DE10339658B4 - Device for the variable actuation of valves by means of cams for internal combustion engines - Google Patents

Abstract

Device for the variable actuation of valves by means of cams for internal combustion engines of the following type:
- A camshaft (1) is rotatably mounted in a cylinder head (ZK) and has a fixed position to valves (2) and to Hubübertragungsanordnungen (3),
- Each of the arranged in the cylinder head (ZK), closing by spring force valve (2) is associated with one of the Hubübertragungsanordnungen (3),
a member (4) which can be pivoted to the valve stroke adjustment by means of a servomotor is fixedly mounted in the cylinder head (ZK) and has a control cam (42),
- One of a cam (11) movements transferring intermediate member (6) is prismatically supported on the pivotable element (4) and on one about the pivot axis (A4) extending, circular support curve (53) and movably guided, wherein it with the the valve (2) associated Hubübertragungsanordnung (3) is non-positively engaged, characterized in that a on the one hand with the cam (11) engages the drive lever (5) designed as a rocker arm and about an in the cylinder head (ZK) fixedly positioned axis (A5) pivotally is mounted and on the other hand with the pivotable element (4) guided intermediate member (6) frictionally engaged, wherein the intermediate member (6) has a roller (63) which both with the drive lever (5) and with the control cam (42 ) of the pivotable element (4) is engaged.

Description

The invention relates to a device for the variable actuation of valves by means of cams for internal combustion engines according to the preamble of the main claim.

Previously known is a generic device for variable actuation of valves by means of cams from the Scriptures DE 100 61 618 A1 with the following design: A camshaft rotatably mounted in the cylinder head has a fixed position to valves and their associated Hubübertragungsanordnungen, which are designed in the form of pivoting levers. These pivot levers are supported against the cylinder head, preferably via a clearance compensation element and act on the spring closing valves. An element that is variable in its position for valve lift adjustment is pivotably mounted about an axis that is fixed in the cylinder head. It has successively arranged depending on a circumferentially extending support and control curve. An intermediate member is non-positively connected to the variable in its position element, during the lifting movement sliding, prism-like supported. It stands with its U-shaped opening inner contour on both sides on the outer contour of the support and control cam engaged, is thus pivotally guided and is in addition to the cam and the valve associated Hubübertragungsanordnung engaged.

Previously known by the Scriptures DE 100 06 016 A1 a fully variable valve train for intake valves for throttle-free load control of internal combustion engines. In the cylinder head, a camshaft, a pivot lever and an adjusting means for the stroke is fixedly mounted in each case. The storage of swivel lever and adjusting means is carried out each coaxially. The pivot lever is connected via a roller with a cam in engagement, wherein on the axis of this roller, a transmission member is articulated. This transfer member is on the one hand with the stationary mounted, but pivotable adjustment means for the hub and on the other hand with a designed as a roller pivot lever valve actuator in engagement.

Previously known by the Scriptures DE 100 06 018 A1 another fully variable valve train for intake valves with a camshaft mounted in the cylinder head, in which a fixedly mounted rocker arm via a roller with one cam is engaged. At the other end of the rocker arm, a transmission member is hinged, which is on the one hand with a stationary mounted, but pivotable adjusting means and on the other hand with a roller pivot lever designed as a valve operating member engaged. The rocker arm and the adjusting means in this case have the same axis for their storage in the cylinder head.

In the two last-described embodiments of fully variable valve trains, the transmission member is indirectly moved by the interposition of a tilting or pivoting lever from the cam and each has a complex storage on the tilting or pivoting lever.

The invention has for its object to provide a generic device for variable actuation of valves with a prismatic supported on the position of its variable element intermediate member with such a kinematics that on the driven by the cam and acting directly towards the valve Hubübertragungsanordnung only minor Longitudinal forces occur. Furthermore, the respective valve lift curves should be freely adjustable in the adjustment.

According to the invention, this object is achieved in that a drive lever, which engages on the one hand with the cam, is designed as a rocker arm and is pivotably mounted about an axis fixedly positioned in the cylinder head and, on the other hand, engages with the intermediate member guided on the pivotable element.

• - Die Anwendung eines Triebhebels vermeidet das Umlenken von Ventilbetätigungskräften am Zylinderkopf. Die übertragenden Bauteile für die Hubbewegung können leichter und kompakter ausgeführt werden und die Belastung an den Eingriffsflächen und Lagerstellen wird verringert.
• - Infolgedessen, dass das Zwischenglied während der Hubbewegung eine Kombination von Schwenkbewegung und einer linearen Bewegung ausführt, verändert sich die Richtung der auf das Ventilbetätigungsglied wirkenden Kräfte nur in geringem Maße, sodass längswirkende Kräfte an der Hubübertragungsanordnung gering gehalten werden.
• - Zum Anpassen der Charakteristik der einstellbaren Ventilerhebungskurven können Eingriffskurven an unterschiedlichen Bauteilen variiert ausgeführt werden und zusammenwirken. Die Kinematik des Gesamtsystems ist damit in weiten Grenzen gestaltungsfähig.

The arrangement according to the invention affords the following advantages:

• - The application of a drive lever avoids the deflection of valve actuation forces on the cylinder head. The transmitting components for the lifting movement can be made lighter and more compact and the load on the engaging surfaces and bearings is reduced.
• As a result of the intermediate member performing a combination of pivoting movement and linear movement during the lifting movement, the direction of the forces acting on the valve actuating member varies only slightly, so that longitudinal forces on the stroke transmission arrangement are minimized.
• - To adjust the characteristics of the adjustable valve lift curves engagement curves can be performed on different components varied and cooperate. The kinematics of the overall system is thus designable within wide limits.

The features of the subclaims are explained in connection with the advantages and effects achieved in the description.

Reference to a drawing, an embodiment of the invention will be described below.

• 1 eine Seitenansicht eines erfindungsgemäßen Ventiltriebes,
• 2 eine Ansicht entsprechend 1 mit einer Stellung des schwenkbaren Elements für maximales Öffnen des Ventils bei vollwirksamem Hub des Nockens,
• 3 eine Ansicht entsprechend 2 mit einer Stellung des schwenkbaren Elements für maximales Öffnen des Ventils, jedoch beim Durchlauf des Nockengrundkreises, und dabei geschlossenem Ventil,
• 4 eine Ansicht entsprechend 1 mit einer Stellung des schwenkbaren Elements für minimales Öffnen des Ventils oder geschlossenem Ventil bei vollwirksamem Hub des Nockens,
• 5 eine Seitenansicht des schwenkbaren Elements, welches mit einer radialen Verzahnung versehen und mittels eines Schraubentriebs verstellbar ist,
• 6 eine Ansicht entsprechend 5, jedoch steht die radiale Verzahnung des schwenkbaren Elements mit einem Zahnradtrieb im Eingriff,
• 7 eine Seitenansicht des schwenkbaren Elements mit einem zugeordneten Exzenter.

Show it:

• 1 a side view of a valve gear according to the invention,
• 2 a view accordingly 1 with a position of the pivotable element for maximum opening of the valve at full stroke of the cam,
• 3 a view accordingly 2 with a position of the pivotable element for maximum opening of the valve, but during the passage of the cam base circle, and thereby closed valve,
• 4 a view accordingly 1 with a position of the pivotable element for minimum opening of the valve or closed valve at full stroke of the cam,
• 5 a side view of the pivotable element, which is provided with a radial toothing and adjustable by means of a screw drive,
• 6 a view accordingly 5 However, the radial toothing of the pivotable element is in engagement with a gear drive,
• 7 a side view of the pivotable element with an associated eccentric.

1 shows a device according to the invention for the variable actuation of valves in a schematic side view, in the cylinder head ZK a camshaft 1 with cams 11 is stored stationary. It thus has a fixed position to spring closing valves 2 and its associated Hubübertragungsanordnung 3 on. In the embodiment, the actuator is 3 as a roller lever 32 executed and with a clearance compensation element 31 and a role 33 Mistake. Likewise, in the cylinder head ZK a pivotable to the valve lift in its angular position element 4 in one axis A4 arranged stationary stored. About an actuator is by means of a servomotor, which is not shown, the pivotable element 4 posed.
A lever designed as a rocker arm 5 is one in the cylinder head ZK fixed axis A5 pivotally mounted, the axis A5 equal to the axis A4 of the pivotable element 4 is. This drive lever 5 on the one hand with the cam 11 and on the other hand with a pivotable variable element 4 guided intermediate link 6 about the role attached to it 63 engaged.
The intermediate link 6 is on the swiveling element 4 and at one around the axis A4 the storage of the swiveling element 4 extending, circular support curve and on the roller mounted on it 63 on a control curve 42 prismatically supported and thus movably guided.
In the device shown, the support curve 53 on the around the common axes A4 and A5 pivoting drive lever 5 arranged. This is kinematically favorable because of the drive lever 5 and the engagement surface 61 of the intermediate member 6 perform similar movements and thus small movements of the line of action between support curve 53 and engaging surface 61 occur.

The intermediate link 6 stands with the as a roller lever 32 executed, a valve 2 associated Hubübertragungsanordnung 3 , about its outer contour 62 and its role 33 non-positively engaged. It transmits those from the cam 11 excited and about the position of the variable element 4 certain movement to the valve 2 , The engagement of all cooperating kinematic members is by frictional connection by means of a spring force F guaranteed.
During the lifting phase of the cam 11 during the rotational movement of the camshaft 1 leads the drive lever 5 a pivoting movement, which is the intermediate member 6 defined moves. The intermediate link 6 doing a pivoting movement about the axis A4 from, at, depending on the position of the pivoting element 4 , either only this pivoting movement or an additional superimposed motion is executed.

The as a hub in the direction of the roller lever 32 and valves 2 effective, superimposed movement results from the pivoting movement and the non-positive guidance of the intermediate member 6 at the control curve 42 of the pivotable element 4 and the support curve 53 ,
2 shows a view accordingly 1 with a position of the pivotable element 4 for maximum opening of the valve 2 at full stroke of the cam 11 , The hub of the cam 11 pivots the drive lever 5 maximum and shifts the pontic 6 wherein there is a pivoting movement about the pivotable element 4 and one by the rise of the control curve 42 caused movement in the direction of the Hubübertragungsanordnung 3 executes and the valve 2 maximum opens, see H max.

3 and 4 each show the pivotable element 4 in a position for a closed valve 2 ,
The from the cam 11 certain pivotal movement of the drive lever 5 is on the intermediate link 6 transfer. When passing the base circle from the cam 11 , please refer 3 , the valve remains 2 always closed.
Likewise also remains with a position of the cam 11 with fully effective stroke the valve 2 closed, see 4 because the link 6 on a in 3 apparent arc section of the cam 42 to be led.

The valve 2 can at the above position of the pivotable element 4 and at a position of the cam 11 with fully effective stroke accordingly 4 also wanted to be slightly open. In this case, the intermediate link 6 on a slightly different from a circular contour, little rising contour of the control cam 42 be guided, but this is not shown.

The element which can be pivoted to the valve lift setting 4 is set via an actuator by a servomotor, not shown. 5 shows a solution with worm drive. The control shaft 7 has a snail 71 on that with a radial toothing 43 on the swiveling element 4 is engaged. This arrangement has the advantage that the pivotable element 4 occurring moments not radially on the adjusting 7 act and the forces occurring via the worm gear on the axial bearing of the worm in the cylinder head ZK support and thus a self-locking is guaranteed. In this solution, a worm gear with actuator is required for each cylinder.

In 6 is an actuator for the pivoting element 4 shown whose actuating shaft 7 extends in the longitudinal direction of the motor axis and for several cylinders each one or more pinions 72 having. These pinions each engage in a toothing 43 on the outer radius of an adjustable element 4 one. In this version, only one servomotor can be used for all cylinders. A disadvantage of this transmission design is the lack of self-locking, causing the adjustable element 4 acting moments as torques on the control shaft 7 Act.

7 shows an actuating drive, in which one to the pivot axis of the adjustable element 4 parallel control shaft 7 with an eccentric 73 on the support surface 44 the pivotable element attacks. The at the Excenter 73 and thus at the control shaft 7 acting moments are relatively low.

It should be mentioned that by varying the respective characteristics of support and control curve 42 the characteristic of the adjustable valve lift can be adjusted. For this purpose, the support curve is appropriate in deviation from the figures on the pivotable element 4 and arranged with this moves.

LIST OF REFERENCE NUMBERS

1

camshaft

11

cam

2

Valve

3

Hubübertragungsanordnung

31

Lash adjuster

32

roller lever

33

role

4

Swiveling element, changeable in its position

42

cam

43

radial toothing

44

support surface

5

drive lever

51

Role at 5

52

Engaging surface at 5 for 63

53

support curve

6

intermediary

61

Engaging surface at 53

62

outer contour

63

role

7

actuating shaft

71

slug

72

pinion

73

eccentric

A4 / A5

Swivel axis of 4 and 5

ZK

cylinder head

F

Spring force, which attacks at 6 and against 3; 4 and 5 urges

Claims (8)

Device for the variable actuation of valves by means of cams for internal combustion engines having the following construction: - a camshaft (1) is rotatably mounted in a cylinder head (ZK) and has a fixed position to valves (2) and to Hubübertragungsanordnungen (3), - each of arranged in the cylinder head (ZK), closing by means of spring force valve (2) is assigned in each case one of the Hubübertragungsanordnungen (3), - a valve lift adjustment by means of a servomotor pivotable element (4) is mounted in the cylinder head (ZK) stationary and has a control cam ( 42), - one of a cam (11) movements transmitting intermediate member (6) on the pivotable element (4) and on one about the pivot axis (A4) extending, circular support curve (53) prismatically supported and movably guided, wherein with the valve (2) associated Hubübertragungsanordnung (3) frictionally engaged, characterized in that on the one hand with the Cam (11) engages the drive lever (5) designed as a rocker arm and about a cylinder head (ZK) fixedly positioned axis (A5) is pivotally mounted and on the other hand with the on pivotable element (4) guided intermediate member (6) is frictionally engaged, wherein the intermediate member (6) has a roller (63) which both with the drive lever (5) and with the control cam (42) of the pivotable element (4) is engaged. Setup after Claim 1 , characterized in that the pivot axis (A4) of the pivotable element (4) and the pivot axis (A5) of the drive lever (5). Device according to one of the preceding claims, characterized in that the Hubübertragungsanordnung (3) for the valve (2) as a roller (33) provided with a roller lever (32), which can be designed as a pan or rocker arm, or designed as a bucket tappet is. Device according to one of the preceding claims, characterized in that on the pivotable element (4) guided intermediate member (6) under the action of a spring force (F), whose direction of action it with the pivotable element (4) and the drive lever (5) and indirectly with the cam (11) is engaged. Device according to one of the preceding claims, characterized in that the circular support curve (53) for the intermediate member (6) on the about the pivot axis (A4) of the variable element (4) mounted first drive lever (5) is arranged. Device according to one of the preceding claims, characterized in that the circular support curve (53) for the intermediate member (6) on the variable element (4) is arranged and in a part of the engagement region of the intermediate member (6) of a circular contour around the pivot axis ( A4) is designed differently. Device according to one of the preceding claims, characterized in that designed as a pan or rocker arm or bucket tappet Hubübertragungsanordnung (3) has an engagement curve in the position of the closed valve (2) by a radius about the pivot axis (A4) of the pivotable element (4) is described. Device according to one of the preceding claims, characterized in that the pivotable element (4) has a toothing (43) for adjustment by means of a screw (71) or a pinion (72).

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