DE102020101555A1 - Stroke variable valve train with a double leg spring - Google Patents

Abstract

Stroke-variable valve drive with a double leg spring in a cylinder head of an internal combustion engine, wherein the valve drive comprises a pivot lever which is supported on the one hand with a roller element with a pivot point on a slide track and on the other hand with a control track on an intermediate element to a gas exchange valve without play, the pivot lever for Stroke adjustment between the support points on the one hand swiveling controlled by a cam of a camshaft against a force of the double leg spring and on the other hand the pivot point is controlled by an adjusting device for stroke height adjustment parallel to the slide track, the double leg spring in its middle area forms an intermediate leg with a reversal of the direction of rotation of the two spring legs and where the double leg spring can be mounted in the area of the intermediate leg, the ends of the spring legs largely being parallel to a longitudinal axis of the double leg Elschelfeder are reshaped.Due to the design according to the invention, an enlarged stroke adjustment range for the gas exchange valve is shown, with simplified assembly.

Description

The invention relates to a stroke-variable valve drive with a double leg spring in a cylinder head of an internal combustion engine with the features from the preamble of claim 1.

A generic double leg spring for a variable lift valve drive in a cylinder head of an internal combustion engine is, for example, from the German Offenlegungsschrift DE 101 22 152 A1 famous. In this laid-open specification, an assembly aid for a double leg spring for a stroke-variable valve drive in a cylinder head of an internal combustion engine is described, the double leg spring consisting of at least a first and a second leg spring, which are arranged largely coaxially to a common spring axis, and the first leg spring is shown a first The spring leg and the second leg spring have a second spring leg, the winding directions of the first and second leg springs being opposite and the first and second leg springs forming a common intermediate leg in the area of the reversal of the winding direction, which can be connected to a section of the cylinder head, whereby the assembly aid the first and the second spring leg releasably connects to one another with the intermediate leg in a pretensioned operative position. The assembly aid enables the double leg spring to be assembled without risk and without problems in a stroke-variable valve drive in a cylinder head of an internal combustion engine.

• 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 Federelementes 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 einen dritten Einstellpunkt für einen Vollhub des Gaswechselventils aufweist und wobei dem Gaswechselventil des ersten Zylinders eine erste zweite Stellvorrichtung und dem Gaswechselventil des zweiten Zylinders eine zweite zweite Stellvorrichtung zugeordnet ist.

From the DE 10 2006 033 559 A1 a variable-stroke valve drive for an internal combustion engine is known. The stroke-variable valve drive for an internal combustion engine has at least a first and a second cylinder and gas exchange valves with the same effect, a gas exchange valve actuation unit being assigned to each cylinder. This gas exchange valve actuation unit consists of at least:

• An intermediate lever which on the one hand is slidably mounted on a slide track of a gate and on the other hand has a working curve, the working curve being in operative connection with a gas exchange valve via an intermediate element, a first adjusting device being provided for rotating the intermediate lever around a point near the gate against a spring force of a spring element is, wherein the intermediate lever can be displaced with a second adjusting device along the slide track, the second adjusting device having a first setting point for a zero stroke, at least one second setting point for a partial stroke and a third setting point for a full stroke of the gas exchange valve and the gas exchange valve of the first cylinder a first second adjusting device and a second second adjusting device is assigned to the gas exchange valve of the second cylinder.

Next is from the European patent specification EP 2 568 132 B1 , from which the present invention is based, a stroke-variable valve drive with a double leg spring in a cylinder head of an internal combustion engine is known. The valve drive comprises a swivel lever, which is supported on the one hand with a roller element with a swing pivot point on a link path of a gate and on the other hand with a control path on an intermediate element to a gas exchange valve without play. To adjust the stroke between the support points, the pivot lever can be pivoted, controlled by a cam of a camshaft against a force of the double leg spring, on the one hand, and the pivot point can be moved in a controlled manner by an adjustment device for the stroke height adjustment parallel to the slide track.The double leg spring forms an intermediate leg in its middle area with a reversal of the direction of rotation of the two Spring leg, whereby the double leg spring can be mounted in the area of the intermediate leg.

The latter EP patent thus describes a variable-lift valve drive with a double leg spring design with spring legs with an S-flap, the spring legs engaging the contact surface on the pivot lever from "above" and must be inserted into the lateral guide tabs of the pivot lever during assembly from the "rear".

1. 1. Durch den S-Schlag der Federschenkel ist der Drehwinkel der Exzenterwelle, dem Verstellelement, geometrisch auf 254° beschränkt, da sonst der Federschenkel mit dem Exzenter der Exzenterwelle kollidiert.
2. 2. Durch eine Fehlmontage kann ein oder beide Schenkel der Federschenkel unter Umständen nicht richtig auf die Anlagefläche des Schwenkhebels eingeführt werden, sondern seitlich auf den Stirnflächen der seitlichen Führungslaschen aufliegen. Beim ersten Durchdrehen der Nockenwelle und somit einer Schwenkbewegung des Zwischenhebels rutscht der Federschenkel seitlich vom Zwischenhebel herunter und schleift dann auf der Nockenwelle. Die variable Hubfunktion des hubvariablen Ventiltriebs ist damit nicht mehr gewährleistet. Dies führt zu einem Verschleiß des Nockenwellen-Rohres durch den Federschenkel und es kann zu einem Bruch der Nockenwelle kommen.

The following problems arise here:

1. 1. The angle of rotation of the eccentric shaft, the adjusting element, is geometrically limited to 254 ° due to the S-stroke of the spring legs, since otherwise the spring leg collides with the eccentric of the eccentric shaft.
2. 2. As a result of incorrect assembly, one or both legs of the spring legs may not be correctly inserted onto the contact surface of the pivot lever, but lie laterally on the end faces of the lateral guide tabs. When the camshaft is rotated for the first time and thus the intermediate lever is pivoted, the spring leg slides sideways down from the intermediate lever and then grinds on the camshaft. The variable lift function of the variable lift valve drive is therefore no longer guaranteed. This leads to wear of the camshaft tube due to the spring leg and the camshaft can break.

The object of the present invention is to avoid the problems mentioned above.

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

According to the invention, the contact of the spring legs of the double leg spring is modified from a vertical arrangement (S-stroke) to a horizontal arrangement.

1. 1. Durch die erfindungsgemäße Ausgestaltung wird der Abstand des Federschenkels im Bereich des Zwischenhebels zum Exzenter, dem Verstellelement, deutlich vergrößert und damit ist eine Vergrößerung des Drehwinkels der Exzenterwelle möglich (bis zu 300°). Damit steht ein größerer Verstellwinkel zur Auslegung der Hubfunktion des hubvariablen Ventiltriebs zur Verfügung. Somit kann, ohne eine Vergrößerung des Verstellmoments des hubvariablen Ventiltriebs (dann wäre ein stärkerer Verstellmotor nötig) ein größerer Exzenterhub realisiert werden.
2. 2. Weiter führt die erfindungsgemäße Ausgestaltung zu einer Verbesserung der Montage. Der L-förmige Federschenkel der Doppelschenkelfeder muss nur auf die korrespondierende Auflagefläche des Zwischenhebels aufgelegt werden. In vorteilhafter Weise ist kein zusätzliches Positionieren des Federschenkels notwendig und damit ist keine Fehlmontage möglich.

This has the following advantages:

1. 1. The configuration according to the invention significantly increases the distance between the spring leg in the area of the intermediate lever and the eccentric, the adjusting element, and thus an increase in the angle of rotation of the eccentric shaft is possible (up to 300 °). This means that a larger adjustment angle is available for designing the stroke function of the stroke-variable valve drive. In this way, a larger eccentric stroke can be realized without increasing the adjusting torque of the stroke-variable valve drive (then a more powerful adjusting motor would be necessary).
2. 2. The configuration according to the invention also leads to an improvement in assembly. The L-shaped spring leg of the double leg spring only needs to be placed on the corresponding support surface of the intermediate lever. Advantageously, no additional positioning of the spring leg is necessary and therefore no incorrect assembly is possible.

Advantageous further developments of the invention are described in the subclaims.

• 1 zeigt eine Aufsicht auf einen Abschnitt eines gattungsgemäßen hubvariablen Ventiltriebs gemäß dem Stand der Technik.
• 2 zeigt eine Seitenansicht eines hubvariablen Ventiltriebs gemäß der Erfindung im Vergleich zum Stand der Technik.
• 3 zeigt eine Aufsicht auf den hubvariablen Ventiltrieb gemäß der Erfindung im Vergleich zum Stand der Technik.

In the following, the invention is explained in more detail in one figure based on the prior art and in two figures on the basis of an embodiment according to the invention in comparison with the prior art.

• 1 shows a plan view of a section of a generic stroke-variable valve drive according to the prior art.
• 2 shows a side view of a variable-lift valve drive according to the invention in comparison with the prior art.
• 3 shows a plan view of the variable-lift valve drive according to the invention in comparison with the prior art.

In the following, the 1 until 3 the same reference numbers for the same components.

1 shows a plan view of a section of a generic stroke-variable valve drive 1 with a double leg spring 2 according to the state of the art. The section is for two gas exchange valves 9 provided, with only one gas exchange valve 9 is numbered. This valve train 1 can be installed in a cylinder head (not shown) of an internal combustion engine and is from the prior art, the DE 10 2006 033 559 A1 , famous.

The valve train 1 includes a pivot lever 3 , on the one hand with a roller element 4th with a swing pivot point on a slide track 5 a backdrop 6th and on the other hand with a control track 7th on an intermediate element 8th , a roller rocker arm, on a gas exchange valve 9 is supported free of play. The intermediate element is used for play-free support 8th opposite the gas exchange valve 9 on a lash adjuster 13th , preferably a hydraulic lash adjuster 13th , supported. The swivel lever is used to adjust the stroke 3 between the support points on the one hand by a not shown cam of a camshaft against a force of the double leg spring 2 controlled pivotable and on the other hand the pivot point of an adjusting device 10 , an eccentric shaft, for height adjustment parallel to the slide track 5 can be moved in a controlled manner. Further forms the double leg spring 2 an intermediate leg in its middle area 11 , with a reversal of the direction of rotation of the two spring legs 2a , 2 B (2b is not numbered because it cannot be seen), with the intermediate leg 11 is encased by a mounting plate. With a mounting means is the double leg spring 1 attachable either to the cylinder head or to a shaft bearing, not shown. How the variable-stroke valve train works 1 will also apply to international patent applications WO 02/092972 A1 pointed out.

As already shown, the known double leg spring design has spring legs 2a , 2 B with an S-beat, the spring legs 2a , 2 B from "above" to the contact surfaces on the swivel lever 3 intervene and when assembling from the "rear" in the lateral, non-numbered guide tabs of the swivel lever 3 to be introduced.

2 shows a side view of a variable-lift valve drive 1 according to the invention compared to the prior art. for 2 the same applies as for 1 . The spring leg at the bottom in the drawing 2a corresponds to the design according to the prior art, the spring leg at the top in the drawing 2 B corresponds to the embodiment according to the invention. In this comparison, the end of the spring leg is according to the invention 2 B largely parallel to a longitudinal axis 12th the double leg spring 2 reshaped.

In the present exemplary embodiment, the spring leg is 2 B reshaped inwards. In In a further exemplary embodiment, the spring leg 2 B also be reshaped to the outside.

Next is the spring leg in the present embodiment 2 B formed by approx. 90 °, whereby larger or smaller forming angles are also possible.

For the best possible support of the spring leg 2 B indicates the pivot lever 3 for each end of the spring legs according to the invention 2a , 2 B a corresponding support surface 13th on.

3 shows a plan view of the variable-lift valve train 1 according to the invention compared to the prior art. It is the same as to 2 said. Finally, it should be said that compared to the 2 and 3 in reality both spring legs 2a , 2 B the double leg spring 2 have the L-shape and the pivot lever 3 for every spring leg 2a , 2 B a support surface 13th having.

1. 1. Es wird der Abstand des Federschenkels 2b im Bereich des Zwischenhebels 3 zum Exzenter, dem Verstellelement 10, deutlich vergrößert und damit ist eine Vergrößerung des Drehwinkels der Exzenterwelle möglich (bis zu 300°). Damit steht ein größerer Verstellwinkel zur Auslegung der Hubfunktion des hubvariablen Ventiltriebs 1 zur Verfügung. Somit kann, ohne eine Vergrößerung des Verstellmoments des hubvariablen Ventiltriebs 1 ein größerer Exzenterhub realisiert werden.
2. 2. Weiter führt die erfindungsgemäße Ausgestaltung zu einer Verbesserung der Montage. Der L-förmige Federschenkel 2b der Doppelschenkelfeder 2 muss nur auf die korrespondierende Auflagefläche 13 des Zwischenhebels 3 aufgelegt werden. In vorteilhafter Weise ist kein zusätzliches Positionieren des Federschenkels 2b notwendig und damit ist keine Fehlmontage möglich.

The design according to the invention results in the following advantages:

1. 1. It becomes the distance of the spring leg 2 B in the area of the intermediate lever 3 to the eccentric, the adjusting element 10 , significantly enlarged and thus an increase in the angle of rotation of the eccentric shaft is possible (up to 300 °). This means that there is a larger adjustment angle for the design of the lift function of the lift-variable valve drive 1 to disposal. Thus, without increasing the adjusting torque of the variable-lift valve drive 1 a larger eccentric stroke can be realized.
2. 2. The configuration according to the invention also leads to an improvement in assembly. The L-shaped spring leg 2 B the double leg spring 2 only needs to be placed on the corresponding support surface 13th of the intermediate lever 3 be put on. Advantageously, there is no additional positioning of the spring leg 2 B necessary and therefore no incorrect assembly is possible.

List of reference symbols

1.

Valve train

2.

Double leg spring

2a

State-of-the-art spring legs

2 B

Spring legs according to the invention

3.

Swivel lever

4th

Role element

5.

Slide track

6th

Backdrop

7th

Control track

8th.

Intermediate element

9.

Gas exchange valve

10.

Adjusting device

11.

Intermediate thighs

12th

Longitudinal axis

13th

Support surface

14th

Lash adjuster

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 10122152 A1 [0002]
• DE 102006033559 A1 [0003, 0014]
• EP 2568132 B1 [0004]
• WO 02/092972 A1 [0015]

Claims (4)

Stroke-variable valve drive (1) with a double leg spring (2) in a cylinder head of an internal combustion engine, the valve drive (1) comprising a pivoting lever (3) which, on the one hand, is connected to a roller element (4) with a pivot point on a slide track (5) of a gate ( 6) and on the other hand with a control path (7) on an intermediate element (8) to a gas exchange valve (9) is supported without play, the pivot lever (3) for stroke adjustment between the support points on the one hand by a cam of a camshaft against a force of the double leg spring (2 ) can be pivoted in a controlled manner and, on the other hand, the pivot point can be moved in a controlled manner by an adjusting device (10) for adjusting the stroke height parallel to the slide track (5), the double leg spring (2) forming an intermediate leg (11) in its middle area with a reversal of the direction of rotation of the two spring legs (2a, 2b) ) and wherein the double leg spring (2) can be mounted in the area of the intermediate leg (11) t, characterized in that the ends of the spring legs (2a, 2b) are shaped largely parallel to a longitudinal axis (12) of the double leg spring (2). Variable stroke valve train according to Claim 1 , characterized in that the ends of the spring legs (2a, 2b) are shaped inwards or outwards. Variable stroke valve train according to Claim 1 or 2 , characterized in that the ends of the spring legs (2a, 2b) are deformed by approx. 90 °. Stroke variable valve train according to one of the Claims 1 until 3 , characterized in that the pivot lever (3) has a corresponding support surface (13) for each end of the spring legs (2a, 2b).

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