DE102019204831A1 - Valve drive for an internal combustion engine and cylinder head for an internal combustion engine - Google Patents

Abstract

Valve drive (V) for an internal combustion engine, comprising a basic camshaft (1), at least one sliding cam (2) with a first cam group (21) and a second cam group (22) which are axially displaceably received on the basic camshaft (1), and a bearing device (3) for the sliding cam (2), comprising a bearing cover (31), a bearing shell (32) and a bearing seat (33) on the sliding cam (2), the bearing seat (33) between the first cam group (21) and the second cam group (22) is arranged, wherein the bearing seat (33) comprises an annular recess (331, 332) in at least one, preferably in both cam groups (21, 22), and cylinder head (Z) of an internal combustion engine, comprising a valve train, characterized by a valve drive (V) according to at least one of the preceding claims.

Description

The present invention relates to a valve drive for an internal combustion engine according to the preamble of claim 1 and a cylinder head for an internal combustion engine according to the preamble of claim 7.

A cylinder head of an internal combustion engine is, as a rule, equipped with a valve train, in addition to other components such as valves.

A valve drive for an internal combustion engine essentially comprises a base camshaft and at least one slide cam mounted axially displaceably on the base camshaft. Furthermore, the valve drive comprises at least one bearing device in which the sliding cam is rotatably mounted. The bearing device is usually directly connected to the cylinder head or an associated cylinder head cover of the internal combustion engine. The storage device essentially comprises a bearing cover and a bearing shell.

A valve drive for an internal combustion engine is, for example, from DE 10 2007 022 145 A1 and DE 10 2012 016 674 A1 known.

A sliding cam usually comprises a shift gate and at least one group of cams. The cam group includes at least two cams, each with a different cam geometry.

The control times of gas exchange valves can be changed during operation of the internal combustion engine via the sliding cams or the different cam geometries of the cam group. The adjustment of the valve opening times enables an increase in the efficiency of the internal combustion engine, depending on the respective load behavior. This increase can come into play as a gain in power and torque and as a fuel saving.

A cam group usually comprises two cams. However, there is a need for cam groups with more than two cams, in particular three cams. Given a given installation space for the valve train, this poses a challenge with regard to the mounting of the sliding cams; in particular, very narrow bearings result with existing valve spacings.

This is where the present invention comes into play and sets itself the task of providing an improved valve train, in particular to propose a valve train with which an improved or at least equivalent mounting of the at least one sliding cam can be achieved with an increase in the cams per cam group.

According to the invention, this object is achieved by a valve drive with the characterizing features of claim 1. Because the bearing seat comprises an annular recess in at least one, preferably in both, cam groups, the bearing seat can be enlarged, in particular lengthened in the axial direction, without having to change the distance between the cam groups as such. The bearing shell or projections of the bearing shells can to a certain extent be retracted into the respective cam group.

Further advantageous configurations of the proposed invention emerge in particular from the features of the subclaims. The objects or features of the various claims can in principle be combined with one another as desired.

In an advantageous embodiment of the present invention, it can be provided that the recess extends in the axial direction of the sliding cam. The recess could also be addressed as an undercut in the sliding cam. The recess can be produced in a simple manner by machining processes, for example turning or milling.

In a further advantageous embodiment of the present invention it can be provided that the bearing shell has at least one protrusion, preferably a protrusion on both sides, with respect to the bearing cover. The protrusion can be produced in a simple manner in that the bearing shell is made wider than the bearing cover.

In a further advantageous embodiment of the present invention, it can be provided that the bearing cover and the bearing shell are positively connected to one another. This can be implemented, for example, in that a positive connection acting in the axial direction is arranged between the bearing cover and the bearing shell, in particular in the form of a tongue and groove.

In a further advantageous embodiment of the present invention it can be provided that the cam group has at least two cams, preferably three cams, with different cam geometries. In principle, the invention can of course also be used for improved mounting of a two-stage cam group. However, the invention unfolds its potential in particular in three-stage and multi-stage cam systems.

In a further advantageous embodiment of the present invention it can be provided that the recess has a shape corresponding to the protrusion, in particular a rectangular or wedge-shaped shape. The rectangular shape is accordingly easy to manufacture, while the wedge-shaped shape can, if necessary, facilitate the immersion of the protrusion into the recess. The wedge-shaped design means that significantly less material has to be removed from the cam. Since the cam is usually hardened in the area of its running surface and this hardness extends into the material, less material, which has a high hardness, has to be removed from the cam. If the cam is to be produced by forming, the wedge-shaped recess leaves as much material as possible in the area of the hardening zone in order to produce a uniform hardening structure. Furthermore, the wedge shape can simplify the assembly of the cam on the carrier tube if the sliding cam is a built-in cam.

Another object of the present invention is to propose an improved cylinder head for an internal combustion engine, in particular a cylinder head in which an improved or at least equivalent mounting of the at least one sliding cam can be achieved with an increase in the cams per cam group.

According to the invention, this is achieved in that a valve drive according to the invention is installed in the cylinder head.

Further advantageous configurations of the proposed invention emerge in particular from the features of the subclaims. The objects or features of the various claims can in principle be combined with one another as desired.

In an advantageous embodiment of the present invention, it can be provided that the bearing cover is connected to the cylinder head or is partially formed from the cylinder head.

• 1 ein Ausschnitt eines erfindungsgemäßen Zylinderkopfs mit erfindungsgemäßem Ventiltrieb für eine Brennkraftmaschine in einer perspektivischen Schnittdarstellung (der Übersichtlichkeit halber sind die Schiebenocken ohne Nocken dargestellt);
• 1a eine teilweise geschnittene Darstellung eines erfindungsgemäßen Zylinderkopfs mit erfindungsgemäßem Ventiltrieb für eine Brennkraftmaschine (Ausschnitt und nur mit zwei Nocken pro Nockengruppe);
• 2a-c ein Schiebenocken in einer geschnittenen Darstellung (erste bis dritte Position);
• 3a-c ein Schiebenocken in einer geschnittenen Darstellung (erste bis dritte Position).

Further features and advantages of the present invention will become clear on the basis of the following description of preferred exemplary embodiments with reference to the accompanying figures. Show in it

• 1 a section of a cylinder head according to the invention with a valve drive according to the invention for an internal combustion engine in a perspective sectional view (for the sake of clarity, the sliding cams are shown without cams);
• 1a a partially sectioned illustration of a cylinder head according to the invention with a valve drive according to the invention for an internal combustion engine (detail and only with two cams per cam group);
• 2a-c a sliding cam in a sectional view (first to third position);
• 3a-c a sliding cam in a sectional view (first to third position).

First will be on 1 Referenced.

A cylinder head according to the invention Z for an internal combustion engine is equipped with a valve train according to the invention.

A valve drive according to the invention for an internal combustion engine essentially comprises a basic camshaft 1 , at least one sliding cam 2 and at least one storage facility 3 for the sliding cam 2 .

The basic camshaft 1 is designed essentially as a hollow shaft or solid shaft.

The sliding cam 2 essentially comprises a shift gate 23 and at least two groups of cams 21st , 22nd . The cam group 21st or. 22nd comprises at least two cams, preferably three cams N1 , N2 , N3 , each with a different cam geometry. The different cam geometry can also be achieved by different phase positions of the cams N1 , N2 and N3 be generated. The sliding cam 2 is designed as a hollow cylinder and can be moved on the base camshaft 1 recorded. Preferably the sliding cam is 2 non-rotatably on the basic camshaft 1 arranged. The sliding cam 2 can be designed in one piece, but also in several parts. In the example sketched here is the shift gate 23 designed as a separate part, which is inseparable from the cam groups 21st , 22nd connected is. The shift gate 23 can via an actuator 4th be operated.

The storage facility 3 includes a bearing cap 31 , a bearing shell 32 and a bearing seat 33 on the sliding cam. The bearing cap 31 is with a cylinder head Z connected or partially formed from the cylinder head. The bearing shell 32 forms together with the bearing seat 33 a plain bearing. Preferably the bearing shell 32 made of a plain bearing material with advantageous plain bearing properties, such as copper or a copper alloy.

The bearing seat 33 is between two cam groups, in particular between the first cam group 21st and the second group of cams 22nd , arranged.

The other components of a cylinder head or valve drive, such as, for example, retractable or retractable pins for the shift gate, valves, etc., are sufficiently known to those skilled in the art.

According to the invention it is provided that the bearing seat 33 over the clear area between the cam groups 21st , 22nd is extended. In concrete terms, a first annular recess is preferably in each case 331 in the first cam group 21st and a second annular recess 332 in the second group of cams 22nd intended. The entire bearing seat results from the area between the cam groups 21st , 22nd and the recesses 331 , 332 in the cam groups 21st , 22nd . This opens up the possibility that the bearing shell 32 with protrusions 321 , 322 can be equipped in the respective recess 331 or. 332 can immerse and thus increase the plain bearing width while maintaining the cam group spacing and thus the valve spacing. In particular, there is a first overhang 321 provided which of the first recess 331 is facing or can dip into it, as well as a second protrusion 332 which faces the second recess or can dip into it.

It can be seen from this example that an advantageous mounting of the sliding cam can also be implemented, for example, with three-stage sliding cam systems. It can also be seen that the protrusions 321 , 322 preferably by a larger axial expansion of the bearing shell 32 opposite the bearing cap 31 is executed.

The 2a to 2c show the sliding cam 2 in the three proposed positions. For each position it is envisaged that the cams N1 , N2 or N3 are responsible for the valve train. 2a to 2c each show embodiments in which the recess 331 , 332 one to the supernatant 321 , 322 Has a corresponding rectangular shape.

3a to 3c each show embodiments in which the recess 331 , 332 one to the supernatant 321 , 322 has a corresponding wedge-shaped shape.

It should be noted that the recesses or protrusions are shown greatly exaggerated in the figures. On the real component, a protrusion of 0.5-1mm per side can be sufficient for the functional protection of the system.

Therefore, by changing the bevel or bevel on both sides, sufficient free space can be created for pressing on the cam. The cams each have a bevel on the side facing away from the assembly. It is therefore conceivable that this bevel is enlarged accordingly so that one of the desired clearances is already present on at least one side of the bearing seat.

Features and details that are described in connection with a method naturally also apply in connection with the device according to the invention and vice versa, so that with regard to the disclosure of the individual aspects of the invention, mutual reference is or can always be made. In addition, an optionally described method according to the invention can be performed with the device according to the invention.

List of reference symbols

Z

Cylinder head

1

Basic camshaft

2

Sliding cam

3

Storage facility

4th

Actuator

21st

first cam group

22nd

second cam group

23

Shift gate

31

Bearing cap

32

Bearing shell

33

Bearing seat

321

first supernatant

322

second supernatant

331

first recess

332

second recess

N1

first cam

N2

second cam

N3

third cam

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed 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 102007022145 A1 [0004]
• DE 102012016674 A1 [0004]

Claims (8)

Valve drive (V) for an internal combustion engine, comprising - a basic camshaft (1), - at least one sliding cam (2) with a first cam group (21) and a second cam group (22) which are axially displaceably received on the basic camshaft (1), and - A bearing device (3) for the sliding cam (2), comprising a bearing cover (31), a bearing shell (32) and a bearing seat (33) on the sliding cam (2), wherein - the bearing seat (33) between the first group of cams ( 21) and the second cam group (22), characterized in that - the bearing seat (33) comprises an annular recess (331, 332) in at least one, preferably in both cam groups (21, 22). Valve train according to Claim 1 , characterized in that the recess (331, 332) extends in the axial direction of the sliding cam (2). Valve drive according to at least one of the preceding claims, characterized in that the bearing shell (32) has at least one protrusion (321, 322), preferably a protrusion on both sides, with respect to the bearing cover (31). Valve drive according to at least one of the preceding claims, characterized in that the bearing cover (31) and the bearing shell (32) are positively connected to one another. Valve drive according to at least one of the preceding claims, characterized in that the cam group (21, 22) has at least two cams, preferably three cams (N1, N2, N3), with different cam geometries. Valve drive according to at least one of the preceding claims, characterized in that the recess (331, 332) has a shape corresponding to the protrusion (321, 322), in particular a rectangular or wedge-shaped shape. Cylinder head (Z) of an internal combustion engine, comprising a valve drive, characterized by a valve drive (V) according to at least one of the preceding claims. Cylinder head after Claim 7 , characterized in that the bearing cover (31) is connected to the cylinder head (Z) or is partially formed from the cylinder head.

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