Patent Publication Number: US-8978609-B2

Title: Oscillating motor adjuster

Description:
RELATED/PRIORITY APPLICATION 
     This application relies upon German Application No, 10 2012 112 059.5, filed on Dec. 11, 2012, for priority. 
     The invention relates to an oscillating motor adjuster having the features mentioned in the claims. 
     An oscillating motor adjuster is used during operation of a combustion engine to steplessly change the angular position of the camshaft relative to a drive wheel. By twisting of the camshaft, the opening and closure times of the gas-exchange valves are offset sin such a way that the combustion engine performs optimally for the respective rotation speed. Oscillating motor adjusters have a stator  1 , which is non-rotatably connected to the drive wheel. Within the stator, a rotor is arranged which is non-rotatably connected to the camshaft and can be displaced relative to the stator by hydraulic pressure on one of its two rotor connections. The hydraulic pressure is supplied by a central valve inserted in the camshaft, at the first or second working connection of said valve. 
     The aim of the present invention is to demonstrate a way of connecting the working connections of the central valve cost-effectively each with one of the two rotor connections. 
     This aim is achieved with an oscillating motor adjuster having the features mentioned in the independent claim. Advantageous further developments of the invention are the subject of subordinate claims. 
     In an oscillating motor adjuster according to the invention, the working connections of the central valve are connected to the rotor connections via an annular chamber. To this end, an annular chamber between central valve and rotor is divided by a sleeve into two annular chambers, each of which connects one of the two working connections to one of the rotor connections. The two annular chambers are each sealed on the one hand from the central valve and on the other from the rotor. Hydraulic pressure on a working connection of the central valve is thus transmitted to the associated rotor connection, with the result that the angular position of the rotor can be controlled relative to the stator. 
     The two areas of sealing on the sleeve, that is, to the central valve and to the rotor, can be sealed with sealing rings. Preferably only one of the two areas of sealing is sealed with a sealing ring, while the other area of sealing is sealed by press fitting of the sleeve. For example, a sealing ring may be positioned between the sleeve and the central valve and the sleeve be pressed into the hub of the rotor. In this way, especially cost-effective manufacture is possible, since the sleeve is manufactured at low cost, for example by deep-drawing from sheet metal, and need only be centred relative to the rotor. Manufacturing and positioning tolerances of the sleeve relative to the central valve enclosed by the sleeve may be compensated with a sealing ring, for example, an O-ring. 
     An advantageous further development of the invention provides for the sleeve to project from the rotor. For example, a portion of the sleeve projecting from the rotor may have an annular shoulder in which there is a recess into which a projection of the rotor engages. In this way, positioning of the sleeve relative to the rotor is made easier, and twisting of the sleeve relative to the rotor is prevented. 
     The sleeve may be manufactured as, for example, a doubly-drawn deep-drawn part. The sleeve preferably has three cylindrical portions, for example, a first cylindrical portion which presses a sealing ring against the central valve, a second cylindrical portion which is in contact with the rotor, and a third cylindrical portion, outside the rotor. In this arrangement, the diameter of the second cylindrical portion is preferably larger than the diameter of the first cylindrical portion and the diameter of the third cylindrical portion is larger than the diameter of the second cylindrical portion. 
     Further details and advantages of the invention are illustrated in the embodiment, with reference to the attached drawings. 
    
    
     
       The drawings are as follows: 
         FIG. 1  A cross-sectional view of an oscillating motor adjuster, and 
         FIG. 2  The oscillating motor adjuster in longitudinal section. 
     
    
    
     With an oscillating motor adjuster  14  according to  FIGS. 1 and 2 , during operation of a combustion engine the angular position of the camshaft  18  is steplessly changed relative to a drive wheel  2 . By twisting of the camshaft  18 , the opening and closure times of the gas-exchange valves are offset in such a way that the combustion engine performs optimally for the respective rotation speed. The oscillating motor adjuster  14  has a cylindrical stator  1  which is non-rotatably connected to the drive wheel  2 . In the example embodiment, the working wheel  2  is a chain wheel, over which a chain—not shown in greater detail—is guided. However, the drive wheel  2  may also be a toothed belt wheel over which a drive belt is guided as the drive element. Via this drive element and the drive wheel  2 , the stator  1  is drivably connected to the crankshaft. 
     The stator  1  comprises a cylindrical stator base body  3 , on the inside of which base body crosspieces  4  project radially inwards at equal distances. Between adjacent crosspieces  4 , intermediate chambers  5  are formed, into which pressure medium  5  is introduced, controlled by a central valve  12  shown in detail in  FIG. 2 . Vanes  6 , jutting radially outwards from a cylindrical rotor hub  7  of a rotor  8 , rise up between adjacent crosspieces  4 . These vanes  6  divide the intermediate chambers  5  between the crosspieces  4  in each case into two pressure chambers  9  and  10 . The one pressure chamber  9  is associated with adjustment in the “early” direction, whereas the other pressure chamber is associated with adjustment in the “late” direction. 
     The crosspieces  4  are positioned on the outer casing surface of the rotor hub  7  with their front faces forming a seal. The vanes  6 , for their part, are positioned on the cylindrical internal wall of the stator base body  3  with their front faces forming a seal. 
     The rotor  8  is non-rotatably connected to the camshaft  18 . To change the angular position between the camshaft  18  and the drive wheel  2 , the rotor  8  is turned relative to the stator  1 . To this end, the pressure medium in the pressure chambers  9  or  10  is pressurised, depending on the desired direction of rotation, while the respectively other pressure chambers  9  or  10  are discharged into the tank via the tank connector T. To swivel the rotor  8  anticlockwise relative to the stator  1  into the position shown, a first annular chamber  19  is pressurised by the central valve  12  as an annular rotor channel in the rotor hub  7 . From this first rotor channel, further channels  11  then lead into the pressure chambers  10  as a first rotor connection. The first annular chamber  19  is associated with the first working connection A of the central valve  12 . By contrast, to swivel the rotor  8  in the clockwise direction, a second annular chamber  20  is pressurised by the central valve  12  as an annular rotor channel in the rotor hub  7 , into which annular rotor channel as a second rotor connection channels  13  have their opening. This second rotor channel  20  is associated with the second working connection B. These two annular chambers  19 ,  20  are arranged axially distanced from one another with respect to a central axis  22 , so that they are positioned concealed one behind the other in the plane of the drawing in  FIG. 1 . 
     The oscillating motor adjuster  14  is positioned on the camshaft, which is designed as a hollow shaft  16 . In addition, the rotor  8  is inserted on to the camshaft  18 . The hollow shaft  16  has boreholes for a tank connection T and a power supply connection V. Depending on the position of a hollow piston  28  arranged within the bushing  27 , one of the two working connections, A, B is connected either with the tank connection T or with the power supply connection, and therefore either the first rotor connection  11  or the second rotor connection  13  is impinged upon with hydraulic pressure. The rotor  8  is therefore displaced relative to the stator  1  on the first rotor connection  11  by hydraulic pressure in a first direction, and relative to the stator  1  on the second rotor connection  13  by hydraulic pressure in a second, opposite direction of rotation. 
     The two annular chambers  19 ,  20  are separated from one another in the axial direction by a sleeve  30 . The annular chambers  19 ,  20  are thus formed by division of an annular chamber between rotor  8  and central valve  12 . One of the two annular chambers  19  connects the first working connection A to the first rotor connection  11 , and the other annular chamber  20  connects the second working connections B with the second rotor connection  13 . 
     As  FIG. 2  shows, the diameter of the sleeve  30  increases between the two working connections A, B of the hydraulic central valve  12 . A sealing ring  31  is arranged between a first cylindrical portion of the sleeve  30  and the central valve  12 . The sealing ring  31  is arranged between the two working connections A, B and can sit in a groove of the central valve  12 . A second cylindrical portion of the sleeve  30 , which has a larger diameter than the first cylindrical portion, forms a seal on the rotor  8  with a press fit. The second cylindrical portion has openings for the passage of hydraulic fluid, in order to connect the working connection B to the second rotor connection  13  via the annular chamber  20 . 
     The sleeve  30  may project from the rotor  8 , for example with a third cylindrical portion, which has a larger diameter than the first and second cylindrical portion. Between the second cylindrical portion and the third cylindrical portion, the sleeve  30  has an annular shoulder. The annular shoulder has a recess into which a projection  32  engages in the axial direction. The sleeve  30  is therefore non-rotatably connected to the rotor  8 . 
     The embodiments described are given purely by way of example. A combination of the described features for different embodiments is also possible. Other features of the parts of the device belonging to the invention—in particular features which are not described—may be found in the geometries of the device parts shown in the drawings.