Rocker arm assembly for a valve train of an internal combustion engine

Abstract

Rocker arm arrangement for a valve train of an internal combustion engine, comprising at least one rocker arm (1) pivotably arranged on a rocker arm shaft (3) with a valve-side lever (1a) for actuating at least one gas exchange valve (4, 5) of the internal combustion engine and with two actuating-side levers (1b, 1c) for pivoting actuation, wherein the levers (1a, 1b, 1c) are pivotably mounted relative to each other on the rocker arm shaft (3) and, for switching the rocker arm (1), a first actuating-side lever (1b) can be coupled to the valve-side lever (1a) by means of first coupling means (9) for transmitting a first stroke movement for valve actuation and a second actuating-side lever (1c) can be coupled to the valve-side lever (1a) by means of second coupling means (10) for transmitting a second stroke movement for valve actuation, wherein, in addition to the first rocker arm (1), a second rocker arm (2) is arranged on the rocker arm shaft (3).wherein the second rocker arm (2) is pivotably arranged on the rocker arm axis (3) with a second valve-side lever (2a) for actuating at least one gas exchange valve (6, 7) of the internal combustion engine and a third pivotably actuating-side lever (2b), wherein the levers (2a, 2b) are pivotably mounted relative to each other on the rocker arm axis (3) and, for switching the second rocker arm (2), the third actuating-side lever (2b) can be coupled to the second valve-side lever (2a) by means of third coupling means (11) for transmitting a third stroke movement for valve actuation, characterized in that at least one exhaust gas exchange valve (4, 5) can be actuated independently of each other by the first switchable rocker arm (1) and at least one intake gas exchange valve (6, 7) for a cylinder of the internal combustion engine can be actuated independently of each other by the second switchable rocker arm (2).by the first valve-side lever (1a) being in valve contact with at least one exhaust gas exchange valve (4, 5) of the internal combustion engine and the second valve-side lever (2a) being in valve contact with at least one intake gas exchange valve (6, 7).

Description

The invention relates to a rocker arm arrangement for a valve train of an internal combustion engine according to the type defined in more detail in the preamble of claim 1. From DE 10 2017 129 720 A1, a switchable rocker arm arrangement is known with a rocker arm which is mounted on a machine-fixed rocker arm axis and has a cam arm connected to a camshaft and a valve arm connected to at least one gas exchange valve of a reciprocating internal combustion engine. The valve train system for an engine, known from US 2006 / 0 236 968 A1, is designed with a low-lift rocker arm, a high-lift rocker arm and a connecting rocker arm, wherein the rocker arms can be connected by a low-lift locking mechanism and a high-lift locking mechanism. US patent 2016 / 0230679A1 discloses a variable valve operating system with three rocker arms that can be coupled by means of a switching device. A variable valve train known from JP 2013-142328 A has a main rocker arm and two cam follower rocker arms, which can be connected to each other by means of switching bolts. The invention is therefore based on the objective of proposing a rocker arm arrangement of the aforementioned type, which enables a simple and operationally improved variable valve control. The problem is solved by the features of claim 1. Further advantageous embodiments are described in the respective dependent claims, the description, and the drawings. A rocker arm arrangement for the valve train of an internal combustion engine with at least one rocker arm is proposed. The rocker arm is pivotably mounted on a rocker arm shaft with a valve-side lever for actuating at least one gas exchange valve of the internal combustion engine and with two actuating-side levers for pivoting the rocker arm. The levers are pivotably mounted relative to each other on the rocker arm shaft. For switching the rocker arm, a first actuating-side lever can be coupled to the valve-side lever by means of first coupling means for transmitting a first stroke movement for valve actuation, and a second actuating-side lever can be coupled to the valve-side lever by means of second coupling means for transmitting a second stroke movement for valve actuation. In this way, the valve-side lever can be selectively switched by the actuating-side levers.A simple, multi-variable operation, in particular a combination of valve lift reduction and valve lift switching, with at least one switchable rocker arm, is enabled. Here, the valve lift can be completely switched off, an additional valve lift can be added to a full valve lift, or the latter can be deactivated. A further advantage is that the valve lift height of the additional valve lift is lower than that of the full valve lift and, in particular, can be set directly below it. This makes a so-called Miller lift possible. The rocker arm offers a particularly advantageous way to transmit four different and independent lift curves. The valve-side lever can be decoupled from both actuating-side levers, enabling valve lift cut-off in a basic curve. The valve-side lever can be coupled to a first actuating-side lever while remaining decoupled from a second actuating-side lever. This allows for the transmission of only a full valve lift, for example, one taken from a primary cam, in a second lift curve. The valve-side lever can be coupled to both actuating-side levers simultaneously, allowing for the transmission of a combination of full valve lift and additional valve lift in a third lift curve. This is particularly advantageous in the case of internal exhaust gas recirculation in the internal combustion engine.In a fourth lift curve, the valve-side lever can be coupled to the second actuating-side lever, while it can be decoupled from the first actuating lever. This allows the transmission of only one additional valve lift, for example, one derived from a secondary cam. This would be the case, for instance, for the Miller lift mentioned above on the intake valve side, or for an engine brake and / or for implementing so-called engine thermal management on the exhaust valve side to reduce thermal stress and wear on the components. According to the invention, in addition to the first switchable rocker arm, a second switchable rocker arm is provided. The latter is pivotably arranged on the rocker arm shaft with a second valve-side lever for actuating at least one gas exchange valve of the internal combustion engine and with a third actuating-side lever that can be pivotally driven, the levers being pivotably mounted relative to each other on the rocker arm shaft. To switch the second rocker arm, the third actuating-side lever can be coupled to the second valve-side lever by means of a third coupling device for transmitting a third stroke movement for valve actuation. In this way, the second rocker arm can be switched independently of the first rocker arm and vice versa. It is possible to independently control at least one exhaust gas exchange valve and at least one intake gas exchange valve for a cylinder of the internal combustion engine using the first switchable rocker arm. This is achieved simply by having the first valve-side rocker arm in contact with at least one exhaust gas exchange valve of the internal combustion engine and the second valve-side rocker arm in contact with at least one intake gas exchange valve. In a further particularly advantageous embodiment of the invention, the first actuating-side lever and the third actuating-side lever are each in contact with a first cam of a camshaft of the internal combustion engine for the purpose of tapping off a full valve lift for valve actuation. This allows the transmission of a full valve lift or deactivation, or a combined cylinder deactivation, to occur independently at the first and second rocker arms. Since the second actuating-side lever is in contact with a second cam of the camshaft for tapping off an additional valve lift, the transmission of an additional valve lift alone, without a full valve lift, or the transmission of an additional valve lift together with the transmission of a full valve lift, is possible at the first rocker arm during one camshaft revolution. This arrangement also enables rolling or alternating cylinder deactivation and, at the same time, stepless or variable cylinder deactivation.A selectively and independently implementable engine brake for each cylinder. The actuating levers allow for direct pickup of the stroke movement from the respective cam lobe of the camshaft, thus eliminating the need for additional transmission components. Friction losses during pickup can be minimized by a cam roller. The design can be further simplified if each coupling element is assigned an actuator for switching and each rocker arm can be switched individually by a separate actuator. This allows the actuators to be made smaller and manufactured in larger numbers at lower production costs. It is advantageous if the actuators are designed as electric solenoids, each featuring a linearly displaceable armature through which the respective coupling elements for switching can be moved in direct contact. This eliminates the need for additional components to transmit the actuating movement. The actuator stroke is reduced, and the switching time is shortened. Furthermore, the direct, individual actuation of each rocker arm increases switching performance and simultaneously reduces switching time variance. The influence of component tolerances and manufacturing costs can be minimized. The actuators can be at least partially integrated into a carrier connected to the rocker arm axis and arranged at a radial distance from the rocker arm axis. This allows the actuators to be arranged on the carrier at any desired individual radial distance from the rocker arm axis in a particularly simple manner. This enables the actuators and coupling elements to be positioned close to the rocker arm axis, thus minimizing the relative movement of coupling elements integrated, for example, into the valve-side lever or an actuating-side lever, during operation. Permanent contact between the actuator and the coupling elements for switching is easily established in this way. Furthermore, the rocker arm assembly, comprising the actuators, rocker arm axis, and rocker arms, can be easily attached to the cylinder head of the internal combustion engine as a pre-assembled unit via the carrier, particularly by means of a bolted connection. In a further advantageous embodiment of the invention, the coupling means are integrated into the rocker arms and slidably arranged in corresponding axial bores on the valve-side levers and on the corresponding actuator-side levers for switching. This enables axial coupling of the corresponding valve-side and actuator-side levers transversely to the longitudinal axis of the levers, thus providing a so-called transverse locking of the switchable rocker arms. The transverse locking allows for a space-saving arrangement of the coupling means close to the rocker arm axis. The first and third coupling means can each have an actuating piston that is movable in an axial through-bore on the respective first and third valve-side lever, by means of which a coupling piston arranged in an axial bore on the respective first and third actuating-side lever can be moved for switching purposes in direct actuating contact. The latter is movable into the through-bore of the respective first and third valve-side lever for coupling with it. It is further advantageous if the coupling means integrated into a valve-side lever or an actuating-side lever for switching, and at least one actuator associated with them for switching, are arranged such that, when the respective valve-side lever or actuating-side lever pivots relative to the respective actuator, at least partial overlap in the direction of movement between the coupling means and the actuator for switching is ensured. In this way, the coupling means can be permanently controlled by the actuator for switching. The coupling means can be in permanent contact with the actuator during overlap or be spaced apart by a small air gap. Advantageously, it is also possible to arrange a slidably integrated coupling element and at least the actuator integrated into the carrier, which is associated with the latter for actuation, in such a way that, when the slidably integrated lever pivots relative to the carrier, the coupling element can be applied to the carrier in the direction of movement when decoupled. In this decoupled state, the coupling element can thus be permanently applied to the carrier in a sliding pivot contact. This provides a simple, permanent means of securing the coupling element against falling out of the slidably integrated lever. Coupling elements slidably integrated into a valve-side lever for switching can be secured against falling out in an analogous manner when decoupled. Return springs can be provided that bias at least one actuating lever and at least one associated valve-side lever against each other in the pivoting direction, into an unpivoted home position. For this purpose, axially aligned recesses are provided on the axially opposite longitudinal sides of each actuating lever and each valve-side lever, into which the return springs are at least partially arranged and biased in the pivoting direction. The return springs can thus be integrated into one or both rocker arms in a particularly space-saving manner. In a further particularly advantageous embodiment of the invention, the first and third coupling means for coupling the first and second valve-side levers with the first and third actuating-side levers are each pre-tensioned into the coupled state by spring means. The second coupling means for coupling the first valve-side lever with the second actuating-side lever are pre-tensioned into the decoupled state by spring means. In this simple manner, when the coupling means are not actuated, the first and second valve-side levers are held in a coupled state with the first and third actuating levers, respectively, by the first and third coupling means, while the first valve-side lever is decoupled from the second actuating-side lever. This allows, for example, a full valve stroke to be transmitted by the first and second rocker arms, while the auxiliary valve stroke is deactivated. The first and second rocker arms can be switched and actuated independently of each other. For example, it is possible to actuate at least one exhaust gas exchange valve of the internal combustion engine by means of the first rocker arm and at least one intake gas exchange valve by means of the second rocker arm. Conversely, and outside the scope of the invention, it is also conceivable to actuate at least one intake gas exchange valve by means of the first rocker arm and at least one exhaust gas exchange valve by means of the second rocker arm. Integrating the actuators into a common carrier connected to the shared rocker arm shaft, on which the switchable rocker arms with their valve-side and actuator-side levers are mounted, allows the rocker arm assembly to be designed as a pre-assembled unit that can be easily attached to the cylinder head of the internal combustion engine via the carrier. A screw connection can be provided for attaching the rocker arm shaft to the carrier and for attaching the carrier to the cylinder head. The switchable rocker arm assembly can thus be individually mounted directly to the cylinder head for each cylinder. It is also possible to arrange multiple rocker arms on a common rocker arm shaft for all cylinders. Accordingly, it can then be selected whether only individual cylinders are equipped with the switchable rocker arm unit.For example, to deactivate cylinders, only half of the internal combustion engine's cylinders can be equipped with the rocker arm arrangement. However, it is also conceivable to equip all cylinders accordingly if overrun fuel cut-off or so-called coasting operation of the engine is to be implemented. The invention is explained in more detail with reference to the drawings. Figures 1, 2 to 3 each show a perspective view of a rocker arm arrangement according to the invention in different operating states; Figure 4 shows a view of the rocker arm arrangement in a first switching state, cut in a first sectional plane; Figure 5 shows a view of the rocker arm arrangement in the first switching state, cut in a second sectional plane; Figure 6 shows a view of the rocker arm arrangement in a second switching state, cut in the first sectional plane; Figure 7 shows a view of the rocker arm arrangement in a third switching state, cut in the second sectional plane; Figure 8 shows a view of the rocker arm arrangement, cut in a third sectional plane. The rocker arm arrangement according to the invention, shown in Figures 1, 2 to 3, comprises a first and a second rocker arm 1, 2, which are arranged on a common rocker arm axis 3 that is fixed to a specific location or machine. The first rocker arm 1 consists of a first valve-side lever 1a for actuating two exhaust gas exchange valves 4, 5 of the internal combustion engine and two actuating-side levers 1b, 1c for pivoting the drive mechanism. The second rocker arm 2 comprises a second valve-side lever 2a for actuating two intake gas exchange valves 6, 7 of the internal combustion engine and a third actuating-side lever 2b that can be pivoted. The valve-side and actuating-side levers 1a, 1b, 1c, 2a, 2b are each pivotably arranged relative to each other on the rocker arm axis 3. The pivoting drive of the actuating-side levers 1b, 1c, 2b is effected via an overhead camshaft 8. To switch the first rocker arm 1, the first actuating-side lever 1b can be coupled to the first valve-side lever 1a via first coupling means 9, and the second actuating-side lever 1c can be coupled to the first valve-side lever 1a via second coupling means 10. In this way, the first rocker arm 1 is designed as a switchable triple rocker arm. To switch the second rocker arm 2, the second valve-side lever 2a can be coupled to the third actuating-side lever 2b via third coupling means 11. The coupling means 9, 10, and 11 can each be selectively switched by an associated separate electrical actuator 12, 13, or 14. The actuating levers 1b, 1c, 2b are each pivotally connected at one end to a cam roller 15, 16, 17 in direct contact with an associated cam 18, 19, 20 of the camshaft 8 to detect a cam stroke movement. The valve-side levers 1a, 2a transmit the cam stroke movement detected by the actuating levers 1b, 1c, 2b as a valve stroke movement to the respective gas exchange valves 4, 5 and 6, 7 of the internal combustion engine. For this purpose, the valve-side levers 1a, 2a are in contact at one valve-side lever end with two exhaust gas exchange valves 4, 5 and two intake gas exchange valves 6, 7 of each cylinder of the internal combustion engine. Two gas exchange valves 4, 5 and 6, 7 respectively can be connected via a fork-shaped valve contact 21, 22, a so-called valve bridge, at the valve-side lever end region of the respective axially internal valve-side lever 1a, 2a.Four gas exchange valves per cylinder can be actuated simultaneously. Alternatively, only one gas exchange valve per cylinder can be actuated at a time, i.e., two gas exchange valves per cylinder, in which case a valve bridge is not required. The rocker arm arrangement with two switchable rocker arms 1, 2 shown in Fig. 1 and Fig. 2 serves for variable valve control on an engine (not shown) for a truck, which is depicted with a single overhead camshaft 8 driving the rocker arms 1, 2. The valve-side levers 1a, 2a are each designed as double-sided levers, the pivot points of which are located on the rocker arm axis 3 in a central area between the respective valve-side lever end region with the valve contact 21, 22 and a coupling-side lever end region 23, 24, so that the valve-side lever end regions and the coupling-side lever end regions 23, 24 are pivotable about the rocker arm axis 3. At the coupling-side lever end region 23 or 24, the valve-side levers 1a and 2a can be coupled to the actuating-side levers 1b, 1c, and 2b, respectively, to transmit a valve lift movement. This allows the coupling means 9, 10, 11 and the associated actuators 12, 13, 14 to be arranged on the camshaft side of the rocker arm axis 3 between this axis and the camshaft 8. The actuating levers 1b, 1c, and 2b are arranged parallel to the valve-side levers 1a and 2a, respectively, and each is pivotably mounted with one support end on the common rocker arm axis 3. The first actuating lever 1b flanks the first valve-side lever 1a on its axially outer side facing away from the second rocker arm 2, while the second actuating lever 1c is positioned on its axially inner side facing the second rocker arm 2. The third actuating lever 2b is arranged on the axially outer side of the second valve-side lever 2a facing away from the first rocker arm 1. The actuating levers 1b, 1c, 2b each engage cam rollers 15, 16, 17 to transmit a cam stroke movement for valve actuation from the respective cam 18, 19, 20 of the camshaft 8. The cam rollers 15, 16, 17 are each located at the end of the actuating levers 1b, 1c, 2b furthest from the support end. The first actuating lever 1b engages cam roller 15 to transmit a first stroke movement, the full valve lift, from the first cam 18 (primary cam), while the second actuating lever 1c engages cam roller 16 to transmit a second stroke movement, the additional valve lift, from a second cam 19 (secondary cam). The third actuation-side lever 2b allows a third stroke movement, as a full valve lift, to be taken from the third cam 20 of the camshaft 8 via the cam roller 17. In this way, a full valve lift and / or an additional valve lift can be transmitted to the exhaust gas exchange valves 4, 5 via the first valve-side lever 1a.The second valve-side lever 2a allows a full valve lift to be transferred to the inlet gas exchange valves 6, 7. In Fig. 1, the rocker arm assembly is shown in a first operating state during the base circle phase of the cams 18, 19, 20, while in Fig. 2, in a second operating state, the exhaust primary cam 18 is in the cam lift phase, and the exhaust secondary cam 19 and the intake cam 20 are each in the base circle phase. In a third operating state according to Fig. 3, the intake cam 20 is in the cam lift phase. The exhaust primary cam 18 and the exhaust secondary cam 19 are in the base circle phase. During the cam lift phase, the respective actuating-side lever 1b, 1c, 2b is actuated by tapping a cam lift, while it is unactuated during the base circle phase. The coupling elements 9, 10, 11 are each integrated into the associated valve-side levers 1a, 2a and actuating-side levers 1b, 1c, 2b in a space-saving manner. Figures 4 and 6 show the rocker arm arrangement in a section with a first section plane passing through the first and third coupling elements 9, 11 and through the associated actuators 12, 14. The first and third coupling elements 9, 11 each have a cylindrical actuating piston 9a, 11a and a cylindrical coupling piston 9b, 11b. The actuating pistons 9a, 11a are each slidably arranged in an axial through-bore 25 or 26 at the coupling-side lever end region 23 or 24 of the first or second valve-side lever 1a, 2a for switching purposes. On the first and third actuating-side levers 1b and 2b respectively, the respective coupling piston 9b and 11b are slidably mounted in an axial bore 27 and 28 respectively. The actuating pistons 9a and 11a are each axially displaceable at one actuator-side end in direct contact with the respective actuator 12, 14. At their other end, they are in contact with the respective coupling pistons 9b, 11b. The latter are biased against the respective actuating pistons 9a, 11a by springs 29, 30. The springs 29, 30 are each arranged coaxially as helical compression springs in the bores 27, 28. The movement of the actuating pistons 9a, 11a is limited by a bushing 31, 32 pressed into the through bores 25, 26 at the actuator-side end and by an axial stop 31a, 32a formed on the end face of each bushing. Figures 5 and 7 show the rocker arm assembly in a section view with a second sectional plane passing through the second coupling means 10 and the associated actuator 13. The second coupling means 10 are formed by a cylindrical coupling piston 10a, which is slidably arranged in an axial through-bore 33 of the second actuating-side lever 1c for switching. The coupling piston 10a is axially displaceable at one actuator-side end face in direct actuating contact with the actuator 13. For coupling, it is displaceable into an axial bore 34 on the first valve-side lever 1a. The bore 34 is designed here as an axial through-bore. The coupling piston 10a is biased against the actuator 13 by spring means 35. The spring means 35 are arranged coaxially in the bore 34 as helical compression springs. For coupling, the coupling pistons 9b, 10a, 11b are each, as shown in Fig. 4 and Fig. 7, movable in their unpivoted basic position from the respective valve-side and actuating-side levers 1a and 1b, 1a and 1c, or 2a and 2b in the respective basic circle phase of the cams 18, 19, 20 (Fig. 1) with a coupling-side end out of the coupling-side end of the bore 27, 28 on the respective valve-side lever 1a or 2a or the through bore 33 on the second actuating-side lever 1c into the respective through bore 25, 26 on the respective actuating-side lever 1b, 2b or into the bore 34 of the first valve-side lever 1a. The coupling pistons 9b, 10a, 11b can be moved into the coupled position by the spring force of the respective pre-tensioned spring elements 29, 30 or against the spring force of the spring elements 35. At the same time, the spring elements 35 are pre-tensioned for decoupling. The decoupling according to Fig. 5 and Fig. 1.6 is effected by actuating the respective actuator 12, 14 and displacing the respective actuating piston 9a, 11a into contact with the respective coupling pistons 9b, 11b against the spring force of the respective spring elements 29, 30 or by the spring force of the pre-tensioned spring elements 35. In doing so, the coupling pistons 9b, 10a, 11b are pushed back into the respective bore 27, 28 or into the through bore 33, and at the same time the spring elements 29, 30 are pre-tensioned for coupling. The actuators 12, 13, 14 are each designed as electric lifting or linear magnets (Fig. 1, Fig. 2 to Fig. 3). They are mounted in a common support 36 arranged axially between the rocker arms 1, 2, which is connected to the rocker arm axis 3 via a first screw connection 37 to a base plate 36a. The support 36 has two arms 36b 36c extending from the base plate 36a perpendicular to the rocker arm axis 3, which are arranged parallel to the rocker arms 1, 2 and extend in the direction of the camshaft 8, which is arranged parallel to the rocker arm axis 3. The arms 36b, 36c form cylindrical bushings 38, 39, 40, in which the actuators 12, 13, 14 are each arranged with an electromagnetically linearly displaceable armature 12a, 13a, 14a (Fig. 4, Fig. 5, Fig. 6 to Fig. 7).On arms 36b, 36c the actuators 12, 13, 14 can each be arranged in the bushings 38, 39, 40 at any radial distance to the rocker arm axis 3 and at the same time on the camshaft side of the rocker arm axis 3 between this and the camshaft 8. By energizing the lifting magnets, the respective armature 12a, 13a, 14a, with one coupling end in direct actuating contact with the respective coupling means 9, 10, 11, can be moved out of the respective socket 38, 39, 40 for switching. By switching off the energization, the actuators 12, 13, 14 can be deactivated and the respective armature 12a, 13a, 14a can be moved back into the respective socket 38, 39, 40. To return the armatures 12a, 13a, 14a to their original position when de-energized, return spring means 12b, 13b, 14b can be arranged in the respective lifting magnets as shown. The carrier 36 forms a first and a second bushing 38, 39 on a first arm 36b. The arm 36b with the bushings 38, 39 is arranged on the axial inner side of the second actuating-side lever 1c, facing away from the first valve-side lever 1a. The bushings 38, 39 are located opposite the axial inner side of the second actuating-side lever 1c.The first and second actuators 12 and 13, respectively, are arranged in bushings 38 and 39 with their respective armatures 12a and 13a for direct actuating contact with the respective actuating piston 9a and coupling piston 10a of the first and second coupling means 9 and 10, respectively. The second arm 36c is formed with a third bushing 40 and is guided along the axial inner side of the second valve-side lever 2a. The bushing 40 is located opposite the axial inner side of the second valve-side lever 2a. The third actuator 14, with its armature 14a, is arranged in the third bushing 40 on the second arm 36c for direct actuating contact with the actuating piston 11a of the third coupling means 11. In a first switching state of the rocker arm assembly, shown in Figs. 4 and 5, the actuators 12, 13, 14 are in the deactivated state, i.e., all three solenoids are not energized and the armatures 12a, 13a, 14a are retracted into their respective bushings 38, 39, 40. The first valve-side lever 1a is coupled to the first actuating-side lever 1b by the first coupling means 9 (Fig. 4) and simultaneously decoupled from the second actuating-side lever 1c by the second coupling means 10 (Fig. 5). The latter is therefore in its idle stroke, since the additional valve stroke taken from the second cam 19 is without any travel (Fig. 2). In this process, only the full valve lift taken from the first actuating-side lever 1b on the first cam 18 is transferred via the first valve-side lever 1a to the exhaust gas exchange valves 4, 5.Simultaneously, the second valve-side lever 2a is coupled to the third actuating-side lever 2b by the third coupling means 11 (Fig. 4). This allows the inlet gas exchange valves 6, 7 to be actuated via the second valve-side lever 2a with the full valve lift taken from the third cam 20 by the first actuating-side lever 1b (Fig. 2). The deactivated actuators 12, 14, with their armatures 12a, 14a retracted into the bushings 38, 40, are each in at least partial axial overlap with the end faces of the actuator-side ends of the first and third actuating pistons 9a, 11a, respectively, which are pivoted by the first and second valve-side levers 1a, 2a, respectively (Fig. 4 and Fig. 6). This means that the first and second coupling means 9, 11 can be permanently controlled without delay by the first and third actuators 12, 14.This is also made possible by the fact that the actuators 12, 14 in the carrier 16 and the coupling means 9, 11 in the valve-side levers 1a, 2a are arranged close to the rocker arm axis 3 and therefore the absolute movement of the actuating pistons 9a, 11a during a pivoting movement of the valve-side levers 1a, 2a is small, even with a full valve lift. Since the second actuator 13 is deactivated in the first switching state according to Fig. 5, the second coupling piston 10a is moved into the decoupled position by the spring force of the associated spring means 35. Its mushroom-shaped, actuator-side end 41 rests axially against the end face of the first arm 36b of the support 36. With this mushroom-shaped end 41, the second coupling piston 10a slides back and forth along the end face of the first arm 36b during a pivoting movement of the second actuating-side lever 1c. In this way, it is secured against falling out of the through-hole 33 in the support 36. In the second switching state of the rocker arm assembly shown in Fig. 6, only the first and third actuators 12, 14 are activated. The extended armatures 12a, 14a move the first and third coupling elements 9, 11 into the decoupled position, decoupling the first valve-side lever 1a from the first actuating-side lever 1b and the third valve-side lever 2a from the third actuating-side lever 2b. Since the second actuator 13 is deactivated, the second actuating-side lever 1c is decoupled from the first valve-side lever 1a. This deactivates the first valve-side lever 1a and the second valve-side lever 2a. The decoupled first and third actuating-side levers 1b, 2b are in their idle stroke, as the full valve stroke tapped by them at the first and second cams 18, 19, respectively, is lost (Fig. 2).This deactivates both rocker arms 1, 2, preventing them from transmitting any valve lift to the gas exchange valves 4, 5 and 6, 7 respectively (Fig. 2). In this way, cylinder deactivation is achieved in the second operating state of the rocker arm arrangement. According to Fig. 7, in a third switching state of the rocker arm arrangement, the second actuator 13 is activated, while the first actuator 12 is deactivated. The armature 13a of the second actuator 13 is extended. In this state, the first valve-side lever 1a is coupled to the second actuating-side lever 1c via the second coupling means 10, and the additional valve stroke taken from the latter at the second cam 19 is transferred to the former (Fig. 3). Since the first valve-side lever 1a is simultaneously coupled to the first actuating-side lever 1b via the first coupling means 9 (Fig. 4), the full valve stroke taken from the latter at the first cam 18 is also transferred to the former (Fig. 3). In this process, the exhaust gas exchange valves 4, 5 are actuated by the first valve-side lever 1a with the full valve lift of the primary cam 18 and by the switchable additional valve lift of the secondary cam 19. In a fourth switching state of the rocker arm arrangement, the first actuator 12 can be activated and the first valve-side lever 1a can be decoupled from the first actuating-side lever 1b by the first coupling means 9. The latter thus enters its idle stroke. In this way, only the additional valve stroke tapped off by the second actuating-side lever 1c at the secondary cam 19 is transmitted by the first valve-side lever 1a to the exhaust gas exchange valves 4, 5 (Fig. 3). The actuators 12, 13, 14 with the anchors 12a, 13a, 14a and the coupling means 9, 10, 11 in the bores 27, 28, 34 and the through bores 25, 26, 33 are each arranged parallel to the rocker arm axis 3 and transversely to the longitudinal axis of the rocker arms 1, 2 for switching. In this way, the rocker arms 1, 2 can be switched by a space-saving so-called transverse locking mechanism, which at the same time allows the coupling means 9, 10, 11 to be arranged close to the rocker arm axis. The rocker arms 1 and 2 can each be actuated individually by actuators 12, 13, and 14, respectively. The solenoids of actuators 12, 13, and 14 are controlled by electronic control units (not shown). For this purpose, a central contact, in particular a central connector, is integrated into the rocker arm assembly. A connection to the engine control unit (not shown) can be located outside the cylinder head of the internal combustion engine. The solenoids can be activated by a switching command from the engine control unit, a so-called CAN signal. The integrated electronics calculate the exact energizing time of the solenoids. Furthermore, the integrated electronics also determine which of the individual solenoids is activated. The rocker arm assembly can be easily attached to the indicated cylinder head 43 of the internal combustion engine by means of a second screw connection 42, as shown in Fig. 8. For this purpose, several screws of the screw connection 42 are passed through radial through-holes 44, 45 in the rocker arm shaft 3 in the area of ​​the base plate 36a of the support 36 and screwed into a threaded hole 46, 47 in the cylinder head 43 (Figs. 1 to 3 and 8). It is also conceivable to attach the rocker arm shaft 3 and the support 36 to the cylinder head 43 by means of the first or the second screw connection 37, 42 (Figs. 1, 2 to 3). According to Figures 4, 5, 6, 7 to 8, return springs 48, 49, 50 are provided, each of which biases the respective valve-side lever 1a, 2a and the respective associated actuating-side lever 1b, 1c, 2b against each other into the unpivoted home position. The return springs 48, 49, 50 serve to return the levers to their home position in a decoupled state. The first and second return springs 48, 49 are each arranged between the first valve-side lever 1a and the first and second actuating-side levers 1b, 1c, respectively, and the third return spring 50 is arranged acting between the second valve-side lever 2a and the third actuating-side lever 2b. The return spring elements 48, 49, 50 are each designed as a torsion spring, preferably as a torsion leg spring. They are arranged coaxially to the rocker arm axis 3 in a coil-like shape in axially aligned, axially opposite annular recesses 51, 52 or 53, 54 or 55, 56 on the respective opposite axial longitudinal sides of the respective valve-side levers 1a, 2a and the respective actuating-side levers 1b, 1c, 2b associated with them. Each spring end is pre-tensioned in the pivoting direction at the respective valve-side lever 1a, 2a and at the other spring end at the respective actuating-side lever 1b, 1c, 2b.First return spring elements 48 are accommodated in a first recess 51 on the outer axial longitudinal side of the lever arm of the first valve-side lever 1a, facing away from the second actuating-side lever 1c, and in a second recess 52 on the inner axial longitudinal side of the lever arm of the first actuating-side lever 1b, which is aligned opposite this recess. Second return spring elements 49 are accommodated in a third recess 53 formed on the inner axial longitudinal side of the lever arm of the first valve-side lever 1a, facing away from the first actuating-side lever 1b, and in a fourth recess 54 corresponding to this third recess 53 on the outer axial longitudinal side of the lever arm of the second actuating-side lever 1c.To accommodate a third return spring element 50, a fifth recess 55 is provided on the outer axial longitudinal side of the lever 2a on the second valve side, which corresponds to a sixth recess 56 on the outer axial longitudinal side of the lever 2b on the third actuating side. The return spring elements 48, 49, 50 are guided radially and axially in the recesses 51, 52, 53, 54, and 55, 56, respectively. Reference symbol list 1 Rocker arm 1a Lever 1b Lever 1c Lever 2 Rocker arm 2a Lever 2b Lever 3 Rocker arm shaft 4 Gas exchange valve 5 Gas exchange valve 6 Gas exchange valve 7 Gas exchange valve 8 Camshaft 9 Coupling means 9a Actuating piston 9b Coupling piston 10 Coupling means 10a Coupling piston 11 Coupling means 11a Actuating piston 11b Coupling piston 12 Actuator 12a Armature 12b Return spring means 13 Actuator 13a Armature 13b Return spring means 14 Actuator 14a Armature 14b Return spring means 15 Cam roller 16 Cam roller 17 Cam roller 18 Cam, primary cam 19 Cam,Secondary cam 20 Cam 21 Valve contact 22 Valve contact 23 Lever end area 24 Lever end area 25 Through hole 26 Through hole 27 Hole 28 Hole 29 Spring center 30 Spring center 31 Bushing 31a Stop 32 Bushing 32a Stop 33 Through hole 34 Hole 35 Spring center 36 Carrier 36a Base plate 36b Arm 36c Arm 37 Screw connection 38 Bushing 39 Bushing 40 Bushing 41 End 42 Screw connection 43 Cylinder head 44 Through hole 45 Through hole 46 Threaded hole 47 Threaded hole 48 Return spring center 49 Return spring center 50 Return spring center 51 Recess 52 Recess 53 Recess 54 Recess 55 Recess 56 Recess

Claims

Rocker arm arrangement for a valve train of an internal combustion engine, comprising at least one rocker arm (1) pivotably arranged on a rocker arm shaft (3) with a valve-side lever (1a) for actuating at least one gas exchange valve (4, 5) of the internal combustion engine and with two actuating-side levers (1b, 1c) for pivoting actuation, wherein the levers (1a, 1b, 1c) are pivotably mounted relative to each other on the rocker arm shaft (3) and, for switching the rocker arm (1), a first actuating-side lever (1b) can be coupled to the valve-side lever (1a) by means of first coupling means (9) for transmitting a first stroke movement for valve actuation and a second actuating-side lever (1c) can be coupled to the valve-side lever (1a) by means of second coupling means (10) for transmitting a second stroke movement for valve actuation, wherein, in addition to the first rocker arm (1), a second rocker arm (2) is arranged on the rocker arm shaft (3).wherein the second rocker arm (2) is pivotably arranged on the rocker arm axis (3) with a second valve-side lever (2a) for actuating at least one gas exchange valve (6, 7) of the internal combustion engine and a third pivotably actuating-side lever (2b), wherein the levers (2a, 2b) are pivotably mounted relative to each other on the rocker arm axis (3) and, for switching the second rocker arm (2), the third actuating-side lever (2b) can be coupled to the second valve-side lever (2a) by means of third coupling means (11) for transmitting a third stroke movement for valve actuation, characterized in that at least one exhaust gas exchange valve (4, 5) and at least one intake gas exchange valve (6, 7) for a cylinder of the internal combustion engine can be actuated independently of each other by the first switchable rocker arm (1) and by the second switchable rocker arm (2) can be actuated independently of each other.by the first valve-side lever (1a) being in valve contact with at least one exhaust gas exchange valve (4, 5) of the internal combustion engine and the second valve-side lever (2a) being in valve contact with at least one intake gas exchange valve (6, 7). Rocker arm arrangement according to claim 1, characterized in that the first actuating-side lever (1b) for tapping a full valve lift for valve actuation is in contact with a first cam (18) of a camshaft (8) of the internal combustion engine, and the second actuating-side lever (1c) for tapping an additional valve lift for valve actuation is in contact with a second cam (19) of the camshaft (8), and the third actuating-side lever (2b) for tapping a full valve lift for valve actuation is in contact with a third cam (20) of the camshaft (8). Toggle lever arrangement according to one of claims 1 or 2, characterized in that each coupling means (9, 10, 11) is assigned an actuator (12, 13, 14) for switching, wherein the actuators (12, 13, 14) are designed as electric lifting magnets, each having a linearly displaceable armature (12a, 13a, 14a) by which the respective coupling means (9, 10, 11) can be displaced for switching in direct actuating contact. Rocker arm arrangement according to claim 3, characterized in that the actuators (12, 13, 14) are at least partially integrated into a carrier (36) connected to the rocker arm axis (3) and are arranged at a radial distance to the rocker arm axis (3). rocker arm arrangement according to one of claims 1 to 4, characterized in that the coupling means (9, 10, 11) are arranged axially displaceable in respective associated axial bores (25, 27 and 26, 28 or 33, 34) on the valve-side levers (1a, 2a) and on the respective associated actuating-side levers (1b, 1c, 2b) for switching. A rocker arm arrangement according to one of claims 3 or 4 or according to claim 5, insofar as it refers back to claim 3 or 4, characterized in that coupling means (9, 10, 11) are integrated slidably into at least one of the valve-side levers (1a, 2a) or into one of the actuating-side levers (1c) for switching and at least one actuator (12, 13, 14) associated therewith for switching are arranged such that, in the event of a relative pivoting of the respective valve-side lever (1a, 2a) or actuating-side lever (1c) relative to the respective actuator (12, 13, 14), at least partial overlap in the direction of movement between the coupling means (9, 10, 11) and the actuator (12, 13, 14) for switching is ensured. A rocker arm arrangement according to one of claims 1 to 6, characterized in that at least in one of the actuating-side levers (1c) for switching, the slidably integrated coupling means (10) and at least the actuator (13) integrated into a carrier (36) for actuation are arranged such that, in the event of a relative pivoting of the actuating-side lever (1c) relative to the carrier (36), the coupling means (10) can be applied to the carrier (36) in the direction of displacement in a decoupled state on the actuator side. A rocker arm arrangement according to one of claims 1 to 7, characterized in that return spring means (48, 49, 50) are provided which each bias at least one of the actuating-side levers (1b, 1c, 2b) and the respective valve-side lever (1a, 2a) in the pivoting direction against each other into an unpivoted basic position, wherein axially aligned recesses (51, 52, 53, 54, 55, 56) are provided on the respective axially opposite longitudinal sides of the levers on the respective actuating-side levers (1b, 1c, 2b) and on the respective valve-side levers (1a, 2a), in which the return spring means (48, 49, 50) are each at least partially arranged and each biased in the pivoting direction.

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