Abstract:
An adjusting device for camshafts of motor vehicles has a stator having radial inwardly projecting stays and a rotor having vanes projecting into spaces defined between the stays of the stator. The rotor is rotatable relative to the stator and the vanes of the rotor are loadable on opposed sides with a pressure medium. The rotor is lockable relative to the stator in a locked position, wherein the stator has at least one locking bore and the rotor has a locking element having a locking position in which the locking element engages the locking bore and locks the rotor in the locked position. The locking element is moveable by the pressure medium from the locking position into a release position.

Description:
BACKGROUND OF INVENTION 
     1. Field of the Invention 
     The invention relates to an adjusting device for camshafts, in particular, camshafts of motor vehicles, comprising a stator having radially inwardly projecting stays. A rotor is arranged rotatably relative the stator. The vanes of the rotor project into the space between the stays. The vanes of the rotor can be loaded on opposed sides by a pressure medium. 
     2. Description of the Related Art 
     By means of the adjusting device, the camshaft is adjusted by rotation of the rotor relative to the stator. When the motor is turned off, the rotor remains in its current position relative to the stator. When starting the engine again, this can cause problems when the rotor has assumed an unfavorable rotational position relative to the stator. 
     SUMMARY OF INVENTION 
     It is an object of the present invention to configure the adjusting device of the aforementioned kind such that, in a constructively simple and reliable way, the rotor has an optimal position relative to the stator when the engine is started. 
     In accordance with the present invention, this is achieved in that the rotor can be locked in a locked position relative to the stator, wherein the stator has at least one locking bore that is engaged by a locking element of the rotor, wherein the locking element is moveable by the pressure medium into its release position. 
     In the adjusting device according to the invention, the rotor is locked by the locking element relative to the stator. In this connection, the locking element is moved by the pressure medium into its release position and is advantageously also secured in this release position. By a suitable adjustment of the supply of the pressure medium, it is achieved that the locking element engages the locking bore of the stator when the rotor has reached a predetermined position relative to the stator. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a radial section of a part of the adjusting device according to the invention. 
         FIG. 2  is a section along the line II—II of  FIG. 1 . 
         FIG. 3  shows in a view corresponding to that of  FIG. 1  the adjusting device according to the invention in a first position. 
         FIG. 4  is a view corresponding to that of  FIG. 2  of the adjusting device in the position of  FIG. 3 . 
         FIG. 5  shows in a view corresponding to that of  FIG. 1  the adjusting device according to the invention in a second position. 
         FIG. 6  is a view corresponding to that of  FIG. 2  of the adjusting device in the position of  FIG. 5 . 
         FIG. 7  shows in view corresponding to that of  FIG. 1  the adjusting device according to the invention in a third position. 
         FIG. 8  is a view corresponding to that of  FIG. 2  of the adjusting device in the position of  FIG. 7 . 
         FIG. 9  shows in a view corresponding to that of  FIG. 1  the adjusting device according to the invention in a fourth position. 
         FIG. 10  is a view corresponding to that of  FIG. 2  of the adjusting device in the position of  FIG. 19 . 
         FIG. 11  shows in a view corresponding to that of  FIG. 1  the adjusting device according to the invention in a fifth position. 
         FIG. 12  is a view corresponding to that of  FIG. 2  of the adjusting device in the position of  FIG. 11 . 
         FIG. 13  shows in view corresponding to that of  FIG. 1  the adjusting device according to the invention in a sixth position. 
         FIG. 14  is a view corresponding to that of  FIG. 2  of the adjusting device in the position of  FIG. 13 . 
         FIG. 15  shows in a view corresponding to that of  FIG. 1  the adjusting device according to the invention in a seventh position. 
         FIG. 16  is a view corresponding to that of  FIG. 2  of the adjusting device in the position of  FIG. 15 . 
         FIG. 17  shows in a view corresponding to that of  FIG. 1  the adjusting device according to the invention in a eighth position. 
         FIG. 18  is a view corresponding to that of  FIG. 2  of the adjusting device in the position of  FIG. 17 . 
         FIG. 19  shows in a view corresponding to that of  FIG. 1  the adjusting device according to the invention in a ninth position. 
         FIG. 20  is a view corresponding to that of  FIG. 2  of the adjusting device in the position of  FIG. 19 . 
         FIG. 21  shows in a view corresponding to that of  FIG. 1  the adjusting device according to the invention in a tenth position. 
         FIG. 22  is a view corresponding to that of  FIG. 2  of the adjusting device in the position of  FIG. 21 . 
         FIG. 23  shows in a view corresponding to that of  FIG. 1  the adjusting device according to the invention in an eleventh position. 
         FIG. 24  is a view corresponding to that of  FIG. 2  of the adjusting device in the position of  FIG. 23 . 
         FIG. 25  shows in a view corresponding to that of  FIG. 1  the adjusting device according to the invention in a twelfth position. 
         FIG. 26  is a view corresponding to that of  FIG. 2  of the adjusting device in the position of  FIG. 25 . 
         FIG. 27  shows in a view corresponding to that of  FIG. 1  the adjusting device according to the invention in a thirteenth position. 
         FIG. 28  is a view corresponding to that of  FIG. 2  of the adjusting device in the position of  FIG. 27 . 
     
    
    
     DETAILED DESCRIPTION 
     The adjusting device is part of a camshaft adjusting device that is used in connection with motor vehicles. The basic configuration of such adjusting devices is known and is therefore not explained in detail. 
     The adjusting device has a stator  1  in which a rotor  2  is arranged to be rotatably to a limited extent. The configurations of the stator and of the rotor are known in general and are therefore only discussed briefly. The stator  1  has a cylindrical casing  3  and stays  4  projecting radially inwardly away from the casing  3 . The stays  4  have the same angular spacing relative to one another. 
     The end faces  5  of the stays  4  rest a really against the cylindrical peripheral surface  6  of a base member  7  of the rotor  2 . Vanes  8  project radially from the peripheral surface  6  of the base member  7  and rest with their curved free end faces  9  areally against the cylindrical inner wall  10  of the casing  3  of the stator  1 . The vanes  8  widen in the direction toward the casing  3  of the stator  1 ; advantageously they widen continuously. However, it is also possible that the vanes  8  have a constant width across their length. Also, the width change of the vanes  8  can be non-continuous across their length. In any case, the width of the vanes  8  measured in the circumferential direction of the rotor is smaller than the spacing between the neighboring stays  4  of the stator  1 . A rotor vane  8  projects into the space between two neighboring stays  4 , respectively, and divides the area between neighboring stator stays  4  into two chambers  11  and  12 . In both chambers  11 ,  12  a pressure medium is introduced so that the corresponding one of the opposed sides of the rotor vane  8  is loaded accordingly. In this way, the rotor  2  can be rotated relative to the stator  1  in the corresponding direction. The rotor  2  can be rotated maximally such that the vanes  8  with their lateral surfaces  13 ,  14  come to rest against the facing lateral surfaces  15 ,  16  of neighboring stator stays  4 . 
     The pressure medium is introduced through bores  17 ,  18  in the base member  7  into the chambers  11  and  12 , respectively. The bores  17 ,  18  are connected by an oil distributor (not illustrated) to a valve (not illustrated) that controls the supply of the pressure medium to the chambers  11  or  12 . 
     The rotor base member  7  is fixedly connected to a camshaft (not illustrated) that is coupled in a way known in the art by an endless (continuous) drive to the crankshaft of the respective motor vehicle. 
     The stator  1  is closed at one side by an annular lid  19  that rests with its end face on the stator casing  3  and is preferably detachably connected thereto. The outer diameter of the annular lid  19  corresponds to the outer diameter of the stator casing  3 . The rotor  2  rests with its vanes  8  areally on the inner side of the annular lid  19 . The radial width of the annular lid  19  corresponds to the radial length of the vanes  8  so that the annular lid surrounds the camshaft at a spacing. 
     The base member  7  of the rotor  2  has at the side facing away from the annular lid  19  a central annular projection  20  surrounded by a locking disk  21 . It rests also with its end face on the stator casing  3 . The rotor vanes  8  are positioned so as to contact areally the inner side of the locking disk  21 . In this way, the rotor  2  is axially secured in a reliable way by the annular lid  19  and the oppositely positioned annular locking disk  21 . The locking disk  21  rests also against the cylindrical outer peripheral surface  22  of the projection  20  of the rotor base member  7 . The end face of the projection  20  and the outer side of the locking disk  21  are positioned in a common plane. 
     One rotor vane  8 ′ supports a locking bolt  23  with which the vane  8 ′ and thus the entire rotor  2  can be locked in a center position relative to the stator  1  in a way to be described in the following. The locking bolt  23  is a hollow piston in which at least one pressure spring  24  is arranged which is supported with one end on the bottom plate  25  of an axial bore  26  in the rotor vane  8 ′. The bore  26  in the rotor vane  8 ′ is closed relative to the annular lid  19  by the bottom plate  25  and is open in the direction toward the locking disk  21 . The locking disk  21  has at its inner side a locking bore  27 . The locking bolt  23  engages the locking bore  27  in the locking position under the force of the pressure spring  24 . 
     The hollow piston  23  is closed relative to the locking disk  21 . The piston surface  28  facing the locking disk  21  is planar and is loaded by a pressure medium when the locking bolt  23  is pushed back against the force of the pressure spring  24 . Since the part of the locking bolt  23  provided with the piston surface  28  has a sufficient thickness, it can receive reliably the loads that occur in the locking position. The thickness of this bolt part is advantageously greater than the depth of the locking bore  27 . 
     The locking bolt  23  is provided at its free end with a radially outwardly oriented flange  29  with which it rests against the inner wall  30  of a section  31  of the bore  26 ; the section  31  has a widened diameter relative to the rest of the bore  26 . In the illustrated embodiment, this widened section  31  extends approximately across half the length of the bore  26 . The locking bolt  23  rests against the inner wall of a section  32  of the bore  26 ; the section  32  has a reduced diameter relative to the rest of the bore  26 . 
     The annular surface  33  of the flange  29  facing the locking disk  21  is loaded in a way to be described in the following with a pressure medium that flows into an annular chamber  34 . The annular chamber  34  is delimited radially outwardly by the inner wall of the widened section  31  and radially inwardly by the locking bolt  23 . 
     The annular chamber  34  is connected to a supply groove  35  via which the pressure medium is supplied. The supply groove  35  is provided in the locking disk  21  and communicates via an axial bore  43  in the vane  8 ′ with the annular chamber  34 . As illustrated in  FIG. 1 , the supply groove  35  is U-shaped. In the locking disk  21  a further supply groove  36  is provided via which the pressure medium can reach the piston surface  28  of the locking bolt  23 . Both supply grooves  35 ,  36 , depending on the position of the vane  8 ′, are connected to the pressure chamber  11  or  12  of the stator  1 . The supply groove  35  is U-shaped and the supply groove  36  is V-shaped. 
     The other pressure chambers of the stator  1  have two throttles in the form of throttle grooves  37  and  38 , respectively. The throttle groove  37  is lunate or crescent-shaped and extends in the circumferential direction. The throttle groove  38  is approximately L-shaped. Moreover, a bore  39  opens into the chamber  12  through which pressure medium can be supplied to the chamber  12 . 
       FIGS. 1 through 14  show the adjusting device in a position in which the motor of the motor vehicle is turned off. The rotor  2  has been rotated by means of a proportional solenoid valve (not illustrated) into a rest position in which the locking recess  27  is positioned to the left of the locking bolt  23 . The rotor  2  is secured In this position until the engine is standing still. As soon as the engine has stopped, the proportional solenoid valve is switched to a currentless state. The proportional solenoid valve is switched such that the pressure line is connected to the working connector of the adjusting device. In this way, the pressure medium in the adjusting device is under pressure. Since the locking bolt  23  is not precisely aligned with the locking bore  27  of the locking disk  21 , it cannot drop into its locking position. 
     When starting the motor, the rotor  2  rotates relative to the stator  1  in a counterclockwise direction.  FIGS. 3 and 4  show the rotor  2  directly after starting the motor. In comparison to the position according to  FIGS. 1 and 2 , the rotor  2  has rotated about a fraction of a degree. The rotor vane  8 ′ closes in the position according to  FIG. 3  the supply grooves  35  and  36  completely. In the position according to  FIG. 1 , the rotor vane  8 ′ closes off only the supply groove  36  while the groove  35  is only partially closed off. In this way, there is a connection between the chamber  11  and the supply groove  35 . In the position according to  FIGS. 3 and 4 , the locking bolt  23  is not yet exactly aligned with the locking bore  27 . In order to achieve this, the rotor  2  must be rotated relative to the stator  1  farther in the counterclockwise direction. In this way, the connection between the chamber  12  and the supply groove  36  is realized ( FIGS. 5 and 6 ) so that the pressure medium upstream of the piston surface  28  of the locking bolt  23  can be routed via the supply groove  36  into the chamber  12 . The farther the rotor  2  is rotated relative to the stator  1  in the counterclockwise direction, the father the supply groove  36  is released by the rotor vane  8 ′. The supply groove  35  on the other hand remains closed by the rotor vane  8 ′ so that the pressure medium in the supply groove  35  cannot escape. In this way, the pressure medium in the annular chamber  34  also cannot escape. The annular surface  33  of the flange  29  of the locking bolt  23  is thus loaded so that the locking bolt can be retained counter to the force of the pressure spring  24  and cannot engage the locking recess  27 . 
       FIGS. 5 to 8  show two positions of the rotor  2  after it has been rotated by a fraction of an angular degree relative to the stator  1  farther in the counterclockwise direction. 
     Only when the rotor  2  has been rotated so far in the counterclockwise direction that the lateral surface  14  of the rotor vane  8 ′ releases the supply groove  35 , the pressure medium can escape from the annular chamber  34  via the supply groove  35  into the chamber  12  ( FIGS. 13 and 14 ). The locking bolt  23  is then moved by the force of the pressure spring  24  into the locking bore  27  of the locking disk  21  ( FIG. 14 ) so that the rotor  2  is locked in a central position relative to the stator  1 . In order for the locking bolt  23  to be locked reliably, the locking bore  27  is slightly elongate in the rotational direction of the rotor  2 . 
     During the described rotation of the rotor  2 , the throttle grooves  37  in the chambers  11  are not covered by the rotor vanes  8 . The throttle grooves  38 , as illustrated in  FIG. 1 , are released to some degree by the rotor vanes  8  in the initial position of the rotor  2  when the motor is switched off so that these throttle grooves  38  communicate with the chambers  11 . As soon as the rotor  2  has been rotated to such an extent that the supply groove  35  is completely covered by the rotor vane  8 ′ ( FIG. 5 ), the throttle grooves  38  are also completely covered by the remaining rotor vanes  8 . 
     The throttle grooves  37 ,  38  prevent a movement of the locking bolt  23  that is too fast in the area of the locking bore  27 . For the described movement of the rotor  2  in the counterclockwise direction, the pressure medium that is contained in the chambers  11  is supplied via the throttle grooves  37  to the throttle lines  40  that penetrate the rotor vanes  8  and the rotor base member  7  radially ( FIG. 1 ). In the vicinity of the radial outer end, a transverse bore  41  branches off the throttle lines  40  in the axial direction, respectively. In the initial position of the rotor  1  according to  FIG. 1 , the transverse bores  41  are still positioned at a spacing relative to the throttle grooves  37 . Only when the rotor vanes  8 ,  8 ′ cover the supply groove  35  and the throttle grooves  38 , the transverse bores  41  and the throttle grooves  37  will overlap, when viewed in the axial direction of the rotor, so that the pressure medium contained in the throttle grooves  37  can flow out via the transverse bores  41  and the throttle lines  40 . 
     When the rotor  2  reaches the area of the locking position, the overflow cross-section of the chambers  11  and the throttle grooves  38  is reduced so that the rotor speed is reduced. In this way, it is ensured that the locking bolt  23  reliably engages the locking bore or recess  27 . 
       FIG. 15  shows the rotor  2  in a locked position in which the locking bolt  23  engages the locking bore  27  of the locking disk  21  ( FIG. 16 ). The two supply grooves  35 ,  36  are released partially by the rotor vane  8 ′ so that a connection with the chamber  12  is provided. When in this locking position of the rotor  2  the engine of the motor vehicle is started, the proportional solenoid valve (not illustrated) is moved to a central position. In this way, both chambers  11 ,  12  on both sides of the rotor vanes  8 ,  8 ′ are filled through the bores  39 ,  42  with the pressure medium. Through the supply groove  36  the medium under pressure flows into the area upstream of the piston surface  28  of the locking bolt  23 . As long as the pressure of the spring  24  is greater than the pressure of the medium acting on the piston surface  28 , the locking bolt  23  remains in its locking position. When the pressure of the pressure medium in the chamber  12  surpasses the force of the pressure spring  24 , the locking bolt  23  is returned against the force of the pressure spring  24  into its release position ( FIGS. 25 to 28 ). When the quantity conveyed into the chamber  12  increases relative to the quantity conveyed into the chamber  11 , the rotor  2  is rotated relative to the stator  1  in the counterclockwise direction. When, on the other hand, the flow conveyed into the chamber  11  relative to the flow conveyed into the chamber  12  increases, the rotor  2  is rotated in the clockwise direction relative to the stator  2 . This rotation of the rotor  2  relative to the stator  1  for a camshaft adjustment is known in the art and is therefore not explained in more detail. By means of different pressure loading of the chambers  11 ,  12 , the rotor  2  can thus be rotated relative to the stator  1  in the desired direction for adjusting the camshaft. 
     In order for the locking bolt  23  to be secured in the retracted position, a very small rotation of the rotor  1  relative to the stator of, for example, only half an angular degree is sufficient in order to convey the pressure medium to the annular surface  33  ( FIG. 26 ) of the flange  29  of the locking bolt  23 . After the minimal rotation of the rotor  2 , by means of the rotor vane  8 ′ the supply groove  35  is opened ( FIG. 25 ) so that the pressure medium of the respective chamber  11  or  12  can flow via the supply groove  35  in the inner side of the locking disk  21  and the axial bore  43  in the rotor vane  8 ′ into the annular space  34 . In this way, the annular surface  33  of the locking bolt  23  is loaded by the pressure medium such that it remains in its pushed-back position when the rotor  2  is rotated into the desired rotational position relative to the stator  1 . The supply groove  35  is positioned symmetrically to the rotor vane  8 ′ in the locked position of the rotor  1  ( FIG. 11 ) and is covered by it in the locked position. As a result of the U-shaped configuration of the supply groove  35  and the corresponding width adjustment of the rotor vane  8 ′, the minimal rotation of the rotor  2  in the clockwise direction or counter to the clockwise direction is sufficient in order to connect the supply groove  35  with the chamber  11  or the chamber  12 . In this way, the pressure medium can reach the annular space  34  and can secure the locking bolt  23  in the described way in its retracted position against the force of the pressure spring  24 . 
     Since the supply groove  36  in the locked position of the rotor  2  is in communication with the chamber  12  and supplies this chamber during start-up of the motor with the pressure medium, the piston surface  28  at the end face of the locking bolt  23  is loaded from the beginning with the pressure medium. The adjustment is selected such that first the force of the pressure spring  24  is greater than the pressure acting on the piston surface  28  exerted by the pressure medium. In this way, the locking bolt  23  remains in the locking position immediately after starting the motor. Only when sufficient pressure has been built up, the locking bolt  23  is returned against the force of the pressure spring  24  into the release position. Since after a very minimal rotation of the rotor  2 —in the embodiment after approximately half an angular degree—the supply groove  35  is connected with the chamber  11  or  12 , the annular surface  33  of the locking bolt  23  is practically loaded directly after return of the locking bolt with sufficient pressure in order to maintain the locking bolt in the retracted position. 
       FIGS. 15 to 28  show in individual steps how, within the very minimal rotational path of the rotor  2 , the locking action is canceled by pushing back the locking bolt  23 . 
       FIGS. 15 to 28  show also that by rotation of the rotor  2  the transverse bore  41  in the rotor vanes  8  cooperates with the throttle groove  37  or  38 , depending on the rotational direction. In the illustrated embodiment, the rotor  2  is rotated in the clockwise direction relative to the stator  1  when starting the motor. As shown by means of the different positional illustrations according to  FIGS. 15 ,  17 ,  19 ,  21 ,  23 ,  25 , and  27 , first the supply groove  35  is closed by the rotor vane  8 ′ while the supply groove  36  is still in communication with the chamber  12 . When the supply groove  35  is completely closed by the rotor vane  8 ′, the pressure medium contained within the pressure chamber  34  cannot escape so that the locking bolt  23  is reliably secured in its position when it has been pushed back in the described way by pressure loading of its piston surface  28 . Upon further rotation of the rotor  2  in the clockwise direction, finally also the supply groove  36  is closed by the rotor vane  8 ′. At the same time, the lateral surface  13  of the rotor vane  8 ′ passes the control edge of the supply groove  35 ; the supply groove  35  is thus connected with the chamber  11  and the pressure medium contained therein ( FIG. 27 ). 
     Upon rotation of the rotor  2  in the clockwise direction out of the position according to  FIG. 15 , the transverse bores  41  of the remaining rotor vanes  8  are also moved correspondingly relative to the throttle grooves  37  and  38 . Firstly, the transverse bores  41  are still in communication with the throttle grooves  37  in the chambers  11  ( FIG. 15 ). A connection between the transverse bores  41  and the throttle grooves  38  is not provided in this position. When the rotor  2  is rotated farther in the clockwise direction, the transverse bores  41  are moved into a position between the two throttle grooves  37 ,  38  in which a connection between these throttle grooves and the transverse bores is not present ( FIG. 21 ). 
     Finally, the transverse bores  41  overlap the throttle bores  38  ( FIGS. 27 and 25 ) so that the pressure medium can flow via the throttle groove  38  into the chamber  11 . In this way, the rotor speed will increase again. 
     When the rotor  2  is returned from the position according to  FIG. 27  in the counterclockwise direction, the overflow cross-section between the throttle grooves  38  and the chambers  11  is reduced so that the rotor speed is also reduced. In this way, the rotor  2  reaches reliably the locking position in which the locking bolt  23  can drop into the locking bore  27 . 
     While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.