CN114810264A

CN114810264A - Structural unit of a switchable valve mechanism for a heavy-duty internal combustion engine

Info

Publication number: CN114810264A
Application number: CN202111549421.6A
Authority: CN
Inventors: 迪米纯·舒特; 哈拉德·艾雷特; 麦克·科尔; 安德里亚斯·默勒
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Holding China Co Ltd
Priority date: 2021-01-21
Filing date: 2021-12-17
Publication date: 2022-07-29
Also published as: DE102021101222A1

Abstract

A cylinder-specific structural unit for a switchable valve train of a heavy-duty internal combustion engine is proposed, which has a shaft part and at least one rocker arm group thereon, which comprises a valve rocker arm and at least one cam rocker arm immediately adjacent thereto, wherein the at least one cam rocker arm has a cam running surface at a longitudinal end of the rocker arm group and the valve rocker arm has an at least indirectly contacting valve contact surface at the other longitudinal end of the rocker arm group, wherein the valve rocker arm bears against the cam rocker arm wall-to-wall in a partial region, in which a coupling element is provided for the selective coupling thereof, and wherein a bearing of the rocker arm group on the shaft part acts as a hydrostatic plain bearing which is implemented only in the section of the shaft bore of the valve rocker arm.

Description

Structural unit of a switchable valve mechanism for a heavy-duty internal combustion engine

Technical Field

The invention relates to a cylinder-specific structural unit for a switchable valve train of a heavy-duty internal combustion engine, having a shaft part and at least one rocker arm group thereon, comprising a valve rocker arm and at least one cam rocker arm next to it, wherein the at least one cam rocker arm has a cam rolling surface at a longitudinal end of the rocker arm group and the valve rocker arm has an at least indirectly contacting valve contact surface at the other longitudinal end of the rocker arm group, wherein the valve rocker arm bears with the cam rocker arm wall-to-wall in a partial region, in which a coupling piece that can be optionally coupled is provided, and wherein the bearing part of the rocker arm group on the shaft part is designed as a hydrostatic plain bearing.

Background

DE 102020113222.0, which has not been published at the time of filing, is the closest prior art. The carrier module for a valve train of a heavy-duty internal combustion engine mentioned therein has two components. A first component on the inlet side, which has exactly one rocker cam arm extending partially wall-to-wall with the rocker valve arm, and a second component on the outlet side, which has two rocker cam arms surrounding the rocker valve arm (see fig. 1). Each rocker arm extends in a separate hydrostatic plain bearing on the entire shaft element (see fig. 8, oil supply to the plain bearing is not shown).

Disclosure of Invention

The object of the invention is to provide a preassembled structural unit whose hydrostatic plain bearing is capable of withstanding high loads.

According to the invention, this object is achieved by the hydrostatic plain bearing being implemented only in a section of the shaft bore of the valve rocker. In this case, according to a particularly preferred development, the shaft bore of the valve rocker is extended on one side of the camshaft by a pipe fitting projecting from the respective outer wall of the camshaft in order to form a hydrostatic plain bearing, the camshaft being supported by its shaft bore on the outer side of the pipe fitting and the inner side of the pipe fitting having the extended shaft bore.

The invention is therefore based on the fact that, in the decoupled state, ultimately only the force of the cam return spring (lost motion spring) and its own mass acceleration act on the one or more rocker cams. Therefore, the cam rocker arm is subjected to only a weak load. In the coupled state, the hydrostatic bearing of the associated rocker arm set is involved, in which case the load of the rocker arm set is essentially the relatively high valve spring force acting first on the valve rocker.

There are plain bearings, the oil film of which is formed and carried only in the section of the widened shaft bore of the valve rocker arm being free of separating play in the high-load state (coupling). The plain bearing is therefore subjected to high hertzian pressures. The loss of lubricating oil is minimal. In the decoupled state of the two rocker arms of the respective rocker arm group, the respective cam rocker arm now performs a pivoting movement via its shaft bore on the outer side of the pipe fitting of the valve rocker arm. Due to the aforementioned weak loads, only low demands are made on the lubrication of the plain bearing.

The structural unit also has the advantage that the lower assembly, which consists only of the rocker arm sets (without shafts) engaging one another, can also be provided separately or operated. In addition, the structural unit is provided integrally with the shaft element on the internal combustion engine. If appropriate, the coupling element can also be a component of the structural unit, as in the case of an electric actuator with a piston slide and a cam return spring, which extends parallel to the shaft part.

The rocker arm can be embodied as a solid component and produced in an MIM method, for example by forging, casting or the like. It is also clear here that a wear-reducing layer, for example a hard material layer (DLC, etc.), can also be applied in the region of the respective sliding bearing.

According to a further development of the invention, the pipe attachment of the respective valve rocker arm should protrude in one piece from the respective outer wall of the valve rocker arm. Alternatively, a separate sleeve may be engaged with the "bottom hole" of the rocker arm in order to widen the sliding bearing.

In a further embodiment of the invention, the shaft part can project onto the respective rocker arm group and can be connected with the region of the structural unit to the cylinder head of the heavy-duty internal combustion engine, for example by a screw connection or a pin connection. The feed of hydraulic medium to the longitudinal bore in the shaft element can also be ensured simultaneously via a screw connection, while at least one transverse bore of each valve rocker arm branches off from the longitudinal bore in the direction of the plain bearing. Alternatively, the hydraulic agent can also be introduced into the shaft element via at least one outer end face of the shaft element.

A support plate, not described in detail, in which for example the aforementioned electric actuator can be accommodated, can also be connected at the same time.

The structural unit can be used on the inlet valve side or on the outlet valve side. The respective other valve side is then embodied as "standard variant" and is therefore not switchable. It is advisable to provide a variability for each valve side, however, wherein an engine brake can also be provided on the outlet side, optionally also in pairs with the switching or switching off of the valve stroke.

Other dependent claims relate to suitable axial fastening of the rocker arm assembly on the shaft and of the cam rocker arm on the pipe attachment of the valve rocker arm. Simple snap ring-groove fastenings are conceivable here, for example. Cotter pins or subsequently applied material transfers, such as packings or the like, are also conceivable.

Drawings

Fig. 1 shows a perspective view of a structural unit of a swing arm group with an inlet side and an outlet side;

FIG. 2 shows a sectional view of the shaft element through the structural unit in the longitudinal direction and

fig. 3 shows a perspective view of the valve rocker (intake side).

Detailed Description

Fig. 1 and 2 show a mechanical unit 1 of a switchable valve train for a heavy-duty internal combustion engine. Each cylinder of a heavy internal combustion engine is provided with a structural unit 1.

The central shaft part 2 can be seen, which has an inlet-side rocker arm set 3a drawn on the left and an outlet-side rocker arm set 3b drawn on the right. The rocker arm set 3a comprises a valve rocker arm 4 against which a cam rocker arm 6 bears directly. The rocker arm group 3b is formed by two

cam rocker arms

7, 8 which surround the valve rocker arm 5.

The

cam rockers

6, 7, 8 each have a

cam running surface

10, 11, 12 in the form of a roller at a longitudinal end 9 of the

rocker arm group

3a, 3 b. The

valve rocker arms

4, 5 each have an indirectly contacting

valve contact surface

14, 15 at the other longitudinal end 13 of the rocker arm set 3a, 3 b. The valve contact surfaces are used for bridge-based actuation for simultaneous actuation of two identically acting gas exchange valves.

As can be seen clearly in fig. 1, the inlet-side rocker valve arm 4 comes into contact with its rocker cam arm 5 wall-to-wall in the partial region 16 a. At the same time, the outlet-side valve rocker arm 5 bears with its

cam rocker arms

7, 8 wall-to-wall on the

partial regions

16b, 16 c. A coupling element, not described in detail, which can be actuated electromagnetically or hydraulically in at least one direction, one of which is shown in fig. 1 and is designated by the reference numeral 17, is provided just in this

partial region

16a, 16b, 16c in order to be coupled selectively.

As can be seen from fig. 2, the two

rocker arm assemblies

3a, 3b extend on a common shaft 2, which has an exposed central projection 33. The point of this embodiment is that the bearing points of the

rocker arm groups

3a, 3b on the shaft element 2 are hydrostatic

plain bearings

18a, 18b, which are implemented only in the section of the significantly widened

shaft bores

19, 20 of the

valve rocker arms

4, 5.

In order to realize the hydrostatic plain bearing 18a of the rocker arm 4 of the inlet-side rocker arm group 3a, the shaft bore 19 of the rocker arm 4 is extended on the side of the rocker arm 6 thereof by a pipe attachment 24 projecting in one piece from the outer wall 21 thereof. The rocker cam 6 extends via its shaft bore 30 on the outer lateral surface 27 of the pipe fitting 24 in a relatively rotatable manner (in the decoupled state).

In order to show the hydrostatic plain bearing 18b of the valve rocker 5 of the outlet-valve-side rocker arm group 3b, the shaft bore 20 of the valve rocker 5 has a

pipe stub

25, 26 projecting in one piece from each

outer wall

22, 23, the

respective cam rocker

7, 8 being supported via its shaft bore 31, 32 on a respective outer lateral surface 28, 29 of the

pipe stub

25, 26 and being able to be moved in a relative rotational manner in the decoupled state.

The hydrostatic plain bearings are therefore free of separating gaps on each rocker arm set 3a, 3b and are exposed to particularly high hertzian pressures. In other words, the bearing width can also be reduced under the same load, which contributes to saving installation space and mass.

The boss 33 of the shaft 2 between the sets of

swing arms

3a, 3b has a plurality of helical holes 34 extending radially therethrough. The shaft element 2 can be screwed fixedly with a cylinder head of a heavy-duty internal combustion engine via a screw bore. In the same way, as shown in fig. 1, the support disks 39 can additionally be connected and arranged together.

The hydraulic medium can be introduced via a corresponding screw hole 34 into a longitudinal bore 35 of the shaft element 2 intersecting the screw hole, which longitudinal bore 35 can be seen in fluid connection with a plurality of transverse bores 36 in the shaft element 2, which lead to the

slide bearings

18a, 18 b.

The

rocker arm sets

3a, 3b are fastened to the shaft element 2 with respect to the outside via a snap ring-groove connection 37. The same is true of the fastening of the

rocker cams

6, 7, 8 to their

pipe attachments

24, 25, 26 via snap ring groove connections 38.

The details of the valve rocker arm 4 can be seen in fig. 3. A pipe fitting 24 is visible on one side and projecting in one piece, on which the rocker cam 6 of the rocker arm set 3a can be supported. It is also possible to see the arm of the cam return spring 40, not described in detail, which in its construction is integrated with the counter surface of the rocker cam 6.

List of reference numerals

1 structural Unit

2 axle part

3a rocker arm group

3b rocker arm group

4-valve rocker arm

5-valve rocker arm

6 cam rocker

7 cam rocker

8 cam rocker arm

9 longitudinal ends

10 cam rolling surface

11 cam rolling surface

12 cam rolling surface

13 another longitudinal end portion

14 valve contact surface

15 valve contact surface

16a partial region

16b partial region

16c partial region

17 coupling element

18a sliding bearing

18b plain bearing

19 axle hole

20 axle hole

21 outer wall

22 outer wall

23 outer wall

24-pipe fitting

25 pipe fittings

26 pipe fittings

27 lateral surface

28 outer side

29 lateral surface

30 shaft hole

31 axle hole

32 axle hole

33 boss

34 spiral hole

35 longitudinal bore

36 transverse hole

37 clasp-groove-connector

38 clasp-groove-connector

39 support plate

40 cam return spring.

Claims

1. A cylinder-specific structural unit (1) for a switchable valve train of a heavy-duty internal combustion engine, having a shaft (2) and at least one rocker arm group (3a, 3b) on the shaft, which comprises a valve rocker arm (4, 5) and at least one cam rocker arm (6, 7, 8) which is located in the immediate vicinity of the valve rocker arm, wherein the at least one cam rocker arm (6, 7, 8) has a cam rolling surface (10, 11, 12) at a longitudinal end (9) of the rocker arm group (3a, 3b) and the valve rocker arm (4, 5) has an at least indirectly contacting valve contact surface (14, 15) at the other longitudinal end (13) of the rocker arm group (3a, 3b), wherein the valve rocker arm (4, 5) and the cam rocker arm (6, 7, 8) are in a partial region (16a, b), 16b, 16c) are in contact with one another wall-to-wall, wherein an optionally couplable coupling element (17) is provided in the sub-region (16a, 16b, 16c), and wherein the bearing of the rocker arm group (3a, 3b) on the shaft element (2) is designed as a hydrostatic plain bearing (18a, 18b) which is implemented only in the region of the shaft opening (19, 20) of the rocker valve (4, 5), wherein the shaft opening (19, 20) of the rocker valve (4, 5) is extended on one side of the rocker cam (6, 7, 8) by a pipe attachment (24, 25, 26) projecting from the respective outer wall (21, 22, 23) of the rocker cam in order to form the hydrostatic plain bearing (18a, 18b), wherein the rocker cam (6, 7, 8) bears via its shaft opening (30, 31, 32) on the outer side (27, 27) of the pipe attachment, 28. 29) and the inner side of the pipe attachment has an elongated axial bore (19, 20).

2. Structural unit according to claim 1, wherein the pipe attachments (24, 25, 26) of the valve rocker (4, 5) either protrude integrally from the valve rocker (4, 5) or as sleeves which engage the valve rocker (4, 5) separately.

3. The structural unit as claimed in claim 1, wherein the shaft element (2) projects from the rocker arm group (3a, 3b) via a boss (33), at least one screw opening (34) extending radially or hexagonally through the boss (33) for engaging the structural unit (1) with a cylinder head of a heavy internal combustion engine, through which screw opening (34) hydraulic medium can simultaneously be introduced into a longitudinal bore (35) of the shaft element (2) intersecting the shaft element, while the longitudinal bore (35) is in fluid connection with at least one transverse bore (36) in the shaft element (2) which leads to a plain bearing (18a, 18b) of the rocker valve arm (4, 5).

4. A structural unit according to claim 3, wherein two sets of rocker arms (3a, 3b) extend over the shaft (2), and wherein a boss (33) connecting the shafts (2) of the two sets of rocker arms (3a, 3b) is located between the two sets of rocker arms.

5. A construction unit according to claim 1, wherein the set of booms (3a, 3b) is fastened to the shaft element (2) in at least one axial direction by means of a flange, such as a snap ring-and-groove connection (37).

6. Structural unit according to claim 1, wherein the at least one rocker cam arm (6, 7, 8) is fastened to a pipe attachment (24, 25, 26) of the rocker valve arm (4, 5) by means of a flange, such as a snap ring-groove connection (38), and can be detached from the pipe attachment (24, 25, 26) of the rocker valve arm (4, 5).