WO2009033884A1

WO2009033884A1 - Valve actuating means for a fully-variable valve drive

Info

Publication number: WO2009033884A1
Application number: PCT/EP2008/060052
Authority: WO
Inventors: Peter Sailer; Michael Schewe; Sebastian Zwahr; Jens Schäfer
Original assignee: Schaeffler Kg
Priority date: 2007-09-06
Filing date: 2008-07-31
Publication date: 2009-03-19
Also published as: DE102007042457A1

Abstract

The invention relates to a valve drive of an internal combustion engine, composed of a three-dimensional cam of a valve camshaft and also an actuating means which is in contact with at least one charge-exchange valve, wherein the actuating means is designed as a cup tappet (1a) and has, on its side which faces toward the cam, two opposite projections (2a, 2b), in the circular-arc-shaped cutouts of which is pivotably mounted a rocker (3), wherein said rocker (3) is in contact with the cam.

Description

Name of the invention

Valve actuator for a fully variable valve lift

description

Field of the invention

The invention relates to a valve train of an internal combustion engine, comprising a three-dimensional formed cam of a valve camshaft and an actuating means in contact with at least one charge exchange valve.

Background of the invention

Gasoline engines are generally operated by means of a quantitative load control, i. H. the quantity of mixture required for operating the engine is regulated depending on the load. For this purpose, a throttle valve is usually arranged in the intake tract of the engine to throttle the combustion chamber supplied combustion air and thus adjust the required amount.

In low load points of the engine, a correspondingly small amount of mixture is required for operation and, accordingly, a small one

Air volume. This means that sucked in these operating points

Fresh air is throttled very strong. By this strong throttling the motor works against a vacuum, which leads to an increase of the losses and a reduction of the efficiency. These losses, also referred to as throttle losses, lead to an increase in the fuel consumption of the engine. In order to minimize these losses, nowadays fully variable valve trains are used, in which valve lifts and opening periods adapted to the respective operating points of the engine can be realized. By this measure, therefore, an individual time valve opening cross section can be displayed for the respective operating point of the engine and thus the required amount of air can be controlled via the intake valves of the engine. This means that a throttle valve can be omitted and thus the intake tract of the engine can be largely throttled, which significantly reduces the losses of the engine.

An embodiment of a fully variable valve train of interest here represents a three-dimensional design of the cam of the valve camshaft in combination with corresponding actuation means of the charge exchange valves. To realize the different valve strokes and opening durations, this space cam is axially displaceable relative to the actuation means and rotatable relative thereto. As an actuating means find in this area known to those skilled classic variants such. As tappets or drag lever, their use.

State of the art

EP 0 777 039 B1 discloses such a fully variable valve drive with room cams, wherein either tappets or cam followers are used as actuation means for actuating the charge cycle valves. In order to follow the contour of the three-dimensional cam, a convex spacer is arranged between the cam and the actuating means.

A disadvantage of the known solution is the design of the tappet as a completely round cup shape with weight disadvantages and the high manufacturing effort for the spherical configurations of components of the actuating mechanism. task

The invention is therefore based on the object to provide a fully variable valve train, which reduces the manufacturing cost and weight is reduced.

Summary of the invention

The object is achieved on the basis of the preamble of the independent claims in conjunction with the respective characterizing features. Developing measures of the invention are achieved in the respective dependent claims.

According to one of the independent claims, the object is achieved in that the actuating means is designed as a bucket tappet and this has on its side facing the cam on two opposing projections, in whose arcuate recesses a rocker is rotatably mounted, said rocker with the cam in Contact stands. By this measure, material can be saved in the design of the teat, which reduces the production costs and leads to weight advantages. In addition, a realization of a fully variable valve train is possible by the rotatable mounting of the rocker.

In a further development of the invention, the rocker is provided with a cam roller which is in contact with the cam. The advantage here is that the friction of the system can be significantly reduced by the rolling of the cam on the cam roller, resulting in an increase in the efficiency of the valve train. In a further embodiment of the invention, the axis of the radius of the rocker extends almost through the contact area rocker to cam. As a result, the pivot point of the rocker almost drops to the point of contact, and thus a displacement of the system due to a lever arm during operation is largely avoided.

In a further development of the invention, the axis of the radius of the rocker extends almost through the contact region of the cam roller to cam. As a result, the pivot point of the rocker is placed almost at the point of contact of the roller and cam and thus prevents a shift of the system during operation in the variant with cam roller.

In a further embodiment of the invention, the cam roller is designed as a rolling bearing or sliding bearing. This allows a further reduction in the friction of the system can be achieved, which reduces the losses and thus increases the efficiency of the valve train.

In a further development of the invention, the bucket tappet has a central web in the area of the rocker in order to reduce the deflection of the rocker during operation. By this measure, the rigidity of the system is increased since the rocker also has a contact surface on the bucket tappet next to the cheek areas , A lower deflection increases the reliability of the introduction of force and thus leads to a desired opening and closing of the charge exchange valves.

In a further embodiment of the invention, the sliding rocker is formed as a straight or curved surface. A curved surface reduces the contact friction when in contact with the cam of the camshaft, whereas a straight surface is characterized by a low manufacturing cost. Thus, the shape of the sliding rocker can be adapted to the respective requirements of the system. According to another of the independent claims, the valve train is configured such that the actuating means is designed as a bucket tappet and this has on its side facing the cam on two opposing arcuate projections, each having a circular recess in which a via a Gleitabgriffelement with the Cam in contact bolt is guided. By this design of the bucket tappet material can be saved, which leads to weight advantages and reduces the production cost. In addition, an interaction with a three-dimensional cam is possible by the combination of the bolt with the Gleitabgriffelement.

In a further development of the invention, pivoting of the sliding tapping element relative to the tappet is only possible to a limited extent. By this measure, the assembly of the valve train in the internal combustion engine is simplified. This can be realized by arranged in the region of Gleitabgriffelements pins.

In a further embodiment of the invention, the bolt is designed as a rolling bearing or as a sliding bearing. The advantage here is that the friction of the system is reduced during operation and thus an improvement in the efficiency of the valve train is recorded.

According to another of the independent claims, the valve train defined in the O-term is designed such that the actuating means is designed as a combination of a bridge and two bucket tappets for the simultaneous operation of two charge exchange valves and the bridge has on the side facing the cam via a sliding rocker, which is pivotally mounted in the bridge in a circular structure to follow the contour of the cam can. By this measure, the simultaneous driving of two charge exchange valves with low production cost is possible, while interacting with a three-dimensional cam. In a further development of the invention, the sliding rocker is pivotably mounted about an axis parallel or orthogonal to the longitudinal center axis of the bridge. By this measure, a parallel or vertical arrangement of the bridge can take place relative to the valve camshaft of the internal combustion engine. Thus, an adaptation to the space requirements of the internal combustion engine is possible.

In a further embodiment of the invention, the bridge has on its side facing the charge exchange valves via two recesses which correspond to the top of the tappets. As a result, the use of standard cup rams in combination with the bridge is possible, so it can be used on series parts, which reduces the manufacturing cost.

According to another of the independent claims, the valve train according to the invention is characterized in that the actuating means consists of a drag lever, which is mounted at its one end via a support member in the cylinder head and is at its other end with a bucket tappet for translational movement of a charge exchange valve in contact wherein the rocker arm can perform a tilting movement relative to the bucket tappet about its longitudinal center axis to follow the contour of the cam. This makes it possible to realize a valve drive with drag lever, in which the production costs are low and operation with a three-dimensional cam is possible.

In a further development of the invention, the tappet from its side facing the finger follower has a circular arc-like recess and the cam follower has a corresponding rounding to allow a relative movement between the two components. As a result, a robust connection with low production costs is realized. embodiments

Brief description of the drawings

Further, measures improving the invention will be described in more detail below together with the description of preferred embodiments of the invention with reference to FIGS. It shows:

1 shows a perspective view of the valve drive according to the invention consisting of a bucket tappet with rocker,

2 shows a perspective view of the valve drive, consisting of a bucket tappet and a rocker with cam roller,

3 shows a perspective view of the tappet,

4 shows a perspective view of the valve drive with Gleitabgriffelement and bolts,

5 shows a perspective view of the arrangement with two bucket tappets and bridge with rocker,

6 is a perspective view of the bridge, and

7 is a perspective view of the valve train with cam follower and bucket tappets.

Detailed description of the drawings

In Figure 1, an inventive valve train according to one of the independent claims is shown, which consists essentially of the bucket tappet 1 a and 3 of the rocker. The rocker 3 is in a circular arc savings of the projections 2a and 2b of the tappet 1 a out and can perform a pivotal movement relative to the tappet 1 a on this.

In addition, the rocker 3 is on its surface with a cam, not shown, a valve camshaft in contact. At the lower end of the tappet 1 a is usually, not shown here, arranged a charge exchange valve of the internal combustion engine.

During operation of the internal combustion engine, a movement in the opening direction of the charge exchange valve is transmitted to the rocker 3 and thus to the tappet 1 a through the cam of the camshaft, which leads to an opening of the charge exchange valve. Due to the possible relative movement between the bucket tappet 1 a and the rocker 3, the rocker 3 can also perform a rotation and thus follow the contour of a room cam.

In contrast, a cam roller 4 is arranged in Figure 2 in the middle of the rocker 3. In this case, this cam roller 4 is in contact with the cam of the valve camshaft, not shown, via which the valve opening movement is introduced into the system.

In Figure 3, the tappet 1 a is shown as a single view. This has in its central region, between the two projections 2a and 2b, via a central web 5. By this, the rigidity of the system is increased and reduced during operation, the deflection of the rocker 3, not shown in this case.

FIG. 4 shows a valve drive according to the invention in accordance with a further independent claim which consists of a cup tappet 1 a 'and a pin 7 provided with a sliding tappet element 6. The bolt 7 is in this case in circular projections 2a 'and 2b' of the tappet 1 a 'out. In addition, in one of the two projections 2a 'pins 13a and 13b arranged, which allow pivoting of the bolt 7 and thus the Gleitabgriff- element 6 only to a certain extent. The Gleitabgriffelement 6 is in contact with a cam, not shown, of the valve camshaft of the internal combustion engine. Also in this case, a charge exchange valve of the internal combustion engine is arranged at the lower end of the tappet 1 a '.

During operation of the internal combustion engine, a translatory movement in the direction of the charge exchange valve is introduced via the Gleitabgriffelement 6 through the cam of the camshaft in the system.

FIG. 5 shows a valve drive according to a further independent claim. This consists of two tappets 1 a "and 1 b", which are operated via a common bridge 8 and a rocker 3 "mounted in this bridge 8. This bridge 8 is shown as an individual part in FIG two circular recesses 9a and 9b, in which the tappets 1 a "and 1 b" are arranged.

In operation, the rocker 3 is in contact with a cam of the camshaft and transmits in accordance with the contour of this cam a translatory movement in the opening direction of the charge exchange valves in the system.

7 shows a further valve train according to the invention, which consists essentially of a drag lever 10 in conjunction with a bucket tappet 1 a '. "The drag lever 10 is on one side via a support element 11 in a cylinder head, not shown stored the engine and on its other side so with the bucket tappet 1 a '"connected, he can perform with respect to this a pivotal movement about its longitudinal central axis.

This is realized by the fact that the tappets 1 a '"at its upper end has a circular recess, which is a rounded Form of the cam lever 10 corresponds. In addition, the drag lever 10 is with its role with a cam 14 of a camshaft in contact. When the internal combustion engine is operating, a charge exchange valve attached to the lower end of the tappet 1 a '"is opened in the manner known to the person skilled in the art.

LIST OF REFERENCE NUMBERS

1 a, 1 b bucket tappets

2a, 2b Projections 3 Rocker

4 cam roller

5 middle bridge

6 sliding tapping element

7 bolt 8 bridge

9a, 9b recesses

10 rocker arms

11 support element

12 surface rocker 13a, 13b pins

14 cams

Claims

claims

1. Valve gear of an internal combustion engine, consisting of a three-dimensionally formed cam of a valve camshaft and with at least one charge exchange valve in contact actuating means, characterized in that the actuating means is designed as a bucket tappet (1 a) and this on its side facing the cam over two has opposite projections (2a, 2b), in whose circular arc-shaped recesses a rocker (3) is pivotally mounted, said rocker (3) is in contact with the cam.

2. Valve drive according to claim 1, characterized in that the rocker (3) with a cam roller (4) is provided, which is in contact with the cam.

3. Valve drive according to claim 1, characterized in that the axis of the radius of the rocker (3) extends almost through the contact area rocker (3) to cam.

4. Valve drive according to claim 2, characterized in that the axis of the radius of the rocker (3) extends almost through the contact area cam roller (4) to cam.

5. Valve drive according to claim 2 or 4, characterized in that the cam roller (4) is designed as a rolling bearing or as a sliding bearing.

6. Valve drive according to one of the preceding claims, characterized in that the tappet (1 a) in the region of the rocker (3) via a central web (5) has to reduce their deflection during operation.

7. Valve drive according to claim 1 or 3 or 6, characterized in that the rocker (3) is designed as a straight or curved surface (12).

8. Valve gear of an internal combustion engine, consisting of a three-dimensionally formed cam of a valve camshaft and with at least one charge exchange valve in contact actuating means, characterized in that the actuating means as a bucket tappet (1 a) is formed and this on its side facing the cam over two opposite circular arc-shaped protrusions (2a, 2b) has, each having a circular recess in which a via a Gleitabgriffelement (6) with the cam in contact standing bolt (7) is pivotally guided.

9. Valve drive according to claim 8, characterized in that a pivoting of Gleitabgriffelements (6) relative to the tappet (1 a) is possible only to a limited extent.

10. Valve gear according to claim 8 or 9, characterized in that the bolt (7) is designed as a rolling bearing or sliding bearing.

11. Valve drive of an internal combustion engine, consisting of a three-dimensionally formed cam of a valve camshaft and an at least one charge exchange valve in contact with actuating means, characterized in that the actuating means as a combination of a bridge (8) and two bucket tappets (1 a, 1 b ) is designed for the simultaneous operation of two charge exchange valves and the bridge (8) on the side facing the cam via a rocker (3), which in the bridge (8) is pivotally mounted in a circular arc-shaped recess to the contour of the cam to be able to follow.

12. Valve drive according to claim 11, characterized in that the rocker (3) is pivotally mounted about an axis parallel to the longitudinal center axis of the bridge (8) or orthogonal axis.

13. Valve drive according to claim 11 or 12, characterized in that the bridge (8) on its side facing the charge exchange valves via two recesses (9a, 9b), which correspond to the top of the tappets (1 a, 1 b).

14. Valve drive of an internal combustion engine, consisting of a three-dimensionally formed cam of a valve camshaft and an at least one charge exchange valve in contact actuating means, characterized in that the actuating means comprises a drag lever (10), which at one end via a Ab- support element ( 11) is mounted in a cylinder head and at its other end with a bucket tappet (1 a) for translational movement of a charge exchange valve in contact, wherein the drag lever (10) relative to the bucket tappet (1 a) is pivotally mounted about its longitudinal central axis to the Contour of the cam to follow.

15. Valve drive according to claim 14, characterized in that the tappet (1 a) on its the cam follower (10) facing side has a circular arc-like recess and the cam follower (10) has a corresponding rounding to allow a relative movement ,