DE102007008409A1 - Valve gear of an internal combustion engine with a drag lever - Google Patents

Abstract

Proposed is a valve train (1) of an internal combustion engine (2) with a drag lever (4) which is provided with a roll (9) rolling on a cam (3) and which acts on a gas exchange valve (6), and with a hydraulic medium supply (15) of the internal combustion engine connected support element (5) with a condyle (13) on which the rocker arm with a socket (12) is pivotally mounted, wherein a running through the condyle and within the socket opening inflow opening (18) and in the socket a flow opening (19) communicating with the inlet opening is provided for gating the cam and / or the roller. In this case, the openings in the pivoting direction of the finger lever should be arranged offset from one another such that they are hydraulically separated from each other in the closed position of the gas exchange valve or hydraulically connected to each other only via a throttle gap (20).

Description

Field of the invention

The The invention relates to a valve train of an internal combustion engine with a drag lever with a rolling on a cam Roll is provided and at one end a gas exchange valve between a closed position and an open position hubbeaufschlagt, and with a to a hydraulic fluid supply the internal combustion engine connected support a spherical condyle on which the rocker arm with a dome-shaped socket at the other end pivotally is stored. It is a running through the condyle and within the socket opening inflow opening for hydraulic means and in the socket one with the inflow opening hydraulically communicating flow opening for Provided hydraulic means for gating the cam and / or the roller.

Background of the invention

such Valve drives with end to stationary in the internal combustion engine arranged supporting elements ball-jointed mounted Rocker arms are known in the art and wear due their rolling contact between the cam and the roller one, compared to a sliding contact, considerable reduction the valvetrain friction. For lubrication and / or cooling of the rolling contact, it is common for the socket the toggle lever with a for gating the cam and / or the role of serving flow opening for pressurized To provide hydraulic means. This arrives, starting from the hydraulic fluid supply of Internal combustion engine and a hydraulic medium path connected thereto within the support element, via the inflow opening in the joint contact between condyle and socket and serves at the same time the lubrication of the joint contact.

Such a valve train is for example of the generic type DE 42 34 868 A1 known. In this case, the inflow opening and the flow opening are in permanent hydraulic connection with each other, so that a continuous gating of the roller takes place independently of the stroke position of the gas exchange valve. However, the hydraulic medium also conveyed continuously into the rolling contact between the cam and the roller can lead to unfavorable lubricating film conditions in the rolling contact with regard to the cyclically fluctuating contact forces. While in the opening phase of the gas exchange valve, the load of the rolling contact by the then effective valve spring force and acceleration forces with a reasonable, ie tribologically favorable lubricating film height, it may in the closed phase of the gas exchange valve and the then low load of Wälzkontakts to an impermissibly high accumulation of hydraulic fluid come before the rolling contact and a correspondingly large lubricating film height in the rolling contact. Applicant's research has shown that an excessive supply of hydraulic fluid can significantly increase the likelihood of temporary slip, comparable to the effect of aquaplaning, between the roller and the cam. This temporary slippage carries the risk of premature surface wear on the contact partners, with wear in the form of chatter marks manifested in the tests.

One Another disadvantage of the continuous gating can by a Increase in hydrodynamic valve train friction due to excessive Hydraulic agent entry before and placed in the rolling contact be.

After all can be used alone for the gating Hydraulikmitteistrom especially in multi-valve internal combustion engines to a significant proportion of the total flow of the Add hydraulic fluid pump and, like the hydrodynamic valve train friction, also a considerable contribution to the so-called Reibmitteldruck as a measure of the power loss of the internal combustion engine represent.

Object of the invention

Of the The present invention is therefore based on the object, a valve train of the aforementioned type so that the mentioned disadvantages eliminated with simple means. Accordingly, on the one hand the Gating the cam and / or the roller with hydraulic means so be designed that one on the life requirements of the internal combustion engine coordinated operation of the valve train without premature surface wear Roller or cam is enabled. On the other hand should the power dissipation of the internal combustion engine associated with the gating be as low as possible.

Summary of the invention

According to the invention this object is solved by the features of the characterizing part of claim 1, while advantageous developments and refinements of the invention are the dependent claims. Accordingly, the flow opening and the inlet opening in the pivoting direction of the finger lever should be arranged offset from one another such that the flow opening and the inlet opening in the closed position of the gas exchange valve hydraulically vonein separately or hydraulically connected to each other only via a throttle gap. Consequently, the hydraulic medium flow required for gating open when the gas exchange valve is open at closed sen gas exchange valve or significantly reduced by throttling, so that the entry of hydraulic fluid in or before the then sufficiently loaded rolling contact between cam and roller cyclically intermittent or swelling with open gas exchange valve. The between them with closed gas exchange valve, ie during the base circle phase of the cam, intermittent or throttled gating, however, ensures that there is no excessive entry of hydraulic fluid in the then only slightly loaded rolling contact.

One Another advantage of cyclically suspending or throttling gating is that of the hydraulic pump of the internal combustion engine burdening and participating in Reibemitteldruck the internal combustion engine Hydraulic fluid flow can be reduced by the valve train. For example, in the case of a cam with 240 ° base circle phase and 120 ° valve opening phase at cyclic complete gating a reduction of the for the gating required hydraulic fluid flow by two-thirds of the original Result in continuous gating.

In Further development of the invention, it is provided that the flow opening as a stepped bore with at least two different and in Flow direction increasing cross-sectional areas is trained. Especially with the smallest flow cross sections can be a so designed flow opening economically by producing larger ones Cross-sections of the stepped bore in the case of a cast lever molded or are stamped in the case of a sheet metal lever and the for the flow decisive smallest cross-section by other known methods such as drilling, laser drilling or punching will be produced.

Furthermore If the support element is a known hydraulic Have lash adjuster. It also happens connected to the hydraulic fluid supply of the internal combustion engine Valve play compensation device benefits that the hydraulic medium supply during the valve clearance compensation operation, d. H. during the base circle phase noises, not or only to a limited extent by others Consumer and in this case by the gating of the cam and / or the role is loaded, so in order to have a fast Valve lash compensation always a sufficiently high hydraulic fluid pressure is available. In the alternative case, that it It is a support element with mechanical valve clearance compensation acts, the connection of the support element to the Hydraulic fluid supply of the internal combustion engine only the gating the cam and / or the roller and the lubrication of the joint contact.

Farther It is envisaged that the drag lever with one on the socket extending deflecting element is provided, which from the flow opening escaping hydraulic fluid in the direction of the cam and / or in Direction of the role deflects. On the proviso that one through the flow opening itself formed deflection, such as for example, in the cited document by two intersecting bores is formed, not provided, and due to the offset in the pivoting direction of the finger lever to each other Arrangement of the openings may be such a deflecting element for targeted gating of the cam and / or the role essential be.

there It may be useful in further development of the invention be that the deflecting element is shaped so that the hydraulic fluid in the direction of the cam and spaced from the rolling contact is deflected between the cam and the roller. By this measure can also during the open gas exchange valve an excessive and frustrating Accumulation of hydraulic fluid immediately before the rolling contact prevents and an entry of hydraulic fluid into the rolling contact be limited to a sufficient degree. This is especially true for a so-called pulled valve train, in which the currently engaged cam tip from the support also turns away and for the entry of hydraulic fluid significant arc section between the injection point on the cam and the rolling contact is correspondingly small.

After all It may be provided that the deflection element is part of the drag lever fastened fastener that is the captive holder of the support element on the drag lever and serves as the socket encompassing sheet metal clamp is formed. In this case, the sheet metal clamp a running under the socket first section with a Recess for the support element and an on the socket extending second portion with the integrally formed deflecting element on. An educated as a cost-effective sheet metal clamp Connecting element itself is in a variety of design variants known and can essentially cost neutral to the molded on it Deflecting be extended.

Brief description of the drawings

Further features of the invention will become apparent from the following description and from the drawings, in which an embodiment of the invention is shown. Show it:

1 an overall view of a valve train according to the invention with closed gas exchange valve;

2 the detail A from 1 in an enlarged view;

3 an overall view of the valve train with open gas exchange valve;

4 the detail B off 3 in an enlarged view and

5 the detail B off 3 in a perspective partial sectional view.

Detailed description of drawings

In 1 is an inventive valve train 1 a here only indicated internal combustion engine 2 with a cam 3 a camshaft, a drag lever 4 , a stationary in the internal combustion engine 2 mounted support 5 and a gas exchange valve 6 disclosed. The gas exchange valve 6 is in a known manner by a valve spring, not shown here by means of a spring plate 7 in the closing direction kraftbeaufschlagt and is in accordance with the illustrated base circle phase of the cam 3 in its closed position. The one here from sheet material converted lever body 8th with one on the cam 3 rolling role 9 having rocker arms 4 charged at one end 10 the gas exchange valve 6 and is at the other end 11 with a dome-shaped socket 12 on a spherical condyle 13 the support element 5 pivotally mounted. That with a feed 14 to the hydraulic fluid supply 15 the internal combustion engine 2 connected support element 5 is in a known manner with a hydraulic valve clearance compensation device 16 provided and with the cam follower 4 by means of a fastener attached to this 17 combined to form a mounting unit.

The detail A essential for the understanding of the invention is in 2 shown enlarged. The support element 5 has one with the inlet 14 hydraulically communicating, concentrically through the condyle 13 running and within the socket 12 opening inflow 18 on. One through the joint socket 12 running and for gating the cam 3 serving flow opening 19 is opposite the inflow opening 18 in the pivoting direction of the rocker arm 4 staggered. This offset is such that the inflow opening 18 and the flow opening 19 at the closed gas exchange valve 6 and the currently effective base circle phase of the cam 3 corresponding pivot position of the finger lever 4 only via a throttle gap 20 hydraulically connected to each other. The throttle gap 20 reduces the flow from the opening 19 emerging, not shown here hydraulic fluid flow to a large extent and has a crescent-shaped longitudinal section. This results from the surface geometries of the spherical condyle 13 with a radius 21 and the pan 12 with a so-called Gothic profile, ie with a larger and midpoint offset radius 22 , wherein the throttle gap 20 through joint contact - here through the points 23 symbolizes - limited.

In 3 is the valve train 1 in an open position of the gas exchange valve 6 at currently effective maximum elevation of the cam 3 and the corresponding pivot position of the finger lever 4 shown. As related to the in 4 shown detail B leads the opposite 1 twisted swivel position of the finger lever 4 to a sufficient coverage of inflow 18 and flow opening 19 forming a low-throttle hydraulic fluid jet or spray 23 , here by a deflector 24 only on the cam 3 and sufficiently spaced for rolling contact between the cam 3 and the role 9 is directed.

The design of the self not on the cam 3 directed flow opening 19 was also based on the 4 explained. The flow opening 19 is here as a stepped bore 25 with three different and increasing in the flow direction cross-sectional areas 26 . 27 and 28 educated. The most relevant for the flow smallest cross-sectional area 26 is produced by punching, after the cross-sectional areas following in the direction of flow 27 and 28 have been produced by embossing. Any resulting deformation or burr formation on the inner lateral surface of the socket 12 can be eliminated by re-embossing the inner surface.

The one-piece on the formed as a sheet metal chamber connecting element 17 molded deflecting element 24 goes from the perspective detail view according to 5 out. That, apart from the deflecting element 24 , known per se connecting element 17 has one under the socket 12 extending first section 29 with a recess 30 for the support element 5 and specifically for snapping the condyle 13 , one on the socket 12 extending second section 31 with the here at the end of shaped and arcuate deflecting element 24 as well as the first section 29 with the second Ab cut 31 connecting intermediate section 32 on and surrounds the socket 12 U-shaped. It is obvious that by a manufacturing technology easily produced shape change of the deflecting element 24 a cost-neutral modular design of the valve train 1 with matched Anspritzwinkeln the hydraulic fluid without changing the flow opening 19 in the socket 12 is possible.

1

valve train

2

Internal combustion engine

3

cam

4

cam follower

5

supporting

6

Gas exchange valve

7

spring plate

8th

lever body

9

role

10

The End

11

The End

12

socket

13

joint head

14

Intake

15

Hydraulic medium supply

16

hydraulic Valve lash adjuster

17

connecting element

18

inflow opening

19

Flow opening

20

throttle gap

21

radius of the condyle

22

radius the joint socket

23

joint Contact

24

deflecting

25

stepped bore

26

Cross sectional area

27

Cross sectional area

28

Cross sectional area

29

first Section of the connecting element

30

recess

31

second Section of the connecting element

32

intermediate section of the connecting element

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 4234868 A1 [0003]

Claims (6)

Valve train ( 1 ) an internal combustion engine ( 2 ) with a drag lever ( 4 ), which is connected to a cam ( 3 ) rolling role ( 9 ) and at one end ( 10 ) a gas exchange valve ( 6 ) between a closed position and an open position, and with a to a hydraulic medium supply ( 15 ) of the internal combustion engine ( 2 ) connected supporting element ( 5 ) with a spherical condyle ( 13 ), on which the rocker arm ( 4 ) with a dome-shaped socket ( 12 ) on the other end ( 11 ) is pivotally mounted, one by the condyle ( 13 ) and within the socket ( 12 ) inflow opening ( 18 ) for hydraulic fluid and in the socket ( 12 ) one with the inflow opening ( 18 ) hydraulically communicating flow opening ( 19 ) for hydraulic means for gating the cam ( 3 ) and / or the role ( 9 ), characterized in that the flow opening ( 19 ) and the inflow opening ( 18 ) in the pivoting direction of the rocker arm ( 4 ) are arranged offset to one another such that the flow opening ( 19 ) and the inflow opening ( 18 ) in the closed position of the gas exchange valve ( 6 ) hydraulically separated from each other or only via a throttle gap ( 20 ) are hydraulically connected to each other. Valve train ( 1 ) according to claim 1, characterized in that the flow opening ( 19 ) as a stepped bore ( 25 ) having at least two different and increasing in the flow direction cross-sectional areas ( 26 . 27 ) is trained. Valve train ( 1 ) according to claim 1, characterized in that the supporting element ( 5 ) a hydraulic valve clearance compensation device ( 16 ) having. Valve train ( 1 ) according to claim 1, characterized in that the drag lever ( 4 ) with one on the socket ( 12 ) extending deflecting element ( 24 ) provided by the flow opening ( 19 ) leaking hydraulic means in the direction of the cam ( 3 ) and / or in the direction of the roll ( 9 ) redirects. Valve train ( 1 ) according to claim 4, characterized in that the deflecting element ( 24 ) is shaped so that the hydraulic fluid in the direction of the cam ( 3 ) and spaced from the rolling contact between the cam ( 3 ) and the role ( 9 ) is deflected. Valve train ( 1 ) according to claim 4, characterized in that the deflecting element ( 24 ) Part of a towing lever ( 4 ) fastened connecting element ( 17 ), which for the captive mounting of the support element ( 5 ) on the rocker arm ( 4 ) and as the socket ( 12 ) encompassing sheet metal clamp is formed, which sheet metal clip under the joint socket ( 12 ) first section ( 29 ) with a recess ( 30 ) for the supporting element ( 5 ) and one on the socket ( 12 ) second section ( 31 ) with the deflecting element formed thereon ( 24 ) having.