EP3824165B1 - Variable valve drive device - Google Patents

Variable valve drive device Download PDF

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Publication number
EP3824165B1
EP3824165B1 EP19745032.3A EP19745032A EP3824165B1 EP 3824165 B1 EP3824165 B1 EP 3824165B1 EP 19745032 A EP19745032 A EP 19745032A EP 3824165 B1 EP3824165 B1 EP 3824165B1
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EP
European Patent Office
Prior art keywords
camshaft
cam element
drive device
valve drive
ramp surface
Prior art date
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Application number
EP19745032.3A
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German (de)
French (fr)
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EP3824165A1 (en
Inventor
David LEKANIC
Martin ZINTERL
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AVL List GmbH
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AVL List GmbH
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Publication of EP3824165A1 publication Critical patent/EP3824165A1/en
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/02—Valve drive
    • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
    • F01L1/047—Camshafts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/02—Valve drive
    • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
    • F01L1/047—Camshafts
    • F01L1/053—Camshafts overhead type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/02—Valve drive
    • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
    • F01L1/08—Shape of cams
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
    • F01L13/0015—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque
    • F01L13/0036—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque the valves being driven by two or more cams with different shape, size or timing or a single cam profiled in axial and radial direction
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
    • F01L13/0015—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque
    • F01L13/0057—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque by splittable or deformable cams
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/12—Transmitting gear between valve drive and valve
    • F01L1/18—Rocking arms or levers
    • F01L1/181—Centre pivot rocking arms
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/02—Valve drive
    • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
    • F01L1/047—Camshafts
    • F01L2001/0471—Assembled camshafts
    • F01L2001/0473—Composite camshafts, e.g. with cams or cam sleeve being able to move relative to the inner camshaft or a cam adjusting rod
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L2250/00—Camshaft drives characterised by their transmission means
    • F01L2250/02—Camshaft drives characterised by their transmission means the camshaft being driven by chains
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L2305/00—Valve arrangements comprising rollers

Definitions

  • the invention relates to a variable valve drive device for actuating at least one gas exchange valve of an internal combustion engine, with a camshaft that is mounted such that it can rotate about an axis of rotation and has at least one cam element that can be adjusted via an adjusting device, the cam element being mounted pivotably about a pivot axis between at least a folded-in first position and a folded-out second position which runs parallel to the axis of rotation and is arranged on the camshaft at a first distance from it, and wherein the adjustable cam element is arranged adjacent in the direction of the axis of rotation of the camshaft to at least one base cam rigidly connected to the camshaft, the adjusting device having at least one inside the camshaft between at least a first thrust position and a second thrust position displaceably arranged push rod, wherein the push rod at least one preferably parallel to the axis of rotation se of the camshaft has a stop surface for the cam element and at least one inclined to the axis of rotation of the camshaft ramp surface, where
  • valve train devices of internal combustion engines depending on the operating state. At low loads, it is advantageous if the valve lift is less than at high loads, so as not to adversely affect the combustion processes in the individual cylinders. At the same time, there is a need to be able to vary the valve lift curve to affect the opening and closing of the intake and exhaust valves.
  • Various solutions for variable valve drives are therefore known in the prior art in order to provide appropriate options for influencing.
  • the WO 95/16852 A1 describes a solution for using a push rod that can be displaced axially in a hollow camshaft in order to extend a cam element from a first position to a second position in order to vary the valve lift curve.
  • the push rod has a ramp on its lateral surface which acts on a ball which is arranged in a radial bore of the camshaft and which contacts an inner surface of the rotatably mounted cam element.
  • the ball is moved in the radial bore and the cam element is thus pivoted from a first position into a second position.
  • the EP 3 045 690 A2 describes a variable valve actuation device with a camshaft on which are arranged pivotable cam elements between two positions.
  • Each pivotable cam element is actuated via a piston element which is mounted within the camshaft so that it can be displaced in the direction of the axis of rotation of the camshaft and which can be deflected hydraulically against a return spring in a guide sleeve arranged within the camshaft.
  • the piston element has a ramp on the lateral surface, which interacts with a retaining pin that can be displaced transversely to the piston element in a radial bore of the camshaft.
  • the ramp pushes the retaining pin outwards in the radial bore of the camshaft, the retaining pin pressing the cam element into its pivoted-out second position and holding it in this position.
  • the piston element In the depressurized state, the piston element is pushed into the rest position by the restoring spring, in which the retaining pin is released and the cam element can thus be pivoted into its first position.
  • the cam element In the extended, second position, the cam element can be fixed via a fixing device.
  • the fixing device has at least one locking pin that can be actuated hydraulically against a return spring, which is displaceably mounted in a guide cylinder arranged eccentrically in the camshaft and, in a locking position, engages in a pin hole of the cam element.
  • a disadvantage is the large number of components and contact surfaces, especially in the power flow between the piston part and the cam part, which have an unfavorable effect on the overall tolerance and the actuation play.
  • a cam element which is mounted pivotably in the camshaft, by means of a push rod which is displaceably arranged in the camshaft.
  • the push rod has a relatively flat ramp surface, which is formed by the casing of a frustoconical section of the push rod.
  • the cam element is rotatably mounted in an area of the cam which area has the highest cam elevation. As a result, only one flank of the elevation curve, but not the entire elevation curve, can be changed by extending the cam element. In particular, the maximum stroke cannot be influenced.
  • the ramp is formed by a frusto-conical portion of the push rod.
  • the cam element can be displaced at most only by half the diameter of the push rod, with the ramp surface acting on a lateral edge of the cam element.
  • a counter ramp surface on the cam element is not provided - therefore, incorrect actuation and jamming can occur, which has a negative effect on operational safety.
  • this known valve drive device is relatively susceptible to wear.
  • the DE 10 2016 103 233 A1 discloses a variable valve actuation device in which at least one cam member is pivotally supported on the camshaft between a first position and a second position, with a resilient member acting on the cam member toward the extended second position.
  • the cam element can be fixed via a fixing device.
  • the fixing device has at least one locking pin that can be actuated hydraulically against a return spring, which is displaceably mounted in a guide cylinder arranged eccentrically in the camshaft and, in a locking position, engages in a pin hole of the cam element.
  • the cam element is connected to a drive element which cooperates with a pressing part. The cam element can be moved back into the first position by the pressing part via the drive element.
  • the JP 2016 200053 A shows a similar valve actuation device.
  • a disadvantage of the known solutions is that existing valve lifting curves can only be influenced but not changed by the pivotable cam elements.
  • the mechanisms for rotating the cam elements are consistently complex and prone to wear and failure.
  • the object is achieved according to the invention in that the cam element has a counter-ramp surface which interacts with the ramp surface of the push rod and is designed at least partially inclined to the axis of rotation of the camshaft.
  • the cam element can be contacted directly with the push rod in at least one push position, so that the push rod acts directly on the cam element.
  • the push rod acts directly on the cam element.
  • This has the advantage that the overall tolerance and the actuation play can be kept small.
  • the lower Number of point or area contacts reduces the wear of the device.
  • the ramp surface is arranged on a front side of the push rod, with the ramp surface preferably extending over the entire front surface of the front side.
  • a variant embodiment of the invention provides that the ramp surface has at least two areas with different angles of inclination in relation to the axis of rotation of the camshaft.
  • the ramp surface is preferably spatially curved at least in sections and is preferably formed by a surface of revolution.
  • the ramp surface is formed by a conical surface.
  • the ramp surface is thus preferably formed by a surface which is produced by rotating a line, for example a straight line, about an axis.
  • the counter-ramp surface of the cam element is advantageously spatially curved, at least in sections.
  • the counter-ramp surface is formed by a surface of revolution, in particular a conical surface.
  • the counter-ramp surface of the cam element has at least two sections with different angles of inclination with respect to the axis of rotation of the camshaft.
  • the ramp surface and/or the counter-ramp surface is/are inclined at least in sections at an angle of inclination of between approximately 30° and 60° to the axis of rotation of the camshaft. This makes it possible that, if the adjustment is incomplete, the cam element pushes the push rod back into the rest position and the cam element resumes the pivoted-in first position. A self-locking between the ramp surface and the counter-ramp surface can be largely avoided.
  • the cam element has a counter-stop surface which interacts with the stop surface of the push rod and is preferably of cylindrical design.
  • the counter-stop surface is preferably arranged axially adjacent to the counter-ramp surface--in relation to the axis of rotation of the camshaft. It is advantageous if the counter-ramp surface is designed as a chamfer around the counter-stop surface in the cam element.
  • the counter-ramp surface of the cam element abuts the ramp surface of the push rod.
  • the counter-abutment surface of the cam element lies against the abutment surface of the connecting rod.
  • the cam element is prestressed in the direction of the first position by a restoring element, which is preferably formed by a torsion spring.
  • the cam element is thus pressed into its folded-in first position by the restoring element.
  • the cam element is pressed against the restoring force of the restoring element by means of the ramp surface of the push rod into the unfolded second position.
  • At least one limiting element is provided which is fixedly connected to the camshaft, the cam element having a limiting surface which corresponds to the limiting element, the limiting surface of the cam element bearing against the limiting element when the cam element is in a maximum swiveling-out position.
  • the delimiting element is designed, for example, as a delimiting pin. The limiting element limits the outward deflection movement of the cam element. This can prevent early signs of wear and damage.
  • the cam element in the second position completely covers the contour of at least one base cam, preferably two base cams axially adjoining the cam element on both sides, viewed in the direction of the axis of rotation of the camshaft .
  • the valve-actuating device 1 has a camshaft 2 that is rotatably mounted about an axis of rotation 2a and has at least one cam element 3 that can be adjusted via an adjusting device 20 .
  • the cam element 3 is between a folded first position A ( 4 ) and an unfolded second position B ( figure 5 ) pivoted about a pivot axis 3a.
  • This pivot axis 3a is aligned parallel to the axis of rotation 2a of the camshaft 2 and is arranged on the camshaft 2 at a first distance a therefrom.
  • the cam element 3 is mounted pivotably in the camshaft 2 , the pivot axis 3a of the cam element 3 running parallel to and at a first distance a from the axis of rotation 2a of the camshaft 2 .
  • the adjustable cam element 3 is arranged adjacent to two base cams 4a, 4b of a cam body 4 in the direction of the axis of rotation 2a of the camshaft 2 .
  • the cam body 4 has a receptacle 5 in which the cam element 3 is predominantly accommodated and into which the cam element 3 can be pivoted.
  • Reference numeral 21 designates a cam follower element, for example a rocker arm, which rests against base cam 4a, 4b or cam element 3 via a roller 22 and is deflected according to the cam contour of base cam 4a, 4b or cam element 3.
  • the cam follower element 21 acts on at least one gas exchange valve (not shown) of the internal combustion engine and controls its stroke.
  • Adjusting device 20 has at least one push rod 6 with a substantially cylindrical shape that is slidably disposed within camshaft 2, wherein push rod 6 can be displaced axially—i.e., parallel to axis of rotation 2a of camshaft 2—between a first thrust position A1 and a second thrust position B1.
  • the first thrust position A1 corresponds to the first position A of the cam element 3.
  • the second thrust position B1 corresponds to the second position B of the cam element 3.
  • the push rod 6 is cylindrical in the exemplary embodiment, but a prismatic or other shape is also possible.
  • the connecting rod 6 has the same axis as the camshaft 2 arranged - the longitudinal axis 6a of the push rod 6 thus coincides with the axis of rotation 2a of the camshaft 2 together.
  • the push rod 6 has a stop surface 7 for the cam element 3 which is parallel to the axis of rotation 2a of the camshaft 2 .
  • the stop surface 7 is formed by the cylindrical outer surface of the push rod 6 and serves as a stop for the cam element 3 in the unfolded second position. The stop surface 7 thus prevents the pivoted-out cam element 3 from pivoting back from the second position B into the first position A
  • the push rod 6 has a ramp surface 8 that is inclined to the axis of rotation 2a of the camshaft 2 .
  • the ramp surface 8 serves to transfer the axial movement of the push rod 6 into a radial pivoting movement of the cam element 3 and to move the cam element 3 from the first position A to the second position B.
  • the ramp surface 8 is arranged on a first end face 9 of the push rod 6 .
  • the displacement of the push rod 6 takes place via a reference number 11 in 1 , 4 and 5 indicated actuator - for example, hydraulically, pneumatically, electrically, electromagnetically or otherwise actuatable - which acts, for example, on one of the first end face 9 facing away from the second end face 10 of the push rod.
  • the ramp surface 8 extends over the entire face of the first face 9 of the connecting rod 6.
  • the ramp surface 8 is spatially curved and is formed, for example, by a surface of revolution—such as a conical surface.
  • the ramp surface 8 can have at least two areas 8a, 8b with different inclinations in relation to the longitudinal axis 6a of the connecting rod 6 or the axis of rotation 2a of the camshaft 2.
  • a continuous transition is preferably implemented between the two regions 8a, 8b of different inclinations.
  • the angle of inclination ⁇ between the ramp surface 8 (or at least one of the two areas 8a, 8b) and the axis of rotation 2a of the camshaft 2 (shown in figure 5 as the angle between the axis of rotation 2a and a dash-dotted line following the ramp surface 8) is between approximately 30° and 60°, for example.
  • the ramp surface 8 is advantageously designed symmetrically to a longitudinal plane 6b of the push rod 6 containing the longitudinal axis 6a of the push rod 6 .
  • the cam element 3 has a counter-abutment surface 12 which rests on the abutment surface 7 of the connecting rod 6 in the second position B of the cam element 3 .
  • the counter stop surface 12 is, for example - analogous to the stop surface 7 of the push rod 6 - cylindrical.
  • the cam element 3 has a counter-ramp surface 13, on which the ramp surface 8 of the connecting rod 6 acts during the adjustment from the first position A to the second position B.
  • the counter-ramp surface 13 is inclined in accordance with the ramp surface 8 , the shape of the counter-ramp surface 13 corresponding to the shape of the ramp surface 8 .
  • the counter-ramp surface 13 can have at least two sections 13a, 13b with different inclinations, between which a continuous transition is preferably implemented.
  • the angle of inclination ⁇ of the counter-ramp surface 13 to the axis of rotation 2a of the camshaft 2 (shown in figure 5 as the angle between the axis of rotation 2a and a dash-dotted line following the counter-ramp surface 13) is also between 30° and 60°.
  • the counter-ramp surface 13 is arranged axially adjacent to the counter-stop surface 12 and concentrically to the counter-stop surface 12 .
  • the counter-ramp surface 13 is designed as an approximately conical chamfer in the axial connection to the cylindrical counter-stop surface 12 .
  • the conical surface of the counter-ramp surface 13 and the cylindrical surface of the counter-stop surface 12 therefore have the same axis 12a.
  • the spatial contours of the ramp surface 8 and the counter-ramp surface 13 have the advantage that the contact between the ramp surface 8 and the counter-ramp surface 13 when the cam element 3 is deflected via a contact surface and not just - as in the case of a flat ramp surface - via two contact points or contact lines - or even only one point of contact - takes place.
  • the inclinations of the ramp surface 8 and the corresponding counter-ramp surface 13 have the effect that when the push rod 6 is moved from the first push position A1 to the second push position B1, they slide on one another without jerks and without getting caught. Therefore, at least those areas of the ramp surface 8 and the counter-ramp surface 13 that interact when the valve device 1 is used as intended are preferably designed with corresponding inclinations.
  • the cam element 3 has a lifting surface 14 which, in the exemplary embodiment, is approximately symmetrical to a longitudinal plane 3b of the cam element, which runs through the axis 12a of the cylinder surface of the counter-stop surface 12 or the conical surface of the counter-ramp surface 13 .
  • the pivot axis 3a of the cam element 3 is located on one side of the cam element longitudinal plane 3b in the area of the lifting surface 14, in particular in an area between the lifting surface 14 and the counter-ramp surface 13.
  • the cam element 3 has a groove-like recess 15 with a boundary surface 16 on at least one side flank 3c, 3d—preferably on both side flanks.
  • the width d of the groove-like recess 15 is at least as large as the diameter D of a limiting element 17 formed by a limiting pin, which is firmly connected to the camshaft 2 .
  • the limiting pin is inserted into a bore 18 in the camshaft 2 parallel to the axis of rotation 2a of the camshaft 2 .
  • the pivoting movement of the cam element 3 is limited by the limiting element 17 so that damage and undesired noise development are avoided.
  • a reversed embodiment, in which the groove-like recess is formed in the camshaft 2 and the limiting element is formed in the cam element 3, is also possible.
  • the cam element 3 is prestressed in the direction of the first position A by a restoring element 19 formed by a torsion spring (see FIG 2 ). 4 shows the cam element 3 in the pivoted-in first position A caused by the restoring element 19, the push rod 6 being in the first push position A1, which corresponds to the rest position.
  • the cam element 3 is moved into the in figure 5 shown second position B pivoted.
  • the contour of the base cams 4a, 4b is completely covered by the contour of the cam element 3.
  • the solution according to the invention thus allows the realization of different valve lift curves in a simple and low-wear and low-error manner.

Description

Die Erfindung betrifft eine variable Ventiltriebvorrichtung zur Betätigung zumindest eines Gaswechselventiles einer Brennkraftmaschine, mit einer um eine Drehachse drehbar gelagerten Nockenwelle mit zumindest einem über eine Verstellvorrichtung verstellbaren Nockenelement, wobei das Nockenelement zwischen zumindest einer eingeklappten ersten Stellung und einer ausgeklappten zweiten Stellung schwenkbar um eine Schwenkachse gelagert ist, welche parallel zur Drehachse verlaufend und in einem ersten Abstand zu dieser auf der Nockenwelle angeordnet ist, und wobei das verstellbare Nockenelement benachbart in Richtung der Drehachse der Nockenwelle zu zumindest einem starr mit der Nockenwelle verbundenen Basisnocken angeordnet ist, wobei die Verstellvorrichtung zumindest eine innerhalb der Nockenwelle zwischen zumindest einer ersten Schubstellung und einer zweiten Schubstellung verschiebbar angeordnete Schubstange aufweist, wobei die Schubstange zumindest eine vorzugsweise parallel zur Drehachse der Nockenwelle ausgebildete Anschlagfläche für das Nockenelement und zumindest eine geneigt zur Drehachse der Nockenwelle ausgebildete Rampenfläche aufweist, wobei die Rampenfläche auf einer Stirnseite der Schubstange angeordnet ist.The invention relates to a variable valve drive device for actuating at least one gas exchange valve of an internal combustion engine, with a camshaft that is mounted such that it can rotate about an axis of rotation and has at least one cam element that can be adjusted via an adjusting device, the cam element being mounted pivotably about a pivot axis between at least a folded-in first position and a folded-out second position which runs parallel to the axis of rotation and is arranged on the camshaft at a first distance from it, and wherein the adjustable cam element is arranged adjacent in the direction of the axis of rotation of the camshaft to at least one base cam rigidly connected to the camshaft, the adjusting device having at least one inside the camshaft between at least a first thrust position and a second thrust position displaceably arranged push rod, wherein the push rod at least one preferably parallel to the axis of rotation se of the camshaft has a stop surface for the cam element and at least one inclined to the axis of rotation of the camshaft ramp surface, wherein the ramp surface is arranged on an end face of the push rod.

An die Ventiltriebvorrichtungen von Brennkraftmaschinen werden je nach Betriebszustand unterschiedliche Anforderungen gestellt. Bei geringer Last ist es von Vorteil, wenn der Ventilhub geringer ist als bei hoher Last, um die Verbrennungsvorgänge in den einzelnen Zylindern nicht nachteilig zu beeinflussen. Gleichzeitig gibt es Bedarf, die Ventilhubkurve variieren zu können, um das Öffnen und Schließen der Ein- und Auslassventile zu beeinflussen. Es sind daher im Stand der Technik verschiedene Lösungen für variable Ventiltriebe bekannt, um entsprechende Einflussmöglichkeiten bereit zu stellen.Different requirements are placed on the valve train devices of internal combustion engines, depending on the operating state. At low loads, it is advantageous if the valve lift is less than at high loads, so as not to adversely affect the combustion processes in the individual cylinders. At the same time, there is a need to be able to vary the valve lift curve to affect the opening and closing of the intake and exhaust valves. Various solutions for variable valve drives are therefore known in the prior art in order to provide appropriate options for influencing.

Die WO 95/16852 A1 beschreibt eine Lösung, eine in einer hohl ausgeführten Nockenwelle axial verschiebbare Schubstange einzusetzen, um ein Nockenelement aus einer ersten Stellung in eine zweite Stellung auszufahren, um die Ventilhubkurve zu variieren. Die Schubstange weist dabei an ihrer Mantelfläche eine Rampe auf, die auf eine in einer Radialbohrung der Nockenwelle angeordnete Kugel einwirkt, welche eine Innenfläche des verdrehbar gelagerten Nockenelements kontaktiert. Bei einem axialen Verschiebvorgang der Schubstange wird die Kugel in der Radialbohrung bewegt und somit das Nockenelement aus einer ersten Stellung in eine zweite Stellung geschwenkt. Durch diese Lösung sind nur kleine Auslenkungen zwischen erster und zweiter Stellung möglich und es lassen sich nur geringfügige Änderungen an der Ventilhubkurve realisieren. Des Weiteren besteht durch die vielfachen Kontaktflächen zwischen Schubstange, Kugel und Nockenelement das Risiko eines erhöhten Verschleißes.the WO 95/16852 A1 describes a solution for using a push rod that can be displaced axially in a hollow camshaft in order to extend a cam element from a first position to a second position in order to vary the valve lift curve. The push rod has a ramp on its lateral surface which acts on a ball which is arranged in a radial bore of the camshaft and which contacts an inner surface of the rotatably mounted cam element. During an axial displacement process of the connecting rod, the ball is moved in the radial bore and the cam element is thus pivoted from a first position into a second position. With this solution, only small deflections between the first and second positions are possible and only minor changes to the valve lift curve can be implemented. Furthermore, there is the risk of increased wear due to the multiple contact surfaces between the connecting rod, ball and cam element.

Die EP 3 045 690 A2 beschreibt eine variable Ventilbetätigungseinrichtung mit einer Nockenwelle, auf der zwischen zwei Stellungen schwenkbare Nockenelemente angeordnet sind. Die Betätigung jedes schwenkbaren Nockenelements erfolgt über ein innerhalb der Nockenwelle in Richtung der Drehachse der Nockenwelle verschiebbar gelagertes Kolbenelement, welches hydraulisch entgegen einer Rückstellfeder in einer innerhalb der Nockenwelle angeordneten Führungshülse auslenkbar ist. Das Kolbenelement weist auf der Mantelfläche eine Rampe auf, die auf einen quer zum Kolbenelement in einer Radialbohrung der Nockenwelle verschiebbaren Haltestift zusammenwirkt. Wird das Kolbenelement durch Hydraulikdruck ausgelenkt, so schiebt die Rampe den Haltestift in der Radialbohrung der Nockenwelle nach außen, wobei der Haltestift das Nockenelement in seine ausgeschwenkte zweite Stellung drückt und in dieser Stellung hält. Im drucklosen Zustand wird das Kolbenelement durch die Rückstellfeder in die Ruhestellung verschoben, in welcher der Haltestift freigegeben wird und somit das Nockenelement in seine erste Stellung geschwenkt werden kann. In der ausgefahrenen zweiten Stellung kann das Nockenelement über eine Fixiereinrichtung fixiert werden. Die Fixiereinrichtung weist zumindest einen hydraulisch entgegen einer Rückstellfeder betätigbaren Sperrstift auf, welcher in einer exzentrisch in der Nockenwelle angeordneten Führungszylinder verschiebbar gelagert ist und in einer Sperrstellung in ein Stiftloch des Nockenelementes eingreift. Nachteilig ist die große Anzahl an Bauteilen und Kontaktflächen, insbesondere im Kraftfluss zwischen dem Kolbenteil und dem Nockenteil, welche sich ungünstig auf die Gesamttoleranz und das Betätigungsspiel auswirken.the EP 3 045 690 A2 describes a variable valve actuation device with a camshaft on which are arranged pivotable cam elements between two positions. Each pivotable cam element is actuated via a piston element which is mounted within the camshaft so that it can be displaced in the direction of the axis of rotation of the camshaft and which can be deflected hydraulically against a return spring in a guide sleeve arranged within the camshaft. The piston element has a ramp on the lateral surface, which interacts with a retaining pin that can be displaced transversely to the piston element in a radial bore of the camshaft. If the piston element is deflected by hydraulic pressure, the ramp pushes the retaining pin outwards in the radial bore of the camshaft, the retaining pin pressing the cam element into its pivoted-out second position and holding it in this position. In the depressurized state, the piston element is pushed into the rest position by the restoring spring, in which the retaining pin is released and the cam element can thus be pivoted into its first position. In the extended, second position, the cam element can be fixed via a fixing device. The fixing device has at least one locking pin that can be actuated hydraulically against a return spring, which is displaceably mounted in a guide cylinder arranged eccentrically in the camshaft and, in a locking position, engages in a pin hole of the cam element. A disadvantage is the large number of components and contact surfaces, especially in the power flow between the piston part and the cam part, which have an unfavorable effect on the overall tolerance and the actuation play.

Aus der FR 322 489 A ist es bekannt ein schwenkbar in der Nockenwelle gelagerten Nockenelement durch eine in der Nockenwelle verschiebbar angeordnete Schubstange zu betätigen. Die Schubstange weist dabei eine relativ flache Rampenfläche auf, welche durch den Mantel eines kegelstumpfförmigen Abschnitts der Schubstange gebildet ist. Das Nockenelement ist in einem Bereich des Nockens drehbar gelagert, welcher Bereich die höchste Nockenerhebung aufweist. Dadurch kann durch Ausfahren des Nockenelements nur eine Flanke der Erhebungskurve, nicht aber die gesamte Erhebungskurve verändert werden. Insbesondere kann der maximale Hub nicht beeinflusst werden. Ein weiterer Nachteil ist, dass die Rampe durch einen kegelstumpfartigen Bereich der Schubstange gebildet ist. Mit der in der FR 322 489 A gezeigten Ausführung kann das Nockenelement höchstens lediglich um den halben Durchmesser der Schubstange verschoben werden, wobei die Rampenfläche auf eine seitliche Kante des Nockenelementes einwirkt. Eine Gegenrampenfläche am Nockenelement ist nicht vorgesehen - daher kann es zu Fehlbetätigungen und zum Verklemmen kommen, was sich nachteilig auf die Betriebssicherheit auswirkt. Außerdem ist diese bekannte Ventiltriebvorrichtung relativ verschleißanfällig.From the FR 322 489 A it is known to actuate a cam element, which is mounted pivotably in the camshaft, by means of a push rod which is displaceably arranged in the camshaft. The push rod has a relatively flat ramp surface, which is formed by the casing of a frustoconical section of the push rod. The cam element is rotatably mounted in an area of the cam which area has the highest cam elevation. As a result, only one flank of the elevation curve, but not the entire elevation curve, can be changed by extending the cam element. In particular, the maximum stroke cannot be influenced. Another disadvantage is that the ramp is formed by a frusto-conical portion of the push rod. With the in the FR 322 489 A In the embodiment shown, the cam element can be displaced at most only by half the diameter of the push rod, with the ramp surface acting on a lateral edge of the cam element. A counter ramp surface on the cam element is not provided - therefore, incorrect actuation and jamming can occur, which has a negative effect on operational safety. In addition, this known valve drive device is relatively susceptible to wear.

Die DE 10 2016 103 233 A1 offenbart eine variable Ventilbetätigungsvorrichtung, bei der zumindest ein Nockenelement auf der Nockenwelle schwenkbar zwischen einer ersten Stellung und einer zweiten Stellung gelagert ist, wobei ein elastisches Element auf das Nockenelement in Richtung der ausgefahrenen zweiten Stellung einwirkt. In der ausgefahrenen Stellung kann das Nockenelement über eine Fixiereinrichtung fixiert werden. Die Fixiereinrichtung weist auch hier zumindest einen hydraulisch entgegen einer Rückstellfeder betätigbaren Sperrstift auf, welcher in einer exzentrisch in der Nockenwelle angeordneten Führungszylinder verschiebbar gelagert ist und in einer Sperrstellung in ein Stiftloch des Nockenelementes eingreift. Das Nockenelement ist mit einem Antriebselement verbunden, welches mit einem Pressteil zusammenwirkt. Über das Antriebselement kann das Nockenelement durch den Pressteil wieder zurück in die erste Stellung bewegt werden. Die JP 2016 200053 A zeigt eine ähnliche Ventilbetätigungsvorrichtung.the DE 10 2016 103 233 A1 discloses a variable valve actuation device in which at least one cam member is pivotally supported on the camshaft between a first position and a second position, with a resilient member acting on the cam member toward the extended second position. In the extended position, the cam element can be fixed via a fixing device. Here, too, the fixing device has at least one locking pin that can be actuated hydraulically against a return spring, which is displaceably mounted in a guide cylinder arranged eccentrically in the camshaft and, in a locking position, engages in a pin hole of the cam element. The cam element is connected to a drive element which cooperates with a pressing part. The cam element can be moved back into the first position by the pressing part via the drive element. the JP 2016 200053 A shows a similar valve actuation device.

Nachteilig an den bekannten Lösungen ist also teilweise, dass durch die schwenkbaren Nockenelemente bestehende Ventilhebekurven nur beeinflusst, aber nicht geändert werden können. Außerdem sind die Mechanismen zum Verdrehen der Nockenelemente durchwegs aufwändig und verschleiß- bzw. fehleranfällig.A disadvantage of the known solutions is that existing valve lifting curves can only be influenced but not changed by the pivotable cam elements. In addition, the mechanisms for rotating the cam elements are consistently complex and prone to wear and failure.

Es ist daher eine Aufgabe der Erfindung, eine einfache betriebssichere Ventiltriebvorrichtung mit großer Variabilität im Ventilhub bereitzustellen.It is therefore an object of the invention to provide a simple, reliable valve train device with great variability in the valve lift.

Ausgehend von einer Ventiltriebvorrichtung der eingangs genannten Art wird die Aufgabe erfindungsgemäß dadurch gelöst, dass das Nockenelement eine mit der Rampenfläche der Schubstange zusammenwirkende Gegenrampenfläche aufweist, welche zumindest teilweise geneigt zur Drehachse der Nockenwelle ausgebildet ist.Based on a valve drive device of the type mentioned above, the object is achieved according to the invention in that the cam element has a counter-ramp surface which interacts with the ramp surface of the push rod and is designed at least partially inclined to the axis of rotation of the camshaft.

Beim Verschieben der Schubstange gleiten Rampenfläche und Gegenrampenfläche aufeinander. Dadurch kann der Verschleiß verringert und andererseits ein Verklemmen des Mechanismus weitgehend ausgeschlossen werden.When the push rod is moved, the ramp surface and counter-ramp surface slide onto one another. As a result, wear and tear can be reduced and, on the other hand, jamming of the mechanism can be largely ruled out.

Günstigerweise ist das Nockenelement mit der Schubstange in zumindest einer Schubstellung direkt kontaktierbar, sodass die Schubstange unmittelbar auf das Nockenelement einwirkt. Es sind somit keine Übertragungselemente zwischen Schubstange und Nockenelement notwendig. Dies hat den Vorteil, dass die Gesamttoleranz und das Betätigungsspiel geringgehalten werden kann. Somit ist eine viel exaktere Verstellung des Ventilhubes möglich. Zudem wird durch die geringere Anzahl von Punkt- bzw. Flächenkontakten der Verschleiß der Vorrichtung verringert.Favorably, the cam element can be contacted directly with the push rod in at least one push position, so that the push rod acts directly on the cam element. There are therefore no transmission elements between the push rod and cam element necessary. This has the advantage that the overall tolerance and the actuation play can be kept small. Thus, a much more precise adjustment of the valve lift is possible. In addition, the lower Number of point or area contacts reduces the wear of the device.

In einer Ausführungsvariante der Erfindung ist vorgesehen, dass die Rampenfläche auf einer Stirnseite der Schubstange angeordnet ist, wobei vorzugsweis die Rampenfläche sich über die gesamte Stirnfläche der Stirnseite erstreckt. Dadurch ist ein relativ großer Verstellbereich des Ventilhubs zwischen der ersten und der zweiten Stellung des Nockenelementes möglich.In one embodiment variant of the invention, it is provided that the ramp surface is arranged on a front side of the push rod, with the ramp surface preferably extending over the entire front surface of the front side. As a result, a relatively large adjustment range of the valve lift between the first and the second position of the cam element is possible.

Eine Ausführungsvariante der Erfindung sieht vor, dass die Rampenfläche zumindest zwei Bereiche mit unterschiedlichen Neigungswinkeln in Bezug auf die Drehachse der Nockenwelle aufweist. Vorzugsweise ist dabei die Rampenfläche zumindest abschnittsweise räumlich gekrümmt und vorzugsweise durch eine Rotationsfläche gebildet. In einer Variante ist die Rampenfläche durch eine Kegelfläche gebildet. Die Rampenfläche ist somit bevorzugt durch eine Fläche gebildet, welche durch Rotation einer Linie, beispielsweise einer Geraden, um eine Achse erzeugt wird.A variant embodiment of the invention provides that the ramp surface has at least two areas with different angles of inclination in relation to the axis of rotation of the camshaft. The ramp surface is preferably spatially curved at least in sections and is preferably formed by a surface of revolution. In one variant, the ramp surface is formed by a conical surface. The ramp surface is thus preferably formed by a surface which is produced by rotating a line, for example a straight line, about an axis.

Günstigerweise ist die Gegenrampenfläche des Nockenelements zumindest abschnittsweise räumlich gekrümmt. In Varianten ist die Gegenrampenfläche durch eine Rotationsfläche, insbesondere eine Kegelfläche, gebildet. Vorzugsweise weist die Gegenrampenfläche des Nockenelements zumindest zwei Abschnitte mit unterschiedlichen Neigungswinkeln in Bezug auf die Drehachse der Nockenwelle auf.The counter-ramp surface of the cam element is advantageously spatially curved, at least in sections. In variants, the counter-ramp surface is formed by a surface of revolution, in particular a conical surface. Preferably, the counter-ramp surface of the cam element has at least two sections with different angles of inclination with respect to the axis of rotation of the camshaft.

In einer Ausführungsvariante der Erfindung ist vorgesehen, dass die Rampenfläche und/oder die Gegenrampenfläche zumindest abschnittsweise unter einem Neigungswinkel zwischen etwa 30° und 60° zur Drehachse der Nockenwelle geneigt ist/sind. Dadurch ist es möglich, dass bei unvollkommener Verstellung das Nockenelement die Schubstange wieder in die Ruhestellung zurückschiebt und das Nockenelement wieder die eingeschwenkte erste Stellung einnimmt. Eine Selbsthemmung zwischen der Rampenfläche und der Gegenrampenfläche kann dabei weitgehend vermieden werden.In one embodiment variant of the invention, it is provided that the ramp surface and/or the counter-ramp surface is/are inclined at least in sections at an angle of inclination of between approximately 30° and 60° to the axis of rotation of the camshaft. This makes it possible that, if the adjustment is incomplete, the cam element pushes the push rod back into the rest position and the cam element resumes the pivoted-in first position. A self-locking between the ramp surface and the counter-ramp surface can be largely avoided.

In einer weiteren Ausführungsvariante der Erfindung weist das Nockenelement eine mit der Anschlagfläche der Schubstange zusammenwirkende Gegenanschlagfläche auf, welche vorzugsweise zylindrisch ausgebildet ist. Vorzugsweise ist die Gegenanschlagfläche - in Bezug auf die Drehachse der Nockenwelle - axial benachbart zur Gegenrampenfläche angeordnet. Es ist von Vorteil, wenn im Nockenelement die Gegenrampenfläche als Anfasung um die Gegenanschlagfläche ausgebildet ist.In a further embodiment variant of the invention, the cam element has a counter-stop surface which interacts with the stop surface of the push rod and is preferably of cylindrical design. The counter-stop surface is preferably arranged axially adjacent to the counter-ramp surface--in relation to the axis of rotation of the camshaft. It is advantageous if the counter-ramp surface is designed as a chamfer around the counter-stop surface in the cam element.

In der ersten Stellung des Nockenelementes liegt die Gegenrampenfläche des Nockenelementes auf der Rampenfläche der Schubstange an. In der zweiten Stellung des Nockenelementes liegt die Gegenanschlagfläche des Nockenelementes an der Anschlagfläche der Schubstange auf.In the first position of the cam element, the counter-ramp surface of the cam element abuts the ramp surface of the push rod. In the second position of the cam element, the counter-abutment surface of the cam element lies against the abutment surface of the connecting rod.

Besonders vorteilhaft ist es, wenn das Nockenelement durch ein Rückstellelement, das vorzugsweise durch eine Torsionsfeder gebildet ist, in Richtung der ersten Stellung vorgespannt ist. Das Nockenelement wird somit durch das Rückstellelement in seine eingeklappte erste Stellung gedrückt. Durch axiales Verschieben der Schubstange wird das Nockenelement entgegen der Rückstellkraft des Rückstellelementes mittels der Rampenfläche der Schubstange in die ausgeklappte zweite Stellung gedrückt.It is particularly advantageous if the cam element is prestressed in the direction of the first position by a restoring element, which is preferably formed by a torsion spring. The cam element is thus pressed into its folded-in first position by the restoring element. By axial displacement of the push rod, the cam element is pressed against the restoring force of the restoring element by means of the ramp surface of the push rod into the unfolded second position.

Gemäß einer Ausführungsvariante der Erfindung ist vorgesehen, dass zumindest ein fest mit der Nockenwelle verbundenes Begrenzungselement vorgesehen ist, wobei das Nockenelement eine mit dem Begrenzungselement korrespondierende Begrenzungsfläche aufweist, wobei die Begrenzungsfläche des Nockenelementes bei einer maximalen Ausschwenklage des Nockenelementes am Begrenzungselement anliegt. Das Begrenzungselement ist beispielsweise als Begrenzungsstift ausgeführt. Das Begrenzungselement begrenzt die Auslenkbewegung des Nockenelementes nach außen. Dadurch können frühzeitige Verschleißerscheinungen und Schäden vermieden werden.According to one embodiment variant of the invention, it is provided that at least one limiting element is provided which is fixedly connected to the camshaft, the cam element having a limiting surface which corresponds to the limiting element, the limiting surface of the cam element bearing against the limiting element when the cam element is in a maximum swiveling-out position. The delimiting element is designed, for example, as a delimiting pin. The limiting element limits the outward deflection movement of the cam element. This can prevent early signs of wear and damage.

Um eine möglichst weite Verstellung der Hubkurve des Gaswechselventils zu ermöglichen, ist es besonders vorteilhaft, wenn das Nockenelement in der zweiten Stellung die Kontur zumindest eines Basisnockens, vorzugsweise zweier axial an das Nockenelement beidseitig anschließender Basisnocken - in Richtung der Drehachse der Nockenwelle betrachtet - vollständig überdeckt. Dadurch ist es möglich, mit einem einfachen Aufbau völlig verschiedene Hubkurven zu realisieren, während die Lösungen aus dem Stand der Technik überwiegend nur das teilweise Ändern bestehender Hubkurven erlauben.In order to allow the lift curve of the gas exchange valve to be adjusted as far as possible, it is particularly advantageous if the cam element in the second position completely covers the contour of at least one base cam, preferably two base cams axially adjoining the cam element on both sides, viewed in the direction of the axis of rotation of the camshaft . This makes it possible to implement completely different lifting curves with a simple structure, while the solutions from the prior art mostly only allow existing lifting curves to be partially changed.

Dier Erfindung wird im Folgenden an Hand des in den Figuren dargestellten, nicht einschränkenden Ausführungsbeispiels näher erläutert. Darin zeigen:

Fig. 1
eine erfindungsgemäße variable Ventiltriebvorrichtung in einer axonometrischen Darstellung;
Fig. 2
die Ventiltriebvorrichtung in einer Explosionsdarstellung;
Fig. 3
ein Nockenelement der Ventiltriebvorrichtung in einer axonometrischen Darstellung;
Fig. 4
die Ventiltriebvorrichtung in einer ersten Stellung des Nockenelementes in einer geschnittenen Darstellung; und
Fig. 5
die Ventiltriebvorrichtung in einer zweiten Stellung des Nockenelementes in einer geschnittenen Darstellung.
The invention is explained in more detail below with reference to the non-limiting exemplary embodiment illustrated in the figures. Show in it:
1
a variable valve drive device according to the invention in an axonometric representation;
2
the valve drive device in an exploded view;
3
a cam element of the valve train device in an axonometric view;
4
the valve drive device in a first position of the cam element in a sectional view; and
figure 5
the valve drive device in a second position of the cam element in a sectional view.

Fig. 1 zeigt eine variable Ventiltriebvorrichtung 1 zur Betätigung zumindest eines - nicht weiter dargestellten - Gaswechselventiles einer Brennkraftmaschine. Die Ventilbetätigungseinrichtung 1 weist eine um eine Drehachse 2a drehbar gelagerte Nockenwelle 2 mit zumindest einem über eine Verstellvorrichtung 20 verstellbaren Nockenelement 3 auf. Das Nockenelement 3 ist zwischen einer eingeklappten ersten Stellung A (Fig. 4) und einer ausgeklappten zweiten Stellung B (Fig. 5) schwenkbar um eine Schwenkachse 3a gelagert. Diese Schwenkachse 3a ist parallel zur Drehachse 2a der Nockenwelle 2 ausgerichtet und in einem ersten Abstand a zu dieser auf der Nockenwelle 2 angeordnet. Mit anderen Worten ist das Nockenelement 3 schwenkbar in der Nockenwelle 2 gelagert, wobei die Schwenkachse 3a des Nockenelements 3 parallel zur und in einem ersten Abstand a von der Drehachse 2a der Nockenwelle 2 verläuft. 1 shows a variable valve train device 1 for actuating at least one gas exchange valve of an internal combustion engine (not shown in more detail). The valve-actuating device 1 has a camshaft 2 that is rotatably mounted about an axis of rotation 2a and has at least one cam element 3 that can be adjusted via an adjusting device 20 . The cam element 3 is between a folded first position A ( 4 ) and an unfolded second position B ( figure 5 ) pivoted about a pivot axis 3a. This pivot axis 3a is aligned parallel to the axis of rotation 2a of the camshaft 2 and is arranged on the camshaft 2 at a first distance a therefrom. In other words, the cam element 3 is mounted pivotably in the camshaft 2 , the pivot axis 3a of the cam element 3 running parallel to and at a first distance a from the axis of rotation 2a of the camshaft 2 .

Das verstellbare Nockenelement 3 ist in Richtung der Drehachse 2a der Nockenwelle 2 benachbart zu zwei Basisnocken 4a, 4b eines Nockenkörpers 4 angeordnet. Der Nockenkörper 4 weist dabei eine Aufnahme 5 aus, in der das Nockenelement 3 überwiegend aufgenommen ist und in welche das Nockenelement 3 eingeschwenkt werden kann.The adjustable cam element 3 is arranged adjacent to two base cams 4a, 4b of a cam body 4 in the direction of the axis of rotation 2a of the camshaft 2 . The cam body 4 has a receptacle 5 in which the cam element 3 is predominantly accommodated and into which the cam element 3 can be pivoted.

Mit Bezugszeichen 21 ist ein Nockenfolgeelement, beispielsweise ein Kipphebel bezeichnet, welcher über eine Rolle 22 am Basisnocken 4a, 4b oder am Nockenelement 3 anliegt und entsprechend der Nockenkontur des Basisnockens 4a, 4b oder des Nockenelements 3 ausgelenkt wird. Das Nockenfolgeelement 21 wirkt auf zumindest ein nicht dargestelltes Gaswechselventil der Brennkraftmaschine ein und steuert dessen Hub.Reference numeral 21 designates a cam follower element, for example a rocker arm, which rests against base cam 4a, 4b or cam element 3 via a roller 22 and is deflected according to the cam contour of base cam 4a, 4b or cam element 3. The cam follower element 21 acts on at least one gas exchange valve (not shown) of the internal combustion engine and controls its stroke.

Die Verstellvorrichtung 20 weist zumindest eine innerhalb der Nockenwelle 2 verschiebbar angeordnete Schubstange 6 mit im Wesentlichen zylindrischer Form auf, wobei die Schubstange 6 zwischen einer ersten Schubstellung A1 und einer zweiten Schubstellung B1 axial - also parallel zur Drehachse 2a der Nockenwelle 2 - verschoben werden kann. Die erste Schubstellung A1 korrespondiert dabei mit der ersten Stellung A des Nockenelementes 3. Die zweite Schubstellung B1 korrespondiert mit der zweiten Stellung B des Nockenelementes 3. Die Schubstange 6 ist im Ausführungsbeispiel zylindrisch ausgebildet, es ist aber auch eine prismatische oder andere Form möglich. Die Schubstange 6 ist achsgleich zur Nockenwelle 2 angeordnet - die Längsachse 6a der Schubstange 6 fällt also mit der Drehachse 2a der Nockenwelle 2 zusammen.Adjusting device 20 has at least one push rod 6 with a substantially cylindrical shape that is slidably disposed within camshaft 2, wherein push rod 6 can be displaced axially—i.e., parallel to axis of rotation 2a of camshaft 2—between a first thrust position A1 and a second thrust position B1. The first thrust position A1 corresponds to the first position A of the cam element 3. The second thrust position B1 corresponds to the second position B of the cam element 3. The push rod 6 is cylindrical in the exemplary embodiment, but a prismatic or other shape is also possible. The connecting rod 6 has the same axis as the camshaft 2 arranged - the longitudinal axis 6a of the push rod 6 thus coincides with the axis of rotation 2a of the camshaft 2 together.

Die Schubstange 6 weist eine parallel zur Drehachse 2a der Nockenwelle 2 ausgebildete Anschlagfläche 7 für das Nockenelement 3 auf. Die Anschlagfläche 7 ist durch die zylindrische Mantelfläche der Schubstange 6 gebildet und dient als Anschlag für das Nockenelement 3 in der ausgeklappten zweiten Stellung. Durch die Anschlagfläche 7 wird also ein Zurückschwenken des ausgeschwenkten Nockenelementes 3 von der zweiten Stellung B in die erste Stellung A verhindertThe push rod 6 has a stop surface 7 for the cam element 3 which is parallel to the axis of rotation 2a of the camshaft 2 . The stop surface 7 is formed by the cylindrical outer surface of the push rod 6 and serves as a stop for the cam element 3 in the unfolded second position. The stop surface 7 thus prevents the pivoted-out cam element 3 from pivoting back from the second position B into the first position A

Weiters weist die Schubstange 6 eine geneigt zur Drehachse 2a der Nockenwelle 2 ausgebildete Rampenfläche 8 auf. Die Rampenfläche 8 dient dazu, um die axiale Bewegung der Schubstange 6 in eine radiale Ausschwenkbewegung des Nockenelements 3 zu transferieren und das Nockenelement 3 von der ersten Stellung A in die zweite Stellung B zu bewegen.Furthermore, the push rod 6 has a ramp surface 8 that is inclined to the axis of rotation 2a of the camshaft 2 . The ramp surface 8 serves to transfer the axial movement of the push rod 6 into a radial pivoting movement of the cam element 3 and to move the cam element 3 from the first position A to the second position B.

Die Rampenfläche 8 ist auf einer ersten Stirnseite 9 der Schubstange 6 angeordnet. Die Verschiebung der Schubstange 6 erfolgt über einen mit Bezugszeichen 11 in Fig. 1, Fig. 4 und Fig. 5 angedeuteten Aktuator - z.B. hydraulisch, pneumatisch, elektrisch, elektromagnetisch oder anders aktuierbar -, welcher beispielsweise an einer der ersten Stirnseite 9 abgewandten zweiten Stirnseite 10 der Schubstange angreift.The ramp surface 8 is arranged on a first end face 9 of the push rod 6 . The displacement of the push rod 6 takes place via a reference number 11 in 1 , 4 and 5 indicated actuator - for example, hydraulically, pneumatically, electrically, electromagnetically or otherwise actuatable - which acts, for example, on one of the first end face 9 facing away from the second end face 10 of the push rod.

Im Ausführungsbeispiel erstreckt sich die Rampenfläche 8 über die gesamte Stirnfläche der ersten Stirnseite 9 der Schubstange 6.In the exemplary embodiment, the ramp surface 8 extends over the entire face of the first face 9 of the connecting rod 6.

Die Rampenfläche 8 ist im Ausführungsbeispiel räumlich gekrümmt und beispielsweise durch eine Rotationsfläche - etwa eine Kegelfläche - gebildet. Die Rampenfläche 8 kann zumindest zwei Bereiche 8a, 8b mit unterschiedlichen Neigungen in Bezug zur Längsachse 6a der Schubstange 6 bzw. Drehachse 2a der Nockenwelle 2 aufweisen. Vorzugsweise ist dabei zwischen den zwei Bereichen 8a, 8b unterschiedlicher Neigung ein stetiger Übergang ausgeführt. Der Neigungswinkel β zwischen der Rampenfläche 8 (bzw. zumindest einem der zwei Bereiche 8a, 8b) und der Drehachse 2a der Nockenwelle 2 (eingezeichnet in Fig. 5 als Winkel zwischen der Drehachse 2a und einer der Rampenfläche 8 folgenden strichpunktierten Linie) beträgt beispielsweise zwischen etwa 30° und 60°. Die Rampenfläche 8 ist günstigerweise symmetrisch zu einer die Längsachse 6a der Schubstange 6 beinhaltenden Längsebene 6b der Schubstange 6 ausgebildet.In the exemplary embodiment, the ramp surface 8 is spatially curved and is formed, for example, by a surface of revolution—such as a conical surface. The ramp surface 8 can have at least two areas 8a, 8b with different inclinations in relation to the longitudinal axis 6a of the connecting rod 6 or the axis of rotation 2a of the camshaft 2. A continuous transition is preferably implemented between the two regions 8a, 8b of different inclinations. The angle of inclination β between the ramp surface 8 (or at least one of the two areas 8a, 8b) and the axis of rotation 2a of the camshaft 2 (shown in figure 5 as the angle between the axis of rotation 2a and a dash-dotted line following the ramp surface 8) is between approximately 30° and 60°, for example. The ramp surface 8 is advantageously designed symmetrically to a longitudinal plane 6b of the push rod 6 containing the longitudinal axis 6a of the push rod 6 .

Wie insbesondere aus Fig. 3 hervorgeht, weist das Nockenelement 3 eine Gegenanschlagfläche 12 auf, welche in der zweiten Stellung B des Nockenelementes 3 auf der Anschlagfläche 7 der Schubstange 6 aufliegt. Die Gegenanschlagfläche 12 ist beispielsweise - analog zur Anschlagfläche 7 der Schubstange 6 - zylindrisch geformt.Like in particular 3 shows, the cam element 3 has a counter-abutment surface 12 which rests on the abutment surface 7 of the connecting rod 6 in the second position B of the cam element 3 . The counter stop surface 12 is, for example - analogous to the stop surface 7 of the push rod 6 - cylindrical.

Das Nockenelement 3 weist eine Gegenrampenfläche 13 auf, auf welche die Rampenfläche 8 der Schubstange 6 bei der Verstellung von der ersten Stellung A in die zweite Stellung B einwirkt. Die Gegenrampenfläche 13 ist entsprechend der Rampenfläche 8 geneigt, wobei die Form der Gegenrampenfläche 13 mit der Form der Rampenfläche 8 korrespondiert. Die Gegenrampenfläche 13 kann - wie die Rampenfläche 8 - zumindest zwei Abschnitte 13a, 13b mit unterschiedlichen Neigungen aufweisen, zwischen denen vorzugsweise ein stetiger Übergang ausgeführt ist. Der Neigungswinkel γ der Gegenrampenfläche 13 zur Drehachse 2a der Nockenwelle 2 (eingezeichnet in Fig. 5 als Winkel zwischen der Drehachse 2a und einer der Gegenrampenfläche 13 folgenden strichpunktierten Linie) beträgt ebenfalls zwischen 30° und 60°. Im Ausführungsbeispiel ist die Gegenrampenfläche 13 axial benachbart zur Gegenanschlagfläche 12 und konzentrisch zur Gegenanschlagfläche 12 angeordnet. Im Ausführungsbeispiel ist die Gegenrampenfläche 13 als etwa konische Anfasung im axialen Anschluss an die zylindrische Gegenanschlagfläche 12 ausgebildet. Die Kegelfläche der Gegenrampenfläche 13 und die Zylinderfläche der Gegenanschlagfläche 12 weisen also die gleiche Achse 12a auf. Die räumlichen Konturen der Rampenfläche 8 und der Gegenrampenfläche 13 haben den Vorteil, dass die Berührung zwischen Rampenfläche 8 und Gegenrampenfläche 13 bei Auslenkung des Nockenelements 3 über eine Kontaktfläche und nicht nur - wie bei einer ebenen Rampenfläche - über zwei Kontaktpunkte, oder Kontaktlinien - oder gar nur einen Kontaktpunkt - erfolgt.The cam element 3 has a counter-ramp surface 13, on which the ramp surface 8 of the connecting rod 6 acts during the adjustment from the first position A to the second position B. The counter-ramp surface 13 is inclined in accordance with the ramp surface 8 , the shape of the counter-ramp surface 13 corresponding to the shape of the ramp surface 8 . Like the ramp surface 8, the counter-ramp surface 13 can have at least two sections 13a, 13b with different inclinations, between which a continuous transition is preferably implemented. The angle of inclination γ of the counter-ramp surface 13 to the axis of rotation 2a of the camshaft 2 (shown in figure 5 as the angle between the axis of rotation 2a and a dash-dotted line following the counter-ramp surface 13) is also between 30° and 60°. In the exemplary embodiment, the counter-ramp surface 13 is arranged axially adjacent to the counter-stop surface 12 and concentrically to the counter-stop surface 12 . In the exemplary embodiment, the counter-ramp surface 13 is designed as an approximately conical chamfer in the axial connection to the cylindrical counter-stop surface 12 . The conical surface of the counter-ramp surface 13 and the cylindrical surface of the counter-stop surface 12 therefore have the same axis 12a. The spatial contours of the ramp surface 8 and the counter-ramp surface 13 have the advantage that the contact between the ramp surface 8 and the counter-ramp surface 13 when the cam element 3 is deflected via a contact surface and not just - as in the case of a flat ramp surface - via two contact points or contact lines - or even only one point of contact - takes place.

Die Neigungen der Rampenfläche 8 und der korrespondierenden Gegenrampenfläche 13 bewirken, dass diese beim Verschieben der Schubstange 6 von der ersten Schubstellung A1 in die zweite Schubstellung B1 ruckfrei und ohne Verhaken aufeinander gleiten. Daher sind vorzugsweise zumindest diejenigen Bereiche der Rampenfläche 8 und der Gegenrampenfläche 13, die bei bestimmungsgemäßer Verwendung der Ventilvorrichtung 1 zusammenwirken, mit korrespondierenden Neigungen ausgeführt.The inclinations of the ramp surface 8 and the corresponding counter-ramp surface 13 have the effect that when the push rod 6 is moved from the first push position A1 to the second push position B1, they slide on one another without jerks and without getting caught. Therefore, at least those areas of the ramp surface 8 and the counter-ramp surface 13 that interact when the valve device 1 is used as intended are preferably designed with corresponding inclinations.

Ein Verklemmen oder Verspannen der sich berührenden Teile wird somit vermieden. Zusammen mit dem erwähnten Neigungswinkeln β, γ der Rampenfläche 8 und der Gegenrampenfläche 13 wird außerdem bewirkt, dass Fehlschaltungen und ungewünschte Zwischenstellungen des Nockenelementes 3 zwischen der ersten Stellung A und der zweiten Stellung B vermieden werden. Ist die Bewegung der Schubstange 6 von der ersten Schubstellung A1 in die zweite Schubstellung B1 unvollkommen oder wird dazwischen abgebrochen, so kann die Schubstange 6 über die Rampenfläche 8 und die Gegenrampenfläche 13 durch das Nockenelement 3 wieder zurück in die erste Schubstellung A1 bewegt werden. Voraussetzung ist, dass die Neigungswinkeln β, γ der Rampenfläche 8 und der Gegenrampenfläche 13 in Bezug zur Drehachse 2a der Nockenwelle 2 groß genug ausgeführt sind, um eine Selbsthemmung zu vermeiden.Jamming or tensioning of the touching parts is thus avoided. Together with the aforementioned angles of inclination β, γ of the ramp surface 8 and the counter-ramp surface 13, this also has the effect that faulty switching and undesired intermediate positions of the cam element 3 between the first position A and the second position B are avoided. If the movement of the push rod 6 from the first push position A1 to the second push position B1 is incomplete or interrupted in between, the push rod 6 can be moved back to the first push position A1 via the ramp surface 8 and the counter-ramp surface 13 by the cam element 3. Requirement is, that the angles of inclination β, γ of the ramp surface 8 and the counter-ramp surface 13 in relation to the axis of rotation 2a of the camshaft 2 are large enough to avoid self-locking.

Das Nockenelement 3 weist eine Hubfläche 14 auf, welche im Ausführungsbeispiel etwa symmetrisch zu einer Nockenelementlängsebene 3b ausgebildet ist, die durch die Achse 12a der Zylinderfläche der Gegenanschlagfläche 12 bzw. der Kegelfläche der Gegenrampenfläche 13 verläuft. Die Schwenkachse 3a des Nockenelements 3 befindet sich auf einer Seite der Nockenelementlängsebene 3b im Bereich der Hubfläche 14, insbesondere in einem Bereich zwischen der Hubfläche 14 und der Gegenrampenfläche 13.The cam element 3 has a lifting surface 14 which, in the exemplary embodiment, is approximately symmetrical to a longitudinal plane 3b of the cam element, which runs through the axis 12a of the cylinder surface of the counter-stop surface 12 or the conical surface of the counter-ramp surface 13 . The pivot axis 3a of the cam element 3 is located on one side of the cam element longitudinal plane 3b in the area of the lifting surface 14, in particular in an area between the lifting surface 14 and the counter-ramp surface 13.

In einem zweiten Abstand b zur Schwenkachse 3a weist das Nockenelement 3 an zumindest einer Seitenflanke 3c, 3d - bevorzugt jeweils an beiden Seitenflanken - eine nutartige Ausnehmung 15 mit einer Begrenzungsfläche 16 auf. Die Breite d der nutartigen Ausnehmung 15 ist dabei mindestens so groß wie der Durchmesser D eines durch einen Begrenzungsstift gebildeten Begrenzungselementes 17, welches fest mit der Nockenwelle 2 verbunden ist. Der Begrenzungsstift ist in eine Bohrung 18 der Nockenwelle 2 parallel zur Drehachse 2a der Nockenwelle 2 eingesetzt. Durch das Begrenzungselement 17 wird die Ausschwenkbewegung des Nockenelementes 3 begrenzt, sodass Schäden und ungewünschte Geräuschentwicklung vermieden werden. Auch eine umgekehrte Ausführung, bei der also die nutartige Ausnehmung in der Nockenwelle 2 und das Begrenzungselement im Nockenelement 3 ausgeführt sind, ist möglich.At a second distance b from the pivot axis 3a, the cam element 3 has a groove-like recess 15 with a boundary surface 16 on at least one side flank 3c, 3d—preferably on both side flanks. The width d of the groove-like recess 15 is at least as large as the diameter D of a limiting element 17 formed by a limiting pin, which is firmly connected to the camshaft 2 . The limiting pin is inserted into a bore 18 in the camshaft 2 parallel to the axis of rotation 2a of the camshaft 2 . The pivoting movement of the cam element 3 is limited by the limiting element 17 so that damage and undesired noise development are avoided. A reversed embodiment, in which the groove-like recess is formed in the camshaft 2 and the limiting element is formed in the cam element 3, is also possible.

Das Nockenelement 3 ist durch ein durch eine Torsionsfeder gebildetes Rückstellelement 19 in Richtung der ersten Stellung A vorgespannt (siehe Fig. 2). Fig. 4 zeigt das Nockenelement 3 in der durch das Rückstellelement 19 bewirkten eingeschwenkten ersten Stellung A, wobei sich die Schubstange 6 in der ersten Schubstellung A1 befindet, welche der Ruhestellung entspricht.The cam element 3 is prestressed in the direction of the first position A by a restoring element 19 formed by a torsion spring (see FIG 2 ). 4 shows the cam element 3 in the pivoted-in first position A caused by the restoring element 19, the push rod 6 being in the first push position A1, which corresponds to the rest position.

Wird die Schubstange 6 durch den Aktuator 11 von der ersten Schubstellung A1 in die zweite Schubstellung B1 bewegt, so wird durch die Rampenfläche 8 und die Gegenrampenfläche 13 das Nockenelement 3 in die in Fig. 5 dargestellte zweite Stellung B ausgeschwenkt. In der zweiten Stellung B findet - in Richtung der Drehachse 2a der Nockenwelle 2 betrachtet - eine vollständige Überdeckung der Kontur der Basisnocken 4a, 4b durch die Kontur des Nockenelementes 3 statt.If the push rod 6 is moved by the actuator 11 from the first push position A1 to the second push position B1, the cam element 3 is moved into the in figure 5 shown second position B pivoted. In the second position B--viewed in the direction of the axis of rotation 2a of the camshaft 2--the contour of the base cams 4a, 4b is completely covered by the contour of the cam element 3.

Sobald die Schubstange 3 wieder von der in Fig. 5 gezeigten zweiten Schubstellung B1 in die in Fig. 4 dargestellte erste Schubstellung A1 zurückgezogen wird, wird das Nockenelement 3 durch das Rückstellelement 19 wieder in die erste Stellung A zurückgeschwenkt.As soon as the push rod 3 is released from the in figure 5 shown second thrust position B1 in the in 4 shown first pushing position A1 is retracted, the cam element 3 is pivoted back into the first position A by the return element 19 .

Die erfindungsgemäße Lösung erlaubt damit die Realisierung von unterschiedlichen Ventilhebekurven auf einfache und verschleiß- und fehlerarme Weise.The solution according to the invention thus allows the realization of different valve lift curves in a simple and low-wear and low-error manner.

Claims (16)

  1. Variable valve drive device (1) for actuating at least one gas exchange valve of an internal combustion engine, comprising a camshaft (2) which is mounted such as to be rotatable about an axis of rotation (2a), said camshaft having at least one cam element (3) which is adjustable by way of an adjusting device (20), wherein the cam element (3) is mounted such as to be pivotable about a pivot axis (3a) between at least a folded-in first position (A) and a folded-out second position (B), said pivot axis extending parallel to the axis of rotation (2a) and being arranged at a first distance (a) therefrom on the camshaft (2), and wherein the adjustable cam element (3), in the direction of the axis of rotation (2a) of the camshaft (2), is arranged adjacent to at least one base cam (4a, 4b) which is rigidly connected to the camshaft (2), wherein the adjusting device (20) comprises at least one push rod (6) which is arranged such as to be displaceable within the camshaft (2) between at least a first push position (A1) and a second push position (B1), wherein the push rod (6) has at least one stop surface (7) for the cam element (3), said stop surface preferably being formed parallel to the axis of rotation (2a) of the camshaft (2), and at least one ramp surface (8) which is formed at least in part inclined relative to the axis of rotation (2a) of the camshaft (2), characterised in that the cam element (3) has a mating ramp surface (13) which cooperates with the ramp surface (8) of the push rod (6) and which is formed at least in part inclined relative to the axis of rotation (2a) of the camshaft (2), wherein the ramp surface (8) is arranged on an end face (9) of the push rod (6).
  2. Valve drive device (1) according to claim 1, characterised in that the cam element (3) can be contacted directly by the push rod (6) in at least one push position (A1, B1), so that the push rod (6) acts directly on the cam element (3).
  3. Valve drive device (1) according to claim 1 or 2, characterised in that the ramp surface (8) extends over the entire end surface of the end face (9).
  4. Valve drive device (1) according to any one of claims 1 to 3, characterised in that the ramp surface (8) has at least two regions (8a, 8b) with different angles of inclination (β) relative to the axis of rotation (2a) of the camshaft (2).
  5. Valve drive device (1) according to any one of claims 1 to 4, characterised in that the ramp surface (8) is at least in part spatially curved and is preferably formed by a surface of revolution.
  6. Valve drive device (1) according to claim 5, characterised in that the ramp surface (8) is formed by a conical surface.
  7. Valve drive device (1) according to any one of claims 1 to 6, characterised in that the mating ramp surface (13) of the cam element (3) is at least in part spatially curved.
  8. Valve drive device (1) according to any one of claims 1 to 7, characterised in that the mating ramp surface (13) of the cam element (3) has at least two portions (13a, 13b) with different angles of inclination (γ) relative to the axis of rotation (2a) of the camshaft (2).
  9. Valve drive device (1) according to any one of claims 1 to 8, characterised in that the ramp surface (8) and/or the mating ramp surface (13) is/are at least in part inclined at an angle of inclination (β, γ) of between approximately 30° and 60° relative to the axis of rotation (2a) of the camshaft (2).
  10. Valve drive device (1) according to any one of claims 1 to 9, characterised in that the cam element (3) has a mating stop surface (12) which cooperates with the stop surface (7) of the push rod (6) and which is preferably formed cylindrically.
  11. Valve drive device (1) according to claim 10, characterised in that the mating stop surface (12) is arranged axially adjacent to the mating ramp surface (13) relative to the axis of rotation (2a) of the camshaft (2).
  12. Valve drive device (1) according to claim 10 or 11, characterised in that the mating ramp surface (13) is designed as a chamfer around the mating stop surface (12).
  13. Valve drive device (1) according to any one of claims 1 to 12, characterised in that the cam element (3) is biased towards the first position (A) by a return element (19), which is preferably formed by a torsion spring.
  14. Valve drive device (1) according to any one of claims 1 to 13, characterised in that at least one limiting element (17) is provided, which is fixedly connected to the camshaft (2), wherein the cam element (3) has a limiting surface (16) corresponding to the limiting element (17), wherein the limiting surface (16) of the cam element (3) bears against the limiting element (17) when the cam element (3) is pivoted out to the maximum extent.
  15. Valve drive device (1) according to claim 14, characterised in that the limiting element (17) is designed as a limiting pin.
  16. Valve drive device (1) according to any one of claims 1 to 15, characterised in that, as viewed in the direction of the axis of rotation (2a) of the camshaft (2), the cam element (3) in the second position (B) completely overlies the contour of at least one base cam (4a, 4b), preferably of two base cams (4a, 4b) axially adjoining the cam element (3) on both sides.
EP19745032.3A 2018-07-16 2019-07-16 Variable valve drive device Active EP3824165B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ATA50612/2018A AT521559B1 (en) 2018-07-16 2018-07-16 VARIABLE VALVE GEAR DEVICE
PCT/AT2019/060237 WO2020014722A1 (en) 2018-07-16 2019-07-16 Variable valve drive device

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EP3824165B1 true EP3824165B1 (en) 2022-03-30

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE69421170T2 (en) * 1993-12-17 2000-07-06 Christos Valasopoulos CAM TIP WITH Eccentric Rotation
WO2002081872A1 (en) * 2001-04-05 2002-10-17 Stephen William Mitchell Variable valve timing system
EP3045690B1 (en) * 2015-01-15 2019-03-27 Toyota Jidosha Kabushiki Kaisha Variable valve apparatus for internal combustion engine

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR322489A (en) * 1902-06-25 1903-02-06 Des Anciens Etablissements Panhard Et Levassor Further training in the construction of internal combustion engines
FR569928A (en) * 1923-08-20 1924-04-19 Cam control device
US5855190A (en) * 1996-09-24 1999-01-05 Yamaha Hatsudoki Kabushiki Kaisha Valve-actuating variable cam for engine
AU2003208163A1 (en) * 2002-03-28 2003-10-13 Stefan Battlogg Device for converting a rotational displacement into a displacement back and forth
DE10242235A1 (en) * 2002-09-12 2004-03-25 Daimlerchrysler Ag Camshaft with variable valve control for IC engine has an additional cam profile controlled by a servo drive with infinite adjustment
JP6252528B2 (en) 2015-03-19 2017-12-27 トヨタ自動車株式会社 Variable valve operating device for internal combustion engine
JP6295991B2 (en) 2015-04-09 2018-03-20 トヨタ自動車株式会社 Variable valve operating device for internal combustion engine

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE69421170T2 (en) * 1993-12-17 2000-07-06 Christos Valasopoulos CAM TIP WITH Eccentric Rotation
WO2002081872A1 (en) * 2001-04-05 2002-10-17 Stephen William Mitchell Variable valve timing system
EP3045690B1 (en) * 2015-01-15 2019-03-27 Toyota Jidosha Kabushiki Kaisha Variable valve apparatus for internal combustion engine

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WO2020014722A1 (en) 2020-01-23
AT521559B1 (en) 2022-08-15
EP3824165A1 (en) 2021-05-26

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