EP3332100B1 - Valve train for an internal combustion engine - Google Patents

Description

With the aid of an adjustable, conventional valve drive which comprises two cams with different cam lifts, the cylinder of an internal combustion engine can be operated in two different operating modes. If only a single cam is used instead of two cams with different lifts and - instead of a second cam - a base circle without cam lift is used, the cylinder can be switched off with the aid of the valve drive. In such a switched-off state, a cam follower coupled to a gas exchange valve of the cylinder does not interact with the single cam, but with said base circle, so that the gas exchange valve is not actuated.

A valve train of the type mentioned is from DE 199 45 340 A1 known. Also from the JP 2014 224496 A , the EP 2 487 341 A1 , the DE 10 2009 005731 A1 , the US 2014/190432 A1 , the WO 2010/136875 A1 and the US 2014/165940 A1 such adjustable valve trains are known.

It is an object of the present invention to show new ways in the development of valve trains.

This object is achieved by a valve drive with all the features of independent claim 1. Preferred embodiments are the subject of the dependent claims.

The basic idea of the invention is accordingly to equip a valve drive with a purely mechanical adjusting device, by means of which the cam follower can be adjusted between a first and a second axial position. This means a considerably simplified structural design of the valve drive, which in turn means a reduced space requirement.

A valve train according to the invention comprises a camshaft and a cam follower. A first cam and, axially adjacent to it, a second cam are attached to the camshaft in a rotationally fixed manner. An axial direction can be defined by the central longitudinal axis of the camshaft. The first cam can be arranged axially at a distance from the first cam or bear against it. The cam follower is axially adjustable along an axial direction. The cam follower is axially adjustable between a first position in which the cam follower is drivingly connected to the first cam and a second position in which the cam follower is drivingly connected to the second cam. According to the invention, the cam follower has a mechanical adjustment device which interacts with the camshaft for the axial adjustment of the cam follower between the first and the second position.

According to the invention, the mechanical adjusting device has an adjustable first mechanical engagement element. For the axial adjustment of the cam follower from the first to the second position, this interacts with at least one first link guide present on the camshaft. The adjusting device also has a second mechanical engagement element that can be produced and which, for the axial adjustment of the cam follower from the second to the first position, interacts with at least one second link guide present on the camshaft. The use of such mechanical engagement elements makes it possible to dispense with technically complex pneumatic systems.

According to a further development, the mechanical adjustment device comprises a first actuator. By means of the first actuator, the first mechanical engagement element can be adjusted between a first position in which it engages the first link guide and a second position in which it can be adjusted does not intervene in the first link guide. Alternatively or additionally, the mechanical adjustment device comprises a second actuator, by means of which the second mechanical engagement element can be adjusted between a first position in which it engages the second link guide and a second position in which it does not engage the second link guide. The use of such actuators makes it possible to dispense with pneumatic and / or hydraulic adjustment means for adjusting the respective engagement element, which can be technically implemented only with considerable effort.

According to the invention, the first actuator can be adjusted between an inactive position and an active position. The adjustability can preferably be implemented such that the first actuator is out of contact with the first engagement element in the inactive position and the first engagement element is moved from the inactive position to the active position through mechanical contact from the second to the first Adjusted position. In this variant, the second actuator can also be adjustable between an inactive position and an active position as an alternative or in addition to the first actuator. Corresponding to the first actuator, the second actuator is also out of contact with the second engagement element in the inactive position. By moving from the inactive position to the active position, the second actuator moves the second engagement element from the second to the first position by mechanical contact. The use of purely mechanical means - in the form of actuators - for adjusting the engagement means simplifies the structure of the entire valve train. This goes hand in hand with considerable cost savings in the manufacture of the valve train.

According to the invention, the first and / or second engagement element is adjusted from the first to the second position with the aid of the lifting movement of the cam follower. In other words, the cam follower is moved towards the two actuators by the lifting movement caused by the first or second cam. If these are in their active position, the lifting movement of the cam follower and thus the respective engagement element pressed the respective engagement element against the respective stationary, ie immovable, actuator in the active position relative to the camshaft, and in this way "shifted" the actuator into its second position. An active adjustment of the first or second engagement element by an active movement of the first or second actuator can be dispensed with in this way. Accordingly, the two actuators can be constructed very simply, which leads to cost advantages in production. In one variant, the adjustment of the first engagement element from the first to the second position can also take place at least partially by means of an active movement of the first actuator from the inactive position to the active position. Alternatively or additionally, the adjustment of the second engagement element from the first to the second position can take place at least partially by means of an active movement of the second actuator from the inactive position to the active position.

In a preferred embodiment, a third cam is present in the valve drive in addition to the first and the second cam, so that the cam follower can be adjusted between a first, a second and a third position. In this variant, there are two first link guides and two second link guides. This allows an optional coupling or drive connection of the cam follower with the first, the second or the third cam.

The two first link guides can expediently be essentially parallel and at a distance from one another on a first link body. In this variant, the two second link guides can be arranged essentially parallel and at a distance from one another on a second link body. The three cams are also arranged axially between the two link bodies. This variant requires particularly little axial installation space.

In an advantageous further development, one of the two first link guides is designed for adjusting the cam follower from the first to the second position. The other first link guide is designed to move the cam follower from the second position to the third position. In an analogous manner, one of the two second link guides is designed for adjusting the cam follower from the third back to the second position. The other, second link guide is designed to adjust the cam follower from the second position back into the first position. Said configuration allows the cam follower to be easily switched between its first, second and third position; in particular, only two adjusting elements and consequently only two actuators are required for this. This is accompanied by cost advantages in the manufacture of the valve train.

In another preferred embodiment, the two link guides are axially adjustable relative to the camshaft and are connected to the cam follower by means of a coupling element. Said coupling is implemented in such a way that an axial movement of the link guides for adjustment between the first and second positions is accompanied by an identical axial movement of the cam follower. A particularly long service life of the mechanical adjustment device is associated with this design variant.

An advantageous development in which the two link guides are formed on at least a sleeve proves to be technically particularly simple to implement. Said sleeve is pushed onto the camshaft in an axially displaceable manner. A variant with a common sleeve for both link guides is particularly preferred because it saves space.

The two link guides, preferably the at least one sleeve, part of a bearing device comprising bearing elements, are particularly useful. The camshaft is rotatably supported by such a bearing device, for example on a housing part of the valve train or on another component of the valve train. This variant is also associated with a reduced space requirement and a reduced weight of the entire valve train.

According to a further advantageous development, the coupling element engages in a recess provided on the sleeve. Technically particularly simple and thus inexpensive to implement is a variant in which the recess, which is preferably implemented as a circumferential groove formed on the outer circumference of the sleeve.

Particularly expediently, the coupling element can be designed like a bolt or pin and protrude radially outward from the cam follower. This variant requires particularly little installation space.

The two actuators can particularly preferably be designed as linearly adjustable, electrically driven actuators. In this case, they can be controlled in a simple manner by a control device of the valve drive for adjusting between the active position and the inactive position. In addition, implementation as electrical actuators allows very precise control of the linear positioning of the actuators along their direction of adjustment. In this variant, the mechanical adjustment device is implemented as an electromechanical adjustment device.

In a further preferred embodiment, the first actuator has a linearly adjustable first adjusting element. This can comprise a cylindrical adjusting body, the end face of which presses against an end face of the engagement element opposite the first adjusting element when the first engagement element is moved into the first link guide. In an analogous manner, the second actuator can also have a linearly adjustable second actuating element which is cylindrical Has adjusting body. Its end face can, in a manner analogous to the first adjusting element, press against an end face of the second engagement element opposite the second adjusting element when the second engagement element is moved into the second link guide. In the manner described above, the desired mechanical coupling of the actuator to the engagement element can be implemented in a simple and thus inexpensive manner.

In a further advantageous development, the first actuator has a housing and a first adjusting element which is translationally adjustable relative to the housing between the first and the second position. In this variant, the second actuator, as an alternative or in addition to the first actuator, can also have a housing and a second adjusting element which is translationally adjustable relative to this housing between the first and the second position. By means of such adjusting elements, which preferably have a pin-like or bolt-like contact section, the necessary mechanical interaction of the actuators with the engagement elements can be implemented in a simple manner in order to bring the engagement elements, preferably positively, into engagement with the link guides.

In an advantageous development of the invention, which requires particularly little installation space, the first and second link guides are formed in a common link body which is arranged axially on the same side of a cam follower role of the cam follower relative to the two cams.

In a further preferred embodiment, the cam follower has a cam follower fixing device for releasably fixing the cam follower in the first or second position. According to this variant, the cam follower fixing device has a spring-loaded cam follower fixing element. In the first position of the cam follower, this engages in a first receptacle provided on the cam follower and in the second position of the cam follower in an am Cam follower provided a second recording. Such a realization of a fixing mechanism for fixing the cam follower allows the cam follower to be reliably fixed in its first or second axial position and yet requires very little installation space.

Particularly preferred, because it is associated with particularly low manufacturing costs, the first receptacle is designed as a first circumferential groove formed on the circumferential side of the cam follower. The second receptacle is designed accordingly as a second circumferential groove arranged axially at a distance from the first circumferential groove on the circumferential side.

For at least one engagement element, preferably for both engagement elements, the cam follower expediently has an engagement element fixing device for releasably fixing the engagement element in the first or second position. In this variant, said engagement element fixing device has a spring-loaded fixing element. This is received in the first position of the engagement element in a first receptacle provided on the engagement element. In the second position of the engagement element, the fixing element is received in a second receptacle provided on the cam follower.

The first and / or second engagement element preferably each have a bolt-like or pin-like base body, on the circumferential side of which the first receptacle is designed as a first circumferential groove and the second receptacle is designed as an axially spaced second circumferential groove.

In a preferred variant, the mechanical adjustment device does not include any hydraulic and / or pneumatic components.

If the valve drive in an internal combustion engine is to be operated with a cylinder that can be switched off, it is proposed according to a preferred embodiment, the first or second cam is to be designed as a base circle without a cam lift.

The invention further relates to an internal combustion engine with a valve drive presented above.

Further important features and advantages of the invention emerge from the subclaims, from the drawings and from the associated description of the figures on the basis of the drawings.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the respectively specified combination, but also in other combinations or alone, without departing from the scope of the present invention.

Preferred exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description, with the same reference symbols referring to the same or similar or functionally identical components.

Fig. 1

ein Beispiel eines erfindungsgemäßen Ventiltriebs mit einer Nockenwelle, die in einer ersten Axialposition angeordnet ist,

Fig. 2

den Ventiltrieb der Figur 2 mit der Nockenwelle in einer zur ersten Axialposition axial verschobenen, zweiten Position,

Fig. 3

eine erste Variante des Ventiltriebs der Figuren 1 und 2 mit zwei auf einem gemeinsamen Kulissenkörper angeordneten Kulissenführungen.

Fig. 4

eine erste Variante des Ventiltriebs der Figuren 1 und 2 mit einer relativ zur Nockenwelle verstellbaren Hülse, auf welcher die Kulissenführungen angeordnet sind,

Fig. 5

eine zweite Variante des Ventiltriebs der Figuren 1 und 2 mit drei Nocken,

Fig. 6, 7

eine Weiterbildung des Ventiltriebs der Figuren 1 bis 5.

They show, each schematically:

Fig. 1

an example of a valve drive according to the invention with a camshaft which is arranged in a first axial position,

Fig. 2

the valve train of the Figure 2 with the camshaft in a second position axially displaced from the first axial position,

Fig. 3

a first variant of the valve train of the Figures 1 and 2 with two link guides arranged on a common link body.

Fig. 4

a first variant of the valve train of the Figures 1 and 2 with a sleeve which is adjustable relative to the camshaft and on which the link guides are arranged,

Fig. 5

a second variant of the valve train of the Figures 1 and 2 with three cams,

Figures 6, 7

a development of the valve train of the Figures 1 to 5 .

The Figures 1 and 2 illustrate in a schematic representation an example of a valve drive 1 according to the invention. The valve drive 1 comprises a camshaft 2 and a cam follower. A first cam 4a is attached to the camshaft 2 in a rotationally fixed manner. A second cam 4b is arranged axially adjacent to the first cam 4a on the camshaft 2, likewise non-rotatably with respect to this.

In the example of the figures, the first cam 4a is designed as a base circle without a cam lift. This allows the valve drive 1 to be used in an internal combustion engine with a cylinder that can be switched off.

The cam follower is adjustable along an axial direction A between a first position, in which it is drivingly connected to the first cam 4a, and a second position, in which it is drivingly connected to the second cam 4b. Figure 1 shows the cam follower in said first position, the Figure 2 shows the cam follower in its second position. The cam follower can have a cylindrical cam follower base body 5 whose circumferential side is a hollow cylindrical cam follower roller 6 is rotatably mounted. The cam follower base body 5 is also known to the person skilled in the art under the designation “bolt” or “displacement axis”. The drive connection of the two cams 4a, 4b to the cam follower takes place in a known manner via the cam follower roller 6. The rotary movement of the camshaft 2 is converted into a linear movement of the cam follower by means of the cams 4a, 4b.

In the in Figure 1 The cam follower roller 6 is coupled to the first cam 4a shown in the first position of the cam follower shown in FIG Figure 2 with the second cam 4b. The cam follower roller 6 controls (not shown) via a suitably designed mechanical coupling device, in particular in the form of an actuator, a valve for adjusting between an open and a closed state. Concrete technical implementation options for such a coupling are not part of the present invention, but are known to the relevant person skilled in the art from the prior art in various forms, so that a more detailed explanation in this regard can be dispensed with.

The cam follower of the Figure 1 has a mechanical adjusting device 7 which interacts with the camshaft 2 for the axial adjustment of the cam follower between the first and the second position. For this purpose, the mechanical adjusting device 7 comprises a first adjustable mechanical engagement element 8a. The first mechanical engagement element 8a acts to axially adjust the cam follower from FIG Figure 1 The first position shown in the second position with a first link guide 9a present on the camshaft 2 together. In an analogous manner, the mechanical adjusting device 7 has an adjustable second mechanical engagement element 8b. The second engagement element 8b interacts with a second link guide 9b present on the camshaft for the axial adjustment of the cam follower from its second to the first position.

A hardened steel can be used as the material for the camshaft 2, which can be surface-hardened, in particular nitrided, in the area of the two link guides.

The mechanical adjustment device 7 further comprises a first actuator 10a, by means of which the first engagement element 8a between an in Figure 1 first position shown, in which it engages in the first link guide 9a, and one in Figure 2 second position shown is adjustable, in which it does not engage in the first link guide 9a. The mechanical adjustment device 7 also comprises a second actuator 10b, by means of which the second engagement element 8b can be adjusted between a first position in which it engages the second link guide 9b and a second position in which it does not engage in said second link guide 9b.

The first actuator 10a can be adjusted between an inactive position and an active position. For this purpose, the two actuators 10a, 10b can be designed as linearly adjustable, electrically driven actuators. The mechanical adjusting device 7 is implemented as an electromechanical adjusting device in this case. In other words, electrically driven actuators 10a, 10b are encompassed by the term “mechanical control device” 7 in the present case.

The two actuators 10a, 10b can be controlled by a control device 11 of the valve drive 1 for adjustment between their active position and their inactive position. This adjustability is realized such that the first actuator 10a is out of contact with the first engagement element 8a in the inactive position. In the course of an adjustment from its inactive position to its active position, the first actuator 10a adjusts the first engagement element 8a from its second to its first position by mechanical contact.

The adjustment of the first engagement element 8a from the first to the second position can preferably be effected by means of the lifting movement of the cam follower, in particular by means of the cam follower base body 5. The cam follower is moved in the direction of the first actuator 10a by the stroke movement caused by the first or second cams 4a, 4b. If the latter is in its active position, the lifting movement of the cam follower and thus of the first engagement element 8a press the latter against the first actuator 10a and move it into its second position.

In one variant, the adjustment of the first engagement element 8a from the first to the second position can also take place while executing a synchronized active movement of the first actuator 10a from the inactive position to the active position.

In this state, the first engagement element 8a engages in the first link guide 9a, so that the cam follower is moved axially from its first to the second position due to the rotary movement of the camshaft 2 with the aid of the first link guide 9a arranged thereon. The second actuator 10b can also be adjusted between an inactive position and an active position. This adjustability is realized such that the second actuator 10b is out of contact with the second engagement element 8b in the inactive position. In the course of an adjustment from its inactive position to its active position, the second actuator 10b adjusts the second engagement element 8b from its second to its first position by mechanical contact.

The adjustment of the second engagement element 8b from the first to the second position is also preferably effected by means of the lifting movement of the cam follower, in particular by means of the cam follower base body 5. The cam follower is moved in the direction of the second actuator 8b by the lifting movement caused by the first or second cams 4a, 4b. If this is in its active position, Thus, by the lifting movement of the cam follower and thus of the second engagement element 8b, the latter is pressed against the second actuator 10b and thus displaced by the latter into its second position. In a variant, the adjustment of the second engagement element 8b from the first to the second position can also take place while executing a synchronized active movement of the first actuator 10a from the inactive position to the active position.

In this state, the second engagement element 8b engages in the second link guide 9b, so that the cam follower is moved axially from its second to the first position due to the rotary movement of the camshaft 2 with the aid of the second link guide 9a arranged on it.

The first actuator 10a has a linearly adjustable (cf. arrow 15a) first adjusting element 12a. This can partially protrude from a first housing 16a of the first actuator 10a and be arranged linearly adjustable relative to this. An end face 13a of the first actuating element 12a facing the first engagement element 8a, which can be designed like a pin or bolt, presses against an end face 14a of the first engagement element 8a opposite the first actuating element 12a when the first engagement element 8a is moved into the first link guide 9a. The second actuator 10b has a linearly adjustable (cf. arrow 15b) second adjusting element 12b. This can partially protrude from a second housing 16b of the second actuator 10b and be arranged linearly adjustable relative to this. A face 13b of the second actuating element 12b facing the second engagement element 8b, which can be designed like a pin or bolt, presses when the second engagement element 8b is moved into the second link guide 9b against an end face 14b of the second engagement element 8b opposite the second actuating element 12b.

Like the representation of the Figure 2 can be seen, the cam follower also has a cam follower fixing device 17 for releasably fixing the cam follower in FIG the first or second position. The cam follower fixing device 17 comprises a spring-loaded cam follower fixing element 18. The cam follower fixing element 18 engages in a first receptacle 19a provided on the cam follower in the first position of the cam follower and engages in a second receptacle 19b provided on the cam follower in the second position of the cam follower on. The first receptacle 19a is preferably as in FIG Figure 2 realized as a first circumferential groove 20a, which is arranged on a circumferential side 21 of the cam follower. The second receptacle is implemented accordingly as a second circumferential groove 20b arranged axially at a distance on the circumferential side 21.

As the Figures 1 and 2 As can be clearly seen, the cam follower for the two engagement elements 8a, 8b, preferably for both engagement elements 8a, 8b, each has a first and second engagement element fixing device 22a, 22b for releasably fixing the first and second engagement element 8a, 8b in the first or second engagement element second position. It can be seen that the two engagement element fixing devices 22a, 22b each have a spring-loaded fixing element 23a, 23b, which in the first position of the respective engagement element 8a, 8b is received in a first receptacle 24a, 24b provided on the respective engagement element 8a, 8b. In the second position of the cam follower, the fixing element 23a, 23b is received in a second receptacle 25a, 25b provided on the cam follower. The first and the second engagement element 8a, 8b each have a bolt-like or pin-like base body 29a, 29b. On a circumferential side of the base body 29a, 29b, the first receptacle 24a, 24b is designed as a first circumferential groove 27a, 27b and the second receptacle 25a, 25b as a second circumferential groove 28a, 28b arranged axially at a distance on the circumferential side.

The following is based on the representation of the Figures 1 and 2 an adjustment of the cam follower from the first to the second position explained. In the scenario of the character 1, the cam follower is in the first position, in which its cam follower roller 6 is drivingly connected to the first cam 4a.

If the cam follower is to be adjusted from its first to its second axial position, the first engagement element 8a of the mechanical adjustment device 7 is as in FIG Figure 1 shown brought into engagement with the first link guide 9a. This is done with the aid of the first electrical actuator 10a.

As already explained, the first actuator 10a is between one in Figure 1 shown inactive position and an active position - in Figure 1 indicated by dashed lines adjustable. In the inactive position, the first actuator 10a is mechanically out of contact with the first engagement element 8a. In the course of an adjustment from its inactive position to its active position, the first actuator 10a adjusts the first engagement element 8a from its second to its first position by mechanical contact. In the first position, the first engagement element 8a engages in the first link guide 9a (cf. Figure 1 ), so that the cam follower is moved axially from its first to its second position by the rotary movement of the camshaft 2 with the aid of the first link guide 9a, which is shown in Figure 2 is shown. After the first engagement element 8a has been brought into engagement with the first link guide 9a, the first actuator 10a can be moved back into its inactive position by the control device 11.

The first link guide 9a can - like the second link guide 9b - have a ramp structure, not shown in the figures, such that the first engagement element 8a is disengaged from the first link guide as soon as the cam follower has reached the second axial position. In this second position, the second cam 4b is in drive connection with the cam follower roller 6. The adjustment of the cam follower from the second position back to the first position can be done with the help of the second actuator 10b, the second engagement element 8b and the second link guide 9b in a manner analogous to previously explained transition from the first to the second position of the cam follower take place.

In a variant not shown in detail in the figures, the valve drive can also be designed in such a way that not the entire cam follower but only the cam follower role of the cam follower is axially adjusted between the first and the second position.

The link guides 9a, 9b can each be formed on a first or second sleeve 42a, 42b. At least one of the two sleeves 42a, 42b - in the example of Figures 1 and 2 the second sleeve 42b can be part of a bearing device 46. The storage device 46 comprises in the Figures 1 and 2 Conventional bearing elements 47a, 47b, indicated only roughly schematically, by means of which the camshaft 2 is rotatably supported on a housing (not shown) or another stationary component of the valve drive 1.

In Figure 3 is a variant of the example of the Figures 1 and 2 shown. The valve train 1 of the Figure 3 differs from that of the Figures 1 and 2 in that the first and second link guides 9a, 9b are formed axially on the same side in a common link body 26 relative to the two cams 4a, 4b. It is clear that this is accompanied by a change in the axial arrangement of the two engagement elements 8a, 8b and the two link guides 9a, 9b and the two actuators 10a, 10b. The variant of the Figure 3 requires very little installation space in the axial direction A.

In Figure 4 is another variant of the example of the Figures 1 and 2 shown, where in Figure 4 the camshaft 2 and the cam follower are shown only in an axial partial section for the sake of clarity. With the variant according to Figure 4 are the two link guides 9a, 9b relative to the camshaft 2 axially adjustable mounted on this and by means of a coupling element 41 with the Cam follower connected. Said coupling is implemented in such a way that a movement of the link guides 9a, 9b along the axial direction A for adjusting the cam follower between the first and second positions is also accompanied by an axial movement of the cam follower. The coupling element 41 is as in FIG Figure 4 shown is bolt-like or pin-like and protrudes radially outward from the cam follower. As the Figure 4 As can further be seen, the two link guides 9a, 9b are designed as outer circumferential grooves 45a, 45b on a common sleeve 42. Said sleeve 42 is axially displaceable (see arrow 20 in Figure 4 ) pushed onto camshaft 2. In this way, the coupling element 41 for mechanical axial coupling can engage in a recess 43 provided on the sleeve 42, which as in FIG Figure 4 indicated is preferably realized as a circumferential groove 44 formed on the outer circumference of the sleeve 42. When the sleeve 42 is adjusted along the axial direction A, caused by an engagement of the first engagement element 8a or the second engagement element 8b in the respective link guide 9a, 9b, the cam follower - due to the existing mechanical coupling of the sleeve 42 via the coupling element 41 the cam sequence - taken along the axial direction A. This causes the desired axial adjustment of the cam follower between its first and second position.

The Figure 5 shows a further variant of the example of FIG Figures 1 and 2 , in which on the camshaft 2 not only two cams, but three cams 4a, 4b, 4c are non-rotatably arranged. When valve train 1 of the Figure 5 the cam follower is consequently adjustable between a first, a second and a third position. In the third position of the cam follower, the cam follower roller 6 interacts with the third cam 4c. Nevertheless shows the Figure 5 the cam follower roller 6 in engagement with the second cam 4b.

As Figure 5 further shows, there are not only a single first link guide 9a and a single second link guide 9b in the valve drive 1, but each two first link guides 9a and two second link guides 9b are present. As Figure 5 occupied, the two first link guides 9a are arranged essentially parallel and at a distance from one another on a first link body 40a. Likewise, the two second link guides 9b are arranged essentially parallel and at a distance from one another on a second link body 40b. The three cams 4a, 4b, 4c are arranged axially between the two link bodies 40a, 40b on the camshaft 2. One of the two first link guides (9a) is used to move the cam follower from its first position to its second position. The other first link guide 9a is used to adjust the cam follower from the second position to its third position. In an analogous manner, one of the two second link guides 9b is used to adjust the cam follower from the third position back into the second position. The other second link guide 9b is used accordingly to adjust the cam follower from the second position to the first position.

With the variant according to Figure 5 So it is with the help of only two engagement elements 8a, 8b and only two actuators 10a, 10b, which in an analogous manner to the example Figures 1 and 2 work, possible to adjust the cam follower between the first, the second and the third position using two first and two second link guides 9a, 9b so that the cam follower interacts optionally with the first cam 4a, the second cam 4b or the third cam 4c and is thus connected to the drive.

The Figures 6 and 7 illustrate an advantageous further development of the valve drive 1 when it is used to control valves. The example of the Figures 6 and 7 can with the above using the Figures 1 to 5 illustrated examples.

Figure 6 shows an adjusting lever 30 rotatably mounted on a housing (not shown in detail) about an axis of rotation S in a side view along the axial Direction A. The adjusting lever 30 is adjusted by a movement of the cam follower of the valve drive 1. Two valve bodies 31a, 31b are fixedly attached to the adjusting lever 30. The two valve bodies 31a, 31b close or release a valve opening 32a, 32b assigned to them as a function of the currently set position of the adjusting lever 30. In other words, the two valve bodies 31 a, 31 b can be adjusted between a closed position and an open position by means of the adjusting lever 30. The Figure 6 shows the two valve bodies 31a, 31b in their open position.

The Figure 7 shows the valve train 1 of Figure 6 in a plan view of the two valve openings 32a, 32b. It can be seen that the adjusting lever 30 is designed to be adjustable along the axial direction A and can be adjusted together with the cam follower between a first and a second position. According to the representation of the Figure 7 the adjusting lever 30 has a first lever arm 33a and a second lever arm 33b. The first valve body 31a is arranged on the first lever arm 33a, the second valve body 31b on the second lever arm 33b.

In the in Figure 7 The illustrated first position of the cam follower and the adjusting lever 30 are used, in a known manner, for the two valve bodies 31a, 31b to close or open the two valve openings 32a, 32b. The adjustment of the valve bodies 31a, 31b between their open and closed positions takes place with the aid of the adjusting lever 30 connected to the cam follower, in accordance with the method shown in FIG Figure 6 explained functional principle.

One of the two valve bodies - in the example of Figure 7 the first valve body 31a is designed by suitable dimensioning in such a way that it closes the valve opening 32a in its closed position regardless of whether the cam follower and thus also the actuating lever 30 are in the first or second position. The other valve body - in the example of Figure 7 so the second valve body 31b - is designed such that it has the valve opening 32a in its The closed position only closes when the cam follower and thus the control lever 30 are in the first or, alternatively, in the second position.

In the example of Figure 7 the cam follower and adjusting lever 30 are in the second position, so that in their closed position both valve openings 32a, 32b are closed by valve bodies 31a, 31b. In the example of Figure 7 the first valve body 31a has a greater extent or expansion along the axial direction A than the second valve body 31b.

If the cam follower is now moved axially against the axial direction A - in Figure 7 indicated by arrows denoted by the reference number 34, the two lever arms 33a, 33b and thus also the two valve bodies 31a, 31b are axially adjusted in such a way that after such an adjustment, the first valve body 31a, but not the valve body 31b in its supposed closed position, the second valve opening 32b is able to close.

With the first position set in the cam follower for the two valve bodies 31a, 31b, this scenario is in FIG Figure 7 indicated in dashed lines: The in Figure 7 Axial positions of the valve bodies 31a, 31b, indicated by dashed lines, which correspond to the first position of the cam follower, the valve opening 32b always remains open regardless of the position of the valve body 31b. This proves to be advantageous if the valve drive 1 is used to control the valve bodies 31a, 31b when an engine brake is operated.

the first valve body 31a sits a greater extent or expansion along the axial direction A than the second valve body 31b.

If the cam follower 3 is now moved axially counter to the axial direction A - in Figure 7 indicated by arrows denoted by the reference numeral 34, the two lever arms 33a, 33b and thus also the two valve bodies 31a, 31b are axially adjusted in such a way that after such an adjustment, the first valve body 31a, but not the valve body 31b in its supposed closed position capable of closing the second valve opening 32b.

This scenario is in the case of the first position set in the cam follower 3 for the two valve bodies 31a, 31b in FIG Figure 7 indicated in dashed lines: The in Figure 7 Axial positions of the valve bodies 31a, 31b, indicated by dashed lines, which correspond to the first position of the cam follower 3, the valve opening 32b always remains open regardless of the position of the valve body 31b. This proves to be advantageous if the valve drive 1 is used to control the valve bodies 31a, 31b when an engine brake is operated.

Claims (17)

1. Valve train (1) for an internal combustion engine,

   - comprising a camshaft (2) and a cam follower,

   - as well as a first cam (4a) that is mounted on said camshaft for conjoined rotation and a second cam (4b) that is arranged for conjoined rotation and axially adjacent to said first cam (4a),

   - wherein the cam follower can be axially adjusted between a first position, in which it is drive-connected to the first cam (4a), and a second position, in which it is drive-connected to the second cam (4b),

   - wherein the cam follower has a mechanical, particularly an electromechanical, adjustment device (7) that interacts with the camshaft (2) and axially adjusts the cam follower between the first and the second position,

   - wherein the mechanical adjustment device (7) has an adjustable first mechanical engagement element (8a), which interacts with at least one first slide guide (9a) present on the camshaft (2) for the axial adjustment of the cam follower from the first position into the second position,

   - wherein the mechanical adjustment device has an adjustable second mechanical engagement element (8b), which interacts with at least one second slide guide (9b) present on the camshaft (2) for the axial adjustment of the cam follower from the second position into the first position,

   - wherein the mechanical adjustment device (7) comprises a first actuator (10a), by means of which the first mechanical engagement element (8a) is adjustable between a first position, in which it engages into the first slide guide (9a), and a second position, in which it does not engage into the first slide guide (9a),

   - wherein the mechanical adjustment device (7) comprises a second actuator (10b), by means of which the second mechanical engagement element (8b) is adjustable between a first position, in which it engages into the second slide guide (9b), and a second position, in which it does not engage into the second slide guide (9b),

   - wherein the adjustment of the first engagement element (8a) from the first position into the second position is effected at least in part by means of an active movement of the first actuator (10a) from an inactive position into an active position,

   - wherein the adjustment of the second engagement element (8b) from the first position into the second position is effected at least in part by means of an active movement of the second actuator (10b) from an inactive position into an active position,

   - wherein the first actuator (10a) is adjustable between an inactive position and an active position, such that the first actuator (10a) in the inactive position is not in contact with the first engagement element (8a) and, through an adjustment from the inactive position into the active position, adjusts the first engagement element (8a) through mechanical contact from its second position into its first position,

   - wherein the second actuator (10b) is adjustable between an inactive position and an active position, such that the second actuator (10b) in the inactive position is not in contact with the second engagement element (8b) and, through an adjustment from the inactive position into the active position, adjusts the second engagement element (8b) through mechanical contact from its second position into its first position,

   - wherein the adjustment of the first engagement element (8a) from the first position into the second position is brought about at least in part by means of the stroke movement of the cam follower, in particular of the cam follower base body (5), and/or that

   - wherein the adjustment of the second engagement element (8b) from the first position into the second position is brought about at least in part by means of the stroke movement of the cam follower, in particular of the cam follower base body (5).
2. Valve train according to claim 1,
   characterised in that

   - a third cam (4c) is present in addition to the first and second cams (4a, 4b), so that the cam follower is adjustable between a first, a second and a third position,

   - two first slide guides (9a) and two second slide guides (9b) are present.
3. Valve train according to claim 2,
   characterised in that

   - the two first slide guides (9a) are disposed, preferably substantially parallel, at a distance from one another on a first slide body (40a),

   - the two second slide guides (9b) are disposed, preferably substantially parallel, at a distance from one another on a second slide body (40b),

   - the three cams (4a, 4b, 4c) are disposed axially between the two slide bodies (40a, 40b).
4. Valve train according to claim 2 or 3,
   characterised in that

   - one of the two first slide guides (9a) is configured to adjust the cam follower from the first position into the second position and the other first slide guide (9a) is configured to adjust the cam follower from the second position into the third position,

   - one of the two second slide guides (9b) is configured to adjust the cam follower from the third position into the second position and the other second slide guide (9b) is configured to adjust the cam follower from the second position into the first position.
5. Valve train according to any of the preceding claims,
   characterised in that
   the two slide guides (9a, 9b) are arranged on the camshaft (2) and are axially adjustable relative to the camshaft (2) and are coupled to the cam follower by means of a coupling element (41), so that an axial movement of the cam follower accompanies an axial movement of the slide guides (9a, 9b) for adjustment of the cam follower between the first and second position.
6. Valve train according to claim 5,
   characterised in that
   the two slide guides (9a, 9b) are configured, preferably as external circumferential grooves (45a, 45b), on at least one sleeve (42, 42a, 42b), which is pushed displaceably onto the camshaft (2) along the axial direction (A).
7. Valve train according to claim 6,
   characterised in that
   the two slide guides (9a, 9b), in particular the at least one sleeve (42, 42a, 42b), are part of a bearing device (46) comprising bearing elements (47a, 47b), by means of which the camshaft (2) is rotatably mounted.
8. Valve train according to claim 6 or 7,
   characterised in that

   - the coupling element (41) engages into a recess (43) provided on the sleeve (42), said recess being realised preferably as circumferential groove (44) configured on the external circumference of the sleeve (42), and/or that

   - the coupling element (41) is configured in the manner of a bolt or in the manner of a pin and protrudes radially outwards from the cam follower.
9. Valve train according to any of the preceding claims,
   characterised in that
   the two actuators (10a, 10b) are configured as electrically or hydraulically or pneumatically driven actuators, which are controllable preferably from an electronic control device (11) of the valve drive (1) for adjustment between the active position and the inactive position.
10. Valve train according to any of the preceding claims,
    characterised in that

    - the first actuator (10a) has a linearly adjustable first control element (12a), the face side (13a) of which presses against a face side (14a) of the first engagement element (8a) facing the first control element (12a) when the first engagement element (8a) moves into the first slide guide (9a),

    - the second actuator (10b) has a linearly adjustable second control element (12b), the face side (13a) of which presses against a face side (14b) of the second engagement element (8b) facing the second control element (12b) when the second engagement element (8b) moves into the second slide guide (9b).
11. Valve train according to any of the preceding claims,
    characterised in that
    the first and second slide guides (9a, 9b) are disposed axially on the same side in a common slide body (26) relative to the two cams (4a, 4b).
12. Valve train according to any of the preceding claims,
    characterised in that
    the cam follower has a cam follower fixing device (17) for detachable fixing of the cam follower in the first or second position,
    wherein the cam follower fixing device (17) has a spring-loaded cam follower fixing element (18), which, in the first position of the cam follower, engages into a first mount (19a) provided on the cam follower and, in the second position of the cam follower (3), engages into a second mount (19b) provided on the cam follower.
13. Valve train according to claim 12,
    characterised in that
    the first mount (19a) is configured as first circumferential groove (20a) disposed on the circumferential side (21) of the cam follower and the second mount (19b) is configured as second circumferential groove (20b) disposed axially at a distance on the circumferential side (21).
14. Valve train according to any of the preceding claims,
    characterised in that
    the cam follower has an engagement element fixing device (22a, 22b) for detachable fixing of the engagement element (8a, 8b) in the first or second position for at least one engagement element (8a, 8b), preferably for both engagement elements (8a, 8b),
    wherein the engagement element fixing device (22a, 22b) has a spring-loaded fixing element (23a, 23b), which, in the first position of the engagement element (8a, 8b), is accommodated in a first mount (24a, 24b) provided on the engagement element (8a, 8b) and, in the second position of the engagement element (8a, 8b), is accommodated in a second mount (25a, 25b) provided on the cam follower.
15. Valve train according to claim 14,
    characterised in that
    the first and/or second engagement element (8a, 8b) have respectively a base body (29a, 29b) configured in the manner of a bolt or pin, on the circumferential side of which the first mount (24a, 24b) is configured as first circumferential groove (27a, 27b) and the second mount (25a, 25b) is configured as second circumferential groove (28a, 28b) disposed axially at a distance.
16. Valve train according to any of the preceding claims,
    characterised in that
    the cam follower interacts with a control lever (30) having two lever arms (33a, 33b),
    wherein the control lever (30) is configured such that, in the first axial position of the cam follower, two valve openings (32a, 32b) are optionally open or closed through rotational adjustment of the two lever arms (33a, 33b), depending on the rotational position set in the control lever (30), and
    wherein the control lever (30) is configured such that, in the second axial position of the cam follower, only the first valve opening (32a, 32b) is optionally open or closed through rotational adjustment of the two lever arms (33a, 33b), depending on the rotational position set in the control lever (30), whereas the second valve opening (32b) remains open irrespective of the rotational position of the control lever (30).
17. Internal combustion engine having a valve train (1) according to any of the preceding claims.

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