Patent Publication Number: US-9404396-B2

Title: Motor vehicle valve train adjustment device

Description:
This is a continuation-in-part application of international patent application PCT/EP2013/000231 filed Jan. 25, 2013 and claiming the priority of German patent application 10 2012 004 419.4 filed Mar. 18, 2012. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention relates to a motor vehicle valve train adjustment device comprising a camshaft with at least two cam elements which are axially displaceably supported and of which at least one has a cam track with a predetermined cam lift and a cam track with zero lift for cylinder deactivation. 
     A motor vehicle valve train adjustment device is already known that has at least one camshaft that comprises at least two axially displaceably arranged cam elements, wherein at least one cam element of the at least two cam elements has a cam track with valve lift and a cam track with zero lift for cylinder deactivation. 
     It is the principal object of the present invention to provide a motor vehicle valve train adjustment device with a particularly advantageous cylinder deactivation system. 
     SUMMARY OF THE INVENTION 
     In a motor vehicle valve train adjustment device comprising at least one camshaft with at least two axially displaceable cam elements wherein at least one cam element has a cam track with a valve lift and a cam track with zero valve lift for a deactivation of at least one cylinder, and at least one other cam element of the at least two axially displaceable cam elements has a cam track with a first valve lift and a cam track with a second valve lift by which a cylinder which remains fueled during a partial cylinder deactivation is adapted to the at least one cylinder deactivation by special valve lift characteristics. 
     A “camshaft” is in particular to be understood to be a shaft that is provided for actuating a plurality of valves of an internal combustion engine and that has in each case at least one cam track for actuating a valve. In this respect it is conceivable that a camshaft is provided with intake cam elements for actuating intake valves and also exhaust cam elements for actuating exhaust valves. 
     A “cam element” is in particular to be understood as being an element that is arranged in a rotationally fixed manner on a camshaft, and for actuating a valve; it is provided for directly or indirectly acting on the corresponding valve with at least one lift. “Rotationally fixed” is in particular to be understood as a connection that transmits a torque and/or a rotational movement without changes. “Axial” is in particular to be understood as axial with regard to a main rotational axis of the cam shaft. “Axially displaceable” is in particular to be understood such that the cam element can be displaced on the camshaft parallel to the main rotational axis of the cam shaft between at least two switching positions. A “cam track” is in particular to be understood as a region of the cam element, which extends on the circumference of the cam element and which forms a valve actuation curve for valve actuation and/or defines the valve actuation. A “zero lift” is in particular to be understood such that a valve that is actuated with the zero lift has a valve lift that is constant during a full revolution of the cam element and preferably remains in its valve seat, so that a flow cross-section of the respective gas passage remains blocked throughout the entire time the zero lift is engaged. Here, the cam track with zero lift preferably remains without contact to the corresponding valve that is it does not touch it. While a cam element with zero lift is engaged, the corresponding valve remains non-actuated. A “valve lift” is in particular to be understood as a valve movement initiated by the cam tracks of the cam elements during which the valve preferably lifts off from its valve seat and thus opens a flow cross-section. “Cylinder deactivation” is in particular to be understood such that at least one cylinder of the internal combustion engine is deactivated during operation while at least one other cylinder of the internal combustion engine is still fueled. A “first valve lift and a second valve lift” is in particular to be understood as two valve lifts that differ from one another. Here, the valve lifts can differ in terms of theft lift height and/or their lift characteristics and/or can open and close the valves at different times. 
     Furthermore, it is proposed that the valve train adjustment device of the engine of the motor vehicle has a control and/or feedback control unit for the purpose of operating, in a deactivating operating state, the at least one cam element with zero lift and the at least one other cam element with a valve lift that is associated with relatively low engine power output needs. In this way, the motor vehicle valve train adjustment can be operated in particular during cylinder deactivation in a particularly advantageous manner. A “control and/or feedback control unit” is in particular to be understood as being a unit that has at least one control device. A “control device” is in particular to be understood as being a unit comprising a processor unit and a storage unit as well as an operating program that is stored in the storage unit. The control and/or feedback control unit principally can comprise a plurality of interconnected control devices which are preferably provided for communicating with each other via a bus system such as, in particular, a CAN bus system. “Provided” is in particular to be understood as specifically programmed, designed and/or equipped. “Deactivating operating state” is in particular to be understood as an operating state in which at least one cylinder is deactivated. “Operating a cam element with zero lift” is in particular to be understood to mean that the cam element with the cam element of the cam track that has the zero lift is engaged with the corresponding valve. 
     In addition, it is proposed that the motor vehicle valve train adjustment device has at least one exhaust camshaft that comprises at least two cam elements arranged in an axially displaceable manner, wherein at least one cam element of the at least two cam elements has a cam track with valve lift and a cam track with zero lift for cylinder deactivation. As a result, cylinder deactivation can be carried out in a particularly advantageous manner. 
     Moreover, it is proposed that the at least one other cam element of the at least two cam elements of the exhaust camshaft has a cam track with a first valve lift and a cam track with a second valve lift. In this way, the at least one other cam element that is associated with a cylinder that is still operative during cylinder deactivation in the partial cylinder deactivating engine operating state in a particularly advantageous manner. 
     Furthermore, it is proposed that the motor vehicle valve train adjustment device has a control and/or feedback control unit that is provided so as to switch, in at least one operating state, all cams of the intake camshaft, and to switch only cam elements to be deactivated of the exhaust camshaft. In this way, the cam elements for cylinder deactivation can be switched in a particularly simple manner. 
     A “cam element to be deactivated” is in particular to be understood as a cam element that has a cam track with zero lift for cylinder deactivation, and in particular for cylinder deactivation, it is switched into a switching position in which the cam track having the zero lift is engaged with the corresponding valve. 
     It is further proposed that the control and/or feedback control unit that is adapted to switch, in at least one operating state, all cam elements of the camshaft designed as an intake camshaft and of the camshaft designed as an exhaust camshaft. In this way, in particular the cam elements of the exhaust camshaft can be switched in a particularly advantageous manner for cylinder deactivation. 
     Furthermore, it is proposed that the control unit is adapted to switch, in at least one operating state, at least one cam element of the exhaust camshaft to a zero lift, and at least one cam element of the exhaust camshaft to one of the valve lifts that is associated with lower power. In this way, the internal combustion engine can be operated during cylinder deactivation in a particularly advantageous and efficient manner. 
     The invention will become more readily apparent from the following description thereof with reference to the accompanying drawing. In the drawing, an exemplary embodiment of the invention is illustrated. The drawing, the description and the claims include a multiplicity of features in combination. The person skilled in the art will also advantageously view the features individually and combine them into further suitable combinations. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows an exemplary embodiment of a motor vehicle valve train adjustment device. The vehicle valve train adjustment device is part of an internal combustion engine for a motor vehicle, which is not illustrated in greater detail. The internal combustion engine is a four cylinder engine of a motor vehicle that is not illustrated. It is principally also conceivable that the internal combustion engine has a different number of cylinders as it may appear to be practical to the person skilled in the art. For each cylinder, the internal combustion engine has two exhaust valves which are not shown. It is principally also conceivable that the internal combustion engine has for each cylinder only one intake valve and one exhaust valve, or a different number of intake and/or exhaust valves as it appears to be practicable to the person skilled in the art. The motor vehicle valve train adjustment device has a camshaft  10  in the form of an intake camshaft that is provided for actuating the intake valves and an exhaust camshaft  11  actuating the exhaust valves. The camshafts  10 ,  11  are rotatably mounted in a cylinder head of the internal combustion engine. 
     The intake camshaft  10  comprises four cam elements  12 ,  13 ,  14 ,  15  which are arranged axially displaceable. The cam elements  12 ,  13 ,  14 ,  15  are connected to the intake camshaft  10  in a rotationally fixed manner via a positive-locking fit, which is not illustrated in greater detail. In an axial direction that runs parallel to a rotational axis of the camshaft  10 , the cam elements  12 ,  13 ,  14 ,  15  can be moved between two switching positions. It is principally also conceivable that the cam elements  12 ,  13 ,  14 ,  15  are connected to the camshaft  10  in a different manner that appears to be practicable to the person skilled in the art. The first cam element  12  is associated with the first cylinder and with the corresponding intake valves. The second cam element  13  is associated with the second cylinder and the corresponding intake valves. The third tarn element  14  is associated with the third cylinder and with the corresponding intake valves. The fourth cam element  15  is associated with the fourth cylinder and with the corresponding intake valves. 
     The axially displaceable cam elements  12 ,  13 ,  14 ,  15  are provided for actuating and adjusting a valve lift of in each case two intake valves of a cylinder. For this purpose, the cam elements  12 ,  13 ,  14 ,  15  have in each case two cam tracks  20 ,  21 ,  22 ,  23 ,  28 ,  29 ,  30 ,  31 ,  36 ,  37 ,  38 ,  39 ,  44 ,  45 ,  46 ,  47  for in each case one valve intake valve. Each of the cam elements  12 ,  13 ,  14 ,  15  has two first cam tracks  20 ,  21 ,  22 ,  23 ,  36 ,  37 ,  38 ,  39  and two second cam tracks  28 ,  29 ,  30 ,  31 ,  44 ,  45 ,  46 ,  47 . In each case, one first cam track  20 ,  21 ,  22 ,  23 ,  36 ,  37 ,  38 ,  39  and a second cam track  28 ,  29 ,  30 ,  31 ,  44 ,  45 ,  46 ,  47  are associated with the same inlet valve of a cylinder and have different valve lifts and/or lift characteristics, The first cam tracks  20 ,  21 ,  22 ,  23 ,  36 ,  37 ,  38 ,  39  and the second cam tracks  28 ,  29 ,  30 ,  31 ,  44 ,  45 ,  46 ,  47  which are each associated with the same intake valve of the respective cylinder are in each case arranged adjacently on the respective cam element  12 ,  13 ,  14 ,  15 , The first cam tracks  20 ,  21   22 ,  23 ,  36 ,  37 ,  38 ,  39  of all cam elements  12 ,  13 ,  14 ,  15  of the intake camshaft  10  have a first valve lift. Here, the first valve lifts that are initiated by the first cam tracks  20 ,  21 ,  22 ,  23 ,  36 ,  37 ,  38 ,  39  of the cam elements  12 ,  13 ,  14 ,  15  are identical. The first valve lifts that are initiated by the first cam tracks  20 ,  21 ,  22 ,  23 ,  36 ,  37 ,  38 ,  39  of the cam elements  12 ,  13 ,  14 ,  15  differ from one another only in terms of a chronological sequence. The second cam tracks  44 ,  45 ,  46 ,  47  of the first cam element  12  and the fourth cam element  15  have a second valve lift. Here, the second valve lifts that are initiated by the second cam tracks  44 ,  45 ,  46 ,  47  of the first cam element  12  and the fourth cam element  15  are formed identically. The second valve lifts that are initiated by the second cam tracks  44 ,  45 ,  46 ,  47  of the first cam elements  12  and the fourth cam element  15  differ from one another only in terms of a chronological sequence. The second cam tracks  28 ,  29 ,  30 ,  31  of the second cam element  13  and the third cam element  14  have a zero lift for cylinder deactivation. During a full revolution of the cam elements  13 ,  14 , no actuation is caused by the second cam tracks  28 ,  29 ,  30 ,  31  of the second and third cam elements  13 ,  14 . The second cam tracks  28 ,  29 ,  30 ,  31  of the second and third cam elements  13 ,  14  have a maximum distance from the main rotational axis of the camshaft  10  that is less than that of the first cam tracks  20 ,  21 ,  22 ,  23 ,  36 ,  37 ,  38 ,  39  The second cam tracks  28 ,  29 ,  30 ,  31  of the second and third cam elements  13 ,  14  are without contact to the associated intake valve during a full revolution of the corresponding cam element  13 ,  14 . The second cam tracks  28 ,  29 ,  30 ,  31  of the second and third cam element  13 ,  14  do not actuate the intake valves so that the respective cylinder is not filled with a fuel/air mixture and thus cannot be ignited. While the second cam tracks  28 ,  29 ,  30 ,  31  of the second and third cam element  13 ,  14  are engaged, the corresponding cylinder is deactivated and does not generate a drive torque. It is principally also conceivable that the second cam tracks  28 ,  29 ,  30 ,  31  of the second and third cam elements  13 ,  14  touch the corresponding intake valve, but do not lift it out of its valve seat. 
     In a first switching position of the cam elements  12 ,  13 ,  14 ,  15 , the first cam tracks  20 ,  21 ,  22 ,  23 ,  36 ,  37 ,  38 ,  39  actuate the corresponding intake valves. In a second switching position of the cam elements, the second cam tracks  44 ,  45 ,  46 ,  47  of the first cam element  12  and the fourth cam element  15  actuate the corresponding inlet valve with the second valve lift, while the second cam element  13  and the third cam element  14  have the cam tracks  28 ,  29 ,  30 ,  31  with zero lift in engagement, and the corresponding intake valves therefore remain non-actuated. In order to adjust a valve lift of the intake valves of a cylinder, the corresponding cam element  12 ,  13 ,  14 ,  15  are switched from one switching position into the other switching position. 
     In each case two adjacent cam elements  12 ,  13 ,  14 ,  15  of an intake camshaft  10 , are designed to be switched together as a cam element group  53 ,  54 . The first cam elements  12  that is associated with the first cylinder, and the second cam element  13  that is associated with the second cylinder, form the first cam element group  53  to be switched together. The third cam element  14  that is associated with the third cylinder and the fourth cam element  15  that is associated with the fourth cylinder, form the second cam element group  54  that is to be switched together. The cam elements  12 ,  13 ,  14 ,  15  of one of the cam element groups  53 ,  54  are each formed separately from one another as separate individual components. The cam elements  12 ,  13 ,  14 ,  15  of a cam element group  53 ,  54  are in each case switched together during a switching process. The two cam element groups  53 ,  54  can be switched independently of one another. The first cam element group  53  that is formed by the first cam element  12  and the second cam element  13 , and the second cam element group  54  that is formed by the third cam element  14  and the fourth carry element  15 , can be switched independently from one another. 
     The motor vehicle valve train adjustment device comprises two actuator devices  55 ,  56  which are associated with the camshaft intake camshaft  10 . In each case one actuator device  55 ,  56  is associated with one of the cam element groups  53 ,  54  of the intake camshaft  10 . The actuator devices  55 ,  56  interconnect the cam elements  12 ,  13 ,  14 ,  15  of their associated cam element group  53 ,  54  during a switching process. The first actuator device  55  is associated with the first cam element group  53  and is provided for switching the first cam element  12  and the second cam element  13 . The second actuator device  56  is associated with the second cam element group  54  and is provided for switching the third cam element  14  and the fourth cam element  15 . 
     The first actuator device  55  and the second actuator device  56  are structurally identical. The actuator devices  55 ,  56  each have a schematically illustrated guide path  57 . The actuator devices  55 ,  56  comprise an actuator each with a switching element in the form of a switching pin. During a switching process, the switching elements engage into the corresponding guide path  57  of the actuator device  55 ,  56 , The actuator devices  55 ,  56  each switch in a first instance a cam element  12 ,  14  from one switching position into the other switching position and subsequently switch the other cam element  13 ,  15  of the corresponding cam element group  53 ,  54  from one switching position into the other switching position. 
     The camshaft  11  which is an exhaust camshaft likewise comprises four cam elements  16 ,  17 ,  18 ,  19  that are arranged to be axially displaceable. The cam elements  16 ,  17   18 ,  19  are connected to the exhaust camshaft  11  in a rotationally fixed manner via a positive-locking fit, which is not illustrated in greater detail. In the axial direction of the camshaft  11 , the cam elements  16 ,  17 ,  18 ,  19  can be moved between two switching positions. It is principally also conceivable that the cam elements  16 ,  17 ,  18 ,  19  are connected to the camshaft  11  in a different manner that appears to be practicable to the person skilled in the art. The first cam element  16  is associated with the first cylinder and with the corresponding exhaust valves. The second cam element  17  is associated with the second cylinder and with the corresponding exhaust valves. The third cam element  18  is associated with the third cylinder and with the corresponding exhaust valves. The fourth cam element  19  is associated with the fourth cylinder and with the corresponding exhaust valves. 
     The axially displaceable cam elements  16 ,  17 ,  18 ,  19  are provided for actuating and adjusting a valve lift of in each case two exhaust valves of a cylinder. For this purpose, the cam elements  16 ,  17 ,  18 ,  19  have in each case two cam tracks  24 ,  25 ,  26 ,  27 ,  32 ,  33 ,  34 ,  35 ,  40 ,  41 ,  42 ,  43 ,  48 ,  49 ,  50 ,  51  for in each case one exhaust valve. Each of the cam elements  16 ,  17 ,  18 ,  19  has two first cam tracks  24 ,  25 ,  26 ,  27 ,  40 ,  41 ,  42 ,  43  and two second cam tracks  32 ,  33 ,  34 ,  35 ,  48 ,  49 ,  50 ,  51 . In each case one first cam track  24 ,  25 ,  26 ,  27 ,  40 ,  41 ,  42 ,  43  and a second cam track  32 ,  33 ,  34 ,  35 ,  48 ,  49 ,  50 ,  51  which are associated with the same exhaust valve of a cylinder have different valve lifts and/or lift characteristics. The first cam tracks  24 ,  25 ,  26 ,  27 ,  40 ,  41 ,  42 ,  43  and the second cam tracks  32 ,  33 ,  34 ,  35 ,  48 ,  49 ,  50 ,  51  which are each associated with the same valve of the respective cylinder are in each case arranged adjacently on the respective cam element  16 ,  17 ,  18 ,  19 . The first cam tracks of all cam elements  24 ,  25   26 ,  27 ,  40 ,  41 ,  42 ,  43  have a first valve lift. Here, the first valve lifts that are initiated by the first cam tracks  24 ,  25 ,  26 ,  27 ,  40 ,  41 ,  42 ,  43  of the cam elements  16 ,  17 ,  18 ,  19  are formed identically. The first valve lifts that are initiated by the first cam tracks  24 ,  25 ,  26 ,  27 ,  40 ,  41 ,  42 ,  43  of the cam elements  16 ,  17 ,  18 ,  19  differ from one another only in terms of a chronological sequence of activation. The second cam tracks  48 ,  49 ,  50 ,  51  of the first cam element  16  and the fourth cam element  19  have a second valve lift. Here, the second valve lifts that are initiated by the second cam tracks  48 ,  49 ,  50 ,  51  of the first cam element  16  and the fourth cam element  19  are formed identically. The second valve lifts that are initiated by the second cam tracks  48 ,  49 ,  50 ,  51  of the first cam element  16  and the fourth cam element  19  differ from one another only in terms of a chronological sequence of activation. The second cam tracks  32 ,  33 ,  34 ,  35  of the second cam element  17  and the third cam element  18  have a zero lift for cylinder deactivation. During a full revolution of the cam elements  17 ,  18 , no valve actuation is caused by the second cam tracks  32 ,  33 ,  34 ,  35  of the second cam element  17  and the third cam elements  18 . The second cam tracks  32 ,  33 ,  34 ,  35  of the second and third cam elements  17 ,  18  have a maximum distance from the main rotational axis of the camshaft  11  that is less than that of the first cam tracks  24 ,  25 ,  26 ,  27 ,  40 ,  41 ,  42 ,  43 . The second cam tracks  32 ,  33 ,  34 ,  35  of the second and third cam elements  17 ,  18  are without contact to the associated exhaust valve, during a full revolution of the corresponding cam element  17 ,  18 . The second cam tracks  32 ,  33 ,  34 ,  35  of the second and third cam elements  17 ,  18  do not actuate the valves designed as exhaust valves so that no gas can escape from the corresponding cylinder through the exhaust valves. While the second cam tracks  32 ,  33 ,  34 ,  35  of the second and third cam elements  17 ,  18  are engaged, the corresponding cylinder are deactivated and do not generate a drive torque. It is principally also conceivable that the second cam tracks  32 ,  33 ,  34 ,  35  of the second and third cam elements  17 ,  18  touch the corresponding exhaust valve, but do not lift it out of its valve seat. 
     In a first switching position of the cam elements  16 ,  17 ,  18 ,  19 , the first cam tracks  24 ,  25 ,  26 ,  27 ,  40 ,  41 ,  42 ,  43  of the corresponding cam elements  16 ,  17   18 ,  19  actuate the corresponding exhaust valves. In a second switching position of the cam elements  16 ,  17 ,  18 ,  19 , the second cam tracks  48 ,  49 ,  50 ,  51  of the first cam element  16  and the fourth cam element  19  actuate the corresponding exhaust valve with the second valve lift, while the second cam element  17  and the third cam element  18  have the cam tracks  32 ,  33 ,  34 ,  35  with zero lift in engagement, and the corresponding exhaust valves therefore remain non-actuated. In order to adjust a valve lift of the exhaust valves of a cylinder, the corresponding cam element  16 ,  17 ,  18 ,  19  is switched from one switching position into the other switching position. 
     In each case two of the cam elements  16 ,  17 ,  18 ,  19  of the exhaust camshaft  11 , which cam elements are arranged adjacently, are switched together as a cam element group  58 ,  59 . The first cam element  16  that is associated with the first cylinder and the second cam element  17  that is associated with the second cylinder form the first cam element group  58  to be switched together. The third cam element  18  that is associated with the third cylinder and the fourth cam element  19  that is associated with the fourth cylinder form the second cam element group  59  that is to be switched together. The cam elements  16 ,  17 ,  18 ,  19  of one of the cam element groups  58 ,  59  of the exhaust camshaft  11  are each formed separately from one another as separate individual components. The cam elements  16 ,  17 ,  18 ,  19  of a cam element group  58 ,  59  of the exhaust camshaft  11  are in each case switched together during a switching process. The two cam element groups  58 ,  59  of the exhaust camshaft  11  can be switched independently of one another. The first cam element group  58  that is formed by the first cam element  16  and the second cam element  17 , and the second cam element group  59  that is formed by the third cam element  18  and the fourth cam element  19 , can be switched independently from one another. 
     The motor vehicle valve train adjustment device comprises two actuator devices  60 ,  61  which are associated with the exhaust camshaft  11 . In each case one actuator device  60 ,  61  is associated with one of the cam element groups  58 ,  59  of the exhaust camshaft  11 . The actuator devices  60 ,  61  interconnect the cam elements  16 ,  17 ,  18 ,  19  of their associated cam element group  58 ,  59  during a switching process. The first actuator device  60  is associated with the first cam element group  58  for switching the first cam element  16  and the second cam element  17 . The second actuator device  61  is associated with the second cam element group  59  for switching the third cam element  18  and the fourth cam element  19 . 
     The first actuator device  60  and the second actuator device  61  of the exhaust camshaft  11  are structurally identical to the actuator devices  55 ,  56  of the intake camshaft  10 . The actuator devices  60 ,  61  each have a schematically illustrated guide path  62 . The actuator devices  60 ,  61  comprise an actuator with in each case a switching element in the form of a switching pin. During a switching process, the switching elements engage into the corresponding guide path  62  of the actuator device  60 ,  61 . The actuator devices  60 ,  61  switch in a first instance a cam element  16 ,  18  from one switching position into the other switching position and subsequently switch the other cam element  17 ,  19  of the corresponding cam element group  58 ,  59  from one switching position into the other switching position. 
     The motor vehicle valve train adjustment device comprises a control and feedback control unit  52 . for switching the actuator devices  55 ,  56  associated with the intake camshaft  70 , and also for switching the actuator devices  60 ,  61  associated with the exhaust camshaft  11 . By activation of the control and feedback control unit  52 , the cam elements  12 ,  13 ,  14 ,  15  of the intake camshaft  10  and the cam elements  16 ,  17 ,  18 ,  19  of the exhaust camshaft  11  can be switched. 
     The control and feedback control unit  52  has a deactivating operating state for cylinder deactivation. In the deactivating operating state, the control and feedback control unit  52  is provided for operating the cam elements  13 ,  14  of the intake camshaft  10 , which cam elements have a cam track  28 ,  29 ,  30   31  with zero lift and for operating the other cam elements  12 ,  15  of the intake camshaft  11  with the second valve lift. Here, the second valve lift, with which the cam elements  12 ,  15  are operated, is associated with lower power. Power that can be provided by the corresponding cylinder when the corresponding cam element  12  is operated with the second valve lift is lower than the power that can be provided by the cylinder when the corresponding cam element  12 ,  15  is operated with the first valve lift. For this purpose, starting from a normal operating state in which all cam elements  12 ,  13 ,  14 ,  15  of the intake camshaft  10  are engaged by the first cam track  20 ,  21 ,  22 ,  23 ,  36 ,  37 ,  38 ,  39  and thus are operated with the first valve lift, the control and feedback control unit  52 , for switching the deactivating operating state by means of the actuator devices  55 ,  56 , switches all cam elements  12 ,  13 ,  14 ,  15  of the intake camshaft  10  from the first switching position into the second switching position in which the cam elements  12 ,  13 ,  14 ,  15  each are displaced and the second cam tracks  28 ,  29 ,  30 ,  31 ,  44 ,  45 ,  46 ,  47  are activated. 
     For switching into the deactivating operating state, the control and feedback control unit  52  also switches all cam elements  16 ,  17 ,  18 ,  19 . The control and feedback control unit is provided here for switching the second and the third cam elements  17 ,  18  of the exhaust camshaft  11  to a zero lift, and for switching the first and the fourth cam elements  16 ,  19  of the exhaust camshaft  11  to the second valve lift that is associated with lower power. In doing so, the control and feedback control unit  52  switches all cam elements  16 ,  17 ,  18 ,  19  into the second switching position by means of the actuator devices  60 ,  61 . In this way, the second cam element  17  and the third cam element  18  actuate the corresponding exhaust valves for zero lift, whereby the corresponding valves remain non-actuated. The first cam element  16  and the fourth cam element  19  actuate the corresponding exhaust valves so as to provide the second valve lift. 
     It is principally also conceivable that only the cam elements  17 ,  18  of the exhaust camshaft  11 , which comprise the cam tracks  32 ,  33 ,  34 ,  35  with zero lift are designed to be switchable and are switched for cylinder deactivation. In this case it would be conceivable that the first cam element  16  and the fourth cam element  19  only comprise the first cam track  40 ,  41 ,  42 ,  43 . In this case, as illustrated in  FIG. 1  by dashed lines, only one actuator device would be needed which switches the second cam element  17  and the third cam element  18 , which in this case would be combined into a cam element group, between the first switching position and the second switching position. For switching into the deactivating operating state, the control and feedback control unit  52  is provided in this case for switching only the cam elements  17 ,  18  of the exhaust camshaft  11 , which cam elements have each a cam track with zero lift. For switching the deactivating operating state, the control and feedback control unit  52  switches in this case only the second cam element  17  and the third cam element  18  of the exhaust camshaft  11  from the first switching position into the second switching position. The first cam element  16  and the fourth cam element  19  of the exhaust camshaft  11  are not switched herein. Switching the cam elements  12 ,  13 ,  14 ,  15 , of the intake camshaft  10  remains as described above. For switching the deactivating operating state, however, the control and feedback control unit  52  switches all cam elements  12 ,  13 ,  14 ,  15  of the intake camshaft  10  from the first switching position into the second switching position.