Abstract:
A method of assembling a camshaft may include locating a first lobe member of the camshaft on a first shaft and inserting a locking pin into a first bore in the first lobe member and into a second bore in the first shaft. The locking pin may include a first recess extending into a first end thereof defining a first annular wall. A first retaining member may be forced into a first recess. The forcing may displace the annular wall in an outward radial direction and into a frictional engagement with the first bore.

Description:
FIELD 
       [0001]    The present disclosure relates to engine camshaft assemblies. 
       BACKGROUND 
       [0002]    This section provides background information related to the present disclosure which is not necessarily prior art. 
         [0003]    Engines typically include a camshaft to actuate intake and exhaust valves. Some camshafts are concentric camshafts that provide for relative rotation between, for example, the intake and exhaust lobes. The intake lobes may be fixed to an outer shaft for rotation with the shaft and the exhaust lobes may be rotatably supported on the shaft. Alternatively, the exhaust lobes may be fixed to the outer shaft for rotation with the shaft and the intake lobes may be rotatably supported on the shaft. In any arrangement, the lobes that are rotatably supported on the outer shaft may be rotationally fixed to the inner shaft using a fastener. Insertion of these fasteners may apply a radial load to the camshaft during assembly. 
       SUMMARY 
       [0004]    This section provides a general summary of the disclosure, and is not comprehensive of its full scope or all of its features. 
         [0005]    A method of assembling a camshaft may include locating a first lobe member of the camshaft on a first shaft and inserting a locking pin into a first bore in the first lobe member and into a second bore in the first shaft. The locking pin may include a first recess extending into a first end thereof defining a first annular wall. A first retaining member may be forced into the first recess. The forcing may displace the annular wall in an outward radial direction and into a frictional engagement with the first bore. 
         [0006]    The method may further include forcing a second retaining member into a second recess located in a second end of the locking pin generally opposite the first end. The first retaining member may be forced into the first recess simultaneously with the second retaining member being forced into the second recess. 
         [0007]    The camshaft assembly may include a first shaft including a first radial bore, a first lobe member located on the first shaft and including a second radial bore aligned with the first radial bore, and a locking pin located within the first and second radial bores. The locking pin may include first and second longitudinal ends generally opposite one another. The first longitudinal end may include a first recess extending axially therein and a first retaining member located within the first recess. The first retaining member may bias an annular wall defined by the first recess in an outward radial direction into a frictional engagement with a first portion of the second radial bore. 
         [0008]    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 
         [0009]    The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present disclosure in any way. 
           [0010]      FIG. 1  is a schematic illustration of an engine assembly according to the present disclosure; 
           [0011]      FIG. 2  is a perspective view of the camshaft and cam phaser of  FIG. 1 ; 
           [0012]      FIG. 3  is a perspective exploded view of the camshaft of  FIG. 1 ; 
           [0013]      FIG. 4  is a fragmentary section view of a camshaft and a tool assembly according to the present disclosure; and 
           [0014]      FIG. 5  is a fragmentary section view of the camshaft according to the present disclosure. 
       
    
    
       [0015]    Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
       DETAILED DESCRIPTION 
       [0016]    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. 
         [0017]    Referring now to  FIG. 1 , an exemplary engine assembly  10  is schematically illustrated. The engine assembly  10  may include an engine  12  including a plurality of cylinders  14  having pistons  16  disposed therein. The engine  12  may further include an intake valve  18 , an exhaust valve  20 , and intake and exhaust valve lift mechanisms  22 ,  24  for each cylinder  14 , as well as a camshaft  26  and a cam phaser  28 . 
         [0018]    The intake valve lift mechanism  22  may include a pushrod  30  and a rocker arm  32 . The exhaust valve lift mechanism  24  may additionally include a pushrod  30  and a rocker arm  32 . Pushrods  30  may be engaged with the camshaft  26  to actuate the rocker arms  32  and selectively open the intake and exhaust valves  18 ,  20 . While the engine assembly  10  is illustrated as a pushrod engine, it is understood that the present disclosure is not limited to pushrod engines and may be applicable to a variety of other engine configurations as well, such as overhead cam engines. 
         [0019]    With reference to  FIGS. 2-5 , the camshaft  26  may include first and second shafts  34 ,  36 , a first set of lobe members  38 ,  40 ,  42 ,  44 ,  46 , a second set of lobe members  48 ,  50 ,  52 ,  54 , and fasteners  56 . In the present example, the first set of lobe members  38 ,  40 ,  42 ,  44 ,  46  may form an intake lobe set and the second set of lobe members  48 ,  50 ,  52 ,  54  may form an exhaust lobe set. However, it is understood that alternate arrangements may be provided where the first set of lobe members  38 ,  40 ,  42 ,  44 ,  46  may form an exhaust lobe set and the second set of lobe members  48 ,  50 ,  52 ,  54  may form an intake lobe set. Further, each of the first and second sets of lobe members  38 ,  40 ,  42 ,  44 ,  46 ,  48 ,  50 ,  52 ,  54  are not limited to only intake or exhaust valves. For example, the first and second sets of lobe members  38 ,  40 ,  42 ,  44 ,  46 ,  48 ,  50 ,  52 ,  54  may each include an intake lobe and/or an exhaust lobe. The first shaft  34  may be fixed for rotation with a first phaser member  58  and the second shaft  36  may be fixed for rotation with a second phaser member  60 . The first and second phaser members  58 ,  60  may be rotatable relative to one another and relative to a rotationally driven member  62  of the phaser  28 . 
         [0020]    The first shaft  34  may include an annular wall  64  defining an inner bore  66 . The second shaft  36  may be rotatably disposed within the inner bore  66  of the first shaft  34 . The first shaft  34  may include slots  68  (seen in  FIGS. 4 and 5 ) therethrough and the second shaft  36  may include apertures  70  that receive the fasteners  56  therein and couple the second set of lobe members  48 ,  50 ,  52 ,  54  for rotation with the second shaft  36 . The slots  68  may form radial bores through the first shaft  34  and the apertures  70  may form radial bores through the second shaft  36 . The slots  68  in the first shaft  34  may generally allow for a rotational travel of the fasteners  56  therein. 
         [0021]    The first set of lobe members  38 ,  40 ,  42 ,  44 ,  46  may be fixed for rotation with the first shaft  34 . The engagement between the first set of lobe members  38 ,  40 ,  42 ,  44 ,  46  and the first shaft  34  may include a friction fit engagement. The second set of lobe members  48 ,  50 ,  52 ,  54  may be disposed between adjacent ones of the first set of lobe members  38 ,  40 ,  42 ,  44 ,  46 . The second set of lobe members  48 ,  50 ,  52 ,  54  may be rotatably disposed on the first shaft  34  and fixed for rotation with the second shaft  36  by the fasteners  56 . 
         [0022]    As seen in  FIGS. 4 and 5 , the fasteners  56  may each include a locking pin  72  and first and second retaining members  74 ,  76 . The locking pin  72  may include a first end  78  having a first recess  80  and a second end  82  generally opposite the first end  78  having a second recess  84 . The first and second recesses  80 ,  84  may extend axially toward one another and may be separated by a generally solid medial portion  86  of the locking pin  72 . The first recess  80  may define a first annular wall  88  at the first end  78  and the second recess  84  may define a second annular wall  90  at the second end  82 . 
         [0023]    The first retaining member  74  may be located in the first recess  80  and the second retaining member  76  may be located in the second recess  84 . The first and second retaining members  74 ,  76  may fix the locking pin  72  to one of the lobe members  48 ,  50 ,  52 ,  54 . By way of non-limiting example, each of the first and second retaining members  74 ,  76  may be in the form of a generally spherical member. 
         [0024]    First and second tools  92 ,  94  may be used to fix the first and second retaining members  74 ,  76  within the first and second recesses  80 ,  84 . The locking pin  72  may have an outer diameter (D L ) that is less than the diameter (D C ) of the bore  96  extending through the lobe member  48 , less than the width (D S1 ) of the slot  68  in the first shaft  34 , and less than the diameter (D S2 ) of the aperture  70  in the second shaft  36 . Therefore, the locking pin  72  may be placed within the bore  96 , the slot  68 , and the aperture  70  with little frictional resistance. 
         [0025]    The first tool  92  may force the first retaining member  74  in a first axial direction (Al) into the first recess  80 . An end of the first recess  78  may form an axial end stop for the first retaining member  74 . As seen in  FIG. 4 , the first recess  80  may have an initial diameter (D 1i ) that is less than the diameter (D R1 ) of the first retaining member  74 . Therefore, when the first retaining member  74  is forced into the first recess  80 , the first annular wall  88  is deformed in an outward radial direction and into a frictional engagement with a first portion of the bore  96  in the lobe member  48 , as seen in  FIG. 5 . The first annular wall  88  may be deformed to a final outer diameter (D Lf ) that is greater than the outer diameter (D L ) of the remainder of the locking pin  72  in order to provide the frictional engagement with the lobe member  48 . The first retaining member  74  may be retained within the first recess  84  after being forced into the first recess  74  by the first tool  92 . 
         [0026]    Similarly, the second tool  94  may force the second retaining member  76  into the second recess  84 . It is understood that the relationship between the second retaining member  76  and the second recess  84  may be generally similar to the first retaining member  74  and the first recess  78  described above. However, the second retaining member  76  may be displaced in a second axial direction (A 2 ) generally opposite the first axial direction (A 1 ). 
         [0027]    The frictional engagement created by the displacement of the first and second retaining members  74 ,  76  may generate forces on the camshaft  26  during assembly. More specifically, the installation of the first retaining member  74  may generate a first force (F 1 ) in the first axial direction (A 1 ) and the installation of the second retaining member  76  may generate a second force (F 2 ) in the second axial direction (A 2 ). The first and second forces (F 1 , F 2 ) may be applied in axial directions (A 1 , A 2 ) relative to the locking pin  72  and in radial directions relative to the first and second shafts  34 ,  36 . Further, the first and second forces (F 1 , F 2 ) may be equal to one another in opposite directions, producing a net force of approximately zero. Therefore, the first and second retaining members  74 ,  76  may be installed in the locking pin  72  simultaneously to reduce a bending force applied to the first and second shafts  34 ,  36 . 
         [0028]    It is understood that the fastener  56  is shown in combination with the lobe member  48  in  FIGS. 4 and 5  for simplicity and the description applies equally to the remainder of the second set of lobe members  50 ,  52 ,  54 .