damping mechanisms  20  may be located in the recesses  22 ,  24  in the cylinder head  12 . After the camshaft damping mechanisms  20  have been located in the recesses  22 ,  24 , the intake and exhaust camshafts  14 ,  16  may be secured to the cylinder head  12 . The first camshaft damping mechanism  20  may be secured between the intake camshaft  14  and the cylinder head  12  and the second camshaft damping mechanism  20  may be secured between the exhaust camshaft  16  and the cylinder head  12 , eliminating the need for additional fasteners and assembly processes to secure the camshaft damping mechanisms  20  to the cylinder head  12 . 
     An alternate camshaft damping mechanism  120  is illustrated in  FIG. 6 . The camshaft damping mechanism  120  may be generally similar to the camshaft damping mechanism  20 . Therefore, it is understood that the description of the camshaft damping mechanism  20  applies equally to the camshaft damping mechanism  120  with the exceptions indicated below. The first retention mechanism  154  of the first housing member  136  may include first and second axial slots  176  (one of which is shown) located in the first annular wall  150 . The second retention mechanism  174  of the second housing member  138  may include first and second pins  156  (one of which is shown) extending radially inward from the second annular wall  166 . The second annular wall  166  may be slidably disposed within the first annular wall  150  and the first and second pins  156  may be slidably disposed within the first and second axial slots  176  to guide axial displacement between the first and second housing members  136 ,  138  and axially secure the first and second housing members  136 ,  138  to one another. 
     It is understood that the description of the engagement between the first and second housing members  36 ,  38  and the first and second housing members  136 ,  138  is merely exemplary in nature and that the present teachings are in no way limited to the configurations described above.