EP3170997B1 - Variable valve drive with a rocker arm - Google Patents

Description

The invention relates to a variable valve train for a lift valve, in particular for a charge exchange valve of an internal combustion engine, which is periodically movable between a closed and an open position by a cam via a rocker arm.

It is known to operate gas exchange valves of an internal combustion engine variable with different opening and closing times and with different valve opening strokes. Such variable valve trains offer the advantageous possibility of targeted adjustment of the course of the valve lift over the cam angle as a function of operating parameters of the device equipped with the respective lift valve, that is, for example, depending on the speed, load or temperature of an internal combustion engine.

In particular, it is known to generate a plurality of different lift curves for a lift valve in that a plurality of cams are present for the actuation of this lift valve, and that in each case the contour of only one cam effects the lift progression. To switch to another stroke course is switched to the contour of another cam. Such a valve control is from the DE 42 30 877 A1 previously known. In this case, a camshaft block with two different cam contours is rotatably but axially displaceably arranged on a camshaft. According to the axial position of the cam block is a cam contour via an intermediate member (transmission lever) with the lifting valve in operative connection. The axial displacement of the cam block to change the valve parameters takes place during the Grundkreisphase against the action of a return spring by means of a pressure ring.

From the DE 195 19 048 A1 is a variable valve train for an internal combustion engine previously known, in which also two differently shaped in their cam contour cams are arranged directly adjacent to each other on the camshaft. The change of the cam engagement is effected by an axial displacement of the camshaft with the cam located on it.

Furthermore, from the DE 195 20 117 C2 a valve train of an internal combustion engine previously known, in which on the camshaft rotationally fixed an axially displaceable cam block is arranged with at least two different cam tracks. The adjustment of the cam block via an adjusting member, which is guided inside the camshaft. By a frontal side arranged on the camshaft double-acting hydraulic or pneumatic piston-cylinder unit, the adjusting member is moved inside the camshaft. The adjusting member is connected to a driving piece, which penetrates an axially arranged in the camshaft slot and opens into a bore of the cam block.

A disadvantage of the cited prior art is the high space requirement, which is required for adjusting the cam block or for the axial adjustment of the camshaft.

Furthermore, from the DE 41 42 197 A1 a rocker arm assembly for a variable valve train is known, wherein a first rocker arm of each rocker arm is associated with a cam with a small cam lift and a second rocker cam with a large cam lift, each with a locking device for each pair of rocker, through which only the larger cam lift when switched on having cam for both rocker arm is effective. A disadvantage of this known valve train is the need for an external spring stop to ensure the return of the second rocker arm. This and the independent storage of the second rocker arm also allow no pre-assembly. Likewise, the two levers need a driving point, which leads to the fact that the two cam profiles must be symmetrical to each other or the apex of the two cams have no angular offset from each other. This prevents the possibility of varying the phase position of the valve lifts.

Similar designs with selectively coupled to each other Kipphebeln, each cooperating with differently shaped cam, are also from the JP 2006 132378 A , of the DE 44 12 851 A1 , of the WO 2004/033862 A1 and DE 36 13 945 A1 known. In all cases, however, are independently pivotable about a common axis mounted Kipphebelanordnungen, which thus also do not allow pre-assembly of the assembly.

The patent US 5 080 054 A also discloses that even for a cam follower valve drive, a variable valve control can be realized on the principle of a lockable lever arrangement which is in operative contact with differently shaped cams.

Further, the US Pat. No. 7,311,073 B1 a variable valve train for a finger follower arrangement, wherein the adjustment of the valve lift takes place via a plurality of cams with different cam contours via a transmission element additionally mounted between the camshaft and the valve lever. This one is on an additional one Shaft pivotally mounted transfer rocker arm, which is in operative contact with a second eccentrically mounted to the additional shaft transfer rocker arm over a contour surface. By rotating the additional shaft changes due to the eccentricity of the contact area on the contour surface and thus the transmitted to the valve stroke. A disadvantage of this arrangement, however, are the number of additional components for the transmission mechanism and the additional space requirement.

It is an object of the invention to provide an improved variable valve train with a rocker arm, with which disadvantages of conventional techniques can be avoided. The invention is based in particular on the object of a structurally compact and easy-to-install design of such a variable valve train.

These objects are achieved by a variable valve train with the features of the independent claim. Advantageous embodiments and applications of the invention are the subject matter of the dependent claims and are explained in more detail in the following description with partial reference to the figures.

According to the invention, a variable valve drive is provided for a lift valve. The lift valve is between a closed and an open position, in particular against the force of a return spring, indirectly movable by a cam of a camshaft via a rocker arm periodically. The lift valve is preferably a charge exchange valve of an internal combustion engine.

According to general aspects of the invention, the valve train comprises a camshaft, comprising at least one first cam and at least one offset in the longitudinal direction of the camshaft second cam, wherein the at least one first cam and the at least one second cam are designed differently in their cam contour. For example, the cam contour of the at least one first cam to the cam contour of the at least one second cam may have a different cam lobe and / or a different phase position. Preferably, the at least one second cam has a larger cam lift (cam lift) than the at least one first cam.

The cam contours each determine, taking into account the valve clearance according to their training, the opening and closing time and / or the opening stroke of the lift valve. A second cam may be disposed immediately adjacent to a first cam.

The valve drive further comprises a rocker arm mounted pivotably about a rocker arm axis, which is assigned at its camshaft-side end via a roller, in particular a pressure roller, of the first cam and is in operative connection with the lift valve at its valve-side end. One arm of the rocker arm thus serves to actuate the lift valve, the other lever arm is driven by a cam. The rocker arm is preferably mounted on a central region on the rocker shaft.

The valve drive further comprises a roller lever which is assigned at its camshaft-side end to the at least one second cam via at least one roller, d. H. the movement of the / the second cam (s) picks up, and is articulated at its other end on the rocker arm about the rocker arm pivotally.

Further, the valvetrain comprises a switchable hydraulic locking means by which the rocker arm and the roller lever can be selectively locked together, wherein rocker arms and roller levers follow the movement of the at least one second cam or can be unlocked from each other, wherein rocker arms and roller levers are independently rotatable and both independently follow the respective associated cam. In the unlocked state, the second cam is ineffective - it actuates the roller lever, but only performs tilting movements, without influencing the valve. On the other hand, in the locked by the locking device state Rocker arm and roller lever rotatably connected to each other, so that both can only be pivoted together about the rocker arm axis.

A particular advantage of the valve drive according to the invention lies in the compact design, which does not or at least hardly affects the space in height and length of a conventional toggle lever-based valve train. The rocker arm only becomes wider, but moves in the size range of a conventional two-valve rocker arm. Characterized in that the roller lever is pivotally mounted directly on the rocker arm, the rocker arm assembly of rocker arm and roller lever can be pre-assembled as a unit, whereby the assembly costs can be reduced. Likewise, the invention makes it possible to convert an existing valve train without variability, without requiring changes to surrounding components, apart from those which are needed directly for the realization of the variability. Another advantage is in particular that no changes to the cylinder head are necessary if a conventional non-variable rocker arm valve drive is to be replaced by the variable valve train according to the invention.

According to a preferred embodiment, on both sides of the first cam - seen in the longitudinal direction of the camshaft - each provided a second cam, d. H. a cam with a different from the middle first cam cam contour. Accordingly, the roller lever is formed so that it has two arms which extend on both sides of the camshaft-side end of the rocker arm and tap the cam contour of the two second cam. The two arms engage their associated second cam each with a roller, z. B. a pressure roller from, which rolls on the second cam. This two-armed embodiment of the roller lever allows an advantageous power flow to transmit the cam movement of the second cam in the activated state of the hydraulic locking device via the roller lever on the rocker arm and the rocker arm to the lift valve.

According to an alternative embodiment may be provided on both sides of the second cam ever a first cam and the camshaft side end of the rocker arm extend on both sides of the roller lever and tap the cam contour of the two first cam. In this alternative embodiment, the camshaft end of the rocker arm thus has two arms, wherein the roller lever is arranged therebetween. The two arms grasp their associated first cam each with a roller, z. B. a pressure roller from, which rolls on the first cam.

According to a first alternative of the invention, the roller lever is connected to the rocker arm via a hinge for rotatably securing the roller lever to the rocker arm about the rocker arm axis. According to a second alternative of the invention, the rocker arm and the roller lever each have a hinge pin receptacle, which are arranged in alignment with each other and have an inserted hinge pin.

A further advantageous possibility of the realization according to the invention provides that the rocker arm and the roller lever are clamped together by at least one return spring, such that the rollers of roller lever and rocker arm are aligned in a base circle position to each other. In other words, the roller lever is pressed by the return spring permanently to the main rocker arm while the camshaft is in a base circle position.

These return springs preferably press on a contact point on or of the rocker arm and on a contact point on or of the roller lever. Due to the mutual tension easy pre-assembly of the entire switchable rocker arm is possible. It when two such return springs - seen in the longitudinal direction of the rocker arm - are arranged on both sides of the rocker arm is particularly advantageous.

According to a preferred embodiment, the switchable hydraulic locking device comprises a hydraulically actuable shift pin, which can be brought from a first position (release position) in a second position (locking position) by applying a predetermined hydraulic pressure. In the second position, the shift pin prevents a relative movement of the rocker arm to the roller lever to each other about the Kipphebelachse, d. h., In the second position, the roller lever can not be pivoted independently of the rocker arm about the tilt axis. In the first position of the shift pin allows a relative movement of the rocker arm and the roller lever to each other. In the second position, the rocker arm and the roller lever are hydraulically locked, but not in the first position.

According to an advantageous variant of this embodiment are in the rocker arm in a Gleitführungsbohrung the rocker arm, a guide pin, a plugged onto the guide pin bolt spring and the shift pin of the hydraulic Verrieglungseinrichtung, which is bolted to the guide pin arranged. The switching pin is on one for actuation the circuit can be filled with oil-filled pressure chamber with a predetermined oil pressure.

In this case, the locking direction can be designed according to a first variant so that the switching pin is held in a state not acted upon by the predetermined pressure by acting as a return spring bolt spring and the guide pin in the first position and in a state acted upon by the predetermined pressure in the second position is pressed, in which the switching pin protrudes from the rocker arm in the direction of the roller lever and moves into an aligned Gleitführungsaufnahme the roller lever.

In this case, the locking direction can be further designed according to a second variant, that the switching pin is held in a state not acted upon by the predetermined pressure by the bolt spring in the second position (locking position), so that roller lever and rocker arms are locked together rotatably and in one pressed state with the predetermined pressure are pressed into the first position in which the shift pin is sunk into the rocker arm and the two levers are unlocked from each other.

The Gleitführungsaufnahme the roller lever is designed to be open, so that the compressed by the retraction of the shift pin compressed air can escape and does not resist the extension movement of the shift pin. This opening is already provided in the blank of the roller lever, so that no additional vent hole is needed.

The rocker arm can on its underside, d. H. the cylinder head facing side, have a geometry for axial fixation on a bearing block. For example, the rocker arm may have a mounting for attachment to a Kipphebellagerbock on which the rocker shaft is arranged, on which the rocker arm with an associated bore is pivotally mounted and held by an axial position assurance, wherein the axial position securing a guide connection as an engagement element counter-element connection between the bearing block and the rocker arm, in which a transversely aligned to the axial direction engagement element, for. B. in the form of an annular web, engages pivotally in an associated counter element with axial flank support.

Another aspect of the invention relates to a motor vehicle, in particular a commercial vehicle, with a variable valve train, as described in this document.

Figur 1

eine perspektivische Vorderansicht eines Ventiltriebs gemäß einer Ausführungs-form der Erfindung;

Figur 2

eine perspektivische Seitenansicht eines Ventiltriebs gemäß einer Ausführungs-form der Erfindung;

Figur 3

eine perspektivische Unteransicht eines Ventiltriebs gemäß einer Ausführungs-form der Erfindung;

Figur 4

eine Seitenansicht eines Kipphebels gemäß einer Ausführungsform der Erfindung; und

Figur 5

einen Schnitt A-A durch Figur 4.

The preferred embodiments and features of the invention described above can be combined with one another as desired. Further details and advantages of the invention will be described below with reference to the accompanying drawings. Show it:

FIG. 1

a front perspective view of a valve train according to an embodiment of the invention;

FIG. 2

a side perspective view of a valve train according to an embodiment of the invention;

FIG. 3

a perspective bottom view of a valve train according to an embodiment of the invention;

FIG. 4

a side view of a rocker arm according to an embodiment of the invention; and

FIG. 5

a cut AA through FIG. 4 ,

Identical parts are provided in the figures with the same reference numerals, so that the different views of the valve train shown in the figures are also self-explanatory.

The FIGS. 1 to 3 show various perspective views of a variable valve train 1 according to an embodiment of the invention. The valve train 1 is used to actuate a charge exchange valve (not shown) of an internal combustion engine which is periodically movable between a closed and an open position by a cam via a rocker arm.

The camshaft 7 has a central cam 3, also referred to as first cam in this document, and two further cams 4, 5 arranged staggered in the longitudinal direction of the camshaft 7. These cams 4, 5 are also referred to as second cams in this document , The two cams 4, 5 are arranged on both sides of the central cam and adjacent to this. The central cam 3 and the two second cams 4, 5 are designed differently in their cam contour. The second cams 4, 5 have a larger cam lift than the middle cam 3.

Furthermore, the phase angle of the central cam 3 with respect to the second cam 4, 5 may differ. Depending on the application, the first cam may also be designed as a zero cam, so that the valves remain closed.

Of the two cam contours in a switching state only one of the decisive for the valve movement, which will be explained below.

The valve train further comprises a rocker arm assembly comprising a rocker arm 10 pivotably mounted about a rocker shaft 2 and associated with its camshaft end 11 via a pressure roller 13 of the first cam 3 for tapping it and at its valve end 12 in operative communication with at least one Lift valve is stopped.

The rocker arm 10 is mounted on a rocker arm bearing block (not shown), wherein the rocker arm 2 is disposed on the rocker arm bearing block, on which the rocker arm 10 is pivotally mounted with an associated bore and held by an axial position assurance.

The axial position assurance can be done for example in a conventional manner via contact surfaces on the Kipphebelflanken. These flanks can be created for example by calibration of the forging blank or by mechanical processing. Bearing side, the fixation can also be done on appropriately machined surfaces and by means of washers and retaining rings. Next axial position locks between a rocker arm and the axle are known. For example, has an area of the axis, which is enclosed by the bore of the rocker arm, an annular groove in which a snap ring extends, which runs at the same time with its outer ring portion in an annular groove of the rocker arm

In the present embodiment, the axial position assurance is designed as an engagement element counter-element connection between the bearing block and the rocker arm, wherein a transversely aligned to the axial direction engagement element, for. B. in the form of an annular web 16, in an associated counter-element (not shown) engages pivotally with axial flank support.

The valve-side lever arm 12 of the rocker arm 10 is designed as a two-valve lever arm to actuate two charge exchange valves simultaneously. For this purpose, the valve-side lever arm 12 is fork-shaped. At each valve-side end of the lever arm 12 is a Recording 15 arranged. The receptacle 15 can be used for mounting a known hydraulic valve lash adjuster element (not shown). Instead of a hydraulic valve clearance compensation element, a screw with elephant foot can be accommodated in the receptacle 15, by means of which a valve clearance can be readjusted manually.

Hydraulic valve clearance compensation elements (HVA) in internal combustion engines are known per se and serve, in particular, to compensate for the change over the operating length length dimensions of the charge exchange valves so that in the base circle phase of the valve-actuating cam secure valve closing is ensured. On the other hand, the cam lobe should be transferred without loss to the valve and thus converted into a valve lift. The operation of such hydraulic valve clearance compensation elements, which are arranged in the power flow of a valve control, in particular an internal combustion engine, is assumed to be known.

To form a variable valve train, the valve train 1 further comprises a roller lever 20, which is assigned to the two second cams 4, 5 at its camshaft-side end 21 and is pivoted at its other end to the rocker arm 10 about the rocker shaft 2.

The rocker arm 10 is connected via a hinge pin 25 rotatably connected to the roller lever 20. For this connection is located on the rocker arm 10 is a hinge pin receptacle 14 and the roller lever 20 is a hinge pin receptacle 24. The mutually aligned hinge pin receptacles 14, 24 are on an upper side, d. H. a side facing away from the cylinder head, the rocking lever 10, and that at a central region of the rocker arm 10, which forms the cylindrical recess of the rocker arm, in which the rocker shaft 2 is received.

The camshaft side lever arm 11 of the rocker arm 10 carries at its end a pressure roller 13 which is associated with the central cam 3 to tap the cam 3 and its rotational movement.

The roller lever has two to the camshaft / down extending, parallel arms 21, which also - in the longitudinal direction of the camshaft / seen - on different sides of the camshaft side lever arm 11 of the rocker arm 10 extend.

Each of the two arms 21 also carries at the end a pressure roller 23. Each of the pressure rollers 23 is one of the two second cams 4, 5 assigned to tap these.

Both the rocker arm 10 and the roller lever 20 are thus rotatably mounted to the rocker shaft 2 and independently pivotable to the rocker arm axis - at least when rocker arm 10 and roller lever 20 are not locked together by the switchable hydraulic locking device.

The rocker arm 10 and the roller lever 20 are further clamped together via two return springs 6 fastened on both sides, so that the roller lever 20 is permanently pressed against the rocker arm 10, while the camshaft / is in a base circle position. In this context, a basic circle phase or cam base circle phase is to be understood as meaning, in particular, an angular range of the cam unit in which cam contours of all partial cams of the cam unit occupy a common base circle level.

These return springs 6 press on the contact point 17 of the rocker arm 10 (see FIG. 3 ) as well as against the contact point 27 of the roller lever 20 (see FIG. 1 or 2 ). Due to the mutual tension pre-assembly of the entire switchable rocker arm assembly 10, 20 is possible.

The variable valve train 1 further comprises a switchable hydraulic locking device or a hydraulic switching element 30, are locked by the rigidly with each other when switching the rocker arm 10 and the roller lever 20 and both of the movement of the second cam 4, 5 follow.

In the rocker arm 10, this is the switchable hydraulic locking device 30, whose structure based on the FIGS. 4 and 5 is explained in more detail.

The switchable hydraulic locking device 30 comprises a guide pin 34, on which a bolt spring 33 is attached. The guide pin 34 and the bolt spring 33 are located in a Gleitführungsbohrung 37, which is introduced into the camshaft-side lever arm 11 of the rocker arm 10. In the Gleitführungsbohrung 37 of the guide pin 34 is screwed to a shift pin 31. The bolt spring 34 comes to a spring stop 32 to the plant. The switching pin 31 also has a zero point system 36. In a basic state (no pressurization), the switching pin 31 is pressed by the bolt spring 33 to the zero point system 36. Behind the switching pin 31 is a pressure chamber 35, which is filled to actuate the circuit with oil. By the Oil pressure in the pressure chamber 35, the shift pin 31 is pushed out with the bolted guide pin 34, so that the bolt spring 33 is compressed. In this case, the guide pin 34 comes to stop on the contact surface 38, so that a defined end position in the extended state of the two bolts 31, 34 is given.

In this extended state of the shift pin 31 this protrudes from the Kipphebelarm 11 out - in the direction of an adjacent arm 21 of the roller lever 10 - and engages in a flush provided Gleitführungsaufnahme (not shown) of the roller lever 10 a. As a result, the shift pin 31 locked in the extended state, the rocker arm 10 with the roller lever. In this state, rocker arm 10 and roller lever 20 are no longer independently pivotable about the rocker shaft 2, but only together. In this locked state follow the rocker arm 10 and the roller lever 20 of the cam contour of the second cam 4, 5, since they have the larger stroke.

Lets the oil pressure, the shift pin 31 together with guide pin 34 is pressed by the spring force of the bolt spring 33 again against the zero point system 36, and the roller lever 20 is decoupled again from the rocker arm 10.

Rocker arm 10 and roller lever 20 are thus rotatably supported independently of each other about the Kipphebelachse 2 when not switched hydraulic locking direction 30, so that the second cam 4, 5 are ineffective, d. that is, the second cams 4, 5 actuate the roller lever 20, but only performs tilting movements, without influencing the valve. In contrast, the rocker arm and roller lever are rotatably connected to each other when the locking direction is switched on, so that both can only be pivoted together about the rocker shaft axis 2.

By selectively pressurizing the pressure chamber 35 with a hydraulic pressure can thus at a desired time, for. As a function of operating parameters, from the first cam contour of the central cam 3 to an alternative cam contour of the second cam 4, 5 are switched and vice versa, to operate the gas exchange valves of the engine variable with different opening and closing times and / or with different valve opening strokes ,

LIST OF REFERENCE NUMBERS

1

valve train

2

rocker shaft

3

First cam, z. B. middle cam

4, 5

Second cam

6

Return spring

7

camshaft

10

rocker arm

11

Camshaft side lever arm

12

Valve side lever arm

13, 23

pressure roller

14, 24

Wrist pin receiving

15

admission

16

ring land

17, 27

Mooring for return spring

20

roller lever

21, 22

lever arm

23

Mooring for return spring

25

pintle

30

Hydraulic locking device

31

switching pin

32

spring stop

33

pin spring

34

guide pins

35

pressure chamber

36

Zero conditioning

37

Gleitführungsbohrung

38

contact surface

Claims (10)

1. Variable valve train (1) for a lifting valve, in particular for a gas exchange valve of an internal combustion engine, which valve can be moved periodically indirectly by way of a cam via a rocker arm between a closed and an open position, comprising

   (a) a camshaft (7), having at least one first cam (3) and at least one second cam (4, 5) which is arranged offset in the longitudinal direction of the camshaft (7), the at least one first cam (3) and the at least one second cam (4, 5) being of different design in terms of their cam contour;

   (b) a rocker arm (10) which is mounted such that it can be pivoted about a rocker arm axis (2), which rocker arm (10) is assigned to the at least one first cam (3) via a roller (13) at its camshaft-side end (11) and is operatively connected to at least one lifting valve at its valve-side end (12);

   (c) a roller lever (20) which is assigned to the at least one second cam (4, 5) via at least one roller (23) at its camshaft-side end (21) and is articulated at its other end on the rocker arm (10) such that it can be pivoted about the rocker arm axis (2),

   (d) a switchable hydraulic locking device (30), by way of which the rocker arm (10) and the roller lever (20) can optionally

   (d1) be locked rigidly to one another, both following the movement of the at least one second cam (4, 5), or

   (d2) be unlocked from one another, both following the respectively associated cams (3, 4, 5) independently of one another,

   characterized

   (a) in that the roller lever (20) is connected to the rocker arm (10) via a hinge (14, 24, 25); and/or

   (b) in that the rocker arm (10) and the roller lever (20) in each case have a pivot pin seat (14, 24), which pivot pin seats (14, 24) are aligned with respect to one another and have an inserted pivot pin (25).
2. Variable valve train (1) according to Claim 1, characterized in that

   (a) in each case one second cam (4, 5) is provided on both sides of the first cam (3), and the roller lever (20) extends on both sides from the camshaft-side end (11) of the rocker arm (10) and follows the cam contour of the two second cams (4, 5), or

   (b) in each case one first cam (3) is provided on both sides of the second cam (4, 5), and the camshaft-side end of the rocker arm (10) extends on both sides from the roller lever (20) and follows the cam contour of the two first cams (3).
3. Variable valve train (1) according to one of the preceding claims, characterized in that the rocker arm (10) and the roller lever (20) are braced against one another via at least one restoring spring (6) in such a way that the rollers (13; 23) of the rocker arm (10) and the roller lever (20) are aligned with respect to one another in a base circle position.
4. Variable valve train (1) according to Claim 3, characterized in that two restoring springs (6) of this type are provided which are arranged on different sides of the rocker arm (10) as viewed in the longitudinal direction of the rocker arm axis (2).
5. Variable valve train (1) according to one of the preceding claims, characterized in that the switchable hydraulic locking device (30) comprises a hydraulically actuable switching pin (31) which can be moved from a first position into a second position by way of loading with a predefined hydraulic pressure, the switching pin (31) permitting a relative movement of the rocker arm (10) and the roller lever (20) with respect to one another in the first position, and preventing a relative movement of the rocker arm (10) and the roller lever (20) about the rocker arm axis (2) in the second position.
6. Variable valve train according to Claim 5, characterized in that a guide pin (34), a pin spring (33) which is plugged onto the guide pin (34), and the switching pin (31) which is screwed to the guide pin (34) are arranged in the rocker arm (10) in a sliding guide bore (37), and the switching pin (31) can be loaded with a predefined oil pressure via a pressure chamber (18) which can be filled with oil in order to actuate the switching means, the locking device (30) being configured in such a way that the switching pin (31), in a state in which it is not loaded with the predefined pressure, is held by way of the pin spring (33) which acts as a restoring spring and the guide pin (34)

   (a) in the first position, and that the switching pin (31), in a state in which it is loaded with the predefined pressure, is pressed into the second position, in which the switching pin (31) protrudes out of the rocker arm (10) in the direction of the roller lever (20) and moves into an aligned sliding guide seat of the roller lever (20), or

   (b) is held in the second position, and that the switching pin (31), in a state in which it is loaded with the predefined pressure, is pressed into the first position, in which the rocker arm (10) moves in, with the result that it releases the aligned sliding guide seat of the roller lever (20).
7. Variable valve train according to one of the preceding claims, characterized in that the cam contour of the at least one first cam (3) has a different cam elevation and/or a different phase position in comparison with the cam contour of the at least one second cam (4, 5).
8. Variable valve train according to one of the preceding claims, characterized in that, at its valve-side end (12), the rocker arm (10) has a seat (15), in which a hydraulic valve play compensating element or a screw with an elephant foot formation is received.
9. Variable valve train according to one of the preceding claims, characterized by a bearing system of the rocker arm (10), having a rocker arm bearing block, on which the rocker arm axis is arranged, onto which the rocker arm is plugged pivotably by way of an associated bore and is held by means of an axial positional securing means, the axial positional securing means being a guide connection as engagement element/counterelement connection between the bearing block and the rocker arm, in which an engagement element (16) which is oriented transversely with respect to the axial direction engages into an associated counterelement with axial flank support in a pivotably movable manner.
10. Motor vehicle, in particular commercial vehicle, having a valve train (1) according to one of the preceding claims.

Images