Abstract:
A camshaft adjusting device including a vane cell adjuster with a stator which can be connected to a crankshaft of an internal combustion engine and with a rotor which is rotatably mounted in the stator and can be connected to a camshaft. The camshaft adjusting device also includes a central locking device for locking the rotor in a central locking position relative to the stator. In one or more of the vanes together: at least two pressure medium lines are provided, each of which fluidically connects two working chambers with different working directions to each other. Non-return valves with different working directions are provided in each pressure medium line, each non-return valve allowing a flow of the pressure medium between the working chambers in one direction and preventing the flow in the respective other direction depending on the rotational direction of the rotor relative to the stator. A first switchable valve device is provided in the respective other vanes which are not provided with non-return valves, the valve device allowing a flow of the pressure medium between the working chambers with different working directions in one switch position.

Description:
[0001]    The present invention relates to a camshaft adjusting device. 
       BACKGROUND 
       [0002]    Camshaft adjusting devices are generally used in valve train assemblies of internal combustion engines to vary the valve opening and closing times, whereby the consumption values of the internal combustion engine and the operating behavior in general may be improved. 
         [0003]    One specific embodiment of the camshaft adjusting device, which has been proven and tested in practice, includes a vane adjuster having a stator and a rotor, which delimit an annular space, which is divided into multiple working chambers by projections and vanes. A pressure medium may be optionally applied to the working chambers, which is supplied to the working chambers on one side of the vanes of the rotor from a pressure medium reservoir in a pressure medium circuit via a pressure medium pump, and which is fed back into the pressure medium reservoir from the working chambers on the particular other side of the vanes. The working chambers whose volume is increased have an operating direction which is opposite to the operating direction of the working chambers whose volume is reduced. As a result, the operating direction means that an application of pressure medium to the particular group of working chambers induces a rotation of the rotor relative to the stator either in the clockwise or the counterclockwise direction. The control of the pressure medium flow, and thus the adjusting movement of the camshaft adjusting device, takes place, e.g., with the aid of a central valve having a complex structure of flow-through openings and control edges, and a valve body, which is movable within the central valve and which closes or unblocks the flow-through openings as a function of its position. 
         [0004]    One problem with a camshaft adjusting device of this type is that the camshaft adjusting device is not yet completely filled with pressure medium in a start phase or may even have been emptied, so that, due to the alternating torques applied by the camshaft, the rotor may execute uncontrolled movements relative to the stator, which may result in increased wear and an undesirable noise development. To avoid this problem, it is known to provide a locking device between the rotor and the stator, which locks the rotor when the internal combustion engine is turned off in a rotation angle position with respect to the stator which is favorable for startup. In exceptional cases, for example if the internal combustion engine is stalled, it is possible, however, that the locking device does not properly lock the rotor, and the camshaft adjuster must be operated with an unlocked rotor in the subsequent start phase. However, since some internal combustion engines have a very poor start behavior if the rotor is not locked in the central position, the rotor must then be automatically rotated into the central locking position and locked in the start phase. 
         [0005]    Such an automatic rotation and locking of the rotor with respect to the stator are known, for example, from DE 10 2008 011 915 A1 and from DE 10 2008 011 916 A1. Both locking devices described therein include a plurality of spring-loaded locking pins, which successively lock into locking gates provided on the sealing cover or the stator when the rotor rotates and which each permit a rotation of the rotor in the direction of the central locking position before reaching the central locking position while blocking a rotation of the rotor in the opposite direction. After the internal combustion engine has warmed up and/or the camshaft adjuster has been completely filled with pressure medium, the locking pins are forced out of the locking gates, actuated by the pressure medium, so that the rotor is subsequently able to properly rotate with respect to the stator to adjust the rotation angle position of the camshaft. 
         [0006]    One disadvantage of this approach is that the locking of the rotor may be accomplished only with the aid of multiple successively locking locking pins, which results in higher costs. In addition, the locking procedure requires that the locking pins lock successively in a fail-safe manner. If one of the locking pins does not lock, the locking procedure may be interrupted, since the rotor is thus not locked in the intermediate position on one side and is able to rotate back. 
       SUMMARY OF THE INVENTION 
       [0007]    It is an object of the present invention to provide a camshaft adjuster which has a fail-safe and cost-effective central lock of the rotor. 
         [0008]    The present invention provides at least two pressure medium lines are provided together in one or multiple of the vanes, which fluidically connect two working chambers of different operating directions to each other, check valves of different operating directions being provided in each of the pressure medium lines, which facilitate an overflow of the pressure medium between the working chambers in one direction and prevent it in the other direction, as a function of the rotation direction of the rotor with respect to the stator, and a first switchable valve device, which facilitates an overflow of the pressure medium between the working chambers of different operating directions in one switching position, being provided in the particular other vanes, in which no check valve is provided. 
         [0009]    Due to the proposed approach, the rotor may be rotated out of the stop positions into the central locking position solely by utilizing the active camshaft alternating torques, since the check valve device deliberately facilitates only an overflow of the pressure medium. As a result, the rotor rotates jerkily from the direction of the stop positions in the direction of the central locking position during the active camshaft alternating torques until it locks in the central locking position. The camshaft alternating torques are deliberately used to adjust the rotor only in one direction, since a flow of the pressure medium back through the check valve device is simultaneously prevented. Since, according to the present invention, a first switchable valve device, which facilitates the overflow of the pressure medium, is provided in the other vanes, in which no check valve is provided, the automatic adjusting movement is not blocked by the pressure medium present in the working chambers. 
         [0010]    It is furthermore proposed that a second switchable valve device is provided in each of the vanes with the check valves, with the aid of which the flow of the pressure medium to the check valves is facilitated in a first switching position and prevented in a second switching position. Due to the proposed approach, the overflow of the pressure medium may be actively prevented, so that the camshaft adjusting device may be operated with the desired accuracy during the normal, actively controlled adjustment procedure. 
         [0011]    It is furthermore proposed that a third switchable valve device is provided, which, in a first switching position, fluidically connects the working chamber into which the pressure medium flows via the check valve to a working chamber of the same operating direction which abuts another vane with a check valve situated therein and fluidically separates it in a second switching position. Since an automatic adjusting movement from the two “advance” and “retard” stop directions should be possible, two check valves of a different operating direction must be provided. If these check valves are provided in two different vanes, an overflow of the pressure medium only between two working chambers is provided with the aid of one check valve provided in the vane, while the overflow of the pressure medium between the working chambers is not possible via a vane which includes an oppositely acting check valve. Due to the proposed approach, in one switching position of the third valve device, the pressure medium is able to flow out of the working chamber having the reducing volume, from which the pressure medium is unable to overflow via the check valve and, via the third switchable valve device, into the working chamber from which the pressure medium is further able to overflow into the working chamber of the opposite operating direction on the other side of the vane via the check valve. In a second switching position of the third valve device, the working chamber is then deliberately separated from the other working chamber, so that the rotor is able to be supported on the stator via the pressure medium present in the working chamber during the automatic adjusting movement, and the automatic adjusting movement in this position of the third valve device is possible only in one rotation direction of the rotor. 
         [0012]    It is furthermore proposed that a pressure medium may be applied jointly to the first, second and third valve devices with the aid of a multi-way switching valve. Due to the proposed approach, all three valve devices together may be transferred to a switching position, in which the pressure medium flow between the working chambers of different operating directions is prevented, and thus the automatic adjusting movement made possible according to the present invention is practically deactivated, and the camshaft adjusting device may be operated in the conventional way solely by the active application of pressure medium to the working chambers. 
         [0013]    In particular, it is proposed that the working chambers into which the pressure medium flows via the check valves are fluidically connected to a pressure medium line which connects at least two working chambers of the same operating direction via one pressure medium line and to the third switchable valve device via another pressure medium line. As a result, two pressure medium lines, which are separated from each other, empty into the working chamber. One of the pressure medium lines then connects the working chamber to the pressure medium line which permanently connects the working chambers of the same operating direction, e.g., a ring line, for the purpose of actively applying pressure medium to the working chamber during the controlled adjusting movement. The other pressure medium line then connects the working chamber to the working chamber of the same operating direction at the vane which includes the check valve of the opposite operating direction and may be interrupted or opened by the third valve device, whereby the pressure medium flow described above for supporting the rotor or for the overflow of the pressure medium is achieved for the automatic adjusting movement. 
         [0014]    It is furthermore proposed that at least one vane, including a first switchable valve device, is provided between the vanes which include the check valves in the circumferential direction. Due to the proposed approach, the available installation space in the rotor may be much better utilized for situating the pressure medium lines. This is advantageous, in particular, since two pressure medium lines empty into one of the working chambers which abut the vanes having the check valves, i.e., one pressure medium line emptying into the ring line and one pressure medium line leading to the third valve device, which run separately in at least one section. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The present invention is explained in greater detail below on the basis of one preferred exemplary embodiment. The following are shown in detail in the figures: 
           [0016]      FIG. 1 : shows a schematic representation of a camshaft adjusting device according to the present invention, including a circuit diagram of a pressure medium circuit in the position during an adjusting movement of the rotor from the “retard” direction into the central locking position; 
           [0017]      FIG. 2 : shows a schematic representation of a camshaft adjusting device according to the present invention, including a circuit diagram of a pressure medium circuit in the position during an adjusting movement of the rotor from the “advance” direction into the central locking position; 
           [0018]      FIG. 3 : shows a schematic representation of a camshaft adjusting device according to the present invention, including a circuit diagram of a pressure medium circuit during the adjusting movement in normal operation; and 
           [0019]      FIG. 4 : shows an alternative specific embodiment of the camshaft adjusting device according to the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    A camshaft adjusting device having a known basic structure with a schematically illustrated vane adjuster as a basic component is apparent from  FIGS. 1 through 3 , which includes a stator  16 , drivable by a crankshaft which is not illustrated, and a rotor  17 , which is rotatably fixedly connectable to a camshaft, also not illustrated, and which includes a rotor hub  36  and multiple vanes  11 ,  12  and  13  extending radially outwardly. In the upper representation, the vane adjuster is apparent in the developed view, while a detail of rotor hub  36  of rotor  17 , which includes a central locking device  33 , is schematically apparent at the bottom left, and a multi-way switching valve  21  for controlling the pressure medium flow is schematically apparent at the bottom right. 
         [0021]    A pressure medium circuit is also apparent, which includes a large number of pressure medium lines  1 ,  2 ,  3 ,  4 ,  5 ,  6 ,  7 ,  8 ,  23 ,  37 ,  38 ,  39  and  40 , which are optionally fluidically connectable to a pressure medium pump P or a pressure medium reservoir T, whereby, after the pressure medium has been fed back to pressure medium reservoir T via multi-way switching valve  21 , pressure medium pump P conveys it from there and back into the pressure medium circuit. 
         [0022]    Stator  16  includes a plurality of stator webs, which divide an annular space provided between stator  16  and rotor  17  into multiple pressure chambers  29 ,  30  and  31 . Pressure chambers  29 ,  30  and  31 , in turn, are divided by vanes  11 ,  12  and  13  of rotor  17  into working chambers  24 ,  25 ,  26 ,  27 ,  28  and  32 , into which pressure medium lines  1 ,  3 ,  4 ,  6 ,  7 ,  8 ,  39  and  40  empty. Central locking device  33  includes two locking pins  18  and  19 , which lock into a stator-fixed locking gate  22  for the purpose of locking rotor  17  with respect to stator  16 . Locking gate  22  may be situated, for example, in a sealing cover screwed to stator  16 . 
         [0023]    In principle, the rotation angle of the camshaft with respect to the crankshaft during normal operation, i.e., in the “advance” direction, is adjusted by the fact that pressure medium is applied to working chambers  24 ,  32  and  27 , thereby increasing their volume, while the pressure medium is simultaneously forced out of working chambers  25 ,  26  and  28 , which reduces their volume. Working chambers  24 ,  25 ,  26 ,  27 ,  28  and  32 , whose volume is increased in groups during this adjusting movement, are referred to, within the meaning of the present invention, as working chambers  24 ,  25 ,  26 ,  27 ,  28  and  32  of one operating direction, while working chambers  24 ,  25 ,  26 ,  27 ,  28  and  32 , whose volume is simultaneously decreased, are referred to as working chambers  24 ,  25 ,  26 ,  27 ,  28  and  32  of the opposite operating direction. The change in volume of working chambers  24 ,  25 ,  26 ,  27 ,  28  and  32  then results in the fact that rotor  17 , including vanes  11 ,  12  and  13 , is rotated with respect to stator  16 . In the top representation in  FIG. 3 , the volume of working chambers  25 ,  26  and  28  is increased by applying pressure medium via the B port of multi-way switching valve  21 , while the volume of working chambers  24 ,  32  and  27  is simultaneously decreased by the back-flow of the pressure medium via the A port of multi-way switching valve  21 . This change in volume then results in a rotation of rotor  17  with respect to stator  16 , which results in a shifting of vanes  11 ,  12  and  13  to the left in the direction of the arrow in the developed view. To enable rotor  17  to be adjusted with respect to stator  16 , central locking device  33  is first released by applying pressure medium to locking gate  22  via pressure medium lines  2  and  23  from the C port of multi-way switching valve  21  with the aid of pump P. By applying pressure medium to locking gate  22 , locking pins  18  and  19  are forced out of locking gate  22 , so that rotor  17  is able to subsequently rotate freely with respect to stator  16 . To this extent, the camshaft adjusting device corresponds to the prior art. 
         [0024]    According to the approach according to the present invention, pressure medium lines  34  and  35  are provided in vanes  11  and  12  and include check valves  9  and  10  situated therein, which facilitate an overflow of the pressure medium out of working chamber  25  into working chamber  24  and out of working chamber  32  into working chamber  26 . The flow of the pressure medium through pressure medium lines  34  and  35  may furthermore be blocked or facilitated by a second switchable valve device, formed by a spring-loaded, movable valve body  14  and  15 . For this purpose, valve bodies  14  and  15  have two switching positions, in which the flow-through is either released or blocked. Pressure medium may be applied to each of the switchable second valve devices via a pressure medium line  2  and  5 , and these second valve devices are transferred from a first to a second switching position, which is apparent in  FIG. 3 , upon the application of pressure medium with the aid of a shifting of valve bodies  14  and  15  against the active spring force. In the second switching position, the flow through pressure medium lines  34  and  35  is blocked, so that working chambers  24  and  25  or  32  and  26  are to be viewed as separate from each other, and the camshaft adjusting device may be operated with a correspondingly high degree of adjusting accuracy without an overflow of the pressure medium between working chambers  24 ,  25 ,  32  and  26 . 
         [0025]    Central locking device  33  furthermore includes a third valve device, formed by two locking pins  18  and  19  in rotor hub  36 . Locking pins  18  and  19  are designed as spring-loaded valve bodies, including corresponding grooves or bores, which are movable from a first switching position into a second switching position by applying pressure to locking gate  22  via pressure medium line  23  against the active spring force. Locking pins  18  and  19  are in the first switching position when they engage with locking gate  22  and the springs are relaxed. 
         [0026]    The bores or grooves in locking pins  18  and  19  are situated in such a way that a flow of the pressure medium in the first switching position of locking pin  18  is blocked between pressure medium line  1  and pressure medium line  39  and pressure medium lines  40  and  6  with an unloaded spring, as is apparent in the positions in  FIG. 1  and in  FIG. 2 . One of these positions illustrated in  FIG. 1  or  FIG. 2  is present if rotor  17  is not locked in the central locking position upon starting the internal combustion engine, and is rotated with respect to stator  16  either in the direction of the “retard” stop position or in the direction of the “advance” stop position. In the illustration, the “retard” stop position is identified by an S and the “advance” stop position by an F. 
         [0027]    In both positions of rotor  17 , one of locking pins  18  or  19  does not engage with locking gate  22  and is thus displaced into the second switching position against the spring force. The bores or grooves in locking pins  18  and  19  are situated in such a way that locking pins  18  and  19  facilitate a flow of the pressure medium between pressure medium lines  6  and  40  or  1  and  39  in the second switching position, while the flow through locking pin  18  or  19  engaging with locking gate  22  in the first switching position is blocked. 
         [0028]    Pressure medium lines  6  and  40  or  1  and  39  are fluidically connected to working chambers  25  and  26  or  24  and  32 , which are short-circuited thereby with the aid of locking pins  18  and  19  present in the second switching position. Pressure medium lines  3  and  8  empty into a partially annular or annular, shared pressure medium line  38  on rotor hub  36 , which, in turn, is fluidically connectable to pressure medium pump “P” or pressure medium reservoir “T” via the B port of multi-way switching valve  21 . With the aid of partial annular or annular pressure medium line  38 , pressure medium may be jointly applied to working chambers  25  and  28  of an operating direction, or these working chambers may be connected to pressure medium reservoir “T.” Pressure medium line  37  has the same function, via which pressure medium may be applied to working chambers  32  and  27  via the A port of multi-way switching valve  21 , or these working chambers are connectable to pressure medium reservoir “T.” Locking pins  18  and  19  separate each of pressure medium lines  1  and  39  or  6  and  40 , in the locking position, in which they engage with locking gate  22 , so that rotor  17  may be hydraulically supported, with active camshaft alternating torques, via working chamber  24  or working chamber  26  in the direction of the “advance” or “retard”: adjusting direction. 
         [0029]    Furthermore, a first switching valve device, formed by a spring-loaded, movable valve pin  20 , is provided in vanes  13  in which no check valve  9  or  10  is provided. Valve pin  20  has a pressure medium line  41 , e.g., in the form of a circumferential groove, through which working chambers  27  and  28  of different operating directions may be short-circuited on the side surfaces of vane  13  in a first switching position of the third valve device. 
         [0030]    In the event that the camshaft adjusting device is not locked in the central locking position upon starting the internal combustion engine, and instead is rotated with respect to stator  16  in the direction of the “retard” stop position, rotor  17  is automatically rotated out of this rotated position, as is apparent in  FIG. 1 , from the direction of the “retard” (S) stop position in the direction of the central locking position in the direction of the arrow, in that the alternating torques acting upon the camshaft (CTA—Camshaft Torque Actuated) are used to allow the pressure medium to flow out of working chamber  25  through pressure medium line  35  into working chamber  24  via check valve  9 . Since the other working chambers  27  and  28 , which are separated from each other by vanes  13 , each having one valve pin  20 , are short-circuited in this position of valve pin  20  via pressure medium line  41 , the pressure medium may overflow between these working chambers  27  and  28 . Since the pressure medium is furthermore unable to flow out of working chamber  24 , due to the locked position of locking pin  18 , and it is also unable to flow back into working chamber  25  via check valve  9 , rotor  17  is simultaneously unable to rotate back in the direction of the “retard” (S) stop position. Furthermore, working chamber  25 , out of which the pressure medium flows via check valve  9 , is fluidically connected via pressure medium line  40  and locking pin  19 , situated in the unlocked position, to working chamber  26  of the same operating direction, which is also separated from a working chamber  32  of the opposite operating direction by a vane  12  which includes a check valve  10 , so that the pressure medium is able to flow out of this working chamber  26  into working chamber  25  and finally into working chamber  24  via check valve  9  or out of working chamber  25  and into working chamber  28  via pressure medium lines  3 ,  38  and  8 , and from there into working chamber  27  via pressure medium line  41 . 
         [0031]    Due to the proposed circuit, rotor  17  is practically supported on the pressure medium present in working chamber  24 , the volume of working chamber  24  being increased by the pressure medium flowing in a pulsating manner via check valve  9 , and rotor  17  is rotated thereby with respect to stator  16 . Check valve  9  thus forms a freewheel, together with the correspondingly blocked or released pressure medium lines  1 ,  3 ,  4 ,  6 ,  7 ,  8 ,  39  and  40 , with the aid of which rotor  17  is rotated with respect to stator  16  on one side in the direction of the central locking position, utilizing the alternating torques acting upon the camshaft, until locking pin  19  engages with locking gate  22  or until locking pin  18  comes into contact laterally with a stop of locking gate  22 . Due to the engagement of locking pin  19  with locking gate  22 , the latter automatically enters the first switching position, due to the active spring force, in which the previously released flow connection between pressure medium lines  40  and  6  is blocked and the short circuit produced thereby is released. As a result, another rotational movement of rotor  17  with respect to stator  16  is prevented, and rotor  17  is locked in the central locking position. It is particularly important for the functionality of the freewheel that working chambers  25  and  26  of pressure chambers  29  and  30  having the decreasing volume during the automatic adjusting movement are fluidically connected via the groove or the bore in locking pin  19 , so that the pressure medium is able to flow out of working chamber  26  and does not impede the adjusting movement. 
         [0032]    The reverse adjusting procedure from the direction of the “advance” (F) stop position in the direction of the central locking position is apparent in  FIG. 2 . The principle of the adjusting movement is identical. In this case, locking pin  18  is in the second switching position and thereby establishes a flow connection between pressure medium lines  1  and  39 , so that working chambers  24  and  32  are fluidically connected to each other. Furthermore, locking pin  19  is in the first switching position and thereby blocks a flow of the pressure medium from working chamber  26  to working chamber  25 , so that working chamber  26  is decoupled from the pressure medium circuit. In this case, when alternating torques occur during the start phase of the internal combustion engine, the pressure medium flows out of working chamber  32  via pressure medium line  34  and check valve  10  present therein into working chamber  26  and thereby increases its volume, since the outflow of the pressure medium is simultaneously prevented by blocked pressure medium line  6 . At the same time, the pressure medium is unable to overflow from working chamber  24  into working chamber  25  due to the orientation of check valve  9 . In order that the pressure medium present in working chamber  24  does not impede the adjusting movement, working chamber  24  is fluidically connected to working chamber  32  of pressure chamber  30  of the same operating direction via locking pin  18 , which is in the second switching position, so that the pressure medium is able to flow out of working chamber  24  via pressure medium lines  1  and  39  into working chamber  32  and onward via check valve  10 . During this adjusting movement, rotor  17  is supported on stator  16  via the pressure medium present in working chamber  26 . 
         [0033]    During the adjusting movement illustrated in both  FIG. 1  and  FIG. 2 , multi-way switching valve  21  is in a basic position in which it is spring-loaded. During the shutdown of the internal combustion engine, multi-way switching valve  21  is automatically moved into the basic position, in which the C port is connected to pressure medium reservoir “T.” The C port is connected to locking gate  22  via pressure medium line  23  and to valve bodies  14  and  15  and to valve pin  20  via pressure medium lines  2 ,  5  and  42 , so that pressure medium is not applied to the first, second and third valve devices. If rotor  17  is not locked in the central locking position, the valve devices are either in the position shown in  FIG. 1  or in  FIG. 2 , and rotor  17  is automatically rotated in the direction of the central locking position upon startup according to the operating principle described above. For the purpose of the active, controlled rotation of rotor  17 , multi-way switching valve  21  is actuated and thereby displaced into a position in which pressure medium is applied to the C port and the B port via pressure medium pump “P,” and the A port is connected to pressure medium reservoir “T.” As a result, pressure medium is applied jointly to the valve devices, which are displaced into the second switching position against the active spring force, as is apparent in  FIG. 3 . As a result, valve bodies  14  and  15  and valve pin  20  are moved into a position in which the pressure medium is unable to overflow via vanes  11 ,  12  and  13 . At the same time, locking pins  18  and  19  are displaced into a position in which pressure medium lines  1  and  39  or  40  and  6  are fluidically connected to each other, so that working chambers  24  and  32  or  25  and  26  are also fluidically connected to each other. To adjust rotor  17  in the illustrated position in the direction of the “retard” (S) stop position, pressure medium is applied to working chambers  25  and  28  via shared pressure medium line  38  and pressure medium lines  8  and  3  branching therefrom, while the pressure medium flows out of working chambers  27  and  32  and back into pressure medium reservoir “T” via pressure medium lines  7  and  4  and via shared pressure medium line  37  with the aid of the A port. Since working chambers  24  and  26  are simultaneously fluidically connected to working chambers  32  and  25  via locking pins  18  and  19 , the pressure medium is also introduced into working chamber  26  and is removed from working chamber  24 . 
         [0034]    It is furthermore particularly important for the present invention that working chambers  24 ,  25 ,  26 ,  27 ,  28  and  32  of different operating directions, which are not part of the presently active freewheel, are each short-circuited via a valve pin  20 , so that the automatic adjusting movement is not impeded by the pressure medium present in working chambers  24 ,  25 ,  26 ,  27 ,  28  and  32 . It is particularly advantageous that valve pins  20  are situated in vanes  13  themselves, since this makes it possible to facilitate the overflow of the pressure medium directly without additional pressure medium lines. 
         [0035]    A further developed specific embodiment of the camshaft adjusting device according to the present invention is apparent in  FIG. 4 , in which pressure chambers  29  and  30 , including vanes  11  and  12  with check valves  9  and  10 , are not situated adjacent to each other, but instead encompass between them another pressure chamber  31 , including a vane  13  with a pressure medium line  41  short-circuiting working chambers  27  and  28 . Due to this refinement, the pressure medium lines, which are provided in rotor  17  by bores and grooves, may be situated in a much simpler manner. This is particularly advantageous because the available installation space for accommodating the pressure medium lines in rotor  17  is limited, and the pressure medium lines generally should not be allowed to cross, except for certain nodes. If rotor  17  includes four vanes  11 ,  12  and  13 , for example, vanes  11  and  12 , including check valves  9  and  10 , or vane  13 , including the first valve devices, are situated opposite to each other. The course of the pressure medium lines may be simplified thereby, it being possible, in particular, to make much better use of the material of rotor  17  for accommodating the pressure medium lines. 
       LIST OF REFERENCE NUMERALS 
       [0000]    
       
           1  pressure medium line 
           2  pressure medium line 
           3  pressure medium line 
           4  pressure medium line 
           5  pressure medium line 
           6  pressure medium line 
           7  pressure medium line 
           8  pressure medium line 
           9  check valve 
           10  check valve 
           11  vane 
           12  vane 
           13  vane 
           14  valve body 
           15  valve body 
           16  stator 
           17  rotor 
           18  locking pin 
           19  locking pin 
           20  valve pin 
           21  multi-way switching valve 
           22  locking gate 
           23  pressure medium line 
           24  working chamber 
           25  working chamber 
           26  working chamber 
           27  working chamber 
           28  working chamber 
           29  pressure chamber 
           30  pressure chamber 
           31  pressure chamber 
           32  working chamber 
           33  central locking device 
           34  pressure medium line 
           35  pressure medium line 
           36  rotor hub 
           37  pressure medium line 
           38  pressure medium line 
           39  pressure medium line 
           40  pressure medium line 
           41  pressure medium line 
           42  pressure medium line