DE102021101374A1 - Lever arrangement for a valve drive of an internal combustion engine - Google Patents

Abstract

The invention relates to a lever arrangement for a valve drive of an internal combustion engine, having at least one first lever (3) and at least one second lever (4), the levers (3, 4) being arranged next to one another on a common pivot axis (2) and being pivoted relative to one another and can be coupled for switching, at least one stop (1) being provided for limiting a pivoting movement of the levers (3, 4), characterized in that the stop (1) in the region of the pivot bearing surfaces (5, 6) of the levers (3, 4 ) is arranged.

Description

The invention relates to a lever arrangement for a valve drive of an internal combustion engine according to the type defined in more detail in the preamble of claim 1.

For example, is off DE 10 2006 034 951 A1 a valve train for an internal combustion engine with a switchable rocker arm assembly with a plurality of rocker arms is known, which are pivotally mounted on a stationary rocker arm shaft. Several positioning aids ensure that the toggle levers are aligned for shifting in such a way that alternating locking and unlocking is possible. A positioning aid arranged on a rocker arm is designed as a stop which is supported on a camshaft.

The invention is therefore based on the object of simplifying a lever arrangement of the aforementioned type with regard to its construction and its production and of making it inexpensive.

The object is solved by the features of claim 1. Further advantageous and claimed configurations result from the respective dependent claims, the description and the drawings.

Thus, a lever arrangement for a valve train of an internal combustion engine is proposed with at least one first lever and at least one second lever, the levers being arranged next to one another on a common pivot axis and pivoted to one another and coupled for shifting. At least one stop is provided to limit a pivoting movement of the levers. In order to keep the component tolerance chain at the stop as small as possible in relation to the bearing axis, the stop is arranged in the area of the pivot bearing surfaces of the lever. This enables a stop of simple construction which can be produced cost-effectively with a high degree of accuracy with a reduced component tolerance chain.

As a result, precise positioning of the levers and precise and trouble-free switching of the levers in an end position that is precisely defined at the stop in a basic state of the levers is ensured.

The stop can be formed in a particularly simple and space-saving manner by a projection on a first lever and a recess on a second lever, such that the projection engages in the recess in a pivotable manner and can be placed in the recess on the second lever.

In a particularly advantageous manner, the projection and the recess can be embodied on the pivot bearing surfaces of the levers.

It is also particularly advantageous if the projection forms an extension of a pivot bearing surface on the first lever. In this way, the introduction of force into the pivot bearing of the lever can be controlled by the arrangement of the projection and the pivot bearing surface on the first lever can be enlarged, as a result of which the surface pressures can be reduced. The stop can thus be arranged at any point on the bearing diameter and can therefore be easily adapted in particular to the installation and operating conditions. At the same time, an optimal reduction of the component tolerance chain at the stop in relation to the swivel or bearing axis is made possible. In addition, the stop can be integrated into the pivot bearings of the levers in a particularly space-saving and compact manner.

A further simplified embodiment of the invention can be achieved in that the projection on the first lever is in the form of a ring segment and forms the extension of the pivot bearing surface on the first lever on the inside diameter. The projection can be designed like a claw on the first lever for engagement on the second lever. At the same time, the projection preferably forms a first stop face for contact with the second lever on at least one end face oriented in the pivoting direction. It is also possible to provide a stop surface on two end faces of the projection, each aligned in one pivoting direction, to limit the pivoting movement in both pivoting directions.

The recess can be designed in a simple manner as a groove on the pivot bearing surface on the second lever and can form at least one second stop surface on at least one of its ends in at least one pivot direction for the projection to rest against. It is also conceivable to provide a correspondingly aligned stop surface at both ends of the recess in order to limit the pivoting movement in both pivoting directions.

In a further particularly preferred embodiment of the invention, the first lever with the pivot bearing surface and the extension thereof formed on the projection and the second lever with the pivot bearing surface are each slide-mounted on the outer diameter of the pivot bearing axis. As a result, the component tolerance chain at the stop in relation to the bearing axis and thus the manufacturing effort can be minimized and the accuracy can be further increased.

The projection is preferably formed in one piece with the first lever, so that the extension of the pivot bearing surface formed by the projection is seamlessly connected to the latter.

The recess on the second lever can be arranged in a further advantageous manner in a region of the pivot bearing surface in which lower surface pressures occur during operation.

Pivot bearing bores are preferably provided on the levers for mounting them on the pivot axis and locking bores are provided to form a coupling mechanism for coupling the levers. A further reduction in the component tolerance chain on the stop and thus a further simplification of the production and increase in the accuracy of the same is made possible if the stop forms at least one first stop surface on the first lever and at least one second stop surface on the second lever in such a way that the stop surfaces are each in lie in a plane with the central axis of the pivot bearing bores and with the respective central axis of the locking bores.

In a further particularly preferred embodiment of the invention, the first lever forms a valve-side rocker arm with at least one valve contact section for actuating at least one gas exchange valve of the internal combustion engine, and the second lever forms a cam-side rocker arm with at least one pickup element for pickup of a cam lift movement of a camshaft of the internal combustion engine. In this way, the higher loads occurring in the pivot bearing of the rocker arm during valve actuation can be better absorbed by the arrangement of the projection on the pivot bearing surface of the valve-side rocker arm. At the same time, this enables the recess to be formed on the pivot bearing surface of the rocker arm on the cam side, which is subjected to less stress during operation. As a result, a cost-effective and space-saving stop with high accuracy can be implemented in a switchable rocker arm arrangement that can be driven by a camshaft of the internal combustion engine and has at least two rocker arm arms that are mounted pivotably relative to one another on a common pivot axis for a valve drive of the internal combustion engine, with the rocker arm arrangement having only one pivot axis.

The lever arrangement can also include several groups arranged on a common pivot axis, each with at least one first lever and at least one second lever, the levers of each group being arranged next to one another on the pivot axis and pivoted relative to one another.

• 1 eine Seitenansicht einer erfindungsgemäßen Hebelanordnung für einen Ventiltrieb einer Brennkraftmaschine in einem ersten Betriebszustand,
• 2 eine Seitenansicht der Hebelanordnung in einem zweiten Betriebszustand,
• 3 die Hebelanordnung in einer perspektivischen Darstellung,
• 4 eine perspektivische Einzelansicht eines ersten Hebels,
• 5 eine perspektivische Einzelansicht eines zweiten Hebels.

Further claimed features of the invention result from the following description and from the drawings, in which several exemplary embodiments of the invention are shown in simplified form. Show it:

• 1 a side view of a lever arrangement according to the invention for a valve train of an internal combustion engine in a first operating state,
• 2 a side view of the lever arrangement in a second operating state,
• 3 the lever arrangement in a perspective view,
• 4 a perspective detail view of a first lever,
• 5 a perspective detail view of a second lever.

In the 1 until 3 Lever arrangement according to the invention for a valve train of an internal combustion engine shown by way of example has a first lever 3 and a second lever 4, the levers 3, 4 being arranged next to one another on a common pivot axis 2 and pivotably mounted relative to one another. A stop 1 serves to limit the pivoting movement in an end position of the levers 3, 4, which is precisely defined on the stop 1, in a basic state in which the levers 3, 4 can be coupled for switching. The levers 3, 4 are each slide-mounted via a pivot bearing surface 5, 6 of a pivot bearing on the outer diameter of the common pivot axis 2, such that the lever 3, 4 in the image plane of 1 are pivotable to each other. The pivot bearing surfaces 5, 6 are formed on the inner diameter of pivot bearing bores 3a, 4a on the levers 3, 4, on which the common pivot axis 2 is guided. Alternatively, the pivot bearing surfaces 5, 6 can also each be part of a roller bearing for the levers 3, 4.

A first lever 3 is designed as a valve-side rocker arm with a valve contact section 11 at a valve-side lever end for actuating at least one gas exchange valve, not shown, of the internal combustion engine. A second lever 4 serves as a cam-side rocker arm and is designed with a pick-up element 12, here a cam roller, on a cam-side lever end for picking up a cam lift movement from a camshaft 13 of the internal combustion engine. In this way, the lever arrangement forms a switchable rocker arm arrangement. In 1 the levers 3, 4 are switched in the decoupled state during a so-called stroke cut-off, in which the second lever 4 is in the idle stroke and no valve stroke for valve actuation can be transmitted. To reset the levers 3, 4 during idle hubs in the mutually non-pivoted basic state, restoring spring means (not shown) can be provided. 2 shows the levers 3, 4 in the coupled basic state for the transmission of a valve lift for valve actuation.

The stop 1 is arranged in the area of the pivot bearing surfaces 5, 6 of the levers 3, 4 and is formed by a projection 7 on the first lever 3 and a recess 8 on the second lever 4 ( 1 , 2 , 4 and 5 ). In this way, a high level of accuracy and precise positioning of the levers 3, 4 in the basic state is achieved on the stop 1 with a reduced component tolerance chain, based on the bearing axis 14, which also forms the central axis of the pivot bearing bores 3a, 4a, and reduced production costs. Malfunctions when shifting, in particular jamming of a coupling mechanism for coupling the levers 3, 4, especially when coupling but also when decoupling the levers 3, 4, are thus reliably avoided. Since the projection 7 pivotally engages in the recess 8 ( 1 ) a space-saving arrangement of the stop 1 is also achieved. To limit the pivoting movement, the projection 7 can be placed with a first stop surface 9 against a second stop surface 10 in the recess 8 ( 2 ). The projection 7 and the recess 8 are each formed on the pivot bearing surfaces 5, 6 of the levers 3, 4 ( 4 and 5 ), whereby a simple integration of the stop 1 in the pivot bearings of the levers 3, 4 is achieved.

The projection 7 reproduces it 4 an axial extension 7a of the pivot bearing surface 5 on the first lever 3 and is constructed in one piece with it. It protrudes axially in the manner of a claw on an edge of the pivot bearing surface 5 on a longitudinal side of the first lever 3 . The projection 7 has the shape of a ring segment and forms the extension 7a of the pivot bearing surface 5 on the inner diameter. The extension 7a follows seamlessly on the pivot bearing surface 5 and thus enlarges the latter on the first lever 3. The projection forms an end face aligned in a first pivoting direction 7 the first stop surface 9 for contact with the second lever 4. It is possible, but not absolutely necessary, to provide a stop surface for limiting the pivoting movement in the second pivoting direction on the further end face of the projection 7 aligned in the second pivoting direction. The first lever 3 is slide-mounted with the pivot bearing surface 5 and the extension 7a of the same formed on the inner diameter of the projection 7 on the outer diameter of the pivot axis 2 ( 2 and 3 ).

The projection 7 engages with the extension 7a of the pivot bearing surface 5 on the first lever 3 at the same height in the corresponding recess 8 on the pivot bearing surface 6 on the second lever 4 so that it can pivot ( 1 ). The recess 8 forms a clearance on the second lever 4 to allow the engaging projection 7 with the first lever 3 to pivot relative to the second lever 4 . The projection 7 can be placed with the first stop surface 9 on the second stop surface 10 in the recess 8 to limit the pivoting movement of the levers 3, 4 in the basic state ( 2 ).

The recess 8 is according to 5 and 1 on the second lever 4 corresponding to the projection 7 arranged axially opposite this and extends from the axial edge of the pivot bearing surface 6 . It is designed as an axially continuous groove on the lever 4 which, in a first pivoting direction, forms the second abutment surface 10 at a first end for the projection 7 to rest in the basic state of the levers 3 , 4 . In the second pivoting direction, the recess 8 extends in the circumferential or pivoting direction to a second end so far that the projection 7 with the first lever 3 is freely pivotable in the decoupled state of the levers 3, 4 during an idle stroke. It is possible, but not absolutely necessary, to limit the pivoting movement in the second pivoting direction by means of a stop surface at the second end of the recess 8.

The recess 8 is arranged in a region of the pivot bearing surface 6 which faces the upper side of the lever of the second lever 4 which, in the installed position, faces away from the gas exchange valve or from the cylinder head of the internal combustion engine ( 1 , 2 and 5 ). During operation, the lowest surface pressures occur there on the pivot bearing surface 6 on the second lever 4 .

in the in 1 shown decoupled state during an idle stroke, the levers 3, 4 are pivotable to each other in the image plane. In the decoupled state of the levers 3, 4, the projection 7 can be pivoted with the first lever 3 in the recess 8 until the basic state of the levers 3, 4 in the cam base circle phase is reached in a pivoting direction, as in 2 shown, and the projection 7 with the first stop surface 9 comes to rest against the second stop surface 10 at the end of the recess 8 .

To couple the levers in the end position defined on the stop 1 in the basic state of the levers 3, 4, a first locking hole 15 on the first lever 3 is aligned with a second locking hole 17 on the second lever 4 ( 2 , 4 and 5 ). As a result, in the cam base circle phase ( 2 ) a in the second locking bore 17 slidably arranged coupling element ment 16 with a coupling-side end over a slight axial air gap away in the opposite first locking hole 15 on the first lever 3 slidably. In this way, the levers 3, 4 are coupled and a cam lift movement picked up by the camshaft 13 on the second lever 4 in the illustrated cam lift phase can be transmitted to at least one gas exchange valve on the first lever 3 ( 2 ). To decouple the levers 3, 4 in the basic state, the coupling element 16 can be pushed back with the coupling-side end out of the first locking bore 15 into the second locking bore 17 in the cam base circle phase. The locking bores 15, 17 are each designed as through bores on the levers 3, 4 near the pivot bearing bores 3a, 4a and run axially parallel to the bearing axis 14 or to the central axis of the pivot bearing bores 3a, 4a. The coupling element 16, here a cylindrical coupling bolt, and the locking bores 15, 17 are part of a coupling mechanism, not shown, which can be switched by an actuator, not shown, preferably by an electric actuator. The actuation for coupling or decoupling can also take place in combination with prestressed spring means. The coupling mechanism described enables a so-called transverse locking of the levers 3, 4, ie transversely to the longitudinal axis thereof. The high accuracy of the stop 1 also allows the coupling mechanism, in particular the locking bores 15, 17, to be designed with low component tolerances, which means that the application of force to the coupling element 16 in particular can be optimized and wear during operation can be minimized.

The arrangement of the stop 1 is basically possible in any position on the circumference or on the diameter of the pivot bearing surfaces 5, 6. In 2 two further alternative arrangement possibilities of the stop 1 are shown, in which the tolerance accuracy of the stop 1 is further improved. The alternative possible arrangements for the stop 1', 1" are each identified by dashed lines. In both alternatives, the planar stop surfaces 9', 10' or 9", 10" each in a plane 23 indicated by a dashed line with the bearing axis 14 or the central axis of the pivot bearing bores 3a, 4a and the central axis 18 of the locking bores 15, 17 ( 1 , 2 , 4 and 5 ). In the basic state, alternative positioning of the stop 1', 1'' on the circumference or on the diameter of the pivot bearing surfaces 5, 6 in a clockwise direction is possible in a first variant at 3 o'clock and in a second variant at 9 o'clock ( 2 ).

The pivot axis 2 is fastened to a support 20 via screw connections 21 with an axis section 19 protruding from the first lever 3 ( 3 ). The actuator system for switching the coupling mechanism is at least partially accommodated in a housing section 22 of the carrier 20 . It is also conceivable to include parts of the coupling mechanism there. In this way, the levers 3, 4, the pivot axis 2, the coupling mechanism and the actuator together with the carrier 20 form a pre-assemblable switchable rocker arm unit, which can be connected via the carrier 20 to the screw connections 21 on the internal combustion engine, in particular on the cylinder head or another stationary component , is fastened in a simple manner.

Reference List

1

attack

1'

attack

1''

attack

2

pivot axis

3

lever

3a

pivot bearing bore

4

lever

4a

pivot bearing bore

5

pivot bearing surface

6

pivot bearing surface

7

head Start

7a

renewal

8th

recess

9

stop surface

9'

stop surface

9"

stop surface

10

stop surface

10'

stop surface

10"

stop surface

11

valve contact section

12

pick-up element

13

camshaft

14

Bearing axis, central axis

15

locking hole

16

coupling element

17

locking hole

18

central axis

19

axis section

20

carrier

21

screw connection

22

housing section

23

level

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102006034951 A1 [0002]

Claims (10)

Lever arrangement for a valve drive of an internal combustion engine, with at least one first lever (3) and at least one second lever (4), the levers (3, 4) being arranged next to one another on a common pivot axis (2) and being pivotably mounted relative to one another and being able to be coupled for shifting At least one stop (1) is provided to limit a pivoting movement of the levers (3, 4), characterized in that the stop (1) is arranged in the area of the pivot bearing surfaces (5, 6) of the levers (3, 4). lever arrangement claim 1 , characterized in that the stop (1) is formed by a projection (7) on the first lever (3) and a recess (8) on the second lever (4), such that the projection (7) fits into the recess (8 ) engages in a pivotable manner and can be placed in the recess (8) on the second lever (4). lever arrangement claim 2 , characterized in that the projection (7) forms an extension (7a) of a pivot bearing surface (5) on the first lever (3) and the recess (8) is executed on a pivot bearing surface (6) on the second lever (4). Lever arrangement according to one of claims 2 or 3 , characterized in that the projection (7) on the first lever (3) is designed protruding in the form of a ring segment and on the inner diameter an extension (7a) of a pivot bearing surface (5) on the first lever (3) and on at least one end face aligned in the pivoting direction forms at least one first stop surface (9, 9', 9") for abutment in the recess (8). Lever arrangement according to one of claims 2 until 4 , characterized in that the recess (8) is designed as a groove on the pivot bearing surface (6) of the second lever (4) and in at least one pivoting direction at least one of its ends has at least one second stop surface (10, 10', 10") for Plant of the projection (7) forms. Lever arrangement according to one of claims 3 until 5 , characterized in that the first lever (3) with the pivot bearing surface (5) and the extension (7a) of the same formed on the projection and the second lever (4) with the pivot bearing surface (6) are slide-mounted on the outer diameter of the pivot axis (2). Lever arrangement according to one of claims 3 until 6 , characterized in that the projection (7) is formed in one piece with the first lever (3), so that the projection (7) formed extension (7a) of the pivot bearing surface (5) adjoins the latter seamlessly. Lever arrangement according to one of claims 2 until 7 , characterized in that the recess (8) is arranged in a region of the pivot bearing surface (6) of the second lever (4) in which lower surface pressures occur during operation. Lever arrangement according to one of Claims 1 until 8th , characterized in that pivot bearing bores (3a, 4a) are provided on the levers (3, 4) to mount them on the pivot axis (2) and locking bores (3a, 4a) are provided to form a coupling mechanism for coupling the levers (3, 4). , wherein the stop (1) forms at least one first stop surface (9', 9") on the first lever (3) and at least one second stop surface (10', 10'') on the second lever (4), such that the stop surfaces (9', 9", 10', 10") each in a plane (23) with the central axis (14) of the pivot bearing bores (3a, 4a) and with the respective central axis (18a, 18b) of the locking bores (15, 17) lie. Lever arrangement according to one of Claims 1 until 9 , characterized in that the first lever (3) as a valve-side rocker arm with at least one valve contact section (11) for actuating at least one gas exchange valve of the internal combustion engine and the second lever (4) as a cam-side rocker arm with at least one pick-up element (12) for picking up a cam lifting movement of a camshaft (13) of the internal combustion engine.

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