DE102015214115A1 - Hubvariabler valve drive for an internal combustion engine - Google Patents

Abstract

Hubvariabler valve drive for an internal combustion engine with an intermediate lever, which is mounted on the one hand sliding on a slide track a backdrop and on the other hand has a working curve, wherein the working curve via an intermediate element with a gas exchange valve is in operative connection, wherein a first adjusting device for pivoting the intermediate lever to a near-stage point is provided against a spring force of a spring element, wherein the intermediate lever is displaceable with a second adjusting device along the slide track, wherein the second adjusting device has a first adjustment range for a zero stroke, a second adjustment range for a partial stroke and a third adjustment range for a full stroke of the gas exchange valve, wherein the second adjusting device is an eccentric of an eccentric shaft with a depositing area in the second setting area. The proposed design of the eccentric results in a reliable, maximum valve acceleration where it is functionally appropriate.

Description

The invention relates to a variable-stroke valve drive for an internal combustion engine having the features of the preamble of patent claim 1.

For technical environment is for example on the European patent specification EP 1 387 928 B1 pointed. For this, a valve drive device for variable stroke adjustment of a gas exchange valve of an internal combustion engine is known in which the gas exchange valve with the interposition of a transmission element with a movable about a rotation axis roller and a Leerhubkurve and a lift curve comprehensive control path in an end portion of a stroke of the gas exchange valve of a camshaft controlled pivot lever, wherein the spring-loaded via a cam track associated with the cam pivot lever is supported on the other hand for variable stroke adjustment via a controlled by means of an adjustment position variable and fixable swing fulcrum along a circular path. The valve drive device is characterized in that arranged on a housing part of the internal combustion engine circular path serves as a backdrop with a radius about the axis of rotation of the roller of the transmission element of the controlled positionally variable support of the pivot lever, wherein the control track of the pivot lever in the transition region between Leerhubkurve and lift curve with a on a Valve clearance is formed parked in the valve drive device parked ramp.

• – einem Zwischenhebel, der einerseits schiebebeweglich auf einer Kulissenbahn einer Kulisse gelagert ist und andererseits eine Arbeitskurve aufweist, wobei
• – die Arbeitskurve über ein Zwischenelement mit einem Gaswechselventil in Wirkverbindung steht, wobei
• – eine erste Stellvorrichtung zum Drehen des Zwischenhebels um einen kulissennahen Punkt gegen eine Federkraft eines Federelements vorgesehen ist, wobei
• – der Zwischenhebel mit einer zweiten Stellvorrichtung entlang der Kulissenbahn verschiebbar ist, wobei
• – die zweite Stellvorrichtung einen ersten Einstellpunkt für einen Nullhub, zumindest einen zweiten Einstellpunkt für einen Teilhub und zumindest einen dritten Einstellpunkt für einen Vollhub des Gaswechselventils aufweist, wobei
• – dem Gaswechselventil des ersten Zylinders eine erste zweite Stellvorrichtung und dem Gaswechselventil des zweiten Zylinder eine zweite zweite Stellvorrichtung zugeordnet ist.

Next is from the German patent application DE 10 2006 033 559 A1 a variable-stroke valve train for an internal combustion engine known, with at least a first and a second cylinder with the same gas exchange valves, each cylinder is associated with a gas exchange valve actuator, consisting of at least

• - An intermediate lever, which is mounted on the one hand sliding on a slide track a backdrop and on the other hand has a working curve, said
• - The working curve is connected via an intermediate element with a gas exchange valve in operative connection, said
• - Is provided a first adjusting device for rotating the intermediate lever to a near-point point against a spring force of a spring element, wherein
• - The intermediate lever is displaceable with a second adjusting device along the slide track, wherein
• - The second adjusting device has a first set point for a zero stroke, at least a second set point for a partial lift and at least a third set point for a full lift of the gas exchange valve, wherein
• - The gas exchange valve of the first cylinder, a first second adjusting device and the gas exchange valve of the second cylinder is associated with a second second adjusting device.

It is located at the upper end (at maximum Gaswechselventilhub) of the second adjustment, which is usually designed as an eccentric, a deposition area in which the Gaswechselventilhub with further rotation of the eccentric towards larger Gaswechselventilhub not further increases (or even slightly depending on the mechanical design can decrease), ie in this position the restoring moment of the intermediate lever roller resting there disappears on the eccentric shaft (or pushes it against the stop at the maximum eccentric angle, see 2 ). This is the so-called "emergency mode", ie in case of failure of the servomotor of the eccentric shaft of the valve gear remains at maximum stroke (maximum Gaswechselventilhub) and the internal combustion engine can be operated by means of the throttle (with a disadvantage in fuel consumption) at all loads and speeds.

If you want to operate the internal combustion engine with a combustion process in which a reduced Gaswechselventilhub applied in the range of maximum power (Miller method), one does not fully exploits the dynamics of the valve train, as well as the maximum Gaswechselventilhub at maximum speed due to the above-described emergency operation strategy possible have to be.

The Miller internal combustion engine is named after Miller internal combustion engine, in which the fuel is introduced during the intake into the intake air, resulting in an ignitable mixture in the cylinder as in the gasoline engine. In contrast to the gasoline engine, a Miller internal combustion engine is characterized by a fifth step. Therefore, the Miller internal combustion engine is also referred to as "five-stroke". The intake valve is already closed during the intake stroke, resulting in an incomplete combustion chamber filling result. The previously closed gas exchange inlet valve prevents or reduces the so-called knocking.

For example, an exhaust gas turbocharger, which supplies the cylinders with additional fuel-air mixture, compensates for losses and less power compared to conventional internal combustion engines. The result of these changes are lower exhaust gas temperature, fewer pollutants, low tendency to knock and high efficiency of the internal combustion engine. Other benefits include lower heat output and reduction of nitrogen oxide output, as well as greater performance lower fuel consumption with relatively less displacement.

The object of the present invention is to avoid the above-mentioned disadvantage, for example for the Miller combustion process.

This object is achieved by the feature in the characterizing part of patent claim 1.

According to the invention, an eccentric contour with a depositing area located within the adjustment range is proposed for the second adjusting device. This can z. B. at a Gaswechselventilhub, as in 2 represented, for example, at about 6.5 mm, which is driven at maximum speed. Since the gas exchange valve acceleration increases with increasing Gaswechselventilhub and the valve train design for the maximum speed is necessary only for this reduced and thus emergency-safe Gaswechselventilhub, this can be made shorter and thus richer, which accommodates the desired function. Next Gaswechselventilhübe can be made more freely above the deposit area in an advantageous manner and can there also use higher accelerations, since they do not have to be suitable for the maximum speeds.

• – Vorteile bei RDE (Real Driving Emissions) tauglichen Brennverfahren, wie dem Miller-Brennverfahren,
• – Erschließen der Potenziale in nicht notwendig notlauftauglichen Gaswechselventilhubbereichen,
• – Kraftstoffverbrauchs- und Emissionsvorteile.

The inventive design of the variable-stroke valve drive advantageously results in a reliable maximum gas exchange valve acceleration where it is functionally appropriate:

• - Advantages of RDE (Real Driving Emissions) suitable combustion processes, such as the Miller combustion process,
• - unlocking the potentials in gas emergency valve lifting areas that are not necessarily suitable for emergency
• - Fuel consumption and emission benefits.

The embodiment according to claim 2 is a preferred embodiment, in which the depositing area forms a quasi "Kuhle", d. H. The torque exerted on the eccentric shaft disappears in this position of the eccentric shaft.

In the following the invention is explained in more detail with reference to two figures.

1 shows a section through a variable-stroke valve drive according to the invention.

2 shows a survey curve for a standard eccentric and a survey curve for an eccentric according to the invention.

1 shows a section through a variable-stroke valve drive according to the invention 1 for an internal combustion engine, not shown. The arranged in a cylinder head stroke variable valve train 1 consists essentially of an intermediate lever 2 , on the one hand with a roller element, rollable on a slide track 3 ' a backdrop 3 is stored and on the other hand, a working curve 4 which is divided into a Teilhubkurve and Vollhubkurve, wherein the working curve 4 via an intermediate element 5 , a roller rocker arm, with a gas exchange valve 6 is in active connection.

Furthermore, a first adjusting device 7 , a camshaft, for rotating the intermediate lever 2 around a point close to the stage 8th , a center of rotation of the on the backdrop 3 supported roller element, against a spring force of a spring element 9 intended. The intermediate lever 2 is with a second actuator 10 , a cam or eccentric disc, along the slide track 3 ' on the on the slide railway 3 ' supported roller element displaceable.

According to the invention, the second adjusting device 10 an eccentric of an eccentric shaft with a first 11 , a second 12 and a third adjustment range 13 with a depositing area in the second setting range 12 , Preferably, the depositing area is a section-wise radius reduction of the eccentric contour.

Thus, an eccentric contour is proposed with a lying within the adjustment range depositing area. This can z. B. at the Gaswechselventilhub, which is set at the maximum speed.

2 shows in a diagram a Gaswechselventilhub from 0 to 10 mm on a Y-axis over an eccentric angle φ in ° on an X-axis. A graph 15 shows the Gaswechselventilhub on the eccentric angle for a standard eccentric. In contrast, a second graph shows 16 the valve lift over the eccentric angle for an eccentric according to the invention, wherein the depositing area at a Gaswechselventilhub is about 6.5 mm.

Since the gas exchange valve acceleration increases with increasing valve lift and the design of the valve train for the maximum speed is only necessary for this reduced stroke, this can be made shorter and thus fuller, which accommodates the desired function. Gas exchange valve lifts above the deposit area can be designed more freely there due to the reduced speed requirement and can also allow higher accelerations there.

• – Vorteile bei RDE (Real Driving Emissions) tauglichen Brennverfahren, wie dem Miller-Brennverfahren,
• – Erschließen der Potenziale in nicht notwendig notlauftauglichen Gaswechselventilhubbereichen,
• – Kraftstoffverbrauchs- und Emissionsvorteile.

Due to the inventive design of the variable-stroke valve drive advantageously results in a reliable maximum Gas exchange valve acceleration where it is functionally appropriate:

• - Advantages of RDE (Real Driving Emissions) suitable combustion processes, such as the Miller combustion process,
• - unlocking the potentials in gas emergency valve lifting areas that are not necessarily suitable for emergency
• - Fuel consumption and emission benefits.

LIST OF REFERENCE NUMBERS

1

Hubvariabler valve drive

2

intermediate lever

3

scenery

3 '

link path

4

working curve

5

intermediate element

6

Gas exchange valve

7

first adjusting device

8th

scene near the point

9

spring element

10

second adjusting device

11

first setting range

12

second setting range

13

third setting range

14

cylinder head

15

Standardexzenter

16

eccentric according to the invention

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• EP 1387928 B1 [0002]
• DE 102006033559 A1 [0003]

Claims (2)

Hubvariabler valve drive ( 1 ) for an internal combustion engine with - an intermediate lever ( 2 ), on the one hand sliding on a slide track ( 3 ' ) a backdrop ( 3 ) and on the other hand a working curve ( 4 ), wherein - the working curve ( 4 ) via an intermediate element ( 5 ) with a gas exchange valve ( 6 ) is in operative connection, wherein - a first adjusting device ( 7 ) for pivoting the intermediate lever ( 2 ) around a near-kinetic point ( 8th ) against a spring force of a spring element ( 9 ), wherein - the intermediate lever ( 2 ) with a second adjusting device ( 10 ) along the slide track ( 3 ' ) is displaceable, wherein - the second adjusting device ( 10 ) a first adjustment range ( 11 ) for a zero stroke, a second adjustment range ( 12 ) for a partial lift and a third adjustment range ( 13 ) for a full lift of the gas exchange valve ( 6 ), characterized in that, the second actuating device ( 10 ) is an eccentric of an eccentric shaft having a deposition area in the second adjustment area. Hubvariabler valve drive according to claim 2, characterized in that the depositing area is a partial reduction of an eccentric outer contour.

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