Abstract:
A device ( 10 ) for variably adjusting control times of gas exchange valves ( 9   a,    9   b ) of an internal combustion engine ( 1 ) is provided, having an external rotor ( 22 ) and an internal rotor ( 23 ) that is arranged such that it can rotate in relation to the external rotor. One of the components is drivingly connected to the crankshaft ( 2 ) and the other component is drivingly connected to the camshaft ( 6, 7 ). At least one pressure chamber ( 33 ) is provided and each of the pressure chambers ( 33 ) is divided into two counter-working pressure chambers ( 35, 36 ). One of the pressure chambers ( 35, 36 ) of each pressure chamber ( 33 ) acts as an advance chamber and the other pressure chamber ( 35, 36 ) as a trailing chamber. At least two rotation angle limiting devices ( 42, 43 ) are provided, each of the rotation angle limiting devices ( 42, 43 ) being able to assume an unlocked state and locking state. The locking state can be adjusted by supplying or withdrawing a pressure medium to and from the respective rotation angle limiting devices ( 42, 43 ).

Description:
BACKGROUND 
     The invention relates to a device for variably adjusting the control times of gas-exchange valves of an internal combustion engine with an external rotor and an internal rotor that is arranged such that it can rotate in relation to the external rotor, wherein one of the components is drivingly connected to the crankshaft and the other component is drivingly connected to a camshaft, wherein at least one pressure space is provided and each pressure space is divided into two pressure chambers working against each other, wherein one of the pressure chambers of each pressure space acts as an advancing chamber and the other pressure chamber acts as a retarding chamber, wherein by supplying pressure medium to the advancing chambers, while simultaneously withdrawing pressure medium from the retarding chambers, the rotor interacting with the camshaft is rotated relative to the rotor interacting with the crankshaft in the direction of a maximum advanced position, wherein by supplying pressure medium to the retarding chambers, while simultaneously withdrawing pressure medium from the advancing chambers, the rotor interacting with the camshaft is rotated relative to the rotor interacting with the crankshaft in the direction of a maximum retarded position, wherein at least one first pressure medium channel and one second pressure medium channel are provided by which pressure medium can be supplied to the pressure chambers or withdrawn from these chambers, wherein at least two rotational angle limiting devices are provided and wherein each rotational angle limiting device can assume an unlocked state and a locked state, wherein the locking state can be adjusted by supplying pressure medium to or withdrawing pressure medium from the respective rotational angle limiting devices. 
     In modern internal combustion engines, devices for variably adjusting the control times of gas-exchange valves are used in order to vary the phase relationship between the crankshaft and the camshaft in a defined angular region between a maximum advanced position and a maximum retarded position. For this purpose, the device is integrated into a drive train by means of which torque is transferred from the crankshaft to the camshaft. This drive train can be realized, for example, as a belt, chain, or gear train. 
     The device comprises at least two rotors that can rotate opposite each other, wherein one rotor is drivingly connected to the crankshaft and the other rotor is locked in rotation with the camshaft. The device comprises at least one pressure space that is divided by a movable element into two pressure chambers acting against each other. The movable element is in active connection with at least one of the rotors. By supplying pressure medium to the pressure chambers or by withdrawing pressure medium from the chambers, the movable element is shifted within the pressure space, by which a selective rotation of the rotors relative to each other and thus the camshaft to the crankshaft is realized. 
     The supply of pressure medium to the pressure chambers or the withdrawal of pressure medium from the pressure chambers is controlled by a control unit, usually a hydraulic directional valve (control valve). The control unit is controlled, in turn, by a controller that determines and compares the actual and desired positions of the camshaft in the internal combustion engine. If there is a difference between the two positions, a signal is transmitted to the control unit that adapts the pressure medium flows to the pressure chambers to this signal. 
     In order to guarantee the function of the device, the pressure in the pressure medium circuit of the internal combustion engine must exceed a certain value. Because the pressure medium is usually provided by the oil pump of the internal combustion engine and the provided pressure thus increases in sync with the rpm&#39;s of the internal combustion engine, below a certain rotational number, the oil pressure is still too low to change or maintain the phase position of the rotors. This can be the case, for example, during the startup phase of the internal combustion engine or during idling phases. 
     During these phases, the device would execute uncontrolled oscillations, which leads to increased noise emissions, increased wear, non-smooth running, and increased raw emissions of the internal combustion engine. In order to be able to prevent this, mechanical locking devices are provided that couple the two rotors with each other locked in rotation during the critical operating phases of the internal combustion engine, wherein this coupling can be cancelled by applying pressure medium to the locking device. In this way, for the locking position it has proven advantageous to select a phase position of the camshaft relative to the crankshaft that lies between the maximum advanced position and the maximum retarded position. 
     Such a device is known, for example, from US 2003/0121486 A1. In this embodiment, the device has a rotary piston construction, wherein an external rotor is supported such that it can rotate on an internal rotor constructed as an impeller wheel. In addition, two rotational angle limiting devices are provided, wherein a first rotational angle limiting device allows, in the locked state, an adjustment of the internal rotor relative to the external rotor in an interval between a maximum retarded position and a defined middle position (locking position). The second rotational angle limiting device allows, in the locked state, a rotation of the internal rotor relative to the external rotor in an interval between the middle position and the maximum advanced position. If both rotational angle limiting devices are in the locked state, then the phase position of the internal rotor relative to the external rotor is limited to the middle position. 
     Each of the rotational angle limiting devices is made from a spring-loaded locking pin that is arranged in a receptacle of the external rotor. Each locking pin is loaded with a force by a spring in the direction of the internal rotor. On the internal rotor, a locking groove is formed that is located opposite the locking pins in certain operating positions of the devices. In these operating positions, the pins can engage in the locking groove. In this way, each rotational angle limiting device transitions from the unlocked state into the locked state. 
     Each of the rotational angle limiting devices can transition from the locked state into the unlocked state by applying pressure medium to the locking groove. In this case, the pressure medium forces the locking pins back into their receptacles, whereby the mechanical coupling of the internal rotor to the external rotor is cancelled. 
     Applying pressure medium to the pressure chambers and the locking groove is realized by the use of a control valve, wherein on the control valve there are, among other things, two work ports that communicate with the pressure chambers and one control port that communicates with the locking groove. The fact that both rotational angle limiting devices are changed from the locked state into the unlocked state by one and the same control line is a disadvantage in the shown embodiment. In this embodiment, during an adjustment process, both rotational angle limiting devices must be unlocked, that is, loaded with pressure medium, while pressure medium is alternately supplied to the pressure chambers and withdrawn from these pressure chambers. This leads to complicated control logic of the control valve. First, a plurality of control positions are required, wherein the switch points between the control positions must be constantly redefined during the operation of the internal combustion engine due to operating-dependent variations, for example, as a result of temperature changes. In addition, the setting of the individual control states requires a higher precision of the regulator system, because the flow supplied to the valve has to lie within tightly bounded flow value intervals due to the plurality of control positions. This produces a plurality of computational and data-processing operations, whereby high requirements are placed on the control electronics. In addition, the phase accuracy of the device suffers, because even small deviations in the control loop have the effect that an undesired control state is set. 
     In addition, in this embodiment it is provided, during the startup phase of the internal combustion engine, to connect all of the pressure chambers and the locking groove to a reservoir, which leads to an inadequate supply of lubricant to the device and thus to increased wear. 
     Alternatively, pressure medium provided in another embodiment is to be supplied to one of the chambers and thus a sufficient lubricant supply is to be guaranteed. However, in this embodiment the internal rotor is clamped hydraulically opposite the external rotor. This can lead to jamming of the locking pins at the edges of the locking groove, due to which hydraulic unlocking is made more difficult or optionally even prevented. 
     SUMMARY 
     The invention is based on the objective of creating a device for the variable adjustment of the control times of gas-exchange valves of an internal combustion engine, wherein the internal rotor can be locked mechanically relative to the external rotor in a middle phase position between the maximum advanced position and the maximum retarded position. In this way, a secure locking shall be guaranteed when the internal combustion engine is stopped or at least during its startup process, undesired automatic unlocking can be avoided, the device is supplied with sufficient lubricant at all times, and a secure adjustment past the locking position can be guaranteed, wherein the individual control states of the control valve shall be easy to determine and maintain. 
     According to the invention, the objective is met in that the locking state of the first rotational angle limiting device is controlled exclusively by the pressure prevailing in at least one of the pressure chambers and that the locking state of the second rotational angle limiting device is controlled by a separate control line, wherein the control line communicates neither with the pressure medium channels nor with the pressure chambers. 
     In one embodiment of the invention, it is provided that the first rotational angle limiting device communicates via a connection line with at least one of the pressure chambers or with one of the pressure medium channels. Here it can be provided to control the locking state of the first rotational angle limiting device exclusively by the pressure prevailing in one or more advancing chambers. 
     Advantageously, when the first and second rotational angle limiting devices are locked, the internal rotor is fixed in a locking position relative to the external rotor. In this way, the second rotational angle limiting device in the locked state can limit a phase position of the rotor interacting with the camshaft relative to the rotor interacting with the crankshaft to an angular region between the maximum advanced position and the locking position. 
     In addition, it can be provided that the first rotational angle limiting device prevents the rotation of the rotor interacting with the camshaft relative to the rotor interacting with the crankshaft in the direction of the maximum advanced position when the locking position is assumed. 
     In one embodiment, it is provided that, in the locked state, the first rotational angle limiting device limits the phase position of the rotor interacting with the camshaft relative to the rotor interacting with the crankshaft to an angular region between the maximum retarded position and the locking position. 
     Advantageously, a control valve is provided that controls the supply of pressure medium to and the withdrawal of pressure medium from the pressure medium channels and the control line. 
     In this way, the control valve has two work ports, wherein the first work port communicates with the first pressure chambers and the second work port communicates with the second pressure chambers and wherein the control line communicates on the valve side exclusively with a control port formed separate to the work ports. 
     In the embodiment of the device according to the invention, a locking device is provided by which the external rotor can be coupled mechanically with the internal rotor in a locking position between a maximum advanced position and a maximum retarded position. Advantageously, two rotational angle limiting devices can be provided, wherein, in the locked state, one of the rotational angle limiting devices limits the relative phase position of the internal rotor relative to the external rotor to a region between the maximum advanced position and the locking position. In the locked state, the other rotational angle limiting device permits a phase position between the locking position and the maximum retarded position. Alternatively, this can be constructed as a locking element, wherein, in the locking position, a locking pin of the locking element engages in a recess or a blind hole adapted to the locking pin. Thus it is guaranteed that the internal rotor can be fixed mechanically relative to the external rotor in a middle phase position. 
     Each of the rotational angle limiting devices can be changed from the locked state to the unlocked state by applying pressure medium. In this way, the rotational angle limiting device that limits the relative rotation of the internal rotor to the external rotor in the locked state to a region between the maximum advanced position and the locking position communicates with a control line, wherein the other rotational angle limiting device communicates with at least one of the pressure chambers, for example, via a worm groove. Advantageously, the control line is constructed separate to the pressure medium lines and the pressure medium channels that supply the pressure chambers with pressure medium. In this way, the locking states of the rotational angle limiting devices can be adjusted independent of each other. Because one of the rotational angle limiting devices is supplied with pressure medium via at least one of the pressure chambers, the number of control positions that must be provided on the control valve can be reduced to a minimum. Thus, the number of switch points to be determined decreases, whereby the control effort during the operation of the internal combustion engine decreases significantly. In addition, the regions of the individual control positions of the control valve constructed as a proportional valve can be increased, whereby, in turn, the control effect decreases and the functional security is increased. 
     Through the separate control of one of the rotational angle limiting devices by a control line, it is further possible to stop the device during the shutdown process in a defined interval that contains the locking position. During the shutdown process or alternatively during the restart of the internal combustion engine, the internal rotor is led automatically into the locking position, wherein the mechanical connection between the rotors is created by the rotational angle limiting devices. 
     Because the control line is constructed independent of the pressure medium lines supplying the device, during the startup phase both rotational angle limiting devices can be connected to the tank, wherein a pressure medium channel communicates neither with the tank nor with the pump. Thus, automatic unlocking of the device can be stopped. Simultaneously, the leakage oil entering the pressure medium lines via the control valve can be suctioned through a small, oscillating movement of the internal rotor relative to the external rotor, whereby a sufficient supply of lubricant to the device is guaranteed even during the startup phase. The small, oscillating movement of the internal rotor relative to the external rotor results from the alternating moments acting on the camshaft in combination with a small locking play of the rotational angle limiting devices. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Additional features of the invention emerge from the following description and from the drawings in which an embodiment of the invention is shown simplified. Shown are: 
         FIG. 1  only very schematically an internal combustion engine, 
         FIG. 2   a  a cross-sectional view through an embodiment according to the invention of a device for changing the control times of gas-exchange valves of an internal combustion engine including an attached hydraulic circuit, 
         FIG. 2   b  a longitudinal section view through the device from  FIG. 2   a  along the line IIb-IIb, 
         FIG. 2   c  a cross-sectional view through the device from  FIG. 2   b  along the line IIc-IIc, 
         FIG. 3  a first control logic diagram of a control valve of the device according to the invention, 
         FIG. 4  a second control logic diagram of a control valve of the device according to the invention, 
         FIG. 5  a perspective view of a control valve for controlling the device according to the invention, 
         FIG. 6  a partial longitudinal section view through the control valve from  FIG. 5 , 
         FIGS. 6   a - 6   g  longitudinal section views through the essential parts of the control valve from  FIG. 6  in its different control positions. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In  FIG. 1 , an internal combustion engine  1  is shown schematically, wherein a piston  3  connected to a crankshaft  2  is shown in a cylinder  4 . In the shown embodiment, the crankshaft  2  is connected to an intake camshaft  6  and/or exhaust camshaft  7  by a traction mechanism drive  5 , wherein a first and a second device  10  can provide for a relative rotation between the crankshaft  2  and the camshafts  6 ,  7 . The cams  8  of the camshafts  6 ,  7  activate one or more intake gas-exchange valves  9   a  or one or more exhaust gas-exchange valves  9   b . It also can be provided to equip only one of the camshafts  6 ,  7  with a device  10  or to provide only one camshaft  6 ,  7  that is provided with a device  10 . 
       FIGS. 2   a  and  2   b  show an embodiment of a device  10  according to the invention in cross section and in longitudinal section, respectively. The device  10  has an external rotor  22 , an internal rotor  23 , and two side covers  24 ,  25 . The internal rotor  23  is constructed in the form of an impeller wheel and has an essentially cylindrical hub element  26  from whose outer cylindrical lateral surface extend five vanes  27  outwardly in the radial direction in the shown embodiment. In this way, the vanes  27  can be formed integrally with the hub element  26 . Alternatively, the vanes  27 , as shown in  FIG. 2   a , can be constructed separately and can be arranged in axial vane grooves  28  formed on the hub element  26 , wherein the vanes  27  are loaded with a force radially outwardly by not-shown spring elements arranged between the groove bases of the vane grooves  28  and the vanes  27 . 
     Starting from an outer peripheral wall  29  of the external rotor  22 , several projections  30  extend radially inward. In the shown embodiment, the projections  30  are formed integrally with the peripheral wall  29 . Also conceivable, however, are embodiments in which instead of the projections  30  there are vanes that are attached to the peripheral wall  29  and extend radially inwardly. The external rotor  22  is supported on the internal rotor such that it can rotate relative to the internal rotor  23  by radially inwardly lying peripheral walls of the projections  30 . 
     On an outer lateral surface of the peripheral wall  29  there is a chain wheel  21  by which torque can be transmitted from the crankshaft  2  to the external rotor  22  by a not-shown chain drive. The chain wheel  21  can be constructed as a separate component and locked in rotation with the internal rotor  23  or can be constructed integrally with this internal rotor. Alternatively, a belt drive or gear drive can also be provided. 
     Each of the side covers  24 ,  25  is arranged on one of the axial side surfaces of the external rotor  22  and locked in rotation on this external rotor. In each of the projections  30  there is an axial opening  31  for this purpose, wherein each axial opening  31  is penetrated by an attachment element  32 , for example, a bolt or a screw that is used for rotational fixing of the side covers  24 ,  25  on the external rotor  22 . 
     Within the device  10 , between every two projections  30  adjacent in the peripheral direction there is a pressure space  33  that is bounded in the peripheral direction by opposing, essentially radial boundary walls  34  of adjacent projections  30 , in the axial direction by the side covers  24 ,  25 , radially inward by the hub element  26 , and radially outward by the peripheral wall  29 . A vane  27  projects into each of the pressure spaces  33 , wherein the vanes  27  are constructed such that these vanes contact both the side walls  24 ,  25  and also the peripheral wall  29 . Each vane  27  thus divides the respective pressure space  33  into two pressure chambers  35 ,  36  acting against each other. 
     The external rotor  22  is arranged in a defined angular region so that it can rotate relative to the internal rotor  23 . The angular region is bounded in one rotational direction of the external rotor  22  such that each vane  27  comes to lie against a boundary wall  34  of the pressure space  33  formed as an advance stop  34   a . Analogously, the angular range in the other rotational direction is bounded such that each vane  27  comes to lie against the other boundary wall  34  of the pressure space  33  that acts as a retard stop  34   b . Alternatively, a rotational angle limiting device can be provided that limits the rotational angle region of the external rotor  22  relative to the internal rotor  23 . 
     By pressurizing one group of pressure chambers  35 ,  36  and depressurizing the other group, the phase position of the external rotor  22  relative to the internal rotor  23  can be varied. By pressurizing both groups of pressure chambers  35 ,  36 , the phase position of the two rotors  22 ,  23  can be held constant relative to each other. Alternatively, it can be provided to pressurize none of the pressure chambers  35 ,  36  with pressure medium during phases of constant phase position. The lubricating oil of the internal combustion engine  1  is typically used as the hydraulic pressure medium. 
     For supplying pressure medium to or withdrawing pressure medium from the pressure chambers  35 ,  36 , a pressure medium system is provided that comprises a not-shown pressure medium pump, a similarly not-shown tank, a control valve  37 , and several pressure medium lines  38   a ,  38   b ,  38   p . Pressure medium fed from the pressure medium pump is supplied to the control valve  38  via the third pressure medium line  38   p . According to the control state of the control valve  37 , the third pressure medium line  38   p  is connected to the first pressure medium line  38   a , the second pressure medium line  38   b , or to both or none of the pressure medium lines  38   a ,  38   b.    
     The internal rotor  23  is formed with two groups of pressure medium channels  39   a ,  39   b , wherein each pressure medium channel  39   a ,  39   b  extends from an inner lateral surface of a receptacle  40  of the internal rotor  23  to one of the pressure chambers  35 ,  36 . The first pressure medium line  38   a  communicates with the first pressure medium channels  39   a . The second pressure medium line  38   b  communicates with the second pressure medium channels  39   b . For this purpose, for example, a pressure medium distributor can be provided that is arranged in a receptacle  40 . In one alternative embodiment, the control valve  37  is constructed as a central valve and is arranged in the receptacle  40 , wherein, in this case, the control valve  37  connects the third pressure medium line  38   p  directly to the pressure medium channels  39   a ,  39   b.    
     In order to shift the control times (opening and closing times) of the gas-exchange valves  9   a ,  9   b  in the advanced direction, the pressure medium supplied to the control valve  37  via the third pressure medium line  38   p  is led to the group of first pressure chambers  35  via the first pressure medium channels  39   a  and optionally the first pressure medium line  38   a . Simultaneously, pressure medium is led out of the group of second pressure chambers  36  via the second pressure medium channels  39   b  and optionally the second pressure medium line  38   b  to the control valve  37  and is ejected into the tank. Therefore, the vanes  27  are shifted in the direction of the advance stop  34   a , whereby a rotational movement of the internal rotor  23  relative to the external rotor  22  is achieved in the rotational direction of the device  10 . 
     In order to shift the control times of the gas-exchange valves  9   a ,  9   b  in the retarded position, the pressure medium supplied to the control valve  37  via the third pressure medium line  38   p  is led via the second pressure medium channels  39   b  and optionally the second pressure medium line  38   b  to the group of second pressure chambers  36 . Simultaneously, pressure medium is led out of the group of first pressure chambers  35  via the first pressure medium channels  39   a  and optionally the first pressure medium line  38   a  to the control valve  37  and is ejected into the tank. In this way, the vanes  27  are shifted in the direction of the retard stop  34   a , whereby a rotational movement of the internal rotor  23  relative to the external rotor  22  is achieved against the rotational direction of the device  10 . 
     In order to maintain the control times constant, the pressure medium supply to all of the pressure chambers  35 ,  36  is either stopped or permitted. Therefore, the vanes  27  are clamped hydraulically within each pressure space  33  and thus a rotational movement of the internal rotor  23  relative to the external rotor  22  is prevented. 
     During the startup of the internal combustion engine  1  or during idling phases, the pressure medium supply to the device  10  may not be sufficient, in order to guarantee the hydraulic clamping of the vanes  27  within the pressure spaces  33 . In order to prevent uncontrolled oscillation of the internal rotor  23  relative to the external rotor  22 , there is a locking mechanism  41  that creates a mechanical connection between the two rotors  22 ,  23 . For this, a locking pin is arranged in one of the rotors  22 ,  23 , while a connecting passage is formed in the other rotor  22 ,  23 . If the internal rotor  23  is located in a defined phase position (locking position) relative to the external rotor  22 , then the locking pin can engage in the connecting passage and thus a mechanical, rotationally locked connection can be created between the two rotors  22 ,  23 . 
     It has proven advantageous to select the locking position such that the vanes  27  in the locked state of the device  10  are located in a position between the advance stop  34   a  and the retard stop  34   b . Such a locking mechanism  41  is shown in  FIG. 2   c . These are made from a first and a second rotational angle limiting device  42 ,  43 . In the shown embodiment, each of the rotational angle limiting devices  42 ,  43  is made from an axially displaceable locking pin  44 , wherein each of the locking pins  44  is held in a borehole of the internal rotor  23 . In addition, in the first side wall  24  there are two connecting passages  45  in the form of grooves running in the peripheral direction. These are indicated in  FIG. 2   c  in the form of broken lines. Each of the locking pins  44  is loaded with a force in the direction of the first side cover  24  by a spring element  46 . If the internal rotor  23  assumes a position relative to the external rotor  22  in which a locking pin  44  is opposite the associated connecting passage  45  in the axial direction, then this pin is forced into the connecting passage  45  and the respective rotational angle limiting device  42 ,  43  changes from an unlocked state into a locked state. In this way, the connecting passage  45  of the first rotational angle limiting device  42  is constructed such that the phase position of the internal rotor  23  relative to the external rotor  22  is limited, when the first rotational angle limiting device  42  is locked, to a region between a maximum retarded position and the locking position. If the internal rotor  23  is located relative to the external rotor  22  in the locking position, then the locking pin  44  of the first rotational angle limiting device  42  contacts a stop formed in the peripheral direction by the connecting passage  45 , whereby further adjustment in the direction of more advanced control times is prevented. 
     Analogously, the connecting passage  45  of the second rotational angle limiting device  43  is designed such that for a locked section rotational angle limiting device  43 , the phase position of the internal rotor  23  relative to the external rotor  22  is limited to a region between a maximum advanced position and the locking position. 
     In order to move the rotational angle limiting devices  42 ,  43  from the locked state into the unlocked state, it is provided that the respective connecting passage  45  is loaded with pressure medium. In this way, the respective locking pin  44  is forced back against the force of the spring element  46  into the borehole and thus the rotational angle limiting is cancelled. 
     In the shown embodiment, it is provided to supply the connecting passage of the first rotational angle limiting device  42  with pressure medium via one of the first pressure chambers  35  and a connection line  47 , wherein this first rotational angle limiting device prevents, in the locked state, the rotation of the internal rotor  23  relative to the external rotor  22  in the advanced direction at the locking position. The connecting passage  45  of the second rotational angle limiting device  43  can be loaded with pressure medium by the control line  48  and the channel  49 . In this way it is provided that the control valve  37  regulates both the pressure medium flows to and from the first and second pressure chambers  35 ,  36  and also to and from the control line  48 . 
     Such a control valve  37  is shown in  FIGS. 5 and 6 . The control valve  37  is made from an actuator  50  and a hydraulic section  51 . The hydraulic section  51  is made from a valve housing  52  of an intermediate sleeve  53  and a control piston  54 . On the valve housing  52  there is a first work port A, a second work port B, an inflow port P, a control port S, and an axial and a radial outflow port T. The first work port A communicates with the first pressure medium line  38   a . The second work port B communicates with the second pressure medium line  38   b . The inflow port P communicates with the third pressure medium line  38   p . The control port S communicates with the control line  48 . Pressure medium can flow into a not-shown tank via the outflow ports T. 
     The intermediate sleeve  53  is arranged within the valve housing  52  fixed in position relative to this housing. On its outer lateral surface there is a work groove  56 , a control groove  57 , five work openings  56   a - e , and three control openings  57   a - c . The work groove  56  and the control groove  57  extend in the peripheral direction of the intermediate sleeve  53  each in a defined angle interval, wherein the two grooves  56 ,  57  are separated from each other hydraulically. The work ports A, B and the inflow port P are formed as radial openings in the valve housing  52 , wherein the radial openings are formed exclusively in the region of the angular segment assumed by the work groove  56 . Similarly, the control port S is realized by one or more radial openings that are formed exclusively in the region of the angular segment assumed by the control groove  57 . 
     The work openings  56   a - e  communicate on one side with the interior of the intermediate sleeve  53  and on the other side with the first work port A (first work opening  56   a ), the inflow port P (second work opening  56   b ), the work groove  56  (third and fourth work opening  56   c, d ) or the radial tank port T (fifth work opening  56   e ). The work groove  56  also communicates with the second work port B. Furthermore, it can be provided to form additional grooves in the outer lateral surface of the intermediate sleeve  53  that connects the first, the second, or the fifth work opening  56   a, b, e  to the respective port A, P, T. 
     The control openings  57   a - c  communicate on one side with the interior of the intermediate sleeve  53  and on the other side with the control groove  57  that communicates, in turn, with the control port S. 
     The control piston  54  has an essentially hollow cylindrical construction and is arranged within the intermediate sleeve  53 , wherein this piston can be moved by the actuator  50  against the force of a spring  55  in the axial direction relative to the intermediate sleeve  53  and the valve housing  52 . The control piston  54  has three annular grooves  58   a - c  and first and second openings  59   a, b.    
     The actuator  50  can be formed, for example, as an electrical actuator, wherein a magnetized armature is arranged within a coil. By exciting the coil, the armature can be shifted in the axial direction. This movement can be transmitted to the control piston  54  by a tappet rod  50   a.    
     Through axial displacement of the control piston  54  within the intermediate sleeve  53 , the work ports A, B and the control port S can be connected selectively to the inflow port P, the outflow port T, or none of the two. 
     In  FIG. 3 , control logic of the control valve  37  shown in  FIG. 5  or  FIG. 6  is shown. Here, the connections of the first work port A, the second work port B, and the control port S to the pressure medium pump or the tank are shown as a function of the excitation of the actuator  50  or the axial displacement D of the control piston  54  within the intermediate sleeve  53 . The control logic can be divided into seven control positions. In this way, the control valve  37  passes through, with increasing excitation of the actuator  50  (axial displacement of the control piston  54 ), the control positions in the sequence: startup position S 1 , unlocked position S 2 , trailing position S 3 , first intermediate position S 4 , holding position S 5 , second intermediate position S 6 , and leading position S 7 . The positions of the control piston  54  relative to the valve housing  52  or the intermediate sleeve  53  in the various control positions S 1 -S 7  are shown in  FIGS. 6   a - g.    
     In the startup position S 1  ( FIG. 6   a ) that the control valve  37  assumes when the actuator  50  is not activated, the first work port A (via the first work opening  56   a ) and the control port S (via the first control opening  57   a ) are connected to the axial outflow port T. Thus, pressure medium is discharged from the first pressure chambers  35  and thus from the first rotational angle limiting device  42  and from the second rotational angle limiting device  43  to the tank. The second work port B is closed (connected neither to the inflow port nor to the outflow port P, T). 
     When transitioning from the startup position S 1  to an unlocked position S 2  ( FIG. 6   b ), the control port S (via the second work opening  56   b , the first annular groove  58   a , the first opening  59   a , the interior of the control piston  54 , the second opening  59   b , the third annular groove  58   c , the second control opening  57   b , and the control groove  57 ) is connected to the pump. The first work port A further communicates with the axial outflow port T, while the second work port B continues to be closed (analogous to  FIG. 6   a ). 
     In the subsequent trailing position S 3  ( FIG. 6   c ), the second work port B (via the second work opening  56   b , the second annular groove  58   b , the third work opening  56   c , and the work groove  56 ), as well as the control port S is connected to the inflow port P (analogous to  FIG. 6   b ), wherein the first work port A is connected to the axial outflow port T (analogous to  FIG. 6   a ). 
     In the first intermediate position S 4  ( FIG. 6   d ), the first work port A is closed, while the second work port B and the control port S are connected to the inflow port P (analogous to  FIG. 6   c ). 
     In the holding position S 5  ( FIG. 6   e ), both work ports A, B and the control port S are closed. 
     In the second intermediate position S 6  ( FIG. 6   f ), the first work port A (via the second work opening  56   b , the first annular groove  58   a , and the first work opening  56   a ) is connected to the inflow port P, while the second work port B and the control port S are closed (analogous to  FIG. 6   e ). 
     In the subsequent leading position S 7  ( FIG. 6   g ), the second work port B, as well as the control port S (via the fourth work opening  56   d  or the third control opening  57   c , the interior of the intermediate sleeve  53 , and the fifth work opening  56   e ), is connected to the radial outflow port T and the first work port A is connected to the inflow port P (analogous to  FIG. 6   f ). 
     During the startup phase of the internal combustion engine  1 , the control valve  37  is located in the startup position S 1 . In this phase, the hydraulic clamping of the vanes  27  within the pressure spaces  33  is generally not guaranteed due to a system pressure that is too low. For this reason, the internal rotor  23  will carry out movements oscillating opposite the external rotor  22  in the peripheral direction. These oscillations are caused by the alternating moments acting on the camshafts  6 ,  7 , wherein the oscillations themselves appear in the locked state of the device  10 . In this way, their amplitude is defined by the locking play. The oscillations result in a pumping effect, whereby residual oil present in the pressure medium channels  39   a, b  or the pressure medium lines  38   a, b  can be fed into the pressure chambers  35 ,  36 . In this way, pressure values that are sufficient to move the rotational angle limiting devices  42 ,  43  into the unlocked state can be achieved within the device  10 . 
     Through the connection of the first work port A and the control port S to the tank, this is prevented. The first pressure chambers  35 , the corresponding pressure medium channels  39   a , the first pressure medium line  38   a , and the control line  48  are emptied and thus a pressure buildup, and with it the undesired automatic unlocking during the startup phase, in the connecting passages  45  of the rotational angle limiting devices  42 ,  43  is prevented. 
     Because the second work port B is closed in the startup position S 1 , the second pressure chambers  36  are not charged with pressure medium. Therefore, it is prevented that the locking pin  44  of the second rotational angle limiting device  43  is forced against the end of the connecting receptacle  45 , which could lead to jamming. On the other hand, it is prevented that the pressure medium in the second pressure medium channels  39   b  can flow to the tank. Thus, it is guaranteed that through the oscillations of the vanes  27 , small quantities of pressure medium are fed into the second pressure chambers  36 , whereby the device  10  is supplied with sufficient lubricant. 
     After a defined time span has elapsed after which the startup process has completely ended or when a sufficient pressure level is detected in the lubricant circuit of the internal combustion engine  1  and the motor controller forces a phase change, the device  10  transitions into a regulated state until the pressure in the lubricant circuit again falls below a given level. For this purpose, the actuator  50  of the control valve  37  is excited such that this valve is led via the unlocked position S 2  into the control positions S 3  to S 7  and is regulated, according to the setting of the phase angle, by the motor controller into one of these control positions S 3 -S 7 . 
     While the control valve  37  assumes the unlocked position S 2 , in contrast to the startup position S 1 , the control port S is charged with pressure medium and thus the second rotational angle limiting device  43  transitions into the unlocked state. In this way, none of the pressure chambers  35 ,  36  are loaded with pressure, whereby jamming of the locking pin  44  of the second rotational angle limiting device  43  in its connecting passage  45  is prevented. 
     As a function of the current desired or actual values of the phase position, in the locked state of the device  10 , the control valve  37  assumes the control positions S 3 -S 7 . If a displacement of the phase position in the direction of more retarded inlet times is forced by the motor controller, then the control valve  37  is activated such that this assumes the trailing position S 3 . In this position, the first pressure chambers  35  are connected to the tank and the second pressure chambers  36  are connected to the pump. Simultaneously, pressure medium is led to the connecting passage  45  of the second rotational angle limiting device  43 . The locking pin  44  of the second rotational angle limiting device  43  is held in the unlocked state, while, for simultaneous emptying of the first pressure chambers  35 , the pressure medium loading of the second pressure chambers  36  leads to rotation of the internal rotor  23  relative to the external rotor  22  against the rotational direction of the device  10 . If the motor controller forces the phase position of the internal rotor  23  relative to the external rotor  22  to be held, then this control valve  37  is moved into the holding position S 5 . In this position, pressure medium is not exchanged between the pressure chambers  35 ,  36  and the connecting passage  45  of the second rotational angle limiting device  43  to the tank or the pressure medium pump. The vanes  27  are clamped hydraulically in the pressure space  33  and the rotational angle limiting devices  42 ,  43  are held in the unlocked position. 
     If the motor controller forces more advanced control times, then the control valve  37  is brought into the leading position S 7 . In this control position, pressure medium is fed to the first pressure chambers  35 , while pressure medium is discharged to the tank both from the connecting passage  45  of the second rotational angle limiting device  43  and also from the second pressure chambers  36 . Consequently, a relative rotation of the internal rotor  23  relative to the external rotor  22  is caused in the rotational direction of the device  10 . In addition, the locking pin  44  of the second rotational angle limiting device  43  can engage in the corresponding connecting passage  45  when these stand opposite each other. 
     In the intermediate positions S 4  and S 6 , one group of pressure chambers  35 ,  36  is loaded with pressure medium, while there is no exchange of pressure medium between the other group of pressure chambers  35 ,  36  and the pump and the tank. In this way it is achieved that during the assumption or exiting of the holding position S 5 , the hydraulic clamping of the vanes  27  within the pressure spaces  33  is maintained. 
     During the stop phase of the internal combustion engine  1 , the control valve  37  moves into the leading position S 7  and is held in this position for a defined time span past its standstill. Therefore, pressure medium is fed to the first pressure chambers  35 , while pressure medium can flow out of the second pressure chambers  36  to the tank. This causes a relative rotation of the internal rotor  23  to the external rotor  22 , wherein the internal rotor  23  is led into a position between the locking position and the maximum advanced position. Simultaneously, the control port S and thus the connecting passage  45  of the second rotational angle limiting device  43  are connected to the tank, whereby the second rotational angle limiting device  43  is moved into the locked state. In this way it is guaranteed that the internal rotor  23  moves into a position between the locking position and the maximum advanced position and is then held in this position during the entire stop process and the operating pause of the internal combustion engine  1 . 
     In the last phase of the motor stop in which the device  10  is no longer supplied with sufficient pressure medium, the internal rotor  23  is rotated relative to the external rotor  22  in the direction of the maximum retarded position due to the drag moments acting on the camshafts  6 ,  7 . This movement is stopped by the locked second rotational angle limiting device  43  at the locking position. Due to the lack of system pressure, the first rotational angle limiting device  42  in this position is similarly moved into the locked state, whereby a mechanical fixing of the internal rotor  22  relative to the external rotor  23  is established in the locking position. Alternatively, this process can take place during the startup phase of the internal combustion engine  1  in which the control valve  37  assumes the startup position S 1 . In this position, the first pressure chambers  35  and the connecting passage  45  of the first rotational angle limiting device  42  connected to these chambers are connected to the tank. The internal rotor  22  is forced into the locking position due to the drag moments acting on the camshaft  6 ,  7  in which the first rotational angle limiting device  42  can transition into the locked state. 
     During the regulated operation of the device  10  (control states S 3 -S 7 ), due to the control logic shown in  FIG. 3  it is guaranteed that when one group of pressure chambers  35 ,  36  is pressurized, the associated rotational angle limiting device  42 ,  43  is located in the unlocked state. Thus, a secure adjustment of the device  10  past the locking position is guaranteed. 
     Through the separate control of the rotational angle limiting devices  42 ,  43 , only a small number of switch points exists in the control logic that are stored in the motor controller or must be determined by this controller. Simultaneously, the regions of the individual control positions S 1 -S 7  increase, whereby the regulation of the control valve  37  is simplified considerably and the error susceptibility is reduced. 
       FIG. 4  shows alternative control logic to the control logic shown in  FIG. 3 , wherein the sole difference consists in that the sequence of control positions S 1 -S 7  is transposed. In this construction, the startup position S 1  is assumed for a maximally activated actuator  50 , while the leading position S 7  is assumed for a non-activated actuator  50 . 
     REFERENCE SYMBOLS 
     
         
           1  Internal combustion engine 
           2  Crankshaft 
           3  Piston 
           4  Cylinder 
           5  Traction mechanism drive 
           6  Intake camshaft 
           7  Exhaust camshaft 
           8  Cams 
           9   a  Intake gas-exchange valve 
           9   b  Exhaust gas-exchange valve 
           10  Device 
           21  Chain wheel 
           22  External rotor 
           23  Internal rotor 
           24  Side cover 
           35  Side cover 
           26  Hub element 
           27  Vane 
           28  Vane grooves 
           29  Peripheral wall 
           30  Projection 
           31  Axial opening 
           32  Attachment element 
           33  Pressure space 
           34  Boundary wall 
           34   a  Advance stop 
           34   b  Retard stop 
           35  First pressure chamber 
           36  Second pressure chamber 
           37  Control valve 
           38   b  First pressure medium line 
           38   a  Second pressure medium line 
           38   p  Third pressure medium line 
           39   b  First pressure medium channel 
           39   a  Second pressure medium channel 
           40  Receptacle 
           41  Locking mechanism 
           42  Rotational angle limiting device 
           43  Rotational angle limiting device 
           44  Locking pin 
           45  Connecting passage 
           46  Spring element 
           47  Connecting line 
           48  Control line 
           49  Channel 
           50  Actuator 
           50   a  Tappet rod 
           51  Hydraulic section 
           52  Valve housing 
           53  Intermediate sleeve 
           54  Control piston 
           55  Spring 
           56  Work groove 
           56   a  First work opening 
           56   b  Second work opening 
           56   c  Third work opening 
           56   d  Fourth work opening 
           56   e  Fifth work opening 
           57  Control groove 
           57   a  First control opening 
           57   b  Second control opening 
           57   c  Third control opening 
           58   a  First annular groove 
           58   b  Second annular groove 
           58   c  Third annular groove 
           59   a  First opening 
           59   b  Second opening 
         A First work port 
         B Second work port 
         P Inflow port 
         T Outflow port 
         S Control port 
         D Displacement 
         S 1  Startup position 
         S 2  Unlocked position 
         S 3  Trailing position 
         S 4  First intermediate position 
         S 5  Holding position 
         S 6  Second intermediate position 
         S 7  Leading position