Abstract:
An engine assembly may include an engine structure, a camshaft, a timing wheel and a camshaft position sensor. The camshaft may be rotationally supported within the engine structure and may have a non-magnetic journal rotationally fixed thereto. The timing wheel may be rotationally fixed to the camshaft proximate the non-magnetic journal. The camshaft position sensor may be coupled to the engine structure and configured to determine the rotational position of the camshaft based on a magnetic impulse from the timing wheel.

Description:
FIELD 
       [0001]    The present disclosure relates to engine assemblies, and more specifically to engine camshaft assemblies having timing wheels. 
       BACKGROUND 
       [0002]    This section provides background information related to the present disclosure which is not necessarily prior art. 
         [0003]    Internal combustion engines include one or more camshafts for actuation of intake and exhaust valves. Engines may additionally include a cam phaser to adjust valve timing. Engines including cam phasers may include timing wheels to determine the rotational position of the camshaft during operation. The timing wheels may have a magnetic permeability that is determined by a sensor to determine rotational position of the camshaft. However, the timing wheel may require axial spacing from the camshaft journals to prevent magnetic journals from affecting the position reading by the sensor. 
       SUMMARY 
       [0004]    An engine assembly may include an engine structure, a camshaft, a timing wheel and a camshaft position sensor. The camshaft may be rotationally supported within the engine structure and may have a non-magnetic journal rotationally fixed thereto. The timing wheel may be rotationally fixed to the camshaft proximate the non-magnetic journal. The camshaft position sensor may be coupled to the engine structure and configured to determine the rotational position of the camshaft based on a magnetic impulse from the timing wheel. 
         [0005]    A camshaft assembly may include a first shaft, a non-magnetic journal and a magnetic timing wheel. The non-magnetic journal may be rotationally fixed to the first shaft. The magnetic timing wheel may be located on the first shaft proximate the non-magnetic journal. 
         [0006]    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 
         [0007]    The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present disclosure in any way. 
           [0008]      FIG. 1  is schematic illustration of an engine assembly according to the present disclosure; and 
           [0009]      FIG. 2  is an illustration of the camshaft assembly shown in  FIG. 1 . 
       
    
    
       [0010]    Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
       DETAILED DESCRIPTION 
       [0011]    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. 
         [0012]    With reference to  FIG. 1 , an engine assembly  10  is illustrated. The engine assembly  10  may include a cam-in-block design having a V-configuration. While a cam-in-block design is illustrated, it is understood that the present disclosure additionally applies to various other engine configurations including, but not limited to, overhead cam engines. The engine assembly  10  may include an engine structure  12  defining cylinders  14 , pistons  16  disposed within the cylinders  14 , a crankshaft  18 , connecting rods  20  coupling the pistons  16  to the crankshaft  18 , and a valvetrain assembly  22 . The engine structure  12  may include an engine block  24  and cylinder heads  26 . 
         [0013]    The engine block  24  may define first and second banks  28 ,  30  of cylinders  14  disposed at an angle relative to one another. The cylinder heads  26  may be mounted to the engine block  24  above the cylinders  14 . While  FIG. 1  illustrates the first and second banks  28 ,  30  disposed at an angle relative to one another, it is understood that the present disclosure is not limited to engines having a V-configuration. 
         [0014]    The valvetrain assembly  22  may include a cam phaser  32 , intake and exhaust valves  34 ,  36 , a valve actuation assembly  38 , a camshaft  40 , and a camshaft position sensor  42 . The valve actuation assembly  38  may include intake and exhaust rocker arm assemblies  44 ,  46  and valve lift mechanisms  48 . Each of the intake rocker arm assemblies  44  may be engaged with an intake valve  34  and may be coupled to the engine structure  12 , and more specifically may be coupled to the cylinder head  26 . A first end of the intake rocker arm assembly  44  may be engaged with the intake valve  34  and a second end may be engaged with a first end of the valve lift mechanism  48 . 
         [0015]    Each of the exhaust rocker arm assemblies  46  may be engaged with an exhaust valve  36  and may be coupled to the engine structure  12 , and more specifically may be coupled to the cylinder head  26 . A first end of the exhaust rocker arm assembly  46  may be engaged with the exhaust valve  36  and a second end may be engaged with a first end of the valve lift mechanism  48 . The valve lift mechanism  48  may include a pushrod  50  and a lifter  52 . 
         [0016]    With additional reference to  FIG. 2 , the camshaft  40  may include first and second sets of lobes  54 ,  56 , a first shaft  58 , a second shaft (not shown), a first journal  60 , second journals  62 , and a timing wheel  64 . The second shaft may be located within the first shaft  58  and rotatable relative thereto. The first shaft  58  and the second shaft may each be coupled to the cam phaser  32  and may be rotated relative to one another. The first set of lobes  54  may be rotationally fixed to the first shaft  58  and the second set of lobes  56  may be rotationally fixed to the second shaft. By way of non-limiting example, the first set of lobes  54  may include intake lobes and the second set of lobes  56  may include exhaust lobes. Alternatively, the first set of lobes  54  may include exhaust lobes and the second set of lobes  56  may include intake lobes. The present disclosure additionally applies to camshafts including only intake or exhaust lobes (i.e., dual overhead camshaft arrangements). 
         [0017]    The first journal  60  and second journals  62  may be rotationally fixed to the first shaft  58 . The first journal  60  may be located at a first end of the camshaft  40  adjacent the cam phaser  32 . The second journals  62  may be located along the first shaft  58  between the first journal  60  and a second end of the camshaft  40  opposite the first end. First and second lobes  54 ,  56  may be located between the first journal  60  and an adjacent second journal  62 , as well as between adjacent pairs of second journals  62 . 
         [0018]    The timing wheel  64  may be located axially between the first and second journals  60 ,  62 . By way of non-limiting example, the timing wheel may be located within 6 millimeters (mm) of the first journal  60 . More specifically, the timing wheel  64  may abut an axial end face of the first journal  60 . The timing wheel  64  may include recesses  66 . The timing wheel  64  may have a magnetic permeability that is sensed by the camshaft position sensor  42 . The magnetic permeability of the timing wheel  64  varies at the recesses  66 , providing for determination of the rotational orientation of the camshaft  40  by the camshaft position sensor  42  during engine operation. 
         [0019]    In order to accommodate the positioning of the timing wheel  64  on the camshaft  40 , the first journal  60  may be non-magnetic. By way of non-limiting example, the first journal  60  may be formed from a non-magnetic material such as austenitic manganese steel (i.e., Hadfield steel). Alternatively, the first journal  60  may be formed from other steels and demagnetized after machining of the journal is completed. Providing the first journal  60  free from magnetic charge allows the placement of the timing wheel  64  discussed above while preventing the first journal  60  from influencing the magnetic impulses sensed by the camshaft position sensor  42 .