Valve train for an internal combustion engine, in particular of a motor vehicle

Abstract

Valve train (10) for an internal combustion engine, comprising a first gas exchange valve (18), a second gas exchange valve (20), a first rocker arm (32) and a common valve bridge (42) for the gas exchange valves (18, 20), via which the gas exchange valves (18, 20) can be actuated by means of the first rocker arm (32) and thereby moved translationally in a first direction of movement (22), wherein the valve bridge (42) comprises: - a bridge actuation area (44) via which the valve bridge (42) can be actuated by means of the first rocker arm (32) and thereby moved translationally parallel to the first direction of movement (22), - a first valve actuation area (46) via which the first gas exchange valve (18) can be actuated by means of the valve bridge (42) by actuating the valve bridge (42), - a second valve actuation area (48) via which the second gas exchange valve (20) can be actuated by means of the valve bridge (42) by actuating the valve bridge (42), wherein the first valve actuation area (46) has a through-opening (56) which is continuous along the first actuation direction (22), - has a first length section (L1) in which the passage opening (56) is completely closed along its circumferential direction (58), and - has a second length section (L2) directly adjoining the first length section (L1) in the first actuation direction (22), in which the through-hole (56) is open at a first location (S1) along its circumferential direction (58) in a first opening direction (60) perpendicular to the actuation direction (22), wherein the second valve actuation area (48) has a groove (63) which is open at a second location (S2) in a second opening direction (64) perpendicular to the first actuation direction (22) and opposite to the first opening direction, wherein the groove (63) is completely closed in a second actuation direction (28) opposite to the first actuation direction (22), characterized in that a valve cap (68) is provided which is formed separately from the gas exchange valves (18, 20), from the rocker arm (32) and from the valve bridge (42),via which the first gas exchange valve (18) can be actuated by means of a second rocker arm (70) of the valve train (10), wherein: , - the valve bridge (42) and the valve cap (68) form a self-contained assembly (74) that can be mounted as a whole, in which the valve cap (68) is held on the valve bridge (42) independently of the gas exchange valves (18, 20) and independently of the rocker arms (32, 70); and / or - the open area (S1) in a second actuation direction (28) opposite to the first actuation direction (22) is covered by a collar (62) of the valve bridge (42) arranged in the first length region (L1), wherein the collar (62) has an extension (X1) extending along the first actuation direction (22), and wherein the valve bridge (42) is displaceable in the second direction of movement (28) opposite to the first actuation direction (22) relative to the gas exchange valves (18, 20), the valve cap (68) and the rocker arms (32, 70) into a disassembly position (D) in which, in the unactuated state, the rocker arms (32, 70) and the gas exchange valves (18, 20) are: ◯ the second gas exchange valve (20) is arranged completely outside the second valve actuation range (48), and ◯ a distance (X2) running along the first direction of actuation (22) between the second rocker arm (70) and the valve cap (68) remaining on the first gas exchange valve (18) when the valve bridge (42) is moved is greater than the extent (X1) of the collar (62).

Description

[0001] The invention relates to a valve train for an internal combustion engine, in particular of a motor vehicle, according to the preamble of claim 1. The invention also relates to an internal combustion engine.

[0002] US Patent 2018 / 0 058 271 A1 discloses a system for actuating at least one of two or more engine valves in an internal combustion engine. The system includes a rocker arm for actuating the two or more engine valves. The system also includes a valve manifold that works in conjunction with the rocker arm to transmit movement from the rocker arm to the two or more engine valves. US Patent 2020 / 0 208 543 A1 discloses a valve manifold for an engine. German Patent AT 518 933 B1 discloses an internal combustion engine with a valve actuating device. German Patent DE 10 2009 048 143 A1 discloses an internal combustion engine with an engine braking device.

[0003] The object of the present invention is to create a valve train for an internal combustion engine so that particularly simple maintenance and / or repair of the internal combustion engine can be achieved.

[0004] This problem is solved by a valve train with the features of claim 1. Advantageous embodiments with expedient further developments of the invention are specified in the remaining claims.

[0005] A first aspect, not belonging to the invention, is disclosed, which relates to a valve bridge for a valve train of an internal combustion engine, preferably designed as a reciprocating piston engine, in particular of a motor vehicle. This means that the motor vehicle, preferably designed as a car, especially a commercial vehicle, in its fully manufactured state, comprises the internal combustion engine and can be driven by means of the internal combustion engine. The internal combustion engine, in its fully manufactured state, comprises the valve train, which in turn comprises the valve bridge. The valve bridge has a bridge actuation area through which the valve bridge can be actuated by means of a first rocker arm of the valve train and is thereby translationally movable in a first actuation direction. The bridge actuation area is thus designed to interact with the first rocker arm.The first rocker arm, for example, is pivotably mounted on a rocker arm shaft and can therefore pivot about a pivot axis relative to the rocker arm shaft. For example, the first rocker arm can be actuated by a cam on a camshaft and thus pivot about the pivot axis relative to the rocker arm shaft. By pivoting the first rocker arm about the pivot axis relative to the rocker arm shaft, the valve bridge can be actuated via the bridge actuation area by means of the first rocker arm. The bridge actuation area is thus designed, for example, to convert a movement, in particular the pivoting, of the first rocker arm into a movement of the valve bridge in the actuation direction relative to the rocker arm shaft.In other words, the bridge actuation area is designed, for example, to transmit a movement, in particular the pivoting, of the first rocker arm to the valve bridge, whereby the valve bridge can be moved translationally relative to the rocker arm axis in the first actuation direction.

[0006] The valve bridge also has a first valve actuation area, through which a first gas exchange valve of the internal combustion engine can be actuated by means of the valve bridge. The valve bridge also has a second valve actuation area, which is spaced apart from the first valve actuation area, for example, particularly in the longitudinal direction of the valve bridge. A second gas exchange valve of the internal combustion engine, provided in addition to the first gas exchange valve, can be actuated by means of the second valve actuation area. Actuating the respective gas exchange valve can be understood, in particular, as moving the gas exchange valve from a closed position to an open position, especially relative to the rocker arm axis and / or translationally.For example, the respective gas exchange valve can be moved from the closed position to the open position in a direction of movement parallel to the first actuation direction. In particular, the respective gas exchange valve can be an exhaust valve. Furthermore, it is preferably provided that the bridge actuation area is spaced apart from the respective valve actuation area. Thus, the valve actuation areas and the bridge actuation area are preferably spaced apart from each other and, in particular, different from each other within the valve bridge, with the bridge actuation area being arranged between the valve actuation areas.

[0007] To enable a particularly simple and therefore time- and cost-effective evaluation and / or repair of the internal combustion engine, the first aspect provides that at least one of the valve actuation areas has a through-opening which is continuous along the actuation direction and, in particular, preferably unlimited in itself, i.e., considered on its own. The through-opening has a first longitudinal region in which it is completely closed along its circumferential direction, which extends around the first actuation direction. This means, in particular, that the through-opening in this first longitudinal region is completely and thus uninterruptedly bounded by a wall of the valve bridge along its circumferential direction.Thus, for example, the passage opening in the first length range is closed or limited in a plane perpendicular to the first direction of actuation and / or in any direction perpendicular to the direction of actuation, and is therefore not open.

[0008] The through-opening also has a second length section that directly adjoins the first length section in the direction of actuation. The feature that the second length section directly adjoins the first length section in the first actuation means that no further length section of the through-opening is arranged between the length sections along the first direction of actuation; rather, the second length section follows directly after the first length section. In the second length section, the through-opening is open along its circumferential direction around the direction of actuation at, in particular, at least or exactly, a first point in a direction perpendicular to the direction of actuation, which is also referred to as the first opening direction.

[0009] It was found that the use of the valve bridge, and in particular the use of its two length ranges, allows for particularly advantageous maintenance and / or repair of the internal combustion engine, also referred to as servicing. This is because, for example, the valve bridge does not need to be completely disassembled to access a mounting point, especially a screw, located below the valve bridge. Specifically, the use of the valve bridge avoids the need to completely disassemble the valve train to access the injector mounting point. Furthermore, the valve bridge can be disassembled in a particularly simple and therefore time- and cost-effective manner to access the injector mounting point, without requiring excessive disassembly of the rest of the valve train.

[0010] Each gas exchange valve is assigned to a gas port of the cylinder head of the internal combustion engine, which may be configured as an exhaust or intake port. In its closed position, the gas exchange valve closes its assigned gas port. In its open position, the gas exchange valve releases its assigned gas port. All gas ports are assigned to the same cylinder of the internal combustion engine. Thus, in the open position of each gas exchange valve, a gas, including at least air, can flow into the cylinder via its assigned gas port (intake port), and / or a gas initially drawn into the cylinder can flow out of the cylinder via its assigned gas port (exhaust port).The aforementioned injector is designed to introduce, for example, liquid fuel into the cylinder, specifically by injecting it directly into the cylinder. The injector is attached to the cylinder head, for example, by means of the aforementioned mounting. In the fully assembled state of the internal combustion engine, the mounting is overlapped or covered by the fully assembled valve manifold in such a way that it is inaccessible to anyone wishing to service or repair the engine. With conventional internal combustion engines, the valve train, or at least the valve manifold, must be disassembled—that is, completely removed—a time-consuming and costly process to access the mounting. Only then can the injector be detached from the cylinder head for servicing, repair, or replacement.

[0011] Such a complete disassembly of the valve bridge or valve train can now be avoided by using the valve bridge, while still providing sufficient access to the fastening in a particularly simple and cost-effective manner.

[0012] On the other hand, a particularly high and, compared to conventional solutions, significantly greater stiffness of the valve bridge, especially of at least one valve actuation area, can be created, since the through-opening or the at least one valve actuation area is not fork-shaped and thus is not open over its entire extent along the actuation direction in the first opening direction, but rather the through-opening or the at least one valve actuation area is completely closed around the circumference in the first length region.In comparison to a fork-shaped design of at least one valve actuation area, a partially annular collar, resembling a bracket, is created in the first longitudinal section. This design results in significantly higher strength and rigidity of the valve bridge, particularly in the first valve actuation area, compared to a fork-shaped design. Simultaneously, the valve bridge can be partially or completely removed, thus providing particularly easy access to the mounting without having to disassemble the entire valve train. Specifically, removal of the rocker arm shaft and the first rocker arm can be avoided, ensuring sufficient access to the injector mounting, which may be a screw connection, for example.As a result, the internal combustion engine can be serviced or repaired particularly quickly and cost-effectively. Furthermore, the likelihood of errors or damage occurring during the removal and installation of components during servicing or repair can be significantly reduced. Additionally, the valve manifold can be designed to allow for advantageous pre-assembly with a valve cap, if present. Thus, the valve cap and valve manifold can form a single, integrated unit, independent of the rest of the valve train, enabling quick and cost-effective assembly as a whole. Consequently, the internal combustion engine can be assembled or manufactured quickly and cost-effectively.

[0013] To enable particularly simple maintenance and / or repair of the internal combustion engine, the first aspect provides that the second valve actuation area has a groove which, along its circumferential direction around the actuation direction, opens at, in particular at least or exactly, a second point in a direction perpendicular to the actuation direction, and which may also be referred to as the second opening direction. The second opening direction is opposite to the first opening direction.

[0014] It is also intended that the groove is completely closed in a second actuation direction opposite to the first. This allows for particularly easy maintenance or repair of the internal combustion engine, as the valve manifold can be easily disassembled to provide sufficient access to the mounting. Furthermore, it ensures a particularly high rigidity of the valve manifold.

[0015] In order to make the valve bridge particularly easy to assemble and disassemble, one embodiment of the first aspect provides for the valve bridge to be made in one piece.

[0016] A second aspect of the invention, relating to a valve train for an internal combustion engine, is also disclosed. The valve train comprises a first gas exchange valve and a second gas exchange valve, which is arranged in addition to the first gas exchange valve and preferably spaced apart from it. The valve train also includes a first rocker arm and a valve bridge common to the gas exchange valves, particularly as described in the first aspect. The gas exchange valves can be actuated via the valve bridge by means of the first rocker arm and are thereby movable translationally in a first direction of movement from the closed position to the open position, particularly relative to a rocker arm axis on which the first rocker arm can be pivotably mounted about a pivot axis relative to the rocker arm axis.The valve bridge is thus designed to transmit a movement, in particular a pivoting, of the first rocker arm to the gas exchange valves, so that the gas exchange valves can be actuated by means of the first rocker arm via the valve bridge by pivoting the first rocker arm about the pivot axis relative to the rocker arm axis.

[0017] The valve bridge has a bridge actuation range through which it can be actuated by means of the first rocker arm and thus moved translationally in an actuation direction parallel to the first direction of movement. The valve bridge also has a first valve actuation range through which the first gas exchange valve can be actuated by the valve bridge. Furthermore, the valve bridge has a second valve actuation range through which the second gas exchange valve can be actuated by the valve bridge.

[0018] To enable particularly simple maintenance and / or repair of the internal combustion engine, the second aspect provides that at least one of the valve actuation areas has a through-opening that is continuous along the first actuation direction. The through-opening also has a first longitudinal section in which it is completely closed along its circumferential direction around the first actuation direction. Furthermore, the through-opening has a second longitudinal section directly adjoining the first longitudinal section in the first actuation direction, in which the through-opening is open along its circumferential direction at, in particular at least or exactly, a first point in a direction perpendicular to the actuation direction.Advantages and beneficial features of the first aspect are to be regarded as advantages and beneficial features of the second aspect, and vice versa.

[0019] The second valve actuation area has a groove which, at one point, opens in a second direction perpendicular to and opposite to the first actuation direction. In the second aspect, the valve train has a valve cap that is separate from the gas exchange valves, the first rocker arm, and the valve bridge. Only the first gas exchange valve can be actuated by means of a second rocker arm. Preferably, the valve train includes a second rocker arm in addition to the first. The second rocker arm is pivotably mounted on the rocker arm axis and can pivot about the pivot axis relative to the rocker arm axis. In particular, both rocker arms can pivot about the pivot axis relative to each other and relative to the rocker arm axis.In particular, it is provided that the first gas exchange valve can be actuated via the valve cap by means of the second rocker arm, while the second rocker arm does not actuate the valve bridge and / or the second gas exchange valve. The second rocker arm is thus, for example, a so-called brake rocker arm, by means of which the second gas exchange valve, preferably designed as an exhaust valve, can be actuated without actuating the first gas exchange valve, thereby enabling engine braking and thus an engine brake of the internal combustion engine, preferably designed as a decompression brake.

[0020] A first embodiment of the invention is characterized in that the valve bridge and the valve cap form a self-contained assembly that can be mounted as a whole, particularly during the initial assembly of the internal combustion engine. In this assembly, the valve cap is held on the valve bridge independently of the gas exchange valves and the two rocker arms. This allows for pre-assembly of the valve bridge and the valve cap into the assembly, thus preventing, for example, the valve cap from being forgotten during the initial assembly of the internal combustion engine. This increases process reliability in a particularly simple, time-saving, and cost-effective manner.

[0021] To achieve sufficient accessibility to the injector mounting in a particularly simple manner, without having to excessively or completely disassemble the valve train, a second embodiment of the invention, provided as an alternative or additional to the first embodiment, provides that the open first point in a second actuation direction opposite to the first actuation device is covered or overlapped by a collar of the valve bridge arranged in the first longitudinal region. As described above, the collar is at least partially annular in the form of a bracket, so that the through-opening in the first longitudinal region is completely closed in the circumferential direction of the through-opening. Thus, the collar extends along the first actuation direction.Furthermore, the valve manifold is displaceable in the opposite direction to the actuating device, relative to the gas exchange valves, the valve cap, and the two rocker arms, into a disassembly position. In the disassembly position, when the first rocker arm and the second rocker arm (brake rocker arm) are in the unactuated state, the second gas exchange valve is located completely outside the second valve actuation range, in particular completely outside the aforementioned groove of the second valve actuation range. Additionally, in the disassembly position and when the rocker arm and the second rocker arm (brake rocker arm) are in the unactuated state, the distance along the first actuating device between the second rocker arm (brake rocker arm) and the valve cap remaining on the first gas exchange valve when the valve manifold is moved into the disassembly position is greater than the extent of the collar.This allows the valve bridge to be disassembled in a particularly simple, time-saving, and cost-effective manner to provide sufficient access to the injector mounting without having to disassemble the valve train excessively or completely. Specifically, it is sufficient to disassemble the aforementioned assembly to create adequate access to the mounting. Since the assembly can be assembled and disassembled as a whole, it can be easily, quickly, and cost-effectively removed and then reassembled.

[0022] To facilitate particularly simple maintenance and repair of the internal combustion engine, it has proven advantageous for the valve cap to penetrate both length sections and thus the through-opening along the direction of actuation, especially completely. Therefore, the valve cap penetrates the first length section and the second length section.

[0023] A third aspect of the invention relates to an internal combustion engine, preferably designed as a reciprocating piston engine, for a motor vehicle, wherein the internal combustion engine according to the third aspect has at least one valve train according to the second aspect. Advantages and advantageous embodiments of the first aspect and the second aspect are to be regarded as advantages and advantageous embodiments of the third aspect and vice versa.

[0024] Further advantages, features, and details of the invention will become apparent from the following description of preferred embodiments and from the drawings. The features and combinations of features mentioned above in the description, as well as those mentioned below in the figure description and / or shown in the figures alone, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention.

[0025] The drawing shows in: Fig. 1 partial schematic front view of a valve train according to the invention; Fig. 2. Partially shown, another schematic front view of the valve train; Fig. 3. Partially a schematic and perspective side view of the valve train; Fig. 4. Partially a schematic and perspective top view of the valve train; Fig. 5 a schematic perspective view of a first embodiment of a valve bridge of the valve train; Fig. 6 a schematic top view of the valve bridge according to Fig. 5; Fig. 7 a schematic sectional view of the valve bridge according to Fig. 6 along a in Fig. 6 shown section line A1-A1; Fig. 8 a schematic exploded view in a top view of the valve bridge according to the first embodiment; Fig. 9 a schematic sectional view of the valve bridge according to Fig. 8 along a in Fig. 8 shown section line A2-A2; Fig. 10 a schematic perspective view of a second embodiment of the valve bridge; Fig. 11 a schematic top view of the valve bridge according to Fig. 10; Fig. 12 a schematic sectional view of the valve bridge according to Fig. 11 along a in Fig. 11 shown section line A3-A3; Fig. 13 a schematic exploded view in a top view of the valve bridge according to the second embodiment; Fig. 14 a schematic sectional view of the valve bridge according to Fig. 13 along a in Fig. 13 shown section line A4-A4; and Fig. 15 a schematic sectional view of a valve cap.

[0026] In the figures, identical or functionally equivalent elements are provided with the same reference numerals.

[0027] Fig. Figure 1 shows a schematic front view of a valve train 10 for an internal combustion engine designed as a reciprocating piston engine of a motor vehicle. The motor vehicle is preferably a car, in particular a commercial vehicle, and in its fully manufactured state comprises the internal combustion engine, also referred to as an internal combustion engine, by means of which the motor vehicle can be propelled. The internal combustion engine, not shown in detail, has at least one cylinder in which combustion processes take place during firing operation of the internal combustion engine. The cylinder is formed, for example, by a crankcase of the internal combustion engine. Furthermore, the internal combustion engine includes, for example, a cylinder head, which is formed separately from the crankcase and connected to it, and which forms a combustion chamber roof associated with the cylinder.The cylinder and the combustion chamber roof each partially form a combustion chamber. The combustion chamber is also partially formed by a piston, which is arranged to move translationally within the cylinder.

[0028] The valve train 10 is shown as an example for one cylinder and includes a camshaft 12, which is rotatably mounted on the cylinder head and thus rotatable about an axis of rotation relative to the cylinder head. The camshaft 12 has a first cam 14 and a second cam 16. The valve train 10 also includes a first gas exchange valve 18 and a second gas exchange valve 20, which are assigned to the same cylinder and are therefore common to the aforementioned cylinder. The gas exchange valves 18 and 20 are, for example, designed as exhaust valves. Each gas exchange valve 18 or 20 is associated with a gas channel, for example, formed or limited by the cylinder head, which is, for example, an exhaust port. The respective gas exchange valve 18 or 20 is translationally movable between at least one closed position and at least one open position relative to the cylinder head.In the respective closed position, the respective gas exchange valve 18 or 20 closes the corresponding exhaust port. In the respective open position, however, the respective gas exchange valve 18 or 20 opens the corresponding exhaust port, allowing gas initially located in the cylinder to flow out of the cylinder via the opened exhaust port. The respective gas exchange valve 18 or 20 is in a Fig. The first direction of movement, illustrated by arrow 22, is from the respective closed position to the respective open position relative to the cylinder head. Each gas exchange valve 18 or 20 is associated with a spring 24 or 26, also referred to as a return spring. When the respective gas exchange valve 18 or 20 is moved from the respective closed position to the respective open position, and thus moved relative to the cylinder head in the first direction of movement 22, the respective spring 24 or 26 is tensioned, in particular compressed. Consequently, the respective spring 24 or 26 provides a spring force that acts in the opposite direction to the first direction of movement 22. Fig. The second direction of movement, illustrated by arrow 28, is effective. By means of the respective spring force, the respective gas exchange valve 18 or 20 can be moved translationally in the second direction of movement 28 from the respective open position to the respective closed position and, in particular, held in the respective closed position.

[0029] The valve train 10 has a rocker arm shaft 30 and a first rocker arm 32, which is also referred to as the exhaust rocker arm. The first rocker arm 32 comprises a base body 34, an adjusting element 36 designed in this case as an adjusting screw, and a locking element 38 designed in this case as a lock nut. The adjusting element 36 is, for example, arranged along a Fig. The adjusting element 36, illustrated by a double arrow 40 and running parallel to the first direction of movement 22 and parallel to the second direction of movement 28, is translationally movable relative to the base body 34. This allows the adjusting element 36 to be moved along the adjusting direction 40 relative to the base body 34 into different positions, in which the adjusting element 36 is fixed or can be fixed relative to the base body 34 by means of the counter element 38. The adjusting element 36 is, for example, designed as an adjusting screw and screwed into the base body 34. If the adjusting screw 36 is, for example, turned in a first direction of rotation relative to the base body 34, the adjusting screw 36 is thereby moved translationally in the first direction of movement 22 relative to the base body 34.For example, if the adjusting screw 36 is turned in a second direction of rotation opposite to the first direction of rotation relative to the base body 34, the adjusting screw is thereby moved translationally in the second direction of movement 28 opposite to the first direction of movement 22 relative to the base body 34. The locking element 38 (lock nut) serves, for example, to secure the adjusting screw 36 against rotations relative to the base body 34 and thus against translational adjustment relative to the base body 34 and along the adjustment direction 40. A valve clearance, known per se, can be adjusted using the adjusting element 36.

[0030] The valve train 10 also has a valve bridge 42 common to the gas exchange valves 18 and 20 and preferably formed in one piece, wherein Fig. 5 to 9 a first embodiment and Fig. Figures 10 to 14 illustrate a second embodiment of the valve bridge 42. In this embodiment, the gas exchange valves 18 and 20 can be actuated via the valve bridge 42 by means of the first cam 14 via the first rocker arm 32 and are thereby translationally movable in the first direction of movement 22 and second direction of movement 28 relative to the cylinder head and relative to the rocker arm axis 30.

[0031] How particularly good in combination with Fig. 5 and with Fig. As can be seen in Figure 9, the valve bridge 42 has a bridge actuation area 44, via which the valve bridge 42 can be actuated by means of the first rocker arm 32 and is thereby translationally movable in a direction parallel to the directions of movement 22, 28 relative to the cylinder head and relative to the rocker arm axis 30. Furthermore, the valve bridge 42 has a first valve actuation area 46, which is spaced apart from the bridge actuation area 44, particularly in a longitudinal extension direction 50 of the valve bridge 42. Via the first valve actuation area 46, the first gas exchange valve 18 can be actuated by means of the valve bridge 42 and is thereby translationally movable in the first direction of movement 22 from the closed position to the open position of the first gas exchange valve 18 relative to the rocker arm axis 30 and relative to the cylinder head.

[0032] The valve bridge 42 also has a second valve actuation area 48, which is spaced apart, particularly in the longitudinal direction 50 of the valve bridge 42, from the valve actuation area 46 and from the bridge actuation area 44. The longitudinal direction of the valve bridge 42 is illustrated by a double arrow 50, where the longitudinal direction 50 runs, for example, perpendicular to the directions of movement 22, 28 and to the adjustment direction 40. Via the second valve actuation area 48, the second gas exchange valve 20 can be actuated by means of the valve bridge 42 and is thereby translationally movable in the first direction of movement 22 from the closed position to the open position of the second gas exchange valve 20 relative to the rocker arm axis 30 and relative to the cylinder head.The longitudinal extension direction 50 thus runs perpendicular to the gas exchange valves 18, 20, whereby the bridge actuation area 44 is provided along the longitudinal extension direction 50 between the first valve actuation area 46 and the second valve actuation area 48 on the valve bridge 42.

[0033] Out of Fig. Figure 4 shows that an injector 52 is also assigned to the cylinder. Fuel, particularly liquid fuel, can be introduced into the cylinder, especially directly injected, to operate the internal combustion engine by means of the injector 52. The injector 52 is attached to the cylinder head by means of a fastening 54, preferably designed as a screw connection. Since the fastening 54 is designed as a screw connection, it is also referred to as an injector fastening.

[0034] In the fully and completely manufactured state of the motor vehicle, and thus of the internal combustion engine and in particular of the valve train 10, the fastening 54 is overlapped or covered by the valve bridge 42, especially in the upward direction of the vehicle and / or in the upward direction of the internal combustion engine. Therefore, the fastening 54 is not accessible to a person wishing to service or repair the internal combustion engine when the engine is fully and completely manufactured.

[0035] In order to create sufficient accessibility to the fastening 54 in a particularly simple and therefore time- and cost-effective manner, and consequently to be able to service and / or repair the internal combustion engine in a particularly simple and therefore time- and cost-effective manner, the first valve actuation area 46 - such as well Fig. 9 and Fig. As can be seen in Figure 14, a through opening 56 is visible, which is continuous along the directions of movement 22, 28. Furthermore, the through opening 56 has a first length section L1, in which the through opening 56 extends along its, for example, in Fig. The circumferential direction 5, illustrated by a double arrow 58 and extending around the directions of movement 22, 28, is completely and thus uninterruptedly closed. Furthermore, the passage opening 56 has a second length section L2 that directly adjoins the first length section L1 in the first direction of movement 22 ( Fig. 7 and Fig. 12). In the second length range L2, the passage opening 56 points along its circumferential direction 58 at exactly one point S1 in a direction perpendicular to the directions of movement 22, 28 and, for example, in Fig. 5 and Fig. The direction 60, illustrated by an arrow 60 and also referred to as the first opening direction, opens a longitudinal opening 61. The first opening direction 60 runs parallel to the longitudinal extension direction 50.

[0036] The through-opening 56 has a smaller diameter in the first length section L1, viewed in the circumferential direction 58, than the second length section L2. Thus, the length section L1 forms a collar 62, on which the second length section L2 forms in the first direction of movement 22.

[0037] The second valve actuation area 48 shows - as for example, good Fig. 7 and Fig. As can be seen in Figure 12, a groove 63 is present. The groove 63 is formed along the longitudinal direction 50, perpendicular to the directions of movement 22 and 28, in the second valve actuation area 48 of the valve bridge 42. The groove 63 is completely closed in the second actuation direction 28 and thus open in the first direction of movement 22 to accommodate the gas exchange valve 20. The groove 63 is open at exactly one second location S2 in a second opening direction perpendicular to the actuation directions 22 and 28, as illustrated by an arrow 64. At this second location S2, the groove 63 therefore has a groove opening 66. Furthermore, the valve bridge 42 itself is formed in one piece.

[0038] The valve train 10 has a valve cap 68 that is separate from the gas exchange valves 18 and 20, separate from the first rocker arm 32, and separate from the valve bridge 42. The first gas exchange valve 18 can be actuated by means of a second rocker arm 70 provided in addition to the rocker arm 32, while the second gas exchange valve 20 is not actuated by the second rocker arm 70. The second rocker arm 70 is pivotably mounted on the rocker arm axis 30 and is thus pivotable about the aforementioned pivot axis relative to the rocker arm axis 30 and relative to the first rocker arm 32. The second rocker arm 70 is actuated by the second cam 16, meaning that only the first gas exchange valve 18 is translationally movable in the first direction of movement 22 and the second direction of movement 28 relative to the cylinder head and relative to the rocker arm axis 30.The second rocker arm 70 is a so-called brake rocker arm, by means of which the gas exchange valve 18 can be actuated in such a way that engine braking, and thus an engine brake designed as a decompression brake, of the internal combustion engine is possible. The valve cap 68 completely penetrates the length ranges L1 and L2 along the actuation directions 22, 28.

[0039] Especially good from the Fig. 5 and Fig. Figure 7 shows that in the first embodiment of the valve bridge 42, the valve cap 68, which is formed separately from the valve bridge 42, is held on the valve bridge 42 by means of at least or exactly one first fastening element 72, such that the valve bridge 42 and the valve cap 68, considered separately, form a self-assembled assembly 74 that can be mounted and dismounted as a whole. In the assembly 74, the valve cap 68 is held on the valve bridge 42 independently of the gas exchange valves 18 and 20, independently of the first rocker arm 32, and independently of the second rocker arm 70. Fig. 8 and Fig. Figure 9 clearly shows that the first fastening element 72 is formed separately from the valve cap 68 and separately from the valve bridge 42. In the first embodiment, the first fastening element 72 is, for example, an open wire ring, in particular a clamping ring, made of a metallic material. In the assembled state of the assembly 74, it is particularly evident that Fig. 5 and Fig. 7 can be seen that the fastening element 72 is received in the through-opening 56 in the second length section L2 in a circumferential groove 76. As can be seen from Fig. As can be seen in Figure 5, the wire ring 72 passes through the longitudinal opening 61. The wire ring 72 can therefore be removed, for example, using a suitable tool, when the valve train 10 is fully assembled. The valve cap 68 is slidably held in the fastening element 72 in the directions of movement 22 and 28.

[0040] In Fig. 15 shows the valve cap 68, which for the first embodiment according to the Fig. 5 to 9 and for the second embodiment according to the Fig. 10 to 14. In a lower region 78 of the valve cap 68, a receiving opening 80 for the first gas exchange valve 18 is provided. The first gas exchange valve 18 is received in the receiving opening 80 with essentially no play and is supported against the valve cap 68 in the first direction of movement 22. The valve cap 68 also has a circumferential collar 84 projecting from its lower region 78 and its upper region 82. The collar 84 interacts with the flange 62 such that, when the valve bridge 42 is actuated by means of the first rocker arm 32 in the direction of movement 22, the valve cap 68, with its collar 84, bears against the flange 62 of the first valve actuation area 46.The fastening element 72 of the first embodiment prevents the valve cap 68 from falling out of the through-opening 56 of the valve bridge 42 after the assembly of the assembly unit 74, in that the valve cap 68 is supported on the fastening element 72 via its collar 84.

[0041] The valve cap 68 also has a ring-shaped area 86 projecting from the upper area 82 in the direction of movement 28 and in the circumferential direction 58. The ring-shaped area 86 and the end of the upper area 82 form the brake rocker arm actuation area 88. The brake rocker arm 70 (second rocker arm) engages the brake rocker arm actuation area 88. The ring-shaped area 86 is only large enough to allow the valve cap 68 to be inserted through the through-opening 56 of the first valve actuation area 46, so that the collar 84 of the valve cap 68 rests against the flange 62 of the first valve actuation area 46 of the valve bridge 42.

[0042] The collar 84 also has a circumferential, essentially spherical surface contour 90 on its upper region 82 of the valve cap 68. This allows tilting of the valve bridge 42 to be compensated for when only the first gas exchange valve 18 is actuated by means of the second rocker arm 70, or it allows the collar 84 to continue to be subjected to at least circumferential, linear contact with the collar 62. The valve cap 68 is rotationally symmetrical.

[0043] As an alternative to the first embodiment, the Fig. Figures 10 to 12 show a second embodiment in which, instead of the first fastening element 72, a second fastening element 92 can be provided in the upper region 82 of the valve cap 68. The second fastening element 92 encompasses the upper region 82 of the valve cap 68 and rests against the circumference of the upper region 80. The ring section 86 prevents the second fastening element 92 from slipping off the valve cap 68. The second fastening element 92 is, for example, designed as an O-ring, the O-ring being large enough that the valve cap 68 with the O-ring 92 installed cannot fall out of the through-opening 56b and thus forms the assembly 74 in the second embodiment. The second fastening element 92 can be removed with a suitable tool when the valve train 10 is fully assembled.

[0044] Out of Fig. 9 and Fig. Figure 14 shows that the longitudinal opening 61 at the open point S1 is completely covered or overlapped in the directions of movement 22, 28 by a collar 62 of the valve bridge 42 arranged in the first length section L1. The collar 62 has an extension X1 extending along the directions of movement 22, 28.

[0045] Out of Fig. 1 and Fig. 2 it can be seen that the valve bridge 42 in the second direction of movement 28 relative to the gas exchange valves 18 and 20, relative to the valve cap 68 and relative to the rocker arms 32 and 70 into a Fig. 2 shown and labelled D is dismountable, in which, in the unactuated state of the rocker arms 32 and 70, the valve bridge 42 and the gas exchange valves 18 and 20, the second gas exchange valve 20 is arranged completely outside the second valve actuation area 48, in particular completely outside the groove 63, and a distance X2 extending along the directions of movement 22, 28 ( Fig. 2) between the second rocker arm 70 and the brake rocker arm actuation area 88 of the valve cap 68 greater than the extent X1 ( Fig. 9 and Fig. 14) of the Federal Republic of Germany 62.

[0046] Furthermore, in Fig. 7 the focus of the assembly, which is also referred to as the assembly and includes, for example, the fastening element 72, is designated SP.

[0047] The valve train may also include a spring clip 94 and a rocker arm spring 96, in particular for the brake rocker arm 70 ( Fig. 3 and Fig. 4) The rocker arm spring 96 is supported on the spring bracket 94, the rocker arm spring 96 acting on the second rocker arm 70 in such a way that the second rocker arm 70 remains in contact with the second cam 16.

[0048] The brake rocker arm 70, for example, is a hydraulic brake rocker arm. This means, in particular, that the brake rocker arm 70 can be hydraulically switched between a deactivated and an activated state. In the deactivated state of the brake rocker arm 70, a piston 98, also referred to as a brake piston, is retracted, such that, despite pivoting or actuating the brake rocker arm 70 by means of the second cam 16 of the camshaft 12, the gas exchange valve 18 is not actuated via the valve cap 68 by the brake rocker arm 70. To switch the brake rocker arm 70 from the deactivated state to the activated state, the piston 98 is extended. Thus, in the activated state of the brake rocker arm 70, the piston 98 is extended.When the brake rocker arm 70 is pivoted in the activated state, the first gas exchange valve 18 is actuated by means of the brake rocker arm 70 via the extended piston 98 and the valve cap 68, while the second gas exchange valve 20 is not actuated. The distance X2 refers in particular to a distance extending along the actuation directions 22, 28 between the piston 98 and the valve actuation area 46 or brake rocker arm actuation area 88 of the valve cap 68.

[0049] The following is a summary description of the valve train 10 and, in particular, its function: the internal combustion engine 10 has the aforementioned engine brake, which also functions as a decompression brake. This brake is implemented via the separate second rocker arm 70, provided in addition to the first rocker arm 32. For example, the rocker arm 70 transmits a brake valve stroke of the second cam 16 via the piston 98 to the valve cap 68 and, via this, to the gas exchange valve 18. The valve bridge 42 is designed for fired operation, also referred to as fired operation, particularly exhaust operation, such that the valve cap 68 and, via the valve cap 68, the first gas exchange valve 18 can be actuated independently of the valve bridge 42 and, respectively, independently of the gas exchange valve 20.However, replacing injector 52 using conventional methods can be very complex or even impossible, as access to the mounting 54 of injector 52 is obstructed by the valve bridge 42 and therefore impossible. Thus, with conventional solutions, if injector 52 is to be replaced, the valve train 10 must first be removed.

[0050] In the valve train 10, replacing the injector 52 is now possible in a particularly simple manner. For this purpose, the adjusting element 36 (adjusting screw) is turned back or retracted, i.e., moved away from the valve bridge 42 in the direction of movement 28. Using the adjusting element 36, a clearance between the rocker arm 32 and the valve bridge 42, in particular the bridge actuation area 44, can be set, so that the adjusting element 36 can be moved along the adjustment direction 40 relative to the base body 34 of the first rocker arm 32 (exhaust rocker arm). After turning back or moving the adjusting element 36 away from the valve bridge 42, the valve bridge 42 is raised, i.e., moved in the second direction of movement 28 relative to the gas exchange valves 18 and 20, until the second gas exchange valve 20 is completely moved out of the groove 63. Fig. 2) Now the valve bridge 42 can be rotated or pivoted around the valve cap 68, for example, in the direction of the rocker arm axis 30, until the valve bridge 42 comes into contact with the rocker arm axis 30 or with the first rocker arm 32. Then - as is particularly good from Fig. 3 and Fig. 4 can be seen - the valve bridge 42 is arranged without overlap for fastening 54, so that the fastening 54 is easily accessible and the injector 52 can be replaced easily, quickly and cost-effectively.

[0051] In firing mode, the rocker arm 32, referred to as the exhaust rocker arm, actuates an exhaust stroke movement caused by the cam 14, also referred to as the exhaust cam, via the adjusting element 36 and the valve bridge 42 to both gas exchange valves 18 and 20. If the engine brake is activated, the brake rocker arm 70 (second rocker arm) actuates the first gas exchange valve 18, but not the second gas exchange valve 20, by transmitting a brake stroke movement caused by the cam 16, also referred to as the brake cam, via the hydraulically extended piston 98 and the valve cap 68 to the first gas exchange valve 18, and in relation to the gas exchange valves 18 and 20, exclusively to the first gas exchange valve 18.Since the piston 90 is retracted when the internal combustion engine is deactivated and at a standstill, a clearance in the form of the distance X2 exists between the piston 98 and the valve cap 68, in particular its end at the brake rocker arm actuation area 88. The distance X2 exists in particular when the second rocker arm 70 is on a base circle of the cam 16, i.e., when it is unactuated.

[0052] To access the mounting 54 of the injector 52, the valve bridge 42 remains on the valve cap 68 and is only pivoted or rotated laterally until the valve bridge 42 comes into contact with the rocker arm axis 30. This provides sufficient access to the mounting 54.

[0053] The clearance X2 is used to remove the valve bridge 42. However, excessive or complete disassembly of the valve train 10 can also be avoided when removing the valve bridge 42.

[0054] With regard to the removal of the valve bridge 42, the locking element 38 is first loosened, whereupon the adjusting element 36 is completely or maximally turned back, i.e., moved away from the valve bridge 42 in the direction of movement 28. Then, in the first embodiment, the first fastening element 72 is removed ( Fig. 8 and Fig. 9) and in the second embodiment the second fastening element 92 is removed ( Fig. 13 and Fig.14) to release the retention of the valve cap 68 on the valve bridge 42 caused by the respective fastening elements 72 and 92. The valve bridge 42 is then moved translationally in the second direction of movement 28 relative to the gas exchange valves 18 and 20, and in particular relative to the valve cap 68, i.e., raised, until the valve bridge 42 comes to rest against the adjusting element 36 and until the gas exchange valve 20, in particular its end, is completely outside the groove 63. The valve bridge 42 is then tilted so that the valve bridge 42, in particular its end with the collar 62 located on the valve actuation area 46, can be pulled out laterally with the collar 62 between the second rocker arm 72 with its piston 98 and the brake lever actuation area 88 of the valve cap 68, since the extension X1 is less than the distance X2.The longitudinal opening 61 of the open section S1 extends circumferentially 58 preferably far enough that the valve bridge 42 can be pulled off the valve cap 68, since the valve cap 68 remains on the first gas exchange valve 18. The open sections S1 and S2 of the valve bridge 42 are arranged diametrically or at least substantially diametrically to each other along the longitudinal direction 50 of the valve bridge 42. In particular, it can be seen from the figures that the valve actuation areas 46 and 48 are arranged at respective ends of the valve bridge 42, which are spaced apart from each other along the longitudinal direction 50 of the valve bridge 42.

[0055] Another advantage of the valve train 10 is that, when assembling the valve train 10, only one component, in the form of the assembly 74, is placed on both ends of the gas exchange valves 18 and 20. In other words, the valve cap 68, the first fastening element 72 or the second fastening element 92, and the valve bridge 42 are mounted simultaneously, so that it is not necessary to first place the valve cap 68 onto the gas exchange valve 18 and then separately place the valve bridge 42 onto the valve cap 68, which was previously placed on the first gas exchange valve 18.

[0056] Furthermore, it is preferably provided that the center of gravity SP of the assembly comprising the valve bridge 42 and the valve cap 68, and preferably the fastening element 72, is located, in particular centrally, between the two gas exchange valves 18 and 20. This prevents or at least minimizes tilting of the valve bridge 42 caused by inertial forces and unequal valve movement of the gas exchange valves 18 and 20 during firing operation.

[0057] During engine braking, opening the first gas exchange valve 18 used for the engine brake can displace a support of the valve bridge 42, which can lead to lateral tilting with each brake stroke. To prevent excessive edge loading, for example of the valve bridge 42 and / or the valve cap 68, at least the force application surfaces of the valve cap 68 (collar 84) are designed with the previously described spherical surface contour 90.

[0058] Furthermore, since the groove 63 is open at exactly one point S2 along its circumferential direction and closed elsewhere, the groove 63 is a semi-open groove. This allows the valve bridge 62 to be used as a uniform valve bridge across different displacement classes. The semi-open groove 63 provides a degree of freedom with regard to the distance between the gas exchange valves 18 and 20, particularly along the second opening direction 64. In other words, the gas exchange valves 18 and 20 can be arranged at different distances from each other, particularly along the second opening direction 64. Reference symbol list 10 Valve train 12 Camshaft 14 first cam 16 second cam 18 first gas exchange valve 20 second gas exchange valve 22 first direction of movement 24 springs 26 springs 28 second direction of movement 30 rocker arm axle 32 first rocker arm 34 Basic bodies 36 Adjustment element 38 Counter element 40 Direction of adjustment 42 Valve bridge 44 Bridge operating range 46 first valve actuation range 48 second valve actuation range 50 Longitudinal direction 52 injectors 54 Fastening 56 Passage opening 58 Circumferential direction 60 first opening direction 61 Longitudinal opening 62nd Federal Government 63 Nut 64 second opening direction 66 Groove opening 68 Valve cap 70 second rocker arm 72 first fastening element 74 building units 76 Nut 78 lower range 80 aperture 82 upper area 84 collars 86 ring area 88 Brake rocker arm actuation range 90 Surface contour 92 second fastening element 94 spring clips 96 rocker arm spring 98 pistons D Disassembly position L1 first length range L2 second length range S1 first position S2 second position SP focus X1 extension X2 distance

Claims

[1] Valve train (10) for an internal combustion engine, comprising a first gas exchange valve (18), a second gas exchange valve (20), a first rocker arm (32) and a common valve bridge (42) for the gas exchange valves (18, 20), via which the gas exchange valves (18, 20) can be actuated by means of the first rocker arm (32) and thereby moved translationally in a first direction of movement (22), wherein the valve bridge (42) comprises: - a bridge actuation area (44) via which the valve bridge (42) can be actuated by means of the first rocker arm (32) and thereby moved translationally parallel to the first direction of movement (22), - a first valve actuation area (46) via which the first gas exchange valve (18) can be actuated by means of the valve bridge (42) by actuating the valve bridge (42), - a second valve actuation area (48) via which the second gas exchange valve (20) can be actuated by means of the valve bridge (42) by actuating the valve bridge (42), wherein the first valve actuation area (46) has a through-opening (56) which is continuous along the first actuation direction (22), - has a first length section (L1) in which the passage opening (56) is completely closed along its circumferential direction (58), and - has a second length section (L2) directly adjoining the first length section (L1) in the first actuation direction (22), in which the through-hole (56) is open at a first location (S1) along its circumferential direction (58) in a first opening direction (60) perpendicular to the actuation direction (22), wherein the second valve actuation area (48) has a groove (63) which is open at a second location (S2) in a second opening direction (64) perpendicular to the first actuation direction (22) and opposite to the first opening direction, wherein the groove (63) is completely closed in a second actuation direction (28) opposite to the first actuation direction (22), characterized by, that a valve cap (68) is provided, which is designed separately from the gas exchange valves (18, 20), from the rocker arm (32) and from the valve bridge (42), via which the first gas exchange valve (18) can be actuated by means of a second rocker arm (70) of the valve train (10), wherein: - the valve bridge (42) and the valve cap (68) form a self-contained assembly (74) that can be mounted as a whole, in which the valve cap (68) is held on the valve bridge (42) independently of the gas exchange valves (18, 20) and independently of the rocker arms (32, 70); and / or - the open area (S1) in a second actuation direction (28) opposite to the first actuation direction (22) is covered by a collar (62) of the valve bridge (42) arranged in the first length region (L1), wherein the collar (62) has an extension (X1) extending along the first actuation direction (22), and wherein the valve bridge (42) is displaceable in the second direction of movement (28) opposite to the first actuation direction (22) relative to the gas exchange valves (18, 20), the valve cap (68) and the rocker arms (32, 70) into a disassembly position (D) in which, in the unactuated state, the rocker arms (32, 70) and the gas exchange valves (18, 20) are: ◯ the second gas exchange valve (20) is arranged completely outside the second valve actuation range (48), and ◯ a distance (X2) running along the first direction of actuation (22) between the second rocker arm (70) and the valve cap (68) remaining on the first gas exchange valve (18) when the valve bridge (42) is moved is greater than the extent (X1) of the collar (62). [2] Valve train (10) according to claim 1, characterized by , that the valve cap (68) penetrates the length ranges (L1, L2) along the first actuation direction (22). [3] Internal combustion engine for a motor vehicle, comprising at least one valve train (10) according to claim 1 or 2.

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