Abstract:
A camshaft phaser, including: an inner rotor with radially outwardly extending vanes which is connected to the inner camshaft; a stator having radially inwardly directed projections which contact the outer surface of the rotor and form working spaces into which the vanes extend, the vanes divide the working spaces into first and second sets of pressure chambers which can be pressurized with a hydraulic medium in order to rotate the rotor in an advancing or retarding direction; a front cover connected to a front side of the assembly defining a front side of the pressure chambers; and a rear cover connected to the rear side of the assembly defining a rear side of the pressure chambers, having first and second protrusions directed toward and meshed with complementary first and second indentations on an outer camshaft.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure relates to a camshaft phaser or adjuster for the inner camshaft of a concentric camshaft assembly, and in particular to a camshaft phaser or adjuster for adjusting the relative rotational angle position of an inner camshaft of a concentric camshaft assembly relative to the phase position of the outer camshaft and the crankshaft of an internal combustion engine. 
       BACKGROUND 
       [0002]    Camshaft phasers that operate according to the vane-cell principle for use on single camshafts are known. These are described in publications by the assignee of the present invention, including U.S. Pat. No. 6,805,080, which is incorporated herein by reference as if fully set forth. These work well in connection with DOHC engines where all the intake or exhaust cam lobes are located on separately located intake and exhaust camshafts. 
         [0003]    It has also been known to use camshaft phasers in connection with concentric camshaft assemblies for controlling the phase position of the inner camshaft, the outer camshaft or both. One such arrangement is described in DE 10 2006 024 793 A1. This publication discloses a dual phasing system for a concentric camshaft assembly which includes two camshaft phasers which are located at the front of an engine that are axially spaced adjacent to one another. These two camshaft phasers allow independent control of the rotation angle of the outer and inner co-axial camshafts relative to the crankshaft in order to allow separate adjustment of the timing of the intake and the exhaust valves of the internal combustion engine. However, this arrangement provides additional complexity which is often not required to obtain many of the benefits of adjusting either the inner or the outer camshafts of a concentric camshaft assembly without the need for adjusting both. 
         [0004]    It would be desirable to provide a camshaft phaser for a concentric camshaft assembly that allows for phasing of either the intake or exhaust lobes of a camshaft in which the drive load from the timing chain or belt extending from the crankshaft to the timing gear or timing belt pulley of the concentric camshaft arrangement is transmitted to the outer shaft of the concentric camshaft. 
       SUMMARY 
       [0005]    According to aspects illustrated herein, there is provided a camshaft phaser, including: 
         [0000]    an inner rotor with radially outwardly extending vanes which is connected to the inner camshaft; a stator having radially inwardly directed projections which contact the outer surface of the rotor and form working spaces into which the vanes extend, the vanes divide the working spaces into first and second sets of pressure chambers which can be pressurized with a hydraulic medium in order to rotate the rotor in an advancing or retarding direction; a front cover connected to a front side of the assembly defining a front side of the pressure chambers; and a rear cover connected to the rear side of the assembly defining a rear side of the pressure chambers, having first and second protrusions directed toward and meshing with complementary first and second indentations on an outer camshaft. 
         [0006]    According to further aspects illustrated herein, the first and second protrusions are different widths. According to yet further aspects illustrated herein, the first, second and third protrusions are separated by different circumferential distances and mesh with first, second and third indentations in an outer camshaft. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    Various embodiments are disclosed, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, in which: 
           [0008]      FIG. 1  is a perspective view of a cylindrical coordinate system demonstrating spatial terminology used in the present application; 
           [0009]      FIG. 2  is a side view of a camshaft phaser and concentric camshaft according to one example embodiment; 
           [0010]      FIG. 3  is a cross-sectional view of the camshaft phaser and concentric camshaft of  FIG. 2  taken along line A-A; 
           [0011]      FIG. 4  is a front perspective view of the rear cover and outer camshaft of  FIG. 2 ; 
           [0012]      FIG. 5  is a rear perspective view of the rear cover and outer camshaft of  FIG. 2 ; 
           [0013]      FIG. 6  is a cross sectional view of the camshaft phaser of  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    At the outset, it should be appreciated that like drawing numbers on different drawing views identify identical, or functionally similar, structural elements of the disclosure. It is to be understood that the disclosure as claimed is not limited to the disclosed aspects. 
         [0015]    Furthermore, it is understood that this disclosure is not limited to the particular methodology, materials and modifications described and as such may, of course, vary. It is also understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to limit the scope of the present disclosure. 
         [0016]    Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs. It should be understood that any methods, devices or materials similar or equivalent to those described herein can be used in the practice or testing of the disclosure. 
         [0017]      FIG. 1  is a perspective view of cylindrical coordinate system  10  demonstrating spatial terminology used in the present application. The present application is at least partially described within the context of a cylindrical coordinate system. System  10  includes longitudinal axis  11 , used as the reference for the directional and spatial terms that follow. Axial direction AD is parallel to axis  11 . Radial direction RD is orthogonal to axis  11 . Circumferential direction CD is defined by an endpoint of radius R (orthogonal to axis  11 ) rotated about axis  11 . 
         [0018]    To clarify the spatial terminology, objects  12 ,  13 , and  14  are used. An axial surface, such as surface  15  of object  12 , is formed by a plane co-planar with axis  11 . Axis  11  passes through planar surface  15 ; however any planar surface co-planar with axis  11  is an axial surface. A radial surface, such as surface  16  of object  13 , is formed by a plane orthogonal to axis  11  and co-planar with a radius, for example, radius  17 . Radius  17  passes through planar surface  16 ; however any planar surface co-planar with radius  17  is a radial surface. Surface  18  of object  14  forms a circumferential, or cylindrical, surface. For example, circumference  19  passes through surface  18 . As a further example, axial movement is parallel to axis  11 , radial movement is orthogonal to axis  11 , and circumferential movement is parallel to circumference  19 . Rotational movement is with respect to axis  11 . The adverbs “axially,” “radially,” and “circumferentially” refer to orientations parallel to axis  11 , radius  17 , and circumference  19 , respectively. For example, an axially disposed surface or edge extends in direction AD, a radially disposed surface or edge extends in direction R, and a circumferentially disposed surface or edge extends in direction CD. 
         [0019]      FIG. 2  is a side view of a camshaft phaser assembly  1  and concentric camshaft assembly  2  according to one example embodiment.  FIG. 3  is a cross-sectional view of camshaft phaser assembly  1  and concentric camshaft assembly  2  of  FIG. 2  taken along line A-A.  FIG. 4  is a front perspective view of rear cover  10  and outer camshaft  20  of  FIG. 2 .  FIG. 5  is a rear perspective view of rear cover  10  and outer camshaft  20  of  FIG. 2 .  FIG. 6  is a cross sectional view of camshaft phaser assembly  1  of  FIG. 2 . The following description should be viewed in light of  FIGS. 2-6 . 
         [0020]    Camshaft phaser assembly  1  for concentric camshaft assembly  2  is shown. The concentric camshaft assembly  2 , which is shown in most detail in  FIG. 3 , includes the inner camshaft  21  having a front end  22 , with a central bolt receiving hole  16  oil feed passages  18 . Outer camshaft  20 , concentric with inner camshaft  21  is shown as having a first or front end  23  and a second end or main body  24 , however, it will be understood by one skilled in the art that first end  23  and second end  24  may be formed as one component. Those skilled in the art will understand that both the inner and outer camshafts include cam lobes, with the cam lobes of the inner camshaft protruding through openings in the outer tubular camshaft. One of the inner camshaft or the outer camshaft is used to control the opening of the intake valves of an internal combustion engine, and the other is used to control the opening of the exhaust valves. 
         [0021]    Camshaft phaser assembly  1  adjusts the relative rotational position of inner camshaft  21  relative to outer camshaft  20  and a crankshaft (not shown) of an internal combustion engine (not shown). As shown in detail in  FIGS. 3 and 6 , the camshaft phaser  1  includes rotor  40  having radially outwardly directed vanes  41 . The rotor  30  is located radially inside stator  50  which includes radially inwardly directed projections  51 . These projections  51  include bearing surfaces  52  which slidingly engage the outer surface of the rotor  40  at positions between the vanes  41 . The vanes  41  extend into working spaces  42  defined between the projections  51  to divide the working spaces  42  into a first set of chambers  44  and a second set of chambers  46 . The front and rear walls of these chambers are defined by a front cover  60  and a rear cover  10 . The front and rear covers  60 ,  10  are connected to the stator  50  via bolts  55 . Timing or drive gear  30  is connected to, for example by press fit, an outer radial surface of outer camshaft first end  23 . Torque and rotational motion is transferred from the crankshaft (not shown) of the associated internal combustion engine (not shown) to timing gear  30  using a chain, to outer camshaft first end  23 , into camshaft phaser assembly  1  and ultimately into inner camshaft  21 . Alternatively, instead of a timing gear  30 , a timing belt pulley could also be provided or any other suitable drive could be utilized for transferring the rotating motion of the crankshaft to the camshaft phaser  1 . The timing gear  30  could alternatively be formed on or connected to the front or rear covers  60 ,  10  or to stator  50 . 
         [0022]    Camshaft phaser assembly  1  is oriented on concentric camshaft assembly  2  and torque and rotational movement are transferred between outer camshaft  20  and camshaft phaser assembly  1  by mating or meshing projections  11  on rear cover  10  with indentations  61  in outer camshaft  20 . One of ordinary skill in the art will understand that projections in outer camshaft  20  can also mesh with indentations in rear cover  10 . More specifically, rear cover  10  includes first protrusion  11 A with first width  200  extending in a first axial direction separated from second protrusion  11 B with second width  201  extending in the first axial direction. First protrusion  11 A and second protrusion  11 B are separated by a first circumferential distance x. Circumferential distances are defined as the distance between adjacent axially extending end walls of adjacent protrusions. Third protrusion  11 C with third width  202  extending in the first axial direction is separated from the second protrusion  11 B by a second circumferential distance y. In a first embodiment first width  200 , second width  201  and third width  202  are different. In a second embodiment, first circumferential distance x and second circumferential distance y are different. In a third embodiment, first width  200 , second width  201  and third width  202  are different and first circumferential distance x and second circumferential distance y are different. As shown in  FIGS. 4 and 5 , second protrusion  11 B is a group of protrusions separated by equal circumferential distances. Any number of protrusions within such a group of protrusions are contemplated by this disclosure, as possible within particular applications and geometric restrictions. Furthermore, multiple further sets of protrusions are contemplated, as shown for example in  FIGS. 4 and 5 , fourth protrusion  11 D, fifth protrusion  11 E and sixth protrusion  11 F. 
         [0023]    Protrusions  11  align and mesh with indentations  61  of outer camshaft  20  in only one specific orientation. In the embodiment shown, for example, first protrusion  11 A aligns and meshes with indentation  61 A and second protrusion  11 B aligns and meshes with indentations  61 B. In this manner, rear cover  10  and camshaft phaser assembly  1  is oriented and assembled with concentric camshaft assembly  2  in a desired orientation. By using protrusions  11  and indentations  61  to orient camshaft phaser assembly  1  with concentric camshaft assembly  2 , other orientation features, such as pins, may be eliminated. 
         [0024]    Rotor  40  is then connected to the inner camshaft  21  via central bolt assembly  80  which clamps the rotor  40  to the inner camshaft  21 . Central bolt assembly  80  includes a valve assembly  81  for directing pressurized hydraulic fluid to the first set of chambers  44  for rotating the rotor  40  in an advancing direction relative to the stator  50  in order to advance the timing of the inner camshaft  21 , or to the second set of chambers  46  in order to rotate the rotor  40  in a direction to retard the timing of the inner camshaft  21 . Hydraulic fluid can be applied to both the first and second sets of chambers  44 ,  46  in order to hydraulically lock the rotor  40  in a generally fixed position relative to the stator  50 . An electromagnetic solenoid (not shown) is used in order to adjust the position of the valve spool  82  to direct pressurized hydraulic fluid to the passages  84 ,  85  as required. The valve spool  82  is biased to an initial position via a spring  86  which rests on a shoulder within the central bolt assembly  80 . Pressurized hydraulic fluid is provided to the central bolt assembly  80  via pressurized hydraulic fluid being delivered through the inner camshaft  21 . This travels past a check valve  87  and through a filter  88  of the central bolt assembly  80  prior to reaching the valve spool  82  which directs the pressurized hydraulic fluid to the passages  84 , 85  or to a drain back to the engine oil reservoir. 
         [0025]    A helical spring  100  acts between the stator  50 , via at least two of the assembly bolts  55  that engage the spring  100 , and the rotor  40 , via front cover  60 . The spring  100  rotates the rotor  40  to a selected base position. 
         [0026]    The camshaft phaser  1  is preassembled as a unit that can be installed in one piece on the front end of the concentric camshaft assembly  2  by aligning protrusions  11  with indentations  61 , more particularly, by aligning for example first protrusion  11 A with mating indentation  61 A, second protrusion  11 B with second indentation  61 B and so on. The central bolt assembly  80  is then used to clamp the rotor  40  to the inner camshaft  21  and holds the entire phaser  1  in position axially on the front end of the concentric camshaft assembly  2 . 
         [0027]    It will be appreciated that various of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.