Abstract:
A camshaft assembly may include a monolithic camshaft body, a journal member and a thrust ring. The monolithic camshaft body may define lobes and journal regions along an axial extent thereof. The journal member may be separate from and fixed to an axial end of the camshaft body adjacent an end lobe of the camshaft body. The thrust ring may be axially secured to the camshaft assembly at the axial end of the camshaft body.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/244,237, filed on Sep. 21, 2009. The entire disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure relates to engine camshafts, and more specifically to multipiece engine camshaft assemblies. 
       BACKGROUND 
       [0003]    This section provides background information related to the present disclosure which is not necessarily prior art. 
         [0004]    An engine camshaft assembly may include a thrust ring to axially secure the camshaft relative to an engine structure. The thrust rings are typically formed with the camshaft. The camshaft lobes are typically hardened by a process such as induction hardening. The process generally requires an axial spacing between the thrust ring and the adjacent cam lobe. Therefore, additional length may be added to the camshaft to accommodate the required spacing. 
       SUMMARY 
       [0005]    This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
         [0006]    A camshaft assembly may include a monolithic camshaft body, a journal member and a thrust ring. The monolithic camshaft body may define lobes and journal regions along an axial extent thereof. The journal member may be separate from and fixed to an axial end of the camshaft body adjacent an end lobe of the camshaft body. The thrust ring may be axially secured to the camshaft assembly at the axial end of the camshaft body. The journal member may be rotationally supported on an engine structure. 
         [0007]    A method of assembling a camshaft may include forming a monolithic camshaft body including lobes and journal regions along an axial extent thereof. The camshaft lobes may be induction hardened. A journal member and the thrust ring may be secured to an end of the camshaft body after the induction hardening. 
         [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. 
     
    
     
       BRIEF DESCRIPTION OF THE 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 perspective view of a camshaft assembly and a cam phaser according to the present disclosure; 
           [0011]      FIG. 2  is a fragmentary section view of the camshaft assembly shown in  FIG. 1 ; 
           [0012]      FIG. 3  is a fragmentary section view of an alternate camshaft assembly according to the present disclosure; 
           [0013]      FIG. 4  is a fragmentary section view of an alternate camshaft assembly according to the present disclosure; 
           [0014]      FIG. 5  is a fragmentary section view of an alternate camshaft assembly according to the present disclosure; 
           [0015]      FIG. 6  is a fragmentary section view of an alternate camshaft assembly according to the present disclosure; and 
           [0016]      FIG. 7  is a fragmentary section view of an alternate camshaft assembly according to the present disclosure. 
       
    
    
       [0017]    Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
       DETAILED DESCRIPTION 
       [0018]    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. 
         [0019]    With reference to  FIGS. 1 and 2 , a camshaft assembly  10  and a cam phaser  12  are illustrated. The camshaft assembly  10  may include a main portion  14 , a thrust ring  16  and a front journal member  18 . The cam phaser  12  may be coupled to the main portion  14  of the camshaft assembly  10  by a fastener  20 . The cam phaser  12  may include any of a variety of cam phaser assemblies. 
         [0020]    By way of non-limiting example, the cam phaser  12  may include a hydraulically actuated cam phaser having a rotor  21  and a stator  23 . The stator  23  may be rotationally driven by an engine crankshaft. The rotor  21  may be located within the stator  23  and may include radially extending vanes  25  cooperating with the stator  23  to form hydraulic chambers  27  in communication with pressurized fluid, such as oil. The camshaft assembly  10  may be fixed for rotation with the rotor  21  and may be rotated relative to the stator  23  based on the pressurized fluid in the hydraulic chambers  27  acting on the vanes  25 . However, while shown in combination with a cam phaser  12 , it is understood that the present disclosure is not limited to cam phaser applications and applies equally to camshaft assemblies that do not use cam phasers. 
         [0021]    The main portion  14  of the camshaft assembly  10  may define a monolithic camshaft body including lobes  22  integrally formed on a shaft  24 . By way of non-limiting example, the monolithic camshaft body may be a cast part. A first end of the main portion  14  may define an outer radial surface  26  and an axial bore  28 . The outer radial surface  26  may extend axially between an end lobe  22  and the axial end of the main portion  14 . A first axial end surface  30  may be defined between the end lobe  22  and the outer radial surface  26 . The axial bore  28  may include first and second portions  32 ,  34 . The first portion  32  may be engaged with the fastener  20  and the second portion  34  may receive the journal member  18 , as discussed below. 
         [0022]    The thrust ring  16  may be located on the outer radial surface  26  of the main portion  14  and may abut the first axial end surface  30 . The camshaft lobes  22  may be induction hardened before the thrust ring is located on the main portion  14 . Therefore, the axial distance (D 1 ) between the end lobe  22  and the thrust ring  16  may be less than six millimeters, and more specifically less than three millimeters. The reduced distance between the thrust ring  16  and the end lobe  22  may provide for increased axial width of the lobes  22  without increasing the axial length of the camshaft assembly  10 . 
         [0023]    The journal member  18  may include first and second regions  36 ,  38 . The first region  36  may define a bearing journal  40  and the second region  38  may couple the journal member  18  to the main portion  14 . The second region  38  may be pressed into the second portion  34  of the axial bore  28  and frictionally engaged (i.e., interference fit engagement) with the main portion  14 . The first region  36  may have a greater diameter than the second region  38 , defining a second axial end surface  42  therebetween. The first and second axial end surfaces  30 ,  42  may form first and second axial stops. When assembled, the thrust ring  16  may be axially retained between the first and second axial end surfaces  30 ,  42 . 
         [0024]    The camshaft assembly  10  may be part of an engine assembly and may be rotationally supported on an engine structure  44 . The engine structure  44  may define a bearing rotationally supporting the camshaft assembly  10 .  FIG. 2  illustrates the journal member  18  rotationally supported on the engine structure  44 . The camshaft assembly  10  may be axially secured on the engine structure  44  by the cam phaser  12  and the thrust ring  16 . It is understood that the present disclosure applies equally to cam-in-block and overhead camshaft arrangements. The location and assembly of the thrust ring  16  may generally provide for an overall smaller engine length without reducing camshaft lobe width. 
         [0025]    In an alternate arrangement seen in  FIG. 3 , the thrust ring  216  may be located on journal member  218 . The camshaft assembly  210  may be generally similar to the camshaft assembly  10 . However, the thrust ring  216  may be located on an outer radial surface  226  of the second region  238  of the journal member  218 . In another non-limiting example seen in  FIG. 4 , the thrust ring  316  may be integrally formed with the journal member  318  to create monolithic member. 
         [0026]    In an alternate arrangement seen in  FIG. 5 , the camshaft assembly  410  may include a main portion  414  of the camshaft body having an axially extending end portion  438  located within an axially extending bore  434  defined by the journal member  418 . The end portion  438  may be pressed into the bore  434  and frictionally engaged therewith (i.e., interference fit engagement). In another arrangement seen in  FIG. 6 , the camshaft assembly  510  may include the end portion  538  of the camshaft body located within the bore  534  of the journal member  518 . However, in the arrangement of  FIG. 6 , the thrust ring  516  may be located on journal member  518 . In another arrangement seen in  FIG. 7 , the camshaft assembly  610  may include the end portion  638  of the camshaft body located within the bore  634  of the journal member  618 . However, the thrust ring  616  may be integrally formed with the journal member  618  to create monolithic member. 
         [0027]    In any of the camshaft assemblies  10 ,  210 ,  310 ,  410 ,  510 ,  610  discussed above, the camshaft lobes may be induction hardened before the thrust ring  16 ,  216 ,  316 ,  416 ,  516 ,  616  is coupled to the main portion  14 ,  214 ,  314 ,  414 ,  514 ,  614  of the camshaft body. The thrust ring  16 ,  216 ,  316 ,  416 ,  516 ,  616  may then be secured to the camshaft assembly  10 ,  210 ,  310 ,  410 ,  510 ,  610  in any of the arrangements discussed above. Therefore, the spacing typically required between the end lobe and thrust ring may be avoided to provide a shorter overall engine package. 
         [0028]    It is understood that the parts of the camshaft assembly  10  may be coupled to one another in a variety of ways and the present disclosure is not limited to a frictional engagement (i.e., interference fit engagement).