DE102007057811B4 - Valve drive for gas exchange valves of an internal combustion engine - Google Patents

Abstract

Valve gear (1) for actuating gas exchange valves (2) of three cylinders arranged in series behind one another of an internal combustion engine, with a basic camshaft (3) and six cam groups (5, 6, 7, 8, 9,) displaceable in the longitudinal direction of the base camshaft (3) 10), each having at least two different cam tracks (18, 19), wherein the six cam groups (5, 6, 7, 8, 9, 10) for the gas exchange valves (2) of the three cylinders in the circumferential direction of the base camshaft (3) in pairs offset vertices (S), characterized in that all six cam groups (5, 6, 7, 8, 9, 10) are formed on a single, on the base camshaft (3) axially displaceable cam carrier (4), wherein the vertex ( S) of the cam tracks (18, 19) of the cam groups (7, 8) of the gas exchange valves (2) of the middle cylinder each an angular distance of 50 to 70 degrees from the vertices (S) of the cam tracks (18, 19) of the cam groups (5, 6, 9, 10) the gas exchange Have selventile the outer cylinder, and wherein the six cam groups (5, 6, 7, 8, 9, 10) have a common base circle portion (20).

Description

The present invention relates to a valve train for gas exchange valves of an internal combustion engine according to the preamble of claim 1 and an internal combustion engine with such a valve train.

From the WO 2004/083611 A1 A valve train of an internal combustion engine is already known in which a total of eight cam groups are provided for driving eight intake or exhaust valves of a 4-cylinder in-line engine along an intake or exhaust camshaft. Each of the eight cam groups has two cams arranged one behind the other in the longitudinal direction of the camshaft, which cams originate from a common base circle section, but which have cam tracks with different peak heights or phase positions. By displacing the cam sets axially along the camshaft while the base circle portion abuts against valve actuation means of the intake and exhaust valves to engage another cam track with the valve actuation means, the lift height or opening time of these valves may be varied, for example at Cold start of the internal combustion engine for a faster heating of an exhaust aftertreatment device and thus to ensure a reduction in exhaust emissions.

In the known valve train each serving for controlling the gas exchange valves of a single cylinder cam groups are formed in pairs on a cam carrier which is axially displaceable on the camshaft. For displacement of each of the four individual cam carrier two axially spaced worm gears are provided in each case. The worm gears include a left hand or right hand helical or helical groove in the cam carrier that is engageable by an actuator of an associated worm drive to move the cam carrier on the camshaft to the left or to the right, respectively.

Since in this arrangement, on the one hand, a larger number of worm drives or actuators is required and on the other hand taken by these worm drives or actuators relatively much space in the cylinder head housing was in the DE 10 2005 006 489 A1 the Applicant has already proposed to couple two cam carrier adjacent cylinder together and provide common worm drives or actuators for the coupled together cam carrier. The coupling of two adjacent cam carrier is particularly suitable for internal combustion engines with an even number of cylinders per cylinder row, since there all cam carriers can be combined into pairs.

From the prior art is still the document EP 0 579 592 A1 known. This relates to an internal combustion engine with at least one camshaft axially displaceable by an adjusting device. In order to move the camshaft axially in response to the camshaft rotation, in this document, an adjustment consisting of a sliding link with two helical, mutually opposite directions of rotation guide grooves that terminate in annular clearance grooves, and a deflectable by a trigger member in the guide grooves driver , proposed. Furthermore, the prior art shows the document DE 10 2005 020 236 A1 , This relates to the valve train of an internal combustion engine with a basic camshaft, are arranged on the axially displaceable cam carrier. It is envisaged that for mounting the camshaft to a cylinder head, the cam carriers are displaced by spacers in an assembly position.

Proceeding from this, the invention has the object, further develop a valve train of the type mentioned in that it is suitable at least for some internal combustion engines with an odd number of cylinders per cylinder bank.

Surprisingly, this object has been achieved, at least in certain engines, by combining the cams for actuating the intake and / or exhaust valves of three adjacent cylinders on a single cam carrier. This is particularly advantageous in those internal combustion engines in which the number of cylinders per cylinder bank is odd and / or is a multiple of three, especially in 3-, 6-, 9- or 12-cylinder engines. It is further provided that the six cam groups for the gas exchange valves of the three cylinders in the circumferential direction of the base camshaft have pairs offset vertices, the vertices of the cam tracks of the cam groups of the gas exchange valves of the middle cylinder each an angular distance of 50 ° to 70 ° from the apex of the cam tracks Have cam groups of the gas exchange valves of the outer cylinder, and wherein the six cam groups have a common base circle section.

The solution according to the invention not only further reduces the number of worm drives or actuators required per cylinder, but also the space required for accommodating the same within the cylinder head housing.

According to a particularly preferred embodiment of the invention, the displacement of the individual cam carrier by means of two worm gears whose actuators are fixedly mounted in the cylinder head and each having an actuator, wherein the two actuators selectively or alternately brought by actuation of the actuators with the cam carrier into engagement can be moved to move it in opposite directions. The two actuators are preferably mounted at an axial distance from each other on both sides of the central cylinder fixed in the cylinder head, so that their actuators each bring between one of the two groups of cylinders of this cylinder and an adjacent cam group of one of the two outer cylinder with the cam carrier in engagement. The intervention is expediently carried out in that upon activation, the actuator of the respective actuator is extended and brought into engagement with an actuator opposite screw or helical groove on the cam carrier in the one worm drive left-handed and the other worm drive right-handed.

It is envisaged that the six cam groups for the gas exchange valves of the three cylinders in pairs in the circumferential direction of the base camshaft staggered vertices have, but have a common base circle portion, so that the cam carrier can be moved by activation of one of the two actuators, during valve actuation means of the gas exchange valves to be actuated abut against the common base circle section.

The vertexes of the two groups of cams, which serve to actuate the gas exchange valves of the middle cylinder, preferably have in the circumferential direction of the base camshaft at an angular distance of 50 to 70 degrees from the apexes of the two pairs of cam groups, each serving to actuate the gas exchange valves of the two outer cylinders , The common base circle section expediently extends over a circumferential angle of between 100 and 120 degrees, and preferably over a circumferential angle of approximately 110 degrees.

In the following the invention will be explained in more detail with reference to an embodiment shown in the drawing. Show it:

1 a schematic side view of a valve train for six intake or exhaust valves of three in-line cylinders of an internal combustion engine;

2 a schematic end view of the valve gear in the direction of the arrows II in 1 ,

The valve gear shown in the drawing 1 serves to control the intake valves 2 of three cylinders (not shown) arranged one behind the other in an internal combustion engine. The valve train 1 allows it by means of an overhead, rotatably mounted in a cylinder head housing of the engine base camshaft or camshaft 3 the stroke of the six intake valves 2 to adjust the three cylinders together.

For this purpose, the valve train includes 1 in the range of three cylinders a single rotationally fixed and axially displaceable on the camshaft 3 mounted cam carrier 4 , the total of six axially spaced cam groups 5 . 6 . 7 . 8th . 9 . 10 having. Each of the six cam groups 5 . 6 . 7 . 8th . 9 . 10 on the cam carrier 4 has two cams 5a . 5b . 6a . 6b . 7a . 7b . 8a . 8b . 9a . 9b . 10a . 10b on, one of each with a roll 11 a pivotally mounted roller finger follower 12 from one of the valves 2 interacts about the role 11 a in 2 shown in broken lines, at the bottom with a valve plate 13 provided valve member 14 of the respective intake valve 2 to operate, which is to open the valve 2 against the force of a valve spring 15 in the cylinder head can be pushed down. The valve train 1 also includes for each of the valves 2 a likewise in 2 shown in broken lines hydraulic valve clearance compensation element 16 ,

Every pair of cams 5a . 5b . 6a . 6b . 7a . 7b . 8a . 8b . 9a . 9b . 10a . 10b each cam group 5 . 6 . 7 . 8th . 9 . 10 has two different cam tracks 18 respectively. 19 on, characterized by axial displacement of the cam carrier 4 on the camshaft 3 between two displacement positions optionally with the roller 11 of the rocker arm 12 the associated valve 2 can be brought into abutting contact. 1 shows one of the two displacement positions in which the left cams 5a . 6a . 7a . 8a . 9a . 10a all cam groups 5 . 6 . 7 . 8th . 9 . 10 with the role 11 of the rocker arm 12 interact.

How best in 1 shown, is the arrangement of the two cams 5a . 5b . 6a . 6b . 7a . 7b . 8a . 8b . 9a . 9b respectively. 10a . 10b at each cam group 5 . 6 . 7 . 8th . 9 . 10 the same, ie the left cams 5a . 6a . 7a . 8a . 9a . 10a each cam group 5 . 6 . 7 . 8th . 9 . 10 each have the same shape of cam track with each other 18 on, as well as the right cam 5b . 6b . 7b . 8b . 9b . 10b all cam groups 5 . 6 . 7 . 8th . 9 . 10 each other also the same shape of cam track 19 own, so that in each of the two displacement positions of the cam carrier 4 all valves 2 be operated in the same way.

On the other side, the crests S of the cam tracks 18 . 19 two adjacent cams 5a . 5b respectively. 6a . 6b respectively. 7a . 7b respectively. 8a . 8b respectively. 9a . 9b respectively. 10a . 10b each cam group 5 . 6 . 7 . 8th . 9 . 10 different distances from the axis of rotation 17 the camshaft 3 on, so the intake valves 2 be completely open when in the in 1 Displacement position shown, the higher left cam 5a . 6a . 7a . 8a . 9a . 10a each cam group 5 . 6 . 7 . 8th . 9 . 10 above the rollers 11 the associated rocker arm 12 are arranged and interact with these while the intake valves 2 only partially open when in the other displacement position of the cam carrier, not shown 4 the flatter right cams 5b . 6b . 7b . 8b . 9b . 10b each cam group 5 . 6 . 7 . 8th . 9 . 10 with the roles 11 the rocker arm 12 interact.

In addition, also the shape of the two cams 5a . 5b respectively. 6a . 6b respectively. 7a . 7b respectively. 8a . 8b respectively. 9a . 9b respectively. 10a . 10b each cam group 5 . 6 . 7 . 8th . 9 . 10 be different, or the crests S of the left cams 5a . 6a . 7a . 8a . 9a . 10a each cam group 5 . 6 . 7 . 8th . 9 . 10 can in the circumferential direction of the camshaft 3 by the same angle with respect to the vertices S of the right cams 5b . 6b . 7b . 8b . 9b . 10b be offset so that the valves 2 remain open for different periods of time or be opened and / or closed at different times.

How best in 2 shown, have all cam groups 5 . 6 . 7 . 8th . 9 . 10 on the cam carrier 4 a common base circle section 20 on, its outer diameter over the axial length of each cam group 5 . 6 . 7 . 8th . 9 . 10 is the same and extends over a rotational or circumferential angle α of about 110 degrees.

As in 2 on the cams 5a . 6a . 7a is visible, are also the vertices S of the cams 5a . 5b . 6a . 6b respectively. 7a . 7b . 8a . 8b respectively. 9a . 9b . 10a . 10b of the two pairs of cam groups 5 . 6 respectively. 7 . 8th respectively. 9 . 10 each cylinder in the circumferential direction of the camshaft 3 offset against each other. At the in 2 illustrated embodiment is in the direction of rotation of the camshaft (arrow A), the angular distance from the center M of the common base circle portion 20 to the vertices S of the higher cams 5a . 6a at the two with the valves 2 of the first cylinder cooperating cam groups 5 and 6 about 120 degrees, while the angular distance from the center M of the common base circle section 20 to the vertices S of the corresponding cams 7a . 8a respectively. 9a . 10a the two with the valves 2 of the second middle cylinder and the third cylinder cooperating cam groups 7 and 8th respectively. 9 and 10 about 180 degrees or about 240 degrees. The ignition timing and the firing order of the individual cylinders is adapted to these angular distances.

To the cam carrier 4 rotatably with the camshaft 3 but its axial displacement along the camshaft 3 to allow, has the hollow cylindrical cam carrier 4 at its inner periphery on a longitudinal toothing, which meshes with a complementary external toothing on the camshaft, as in 2 at 21 shown.

The axial displacement of the cam carrier 4 on the camshaft 3 for adjusting the stroke and / or the opening times of the intake valves 2 takes place as needed and is always carried out when the common base circle section 20 all cam groups 5 . 6 . 7 . 8th . 9 . 10 during the rotational or circumferential angle α of the camshaft 3 from about 110 degrees to the rollers 11 the rocker arm 12 opposite. The degree of axial displacement of the cam carrier 4 between its two displacement positions corresponds to the center distance of adjacent cams 5a . 5b respectively. 6a . 6b respectively. 7a . 7b respectively. 8a . 8b respectively. 9a . 9b respectively. 10a . 10b or cam tracks 18 . 19 each cam group 5 . 6 . 7 . 8th . 9 . 10 ,

The displacement of the cam carrier 4 from its instantaneous displacement position in the respective other displacement position takes place with the help of two worm gears 22 . 23 that the cam carrier 4 on the camshaft 3 each move in opposite directions. The two worm drives 22 . 23 each comprise a fixedly mounted within the cylinder head housing of the internal combustion engine actuator 24 . 25 with a movable driving pin 26 . 27 which, if necessary, leaves the actuator 24 . 25 extends to its free end with an opposite helical or helical groove 28 . 29 in the outer peripheral surface of a grooved disc 30 . 31 of the cam carrier 4 engage and thereby the cam carrier 4 to move in the axial direction.

How best in 1 is shown, which is one of the two grooved wheels 30 between the right cam 6b the right cam group 6 the left outer cylinder and the adjacent left cam 7a the left cam group 7 the second middle cylinder of the three cylinders arranged, while the other of the two grooved wheels 31 between the right cam 8b the right cam group 8th of the second middle cylinder and the adjacent left cam 9a the left cam group 9 the right outer cylinder of the three cylinders is arranged.

The screw or helical groove 28 in the outer peripheral surface of the grooved disc 30 of the cam carrier 4 is left-handed to the cam carrier 4 when engaging the driving pin 26 of the associated actuator 24 to move to the right while the helical or helical groove 29 in the outer peripheral surface of the grooved disc 31 right is to the cam carrier 4 when engaging the driving pin 27 of the associated actuator 25 to move to the left.

To the cam carrier 4 in relation to the axis of rotation 17 the camshaft 3 to center or during its displacement in relation to the axis of rotation 17 centered is the cam carrier 4 each between the two valves 2 each cylinder by means of a sliding bearing (not shown) rotatably mounted. The opposite end faces of one or more plain bearings can simultaneously form abutment surfaces to a displacement of the cam carrier 4 To prevent beyond the desired displacement position.

LIST OF REFERENCE NUMBERS

1

valve train

2

Valve, gas exchange valve

3

Basic camshaft, camshaft

4

cam support

5

cam group

6

cam group

7

cam group

8th

cam group

9

cam group

10

cam group

11

role

12

cam follower

13

valve disc

14

valve member

15

valve spring

16

Lash adjuster

17

axis of rotation

18

Cam track

19

Cam track

20

Base circle portion

21

Spline / external teeth

22

worm drive

23

worm drive

24

Actuator, actuator

25

Actuator, actuator

26

Driving pin, actuator

27

Driving pin, actuator

28

left-hand groove

29

right-hand groove

30

grooved disc

31

grooved disc

A

direction of rotation

S

vertex

α

Turning or circumferential angle

Claims (12)

Valve train ( 1 ) for actuating gas exchange valves ( 2 ) of three cylinders arranged one behind the other in an internal combustion engine, with a basic camshaft ( 3 ) and six in the longitudinal direction of the basic camshaft ( 3 ) displaceable cam groups ( 5 . 6 . 7 . 8th . 9 . 10 ), each having at least two different cam tracks ( 18 . 19 ), wherein the six cam groups ( 5 . 6 . 7 . 8th . 9 . 10 ) for the gas exchange valves ( 2 ) of the three cylinders in the circumferential direction of the basic camshaft ( 3 ) have vertices (S) offset in pairs, characterized in that all six cam groups ( 5 . 6 . 7 . 8th . 9 . 10 ) on a single, on the base camshaft ( 3 ) axially displaceable cam carrier ( 4 ) are formed, wherein the vertices (S) of the cam tracks ( 18 . 19 ) of the cam groups ( 7 . 8th ) of the gas exchange valves ( 2 ) of the middle cylinder in each case an angular distance of 50 to 70 degrees from the vertices (S) of the cam tracks ( 18 . 19 ) of the cam groups ( 5 . 6 ; 9 . 10 ) of the gas exchange valves of the outer cylinder, and wherein the six cam groups ( 5 . 6 . 7 . 8th . 9 . 10 ) a common base circle section ( 20 ). Valve train ( 1 ) according to claim 1, characterized in that the common base circle section ( 20 ) of the six cam groups ( 5 . 6 . 7 . 8th . 9 . 10 ) in the circumferential direction of the basic camshaft ( 3 ) extends over an angle (α) between 100 and 120 degrees. Valve train ( 1 ) according to claim 2, characterized in that the common base circle section ( 20 ) of the six cam groups ( 5 . 6 . 7 . 8th . 9 . 10 ) in the circumferential direction of the basic camshaft ( 3 ) extends over an angle (α) of 110 degrees. Valve train ( 1 ) according to one of claims 1 to 3, characterized in that the angular distance from the center (M) of the common base circle section ( 20 ) to crests (S) of the cam tracks ( 18 . 19 ) of cams ( 5a . 6a ) with the gas exchange valves ( 2 ) of a first cylinder of the series cooperating cam groups ( 5 . 6 ) between 110 and 130 degrees, that the angular distance from the center (M) of the common base circle section ( 20 ) to crests (S) of the cam tracks ( 18 . 19 ) of cams ( 7a . 8a ) with the gas exchange valves ( 2 ) of a second cylinder of the series cooperating cam groups ( 7 . 8th ) is between 170 and 190 degrees, and that the angular distance from the center (M) of the common base circle section ( 20 ) to crests (S) of the cam tracks ( 18 . 19 ) of cams ( 9a . 10a ) with the gas exchange valves ( 2 ) of the third cylinder of the series cooperating cam groups ( 9 . 10 ) is between 230 and 250 degrees. Valve train ( 1 ) according to one of the preceding claims, characterized by two worm gears ( 22 . 23 ) for moving the cam carrier ( 4 ) in opposite directions. Valve train ( 1 ) according to claim 5, characterized in that actuators ( 26 . 27 ) of actuators ( 24 . 25 ) of the worm gears ( 22 . 23 ) optionally with the cam carrier ( 4 ), while a common base circle section ( 20 ) of the six cam groups ( 5 . 6 . 7 . 8th . 9 . 10 ) against valve actuation means ( 11 ) of the gas exchange valves ( 2 ) is present Valve train ( 1 ) according to claim 5 or 6, characterized in that actuators ( 26 . 27 ) of actuators ( 24 . 25 ) of the worm gears ( 22 . 23 ) between a cam ( 7a ; 8b ) of a cam group ( 7 ; 8th ) of the middle cylinder and an adjacent cam ( 6b ; 9a ) of a cam group ( 6 ; 9 ) of one of the two outer cylinders with the cam carrier ( 4 ). Valve train ( 1 ) according to claim 6 or 7, characterized in that an actuator ( 26 ) of the actuators ( 26 . 27 ) of the two actuators ( 24 . 25 ) with a left-handed helical or helical groove ( 28 ) on the cam carrier ( 4 ) while the other actuator ( 27 ) of the actuators ( 26 . 27 ) of the two actuators ( 24 . 25 ) with a right-handed helical or helical groove ( 29 ) on the cam carrier ( 4 ). Valve train ( 1 ) according to claim 8, characterized in that the helical or helical grooves ( 28 . 29 ) in grooved discs ( 30 . 31 ) of the cam carrier ( 4 ) between two cam groups ( 6 . 7 ; 8th . 9 ) are formed. Internal combustion engine, characterized by at least one valve drive ( 1 ) according to one of the preceding claims. Internal combustion engine according to claim 10, characterized in that it comprises more than two rows of cylinders. Internal combustion engine according to claim 10 or 11, characterized in that it is a W-motor.

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