Abstract:
A configuration of a camshaft phaser ( 1 ), having a drive sprocket ( 2 ), a stator ( 3 ) and a rotor ( 4 ), the hydraulic channels ( 5 ) and ( 14 ) being formed by contact surfaces ( 7 ) of the axially contiguous components, such as the drive sprocket ( 2 ), the stator ( 3 ) and the rotor ( 4 ), as well as by recesses ( 6 ).

Description:
BACKGROUND 
       [0001]    Camshaft phasers are used in combustion engines to vary the valve timing of the combustion chamber valves. Consumption and emissions are reduced by adapting the valve timing to the actual load. One common type is the vane-type adjuster. Vane-type adjusters have a stator, a rotor and a drive sprocket. For the most part, the rotor is nonrotatably connected to the camshaft. The stator and the drive sprocket are likewise interconnected, the rotor being disposed coaxially to and within the stator. The rotor and stator form oil chambers which can be pressurized by oil and which make possible a relative movement between the stator and rotor. In addition, the vane-type adjusters include various sealing covers. A plurality of screw connections are used to interconnect the stator, the drive sprocket and the sealing cover. 
         [0002]    A multiplicity of radially configured bores in the rotor are used for supplying oil to the oil chambers. They lead, on the one hand, into the oil chambers and, on the other hand, into the hub of the rotor; this being supplied, in turn, with oil from the end of the camshaft. 
       SUMMARY OF THE INVENTION 
       [0003]    It is an object of the present invention to provide a camshaft phaser that has an oil guidance that is especially simple to manufacture. 
         [0004]    The present invention provides a camshaft phaser has a drive sprocket, a stator and a rotor, the rotor and the stator forming two working chambers which act counter to one another to effect the rotation of the rotor relative to the stator, and the stator being torsionally fixed relative to the drive sprocket in a way that allows at least two of the aforementioned components (drive sprocket, stator and rotor) to be configured to be directly axially contiguous, and, via the formed contact surfaces thereof, to define a common hydraulic channel that leads into one of the working chambers. 
         [0005]    To form a hydraulic channel, two components are configured axially contiguously. At least one of the components used has a depression. This depression may extend predominantly radially from the hub of the camshaft phaser to a first working chamber that it leads into. The counterpart on the other component used may feature a plane surface or likewise a depression. If both components are configured axially contiguously, then a hydraulic channel is formed in the plane of separation. The hydraulic channel is bounded by the contact surfaces that are configured in the immediate vicinity of the depression. These contact surfaces seal the hydraulic channel from the ambient environment. 
         [0006]    This objective is achieved in accordance with the present invention in that the camshaft phaser has a drive sprocket, a stator and a rotor, the rotor and the stator forming two working chambers which act counter to one another to effect the rotation of the rotor relative to the stator, and the stator being torsionally fixed relative to the drive sprocket, in such a way that at least two of the aforementioned components (drive sprocket, stator and rotor) are configured to be indirectly axially contiguous and to define a common hydraulic channel that leads into one of the working chambers. 
         [0007]    The components used for forming a hydraulic channel may be constituted of a drive sprocket, a stator, a rotor, a cover, a covering, a disk or a cap. The axial configuration of the components used is reminiscent of a sandwich construction of the camshaft phaser. The hydraulic channels formed for the respective working chambers extend substantially radially. Other hydraulic channels, for example, for supplying oil for locking or venting are conceivable in other designs. 
         [0008]    The hydraulic channels may be formed by depressions in one of the components. The depression includes corrugations, creases, hollows, slots, indentations or other recessed formations. When the components are joined together, hydraulic passages are formed that are substantially oil-tight relative to the ambient environment. These passages extend directly radially or, as a combination of axial and radial orientation, from an oil inflow, mostly in the hub of the camshaft phaser, to the associated working chamber. The cross section formed by the two components for the passage of hydraulic media is advantageously constant in shape. Alternatively, a local, specially adapted cross section, for example, for forming baffles, nozzles or diffusers may be provided. 
         [0009]    Moreover, both components may have depressions which, in combination with one another, form a fluid-conducting channel. Upon joining of the two components, two depressions, which (considered in cross section) are largely semicircular, for example, are configured to form a channel, which (considered in cross section) is largely circular. 
         [0010]    The components used for forming a hydraulic channel are advantageously formed as a sheet-metal part, at least one component being able to have a depression. The depression is produced in a noncutting process by stamping, collaring, deepdrawing or extrusion. The depression features a constant or variable cross section of the wall thereof. 
         [0011]    A hydraulic channel formed leads into a first working chamber. This fluid-conducting connection supplies the working chamber with pressure oil in order to rotate the rotor against the stator in an advantageous direction. In the case of pressure cutoff, this formed oil channel may be utilized as an outlet for oil and air to evacuate the first working chamber. 
         [0012]    One positive aspect is that the depression enlarges the surface area, thereby promoting a transfer of heat. The oil is thereby adapted to the ambient temperatures. Thus, a stable viscosity of the oil is achieved, enabling the camshaft phaser to function with greater thermostability. 
         [0013]    A stiffening effect is achieved by the formation of depressions in the sheet metal of at least one of the components used. The stability of the component is enhanced, and material may be economized, which is beneficial in terms of achieving a lightweight construction. 
         [0014]    One preferred embodiment of the present invention provides that the rotor have a vane on which a recess is configured. This recess opens an access for hydraulic oil into a working chamber. The recess is advantageously formed in a rotor of sheet metal and, once joined to an axial, peripheral component, forms a fluid-conducting hydraulic channel. Alternatively, this recess may also be configured near the outer peripheral surface of the rotor. 
         [0015]    The recess may also be produced by punching. An embodiment as a sintered or cast part is also possible. Further methods include milling, turning on a lathe, erosion and other metal-cutting methods. 
         [0016]    By selectively configuring the recess on the vane, it is possible to influence the flow characteristics into and out of the working chamber. These are determined by a radial positioning of the recess. In the process, a damping effect may be achieved, or a desired residual quantity of oil may remain in the working chamber. 
         [0017]    One embodiment of the present invention also provides for the camshaft phaser to have a locking mechanism that couples the rotor to the stator nonrotatably. Two axially contiguous components are configured to form a hydraulic channel that extends from a hub of the camshaft phaser to the locking mechanism. 
         [0018]    Separating an oil channel over two components, which, only when combined, form a shared oil channel along the direction of flow, makes it possible to use simple manufacturing processes and simplify quality control. Unwanted effects are also reduced, as the impurities causing them are more readily removed from crimps, corrugations, depressions and openings. Manufacturing and quality are thus significantly improved by joining a plurality of components that have the oil-conducting features. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    Exemplary embodiments of the invention are illustrated in the figures, which show: 
           [0020]      FIG. 1  a section through the camshaft phaser; 
           [0021]      FIG. 2  a cross section of  FIG. 1  without a rotor; 
           [0022]      FIG. 3  a cross section of  FIG. 1  with a rotor; 
           [0023]      FIG. 4  a further section through the camshaft phaser; and 
           [0024]      FIG. 5  a configuration including a stator, a rotor and a hub. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]      FIG. 1  shows a camshaft phaser  1 , which has a drive sprocket  2 , including a nonrotatably connected stator  3 , and is concentrically configured relative to a rotor  4 . Drive sprocket  2  and rotor  4  are mounted on a hub  11 . Together with rotor  4 , stator  3  forms working chambers  9 ,  10  which may be hydraulically pressurized. These working chambers act counter to one another and are supplied via a hydraulic channel  5  with pressure oil. This hydraulic channel  5  is formed by rotor  4  and drive sprocket  2 . Drive sprocket  2  has wall portions  2   a,    2   b  of various thicknesses. Wall portions  2   a,    2   b  are configured at the front end together with rotor  4  and open, respectively cover the feed lines. 
         [0026]      FIG. 2  shows a cross-section through  FIG. 1 . Rotor  4  is not depicted here in order to provide a view of hydraulic channels  5 . The outline of wall portion  2   a,  whose thickness is greater is than that of wall portion  2   b,  coherently follows the inner contour of stator  3  in the corresponding angular segment. This geometry is configured at least four times in the 45° angle. The axial offset created by the different thicknesses of wall portions  2   a  and  2   b  produces an axial depression, forming a hydraulic channel  5 . 
         [0027]      FIG. 3  shows a cross section from  FIG. 1 , including rotor  4 . The axial contact surface of rotor  4  with drive sprocket  2  is formed in the regions of wall portions  2   a.  Since rotor  4 , together with the wall thereof, extends between the wall of stator  3  and hub  11 , rotor  4  seals working chamber  9  from working chamber  10  and only allows an inflow into working chamber  10  through hydraulic channel  5  that is directly limited by rotor  4 , stator  3  and drive sprocket  2 . 
         [0028]      FIG. 4  shows the configuration of a camshaft phaser  1  according to  FIG. 1 , including an angularly offset cross section through hydraulic-medium feed line  16 . Together with a recess  6 , rotor  4  forms a hydraulic channel  14 . Rotor  4  and drive sprocket  2  are axially contiguous and form contact surfaces  7 . Together, recess  6  and drive sprocket  2  form a hydraulic channel  14 . Contact surfaces  7  seal hydraulic channel  14 , ensuring a defined position of the feed line. Rotor  4  also has a locking mechanism  12 . Locking mechanism  12  arrests, respectively releases rotor  4  with stator  3  in the direction of rotation of camshaft phaser  1 . A supplying of hydraulic oil for actuating locking mechanism  12  may be provided by an inventive design of a hydraulic channel. 
         [0029]      FIG. 5  shows a stator  3  having a coaxially configured rotor  4  disposed therein. Stator  3  and rotor  4  form working chambers  9 ,  10  which act counter to one another and may be acted upon by pressure oil. The configuration shown here originates from camshaft phaser  1  in accordance with FIG. I and  2 . Rotor  4  and stator  3  are mounted on a hub  11 . Pressure oil, respectively hydraulic medium flows from hydraulic-medium feed line  15  of hub  11  into circumferential groove  17  and spreads over the periphery. In addition, the pressure oil then flows through vane  8 , which is permanently joined in one piece to rotor  4 , to recess  6 , which, together with drive sprocket  2  (not shown here), forms a hydraulic channel  14 . The pressure oil, respectively hydraulic medium is supplied through hydraulic channel  14  according to the present invention into working chamber  9 . Working chamber  10  is supplied through hydraulic channel  5  in  FIG. 1 . 
       LIST OF REFERENCE NUMERALS 
       [0030]      1 ) camshaft phaser 
         [0031]      2 ) drive sprocket 
         [0032]      2   a,    2   b ) wall portions 
         [0033]      3 ) stator 
         [0034]      4 ) rotor 
         [0035]      5 ) hydraulic channel 
         [0036]      6 ) recess 
         [0037]      7 ) contact surface 
         [0038]      8 ) vane 
         [0039]      9 ) working chamber 
         [0040]      10 ) working chamber 
         [0041]      11 ) hub 
         [0042]      12 ) locking mechanism 
         [0043]      13 ) hydraulic channel 
         [0044]      14 ) hydraulic channel 
         [0045]      15 ) hydraulic-medium feed line 
         [0046]      16 ) hydraulic-medium feed line 
         [0047]      17 ) groove