Abstract:
The invention relates to an oscillating motor adjuster having a driven stator, which is followed by a first rotor via a first hydraulic power transmission path, which is followed by a second rotor via a second hydraulic power transmission path. The second rotor is joined in a torsionally rigid manner to a second camshaft part, which is disposed coaxially to a first camshaft part, which is joined in a torsionally rigid manner to the first rotor. The relative angular position of the two rotors to one another can be adjusted very accurately by this sequential arrangement of the two rotors.

Description:
[0001]    This application claims the benefit of German patent application number DE 10 2011 001 301.6 filed on Mar. 16, 2011, which is incorporated herein by reference in its entirety and for all purposes. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to an oscillating motor adjuster for a two-part camshaft. Oscillating motor adjusters for adjusting two-part camshafts are known from DE 36 248 27 A1, DE 10 2005 014 680 A1, DE 10 2006 041 918 A1, and U.S. Pat. No. 6,725,817 B2. 
         [0003]    DE 100 45 416 B4 relates to an oscillating motor adjuster in which a pin of a housing is plugged into a central recess of the rotor. Thus, the rotor of the oscillating motor adjuster is disposed in a rotatable manner relative to the pin that is stationary in the housing. Oil can be introduced from a 4/3-way hydraulic valve into the oscillating motor adjuster via channels in the housing and in the pin, so that the rotor can be pivoted or oscillated into two opposite oscillating directions relative to a stator. 
         [0004]    Unpublished DE 10 2011 000 650.8 relates to an oscillating motor adjuster in which oil is introduced from a housing radially outside into a stator of the oscillating motor adjuster. 
       SUMMARY OF THE INVENTION 
       [0005]    The object of the present invention is to create an oscillating motor adjuster that makes possible an adjustment of a two-part camshaft having an inner shaft and an outer shaft. 
         [0006]    This object is achieved in accordance with the embodiments of the present invention disclosed herein. 
         [0007]    According to the present invention, two rotors are disposed sequentially to one another. That is, a first rotor follows the stator driven by a crankshaft via a first hydraulic power transmission path, while a second rotor follows via a second hydraulic power transmission path. In this case, the first rotor is joined resistant to rotation to the first camshaft part, while on the other hand, the second rotor is joined resistant to rotation to the second camshaft part. The two camshaft parts are disposed coaxially to one another. 
         [0008]    The sequential oscillating motor adjuster according to the present invention has the advantage that the second rotor is directly dependent on the first rotor in its manufacturing tolerances or in its angular position. In this way, two tolerances need not be taken into consideration for the relative angular position of the two rotors, but rather only one tolerance. Therefore, the relative angular position of the two rotors to one another can be adjusted very accurately. 
         [0009]    Another advantage provided by the present invention is that the sequential oscillating motor adjuster according to the invention makes possible a very rapid adjustment. Thus, the inner rotor is necessarily very small for the given installation conditions. A small rotor means a small oil volume in the pressure chambers, which is accompanied by a very rapid adjustment. The disadvantage associated with a small rotor in the prior art is that the friction component is greater, but this plays no role in the oscillating motor adjuster according to the invention. That is, the inner rotor has a very small basic friction, since part of the adjustment for loads takes place in the radially outer (i.e., first) rotor. 
         [0010]    The two parts of the camshaft can be designed as a hollow shaft and an inner shaft disposed within the latter. The use of a central screw without a central valve disposed within this central screw makes it possible to brace the central screw in the small cross section of the inner shaft strongly enough that sufficient torque can be transmitted. 
         [0011]    In one example embodiment of the present invention, a housing is provided, which can be, in particular, a housing rigidly joined with the cylinder head or a housing part of a cylinder head cap or the cylinder head itself. The stator is mounted in a rotatable manner in a housing borehole of this housing. Oil can be introduced by means of annular grooves in a stator outer wall having oil boreholes or oil channels exiting from these annular grooves into pressure chambers assigned to opposite oscillating directions. In this case, preferably a separate oil borehole or a separate oil channel, which introduces the oil, is allotted to each pressure chamber. This makes possible an integration of the rotary leadthrough into the stator, which, in contrast, is designed separately in the prior art. The radial dimensions of the oscillating motor adjuster can be small. Also, the axial structural space can be short. In this way, the oscillating motor adjuster will be very small. An oil feed via the camshaft is not necessary, so that the camshaft need not be weakened by means of cross boreholes. 
         [0012]    When compared with an oil supply via the camshaft or a camshaft bearing, the hydraulic paths are very short, so that hydraulic losses are also small. This is then particularly advantageous when camshaft alternating torques are utilized for a more rapid adjustment of the camshaft. Additional boreholes in the rotor hub are not absolutely necessary. In a particularly advantageous manner, dirt particles are pressed radially outward from the pressure chambers as a consequence of centrifugal force. 
         [0013]    Additional advantages of the invention are derived from the patent claims, the description and the drawing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The present invention will hereinafter be described in conjunction with the appended drawing figures, wherein like reference numerals denote like elements, and: 
           [0015]      FIG. 1  shows an example embodiment of an oscillating motor adjuster in accordance with the present invention in a section along a longitudinal axis. 
           [0016]      FIG. 2  shows the oscillating motor adjuster of  FIG. 1  in a section along line II-II of  FIG. 1 ; and 
           [0017]      FIG. 3  shows the oscillating motor adjuster of  FIG. 1  in a view without a cover plate and without a housing. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    The ensuing detailed description provides exemplary embodiments only, and is not intended to limit the scope, applicability, or configuration of the invention. Rather, the ensuing detailed description of the exemplary embodiments will provide those skilled in the art with an enabling description for implementing an embodiment of the invention. It should be understood that various changes may be made in the function and arrangement of elements without departing from the spirit and scope of the invention as set forth in the appended claims. 
         [0019]    The angular position of a two-part camshaft  2  can be continuously changed relative to a drive wheel  3  during the operation of an internal combustion engine by an oscillating motor adjuster  1  according to  FIG. 1 . By rotating camshaft  2 , the opening and closing time points of the gas exchange valves are shifted so that the internal combustion engine offers its optimal performance at the rpm involved. In this case, a radially outer camshaft part  17  designed as a hollow shaft  14  is joined with first cams  19 ,  20  for control of the gas exchange valves. For this purpose, cams  19 ,  20  are shrunk-fit onto the radially outer camshaft part  17 , for which an additional micro-gearing can be provided. A radially inner camshaft part  18 , which is designed as a solid shaft  21 , is also joined to cams, which are not shown in further detail. These cams, which are not shown in further detail, however, are joined via a pin connection to the radially inner camshaft part  18  and mounted on the radially outer camshaft part  17 . Such a pin connection has already been presented in DE 10 2005 014 680 A1, to which reference is made herewith. 
         [0020]    The oscillating motor adjuster  1  has a stator  4 , which is joined in a torsionally rigid manner to drive wheel  3 . For this purpose, a screw connection is provided, which has several screws  22 . These screws  22  brace a stator  4  between a cover plate  23  and drive wheel  3 . Drive wheel  3  is a chain wheel with a gearing  33 , over which a chain, which is not shown in more detail, is guided as the drive element. Stator  4  is drive-connected to the crankshaft by means of this drive element and drive wheel  3 . 
         [0021]    Stator  4  also comprises a cylindrical stator outer wall  5 , which is visible in  FIG. 2 , and crosspieces  8  project radially inward at equal distances from the inner side of this wall. Between adjacent crosspieces  8 , intermediate spaces are formed, into which oil is introduced as a pressure medium. For this purpose, a first proportional 4/3-way hydraulic valve  12  is provided, which is explained further below and which correspondingly controls the pressure medium. 
         [0022]    Vanes  9 , which protrude radially toward the outside from a cylindrical housing wall  10  of an intermediate rotor  11 , project between adjacent crosspieces  8 . These vanes  9  subdivide the intermediate spaces between crosspieces  8  each time into two pressure chambers  31 ,  32 , of which pressure chambers  32  in  FIG. 2  and  FIG. 3  are reduced to a minimum. In the position of the first proportional 4/3-way hydraulic valve  12 , which is shown in  FIG. 2 , pressure chambers  31  are loaded with hydraulic pressure, while in contrast, pressure chambers  32  are relieved of pressure toward a tank  24 . 
         [0023]    Crosspieces  8  are applied tightly by their front sides to the outer surface  25  of housing wall  10 . Vanes  9  in turn are applied tightly by their front sides to the cylindrical inner wall  6  of stator outer wall  5 . 
         [0024]    Intermediate rotor  11  takes over the function of an inner stator  27  for an inner rotor  26 . For this purpose, radially inwardly directed inner crosspieces  28  project at equal distances from housing wall  10  of intermediate rotor  11  on its inner side. Intermediate spaces are formed between adjacent inner crosspieces  28 . Inner rotor  26  separates these intermediate spaces each time into a first pressure chamber  68  and a second pressure chamber  69  assigned to opposite oscillating directions. As the pressure medium, oil can be introduced into or discharged from the two pressure chambers  68 ,  69 . For this purpose, a second proportional 4/3-way hydraulic valve  60  is provided, which is explained further below and which correspondingly controls the oil as the pressure medium. 
         [0025]    The inner rotor  26  is disposed so that it can oscillate inside intermediate rotor  11  and is joined in a torsionally rigid manner to the inner camshaft part  18  of camshaft  2  by means of a central screw  34  that is visible in  FIG. 1 . For this purpose, this central screw  34  is plugged into camshaft  2  through a central recess  35  of a rotor hub  29  of inner rotor  26  and screwed with an inner thread  16  of inner camshaft part  18 . In this case, a screw head  30  of central screw  34  is applied to a base  36  of central recess  35  and thus braces drive wheel  3  against a front side  37  of hollow shaft  14 , which forms the outer camshaft part  17 . Drive wheel  3  is rigidly screwed to stator  4  and cover plate  23  by means of screws  22 . Additional screws  38  produce a solid connection between intermediate rotor  11  and a plate  39 , which is mounted coaxially to hollow shaft  14  and is applied to drive wheel  3 . In this way, screws  38  produce a torsionally rigid connection to hollow shaft  14 . This torsionally rigid connection is a flange joint. 
         [0026]    The inner camshaft part  18  has a blind borehole  40  in which inner thread  16  is cut. On the side turned toward oscillating motor adjuster  1 , inner camshaft part  18  is sealed relative to hollow shaft  17  by means of an O-ring  41 . In order to minimize friction, inner camshaft part  18  has an annular gap  42  relative to hollow shaft  14 . 
         [0027]    A pin-shaped component  13 , which is pressed into a housing  15  in a way that is not shown in detail, is provided inside the recess  35 , this pin-shaped component  13  having an A 1  channel  43  that conducts oil to one of the pressure chambers. Separate from this A 1  channel  43 , a B 1  channel  44  is provided, which conducts oil to the other pressure chamber. Pin-shaped component  13 , which is fixed in the housing, is inserted into the only partially shown housing  15 , which is joined resistant to movement to the cylinder head, which is not shown in more detail. Pin-shaped component  13  has two annular channels  45 ,  46  surrounding the component  13  in ring-shaped manner. Al channel  43  opens up into one annular channel  45 . B 1  channel  44  opens up into the other annular channel  46 . Sealing rings that are axially adjacent to the two annular channels  45 ,  46  are inserted into annular grooves  47 ,  48 ,  49 . In this case, only one common sealing ring is disposed axially in annular groove  48  between the two annular channels  45 ,  46 . Since in these sealing rings a continuous rotational movement takes place on the respective sealing ring, these sealing rings, which are not shown in the drawing, are designed correspondingly as insensitive to sliding friction On the front side turned toward camshaft  2 , the pin-shaped component  13  is designed with a recess  50 , inside of which screw head  30  extends, so that the oscillating motor adjuster  1  can be built having a very short length. 
         [0028]    On its outer periphery, stator  4  also has two annular channels  51 ,  52  axially distanced from one another. The annular channel  51  bounded by cover plate  23  is assigned to an A 2  channel  53 , which conducts oil from housing  15  to one of the pressure chambers. The annular channel  52 , which is placed closer to drive wheel  3 , in contrast, is assigned to a B 2  channel  54 , which conducts oil from housing  15  to the other pressure chamber. 
         [0029]    A first lock  55  is provided in one vane of vanes  9 , with which the intermediate rotor  11  can be attached in form-fitting manner to stator  4 . One vane of vanes  57  of inner rotor  26  has a second lock  58 , with which the inner rotor  26  can be attached to intermediate rotor  11 . 
         [0030]    Cover plate  23  has a spiral-shaped compensation spring  59  on its side facing away from camshaft  2 . This compensation spring  59  attempts to keep inner rotor  26  at a specific angular position relative to stator  4 . 
         [0031]    In this case, the A 2  channel  53  is assigned to a first working port A, while in contrast, the B 2  channel  54  is assigned to a second working port B. 
         [0032]    Housing  15  has a large housing borehole  61 , in which stator  4  is mounted in a rotatable manner. In order to keep leakage losses as small as possible, sealing rings  62 ,  63 ,  64  are provided. These sealing rings  62 ,  63 ,  64  are inserted into annular grooves  65 ,  66 ,  67 , which are disposed axially distant from the A 2  channel  52  and the B 2  channel  54 . In this way, the middle sealing ring  63  is disposed axially in annular groove  66  between the A 2  channel  52  and the B 2  channel  54 . The two axially outer sealing rings  62 ,  64  seal annular groove  65  and/or annular groove  67  toward the outside. 
         [0033]    The two proportional 4/3-way hydraulic valves  12 ,  60  have a locking center position. The two proportional 4/3-way hydraulic valves  12 ,  60  are supplied with oil pressure by a common oil pump. A holding pressure for intermediate rotor  11  and inner rotor  26  is produced by means of a run-off edge control as has already been described in DE 198 23 619 A1. Control of the 4/3-way hydraulic valves  12 ,  60  is produced electromagnetically. Both 4/3-way hydraulic valves  12 ,  60  are disposed in a decentralized manner, i.e., not coaxially to an axis of rotation  56  of the oscillating motor adjuster. 
         [0034]    In an alternative example embodiment of the invention, it is also possible to dispose the 4/3-way hydraulic valve assigned to inner rotor  26  as a central valve inside rotor hub  29 . 
         [0035]    The closer the respective 4/3-way hydraulic valve  12  or  60  is disposed relative to intermediate rotor  11  or rotor  26  to be adjusted, the more it lends itself to provide a system for utilizing the camshaft alternating torques in the respective 4/3-way hydraulic valve  12  or  60 . Such a system for utilizing camshaft alternating torques is known from DE 10 2006 012 733 B4. 
         [0036]    In an alternative example embodiment, the drive wheel is a toothed belt gear, over which a drive belt is guided as a drive element. 
         [0037]    Basically, sintered steel, plastic or light metal are considered as materials for the various parts of the motor adjuster, including the rotors, drive wheel, stator, cover plate, and the like. Steel sheet material may also be used for the cover plate, the drive wheel or the like where only thin walls are required. A plastic, in particular, can be a duroplast with mineral powder inclusions and fiber inclusions. A light metal, in particular, can be aluminum or magnesium. 
         [0038]    In another alternative example embodiment of the present invention, the oil may be guided via a camshaft bearing and the camshaft to the working ports in the oscillating motor adjuster. Such a camshaft comprising an inner shaft and an outer shaft with hydraulic pressure supply via a camshaft bearing and a central valve in the camshaft adjuster is already known from DE 10 2006 024 793 A1, to which reference is made herewith. In contrast to this, a decentralized valve, which introduces hydraulic pressure into the camshaft adjuster via channels in the camshaft bearing, is provided in the case of DE 10 2006 028 611 A1. 
         [0039]    The internal combustion engine can be either a gasoline engine or a diesel engine. 
         [0040]    For the sealing rings on the pin-shaped component  13  or on the stator  4 , sealing rings that permit a permanent tightness in the case of rotation can be provided. In addition to plastic, metal can also be used here as a material. 
         [0041]    The pin-shaped component  13  need not be stationary relative to the rotating inner rotor  26 . It is also possible that this component rotates with the rotor  26  and, in fact, is made up in one piece with it. In this case, for example, the pin-shaped component  13  can extend from the rotor and the camshaft and be mounted in a rotatable manner in housing  15 . The oil can then be transferred again via annular grooves that are disposed in housing  15  or on the pin-shaped component  13 . The arrangement of the annular grooves on the pin-shaped component  13  has the advantage that an outer processing is more cost-effective than an unscrewing from inner annular grooves from a borehole in housing  15 . 
         [0042]    It is also possible to provide a central valve instead of the pin-shaped component  13 . This central valve can be plugged into the rotor hub from the outside, i.e., the side facing away from the camshaft. This central valve may also be designed as a central screw and thus assumes the function of central screw  34 . 
         [0043]    The oil inlet shown in the drawing for inner rotor  26  is also called a front-side oil supply, which is contrasted to the oil supply of the outer rotor on the outer periphery. 
         [0044]    The inner camshaft part that is designed as a solid shaft in the example embodiment may also be designed as a hollow shaft. DE 10 2006 013 829 A1 shows such an inner camshaft part designed as a hollow shaft. 
         [0045]    The above-described embodiments only involve exemplary configurations. A combination of the described features for different embodiments is also possible. Additional features, particularly those which have not been described, for the device parts belonging to the invention can be derived from the geometries of the device parts shown in the drawings. 
       LIST OF REFERENCE CHARACTERS 
       [0046]      1  Oscillating motor adjuster 
         2  Camshaft 
       [0047]      3  Drive wheel 
         4  Stator 
       [0048]      5  Outer wall of the stator
 
 6  Inner wall
 
         8  Crosspieces 
       9  Vane(s) 
       [0049]      10  Housing wall
 
 11  Intermediate rotor
 
 12  4/3-Way hydraulic valve
 
 13  Pin-shaped component
 
 14  Hollow shaft
 
         15  Housing 
       [0050]      16  Inner thread
 
 17  Radially outer camshaft part
 
 18  Radially inner camshaft part
 
         19  Cam 
       20  Cam 
       [0051]      21  Solid shaft 
         22  Screws 
       [0052]      23  Cover plate 
         24  Tank 
       [0053]      25  Outer surface
 
 26  Inner rotor
 
 27  Inner stator
 
 28  Inner crosspieces
 
         29  Rotor hub 
       [0054]      30  Screw head
 
 31  Pressure chambers
 
 32  Pressure chambers
 
         33  Gearing 
       [0055]      34  Central screws
 
 35  Central recess
 
         36  Base 
       [0056]      37  Front side
 
 38  Additional screws
 
         39  Plate 
       [0057]      40  Blind borehole 
         41  O-ring 
       42  Annular gap 
       [0058]      43  A 1  channel
 
 44  B 1  channel
 
 45  Annular channel
 
 46  Annular channel
 
 47  Annular groove
 
 48  Annular groove
 
 49  Annular groove
 
         50  Recess 
       [0059]      51  Annular channel
 
 52  Annular channel
 
 53  A 2  channel
 
 54  B 2  channel
 
 55  First lock
 
 56  Axis of rotation
 
         57  Vane(s) 
       [0060]      58  Second lock
 
 59  Compensation spring
 
 60  4/3-Way hydraulic valve
 
 61  Housing borehole
 
 62  Sealing ring
 
 63  Sealing ring
 
 64  Sealing ring
 
 65  Annular groove
 
 66  Annular groove
 
 67  Annular groove
 
 68  Pressure chambers
 
 69  Pressure chambers