DE102017114061A1 - Valve train of an internal combustion engine - Google Patents

Abstract

The invention relates to a valve train of an internal combustion engine, with at least one hydraulically switchable drag lever (2) having a primary lever (4) and a pivotally mounted on this secondary lever (6), wherein the primary lever (4) at one end (10) with the Valve stem of at least one gas exchange valve in contact and is supported at the opposite end (14) via a bearing dome (16) on a spherical bearing head at least one support element, wherein at least the secondary lever (6) for tapping a cam associated with a cam with at least one cam contact surface ( 20), wherein the secondary lever (6) via at least one pressure spring (22, 22 ') on the primary lever (4) is supported, wherein the secondary lever (6) by means of at least one hydraulically displaceable coupling element (30) with the primary lever ( 4) can be coupled or decoupled from this, and wherein the hydraulic pressure medium from a em switching pressure space of the support element via a central bore in its bearing head to a in the primary lever (4) arranged and from the bearing dome (16) indirectly or directly limited switching pressure chamber (48) passes, which is bounded by the coupling element (30). To ensure the function of the coupling element (30) is provided that downstream of the bearing dome (16) and in front of the switching pressure chamber (48), a filter element (54) is attached to the primary lever (4).

Description

The invention relates to a valve train of an internal combustion engine, with at least one hydraulically switchable drag lever, which has a primary lever and a pivotally mounted on this secondary lever, wherein the primary lever at one end with the valve stem at least one gas exchange valve in contact and at the opposite end via a bearing dome is supported on a spherical bearing head of at least one support element, wherein at least the secondary lever for tapping an associated cam of a camshaft is provided with at least one cam contact surface, wherein the secondary lever is supported via at least one contact spring on the primary lever, wherein the secondary lever by means of at least one hydraulically displaceable Coupling element with the primary lever can be coupled or decoupled from this, and wherein the hydraulic pressure fluid from a switching pressure chamber of the support element via a central bore in s a bearing head to a arranged in the primary lever and indirectly or directly limited by the bearing dome switching pressure space passes, which is bounded by the coupling element.

In variable valve trains of internal combustion engines, in which at least some of the gas exchange valves, such as intake and exhaust valves are operated via switchable cam followers of the cam of a camshaft required for switching the cam follower oil is usually supplied via the support elements on which the rocker arms supported cylinder head side are. By switching the rocker arm either a Hubabschaltung or a Hubumschaltung the respective gas exchange valves can be done.

In the support elements is usually integrated in each case a device for automatic compensation of any existing valve clearance between the associated cam of the camshaft and the valve stem of the associated gas exchange valve. When installed, each support element is inserted into a largely vertically aligned bearing bore of a cylinder head of the internal combustion engine. At least one supply pressure line of a supply oil gallery opens axially into the respective bearing bore. A stored in the interior of a axially movable in a pot-cylindrical housing guided hollow cylindrical piston pressure chamber communicates via axially inner inlet openings in the cylindrical side walls of the housing and the piston with this cylinder head side reservoir pressure line, so leakage escaping from a trapped between the piston and the housing high-pressure chamber Engine oil from the reservoir pressure chamber can be replaced.

To transfer the depending on the current switching state alternately largely unpressurized or under a high switching pressure, effective as a switching oil engine oil opens a switching pressure line a Schaltölgalerie axially further out into the respective receiving bore. A in the interior of the piston axially outwardly arranged switching pressure chamber is on the one hand via the axially outer inlet openings in the cylindrical side walls of the piston and the housing with this cylinder head side switching pressure line and on the other hand via a central bore in the bearing head of the piston with a arranged in the associated drag lever switching pressure channel in connection , Since the engine oil contained in the reservoir pressure chamber and in the switching pressure chamber of a hydraulic support element fulfills different functions and may have different high pressures, these pressure chambers located within the interior of the piston are usually separated from each other by a bulkhead element. A typical embodiment of such a double-flow hydraulic support element is, for example, from DE 103 30 510 A1 known.

The switchable drag levers each have a frame-shaped primary lever and a pivotally mounted on this secondary lever. The primary lever is in contact at one end with a valve stem of at least one gas exchange valve and is supported at its opposite end by means of a bearing dome on a spherical bearing head of at least one hydraulic support element. The secondary lever is supported for tapping an associated cam of a camshaft via at least one contact pressure spring on the primary lever.

Depending on the switching function of the finger lever, via which either a Hubabschaltung or a Hubumschaltung the associated gas exchange valve can be realized, and the primary lever via two arranged on the side walls and usually designed as sliding surfaces tap elements with associated cam of the camshaft can be in contact.

By means of at least one hydraulically displaceable coupling element, the secondary lever can be coupled against the action of a spring element either with the primary lever or decoupled from this. The engine oil used as switching oil passes through a central bore in the bearing head of the hydraulic support element and arranged in the primary lever between the bearing dome and the coupling element switching oil passage from the switching pressure chamber of the support element in a switching pressure space adjacent to the coupling element.

A hydraulically switchable drag lever, in which the secondary lever can be coupled to the primary lever by the action of a coupling bolt with pressure oil, is exemplary in FIG DE 10 2004 051 422 A1 described. A trained as a coupling pin coupling element is guided axially movable in a longitudinal bore of the primary lever and is held in the pressureless state of a coil spring designed as a compression spring outside a projection of the secondary lever. By supplying pressurized switching oil from the bearing dome and the switching oil passage in an annular switching pressure chamber within the longitudinal bore of the coupling pin is pressed against the action of the compression spring under the projection of the secondary lever, whereby the secondary lever is coupled to the primary lever.

Another hydraulically switchable drag lever, in which the secondary lever can be decoupled by applying a coupling pin with pressure oil from the primary lever, is exemplary in the DE 10 2006 057 894 A1 disclosed. A trained as a coupling pin coupling element is axially movably guided in a stepped longitudinal bore of the primary lever and is held in the pressureless state of a coil spring designed as a compression spring in register with a projection of the secondary lever. By supplying pressurized switching oil from the bearing dome and the switching oil passage in an annular switching pressure chamber within the longitudinal bore of the coupling pin is pushed against the action of the compression spring from the overlap with the projection of the secondary lever, whereby the secondary lever is decoupled from the primary lever.

The switching oil gallery is usually connected to an oil supply system of the internal combustion engine, in which at least one filter element for the separation of harmful particles, such as combustion-related carbon particles as well as processing and wear caused metal particles is arranged. Other filter elements are usually also arranged on the mostly designed as a solenoid valves switching valves, via which the switching oil lines between a largely pressureless state or a low, insufficient for the switching of the cam follower pressure and a high switching pressure can be switched. Nevertheless, damaging particles can enter the support elements and further into the switchable drag levers via the shift oil gallery, which may affect the switching function in the rocker arms. This applies in particular to the initial commissioning of an internal combustion engine after its assembly, in which particles not removed from the mechanical processing of the cylinder head can pass via the switching oil gallery into the hydraulic support elements and from these into the switchable drag levers.

To avoid such disadvantages are from the RU 2 231 650 C2 and the FR 2 910 529 A3 Already single-flow hydraulic support elements for non-switchable valve trains an internal combustion engine with built-in filter elements known there. In the support element according to the RU 2 231 650 C2 a filter element is disposed within the piston between two diagonally opposite in the cylindrical side wall of the piston arranged inlet openings and a check valve. The filter element consists of a dome-like arched filter screen and an annular edge web. It is fixed axially in the piston by means of a fastening element inserted into the inlet openings. The assembly of the filter element within the piston is judged to be relatively expensive. In the support element according to the FR 2 910 529 A3 is designed as a filter ring filter element according to a first arrangement in an outer annular recess and arranged according to a second arrangement on an inner annular shoulder in the cylindrical side wall of the housing of the local hydraulic support element. The annular recess and the annular shoulder are arranged on the cylindrical side wall of the housing such that the annular filter covers the inlet openings of the housing. The ring filter is designed circumferentially closed and consists of a cylindrical filter screen and two annular edge webs, which requires a strong elongation of the ring filter during assembly of the filter element, at least in the first embodiment.

In view of the disadvantages of these known designs and arrangements of filter elements, the invention has the object to provide an alternative arrangement of a filter element to protect the coupling mechanism of a switchable finger lever of the type mentioned, in which the filter element is easier to install and for maintenance and repair work easier to clean or replace.

This object is achieved by a valve train with the features of claim 1. Advantageous developments are defined in the dependent claims.

The invention accordingly relates to a valve train of an internal combustion engine, having at least one hydraulically switchable drag lever, which has a primary lever and a second lever mounted pivotably on the latter, wherein the primary lever is in contact with the valve stem of at least one gas exchange valve at one end and is supported at the opposite end by a bearing dome on a spherical bearing head of at least one support element, at least the secondary lever being provided with at least one cam contact surface for tapping an associated cam of a camshaft, wherein the secondary lever is supported via at least one pressure spring on the primary lever, wherein the secondary lever by means of at least one hydraulically displaceable coupling element with the primary lever can be coupled or decoupled from this, and wherein the hydraulic pressure fluid from a switching pressure chamber of the support element via a central bore in its bearing head arranged in the primary lever and indirectly or directly limited by the bearing dome switching pressure space passes, which is bounded by the coupling element.

In order to prevent the entry of harmful particles in the coupling mechanism of the finger lever is provided that is attached to the primary lever downstream of the bearing dome and in front of the switching pressure chamber, a filter element.

By the filter element harmful particles that have come from the switching oil gallery in the switching pressure chamber of the support element, intercepted and kept away from the coupling mechanism of the drag lever, so that the switching function of the rocker arm, which can be used either Hubabschaltung or Hubumschaltung an associated gas exchange valve, ensured is.

According to a further embodiment it can be provided that in the inner wall of the bearing dome between an annular contact line, on which a contact contact with the bearing head of the support takes place, and the switching pressure chamber, a circular inner groove is formed, and that of a filter screen and the filter screen enclosing annular Edge web existing filter element is inserted by means of the edge web in the inner groove of the bearing dome.

Due to the arrangement and fixation of the filter element in the outside of the contact line with the bearing head of the support element formed annular groove in the inner wall of the bearing dome on the one hand, a simple assembly of the filter element allows and on the other hand with appropriate training excluded contact of the filter element with the bearing head of the support element.

Since an attachment of the filter element by means of an inserted into an annular groove in the inner wall of the bearing dome locking ring space reasons out of the question, the filter element is preferably secured by a latching of the edge web in the inner groove of the bearing dome form-fitting.

The latching of the filter element is preferably formed by a circumferential annular groove in the bottom wall of the inner groove of the bearing dome and an annular groove engaging in this annular groove on the side wall of the edge web of the filter element.

Depending on the elasticity of the material of the edge web, the annular web in the side wall of the edge web may optionally be circumferentially closed or interrupted in sections.

Another embodiment provides that the hydraulic pressure medium passes through a formed in the primary lever switching oil passage of the bearing dome in the limited by the coupling element switching pressure space.

In a further development of this latter variant can also be provided that between the bearing dome and the switching oil channel a funnel-shaped entrance calotte is formed on the primary lever, in which the passed through the filter element hydraulic pressure medium can be calmed.

According to an advantageous embodiment of the drag lever is provided that the filter screen of the filter element is domed in the direction of the entrance dome. The formation of the entrance calotte and the curvature of the filter is made possible, whereby on the one hand increases the effective filter surface and on the other hand, an undesirable contact with the bearing head of the support element is avoided.

With regard to the structure and the manufacture of the filter element can be provided that the filter screen and the edge web of the filter element are made in one piece as an injection molded component of a suitable plastic.

Alternatively, it is also possible that the filter screen of the filter element consists of a wire or fiber braid, and that the filter screen has been encapsulated to form the edge web in an injection molding process with a suitable plastic.

The proposed arrangement of the filter element on the rocker arm can be provided with rocker arms, in which the described coupling mechanism is the support element side or valve side.

• 1 einen sperrelementseitigen Ausschnitt eines hydraulisch schaltbaren Schlepphebels des erfindungsgemäßen Ventiltriebs in einem Längsmittelschnitt,
• 1a einen vergrößerten Ausschnitt A aus 1, und
• 2 den hydraulisch schaltbaren Schlepphebel des erfindungsgemäßen Ventiltriebs gemäß 1 in einer perspektivischen Gesamtansicht.

To further illustrate the invention, the description is accompanied by a drawing with an exemplary embodiments. In this shows

• 1 a blocking element-side section of a hydraulically switchable drag lever of the valve drive according to the invention in a longitudinal center section,
• 1a an enlarged section A out 1 , and
• 2 the hydraulically switchable drag lever of the valve gear according to the invention according to 1 in a perspective overall view.

The invention is described below with reference to the overall view of 2 and the sectional view of 1 the example of a hydraulically switchable rocker arm 2 explained, which is provided for Hubabschaltung an associated gas exchange valve.

The rocker arm 2 has a frame-shaped primary lever 4 and one in this about a rotation axis 8th pivotally mounted secondary lever 6 on. The primary lever 4 indicates at a joint-side first end 10 a U-shaped valve holder 12 for contact with the valve stem of a not shown gas exchange valve. At the opposite second end 14 indicates the primary lever 4 a camp dome 16 on, about the rocker arm 2 is supported in the installed state on the spherical bearing head of a not shown hydraulic support element. For tapping the circumferential geometry of an associated, but not shown cam of a camshaft is the secondary lever 6 with a tapping roller 20 provided, which is rotatably mounted on this. About two trained as torsion springs pressure springs 22 . 22 ' at the second end 14 of the primary lever 4 on both sides arranged cylindrical projections 18 are arranged, are the primary lever 4 and the secondary lever 6 so braced against each other that regardless of the switching state of the finger lever 2 the primary lever 4 with the valve holder 12 on the valve stem of the associated gas exchange valve and with the bearing dome 16 held on the bearing head of the respective support element and the secondary lever 6 with the tapping roller 20 is held in tapping contact with the associated cam of the camshaft.

The coupling mechanism of the finger lever 2 is in the sectional view according to 1 shown, which is designed as a simple stepped coupling pin coupling element 30 having. The coupling pin 30 is axially movable in a double-stepped longitudinal bore 24 in the primary lever 4 guided and has axially inside a flat contact surface 32 on. Through a transverse hole in the longitudinal 24 used, at the contact surface 32 adjoining wire bolts 36 is the coupling pin 30 secured against rotation about its longitudinal axis. Axially outside is the coupling pin 30 with a compression spring designed as a helical spring 38 in contact, axially outward on a spring plate 40 is supported, which in turn via a into an annular groove 28 in the inner wall of the longitudinal bore 24 inserted circlip 42 is supported. The secondary lever 6 has a longitudinal direction of the finger lever 2 outward-facing projection 44 on, which with one with the contact surface 32 of the coupling bolt 30 co-acting flat contact surface 46 is provided.

In the area between an axially inner shoulder 26 the longitudinal bore 24 and a paragraph 34 of the coupling bolt 30 is a function of the axial position of the coupling pin 30 more or less large annular cylindrical pressure chamber 48 into which a switching oil channel 50 empties. The switching oil channel 50 stands above a funnel-shaped entrance calotte 52 with the camp dome 16 in connection, which in turn is connected via a central bore in the bearing head of a hydraulic support element and a switching pressure chamber of the support element with a switching pressure line of a switching oil gallery of the internal combustion engine. Thus passes as a switching oil effective engine oil, which is largely unpressurized depending on the switching state or is under a minimum pressure or is under a high switching pressure, on the bearing dome 16 , the entrance calotte 52 and the switching oil channel 50 in the switching pressure chamber 48 in the longitudinal bore 24 of the primary lever 4 ,

In the case of overpressure or reduced pressure under pressure 48 becomes the coupling pin 30 from the compression spring 38 with his heel 34 against the inner heel 26 the longitudinal bore 24 pressed. In this in 1 illustrated resting position is the coupling pin 30 in overlap with the projection 44 of the secondary lever 6 , in which the secondary lever 6 about the concern of the contact surface 46 his lead 44 at the contact surface 32 of the coupling bolt 30 at the primary lever 4 is supported, causing the secondary lever 6 and the primary lever 4 mechanically coupled together.

By contrast, by switching an associated switching valve in the Schaltölgalerie a high switching pressure in the switching pressure chamber 48 passed, so the coupling pin 30 against the restoring force of the compression spring 38 towards the spring plate 40 shifted and thereby out of engagement with the projection 44 of the secondary lever 6 brought. The secondary lever 6 is characterized by the primary lever 4 decoupled and springs at a load through the associated cam of the camshaft opposite the primary lever 4 a, so that the associated gas exchange valve remains closed.

To protect the coupling mechanism of the finger lever 2 before the entry of harmful particles is one from a filter 56 and an annular edge web enclosing the filter screen 58 existing filter element 54 in the camp dome 16 arranged. As in the in 1a magnified pictured detail A according to 1 is clearly visible, this is in the inner wall 62 the camp dome 16 outside an annular contact line 68 , at which a Berührkontakt takes place with the bearing head of the support element, in the transition between the bearing dome 16 and the entrance calotte 52 a circular inner groove 64 formed, in which the filter element 54 with its edge bridge 58 is used.

The filter screen 56 of the filter element 54 is towards the entrance calotte 52 dome-shaped arched, whereby on the one hand its effective filter surface is increased and on the other hand, an undesirable contact with the bearing head of the support element is avoided. For fastening the filter element 54 is a catch of the edge bar 58 in the inner groove 64 the camp dome 16 intended. The latching is in the present case by a circumferential annular groove 66 in the bottom wall of the inner groove 64 the camp dome 16 as well as through a in the annular groove 66 engaging ring bridge 60 formed, which in the side wall of the edge web 58 of the filter element 54 is trained. Depending on the elasticity of the material of the edge web 58 can the ring bridge 60 either peripherally closed or interrupted in sections.

LIST OF REFERENCE NUMBERS

2

cam follower

4

Primary lever of the rocker arm

6

Secondary lever of the finger lever

8th

axis of rotation

10

First end of the rocker arm

12

Valve intake on the rocker arm

14

Second end of the rocker arm

16

Bearing cam of the rocker arm

18

Projection on the primary lever

20

Cam contact surface, gripping roller with cam contact surface

22, 22 '

Pressure spring, leg spring

24

Longitudinal bore in the primary lever

26

Inner shoulder of the longitudinal bore

28

Ring groove in the longitudinal bore

30

Coupling element, coupling pin

32

Contact surface on the coupling pin

34

Paragraph on the coupling pin

36

wire bolt

38

Compression spring, coil spring

40

spring plate

42

circlip

44

Projection on the secondary lever

46

Contact surface on the projection of the secondary lever

48

Switching pressure chamber

50

Switching oil passage

52

Eintrittskalotte

54

filter element

56

filter screen

58

Edge web of the filter element

60

Ring bar on the edge bar

62

inner wall

64

inner groove

66

ring groove

68

contact line

A

neckline

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 10330510 A1 [0004]
• DE 102004051422 A1 [0008]
• DE 102006057894 A1 [0009]
• RU 2231650 C2 [0011]
• FR 2910529 A3 [0011]

Claims (10)

Valve gear of an internal combustion engine, with at least one hydraulically switchable rocker arm (2) having a primary lever (4) and a pivotally mounted on this secondary lever (6), wherein the primary lever (4) at one end (10) with the valve stem at least one gas exchange valve is in contact and at the opposite end (14) via a bearing dome (16) on a spherical bearing head of at least one support element is supported, wherein at least the secondary lever (6) for tapping a cam associated with a cam cam having at least one cam contact surface (20) is provided , wherein the secondary lever (6) via at least one contact spring (22, 22 ') is supported on the primary lever (4), wherein the secondary lever (6) by means of at least one hydraulically displaceable coupling element (30) with the primary lever (4) coupled or is decoupled from this, and wherein the hydraulic pressure fluid from a switching pressure chamber of Abstü tzelementes via a central bore in its bearing head to a in the primary lever (4) arranged and from the bearing dome (16) indirectly or directly limited switching pressure chamber (48) passes, which is bounded by the coupling element (30), characterized in that downstream of the Bearing cup (16) and in front of the switching pressure chamber (48) has a filter element (54) is attached to the primary lever (4). Valve gear after Claim 1 , characterized in that in the inner wall (62) of the bearing dome (16) between an annular contact line (68), at which a contact contact with the bearing head of the support takes place, and the switching pressure chamber (48) has a circular inner groove (64) is formed, and that a filter element (54) consisting of a filter screen (56) and an annular edge web (58) enclosing the filter screen is inserted into the inner groove (64) of the bearing socket (16) by means of the edge web (58). Valve gear after Claim 2 , characterized in that the filter element (54) by a latching of its edge web (58) in the inner groove (64) of the bearing dome (16) is positively secured. Valve gear after Claim 3 , characterized in that the latching of the filter element (54) by a circumferential annular groove (66) in the bottom wall of the inner groove (64) of the bearing dome (16) and in this annular groove (66) engaging annular web (60) on the side wall of the edge web (58) of the filter element (54) is formed. Valve gear after Claim 4 , characterized in that the annular web (60) on the side wall of the edge web (58) is closed circumferentially or interrupted in sections. Valve gear according to one of the preceding claims, characterized in that the hydraulic pressure medium via a in the primary lever (4) formed switching oil passage (50) of the bearing dome (16) in the coupling element (30) limited switching pressure chamber (48) passes. Valve gear after Claim 6 , characterized in that between the bearing dome (16) and the switching oil channel (50) a funnel-shaped inlet dome (52) are formed on the primary lever (4). Valve gear after Claim 7 , characterized in that the filter screen (56) of the filter element (54) is dome-shaped in the direction of the inlet dome (52). Valve drive according to one of Claims 1 to 8th , characterized in that the filter screen (56) and the edge web (58) of the filter element (54) are made in one piece as an injection molded component made of a plastic material. Valve drive according to one of Claims 1 to 9 , characterized in that the filter screen (56) of the filter element (54) consists of a wire or fiber braid, and that the filter screen (56) has been overmolded in an injection molding process with a plastic to form the edge web (58).

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