CN114856746A

CN114856746A - Lever arrangement for a valve train of an internal combustion engine

Info

Publication number: CN114856746A
Application number: CN202210065516.9A
Authority: CN
Inventors: 迪米特里·斯科特; 迈克尔·克诺尔; 安德烈亚斯·穆勒; 哈拉尔德·艾伦德特
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Holding China Co Ltd
Priority date: 2021-01-22
Filing date: 2022-01-20
Publication date: 2022-08-05
Also published as: DE102021101374A1

Abstract

The invention relates to a lever arrangement for a valve train of an internal combustion engine, having at least one first lever (3) and at least one second lever (4), wherein the levers (3, 4) are arranged next to one another on a common pivot axis (2) and are mounted so as to be pivotable and couplable relative to one another for switching, wherein at least one stop (1) is provided in order to limit the pivoting movement of the levers (3, 4), characterized in that the stop (1) is arranged in the region of pivot mounting surfaces (5, 6) of the levers (3, 4).

Description

Lever arrangement for a valve train of an internal combustion engine

Technical Field

The invention relates to a lever arrangement for a valve train of an internal combustion engine.

Background

For example, DE 102006034951 a1 discloses a valve train for an internal combustion engine, which has a switchable rocker structure with a plurality of rockers, which are mounted pivotably on a fixed rocker shaft. A plurality of positioning aids ensure: the rocker for switching is oriented such that an alternating locking or unlocking is possible. The positioning aid arranged on the rocker arm is designed as a stop which is supported on the camshaft.

Disclosure of Invention

The invention is therefore based on the object of simplifying a lever arrangement of the type described above with respect to its construction and manufacture and of designing it at low cost.

The object is achieved by the features of the invention. Further advantageous and claimed embodiments are produced in the respective description and the drawing.

A lever arrangement for a valve train of an internal combustion engine is therefore proposed, which has at least one first lever and at least one second lever, wherein the levers are arranged next to one another on a common pivot axis and are mounted so as to be pivotable and couplable relative to one another for switching. At least one stop is provided to limit the pivotal movement of the lever. In order to keep the component tolerance chain on the stop about the bearing axis as small as possible, the stop is arranged in the region of the pivot bearing surface of the lever. A simply constructed stop can thus be realized, which can be produced with high precision and low cost with a reduced component tolerance chain.

In the basic state of the lever, therefore, precise positioning of the lever and precise and fault-free switching of the lever in a precisely defined end position on the stop are ensured.

In a particularly simple and space-saving manner, the stop can be formed by a projection on the first lever and a recess on the second lever, so that the projection engages in the recess in a pivotably movable manner and can rest in the recess on the second lever.

In a particularly advantageous manner, the projections and recesses can be formed on the pivot bearing surface of the lever.

It is also particularly advantageous if the projection is formed as an extension of the 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 providing the projection, and the pivot bearing surface on the first lever can be enlarged, so that the surface pressure can be reduced. The stop can therefore be arranged at any point on the support diameter and can thus be adapted in particular simply to the installation and operating conditions. At the same time, the component tolerance chain on the stop about the pivot or bearing axis can be optimally reduced. Furthermore, the stop can be integrated into the pivot bearing of the lever in a particularly space-saving and compact manner.

A further simplified embodiment of the invention can be implemented as follows: the projection on the first lever is formed in the form of a ring segment in a protruding manner and forms an extension of the pivot bearing surface on the first lever on the inner diameter. The projection can thus be formed in the manner of a claw on the first lever for engagement on the second lever. Preferably, the projection simultaneously forms a first stop surface on at least one end side oriented in the pivoting direction for abutting against the second lever. It is also possible for limiting the pivoting movement in both pivoting directions to provide stop surfaces on both end sides of the projection, which are each oriented in the pivoting direction.

The recess can be formed in a simple manner as a groove in the pivot bearing surface on the second lever and can form at least one second stop surface on at least one end thereof in at least one pivoting direction for abutting against the projection. It is also conceivable that correspondingly oriented stop faces are provided at both ends of the recess in each case for limiting 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 of the pivot bearing surface formed on the projection and the second lever with the pivot bearing surface are each mounted in a sliding manner on the outer diameter of the pivot bearing shaft. Therefore, on the stop, the component tolerance chain with respect to the bearing axis and thus the manufacturing effort can be minimized and the accuracy can be further increased.

Preferably, the projection is formed integrally with the first lever, so that the extension of the pivot bearing surface formed by the projection is connected seamlessly to the pivot bearing surface.

Furthermore, the recess on the second lever can be arranged in a further advantageous manner in the region of the pivot bearing surface in which a low surface pressure occurs during operation.

Preferably, on the lever, a pivot bearing hole is provided for bearing the lever on the pivot shaft, and a locking hole is provided for constituting a coupling mechanism for coupling the lever. In this case, a further reduction of the component tolerance chain at the stop element can be achieved, which further simplifies and increases the precision of the production, if the stop element is formed on the first lever with at least one first stop surface and on the second lever with at least one second stop surface, respectively, such that the stop surfaces lie in one plane with the central axis of the pivot bearing bore and the corresponding central axis of the locking bore, respectively.

In a further particularly preferred embodiment of the invention, the first lever forms a valve-side rocker arm having 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 having at least one detection element for detecting a cam lift movement of a camshaft of the internal combustion engine. In this way, by providing the protrusion on the pivot bearing surface of the rocker arm on the valve side, it is possible to better absorb the high load generated in the pivot bearing surface of the rocker arm when the valve is operated. At the same time, it is therefore possible to form a recess in the pivot bearing surface of the rocker arm on the cam side, which is subjected to a smaller load during operation. This enables a cost-effective and space-saving stop to be achieved with high precision in a switchable rocker device which can be driven by a camshaft of an internal combustion engine and has at least two rocker arms for a valve train which are mounted pivotably relative to one another on a common pivot shaft, wherein the rocker device has only one pivot shaft.

The lever arrangement can also comprise a plurality of groups which are arranged on a common pivot axis and each have at least one first lever and at least one second lever, wherein the levers of each group are arranged next to one another and are mounted on the pivot axis so as to be pivotable relative to one another.

Drawings

Other claimed features of the invention will be brought out in the following description and drawings which simply illustrate various embodiments of the invention. The figures show:

fig. 1 shows a side view of a lever arrangement for a valve train of an internal combustion engine according to the invention in a first operating state;

fig. 2 shows a side view of the lever arrangement in a second operating state;

FIG. 3 shows a perspective view of the lever arrangement;

FIG. 4 shows a perspective single view of the first lever;

fig. 5 shows a perspective single view of the second lever.

Detailed Description

The lever arrangement according to the invention for a valve train of an internal combustion engine, which is shown by way of example in fig. 1 to 3, has a first lever 3 and a second lever 4, wherein the

levers

3, 4 are arranged next to one another on a common pivot axis 2 and are mounted so as to be pivotable relative to one another. The stop 1 serves to limit the pivoting movement of the

levers

3, 4 in a precisely defined end position on the stop 1 in the basic state, in which the

levers

3, 4 can be coupled for switching. The

levers

3, 4 are each mounted on the outer diameter of the common pivot shaft 2 in a sliding manner via

pivot bearing surfaces

5, 6 of the pivot bearing such that the

levers

3, 4 can pivot relative to one another in the plane of the drawing. The pivot bearing

surfaces

5, 6 are formed on the inner diameter of pivot bearing

bores

3a, 4a on the

levers

3, 4, through which the common pivot shaft 2 passes. Alternatively, the

pivot bearing surfaces

5, 6 can also be part of the rolling bearing of the

levers

3, 4, respectively.

The first lever 3 is designed as a valve-side lever arm which has a valve contact section 11 at the valve-side lever end for actuating at least one not shown gas exchange valve of the internal combustion engine. The second lever 4 serves as a rocker arm on the cam side and is formed with an extraction element 12, here a cam roller, on the cam-side lever end for extracting a cam lift movement from a camshaft 13 of the internal combustion engine. In this way, the lever device forms a switchable rocker device. In fig. 1, the

levers

3, 4 are switched to the decoupled state during the so-called lift-off, wherein the second lever 4 is in the idle lift and cannot transmit the valve lift for operating the valve. In order to return the

levers

3, 4 into a basic state, which is not pivoted relative to one another, during the idle lift, a return spring mechanism, which is not illustrated, can be provided. Fig. 2 shows the

levers

3, 4 in the coupled basic state for transmitting a valve lift for operating the valves.

The stop 1 is arranged in the region 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 (fig. 1, 2, 4 and 5). In this way, a high precision and precise positioning of the

levers

3, 4 in the basic state is achieved at the stop 1 with a reduced component tolerance chain and reduced manufacturing costs with respect to the bearing axis 14, which at the same time forms the central axis of the pivot bearing

bores

3a, 4 a. Thus, operational faults during switching, in particular jamming of the coupling mechanism for coupling the

levers

3, 4, in particular during coupling and also during decoupling of the

levers

3, 4, are reliably avoided. Since the projection 7 engages in the recess 8 in a pivotably movable manner (fig. 1), a space-saving arrangement of the stop element 1 is achieved. In order to limit the pivoting movement, the projection 7 can rest with a first stop surface 9 against a second stop surface 10 in the recess 8 (fig. 2). The projection 7 and the recess 8 are formed on the

pivot bearing surfaces

5, 6 of the

levers

3, 4, respectively (fig. 4 and 5), as a result of which a simple integration of the stop 1 into the pivot bearing of the

levers

3, 4 is achieved.

In this case, according to fig. 4, the projection 7 is formed on an axial extension 7a of the pivot bearing surface 5 on the first lever 3 and is formed integrally therewith. The projections project in a claw-like manner axially at the edge of the pivot bearing surface 5 on the longitudinal side of the first lever 3. The projection 7 has the shape of a ring segment and forms an extension 7a of the pivot bearing surface 5 on the inner diameter. The extension 7a is seamlessly connected to the pivot bearing surface 5, which in turn increases the pivot bearing surface on the first lever 3. On the end side oriented in the first pivoting direction, the projection 7 forms a first stop surface for abutting against the second lever 4. It is possible, but not necessary, to provide a stop face on the other end side of the projection 7 oriented in the second pivoting direction for limiting the pivoting movement in the second pivoting direction. The first lever 3 is mounted on the outer diameter of the pivot shaft 2 in a sliding manner by means of the pivot bearing surface 5 and its extension 7a formed on the inner diameter of the projection 7 (fig. 2 and 3).

The projections 7 engage in a pivotably movable manner at the same height in corresponding recesses 8 on the pivot bearing surface 6 on the second lever 4 by means of extensions 7a of the pivot bearing surface 5 on the first lever 3 (fig. 1). The clearance 8 forms a free space on the second lever 4 to enable the projection 7 engaged with the first lever 3 to pivot with respect to the second lever 4. The projection 7 can in this case rest with the aid of a first stop surface 9 on a second stop surface 10 in the recess 8 for limiting the pivoting movement of the

levers

3, 4 in the basic state (fig. 2).

According to fig. 5 and 1, the recess 8 is arranged on the second lever 4 in correspondence with the projection 7, axially opposite thereto, and starts from an axial edge of the pivot bearing surface 6. The recess is formed as a groove running axially through the lever 4, which groove forms a second stop surface 10 at a first end in the first pivoting direction for the purpose of abutting against the projection 7 in the basic state of the

lever

3, 4.

In the second pivoting direction, the recess 8 extends in the circumferential or pivoting direction to the second end, so that in the decoupled state of the

levers

3, 4, the projection 7 is freely pivotably movable with the first lever 3 during the idle lift. It is possible, but not necessary, to limit the pivoting movement in the second pivoting direction by a stop face on the second end of the recess 8.

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

During the idle lift, in the decoupled state shown in fig. 1, the

levers

3, 4 can pivot relative to one another in the plane of the drawing. In the uncoupled state of the

levers

3, 4, the projection 7 can pivot with the first lever 3 in the recess 8 until the basic state of the

levers

3, 4 in the cam base circle phase (nockingrundkreiphase) is reached in the pivoting direction, as shown in fig. 2, and the projection 7 with the first stop surface 9 reaches the end of the recess 8 in order to rest against the second stop surface 10.

In order to couple the levers in the final position defined at the stop 1 in the basic state of the

levers

3, 4, the first locking hole 15 on the first lever 3 and the second locking hole 17 on the second lever 4 are aligned with one another (fig. 2, 4 and 5). In the cam base circle phase (fig. 2), the coupling element 16, which is arranged displaceably in the second locking bore 17 and has a coupling-side end, can thus be displaced over a slight axial air gap into the opposing first locking bore 15 on the first lever 3. In this case, the

levers

3, 4 are coupled and in the illustrated cam lift phase the cam lift movement, which is obtained from the camshaft 13 on the second lever 4, can be transmitted on the first lever 3 to at least one gas exchange valve (fig. 2). In order to decouple the

levers

3, 4 in the basic state, the coupling element 16 with the coupling-side end can be displaced back out of the first locking hole 15 into the second locking hole 17 again in the cam base circle phase. The locking holes 15, 17 are each formed as a through-hole in the

levers

3, 4 in the vicinity of the

pivot bearing holes

3a, 4a and extend parallel to the bearing axis 14 or to the center axis of the

pivot bearing holes

3a, 4 a. The coupling element 16, in this case a cylindrical coupling bolt, and the locking bores 15, 17 are parts of a coupling mechanism, not shown in detail, which can be switched by an actuator system, not shown, preferably by an electric actuator. The operation for coupling or uncoupling can also be combined with a prestressed spring mechanism. By means of the described coupling mechanism, a so-called transverse locking of the

levers

3, 4, i.e. transverse locking transverse to the longitudinal axes of the levers, can be achieved. The high accuracy of the stop 1 also makes it possible to implement a coupling mechanism, in particular the locking bores 15, 17, with low component tolerances, as a result of which, in particular, the forces acting on the coupling element 16 can be optimized and wear during operation can be minimized.

The arrangement of the stop 1 is possible in principle at any position on the circumference or on the diameter of the

pivot bearing surfaces

5, 6. Fig. 2 shows two further alternative installation possibilities for the stop 1, wherein the tolerance accuracy of the stop 1 is further increased. Alternative setting possibilities of the stops 1', 1 ″ are each indicated by dashed lines. In both alternatives, the flat stop faces 9 ', 10 ' or 9 ", 10" provided at the final position of the

levers

3, 4 defined at the stops 1 ', 1 "lie in the plane indicated by the dashed lines with the bearing or central axis 14, 18 of the

pivot bearing holes

3a, 4a and the central axis 18 of the locking holes 15, 17, respectively (fig. 1, 2, 4 and 5). In the basic state, alternative positioning of the stop 1 ', 1 ″ in the clockwise direction on the circumference or on the diameter of the

pivot bearing surfaces

5, 6 in the first variant toward the 3 o ' clock direction and in the second variant toward the 9 o ' clock direction is possible (fig. 2).

The pivot shaft 2 is fixed to a carrier part 20 via a screw connection 21 by means of a shaft section 19 which projects at the first lever 3 (fig. 3). An actuator system for switching the coupling mechanism is at least partially accommodated in the housing section 22 of the carrier 20. It is also conceivable for parts of the coupling mechanism to be accommodated there. In this way, the

levers

3, 4, the pivot shaft 2, the coupling mechanism and the actuator system together with the carrier 20 form a preassembled switchable rocker unit which can be fastened in a simple manner to the internal combustion engine, in particular to the cylinder head or other stationary components, by means of the screw connection 21 via the carrier 20.

List of reference numerals

1 stop element

1' stop piece

1' stop

2 pivoting axis

3 lever

3a pivot bearing hole

4 lever

4a pivot bearing hole

5 pivoting bearing surface

6 pivoting bearing surface

7 projection

7a extension

8 keep the empty part

9 stop surface

9' stop surface

10 stop surface

10' stop surface

10 "stop surface

11 valve contact section

12 acquisition element

13 camshaft

14 bearing axis, central axis

15 locking hole

16 coupling element

17 locking hole

18 central axis

19 shaft section

20 load bearing member

21 spiral connecting piece

22 casing section

23 plane of

Claims

1. A lever arrangement for a valve train of an internal combustion engine, having at least one first lever (3) and at least one second lever (4), wherein the levers (3, 4) are arranged next to one another on a common pivot shaft (2) and are pivotably mounted and couplable relative to one another for switching, wherein at least one stop (1) is provided in order to limit the pivoting movement of the levers (3, 4), characterized in that the stop (1) is arranged in the region of pivot mounting surfaces (5, 6) of the levers (3, 4).

2. Lever device according to 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) is pivotably movably engaged into the recess (8) and can rest in the recess (8) on the second lever (4).

3. A lever device according to claim 2, wherein the projection (7) is formed in the extension (7a) of the pivot bearing surface (5) on the first lever (3) and the recess (8) is formed in the pivot bearing surface (6) on the second lever (4).

4. The lever arrangement according to claim 2 or 3, characterized in that the projection (7) on the first lever (3) is designed to project in the form of a ring segment and is formed on the inner diameter on an extension (7a) of the pivot bearing surface (5) on the first lever (3) and on at least one end side oriented in the pivoting direction on at least one first stop surface (9, 9', 9 ") for resting in the recess (8).

5. A lever arrangement according to any one of claims 2 to 4, characterised in that the recess (8) is configured as a groove in the pivot bearing surface (6) of the second lever (4) and forms at least one second stop surface (10, 10', 10 ") on at least one end thereof in at least one pivoting direction for abutting against the projection (7).

6. A lever device according to any one of claims 3 to 5, characterized in that the first lever (3) is slidably supported on the outer diameter of the pivot shaft (2) with the pivot bearing surface (5) and an extension (7a) of the pivot bearing surface formed on the protrusion, and the second lever (4) is slidably supported on the outer diameter of the pivot shaft with the pivot bearing surface (6).

7. A lever device according to any one of claims 3 to 6, characterized in that the projection (7) is constructed in one piece with the first lever (3) such that an extension (7a) of the pivot bearing surface (5) formed on the projection (7) is seamlessly connected to the pivot bearing surface.

8. A lever arrangement according to any one of claims 2 to 7, characterised in that the recess (8) is arranged in a region of the pivot bearing surface (6) of the second lever (4) in which a lower surface pressure occurs during operation.

9. Lever device according to one of claims 1 to 8, characterized in that on the lever (3, 4) a pivot bearing hole (3a, 4a) is provided for bearing the lever on the pivot shaft (2), and provided with locking holes (3a, 4a) for forming 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 ' ) on the second lever (4), so that the stop faces (9 ', 9 ', 10 ') lie in a plane (23) with the central axis (14) of the pivot bearing bore (3a, 4a) and the corresponding central axis (18a, 18b) of the locking bore (15, 17), respectively.

10. Lever arrangement according to one of claims 1 to 9, characterized in that the first lever (3) is designed as a valve-side rocker arm with at least one valve contact section (11) for operating at least one gas exchange valve of the internal combustion engine, while the second lever (4) is designed 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.